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Tsubaki M, Takeda T, Obata N, Kawashima K, Tabata M, Imano M, Satou T, Nishida S. Combination therapy with dacarbazine and statins improved the survival rate in mice with metastatic melanoma. J Cell Physiol 2019; 234:17975-17989. [PMID: 30834527 DOI: 10.1002/jcp.28430] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 02/04/2019] [Accepted: 02/14/2019] [Indexed: 12/13/2022]
Abstract
Malignant melanoma is a highly aggressive skin cancer, and the overall median survival in patients with metastatic melanoma is only 6-9 months. Although molecular targeted therapies have recently been developed and have improved the overall survival, melanoma patients may show no response and acquisition of resistance to these drugs. Thus, other molecular approaches are essential for the treatment of metastatic melanoma. In the present study, we investigated the effect of cotreatment with dacarbazine and statins on tumor growth, metastasis, and survival rate in mice with metastatic melanomas. We found that cotreatment with dacarbazine and statins significantly inhibited tumor growth and metastasis via suppression of the RhoA/RhoC/LIM domain kinase/serum response factor/c-Fos pathway and enhanced p53, p21, p27, cleaved caspase-3, and cleaved poly(ADP-ribose) polymerase 1 expression in vivo. Moreover, the cotreatment significantly improved the survival rate in metastasis-bearing mice. Importantly, treatment with dacarbazine plus 100 mg/kg simvastatin or fluvastatin prevented metastasis-associated death in 4/20 mice that received dacarbazine + simvastatin and in 8/20 mice that received dacarbazine + fluvastatin (survival rates, 20% and 40%, respectively). These results suggested that cotreatment with dacarbazine and statins may thus serve as a new therapeutic approach to control tumor growth and metastasis in melanoma patients.
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Affiliation(s)
- Masanobu Tsubaki
- Division of Pharmacotherapy, Kindai University Faculty of Pharmacy, Kowakae, Higoshi-Osaka, Osaka, Japan
| | - Tomoya Takeda
- Division of Pharmacotherapy, Kindai University Faculty of Pharmacy, Kowakae, Higoshi-Osaka, Osaka, Japan
| | - Naoya Obata
- Division of Pharmacotherapy, Kindai University Faculty of Pharmacy, Kowakae, Higoshi-Osaka, Osaka, Japan
| | - Keishi Kawashima
- Division of Pharmacotherapy, Kindai University Faculty of Pharmacy, Kowakae, Higoshi-Osaka, Osaka, Japan
| | - Mitsuki Tabata
- Division of Pharmacotherapy, Kindai University Faculty of Pharmacy, Kowakae, Higoshi-Osaka, Osaka, Japan
| | - Motohiro Imano
- Department of Surgery, Kindai University Faculty of Medicine, Osakasayama, Osaka, Japan
| | - Takao Satou
- Department of Pathology, Kindai University Faculty of Medicine, Osakasayama, Osaka, Japan
| | - Shozo Nishida
- Division of Pharmacotherapy, Kindai University Faculty of Pharmacy, Kowakae, Higoshi-Osaka, Osaka, Japan
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Sun MY, Zhang H, Tao J, Ni ZH, Wu QX, Tang QF. Expression and biological function of rhotekin in gastric cancer through regulating p53 pathway. Cancer Manag Res 2019; 11:1069-1080. [PMID: 30774435 PMCID: PMC6354689 DOI: 10.2147/cmar.s185345] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Background/aim Gastric cancer (GC) is one of a most threatening cancer globally. Rhotekin (RTKN), a Rho effector, has been reported to be upregulated in GC tissues. This study aimed to investigate the underlying regulatory roles of RTKN in the biological behavior of GC. Methods Real-time PCR and Western blotting were carried out to detect the mRNA and protein expression, respectively. Cell Counting Kit-8 and xenograft nude mice model were used to evaluate cell proliferation. Flow cytometry analysis was performed to assess cell cycle distribution and cell apoptosis. Results RTKN had high expression level in GC compared with normal tissues. RTKN expression strongly associated with tumor size, TNM stage, lymphnode metastasis and the poor prognosis of patients with GC. Downregulation of RTKN significantly repressed GC cell proliferation, but increased cell population in G1/S phase and induced cell apoptosis. Moreover, the RTKN expression level was related to the p53 signaling pathway and histone deacetylase (HDAC) Class I pathway. RTKN knockdown caused a notable increment in the acetylation level of p53 (Lys382), and the expression of p53-target genes (p21, Bax, and PUMA), as well as a reduction in the expression of a potential deacetylase for p53, HDAC1. Notably, downregulation of HDAC1 had similar effects as RTKN knockdown, and RTKN overexpression could hardly abrogate the effects of HDAC1 knockdown on GC cells. Conclusion RTKN could work as an oncogene via regulating HDAC1/p53 and may become a promising treatment strategy for GC.
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Affiliation(s)
- Meng-Yao Sun
- Department of Clinical Laboratory and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China,
| | - Hong Zhang
- Center for Innovative Chinese Medicine Research, Institute of Interdisciplinary Medical Sciences, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Jie Tao
- Department of Clinical Laboratory and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China,
| | - Zhen-Hua Ni
- Department of Clinical Laboratory and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China,
| | - Qiu-Xue Wu
- Department of Clinical Laboratory and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China,
| | - Qing-Feng Tang
- Department of Clinical Laboratory and Central Laboratory, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 200062, China,
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Functions of Rhotekin, an Effector of Rho GTPase, and Its Binding Partners in Mammals. Int J Mol Sci 2018; 19:ijms19072121. [PMID: 30037057 PMCID: PMC6073136 DOI: 10.3390/ijms19072121] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 07/13/2018] [Accepted: 07/17/2018] [Indexed: 12/26/2022] Open
Abstract
Rhotekin is an effector protein for small GTPase Rho. This protein consists of a Rho binding domain (RBD), a pleckstrin homology (PH) domain, two proline-rich regions and a C-terminal PDZ (PSD-95, Discs-large, and ZO-1)-binding motif. We, and other groups, have identified various binding partners for Rhotekin and carried out biochemical and cell biological characterization. However, the physiological functions of Rhotekin, per se, are as of yet largely unknown. In this review, we summarize known features of Rhotekin and its binding partners in neuronal tissues and cancer cells.
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Zhou J, Zhang Y, Qi Y, Yu D, Shao Q, Liang J. MicroRNA-152 inhibits tumor cell growth by directly targeting RTKN in hepatocellular carcinoma. Oncol Rep 2016; 37:1227-1234. [PMID: 27922690 DOI: 10.3892/or.2016.5290] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 10/31/2016] [Indexed: 11/05/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the most common form of adult liver cancer and accounts for approximately 90% of all cases of primary liver cancer annually. Rhotekin (RTKN), which functions as a cancer promoter, can be frequently detected in many human cancers, including gastric cancer, colorectal carcinoma and bladder carcinoma. The aim of this study was to investigate the role of RTKN in HCC. Using HCC cells and tissues from patients with liver cancer, we demonstrated that RTKN was significantly increased in HCC. To examine the effect of RTKN on HCC, RTKN overexpressed or silenced HepG2 and Hep3B cells were constructed. Cell proliferation and apoptosis were measured by RT-PCR and flow cytometry. The results showed that RTKN can function as an oncogene and promote the proliferation, while inhibiting apoptosis, of HepG2 and Hep3B cells. Furthermore, we identified that RTKN is a direct gene target of miR-152. miR-152 can reverse the growth promoting effect of RTKN on HCC cells through G2/M phase arrest and nuclear factor-κB (NF-κB) signal inhibition. In conclusion, our research identified that miRNA-152 can inhibit tumor cell growth by targeting RTKN in HCC.
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Affiliation(s)
- Jiejing Zhou
- Department of Radiotherapy, Tangdu Hospital, The 4th Military Medical University, Xi'an, Shaanxi 710038, P.R. China
| | - Yanjun Zhang
- Department of Radiotherapy, Tangdu Hospital, The 4th Military Medical University, Xi'an, Shaanxi 710038, P.R. China
| | - Yuhong Qi
- Department of Radiotherapy, Tangdu Hospital, The 4th Military Medical University, Xi'an, Shaanxi 710038, P.R. China
| | - Dequan Yu
- Department of Radiotherapy, Tangdu Hospital, The 4th Military Medical University, Xi'an, Shaanxi 710038, P.R. China
| | - Qiuju Shao
- Department of Radiotherapy, Tangdu Hospital, The 4th Military Medical University, Xi'an, Shaanxi 710038, P.R. China
| | - Jun Liang
- Department of Radiotherapy, Tangdu Hospital, The 4th Military Medical University, Xi'an, Shaanxi 710038, P.R. China
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Wei W, Chen H, Liu S. Knockdown of Rhotekin 2 expression suppresses proliferation and invasion and induces apoptosis in hepatocellular carcinoma cells. Mol Med Rep 2016; 13:4865-71. [PMID: 27081789 DOI: 10.3892/mmr.2016.5113] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 12/03/2015] [Indexed: 11/05/2022] Open
Abstract
Hepatocellular carcinoma (HCC), which is one of the most common types of cancer worldwide, has been ranked as the third leading cause of cancer‑associated mortality worldwide. Rhotekin 2 (RTKN2), a Rho‑guanosine triphosphatase (GTPase) effector, has been reported to be anti‑apoptotic. However, the molecular mechanism underlying the biological function of RTKN2 in HCC is poorly defined. The current study reported that RTKN2 was overexpressed in 83% of HCC specimens compared with adjacent noncancerous tissues (n=30). Depletion of RTKN2 in HCC cells, HepG2 and BEL‑7404 by RNA interference led to marked inhibition of cell proliferation and cell cycle progression. Notably, RTKN2 silencing significantly reduced the levels of cell cycle‑associated proteins, proliferating cell nuclear antigen and cyclin‑dependent kinase 1. Additionally, it was identified that downregulation of RTKN2 in HCC cells notably induced cell apoptosis, while significantly repressing cell invasion. These data suggest that RTKN2 may act as an oncogene and inhibition of RTKN2 may be part of a novel therapeutic strategy for targeted HCC therapy.
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Affiliation(s)
- Wei Wei
- Department of Radiology, Jingzhou Central Hospital, Jingzhou, Hubei 434020, P.R. China
| | - Huabing Chen
- Department of Radiology, Jingzhou Central Hospital, Jingzhou, Hubei 434020, P.R. China
| | - Sibin Liu
- Department of Radiology, Jingzhou Central Hospital, Jingzhou, Hubei 434020, P.R. China
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Zhang W, Liang Z, Li J. Inhibition of rhotekin exhibits antitumor effects in lung cancer cells. Oncol Rep 2016; 35:2529-34. [PMID: 26935528 PMCID: PMC4811395 DOI: 10.3892/or.2016.4634] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 11/04/2015] [Indexed: 02/06/2023] Open
Abstract
Lung cancer is the leading cause for cancer-related death, however, the pathogenesis mechanism is poorly understood. Although the rhotekin (RTKN) gene has been reported to encode an effector for the Rho protein that has critical roles in regulating cell growth, the role of RTKN in lung cancer has not been investigated. In clinical lung cancer patient tumor samples, we identified that the RTKN gene expression level was significantly higher in tumor tissues compared to that of the adjacent normal tissues. To investigate the molecular mechanisms of RTKN in lung cancer, we established RTKN stable knock-down A549 and SPC-A-1 lung adenocarcinoma cell lines using lentiviral transfection of RTKN shRNA and evaluated the antitumor effects. The results showed that RTKN knock-down inhibited lung adenocarcinoma cell viability, induced S phase arrest and increased cell apoptosis. In addition, RTKN knock-down inhibited lung cancer cell invasion and adhesion. Further analysis showed that the S phase promoting factors cyclin-dependent kinase (CDK)1 and CDK2 levels were decreased in RTKN knock-down cells, and that the DNA replication initiation complex proteins Minichromosome maintenance protein complex (MCM)2 and MCM6 were decreased as well in RTKN knock-down cells. These results indicated that the RTKN protein was associated with lung cancer in clinic samples and exerted anticancer activity in lung adenocarcinoma cells through inhibiting cell cycle progression and the DNA replication machinery. These findings suggest that RTKN inhibition may be a novel therapeutic strategy for lung adenocarcinoma.
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Affiliation(s)
- Weizhen Zhang
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
| | - Zhenyu Liang
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
| | - Jing Li
- Department of Respiratory and Critical Care Medicine, Chronic Airways Diseases Laboratory, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China
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Qu GQ, Lu YM, Liu YF, Liu Y, Chen WX, Liao XH, Kong WM. Effect of RTKN on progression and metastasis of colon cancer in vitro. Biomed Pharmacother 2015; 74:117-23. [DOI: 10.1016/j.biopha.2015.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 07/20/2015] [Indexed: 12/30/2022] Open
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Loss of PTPRM associates with the pathogenic development of colorectal adenoma-carcinoma sequence. Sci Rep 2015; 5:9633. [PMID: 25910225 PMCID: PMC5386118 DOI: 10.1038/srep09633] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 03/10/2015] [Indexed: 11/09/2022] Open
Abstract
Identification and functional analysis of genes from genetically altered chromosomal regions would suggest new molecular targets for cancer diagnosis and treatment. Here we performed a genome-wide analysis of chromosomal copy number alterations (CNAs) in matching sets of colon mucosa-adenoma-carcinoma samples using high-throughput oligonucleotide microarray analysis. In silico analysis of NCBI GEO and TCGA datasets allowed us to uncover the significantly altered genes (p ≤ 0.001) associated with the identified CNAs. We performed quantitative PCR analysis of the genomic and complementary DNA derived from primary mucosa, adenoma, and carcinoma samples, and confirmed the recurrent loss and down-regulation of PTPRM in colon adenomas and carcinomas. Functional characterization demonstrated that PTPRM negatively regulates cell growth and colony formation, whereas loss of PTPRM promotes oncogenic cell growth. We further showed that, in accordance to Knudson's two-hit hypothesis, inactivation of PTPRM in colon cancer was mainly attributed to loss of heterozygosity and promoter hypermethylation. Taken together, this study demonstrates a putative tumor suppressive role for PTPRM and that genetic and epigenetic alterations of PTPRM may contribute to early step of colorectal tumorigenesis.
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Coupling S100A4 to Rhotekin alters Rho signaling output in breast cancer cells. Oncogene 2012; 32:3754-64. [PMID: 22964635 PMCID: PMC3525797 DOI: 10.1038/onc.2012.383] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Revised: 07/09/2012] [Accepted: 07/13/2012] [Indexed: 02/07/2023]
Abstract
Rho signaling is increasingly recognized to contribute to invasion and metastasis. In this study, we discovered that metastasis-associated protein S100A4 interacts with the Rho-binding domain (RBD) of Rhotekin, thus connecting S100A4 to the Rho pathway. Glutathione S-transferase pull-down and immunoprecipitation assays demonstrated that S100A4 specifically and directly binds to Rhotekin RBD, but not the other Rho effector RBDs. S100A4 binding to Rhotekin is calcium-dependent and uses residues distinct from those bound by active Rho. Interestingly, we found that S100A4 and Rhotekin can form a complex with active RhoA. Using RNA interference, we determined that suppression of both S100A4 and Rhotekin leads to loss of Rho-dependent membrane ruffling in response to epidermal growth factor, an increase in contractile F-actin 'stress' fibers and blocks invasive growth in three-dimensional culture. Accordingly, our data suggest that interaction of S100A4 and Rhotekin permits S100A4 to complex with RhoA and switch Rho function from stress fiber formation to membrane ruffling to confer an invasive phenotype.
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Iwai T, Saitoh A, Yamada M, Takahashi K, Hashimoto E, Ukai W, Saito T, Yamada M. Rhotekin modulates differentiation of cultured neural stem cells to neurons. J Neurosci Res 2012; 90:1359-66. [DOI: 10.1002/jnr.23029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Revised: 12/19/2011] [Accepted: 12/19/2011] [Indexed: 11/10/2022]
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Manuvakhova MS, Johnson GG, White MC, Ananthan S, Sosa M, Maddox C, McKellip S, Rasmussen L, Wennerberg K, Hobrath JV, White EL, Maddry JA, Grimaldi M. Identification of novel small molecule activators of nuclear factor-κB with neuroprotective action via high-throughput screening. J Neurosci Res 2011; 89:58-72. [PMID: 21046675 DOI: 10.1002/jnr.22526] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Neuronal noncytokine-dependent p50/p65 nuclear factor-κB (the primary NF-κB complex in the brain) activation has been shown to exert neuroprotective actions. Thus neuronal activation of NF-κB could represent a viable neuroprotective target. We have developed a cell-based assay able to detect NF-κB expression enhancement, and through its use we have identified small molecules able to up-regulate NF-κB expression and hence trigger its activation in neurons. We have successfully screened approximately 300,000 compounds and identified 1,647 active compounds. Cluster analysis of the structures within the hit population yielded 14 enriched chemical scaffolds. One high-potency and chemically attractive representative of each of these 14 scaffolds and four singleton structures were selected for follow-up. The experiments described here highlighted that seven compounds caused noncanonical long-lasting NF-κB activation in primary astrocytes. Molecular NF-κB docking experiments indicate that compounds could be modulating NF-κB-induced NF-κB expression via enhancement of NF-κB binding to its own promoter. Prototype compounds increased p65 expression in neurons and caused its nuclear translocation without affecting the inhibitor of NF-κB (I-κB). One of the prototypical compounds caused a large reduction of glutamate-induced neuronal death. In conclusion, we have provided evidence that we can use small molecules to activate p65 NF-κB expression in neurons in a cytokine receptor-independent manner, which results in both long-lasting p65 NF-κB translocation/activation and decreased glutamate neurotoxicity.
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Affiliation(s)
- Marina S Manuvakhova
- Laboratory of Neuropharmacology, Department of Biochemistry and Molecular Biology, Drug Discovery Division, Southern Research Institute, Birmingham, Alabama 35205, USA
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Lai RH, Hsiao YW, Wang MJ, Lin HY, Wu CW, Chi CW, Li AFY, Jou YS, Chen JY. SOCS6, down-regulated in gastric cancer, inhibits cell proliferation and colony formation. Cancer Lett 2010; 288:75-85. [DOI: 10.1016/j.canlet.2009.06.025] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2009] [Revised: 06/23/2009] [Accepted: 06/23/2009] [Indexed: 01/18/2023]
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Collier FM, Loving A, Baker AJ, McLeod J, Walder K, Kirkland MA. RTKN2 Induces NF-KappaB Dependent Resistance to Intrinsic Apoptosis in HEK Cells and Regulates BCL-2 Genes in Human CD4(+) Lymphocytes. J Cell Death 2009; 2:9-23. [PMID: 26124677 PMCID: PMC4474337 DOI: 10.4137/jcd.s2891] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The gene for Rhotekin 2 (RTKN2) was originally identified in a promyelocytic cell line resistant to oxysterol-induced apoptosis. It is differentially expressed in freshly isolated CD4+ T-cells compared with other hematopoietic cells and is down-regulated following activation of the T-cell receptor. However, very little is known about the function of RTKN2 other than its homology to Rho-GTPase effector, rhotekin, and the possibility that they may have similar roles. Here we show that stable expression of RTKN2 in HEK cells enhanced survival in response to intrinsic apoptotic agents; 25-hydroxy cholesterol and camptothecin, but not the extrinsic agent, TNFα. Inhibitors of NF-KappaB, but not MAPK, reversed the resistance and mitochondrial pro-apoptotic genes, Bax and Bim, were down regulated. In these cells, there was no evidence of RTKN2 binding to the GTPases, RhoA or Rac2. Consistent with the role of RTKN2 in HEK over-expressing cells, suppression of RTKN2 in primary human CD4+ T-cells reduced viability and increased sensitivity to 25-OHC. The expression of the pro-apoptotic genes, Bax and Bim were increased while BCL-2 was decreased. In both cell models RTKN2 played a role in the process of intrinsic apoptosis and this was dependent on either NF-KappaB signaling or expression of downstream BCL-2 genes. As RTKN2 is a highly expressed in CD4+ T-cells it may play a role as a key signaling switch for regulation of genes involved in T-cell survival.
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Affiliation(s)
- Fiona M Collier
- Barwon Biomedical Research, Geelong Hospital, Barwon Health, Ryrie St, Geelong, Victoria, 3227, Australia. ; Metabolic Research Unit, School of Medicine and Institute for Technology Research and Innovation, Deakin University, Waurn Ponds, Victoria, 3217, Australia
| | - Andrea Loving
- Barwon Biomedical Research, Geelong Hospital, Barwon Health, Ryrie St, Geelong, Victoria, 3227, Australia
| | - Adele J Baker
- Department of Malignant Haematology and Stem Cell Transplantation, The Alfred Hospital, Melbourne, Victoria, 3181, Australia
| | - Janet McLeod
- School of Medicine, Deakin University, Waurn Ponds, Victoria, 3217, Australia
| | - Ken Walder
- Metabolic Research Unit, School of Medicine and Institute for Technology Research and Innovation, Deakin University, Waurn Ponds, Victoria, 3217, Australia
| | - Mark A Kirkland
- Barwon Biomedical Research, Geelong Hospital, Barwon Health, Ryrie St, Geelong, Victoria, 3227, Australia
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Chen Y, Wang Y, Yu H, Wang F, Xu W. The cross talk between protein kinase A- and RhoA-mediated signaling in cancer cells. Exp Biol Med (Maywood) 2005; 230:731-41. [PMID: 16246900 DOI: 10.1177/153537020523001006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The cross talk between cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA) and RhoA-mediated signal transductions and the effect of this cross talk on biologic features of human prostate and gastric cancer cells were investigated. In the human gastric cancer cell line, SGC-7901, lysophosphatidic acid (LPA) increased RhoA activity in a dose-dependent manner. The cellular permeable cAMP analog, 8-chlorophenylthio-cAMP (CPT-cAMP), inhibited the LPA-induced RhoA activation and caused phosphorylation of RhoA at serine(188). Immunofluorescence microscopy, Western blotting, and green fluorescent protein (GFP)-tagged RhoA location assay in live cells revealed that RhoA was distributed in both the cytoplasm and nucleus of SGC-7901 cells. Treatment with LPA and/or CPT-cAMP did not induce obvious translocation of RhoA in the cells. The LPA treatment caused formation of F-actin in SGC-7901 cells, and CPT-cAMP inhibited the formation. In a modified Boyden chamber assay, LPA stimulated the migration of SGC-7901 cells, and CPT-cAMP dose-dependently inhibited the stimulating effect of LPA. In soft agar assay, LPA stimulated early proliferation of SGC-7901 cells, and CPT-cAMP significantly inhibited the growth of LPA-stimulated cells. In the prostate cancer cell line, PC-3, LPA caused morphologic changes from polygonal to round, and transfection with plasmid DNA encoding constitutively active RhoA(63L) caused a similar change. Treatment with CPT-cAMP inhibited the changes in both cases. However, in PC-3 cells transfected with a plasmid encoding mutant RhoA188A, LPA induced rounding, but CPT-cAMP could not prevent the change. Results of this experiment indicated that cAMP/PKA inhibited RhoA activation, and serine188 phosphorylation on RhoA was necessary for PKA to exert its inhibitory effect on RhoA activation. The cross talk between cAMP/PKA and RhoA-mediated signal transductions had significant affect on biologic features of gastric and prostate cancer cells, such as morphologic and cytoskeletal change, migration, and anchorage-independent growth. The results may be helpful in implementing novel therapeutic strategies for invasive and metastatic prostate and gastric cancers.
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Affiliation(s)
- Yongchang Chen
- School of Medicine, Jiangsu University, Zhenjiang, Jiangsu, Jiangsu 212001, China.
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Liu CA, Wang MJ, Chi CW, Wu CW, Chen JY. Rho/Rhotekin-mediated NF-kappaB activation confers resistance to apoptosis. Oncogene 2005; 23:8731-42. [PMID: 15480428 DOI: 10.1038/sj.onc.1208106] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Rhotekin (RTKN), the gene coding for the Rho effector, RTKN, was shown to be overexpressed in human gastric cancer (GC). In this study, we further showed that RTKN is expressed at a low level in normal cells and is overexpressed in many cancer-derived cell lines. The function of RTKN as an effector protein in Rho GTPase-mediated pathways regulating apoptosis was investigated. By transfection and expression of RTKN in cells that expressed endogenous RTKN at a low basal level, we showed that RTKN overexpression conferred cell resistance to apoptosis induced by serum deprivation or treatment with sodium butyrate, and the increased resistance correlated to the level of RTKN. Conversely, reducing RTKN expression by small interfering RNAs greatly sensitized cells to apoptosis. The RTKN-mediated antiapoptotic effect was blocked by the nuclear factor-kappaB (NF-kappaB) inhibitors, curcumin or parthenolide, but not by the phosphatidylinositol 3'-OH-kinase inhibitor, LY294002, or the MAP kinase inhibitor, PD98059. Reporter gene assays and electrophoretic mobility shift assay confirmed that RTKN overexpression led to constitutive activation of NF-kappaB through the phosphorylation of IkappaB by IKKbeta. By using the RTKN truncation mutants, we showed that RTKN mediated Rho activity eliciting signaling pathway to activate NF-kappaB, with a concomitant induction of expression of the NF-kappaB antiapoptotic genes, cIAP-2, BCl-xL, A1, and A20. Consistent with these data, RTKN-expressing cells showed increased chemoresistance to 5-fluorouracil and paclitaxol, and the resistance was greatly attenuated by NF-kappaB inhibitor. In conclusion, overactivated Rho/RTKN/NF-kappaB signaling pathway through overexpression of RTKN may play a key role in gastric tumorigenesis by conferring cells resistance to apoptosis, and this signaling pathway may serve as an important target for novel therapeutic approaches to the treatment of human GC.
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Affiliation(s)
- Ching-Ann Liu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taiwan, ROC
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Biomedical vignette. J Biomed Sci 2004. [DOI: 10.1007/bf02256118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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