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Feng M, Wang J, Li K, Nakamura F. UBE2A/B is the trans-acting factor mediating mechanotransduction and contact inhibition. Biochem J 2023; 480:1659-1674. [PMID: 37818922 DOI: 10.1042/bcj20230208] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 10/05/2023] [Accepted: 10/11/2023] [Indexed: 10/13/2023]
Abstract
Mechanotransduction and contact inhibition (CI) control gene expression to regulate proliferation, differentiation, and even tumorigenesis of cells. However, their downstream trans-acting factors (TAFs) are not well known due to a lack of a high-throughput method to quantitatively detect them. Here, we developed a method to identify TAFs on the cis-acting sequences that reside in open chromatin or DNaseI-hypersensitive sites (DHSs) and to detect nucleocytoplasmic shuttling TAFs using computational and experimental screening. The DHS-proteomics revealed over 1000 potential mechanosensing TAFs and UBE2A/B (Ubiquitin-conjugating enzyme E2 A) was experimentally identified as a force- and CI-dependent nucleocytoplasmic shuttling TAF. We found that translocation of YAP/TAZ and UBE2A/B are distinctively regulated by inhibition of myosin contraction, actin-polymerization, and CI depending on cell types. Next-generation sequence analysis revealed many downstream genes including YAP are transcriptionally regulated by ubiquitination of histone by UBE2A/B. Our results suggested a YAP-independent mechanotransduction and CI pathway mediated by UBE2A/B.
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Affiliation(s)
- Mingwei Feng
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
| | - Jiale Wang
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
| | - Kangjing Li
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
| | - Fumihiko Nakamura
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
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Deng Y, Li Y, Wu T, Chen X, Li X, Cai K, Wu X. RAD6 Positively Affects Tumorigenesis of Esophageal Squamous Cell Carcinoma by Regulating Histone Ubiquitination of CCNB1. Biol Proced Online 2022; 24:4. [PMID: 35321657 PMCID: PMC8943946 DOI: 10.1186/s12575-022-00165-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 02/21/2022] [Indexed: 11/23/2022] Open
Abstract
Objective Esophageal carcinoma (ESCA) is deadly cancer worldwide with unknown etiology. This study aimed to investigate the impact and mechanism of RAD6 on the development of Esophageal squamous cell carcinoma (ESCC). Expressions of RAD6A and RAD6B in ESCA were investigated from TCGA dataset and their expressions in tissue sample of ESCA patients and cells were determined. Functional experiments were conducted to explore the impact of RAD6A and RAD6B on malignant characteristics of several kinds of ESCC cells. Animal experiment was established and injected with RAD6A and RAD6B shRNA to evaluate the effect on tumor growth. RAD6A and RAD6B were up-regulated in ESCC cells and tissues. Overexpressed RAD6A and RAD6B similarly increased ESCC cell proliferation, invasion and migration and silencing of RAD6 exerted opposite effects. Knockdown of RAD6A suppressed tumor growth and decreased the level of H2B, as data demonstrated positive correlation between RAD6A and CCNB1 in ESCC tissues. Collectively, this study elucidates that RAD6 is up-regulated in ESCC and promotes the progression of ESCC through up-regulation of CCNB1 to enhance H2B ubiquitination. These evidence provide a novel insight into the pathogenesis of ESCC and might contribute to the development of targeted therapy.
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Affiliation(s)
- Yu Deng
- Department of Thoracic Surgery, Nanfang Hospital of Southern Medical University, Guangzhou, China
| | - Yujiang Li
- Department of Thoracic Surgery, Nanfang Hospital of Southern Medical University, Guangzhou, China.,Department of Thoracic and Cardiovascular Surgery, Affiliated Dongguan People's Hospital, Southern Medical University, Dongguan, China
| | - Tiantong Wu
- Department of General Surgery, Nanfang Hospital of Southern Medical University, Guangzhou, China
| | - Xuyuan Chen
- Department of Thoracic Surgery, Nanfang Hospital of Southern Medical University, Guangzhou, China
| | - Xiang Li
- Department of Emergency Medicine, Nanfang Hospital of Southern Medical University, Guangzhou, China
| | - Kaican Cai
- Department of Thoracic Surgery, Nanfang Hospital of Southern Medical University, Guangzhou, China.
| | - Xu Wu
- Department of Thoracic Surgery, Nanfang Hospital of Southern Medical University, Guangzhou, China.
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3
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Ubiquitin-Conjugating Enzymes in Cancer. Cells 2021; 10:cells10061383. [PMID: 34199813 PMCID: PMC8227520 DOI: 10.3390/cells10061383] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/28/2021] [Accepted: 05/30/2021] [Indexed: 12/22/2022] Open
Abstract
The ubiquitin-mediated degradation system is responsible for controlling various tumor-promoting processes, including DNA repair, cell cycle arrest, cell proliferation, apoptosis, angiogenesis, migration and invasion, metastasis, and drug resistance. The conjugation of ubiquitin to a target protein is mediated sequentially by the E1 (activating)‒E2 (conjugating)‒E3 (ligating) enzyme cascade. Thus, E2 enzymes act as the central players in the ubiquitination system, modulating various pathophysiological processes in the tumor microenvironment. In this review, we summarize the types and functions of E2s in various types of cancer and discuss the possibility of E2s as targets of anticancer therapeutic strategies.
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Gajan A, Martin CE, Kim S, Joshi M, Michelhaugh SK, Sloma I, Mittal S, Firestine S, Shekhar MPV. Alternative Splicing of RAD6B and Not RAD6A is Selectively Increased in Melanoma: Identification and Functional Characterization. Cells 2019; 8:E1375. [PMID: 31683936 PMCID: PMC6912459 DOI: 10.3390/cells8111375] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/28/2019] [Accepted: 10/31/2019] [Indexed: 12/31/2022] Open
Abstract
Rad6B, a principal component of the translesion synthesis pathway, and activator of canonical Wnt signaling, plays an essential role in cutaneous melanoma development and progression. As Rad6 is encoded by two genes, namely, UBE2A (RAD6A) and UBE2B (RAD6B), in humans, we compared their expressions in melanomas and normal melanocytes. While both genes are weakly expressed in normal melanocytes, Rad6B is more robustly expressed in melanoma lines and patient-derived metastatic melanomas than RAD6A. The characterization of RAD6B transcripts revealed coexpression of various splice variants representing truncated or modified functional versions of wild-type RAD6B in melanomas, but not in normal melanocytes. Notably, two RAD6B isoforms with intact catalytic domains, RAD6BΔexon4 and RAD6Bintron5ins, were identified. We confirmed that RAD6BΔexon4 and RAD6Bintron5ins variants are expressed as 14 and 15 kDa proteins, respectively, with functional in vivo ubiquitin conjugating activity. Whole exome sequence analysis of 30 patient-derived melanomas showed RAD6B variants coexpressed with wild-type RAD6B in all samples analyzed, and RAD6Bintron5ins variants were found in half the cases. These variants constitute the majority of the RAD6B transcriptome in contrast to RAD6A, which was predominantly wild-type. The expression of functional RAD6B variants only in melanomas reveals RAD6B's molecular heterogeneity and its association with melanoma pathogenesis.
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Affiliation(s)
- Ambikai Gajan
- Karmanos Cancer Institute, Detroit, MI 48201, USA.
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Carly E Martin
- Karmanos Cancer Institute, Detroit, MI 48201, USA.
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Seongho Kim
- Karmanos Cancer Institute, Detroit, MI 48201, USA.
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Milap Joshi
- Karmanos Cancer Institute, Detroit, MI 48201, USA.
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Sharon K Michelhaugh
- Karmanos Cancer Institute, Detroit, MI 48201, USA.
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Ido Sloma
- Champions Oncology, Rockville, MD 20850, USA.
| | - Sandeep Mittal
- Karmanos Cancer Institute, Detroit, MI 48201, USA.
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
| | - Steven Firestine
- Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA.
| | - Malathy P V Shekhar
- Karmanos Cancer Institute, Detroit, MI 48201, USA.
- Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
- Department of Pathology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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Larivé E, Nicolas M, Kaya G, Riggi N, Moulin AP. β-Catenin Expression and Activation in Conjunctival Melanoma. Dermatopathology (Basel) 2019; 6:50-62. [PMID: 31700844 PMCID: PMC6827456 DOI: 10.1159/000500682] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 04/10/2019] [Indexed: 12/12/2022] Open
Abstract
Purpose To assess the role of the canonical Wnt pathway via activation of β-catenin in tumor progression of conjunctival melanoma. Methods β-Catenin localization was assessed by immunohistochemistry in 43 conjunctival nevi, 48 primary acquired melanoses (PAM; conjunctival melanocytic intraepithelial neoplasia), and 44 conjunctival melanomas. Activation of the canonical or the noncanonical Wnt pathway was tested in vitro in 4 conjunctival melanoma cell lines with stimulation of either Wnt5a or Wnt3a. Wound healing assays were performed with Wnt5a. Results Nuclear β-catenin expression was found in 16% of the nevi, in 15% of the melanomas, and in 4% of the PAM. Membranous β-catenin expression was identified in all the nevi and PAM and in 97.7% of the melanomas. In vitro, Wnt5a stimulation in the 4 conjunctival melanomas and in 1 skin melanoma cell line did not induce nuclear translocation of β-catenin, nor did it increase cell motility in the wound healing assays. Wnt3a stimulation did not induce nuclear localization of β-catenin in any of the cell lines tested. Conclusions In conjunctival melanoma, nuclear localization and activation of β-catenin appear to be limited, suggesting that inhibition of ARF6, responsible for β-catenin activation, in subsets of skin melanoma may not represent a treatment option for this tumor. In vitro, Wnt3a or Wnt5a did not induce nuclear β-catenin localization.
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Affiliation(s)
| | - Michael Nicolas
- Jules-Gonin Eye Hospital, Lausanne University, FAA, Lausanne, Switzerland
| | - Gürkan Kaya
- Dermatopathology Unit, Department of Dermatology, University Hospital of Geneva, Geneva, Switzerland
| | - Nicolo Riggi
- Experimental Pathology, Lausanne University Pathology Institute, Lausanne, Switzerland
| | - Alexandre P Moulin
- Jules-Gonin Eye Hospital, Lausanne University, FAA, Lausanne, Switzerland
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Somasagara RR, Spencer SM, Tripathi K, Clark DW, Mani C, da Silva LM, Scalici J, Kothayer H, Westwell AD, Rocconi RP, Palle K. RAD6 promotes DNA repair and stem cell signaling in ovarian cancer and is a promising therapeutic target to prevent and treat acquired chemoresistance. Oncogene 2017; 36:6680-6690. [PMID: 28806395 PMCID: PMC5709226 DOI: 10.1038/onc.2017.279] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 06/14/2017] [Accepted: 07/07/2017] [Indexed: 12/28/2022]
Abstract
Ovarian cancer (OC) is the most deadly gynecological cancer and unlike most other neoplasms, survival rates for OC have not significantly improved in recent decades. We show that RAD6, an ubiquitin-conjugating enzyme, is significantly overexpressed in ovarian tumors and its expression increases in response to carboplatin chemotherapy. RAD6 expression correlated strongly with acquired chemoresistance and malignant behavior of OC cells, expression of stem cell genes and poor prognosis of OC patients, suggesting an important role for RAD6 in ovarian tumor progression. Upregulated RAD6 enhances DNA damage tolerance and repair efficiency of OC cells and promotes their survival. Increased RAD6 levels cause histone 2B ubiquitination-mediated epigenetic changes that stimulate transcription of stem cell genes, including ALDH1A1 and SOX2, leading to a cancer stem cell phenotype, which is implicated in disease recurrence and metastasis. Downregulation of RAD6 or its inhibition using a small molecule inhibitor attenuated DNA repair signaling and expression of cancer stem cells markers and sensitized chemoresistant OC cells to carboplatin. Together, these results suggest that RAD6 could be a therapeutic target to prevent and treat acquired chemoresistance and disease recurrence in OC and enhance the efficacy of standard chemotherapy.
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Affiliation(s)
- Ranganatha R. Somasagara
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Sebastian M. Spencer
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Kaushlendra Tripathi
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - David W. Clark
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Chinnadurai Mani
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Luciana Madeira da Silva
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Jennifer Scalici
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Hend Kothayer
- Department of Medicinal Chemistry, Faculty of Pharmacy, Zagazig University, Egypt
| | - Andrew D. Westwell
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK
| | - Rodney P. Rocconi
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
| | - Komaraiah Palle
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, Alabama 36604, USA
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Kothayer H, Spencer SM, Tripathi K, Westwell AD, Palle K. Synthesis and in vitro anticancer evaluation of some 4,6-diamino-1,3,5-triazine-2-carbohydrazides as Rad6 ubiquitin conjugating enzyme inhibitors. Bioorg Med Chem Lett 2016; 26:2030-4. [PMID: 26965855 DOI: 10.1016/j.bmcl.2016.02.085] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/24/2016] [Accepted: 02/27/2016] [Indexed: 01/30/2023]
Abstract
Series of 4-amino-6-(arylamino)-1,3,5-triazine-2-carbohydrazides (3a-e) and N'-phenyl-4,6-bis(arylamino)-1,3,5-triazine-2-carbohydrazides (6a-e), for ease of readership, we will abbreviate our compound names as 'new triazines', have been synthesized, based on the previously reported Rad6B-inhibitory diamino-triazinylmethyl benzoate anticancer agents TZ9 and 4-amino-N'-phenyl-6-(arylamino)-1,3,5-triazine-2-carbohydrazides. Synthesis of the target compounds was readily accomplished in two steps from either bis-aryl/aryl biguanides via reaction of phenylhydrazine or hydrazinehydrate with key 4-amino-6-bis(arylamino)/(arylamino)-1,3,5-triazine-2-carboxylate intermediates. These new triazine derivatives were evaluated for their abilities to inhibit Rad6B ubiquitin conjugation and in vitro anticancer activity against several human cancer cell lines: ovarian (OV90 and A2780), lung (H1299 and A549), breast (MCF-7 and MDA-MB231) and colon (HT29) cancer cells by MTS assays. All the 10 new triazines exhibited superior Rad6B inhibitory activities in comparison to selective Rad6 inhibitor TZ9 that was reported previously. Similarly, new triazines also showed better IC50 values in survival assays of various tumor cell lines. Particularly, new triazines 6a-c, exhibited lower IC50 (3.3-22 μM) values compared to TZ9.
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Affiliation(s)
- Hend Kothayer
- Department of Medicinal Chemistry, Faculty of Pharmacy, Zagazig University, Egypt.
| | - Sebastian M Spencer
- Department of Oncologic Sciences, USA Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Kaushlendra Tripathi
- Department of Oncologic Sciences, USA Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Andrew D Westwell
- School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff CF10 3NB, Wales, UK
| | - Komaraiah Palle
- Department of Oncologic Sciences, USA Mitchell Cancer Institute, 1660 Springhill Avenue, Mobile, AL 36604, USA
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Somasagara RR, Tripathi K, Spencer SM, Clark DW, Barnett R, Bachaboina L, Scalici J, Rocconi RP, Piazza GA, Palle K. Rad6 upregulation promotes stem cell-like characteristics and platinum resistance in ovarian cancer. Biochem Biophys Res Commun 2015; 469:449-55. [PMID: 26679603 DOI: 10.1016/j.bbrc.2015.11.134] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 11/25/2015] [Accepted: 11/30/2015] [Indexed: 10/22/2022]
Abstract
Ovarian cancer is the fifth most deadly cancer in women in the United States and despite advances in surgical and chemotherapeutic treatments survival rates have not significantly improved in decades. The poor prognosis for ovarian cancer patients is largely due to the extremely high (80%) recurrence rate of ovarian cancer and because the recurrent tumors are often resistant to the widely utilized platinum-based chemotherapeutic drugs. In this study, expression of Rad6, an E2 ubiquitin-conjugating enzyme, was found to strongly correlate with ovarian cancer progression. Furthermore, in ovarian cancer cells Rad6 was found to stabilize β-catenin promoting stem cell-related characteristics, including expression of stem cell markers and anchorage-independent growth. Cancer stem cells can promote chemoresistance, tumor recurrence and metastasis, all of which are limiting factors in treating ovarian cancer. Thus it is significant that Rad6 overexpression led to increased resistance to the chemotherapeutic drug carboplatin and correlated with tumor cell invasion. These findings show the importance of Rad6 in ovarian cancer and emphasize the need for further studies of Rad6 as a potential target for the treatment of ovarian cancer.
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Affiliation(s)
- Ranganatha R Somasagara
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Kaushlendra Tripathi
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Sebastian M Spencer
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - David W Clark
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Reagan Barnett
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Lavanya Bachaboina
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Jennifer Scalici
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Rodney P Rocconi
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Gary A Piazza
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA
| | - Komaraiah Palle
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA.
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Rosner K, Adsule S, Haynes B, Kirou E, Kato I, Mehregan DR, Shekhar MPV. Rad6 is a Potential Early Marker of Melanoma Development. Transl Oncol 2014; 7:S1936-5233(14)00044-8. [PMID: 24831578 PMCID: PMC4145396 DOI: 10.1016/j.tranon.2014.04.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/24/2014] [Accepted: 03/24/2014] [Indexed: 11/17/2022] Open
Abstract
Melanoma is the leading cause of death from skin cancer in industrialized countries. Several melanoma-related biomarkers and signaling pathways have been identified; however, their relevance to melanoma development/progression or to clinical outcome remains to be established. Aberrant activation of Wnt/β-catenin pathway is implicated in various cancers including melanoma. We have previously demonstrated Rad6, an ubiquitin-conjugating enzyme, as an important mediator of β-catenin stability in breast cancer cells. Similar to breast cancer, β-catenin-activating mutations are rare in melanomas, and since β-catenin signaling is implicated in melanoma, we examined the relationship between β-catenin levels/activity and expression of β-catenin transcriptional targets Rad6 and microphthalmia-associated transcription factor-M (Mitf-M) in melanoma cell models, and expression of Rad6, β-catenin, and Melan-A in nevi and cutaneous melanoma tissue specimens. Our data show that Rad6 is only weakly expressed in normal human melanocytes but is overexpressed in melanoma lines. Unlike Mitf-M, Rad6 overexpression in melanoma lines is positively associated with high molecular weight β-catenin protein levels and β-catenin transcriptional activity. Double-immunofluorescence staining of Rad6 and Melan-A in melanoma tissue microarray showed that histological diagnosis of melanoma is significantly associated with Rad6/Melan-A dual positivity in the melanoma group compared to the nevi group (P=.0029). In contrast to strong β-catenin expression in normal and tumor areas of superficial spreading malignant melanoma (SSMM), Rad6 expression is undetectable in normal areas and Rad6 expression increases coincide with increased Melan-A in the transformed regions of SSMM. These data suggest a role for Rad6 in melanoma pathogenesis and that Rad6 expression status may serve as an early marker for melanoma development.
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Affiliation(s)
- Karli Rosner
- Department of Dermatology, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201; Center for Molecular Medicine and Genetics, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201; Karmanos Cancer Institute, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201.
| | - Shreelekha Adsule
- Department of Oncology, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201
| | - Brittany Haynes
- Karmanos Cancer Institute, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201; Department of Oncology, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201
| | - Evangelia Kirou
- Department of Dermatology, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201
| | - Ikuko Kato
- Karmanos Cancer Institute, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201; Department of Oncology, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201
| | - Darius R Mehregan
- Department of Dermatology, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201
| | - Malathy P V Shekhar
- Karmanos Cancer Institute, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201; Department of Oncology, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201; Department of Pathology, Wayne State University, 110, East Warren Avenue, Detroit, MI 48201.
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