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Zhang L, Zhu D, Jiang J, Min Z, Fa Z. The ubiquitin E3 ligase MDM2 induces chemoresistance in colorectal cancer by degradation of ING3. Carcinogenesis 2023; 44:562-575. [PMID: 37279970 DOI: 10.1093/carcin/bgad040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 05/12/2023] [Accepted: 06/06/2023] [Indexed: 06/08/2023] Open
Abstract
Chemoresistance is an obstacle for colorectal cancer (CRC) treatment. This study investigates the role of the ubiquitin E3 ligase MDM2 in affecting cell growth and chemosensitivity in CRC cells by modifying the transcription factor inhibitor of growth protein 3 (ING3). The expression of MDM2 and ING3 in CRC tissues was predicted by bioinformatics analysis, followed by expression validation and their interaction in CRC HCT116 and LS180 cells. Ectopic overexpression or knockdown of MDM2/ING3 was performed to test their effect on proliferation and apotptosis as well as chemosensitivity of CRC cells. Finally, the effect of MDM2/ING3 expression on the in vivo tumorigenesis of CRC cells was examined through subcutaneous tumor xenograft experiment in nude mice. MDM2 promoted ubiquitin-proteasome pathway degradation of ING3 through ubiquitination and diminished its protein stability. Overexpression of MDM2 downregulated ING3 expression, which promoted CRC cell proliferation and inhibited the apoptosis. The enhancing role of MDM2 in tumorigenesis and resistance to chemotherapeutic drugs was also confirmed in vivo. Our findings highlight that MDM2 modifies the transcription factor ING3 by ubiquitination-proteasome pathway degradation, thus reducing ING3 protein stability, which finally promotes CRC cell growth and chemoresistance.
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Affiliation(s)
- Liangliang Zhang
- General Surgery Department, Wujin Hospital Affiliated with Jiangsu University, The Wujin Clinical College of Xuzhou Medical University, Changzhou 213004, P. R. China
| | - Dagang Zhu
- General Surgery Department, Wujin Hospital Affiliated with Jiangsu University, The Wujin Clinical College of Xuzhou Medical University, Changzhou 213004, P. R. China
| | - Jiwen Jiang
- General Surgery Department, Wujin Hospital Affiliated with Jiangsu University, The Wujin Clinical College of Xuzhou Medical University, Changzhou 213004, P. R. China
| | - Zhenyu Min
- General Surgery Department, Wujin Hospital Affiliated with Jiangsu University, The Wujin Clinical College of Xuzhou Medical University, Changzhou 213004, P. R. China
| | - Zhenzhong Fa
- General Surgery Department, Wujin Hospital Affiliated with Jiangsu University, The Wujin Clinical College of Xuzhou Medical University, Changzhou 213004, P. R. China
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2
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Zhi Y, Zhang S, Zi M, Wang Y, Liu Y, Zhang M, Shi L, Yan Q, Zeng Z, Xiong W, Zhi K, Gong Z. Potential applications of N 6 -methyladenosine modification in the prognosis and treatment of cancers via modulating apoptosis, autophagy, and ferroptosis. WILEY INTERDISCIPLINARY REVIEWS. RNA 2022; 13:e1719. [PMID: 35114735 DOI: 10.1002/wrna.1719] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/13/2021] [Accepted: 01/11/2022] [Indexed: 12/30/2022]
Abstract
N6 -methyladenosine (m6 A) is one of the most abundant modifications determining the fate of RNA. Currently, m6 A modification is tightly connected with tumorigenesis and presents novel promise in clinical applications. Regulated cell death (RCD) is a programmed mechanism that plays a complicated role in malignant transition. Regarding the main forms of RCD, aberrant levels of m6 A modification have been detected during the progression of apoptosis, autophagy, ferroptosis, necroptosis, and pyroptosis in several diseases. However, few reviews have elucidated the correlation between m6 A-modified RCD and carcinogenesis. In this review, we summarize the regulators of m6 A methylation and their functions in carcinogenesis through an overview of m6 A-modified RCD. Additionally, we assume the potential role of m6 A modification regulators as novel biomarkers for chemotherapies and precision medicine. Furthermore, we review the controversies and conflicts in m6 A explorations and predict future orientations of m6 A-modified RCD for clinical applications. This article is categorized under: Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.
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Affiliation(s)
- Yuan Zhi
- Department of Oral and Maxillofacial Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Shanshan Zhang
- Department of Stomatology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Moxin Zi
- Department of Oral and Maxillofacial Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Yian Wang
- Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Yuhang Liu
- Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Mi Zhang
- Department of Oral and Maxillofacial Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China.,Key Laboratory of Carcinogenesis and Cancer Invasion of Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Lei Shi
- Department of Oral and Maxillofacial Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Qijia Yan
- Department of Stomatology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Zhaoyang Zeng
- NHC Key Laboratory of Carcinogenesis and Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Wei Xiong
- NHC Key Laboratory of Carcinogenesis and Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, China.,Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Keqian Zhi
- Department of Oral and Maxillofacial Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Zhaojian Gong
- Department of Oral and Maxillofacial Surgery, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
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3
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Melekhova A, Baniahmad A. ING Tumour Suppressors and ING Splice Variants as Coregulators of the Androgen Receptor Signalling in Prostate Cancer. Cells 2021; 10:cells10102599. [PMID: 34685579 PMCID: PMC8533759 DOI: 10.3390/cells10102599] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 09/25/2021] [Accepted: 09/28/2021] [Indexed: 12/12/2022] Open
Abstract
Prevention and overcoming castration resistance of prostate cancer (PC) remains one of the main unsolved problems in modern oncology. Hence, many studies are focused on the investigation of novel androgen receptor (AR) regulators that could serve as potential drug targets in disease therapy. Among such factors, inhibitor of growth (ING) proteins were identified. Some ING proteins act as AR transcriptional coregulators, indicating their relevance for PC research. The ING family consists of five protein-coding genes from ING1 to ING5 and pseudogene INGX. The ING genes were revealed through their sequence homology to the first identified ING1 from an in vivo screen. ING factors are a part of histone modification complexes. With the help of the conserved plant homeodomain (PHD) motif, ING factors bind to Histone 3 Lysine 4 (H3K4) methylation mark with a stronger affinity to the highest methylation grade H3K4me3 and recruit histone acetyltransferases (HAT) and histone deacetylases (HDAC) to chromatin. ING1 and ING2 are core subunits of mSIN3a-HDAC corepressor complexes, whereas ING3–5 interact with different HAT complexes that serve as coactivators. ING members belong to type II tumour suppressors and are frequently downregulated in many types of malignancies, including PC. As the family name indicates, ING proteins are able to inhibit cell growth and tumour development via regulation of cell cycle and cancer-relevant pathways such as apoptosis, cellular senescence, DNA repair, cell migration, invasion, and angiogenesis. Many ING splice variants that enhance the diversity of ING activity were discovered. However, it seems that the existence of multiple ING splice variants is underestimated, since alternative splice variants, such as the AR coregulators ING1 and ING3, counteract full-length ING and thus play an opposite functional role. These results open a novel prospective investigation direction in understanding ING factors biology in PC and other malignancies.
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Affiliation(s)
| | - Aria Baniahmad
- Correspondence: ; Tel.: +49-3641-9396-820; Fax: +49-3641-9396-822
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A Novel Splice Variant of the Inhibitor of Growth 3 Lacks the Plant Homeodomain and Regulates Epithelial-Mesenchymal Transition in Prostate Cancer Cells. Biomolecules 2021; 11:biom11081152. [PMID: 34439818 PMCID: PMC8392754 DOI: 10.3390/biom11081152] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/14/2022] Open
Abstract
Inhibitor of growth 3 (ING3) is one of five members of the ING tumour suppressor family, characterized by a highly conserved plant homeodomain (PHD) as a reader of the histone mark H3K4me3. ING3 was reported to act as a tumour suppressor in many different cancer types to regulate apoptosis. On the other hand, ING3 levels positively correlate with poor survival prognosis of prostate cancer (PCa) patients. In PCa cells, ING3 acts rather as an androgen receptor (AR) co-activator and harbours oncogenic properties in PCa. Here, we show the identification of a novel ING3 splice variant in both the human PCa cell line LNCaP and in human PCa patient specimen. The novel ING3 splice variant lacks exon 11, ING3∆ex11, which results in deletion of the PHD, providing a unique opportunity to analyse functionally the PHD of ING3 by a natural splice variant. Functionally, overexpression of ING3Δex11 induced morphological changes of LNCaP-derived 3D spheroids with generation of lumen and pore-like structures within spheroids. Since these structures are an indicator of epithelial-mesenchymal transition (EMT), key regulatory factors and markers for EMT were analysed. The data suggest that in contrast to ING3, ING3Δex11 specifically modulates the expression of key EMT-regulating upstream transcription factors and induces the expression of EMT markers, indicating that the PHD of ING3 inhibits EMT. In line with this, ING3 knockdown also induced the expression of EMT markers, confirming the impact of ING3 on EMT regulation. Further, ING3 knockdown induced cellular senescence via a pathway leading to cell cycle arrest, indicating an oncogenic role for ING3 in PCa. Thus, the data suggest that the ING3Δex11 splice variant lacking functional PHD exhibits oncogenic characteristics through triggering EMT in PCa cells.
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5
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Li X, Zhang Q, Zhang M, Luo Y, Fu Y. Downregulation of nuclear ING3 expression and translocalization to cytoplasm promotes tumorigenesis and progression in head and neck squamous cell carcinoma (HNSCC). Histol Histopathol 2019; 35:681-690. [PMID: 31886514 DOI: 10.14670/hh-18-197] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
ING3 (inhibitor of growth gene 3) is a member of the ING gene family, and is considered as a candidate tumor suppressor gene. In order to explore the roles of ING3 in tumorigenesis and cancer progression of head and neck squamous cell carcinoma (HNSCC), ING3 expression was assessed in 173 cases of HNSCC by immunohistochemistry. The expression of ING3 was also compared to clinicopathological variables, and the expression of several tumorigenic markers. Nuclear expression of ING3 in HNSCC was significantly lower than that in dysplasia and normal epithelium, and was negatively correlated with a poor-differentiated status, T staging and TNM staging. In contrast, cytoplasmic expression of ING3 was significantly increased in HNSCC, and was statistically associated with lymph node metastasis and 14-3-3η expression. In addition, nuclear expression of ING3 was positively correlated with the expression of p300, p21 and acetylated p53. In conclusion, decreases in nuclear ING3 may play important roles in tumorigenesis, progression and tumor differentiation in HNSCC. Increases in cytoplasmic ING3 may be due to 14-3-3η binding and may also be involved in malignant progression. Nuclear ING3 may modulate the transactivation of target genes, promoting apoptosis through interactions with p300 and p21. Moreover, ING3 may interact with p300 to upregulate the level of acetylation of p53, and promote p53-mediated cell cycle arrest, senescence and/or apoptosis. Therefore, ING3 may be a potential tumor suppressor and a possible therapeutic target in HNSCC.
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Affiliation(s)
- Xiaohan Li
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, China.
| | - Qun Zhang
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Mingming Zhang
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yusong Luo
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yaping Fu
- Department of Pathology, Shengjing Hospital of China Medical University, Shenyang, China
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6
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Mouche A, Archambeau J, Ricordel C, Chaillot L, Bigot N, Guillaudeux T, Grenon M, Pedeux R. ING3 is required for ATM signaling and DNA repair in response to DNA double strand breaks. Cell Death Differ 2019; 26:2344-2357. [PMID: 30804473 DOI: 10.1038/s41418-019-0305-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 12/21/2018] [Accepted: 01/28/2019] [Indexed: 01/16/2023] Open
Abstract
Inhibitor of Growth 3 (ING3) is a candidate tumor suppressor gene whose expression is lost in tumors such as hepatocellular carcinoma, head and neck squamous cell carcinoma and melanoma. In the present study, we show that ING3-depleted human cells and yeast cells deleted for its ortholog YNG2 are sensitive to DNA damage suggesting a conserved role in response to such stress. In human cells, ING3 is recruited to DNA double strand breaks and is required for ATM activation. Remarkably, in response to doxorubicin, ATM activation is dependent on ING3 but not on TIP60, whose recruitment to DNA breaks also depends on ING3. These events lead to ATM-mediated phosphorylation of NBS1 and the subsequent recruitment of RNF8, RNF168, 53BP1, and BRCA1, which are major mediators of the DNA damage response. Accordingly, upon genotoxic stress, DNA repair by non-homologous end joining (NHEJ) or homologous recombination (HR) were impaired in absence of ING3. Finally, immunoglobulin class switch recombination (CSR), a physiological mechanism requiring NHEJ repair, was impaired in the absence of ING3. Since deregulation of DNA double strand break repair is associated with genomic instability, we propose a novel function of ING3 as a caretaker tumor suppressor involved in the DNA damage signaling and repair.
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Affiliation(s)
- Audrey Mouche
- INSERM U1242, Chemistry Oncogenesis Stress and Signaling, CLCC Eugène Marquis, Rennes, France.,Université de Rennes 1, Rennes, France.,INSERM U1236, MICMAC, Rennes, France
| | - Jérôme Archambeau
- INSERM U1242, Chemistry Oncogenesis Stress and Signaling, CLCC Eugène Marquis, Rennes, France.,Université de Rennes 1, Rennes, France
| | - Charles Ricordel
- INSERM U1242, Chemistry Oncogenesis Stress and Signaling, CLCC Eugène Marquis, Rennes, France.,Université de Rennes 1, Rennes, France
| | - Laura Chaillot
- INSERM U1242, Chemistry Oncogenesis Stress and Signaling, CLCC Eugène Marquis, Rennes, France.,Université de Rennes 1, Rennes, France.,UMS Biosit, SFR Biologie-Santé, Rennes, France
| | - Nicolas Bigot
- Université de Rennes 1, Rennes, France.,INSERM U1236, MICMAC, Rennes, France.,Genome Damage and Stability Centre, University of Sussex, Falmer, Brighton, BN1 9RQ, UK
| | - Thierry Guillaudeux
- INSERM U1242, Chemistry Oncogenesis Stress and Signaling, CLCC Eugène Marquis, Rennes, France.,Université de Rennes 1, Rennes, France.,UMS Biosit, SFR Biologie-Santé, Rennes, France
| | - Muriel Grenon
- Biochemistry, School of Natural Sciences, National University of Ireland, Galway, Ireland
| | - Rémy Pedeux
- INSERM U1242, Chemistry Oncogenesis Stress and Signaling, CLCC Eugène Marquis, Rennes, France. .,Université de Rennes 1, Rennes, France.
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7
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Regulat-INGs in tumors and diseases: Focus on ncRNAs. Cancer Lett 2019; 447:66-74. [PMID: 30673590 DOI: 10.1016/j.canlet.2019.01.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/21/2018] [Accepted: 01/08/2019] [Indexed: 12/11/2022]
Abstract
ING family genes (Inhibitor of Growth) are tumor suppressor genes that play a vital role in cell homeostasis. It has been shown that their expression is lost or diminished in many cancers and other diseases. The main mechanisms by which they are regulated in oncogenesis have not yet been fully elucidated. The involvement of non-coding RNAs (ncRNAs) and in particular microRNAs (miRNAs) in post-transcriptional gene regulation is well established. miRNAs are short sequences (18-25 nucleotides) that can bind to the 3 'UTR sequence of the targeted messenger RNA (mRNA), leading to its degradation or translational repression. Interactions between the ING family and miRNAs have been described in some cancers but also in other diseases. The involvement of miRNAs in ING family regulation opens up new fields of investigation, particularly for targeted therapies. In this review, we will summarize the regulatory mechanisms at the RNA and protein level of the ING family and focus on the interactions with ncRNAs.
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8
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Inhibitor of growth 3 induces cell death by regulating cell proliferation, apoptosis and cell cycle arrest by blocking the PI3K/AKT pathway. Cancer Gene Ther 2018; 25:240-247. [DOI: 10.1038/s41417-018-0023-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 03/18/2018] [Accepted: 03/24/2018] [Indexed: 12/14/2022]
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9
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Zhang Z, Fu C, Xu Q, Wei X. Long non-coding RNA CASC7 inhibits the proliferation and migration of colon cancer cells via inhibiting microRNA-21. Biomed Pharmacother 2017; 95:1644-1653. [DOI: 10.1016/j.biopha.2017.09.052] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/10/2017] [Accepted: 09/10/2017] [Indexed: 10/18/2022] Open
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10
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Gou WF, Yang XF, Shen DF, Zhao S, Sun HZ, Luo JS, Zheng HC. Immunohistochemical profile of ING3 protein in normal and cancerous tissues. Oncol Lett 2017; 13:1631-1636. [PMID: 28454301 PMCID: PMC5403501 DOI: 10.3892/ol.2017.5632] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 12/14/2015] [Indexed: 12/14/2022] Open
Abstract
The inhibitor of growth family, member 3 (ING3) protein may be capable of blocking the cell cycle via activating p53-transactivated promoters of p21 and Bcl2-associated X protein, and may induce apoptosis via a Fas/caspase-8-dependent signaling pathway. In the present study, immunohistochemistry was performed in order to characterize the expression profile of ING3 protein in tissue microarrays containing mouse and human normal tissue, human hepatocellular (n=62), renal clear cell (n=62), pancreatic (n=62), esophageal squamous cell (n=45), cervical squamous cell (n=31), breast (n=144), gastric (n=196), colorectal (n=96), ovarian (n=208), endometrial (n=96) and lung carcinoma (n=192). In mouse tissue, ING3 protein was positively detected in the cytoplasm of cardiomyocytes, kidney and skeletal muscle cells, and was additionally detected in the cytoplasm and nucleus of bronchial and alveolar epithelium, gastric and intestinal gland, and mammary gland cells. In human tissues, ING3 protein was principally distributed in the cytoplasm, but was observed in the cytoplasm and nucleus of tongue, esophagus, stomach, intestine, lung, skin, appendix, bladder, cervix and breast cells. ING3 immunoreactivity was strongly detected in the stomach, skin and cervical tissues, whereas a weak signal was detected in the cerebellum, brain stem, thymus, liver, skeletal muscle, testis and prostate. In total, ING3-positive specimens were identified in 424 of 1,194 tested cancer entities (35.5%). In a number of cases, ING3 expression was observed to be restricted to the cytoplasm and nucleus, excluding the cytoplasmic distribution identified in breast and hepatocellular carcinoma. Among these cases, ING3 was more frequently expressed in breast and gynecological types of cancer, including ovarian (59.2%), endometrial (47.9%), breast (38.9%) and cervical (35.5%) cancer. ING3-positive cases were more rare in renal clear cell (17.7%), hepatocellular (16.1%) and esophageal carcinoma (17.8%). It is suggested that ING3 may be involved in the repair and regeneration of organs or tissues, and may be closely associated with gynecological carcinogenesis.
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Affiliation(s)
- Wen-Feng Gou
- Cancer Center, The First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121001, P.R. China
| | - Xue-Feng Yang
- Cancer Center, The First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121001, P.R. China
| | - Dao-Fu Shen
- Cancer Center, The First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121001, P.R. China
| | - Shuang Zhao
- Cancer Center, The First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121001, P.R. China
| | - Hong-Zhi Sun
- Cancer Center, The First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121001, P.R. China
| | - Jun-Sheng Luo
- Key Laboratory of Brain and Spinal Cord Injury of Liaoning Province, The First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121001, P.R. China
| | - Hua-Chuan Zheng
- Cancer Center, The First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121001, P.R. China.,Key Laboratory of Brain and Spinal Cord Injury of Liaoning Province, The First Affiliated Hospital of Liaoning Medical University, Jinzhou, Liaoning 121001, P.R. China
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11
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Yang C, Gao J, Yan N, Wu B, Ren Y, Li H, Liang J. Propofol inhibits the growth and survival of gastric cancer cells in vitro through the upregulation of ING3. Oncol Rep 2016; 37:587-593. [DOI: 10.3892/or.2016.5218] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 06/17/2016] [Indexed: 12/28/2022] Open
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12
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Ma Y, Cheng X, Wang F, Pan J, Liu J, Chen H, Wang Y, Cai L. ING4 Inhibits Proliferation and Induces Apoptosis in Human Melanoma A375 Cells via the Fas/Caspase-8 Apoptosis Pathway. Dermatology 2016; 232:265-72. [DOI: 10.1159/000444050] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 01/06/2016] [Indexed: 11/19/2022] Open
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13
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Ubels JL, Glupker CD, Schotanus MP, Haarsma LD. Involvement of the extrinsic and intrinsic pathways in ultraviolet B-induced apoptosis of corneal epithelial cells. Exp Eye Res 2015; 145:26-35. [PMID: 26559338 DOI: 10.1016/j.exer.2015.11.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/26/2015] [Accepted: 11/03/2015] [Indexed: 01/19/2023]
Abstract
The goal of this study was to elucidate the pathway by which UVB initiates efflux of K(+) and subsequently apoptosis in human corneal limbal epithelial (HCLE) cells. The initial focus of the study was on the extrinsic pathway involving Fas. HCLE cells transfected with Fas siRNA were exposed to 80-150 mJ/cm(2) UVB and incubated in culture medium with 5.5 mM K(+). Knockdown of Fas resulted in limited reduction in UVB-induced caspase-8 and -3 activity. Patch-clamp recordings showed no difference in UVB-induced normalized K(+) currents between Fas transfected and control cells. Knockdown of caspase-8 had no effect on the activation of caspase-3 following UVB exposure, while a caspase-8 inhibitor completely eliminated UVB activation of caspase-3. This suggests that caspase-8 is a robust enzyme, able to activate caspase-3 via residual caspase-8 present after knockdown, and that caspase-8 is directly involved in the UVB activation of caspase-3. Inhibition of caspase-9 significantly decreased the activation of caspases-8 and -3 in response to UVB. Knockdown of Apaf-1, required for activation of caspase-9, resulted in a significant reduction in UVB-induced activation of caspases-9, -8, and -3. Knockdown of Apaf-1 also inhibited intrinsic and UVB-induced levels of apoptosis, as determined by DNA fragmentation measured by TUNEL assay. In UVB exposed cultures treated with caspase-3 inhibitor, the percentage of apoptotic cells was reduced to control levels, confirming the necessity of caspase-3 activation in DNA fragmentation. The lack of effect of Fas knockdown on K(+) channel activation, as well as the limited effect on activation of caspases-8 and -3, strongly suggest that Fas and the extrinsic pathway is not of primary importance in the initiation of apoptosis in response to UVB in HCLE cells. Inhibition of caspase-8 and -3 activation following inhibition of caspase-9, as well as reduction in activation of caspases-9, -8, and -3 and DNA fragmentation in response to Apaf-1 knockdown support the conclusion that the intrinsic pathway is more important in UVB-induced apoptosis in HCLE cells.
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Affiliation(s)
- John L Ubels
- Department of Biology, Calvin College, Grand Rapids, MI, USA.
| | | | | | - Loren D Haarsma
- Department of Physics and Astronomy, Calvin College, Grand Rapids, MI, USA
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14
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Nabbi A, Almami A, Thakur S, Suzuki K, Boland D, Bismar TA, Riabowol K. ING3 protein expression profiling in normal human tissues suggest its role in cellular growth and self-renewal. Eur J Cell Biol 2015; 94:214-22. [PMID: 25819753 DOI: 10.1016/j.ejcb.2015.03.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Revised: 03/03/2015] [Accepted: 03/03/2015] [Indexed: 12/17/2022] Open
Abstract
Members of the INhibitor of Growth (ING) family of proteins act as readers of the epigenetic code through specific recognition of the trimethylated form of lysine 4 of histone H3 (H3K4Me3) by their plant homeodomains. The founding member of the family, ING1, was initially identified as a tumor suppressor with altered regulation in a variety of cancer types. While alterations in ING1 and ING4 levels have been reported in a variety of cancer types, little is known regarding ING3 protein levels in normal or transformed cells due to a lack of reliable immunological tools. In this study we present the characterization of a new monoclonal antibody we have developed against ING3 that specifically recognizes human and mouse ING3. The antibody works in western blots, immunofluorescence, immunoprecipitation and immunohistochemistry. Using this antibody we show that ING3 is most highly expressed in small intestine, bone marrow and epidermis, tissues in which cells undergo rapid proliferation and renewal. Consistent with this observation, we show that ING3 is expressed at significantly higher levels in proliferating versus quiescent epithelial cells. These data suggest that ING3 levels may serve as a surrogate for growth rate, and suggest possible roles for ING3 in growth and self renewal and related diseases such as cancer.
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Affiliation(s)
- Arash Nabbi
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Oncology, Southern Alberta Cancer Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Amal Almami
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Oncology, Southern Alberta Cancer Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Satbir Thakur
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Oncology, Southern Alberta Cancer Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Keiko Suzuki
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Oncology, Southern Alberta Cancer Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Donna Boland
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Oncology, Southern Alberta Cancer Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Tarek A Bismar
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Oncology, Southern Alberta Cancer Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Pathology & Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Karl Riabowol
- Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Department of Oncology, Southern Alberta Cancer Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
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15
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Defining the minimal peptide sequence of the ING1b tumour suppressor capable of efficiently inducing apoptosis. Cell Death Discov 2015; 1:15048. [PMID: 27551477 PMCID: PMC4979497 DOI: 10.1038/cddiscovery.2015.48] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 09/08/2015] [Indexed: 02/07/2023] Open
Abstract
The ING1b protein is a type-II tumour suppressor and stoichiometric member of the Sin3 histone deacetylase (HDAC) protein complex in which it acts to target HDAC activity to regulate chromatin structure. Altering ING1 levels by ectopic expression of ING1b in cancer cells promotes apoptosis, whereas altering levels by knockout in normal murine fibroblasts alters sensitivity to doxorubicin-induced apoptosis. We have identified a minimal region of ING1b capable of inducing levels of apoptosis in targeted cells as effectively as full-length ING1b, using transient overexpression of ING1b fragments followed by the Annexin V assay. We observed high levels of apoptosis in 14 of 14 cancer cell lines tested. Infecting triple-negative tumorigenic MDA-MB-468 breast cancer, U2OS or Saos-2 cells at multiplicities of infection (MOIs) ranging from 10 to 20 rapidly triggered apoptosis in ~80% of infected cells within 48 h. This was not due to the effects of virus, as infection at the same MOI with a control adenovirus expressing GFP was not effective in inducing apoptosis. When used at low MOIs, the ING1b fragment showed a cell-killing efficacy that was higher than native, full-length ING1b. Using a doxycycline-regulated inducible p53 expression system demonstrated that apoptosis induced by the ING1b fragment was p53 independent. Given the growing importance of combination therapies, we evaluated whether there was synergism between the ING1b fragment and HDAC inhibitors. Combination treatments with TSA, LBH 589 and SAHA reduced cancer cell survival by 3.9–4.7-fold as compared with single-drug treatment, and resulted in ~90% reduction in cell survival. Normalized isobologram analysis confirmed strong synergism between the ING1b fragment and drugs tested. These findings provide support for using ING1b-derived therapeutics as adjuvant treatments in combination with existing epigenetic therapies.
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16
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Rotte A, Li G, Bhandaru M. Tumor suppressor Ing1b facilitates DNA repair and prevents oxidative stress induced cell death. Apoptosis 2014; 19:518-26. [PMID: 24242916 DOI: 10.1007/s10495-013-0940-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Inhibitor of growth (ING) family of proteins are known to coordinate with histone acetyltransferases and regulate the key events of cell cycle and DNA repair. Previous work from our lab showed that Ing1b regulated the nucleotide excision repair by facilitating histone acetylation and subsequent chromatin relaxation. Further, it was also shown that Ing1b protected the cells from genomic instability induced cell death by promoting ubiquitination of proliferating cell nuclear antigen (PCNA). In the present study we explored the role of Ing1b in the repair of oxidized DNA and prevention of oxidative stress induced genotoxic cell death. Using HCT116 cells we show that Ing1b protein expression is induced by treatment with H2O2. Ing1b lacking cells showed decreased ability to repair the oxidized DNA. PCNA monoubiquitination, a critical event of DNA repair was blunted in Ing1b knock down cells and augmented in Ing1b over expressing cells. Moreover, oxidative stress induced cell death was higher in cells lacking Ing1b whereas it was lower in Ing1b over expressing cells. Finally we show that inhibition of histone deacetylases, rescued the Ing1b knock down cells from cytotoxic effects of H2O2 treatment.
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Affiliation(s)
- Anand Rotte
- Department of Dermatology and Skin Science, University of British Columbia, Research Pavilion, 828 West, 10th Avenue, Vancouver, BC, V5Z 1L8, Canada,
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17
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Hu GW, Yan XW, Qin YJ, Nie HT. Molecular cloning and expression analysis of inhibitor of growth protein 3 (ING3) in the Manila clam, Ruditapes philippinarum. Mol Biol Rep 2014; 41:3583-90. [PMID: 24566680 DOI: 10.1007/s11033-014-3221-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 01/28/2014] [Indexed: 11/27/2022]
Abstract
Inhibitor of growth protein 3 (ING3), a new member of ING family, is involved in the regulation of various processes. In this study, a full-length cDNA of ING3 (named as RpING3) was cloned from the gill of Ruditapes philippinarum by rapid amplification of cDNA ends method for the first time. The cDNA obtained was 1442 bp exclusive of poly (A) residues with a 1248 bp open reading frame encoding 415 amino acids. The RpING3 protein has a calculated molecular weight of 46.59 kDa and isoelectric point of 6.62. Two conserved motif and some functional sites were found. Tissue distribution analysis of the RpING3 mRNA revealed that the RpING3 expression level was much higher in gill and digestive gland while lower in mantle, foot and adductor muscle. The temporal expression of RpING3 in digestive gland after lead exposure was recorded by quantitative real-time PCR. The result showed that RpING3 was rapidly up-regulated at 6 h post-exposure and reached tenfold of the control group. These results suggest that RpING3 dependent signaling pathway is present in Manila clam and RpING3 may play important roles in protecting cells from heavy metal damage in R. philippinarum.
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Affiliation(s)
- Guang-Wei Hu
- Engineering and Technology Research Center of Shellfish Breeding in Liaoning Province, Dalian Ocean University, Dalian, 116023, China
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18
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Bhandaru M, Martinka M, Li G, Rotte A. Loss of XRCC1 confers a metastatic phenotype to melanoma cells and is associated with poor survival in patients with melanoma. Pigment Cell Melanoma Res 2014; 27:366-75. [DOI: 10.1111/pcmr.12212] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 01/07/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Madhuri Bhandaru
- Department of Dermatology and Skin Science; University of British Columbia; Vancouver BC Canada
| | - Magdalena Martinka
- Department of Pathology and Laboratory Medicine; University of British Columbia; Vancouver BC Canada
| | - Gang Li
- Department of Dermatology and Skin Science; University of British Columbia; Vancouver BC Canada
| | - Anand Rotte
- Department of Dermatology and Skin Science; University of British Columbia; Vancouver BC Canada
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19
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ING4 regulates JWA in angiogenesis and their prognostic value in melanoma patients. Br J Cancer 2013; 109:2842-52. [PMID: 24157826 PMCID: PMC3844917 DOI: 10.1038/bjc.2013.670] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/27/2013] [Accepted: 09/30/2013] [Indexed: 12/27/2022] Open
Abstract
Background: We previously showed that inhibitor of growth family member 4 (ING4) inhibits melanoma angiogenesis, and JWA suppresses the metastasis of melanoma cells. As angiogenesis is essential for tumour metastasis, further investigation of the function of ING4 and JWA in melanoma angiogenesis is needed, and their prognostic value are of great interest. Methods: Western blot, tube-formation assays and luciferase assays were used to investigate the correlation between ING4 and JWA in melanoma angiogenesis. JWA and integrin-linked kinase (ILK) expression was determined on a tissue microarray constructed from 175 biopsies. Results: ING4 promoted JWA expression by activating JWA promoter. Furthermore, the regulation of growth and tube formation of endothelial cells by ING4 was partially JWA dependent. Also, ING4 inhibited the ILK-induced angiogenesis signalling pathway via JWA. Moreover, reduced JWA, or increased ILK, expression was closely associated with 5-year disease-specific survival of melanoma patients (P=0.001 and 0.007, respectively). There was also a positive correlation between ING4 and JWA yet a negative correlation between ING4 and ILK. Importantly, their concomitant expressions were significantly related to 5-year survival of melanoma patients (P=0.002 and 0.003, respectively). Conclusion: JWA has an important role in ING4-regulated melanoma angiogenesis, and ING4/JWA/ILK are promising prognostic markers and may be used as anti-angiogenic therapeutic targets for melanoma.
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20
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Tang Y, Cheng Y, Martinka M, Ong CJ, Li G. Prognostic significance of KAI1/CD82 in human melanoma and its role in cell migration and invasion through the regulation of ING4. Carcinogenesis 2013; 35:86-95. [PMID: 24130172 DOI: 10.1093/carcin/bgt346] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
KAI1/CD82 is a member of the transmembrane 4 superfamily, which was first identified as a metastasis suppressor for prostate cancer. The expression of KAI1 was found to be reduced in many types of cancers, including prostate, breast, ovarian, cervical and endometrial cancer. However, the role of KAI1 in melanoma pathogenesis is not known. In this study, we investigated the expression level of KAI1 in a large set of melanocytic lesions at different stages. We found that the expression of KAI1 is significantly decreased during melanoma progression. In fact, KAI1 expression is drastically reduced in primary melanoma compared with dysplastic nevi (P = 1.8×10(-4)) and further reduced in metastatic melanoma compared with primary melanoma (P = 9.4 × 10(-15)). Furthermore, decreased KAI1 staining is strongly correlated with a worse 5 year and 10 year patient survival. Multivariate Cox regression analysis showed that KAI1 is also an independent prognostic factor for both 5 year and 10 year survival. Moreover, we found that overexpression of KAI1 significantly inhibited melanoma cell migration through suppression of Rho-associated kinase-mediated formation of stress fiber. Our data also suggested that overexpression of KAI1 significantly inhibited melanoma cell invasion by reducing the activity of metalloproteinase-2. In addition, we found that suppression of melanoma cell migration by KAI1 is mediated by another tumor-suppressor protein called inhibitor of growth 4 through the regulation of p65. Taken together, our data suggest that KAI1 may be used as a promising prognostic marker and a possible therapeutic target for human melanoma.
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Affiliation(s)
- Yun Tang
- Department of Dermatology and Skin Science
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21
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Li S, Fan T, Liu H, Chen J, Qin C, Ren X. Tumor suppressor ING4 overexpression contributes to proliferation and invasion inhibition in gastric carcinoma by suppressing the NF-κB signaling pathway. Mol Biol Rep 2013; 40:5723-32. [PMID: 24057236 DOI: 10.1007/s11033-013-2675-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Accepted: 09/14/2013] [Indexed: 12/26/2022]
Abstract
There is growing evidence that inhibitor of growth 4 (ING4) plays a pivotal role in development and progression of multiple different tumors; however, its precise function in gastric carcinoma remains to be elucidated. In the present study, we investigated ING4 level in gastric carcinoma tissues and cells, and preliminarily elucidated the role of ING4 in the proliferation and invasion of gastric carcinoma. The results demonstrated that expressions of ING4 mRNA and protein in gastric carcinoma tissues and cells were significantly lower than those in normal tissues and cells (P < 0.05). ING4 level in gastric carcinoma cells stably expressing ING4 was markedly higher than those in untreated group and empty vector pcDNA3.1 group (P < 0.05). Elevated ING4 level resulted in the inhibition of proliferation and invasion in three of gastric carcinoma cell lines MKN-28, SGC-7901 and MKN-45. Most notably, increased ING4 level evidently evoked the down-regulation of p65, p-IκBα, MMP-9 and uPA proteins and the up-regulation of IκBα protein. Our results presented herein suggest that ING4 level elevation mediated proliferation and invasion inhibition may be tightly associated with the suppression of NF-κB signaling pathway.
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Affiliation(s)
- Shijie Li
- Department of General Surgery, Huaihe Hospital of Henan University, No.8 Baogong Lake North Road, Kaifeng, 475000, Henan, People's Republic of China
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22
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Suzuki S, Nozawa Y, Tsukamoto S, Kaneko T, Imai H, Minami N. ING3 is essential for asymmetric cell division during mouse oocyte maturation. PLoS One 2013; 8:e74749. [PMID: 24066152 PMCID: PMC3774679 DOI: 10.1371/journal.pone.0074749] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 08/05/2013] [Indexed: 12/27/2022] Open
Abstract
ING3 (inhibitor of growth family, member 3) is a subunit of the nucleosome acetyltransferase of histone 4 (NuA4) complex, which activates gene expression. ING3, which contains a plant homeodomain (PHD) motif that can bind to trimethylated lysine 4 on histone H3 (H3K4me3), is ubiquitously expressed in mammalian tissues and governs transcriptional regulation, cell cycle control, and apoptosis via p53-mediated transcription or the Fas/caspase-8 pathway. Thus, ING3 plays a number of important roles in various somatic cells. However, the role(s) of ING3 in germ cells remains unknown. Here, we show that loss of ING3 function led to the failure of asymmetric cell division and cortical reorganization in the mouse oocyte. Immunostaining showed that in fully grown germinal vesicle (GV) oocytes, ING3 localized predominantly in the GV. After germinal vesicle breakdown (GVBD), ING3 homogeneously localized in the cytoplasm. In oocytes where Ing3 was targeted by siRNA microinjection, we observed symmetric cell division during mouse oocyte maturation. In those oocytes, oocyte polarization was not established due to the failure to form an actin cap or a cortical granule-free domain (CGFD), the lack of which inhibited spindle migration. These features were among the main causes of abnormal symmetric cell division. Interestingly, an analysis of the mRNA expression levels of genes related to asymmetric cell division revealed that only mTOR was downregulated, and, furthermore, that genes downstream of mTOR (e.g., Cdc42, Rac1, and RhoA) were also downregulated in siIng3-injected oocytes. Therefore, ING3 may regulate asymmetric cell division through the mTOR pathway during mouse oocyte maturation.
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Affiliation(s)
- Shinnosuke Suzuki
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Yusuke Nozawa
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Satoshi Tsukamoto
- Laboratory Animal and Genome Sciences Section, National Institute of Radiological Sciences, Chiba, Japan
| | - Takehito Kaneko
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroshi Imai
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Naojiro Minami
- Laboratory of Reproductive Biology, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
- * E-mail:
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23
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p90 RSK2 mediates antianoikis signals by both transcription-dependent and -independent mechanisms. Mol Cell Biol 2013; 33:2574-85. [PMID: 23608533 DOI: 10.1128/mcb.01677-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
How invasive and metastatic tumor cells evade anoikis induction remains unclear. We found that knockdown of RSK2 sensitizes diverse cancer cells to anoikis induction, which is mediated through phosphorylation targets including apoptosis signal-regulating kinase 1 (ASK1) and cyclic AMP (cAMP) response element-binding protein (CREB). We provide evidence to show that RSK2 inhibits ASK1 by phosphorylating S83, T1109, and T1326 through a novel mechanism in which phospho-T1109/T1326 inhibits ATP binding to ASK1, while phospho-S83 attenuates ASK1 substrate MKK6 binding. Moreover, the RSK2→CREB signaling pathway provides antianoikis protection by regulating gene expression of protein effectors that are involved in cell death regulation, including the antiapoptotic factor protein tyrosine kinase 6 (PTK6) and the proapoptotic factor inhibitor-of-growth protein 3 (ING3). PTK6 overexpression or ING3 knockdown in addition to ASK1 knockdown further rescued the increased sensitivity to anoikis induction in RSK2 knockdown cells. These data together suggest that RSK2 functions as a signal integrator to provide antianoikis protection to cancer cells in both transcription-independent and -dependent manners, in part by signaling through ASK1 and CREB, and contributes to cancer cell invasion and tumor metastasis.
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24
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Prognostic significance of Fbw7 in human melanoma and its role in cell migration. J Invest Dermatol 2013; 133:1794-802. [PMID: 23381582 DOI: 10.1038/jid.2013.58] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The E3 ubiquitin ligase Fbw7 (F-box and WD repeat domain-containing 7) is broadly considered as a tumor suppressor because of its role in the turnover of several well-known oncoproteins. However, the role of Fbw7 in melanomagenesis is not clear. To investigate the expression profile and biological functions of Fbw7 in melanoma, we examined Fbw7 expression level using melanoma tissue microarray and immunohistochemistry. Our data showed that Fbw7 expression is significantly reduced in primary melanoma compared with dysplastic nevi (P=0.020) and further reduced in metastatic melanoma compared with primary melanoma (P=0.011). Furthermore, we observed a strong correlation between negative Fbw7 expression and a worse 5-year survival of melanoma patients (P=0.015). We also found that both Fbw7 protein and mRNA expression was significantly reduced in nine melanoma cell lines compared with normal melanocytes. Moreover, our in vitro studies showed a remarkable increase of cell migration and stress fiber formation in Fbw7 knockdown cells, and treatment of selective MEK (MAPK/ERK kinase) inhibitor abrogated Fbw7α knockdown-induced melanoma cell migration. Taken together, our findings indicate that Fbw7 has an important role in melanoma progression, and it inhibits melanoma cell migration through the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling pathway and may serve as a prognostic marker.
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25
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Zhang L, Wang Y, Zhang F, Wang Y, Zhang Q. Correlation between tumor suppressor inhibitor of growth family member 4 expression and microvessel density in breast cancer. Hum Pathol 2012; 43:1611-7. [DOI: 10.1016/j.humpath.2011.11.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 11/17/2011] [Accepted: 11/18/2011] [Indexed: 10/28/2022]
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26
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Jafarnejad SM, Li G. Regulation of p53 by ING family members in suppression of tumor initiation and progression. Cancer Metastasis Rev 2012; 31:55-73. [PMID: 22095030 DOI: 10.1007/s10555-011-9329-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The INhibitor of Growth (ING) family is an evolutionarily conserved set of proteins, implicated in suppression of initiation and progression of cancers in various tissues. They promote cell cycle arrest, cellular senescence and apoptosis, participate in stress responses, regulate DNA replication and DNA damage responses, and inhibit cancer cell migration, invasion, and angiogenesis of the tumors. At the molecular level, ING proteins are believed to participate in chromatin remodeling and transcriptional regulation of their target genes. However, the best known function of ING proteins is their cooperation with p53 tumor suppressor protein in tumor suppression. All major isoforms of ING family members can promote the transactivition of p53 and the majority of them are shown to directly interact with p53. In addition, ING proteins are thought to interact with and modulate the function of auxiliary members of p53 pathway, such as MDM2, ARF , p300, and p21, indicating their widespread involvement in the regulation and function of this prominent tumor suppressor pathway. It seems that p53 pathway is the main mechanism by which ING proteins exert their functions. Nevertheless, regulation of other pathways which are not relevant to p53, yet important for tumorigenesis such as TGF-β and NF-κB, by ING proteins is also observed. This review summarizes the current understanding of the mutual interactions and cooperation between different members of ING family with p53 pathway and implications of this cooperation in the suppression of cancer initiation and progression.
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Affiliation(s)
- Seyed Mehdi Jafarnejad
- Department of Dermatology and Skin Science, University of British Columbia, Vancouver, BC, Canada
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27
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Jafarnejad SM, Ardekani GS, Ghaffari M, Martinka M, Li G. Sox4-mediated Dicer expression is critical for suppression of melanoma cell invasion. Oncogene 2012; 32:2131-9. [PMID: 22689055 PMCID: PMC5025280 DOI: 10.1038/onc.2012.239] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We previously reported reduced expression of Sox4 in metastatic melanoma and its role in suppression of cell migration and invasion through inhibition of NF-κB p50. Sox4 can also bind to the promoter sequence of Dicer, a miRNA biogenesis factor. Interestingly, altered expression of Dicer was also observed in cancers. However, the potential mechanisms which regulate Dicer expression and its potential significance in melanoma progression are unknown. Here we studied the regulation of Dicer expression by Sox4 and its role in suppression of melanoma invasion. Our data showed that Sox4 positively regulates Dicer expression by binding to its promoter sequences and enhancing its activity. We found that knockdown of Dicer enhances the matrigel invasion of melanoma cells by at least 2-fold. In addition, we revealed that overexpression of exogenous Dicer reverts the enhanced melanoma cell invasion upon Sox4 knockdown. Furthermore, we examined the expression of Dicer protein in a large set of melanocytic lesions (n=504) at different stages by tissue microarray and found that Dicer expression is inversely correlated with melanoma progression (P < 0.0001). Consistently, reduced Dicer expression was correlated with a poorer overall and disease-specific 5-year survival of patients (P = 0.015 and 0.0029, respectively). In addition, we found a significant correlation between expression of Sox4 and Dicer proteins in melanoma biopsies (P = 0.009), further indicating the regulation of Dicer expression by Sox4. Finally, we revealed that knockdown of Sox4 induces a major change in the expression pattern of miRNAs in melanoma cells, mainly due to reduced expression of Dicer. Our results pinpoint the regulation of Dicer expression by Sox4 in melanoma and the critical role of Dicer in suppression of melanoma invasion. Our findings on Sox4 regulated miRNA biogenesis pathway may aid toward the development of novel targeted therapeutic approaches for melanoma.
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Affiliation(s)
- S M Jafarnejad
- Department of Dermatology and Skin Science, Jack Bell Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
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28
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Wei Q, He W, Lu Y, Yao J, Cao X. Effect of the tumor suppressor gene ING4 on the proliferation of MCF-7 human breast cancer cells. Oncol Lett 2012; 4:438-442. [PMID: 22970041 DOI: 10.3892/ol.2012.744] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Accepted: 05/28/2012] [Indexed: 01/15/2023] Open
Abstract
Inhibitor of growth 4 (ING4) is a member of the ING family and acts as a tumor suppressor protein. To investigate the impact of ING4 on breast cancer proliferation, the present study examined the antitumor effects caused by upregulation in the expression of ING4 and its possible mechanism of effect in MCF-7 cells. A plasmid-based expression system encoding the ING4 gene was used to construct a stable cell line and overexpress ING4 in MCF-7 cells. Real-time PCR and western blot analysis were used to detect the mRNA and protein expression levels of ING4, respectively. Cell growth was examined by methylthiazolyltetrazolium (MTT) assay. Cell cycle distribution and cell apoptosis were measured by flow cytometry. The expression of p21, p53 and bax genes were tested by real-time PCR and western blot analysis. The stably transfected cell lines pcDNA3.1(+)/ING4 (with the ING4 gene) and pcDNA3.1(+) (an empty vector) were established. The expression levels of ING4 mRNA and protein in the stable cell line expressing pcDNA3.1(+)/ING4 were significantly higher than those of the two control cell lines. The cell proliferation of stably transfected cells was inhibited, and the inhibitory rate was 62.58±2.93%. Based on the changes in cell cycle distribution in stably transfected cells compared with two control cell lines, a number of cells were blocked in the G0/G1 phase 67.82±3.78% (P<0.05). In addition, the apoptotic rate was significantly higher, at 31.51±3.02% (P<0.05). Real-time PCR revealed that p21 and bax mRNA expression were increased (P<0.01), but the expression of p53 did not change significantly (P>0.05) in the stably transfected cell lines. Western blot analysis results of p21, bax and p53 were in accordance with real-time PCR results. ING4 upregulation may inhibit breast cancer cell proliferation and accelerate the process of apoptosis. It is suggested that ING4 plays a significant role in the suppression of breast cancer progression.
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Affiliation(s)
- Qinjun Wei
- Department of Biotechnology, Nanjing Medical University, Nanjing 210029, P.R. China
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29
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Lu M, Chen F, Wang Q, Wang K, Pan Q, Zhang X. Downregulation of inhibitor of growth 3 is correlated with tumorigenesis and progression of hepatocellular carcinoma. Oncol Lett 2012; 4:47-52. [PMID: 22807958 DOI: 10.3892/ol.2012.685] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Accepted: 03/30/2012] [Indexed: 11/06/2022] Open
Abstract
ING3, a member of the inhibitor of growth (ING) family, has been reported to be involved in transcription modulation, cell cycle control and the induction of apoptosis. Previous studies have demonstrated that the expression of ING3 decreased in melanoma and head and neck squamous cell carcinoma (HNSCC). The aim of this study was to investigate the role of ING3 in hepatocellular carcinoma (HCC) tumorigenesis and progression. The correlation between ING3 expression and clinicopathological variables of HCC was analyzed. Using the real-time reverse transcription-polymerase chain reaction (RT-PCR), it was found that ING3 was downregulated in HCC tissues compared with adjacent non-cancerous tissues (p<0.05). The immunohistochemical staining of tissue microarray data indicated a significant reduction of ING3 expression in 57.14% of HCC cases (64/112). In addition, the downregulation of ING3 was associated with the tumor differentiation stage. Most HCC samples of Edmondson-Steiner grades II to III exhibited inhibition of ING3 expression. The overexpression of ING3 in HCC cells was found to suppress cell proliferation, colony formation and cell migration, suggesting that ING3 acts as a tumor suppressor in HCC cells. Taken together, the data revealed that ING3 may serve as a suppression factor during tumorigenesis and progression of HCC.
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Affiliation(s)
- Meiling Lu
- The Central Laboratory, People's 10th Hospital, Shanghai 200072
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30
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Yang HY, Liu HL, Tian LT, Song RP, Song X, Yin DL, Liang YJ, Qu LD, Jiang HC, Liu JR, Liu LX. Expression and prognostic value of ING3 in human primary hepatocellular carcinoma. Exp Biol Med (Maywood) 2012; 237:352-61. [PMID: 22550337 DOI: 10.1258/ebm.2011.011346] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The tumor-suppressor ING3 has been shown to be involved in tumor transcriptional regulation, apoptosis and the cell cycle. Some studies have demonstrated that ING3 is dysregulated in several types of cancers. However, the expression and function of ING3 in human hepatocellular carcinoma (HCC) remains unclear. The aim of this study is to investigate ING3 expression in hepatic tumors and its clinical relevance in hepatic cancer. The expression of ING3 protein was examined in 120 dissected HCC tissues and 47 liver tissues adjacent to the tumor by immunohistochemical assays and confirmed by Western blot analysis in 20 paired frozen tumor and non-tumor liver tissues. The relationship between ING3 staining and clinico-pathological characteristics of HCC was further analyzed. The mRNA expression of ING3 in the dissected tissues was also analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and realtime PCR. Both mRNA and protein concentrations of ING3 were found to be downregulated in the majority of HCC tumors in comparison with matched non-tumor hepatic tissues. Analysis of the relationship between ING3 staining and clinico-pathological characteristics of HCC showed that the low expression of ING3 protein is correlated with more aggressive behavior of the tumor. Kaplan–Meier curves demonstrated that patients with a low expression of ING3 have a significantly increased risk of shortened survival time. In addition, multivariate analysis suggested that the level of ING3 expression may be an independent prognostic factor. Our findings indicate that ING3 may be an important marker for human hepatocellular carcinoma progression and prognosis, as well as a potential therapeutic target.
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Affiliation(s)
- Hai-Yan Yang
- Department of Hepatic Surgery, The First Affiliated Hospital of Harbin Medical University, Key Laboratory of Hepatosplenic Surgery, Ministry of Education
| | - Hao-Ling Liu
- Department of Endocrinology, The First Clinical College of Harbin Medical University, 23 Youzheng Street, Nangang District
| | - Lan-Tian Tian
- Department of Hepatic Surgery, The First Affiliated Hospital of Harbin Medical University, Key Laboratory of Hepatosplenic Surgery, Ministry of Education
| | - Rui-Peng Song
- Department of Hepatic Surgery, The First Affiliated Hospital of Harbin Medical University, Key Laboratory of Hepatosplenic Surgery, Ministry of Education
| | - Xuan Song
- Department of Hepatic Surgery, The First Affiliated Hospital of Harbin Medical University, Key Laboratory of Hepatosplenic Surgery, Ministry of Education
| | - Da-Long Yin
- Department of Hepatic Surgery, The First Affiliated Hospital of Harbin Medical University, Key Laboratory of Hepatosplenic Surgery, Ministry of Education
| | - Ying-Jian Liang
- Department of Hepatic Surgery, The First Affiliated Hospital of Harbin Medical University, Key Laboratory of Hepatosplenic Surgery, Ministry of Education
| | - Lian-Dong Qu
- National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Experimental Animal Center, 427 Ma Duan Street, Harbin 150001, PR China
| | - Hong-Chi Jiang
- Department of Hepatic Surgery, The First Affiliated Hospital of Harbin Medical University, Key Laboratory of Hepatosplenic Surgery, Ministry of Education
| | - Jia-Ren Liu
- Harvard Medical School, 300 Longwood Ave, Boston, MA 02115, USA
| | - Lian-Xin Liu
- Department of Hepatic Surgery, The First Affiliated Hospital of Harbin Medical University, Key Laboratory of Hepatosplenic Surgery, Ministry of Education
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Liu Y, Yu L, Wang Y, Zhang Y, Wang Y, Zhang G. Expression of tumor suppressor gene ING4 in ovarian carcinoma is correlated with microvessel density. J Cancer Res Clin Oncol 2012; 138:647-55. [PMID: 22228137 DOI: 10.1007/s00432-011-1099-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 11/08/2011] [Indexed: 01/19/2023]
Abstract
PURPOSE Angiogenesis, estimated by microvessel density (MVD), has been shown to predict poor progression-free survival in women with advanced epithelial ovarian cancer. Inhibitor of growth (ING) family proteins inhibit angiogenesis in a number of cancers. We evaluated the role of ING4 in regulation of angiogenesis in patients with epithelial ovarian cancer. METHODS Semi-quantitative RT-PCR was used to determine ING4 mRNA levels in 40 ovarian cancer patients and 40 normal controls. Also, we used immunohistochemistry to evaluate (1) ING4 protein expression levels and (2) the level of MVD by staining CD34, a microvessel marker, in these patients. Through statistical analysis, the possible correlation between the ING4 expression and angiogenesis was explored. RESULTS ING4 mRNA and protein were significantly downregulated in all ovarian cancer patients compared to normal controls (P < 0.001). Endometrioid carcinoma tissue had significantly lower ING4 levels compared to serous or mucinous ovarian cancer. ING4 expression correlated negatively with stage and histological grade of ovarian cancers. MVD correlated negatively with ING4 protein and mRNA levels (ρ = -0.865; P < 0.001 and ρ = -0.724; P < 0.001, respectively). CONCLUSIONS Loss of ING4 may promote microvessel formation and plays a role in facilitating the development of ovarian cancer. Although the specific mechanisms are not yet understood, our data suggest that ING4 may be a promising target for the treatment for ovarian cancer.
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Affiliation(s)
- Yinglan Liu
- Department of Obstetrics and Gynecology, First Affiliated Hospital of Harbin Medical University, Harbin, China
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32
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Mathema VB, Koh YS. Inhibitor of growth-4 mediates chromatin modification and has a suppressive effect on tumorigenesis and innate immunity. Tumour Biol 2011; 33:1-7. [PMID: 21971889 DOI: 10.1007/s13277-011-0249-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 09/23/2011] [Indexed: 10/17/2022] Open
Abstract
Inhibitor of growth-4 (ING4) is a member of the ING family and acts as a tumor suppressor protein. ING4 is a promising candidate for cancer research due to its anti-angiogenic function and its role in the inhibition of cell migration, cell cycle, and induction of apoptosis. Interaction of this protein with the histone acetyl transferase complex plays a vital role in the regulation of multiple nuclear factor kappa light chain enhancer of activated B cells response elements and thus in the regulation of innate immunity. Splice variants of ING4 have different binding affinities to target sites, which results in the enhancement of its functional diversity. ING4 is among the few known regulatory proteins that can directly interact with chromatin as well as with transcription factors. The influence of ING4 on tumor necrosis factor-α, keratinocyte chemoattractant, interleukin (IL)-6, IL-8, matrix metalloproteinases, cyclooxygenase-2, and IκBα expression clearly demonstrates its critical role in the regulation of inflammatory mediators. Its interaction with liprin α1 and p53 contribute to mitigate cell spreading and induce apoptosis of cancer cells. Multiple factors including breast cancer melanoma suppressor-1 are upstream regulators of ING4 and are frequently deactivated in tumor cells. In the present review, the different properties of ING4 are discussed, and its activities are correlated with different aspects of cell physiology. Special emphasis is placed on our current understanding of ING4 with respect to its influence on chromatin modification, tumorigenesis, and innate immunity.
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Affiliation(s)
- Vivek Bhakta Mathema
- Department of Microbiology and Immunology, School of Medicine, Jeju National University, 102 Jejudaehakno, Jeju 690-756, South Korea
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ING Genes Work as Tumor Suppressor Genes in the Carcinogenesis of Head and Neck Squamous Cell Carcinoma. JOURNAL OF ONCOLOGY 2010; 2011:963614. [PMID: 21052543 PMCID: PMC2968421 DOI: 10.1155/2011/963614] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Accepted: 10/01/2010] [Indexed: 12/24/2022]
Abstract
Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer in the world. The evolution and progression of HNSCC are considered to result from multiple stepwise alterations of cellular and molecular pathways in squamous epithelium. Recently, inhibitor of growth gene (ING) family consisting of five genes, ING1 to ING5, was identified as a new tumor suppressor gene family that was implicated in the downregulation of cell cycle and chromatin remodeling. In contrast, it has been shown that ING1 and ING2 play an oncogenic role in some cancers, this situation being similar to TGF-β. In HNSCC, the ING family has been reported to be downregulated, and ING translocation from the nucleus to the cytoplasm may be a critical event for carcinogenesis. In this paper, we describe our recent results and briefly summarize current knowledge regarding the biologic functions of ING in HNSCC.
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Jafarnejad SM, Wani AA, Martinka M, Li G. Prognostic significance of Sox4 expression in human cutaneous melanoma and its role in cell migration and invasion. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:2741-52. [PMID: 20952589 DOI: 10.2353/ajpath.2010.100377] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The Sox4 transcription factor is involved in various cellular processes, such as embryonic development and differentiation. Deregulated expression of Sox4 in several human cancers has been reported to date, but its role in melanoma is unknown. We explored the role of Sox4 in melanoma pathogenesis in vivo and in vitro. Using tissue microarray, we evaluated Sox4 expression in 180 melanocytic lesions and investigated its role in melanoma cell migration and invasion. Sox4 expression was remarkably reduced in metastatic melanoma compared with dysplastic nevi (P < 0.05) and primary melanoma (P < 0.01). This reduction was correlated with a poorer disease-specific survival of melanoma patients (P = 0.039). Multivariate Cox regression analysis revealed that reduced Sox4 expression is an independent prognostic factor (P = 0.049). Knockdown of Sox4 enhanced melanoma cell invasion, migration, and stress fiber formation. The increased migration and invasion on Sox4 knockdown depends on the presence of nuclear factor (NF)-κB p50 and is abrogated when p50 is knocked down. We further observed inhibition of NF-κB p50 transcription by Sox4, in addition to a reverse pattern of expression of Sox4 and NF-κB p50 in different stages of melanocytic lesions. Our results suggest that Sox4 regulates melanoma cell migration and invasion in an NF-κB p50-dependent manner and may serve as a prognostic marker and potential therapeutic target for human melanoma.
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Affiliation(s)
- Seyed Mehdi Jafarnejad
- Department of Dermatology and Skin Science, Vancouver Coastal Health Research Institute, University of British Columbia, Vancouver, British Columbia, Canada
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Lin H, Wong RPC, Martinka M, Li G. BRG1 expression is increased in human cutaneous melanoma. Br J Dermatol 2010; 163:502-10. [PMID: 20491765 DOI: 10.1111/j.1365-2133.2010.09851.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND The SWI/SNF chromatin remodelling complex plays important roles in cellular processes including cell differentiation, cell cycle control and DNA repair. Aberrant expression of SWI/SNF subunits is involved in cancer development. The core subunit of the SWI/SNF complex, SNF5, has been shown to be inactivated in malignant rhabdoid tumours and has been defined as a tumour suppressor. However, the role of the catalytic subunit, BRG1, is not well defined in cancer. OBJECTIVES To investigate the role of BRG1 in melanoma development, we examined the expression of BRG1 in melanocytic lesions at different stages and analysed the correlation between BRG1 expression and clinicopathological variables and patient survival. METHODS Using tissue microarray and immunohistochemistry, we evaluated BRG1 staining in 48 dysplastic naevi, 90 primary melanomas and 47 metastatic melanomas. We studied melanoma cell proliferative ability with reduced BRG1 expression by small interfering RNA using cell proliferation assay and cell cycle analysis. RESULTS We found that BRG1 expression was increased in primary melanoma and metastatic melanoma compared with dysplastic naevi (P<0·0001). We did not find any correlation between BRG1 expression and melanoma patient survival. In addition, we demonstrated that knockdown of BRG1 in melanoma cell lines resulted in significantly reduced cell proliferative ability. This reduced cell proliferation is due to G(1) phase arrest as cyclin D(1) is downregulated upon BRG1 knockdown. CONCLUSIONS Our data indicate that BRG1 is significantly increased in human melanoma and is involved in melanoma initiation.
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Affiliation(s)
- H Lin
- Department of Dermatology and Skin Science, Vancouver Coastal Health Research Institute, University of British Columbia, Vancouver, BC, Canada
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36
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Piche B, Li G. Inhibitor of growth tumor suppressors in cancer progression. Cell Mol Life Sci 2010; 67:1987-99. [PMID: 20195696 PMCID: PMC11115670 DOI: 10.1007/s00018-010-0312-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 01/11/2010] [Accepted: 01/29/2010] [Indexed: 12/27/2022]
Abstract
The inhibitor of growth (ING) family of tumor suppressors has five members and is implicated in the control of apoptosis, senescence, DNA repair, and cancer progression. However, little is known about ING activity in the regulation of cancer progression. ING members and splice variants seem to behave differently with respect to cancer invasion and metastasis. Interaction with histone trimethylated at lysine 4 (H3K4me3), hypoxia inducible factor-1 (HIF-1), p53, and nuclear factor kappa-B (NF-kappaB) are potential mechanisms by which ING members exert effects on invasion and metastasis. Subcellular mislocalization, rapid protein degradation, and to a lesser extent ING gene mutation are among the mechanisms responsible for inappropriate ING levels in cancer cells. The aim of this review is to summarize the different roles of ING family tumor suppressors in cancer progression and the molecular mechanisms involved.
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Affiliation(s)
- Brad Piche
- Department of Dermatology and Skin Science, Jack Bell Research Centre, Vancouver Coastal Health Research Institute, University of British Columbia, 2660 Oak Street, Vancouver, BC V6H 3Z6 Canada
| | - Gang Li
- Department of Dermatology and Skin Science, Jack Bell Research Centre, Vancouver Coastal Health Research Institute, University of British Columbia, 2660 Oak Street, Vancouver, BC V6H 3Z6 Canada
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Majerciak V, Kruhlak M, Dagur PK, McCoy JP, Zheng ZM. Caspase-7 cleavage of Kaposi sarcoma-associated herpesvirus ORF57 confers a cellular function against viral lytic gene expression. J Biol Chem 2010; 285:11297-307. [PMID: 20159985 DOI: 10.1074/jbc.m109.068221] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Kaposi sarcoma-associated herpesvirus (KSHV) ORF57 is a viral early protein essential for KSHV multiplication. We found that B cells derived from cavity-based B cell lymphoma with lytic KSHV infection display activation of caspase-8 and cleavage of ORF57 in the cytoplasm by caspase-7 at the aspartate residue at position 33 from the N terminus. Caspase-7 cleavage of ORF57 is prevented by pan-caspase inhibitor z-VAD, caspase-3 and caspase-7 inhibitor z-DEVD, and caspase-7 small interfering RNAs. The caspase-7 cleavage site (30)DETD(33) in ORF57 is not cleavable by caspase-3, although both enzymes use DEXD as a common cleavage site. B cells with lytic KSHV infection and caspase-7 activation exhibited a greatly reduced level of ORF57. A majority of the cells expressing active caspase-7 appeared to have no detectable ORF57 and vice versa. Upon cleavage with caspase-7, ORF57 was deficient in promoting the expression of viral lytic genes. Inhibiting caspase-7 cleavage of ORF57 in KSHV(+) BCBL-1 cells by z-VAD, z-DEVD, or caspase-7 small interfering RNA led to increased expression of viral lytic genes and production of cell-free virus particles. Collectively, our data provide the first compelling evidence that caspase cleavage of ORF57 may represent a cellular function against lytic KSHV infection.
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Affiliation(s)
- Vladimir Majerciak
- HIV and AIDS Malignancy Branch, National Institutes of Health, Bethesda, Maryland 20892, USA
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Chen G, Wang Y, Garate M, Zhou J, Li G. The tumor suppressor ING3 is degraded by SCFSkp2-mediated ubiquitin–proteasome system. Oncogene 2009; 29:1498-508. [DOI: 10.1038/onc.2009.424] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Lin H, Wong RPC, Martinka M, Li G. Loss of SNF5 expression correlates with poor patient survival in melanoma. Clin Cancer Res 2009; 15:6404-11. [PMID: 19808872 DOI: 10.1158/1078-0432.ccr-09-1135] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Aberrant expression of SWI/SNF chromatin remodeling complex is involved in cancer development. The tumor suppressor SNF5, the core subunit of SWI/SNF complex, has been shown to regulate cell differentiation, cell cycle control, and apoptosis. To investigate the role of SNF5 in the development of melanoma, we examined the expression of SNF5 in melanocytic lesions at different stages and analyzed the correlation between SNF5 expression and clinicopathologic variables and patient survival. EXPERIMENTAL DESIGN Using tissue microarray and immunohistochemistry, we evaluated SNF5 staining in 51 dysplastic nevi, 88 primary melanomas, and 48 metastatic melanomas. We studied chemosensitivity of melanoma cells with reduced SNF5 expression by siRNA using cell survival and apoptosis assays. RESULTS SNF5 expression was reduced in metastatic melanoma compared with dysplastic nevi (P = 0.005), in advanced primary melanoma (Clark's level V) compared with low risk Clark's level II melanoma (P = 0.019), and in melanoma at sun-exposed sites compared with sun-protected sites (P = 0.044). Furthermore, we showed a strong correlation between negative SNF5 expression and a worse 5-year survival in melanoma patients (P = 0.016). Multivariate Cox regression analysis revealed that negative SNF5 expression is an independent prognostic factor to predict patient outcome in primary melanomas (P = 0.031). Finally, we showed that knockdown of SNF5 in melanoma cell lines resulted in significant chemoresistance. CONCLUSIONS Our data indicate that SNF5 may be an important marker for human melanoma progression and prognosis as well as a potential therapeutic target.
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Affiliation(s)
- Hanyang Lin
- Department of Dermatology, Vancouver Coastal Health Research Institute, University of British Columbia, Vancouver, BC, Canada
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Abstract
Recent emerging evidence suggests that ING family proteins play roles in carcinogenesis both as oncogenes and tumor suppressor genes depending on the family members and on cell status. Previous results from non-physiologic overexpression experiments showed that all five family members induce apoptosis or cell cycle arrest, thus it had been thought until very recently that all of the family members function as tumor suppressor genes. Therefore restoration of ING family proteins in cancer cells has been proposed as a treatment for cancers. However, ING2 knockdown experiments showed unexpected results: ING2 knockdown led to senescence in normal human fibroblast cells and suppressed cancer cell growth. ING2 is also overexpressed in colorectal cancer, and promotes cancer cell invasion through an MMP13 dependent pathway. Additionally, it was reported that ING2 has two isoforms, ING2a and ING2b. Although expression of ING2a predominates compared with ING2b, both isoforms confer resistance against cell cycle arrest or apoptosis to cancer cells, thus knockdown of both isoforms is critical to remove this resistance. Taken together, these results suggest that ING2 can function as an oncogene in some specific types of cancer cells, indicating restoration of this gene in cancer cells could cause cancer progression. Because knockdown of ING2 suppresses cancer cell invasion and induces apoptosis or cell cycle arrest, ING2 may be an anticancer drug target. In this brief review, we discuss possible clinical applications of ING2 with the latest knowledge of molecular targeted therapies.
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Affiliation(s)
- M Unoki
- Laboratory for Biomarker, The Institute of Physical and Chemical Research, RIKEN, Tokyo 108-8639, Japan
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Champagne KS, Kutateladze TG. Structural insight into histone recognition by the ING PHD fingers. Curr Drug Targets 2009; 10:432-41. [PMID: 19442115 DOI: 10.2174/138945009788185040] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The Inhibitor of Growth (ING) tumor suppressors are implicated in oncogenesis, control of DNA damage repair, cellular senescence and apoptosis. All members of the ING family contain unique amino-terminal regions and a carboxy-terminal plant homeodomain (PHD) finger. While the amino-terminal domains associate with a number of protein effectors including distinct components of histone deacetylase (HDAC) and histone acetyltransferase (HAT) complexes, the PHD finger binds strongly and specifically to histone H3 trimethylated at lysine 4 (H3K4me3). In this review we describe the molecular mechanism of H3K4me3 recognition by the ING1-5 PHD fingers, analyze the determinants of the histone specificity and compare the biological activities and structures within subsets of PHD fingers. The atomic-resolution structures of the ING PHD fingers in complex with a H3K4me3 peptide reveal that the histone tail is bound in a large and deep binding site encompassing nearly one-third of the protein surface. An extensive network of intermolecular hydrogen bonds, hydrophobic and cation-pi contacts, and complementary surface interactions coordinate the first six residues of the H3K4me3 peptide. The trimethylated Lys4 occupies an elongated groove, formed by the highly conserved aromatic and hydrophobic residues of the PHD finger, whereas the adjacent groove accommodates Arg2. The two grooves are connected by a narrow channel, the small size of which defines the PHD finger's specificity, excluding interactions with other modified histone peptides. Binding of the ING PHD fingers to H3K4me3 plays a critical role in regulating chromatin acetylation. The ING proteins function as tethering molecules that physically link the HDAC and HAT enzymatic complexes to chromatin. In this review we also highlight progress recently made in understanding the molecular basis underlying biological and tumorigenic activities of the ING tumor suppressors.
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Affiliation(s)
- Karen S Champagne
- Department of Pharmacology, University of Colorado Denver School of Medicine, Aurora, Colorado 80045, USA.
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Shah S, Smith H, Feng X, Rancourt DE, Riabowol K. ING function in apoptosis in diverse model systems. Biochem Cell Biol 2009; 87:117-25. [PMID: 19234528 DOI: 10.1139/o08-107] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Genetic studies in model organisms have shown that programmed cell death (apoptosis) plays a significant role during development, where a deficiency in apoptosis results in severe and diverse diseases. Dysregulation of apoptosis also contributes to a variety of human diseases, such as cancer and autoimmune diseases. ING family proteins (ING1-ING5) are involved in many cellular processes, and appear to play a significant role in apoptosis. Loss or downregulation of ING protein function is frequently observed in different tumour types, many of which are resistant to apoptosis, thus warranting their classification as type II tumour suppressors. Several different in vitro and in vivo models have explored the role of ING proteins in regulating apoptosis. In this review, we discuss the progress that has been made in understanding ING protein function in apoptosis using in vitro studies and Mus musculus, Xenopus laevis, and Caenorhabditis elegans experimental models, with an emphasis on ING1 and ING3.
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Affiliation(s)
- Sitar Shah
- Southern Alberta Cancer Research Institute, Department of Biochemistry & Molecular Biology, Faculty of Medicine, University of Calgary, 3330 Hospital Dr. NW, Calgary, ABT2N4N1, Canada
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Unoki M, Kumamoto K, Takenoshita S, Harris CC. Reviewing the current classification of inhibitor of growth family proteins. Cancer Sci 2009; 100:1173-9. [PMID: 19432890 DOI: 10.1111/j.1349-7006.2009.01183.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Inhibitor of growth (ING) family proteins have been defined as candidate tumor suppressors for more than a decade. Recent emerging results using siRNA and knockout mice are expanding the previous understanding of this protein family. The results of ING1 knockout mouse experiments revealed that ING1 has a protective effect on apoptosis. Our recent results showed that ING2 is overexpressed in colorectal cancer, and induces colon cancer cell invasion through an MMP13-dependent pathway. Knockdown of ING2 by siRNA induces premature senescence in normal human fibroblast cells, and apoptosis or cell cycle arrest in various adherent cancer cells. Taken together, these results suggest that ING2 may also have roles in cancer progression and/or malignant transformation under some conditions. Additionally, knockdown of ING4 and ING5 by siRNA shows an inhibitory effect on the transition from G(2)/M to G(1) phase and DNA replication, respectively, suggesting that these proteins may play roles during cell proliferation in some context. ING family proteins may play dual roles, similar to transforming growth factor-beta, which has tumor suppressor-like functions in normal epithelium and also oncogenic functions in invasive metastatic cancers. In the present article, we briefly review ING history and propose a possible interpretation of discrepancies between past and recent data.
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Affiliation(s)
- Motoko Unoki
- Laboratory for Biomarker, The Institute of Physical and Chemical Research, RIKEN, Tokyo, Japan
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Inhibitor of growth 4 is involved in melanomagenesis and induces growth suppression and apoptosis in melanoma cell line M14. Melanoma Res 2009; 19:1-7. [DOI: 10.1097/cmr.0b013e32831bc42f] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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45
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Karst AM, Gao K, Nelson CC, Li G. Nuclear factor kappa B subunit p50 promotes melanoma angiogenesis by upregulating interleukin-6 expression. Int J Cancer 2009; 124:494-501. [DOI: 10.1002/ijc.23973] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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46
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Li C, Zhao H, Hu Z, Liu Z, Wang LE, Gershenwald JE, Prieto VG, Lee JE, Duvic M, Grimm EA, Wei Q. Genetic variants and haplotypes of the caspase-8 and caspase-10 genes contribute to susceptibility to cutaneous melanoma. Hum Mutat 2009; 29:1443-51. [PMID: 18563783 DOI: 10.1002/humu.20803] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Caspase-8 (CASP8) and caspase-10 (CASP10) play key roles in regulating apoptosis, and their functional polymorphisms may alter apoptosis and cancer risk. However, no reported studies have investigated the association between such polymorphisms and the risk of cutaneous melanoma (CM). In a hospital-based study of 805 non-Hispanic white patients with CM and 835 cancer-free age-, sex-, and ethnicity-matched controls, we genotyped three reported putatively functional polymorphisms of CASP8 and CASP10-CASP8 D302 H (rs1045485:G>C), CASP8 -652 6N del (rs3834129:-/CTTACT), and CASP10 I522L (rs13006529:A>T)-and assessed their associations with risk of CM and interactions with known risk factors for CM. We also calculated the false-positive report probability (FPRP) for significant findings. CASP8 302 H variant genotypes (DH: adjusted odds ratio [OR], 0.70; 95% confidence interval [CI], 0.50-0.98; DH+HH: unadjusted OR, 0.78; 95% CI, 0.62-0.98; FPRP, 0.79) and CASP8 -652 6N del variant genotypes (ins/del: OR, 0.74; 95% CI, 0.57-0.97; ins/del+del/del: OR, 0.76; 95% CI, 0.61-0.95; FPRP, 0.61) were associated with significantly lower CM risk than were the DD and ins/ins genotypes, respectively. However, the CASP10 522L variant genotypes were not associated with significantly altered CM risk. Also, the D-del-I haplotype was associated with a significantly lower CM risk (OR, 0.52; 95% CI, 0.37-0.74; FPRP, 0.04) than was the most common haplotype, D-ins-I. Furthermore, multivariate logistic regression analysis revealed that CASP8 D302 H, CASP8 -652 6N del, and CASP10 I522L were independent risk factors for CM. Therefore, these CASP8 and CASP10 polymorphisms may be biomarkers for susceptibility to CM.
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Affiliation(s)
- Chunying Li
- Department of Epidemiology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA
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COLES ANDREWH, JONES STEPHENN. The ING gene family in the regulation of cell growth and tumorigenesis. J Cell Physiol 2009; 218:45-57. [PMID: 18780289 PMCID: PMC2872195 DOI: 10.1002/jcp.21583] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The five members of the inhibitor of growth (ING) gene family have garnered significant interest due to their putative roles as tumor suppressors. However, the precise role(s) of these ING proteins in regulating cell growth and tumorigenesis remains uncertain. Biochemical and molecular biological analysis has revealed that all ING members encode a PHD finger motif proposed to bind methylated histones and phosphoinosital, and all ING proteins have been found as components of large chromatin remodeling complexes that also include histone acetyl transferase (HAT) and histone deacetylase (HDAC) enzymes, suggesting a role for ING proteins in regulating gene transcription. Additionally, the results of forced overexpression studies performed in tissue culture have indicated that several of the ING proteins can interact with the p53 tumor suppressor protein and/or the nuclear factor-kappa B (NF-kappaB) protein complex. As these ING-associated proteins play well-established roles in numerous cell processes, including DNA repair, cell growth and survival, inflammation, and tumor suppression, several models have been proposed that ING proteins act as key regulators of cell growth not only through their ability to modify gene transcription but also through their ability to alter p53 and NF-kappaB activity. However, these models have yet to be substantiated by in vivo experimentation. This review summarizes what is currently known about the biological functions of the five ING genes based upon in vitro experiments and recent mouse modeling efforts, and will highlight the potential impact of INGs on the development of cancer.
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Affiliation(s)
- ANDREW H. COLES
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - STEPHEN N. JONES
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts
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The Caenorhabditis elegans ing-3 gene regulates ionizing radiation-induced germ-cell apoptosis in a p53-associated pathway. Genetics 2008; 181:473-82. [PMID: 19015549 DOI: 10.1534/genetics.107.080515] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The inhibitor of growth (ING) family of type II tumor suppressors are encoded by five genes in mammals and by three genes in Caenorhabditis elegans. All ING proteins contain a highly conserved plant homeodomain (PHD) zinc finger. ING proteins are activated by stresses, including ionizing radiation, leading to the activation of p53. ING proteins in mammals and yeast have recently been shown to read the histone code in a methylation-sensitive manner to regulate gene expression. Here we identify and characterize ing-3, the C. elegans gene with the highest sequence identity to the human ING3 gene. ING-3 colocalizes with chromatin in embryos, the germline, and somatic cells. The ing-3 gene is part of an operon but is also transcribed from its own promoter. Both ing-3(RNAi) and ing-3 mutant strains demonstrate that the gene likely functions in concert with the C. elegans p53 homolog, cep-1, to induce germ-cell apoptosis in response to ionizing radiation. Somatically, the ing-3 mutant has a weak kinker uncoordinated (kinker Unc) phenotype, indicating a possible neuronal function.
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Borkosky SS, Gunduz M, Nagatsuka H, Beder LB, Gunduz E, Ali MALS, Rodriguez AP, Cilek MZ, Tominaga S, Yamanaka N, Shimizu K, Nagai N. Frequent deletion of ING2 locus at 4q35.1 associates with advanced tumor stage in head and neck squamous cell carcinoma. J Cancer Res Clin Oncol 2008; 135:703-13. [PMID: 18998165 DOI: 10.1007/s00432-008-0507-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Accepted: 10/20/2008] [Indexed: 10/21/2022]
Abstract
BACKGROUND Loss of heterozygosity (LOH) in the ING family members has been shown in head and neck squamous cell carcinoma (HNSCC) except for ING2. Like all the other members of ING family, ING2, which is located at chromosome 4q35.1, is a promising tumor suppressor gene (TSG). In this study, we performed LOH analysis of ING2 in HNSCC and compared it with clinicopathological variables. MATERIALS AND METHODS We performed LOH analysis in DNAs from 80 paired of normal and HNSCC tissues, using a specifically designed microsatellite marker on chromosome 4q35.1, which detects allelic loss of ING2. TP53 mutation analysis and its relationship with ING2 chromosomal deletion were also performed in available 68 of the samples. The correlation between LOH status and clinicopathological characteristics was evaluated by using statistical methods. The overall survival (OS) and disease free survival (DFS) were also determined. RESULTS LOH was detected in 54.6% (30/55) of the informative samples. Statistical significance was obtained between LOH and tumor (T) stage (P = 0.02), application of radiotherapy and chemotherapy. Positive node status (N) appeared to be the only independent prognostic factor for both OS (P = 0.031) and DFS (P = 0.044). CONCLUSIONS Our study showed allelic loss of 4q35.1 in HNSCC. The high percentage of LOH suggests ING2 as a candidate TSG in HNSCC. High LOH frequency was statistically associated with advanced T stage, suggesting that ING2 LOH might occur in late stages during HNSCC progression.
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Affiliation(s)
- Silvia S Borkosky
- Department of Oral Pathology and Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikatacho, Okayama, Japan
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Patra SK, Szyf M. DNA methylation-mediated nucleosome dynamics and oncogenic Ras signaling: insights from FAS, FAS ligand and RASSF1A. FEBS J 2008; 275:5217-35. [PMID: 18803665 DOI: 10.1111/j.1742-4658.2008.06658.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cytosine methylation at the 5-carbon position is the only known stable base modification found in the mammalian genome. The organization and modification of chromatin is a key factor in programming gene expression patterns. Recent findings suggest that DNA methylation at the junction of transcription initiation and elongation plays a critical role in suppression of transcription. This effect is mechanistically mediated by the state of chromatin modification. DNA methylation attracts binding of methyl-CpG-binding domain proteins that trigger repression of transcription, whereas DNA demethylation facilitates transcription activation. Understanding the rules that guide differential gene expression, as well as transcription dynamics and transcript abundance, has proven to be a taxing problem for molecular biologists and oncologists alike. The use of novel molecular modeling methods is providing exciting insights into the challenging problem of how methylation mediates chromatin dynamics. New data implicate lipid rafts as the coordinators of signals emanating from the cell membrane and are converging on the mechanisms linking DNA methylation and chromatin dynamics. This review focuses on some of these recent advances and uses lipid-raft-facilitated Ras signaling as a paradigm for understanding DNA methylation, chromatin dynamics and apoptosis.
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