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Xu H, Wang X, Zhu F, Guo S, Chao Z, Cao C, Lu Z, Zhu H, Wang M, Zhu F, Yang J, Zeng R, Yao Y. Comprehensive Pan-Cancer Analysis of Connexin 43 as a Potential Biomarker and Therapeutic Target in Human Kidney Renal Clear Cell Carcinoma (KIRC). MEDICINA (KAUNAS, LITHUANIA) 2024; 60:780. [PMID: 38792963 PMCID: PMC11123162 DOI: 10.3390/medicina60050780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 04/22/2024] [Accepted: 05/06/2024] [Indexed: 05/26/2024]
Abstract
Background and Objectives: Connexin 43 (Cx43) is involved in the transfer of small signaling molecules between neighboring cells, thereby exerting a major influence on the initiation and progression of tumorigenesis. However, there is a lack of systematic research on Cx43 expression and its predictive role in clinical diagnosis and prognosis in pan-cancer. Materials and Methods: Several biological databases were used to evaluate the expression levels of GJA1 (encoding Cx43) and its diagnostic and prognostic significance in pan-cancer. We targeted kidney renal clear cell carcinoma (KIRC) and investigated the relationship between GJA1 expression and different clinical features of KIRC patients. Then, we performed cell-based experiments to partially confirm our results and predicted several proteins that were functionally related to Cx43. Results: The expression of GJA1 has a high level of accuracy in predicting KIRC. High GJA1 expression was remarkably correlated with a favorable prognosis, and this expression was reduced in groups with poor clinical features in KIRC. Cell experiments confirmed the inhibitory effects of increased GJA1 expression on the migratory capacity of human renal cancer (RCC) cell lines, and protein-protein interaction (PPI) analysis predicted that CDH1 and CTNNB1 were closely related to Cx43. Conclusions: GJA1 could be a promising independent favorable prognostic factor for KIRC, and upregulation of GJA1 expression could inhibit the migratory capacity of renal cancer cells.
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Affiliation(s)
- Huzi Xu
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
| | - Xiuru Wang
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
| | - Fan Zhu
- Wuhan Central Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China;
| | - Shuiming Guo
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
| | - Zheng Chao
- Division of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China;
| | - Chujin Cao
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
| | - Zhihui Lu
- Division of Nursing, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China;
| | - Han Zhu
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
| | - Meng Wang
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
| | - Fengming Zhu
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
| | - Juan Yang
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
| | - Rui Zeng
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
| | - Ying Yao
- Division of Nephrology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China; (H.X.); (X.W.); (S.G.); (C.C.); (H.Z.); (M.W.); (F.Z.); (J.Y.)
- Division of Nutrition, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan 430030, China
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Scatolini M, Patel A, Grosso E, Mello-Grand M, Ostano P, Coppo R, Vitiello M, Venesio T, Zaccagna A, Pisacane A, Sarotto I, Taverna D, Poliseno L, Bergamaschi D, Chiorino G. GJB5 association with BRAF mutation and survival in cutaneous malignant melanoma. Br J Dermatol 2021; 186:117-128. [PMID: 34240406 DOI: 10.1111/bjd.20629] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/03/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND Gap junctional intercellular communication is crucial for epidermal cellular homeostasis. Inability to establish melanocyte-keratinocytes contacts and loss of intercellular junction's integrity may contribute to melanoma development. Connexins, laminins and desmocollins have been implicated in the control of melanoma growth, where their reduced expression has been reported in metastatic lesions. OBJECTIVES The aim of this study was to investigate Connexin 31.1 (GJB5) expression and identify any association with BRAF mutational status, melanoma patient prognosis and MAPK inhibitors (MAPKi) treatment. MATERIAL AND METHODS GJB5 expression was measured at RNA and protein level in melanoma clinical samples and established cell lines treated or not with BRAF and MEK inhibitors, as well as in cell lines which developed MAPK inhibitors resistance. Findings were further validated and confirmed by analysis of independent datasets. RESULTS Our analysis reveals significant downregulation of GJB5 expression in metastatic melanoma lesions compared to primary ones and in BRAF mutated versus BRAF wild-type melanomas. Likewise, GJB5 expression is significantly lower in BRAFV600E compared with BRAFWT cell lines and increases upon MAPKi treatment. MAPKi-resistant melanoma cells display a similar expression pattern compared to BRAFWT cells, with increased GJB5 expression associated with morphological changes. Enhancement of BRAFV600E expression in BRAFWT melanoma cells significantly upregulates miR-335-5p expression with consequent downregulation of GJB5, one of its targets. Furthermore, overexpression of miR-335-5p in two BRAFWT cell lines confirms specific GJB5 protein downregulation. RT-qPCR analysis also revealed upregulation of miR-335 in BRAFV600E melanoma cells, which is significantly downregulated in cells resistant to MEK inhibitors. Our data were further validated using the TCGA-SKCM dataset, where BRAF mutations associate with increased miR-335 expression and inversely correlate with GJB5 expression. In clinical samples, GJB5 underexpression is also associated with patient overall worse survival, especially at early stages. CONCLUSION We identified a significant association between metastases / BRAF mutation and low GJB5 expression in melanoma. Our results identify a novel mechanism of Gap-junctional protein regulation, suggesting a prognostic role for GJB5 in cutaneous melanoma.
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Affiliation(s)
- M Scatolini
- Molecular Oncology Laboratory, Fondazione Edo ed Elvo Tempia, 13875, Ponderano, BI, Italy
| | - A Patel
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London SMD, QMUL, London, E1 2AT, UK
| | - E Grosso
- Molecular Oncology Laboratory, Fondazione Edo ed Elvo Tempia, 13875, Ponderano, BI, Italy
| | - M Mello-Grand
- Cancer Genomics Laboratory, Fondazione Edo ed Elvo Tempia, 13900, Biella, Italy
| | - P Ostano
- Cancer Genomics Laboratory, Fondazione Edo ed Elvo Tempia, 13900, Biella, Italy
| | - R Coppo
- Molecular Biotechnology Centre, 10126, Torino, Italy.,Department of Clinical Bio-Resource Research and Development, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - M Vitiello
- Oncogenomics Unit, Core Research Laboratory, Istituto Toscano Tumori, Institute of Clinical Physiology, CNR, 56124, Pisa, Italy
| | - T Venesio
- Pathology and Dermosurgery Units, Candiolo Cancer Institute (FPO-IRCCS), 10060, Candiolo, Turin, Italy
| | - A Zaccagna
- Pathology and Dermosurgery Units, Candiolo Cancer Institute (FPO-IRCCS), 10060, Candiolo, Turin, Italy
| | - A Pisacane
- Pathology and Dermosurgery Units, Candiolo Cancer Institute (FPO-IRCCS), 10060, Candiolo, Turin, Italy
| | - I Sarotto
- Pathology and Dermosurgery Units, Candiolo Cancer Institute (FPO-IRCCS), 10060, Candiolo, Turin, Italy
| | - D Taverna
- Molecular Biotechnology Centre, 10126, Torino, Italy
| | - L Poliseno
- Oncogenomics Unit, Core Research Laboratory, Istituto Toscano Tumori, Institute of Clinical Physiology, CNR, 56124, Pisa, Italy
| | - D Bergamaschi
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and The London SMD, QMUL, London, E1 2AT, UK
| | - G Chiorino
- Cancer Genomics Laboratory, Fondazione Edo ed Elvo Tempia, 13900, Biella, Italy
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Connexins and Gap Junctions in Cancer of the Urinary Tract. Cancers (Basel) 2019; 11:cancers11050704. [PMID: 31121877 PMCID: PMC6563010 DOI: 10.3390/cancers11050704] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/13/2019] [Accepted: 05/20/2019] [Indexed: 12/11/2022] Open
Abstract
This review focuses on connexins and nexus or gap junctions in the genesis, progression, and therapy of carcinomas of the human urinary tract. Some decades ago, the idea was born that gap junctional intercellular communication might prevent both the onset and the progression of cancer. Later evidence indicated that, on the contrary, synthesis and the presence of connexins as a prerequisite for gap junctional intercellular communication might promote the occurrence of cancer and metastases. The research history of urinary bladder cancer is a good example of the development of scientific perception. So far, the role of gap junctional intercellular communication in carcinogenesis and cancer progression, as well as in therapeutical approaches, remains unclear.
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Schultze E, Collares T, Lucas CG, Seixas FK. Synergistic and additive effects of ATRA in combination with different anti-tumor compounds. Chem Biol Interact 2018; 285:69-75. [DOI: 10.1016/j.cbi.2018.02.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 01/26/2018] [Accepted: 02/15/2018] [Indexed: 12/12/2022]
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Connexin 43 communication channels in follicular dendritic cell development and in follicular lymphomas. J Immunol Res 2015; 2015:528098. [PMID: 25815348 PMCID: PMC4359865 DOI: 10.1155/2015/528098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 02/09/2015] [Accepted: 02/11/2015] [Indexed: 02/05/2023] Open
Abstract
Follicular dendritic cells (FDC) show homo- and heterocellular metabolic coupling through connexin 43 (Cx43) gap junctions and support B cell selection and maturation in germinal centers. In follicular lymphomas B cells escape apoptosis while FDC develop abnormally. Here we tested Cx43 channels in reactive FDC development and follicular lymphomas. In culture, the treatment of FDC-B cell clusters (resembling to “ex vivo” germinal centers) with Gap27 peptide, mimicking the 2nd extracellular loop of Cx43 protein, significantly impaired FDC-B cell cluster formation and cell survival. In untreated cultures of intact clusters, cell proliferation showed a moderate reduction. In tissues, Cx43 protein levels run parallel with the density of FDC both in reactive germinal centers and in malformed follicles of follicular lymphomas and showed strong upregulation in newly generated and/or degrading bi-/multinuclear FDC of rudimentary processes. However, the inverse correlation between Cx43 expression and B cell proliferation seen in reactive germinal centers was not detected in follicular lymphomas. Furthermore, Cx43 levels were not associated with either lymphoma grade or bone marrow involvement. Our results suggest that Cx43 channels are critical in FDC and “ex vivo” germinal center development and in the persistence of FDC in follicular lymphomas but do not affect tumor progression.
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Yang Y, Qin SK, Wu Q, Wang ZS, Zheng RS, Tong XH, Liu H, Tao L, He XD. Connexin-dependent gap junction enhancement is involved in the synergistic effect of sorafenib and all-trans retinoic acid on HCC growth inhibition. Oncol Rep 2013; 31:540-50. [PMID: 24317203 PMCID: PMC3896525 DOI: 10.3892/or.2013.2894] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 11/19/2013] [Indexed: 12/11/2022] Open
Abstract
Increasing gap junction activity in tumor cells provides a target by which to enhance antineoplastic therapies. Previously, several naturally occurring agents, including all-trans retinoic acid (ATRA) have been demonstrated to increase gap junctional intercellular communication (GJIC) in a number of types of cancer cells. In the present study, we investigated in vitro whether ATRA modulates the response of human hepatocellular carcinoma (HCC) cells to sorafenib, the only proven oral drug for advanced HCC, and the underlying mechanisms. HepG2 and SMMC-7721 cells were treated with sorafenib and/or ATRA, and cell proliferation and apoptosis were analyzed; the role of GJIC was also explored. We found that ATRA, at non-toxic concentrations, enhanced sorafenib-induced growth inhibition in both HCC cell lines, and this effect was abolished by two GJIC inhibitors, 18-α-GA and oleamide. Whereas lower concentrations of sorafenib (5 µM) or ATRA (0.1 or 10 µM) alone modestly induced GJIC activity, the combination of sorafenib plus ATRA resulted in a strong enhancement of GJIC. However, the action paradigm differed in the HepG2 and SMMC-7721 cells, with the dominant effect of GJIC dependent on the cell-specific connexin increase in protein amounts and relocalization. RT-PCR assay further revealed a transcriptional modification of the key structural connexin in the two cell lines. Thus, a connexin-dependent gap junction enhancement may play a central role in ATRA plus sorafenib synergy in inhibiting HCC cell growth. Since both agents are available for human use, the combination treatment represents a future profitable strategy for the treatment of advanced HCC.
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Affiliation(s)
- Yan Yang
- Department of Medical Oncology, The First Affiliated Hospital of Bengbu Medical College, Bengbu 233004, P.R. China
| | - Shu-Kui Qin
- Department of Medical Oncology, PLA Cancer Center, Nanjing Bayi Hospital, Nanjing 210002, P.R. China
| | - Qiong Wu
- Department of Medical Oncology, The First Affiliated Hospital of Bengbu Medical College, Bengbu 233004, P.R. China
| | - Zi-Shu Wang
- Department of Medical Oncology, The First Affiliated Hospital of Bengbu Medical College, Bengbu 233004, P.R. China
| | - Rong-Sheng Zheng
- Department of Medical Oncology, The First Affiliated Hospital of Bengbu Medical College, Bengbu 233004, P.R. China
| | - Xu-Hui Tong
- Department of Pharmacy, Bengbu Medical College, Bengbu 233000, P.R. China
| | - Hao Liu
- Department of Pharmacy, Bengbu Medical College, Bengbu 233000, P.R. China
| | - Liang Tao
- Department of Pharmacology, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510080, P.R. China
| | - Xian-Di He
- Department of Intensive Care, The First Affiliated Hospital of Bengbu Medical College, Bengbu 233004, P.R. China
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Wang J, Dai Y, Huang Y, Chen X, Wang H, Hong Y, Xia J, Cheng B. All-trans retinoic acid restores gap junctional intercellular communication between oral cancer cells with upregulation of Cx32 and Cx43 expressions in vitro. Med Oral Patol Oral Cir Bucal 2013; 18:e569-77. [PMID: 23524428 PMCID: PMC3731083 DOI: 10.4317/medoral.18693] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 12/31/2012] [Indexed: 01/11/2023] Open
Abstract
OBJECTIVE All-trans retinoic acid (ATRA) has been demonstrated to inhibit tumor growth by restoration of gap junctional intercellular communication (GJIC) via upregulation of connexin (Cx) expression in some solid tumors. However, the relationship between ATRA and GJIC remains unclear in oral squamous cell carcinoma (OSCC). The aim of this study was to investigate the effect of ATRA on the GJIC function of OSCC. STUDY DESIGN We measured the effects of ATRA on the viability and cell cycle distribution of SCC9 and Tca8113 OSCC cells. The GJIC function was observed using the scrape-loading dye transfer technique, and the mRNA and protein levels of Cx32 and Cx43 were detected by qRT-PCR, Western blot, and immunofluorescence assays. RESULTS ATRA inhibited the growth of OSCC cells in a dose- and time-dependent manner (P <0.05) and caused cell cycle arrest. ATRA-treated cells showed a 2.69-fold and 2.06-fold enhancement of GJIC in SCC9 and Tca8113 cells, respectively (P <0.05). Moreover, ATRA induced upregulation of Cx32 and Cx43 at both the mRNA and protein levels in OSCC cells. CONCLUSION Our results indicated that restoration of GJIC via enhanced Cx32 and Cx43 expression might serve as a novel mechanism for the anti-tumor effect of ATRA in OSCC.
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Affiliation(s)
- Juan Wang
- Department of Oral Medicine, The Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou 510060, China
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Wang Y, Zhu Q, Luo C, Zhang A, Hei Z, Su G, Xia Z, Irwin MG. Dual Effects of Bilirubin on the Proliferation of Rat Renal NRK52E Cells and ITS Association with Gap Junctions. Dose Response 2012; 11:220-37. [PMID: 23930103 PMCID: PMC3682199 DOI: 10.2203/dose-response.12-003.hei] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
OBJECTIVE The effect of bilirubin on renal pathophysiology is controversial. This study aimed to observe the effects of bilirubin on the proliferation of normal rat renal tubular epithelial cell line (NRK52E) and its potential interplay with gap junction function. METHODS Cultured NRK52E cells, seeded respectively at high- or low- densities, were treated with varying concentrations of bilirubin for 24 hours. Cell injury was assessed by measuring cell viability and proliferation, and gap junction function was assessed by Parachute dye-coupling assay. Connexin 43 protein was assessed by Western blotting. RESULTS At doses from 17.1 to 513μmol/L, bilirubin dose-dependently enhanced cell viability and colony-formation rates when cells were seeded at either high- or low- densities (all p<0.05 vs. solvent group) accompanied with enhanced intercellular fluorescence transmission and increased Cx43 protein expression in high-density cells. However, the above effects of BR were gradually reversed when its concentration increased from 684 to 1026μmol/L. In high-density cells, gap junction inhibitor 12-O-tetradecanoylphorbol 13-acetate attenuated bilirubin-induced enhancement of colony-formation and fluorescence transmission. However, in the presence of high concentration bilirubin (1026μmol/L), activation of gap junction with retinoid acid decreased colony-formation rates. CONCLUSION Bilirubin can confer biphasic effects on renal NRK52E cell proliferation potentially by differentially affecting gap junction functions.
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Affiliation(s)
- Yanling Wang
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Qiongfang Zhu
- Department of Anesthesiology, the first affiliated hospital of Sun Yat-sen university. NO.58, Zhongshan Road II, Yuexiu district, Guangzhou, China
| | - Chenfang Luo
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Ailan Zhang
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Ziqing Hei
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Guangjie Su
- Department of anesthesiology, the third affiliated hospital of Sun Yat-sen university. NO.600 Tianhe Road, Tianhe district, Guangzhou, China, 510630
| | - Zhengyuan Xia
- Department of Anesthesiology, University of Hong Kong. Room 424, 4th Floor, Block K, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong, China
| | - Michael G. Irwin
- Department of Anesthesiology, University of Hong Kong. Room 424, 4th Floor, Block K, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong, China
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Long AC, Bomser JA, Grzybowski DM, Chandler HL. All-trans retinoic Acid regulates cx43 expression, gap junction communication and differentiation in primary lens epithelial cells. Curr Eye Res 2010; 35:670-9. [PMID: 20673043 DOI: 10.3109/02713681003770746] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To examine the effect of all-trans retinoic acid (ATRA) treatment on connexin 43 (Cx43) expression, gap junction intercellular communication (GJIC), and cellular differentiation in primary canine lens epithelial cells (LEC). METHODS AND MATERIALS Dose and time-dependent effects of ATRA on Cx43 protein, mRNA and GJIC, were assessed by immunoblotting, quantitative reverse transcription polymerase chain reaction (qRT-PCR), and scrape loading/dye transfer assays, respectively. Expression of beta crystallin was evaluated by immunoblotting. RESULTS Treatment with ATRA at non-cytotoxic concentrations significantly increased Cx43 protein, mRNA and GJIC in primary canine LEC. Treatment with ATRA for five and seven days increased levels of beta crystallin, a protein marker of LEC differentiation. Inhibition of GJIC via pre-treatment with a synthetic inhibitor, 18-alpha glycyrrethinic acid (AGA), reduced ATRA-induced increases in Cx43 and GJIC and partially blocked ATRA-induced beta crystallin protein. CONCLUSIONS Treatment with ATRA significantly increased Cx43 expression and GJIC in canine LEC, and these effects were associated with increased LEC differentiation. Results from this study suggest that functional gap junctions may play a role in the modulation of cellular differentiation in primary canine LEC.
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Affiliation(s)
- Amy C Long
- The Ohio State University, Interdisciplinary Ph.D Program in Nutrition, Department of Human Nutrition, Department of Ophthalmology, Biomedical Engineering Center, College of Optometry, Department of Veterinary Clinical Sciences, Columbus, Ohio, USA
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Hayashi K, Lee JB, Maitani Y, Toyooka N, Nemoto H, Hayashi T. The role of a HSV thymidine kinase stimulating substance, scopadulciol, in improving the efficacy of cancer gene therapy. J Gene Med 2006; 8:1056-67. [PMID: 16779868 DOI: 10.1002/jgm.931] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The most extensively investigated strategy of suicide gene therapy for treatment of cancer is the transfer of the herpes simplex virus thymidine kinase (HSV-TK) gene followed by administration of antiviral prodrugs such as acyclovir (ACV) and ganciclovir (GCV). The choice of the agent that can stimulate HSV-TK enzymatic activity is one of the determinants of the usefulness of this strategy. Previously, we found that a diterpenoid, scopadulciol (SDC), produced a significant increase in the active metabolite of ACV. This suggests that SDC may play a role in the HSV-TK/prodrug administration system. METHODS The anticancer effect of SDC was evaluated in HSV-TK-expressing (TK+) cancer cells and nude mice bearing TK+ tumors. In vitro and in vivo enzyme assays were performed using TK+ cells and tumors. The phosphorylation of ACV monophosphate (ACV-MP) was measured in TK- cell lysates. The pharmacokinetics of prodrugs was evaluated by calculating area-under-the-concentration-time-curve values. RESULTS SDC stimulated HSV-TK activity in TK+ cells and tumors, and increased GCV-TP levels, while no effect of SDC was observed on the phosphorylation of ACV-MP to ACV-TP by cellular kinases. The SDC/prodrug combination altered the pharmacokinetics of the prodrugs. In accord with these findings, SDC enhanced significantly the cell-killing activity of prodrugs. The bystander effect was also significantly augmented by the combined treatment of ACV/GCV and SDC. CONCLUSIONS SDC was shown to be effective in the HSV-TK/prodrug administration system and improved the efficiency of the bystander effect of ACV and GCV. The findings will be considerably valuable with respect to the use of GCV in lower doses and less toxic ACV. This novel strategy of drug combination could provide benefit to HSV-TK/prodrug gene therapy.
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Affiliation(s)
- Kyoko Hayashi
- Department of Virology, University of Toyama, Toyama 930-0194, Japan.
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Tanmahasamut P, Sidell N. Up-regulation of gap junctional intercellular communication and connexin43 expression by retinoic acid in human endometrial stromal cells. J Clin Endocrinol Metab 2005; 90:4151-6. [PMID: 15811935 DOI: 10.1210/jc.2004-0663] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Gap junctions, made up of connexins (Cxs), play fundamental roles in coordinating a number of cellular processes through their ability to directly regulate cell-cell communication. Cx43 is the most widely expressed Cx in the endometrium and is known to be important in a variety of physiological and pathological processes in this tissue. OBJECTIVE In this study, we investigated the ability of the retinoid, all-trans-retinoic acid (RA), to regulate Cx43 expression in human endometrial stromal cells. DESIGN Primary endometrial stromal cells obtained from patients undegoing surgery for infertility workup were treated in vitro with RA and control compounds for different time periods, up to 48 h. Cx43 mRNA and protein levels, protein phosphorylation, and gap junctional intercellular communication (GJIC) were analyzed. RESULTS Treatment of the cells with RA showed a dose-dependent increase in Cx43 expression at both the mRNA and protein levels. In addition, RA induced a relative decrease in the phosphorylated species of Cx43 while causing a corresponding increase in the nonphosphorylated form. Concomitant with these changes, RA-treated cells demonstrated up to a 250% enhancement of GJIC as assessed by dye transfer experiments. Augmentation of GJIC and alterations of Cx43 expression were observed over the same range of RA concentrations. Treatment of cells with the protein kinase C activator 12-O-tetradecanoylphorbol-13-acetate increased the phosphorylated species of Cx43 and correspondingly inhibited GJIC. CONCLUSIONS Phosphorylation of Cx43 is inversely related to GJIC in endometrial stromal cells. Retinoids increase GJIC in endomentrial stromal cells through upregulation of Cx43 expression while inducing a decrease in the phosphorylated species of the protein. The data suggest a novel mechanism by which retinoids can influence endometrial cell biology.
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Affiliation(s)
- Prasong Tanmahasamut
- Division of Research, Department of Gynecology and Obstetrics, Emory University School of Medicine, 1639 Pierce Drive, Atlanta, Georgia 30322, USA
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Field JML, Tate LA, Chipman JK, Minchin SD. Identification of functional regulatory regions of the connexin32 gene promoter. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1628:22-9. [PMID: 12850269 DOI: 10.1016/s0167-4781(03)00111-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Connexin32 (Cx32) is the predominant gap junction protein expressed in adult rat hepatocytes. This study investigated transcriptional regulation of the rat Cx32 gene in MH(1)C(1) rat hepatoma cells using transient expression assays in conjunction with promoter mutagenesis and 5' nested deletion analysis. Site-directed mutagenesis of the -736 and -187 hepatocyte nuclear factor-1 (HNF-1) sites, the -196 and -116 Sp1 sites, and the -729 and -329 Yin Yang 1 (YY1) sites all significantly reduced promoter activity. We have defined the contribution of each individual site to promoter activity in the intact cell. A novel upstream region of the Cx32 promoter (-1042 to -758) was cloned and shown to contain negative regulatory elements. The transcription factors HNF-1 and Sp1 have important functional roles in the transcriptional regulation of basal and cell-specific Cx32 expression. The multifunctional transcription factor YY1 is also implicated.
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Affiliation(s)
- Joanne M L Field
- School of Biosciences, The University of Birmingham, Edgbaston, B15 2TT, Birmingham, UK
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Sáez CG, Velásquez L, Montoya M, Eugenín E, Alvarez MG. Increased gap junctional intercellular communication is directly related to the anti-tumor effect of all-trans-retinoic acid plus tamoxifen in a human mammary cancer cell line. J Cell Biochem 2003; 89:450-61. [PMID: 12761879 DOI: 10.1002/jcb.10519] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Additive effects against tumor cells might be achieved by combining anti-neoplastic agents directed against one or more altered mechanisms in cancer. We investigated the participation of gap junctional intercellular communication (GJIC), which is commonly dysfunctional in tumor cells as a possible mediating mechanism of the effect of all-trans-retinoic acid (RA) and tamoxifen (Tx) in MCF-7 human breast cancer cell lines. The combination of RA + Tx stimulated GJIC in approximately 53 +/- 3% of MCF-7 cells as early as after 6 h of treatment remaining communicated through 144 h of culture. The GJIC enhancement occurred along with immunolocalization of Cx26 and 43 at the membrane of contacting cells and correlated with higher protein levels. Cx40 immunoreactive plaques were detected at cell-to-cell contacts during 48 h of RA + Tx treatment that did not involve higher protein expression, to the contrary, a downregulation occurred after 72 h of treatment. Cell proliferation inhibition upon RA + Tx exposure was observed with optimal effects at 96-120 h of culture with an accumulation of cells primarily in G2/M and G0/G1 cell cycle boundaries. An enhancement of the pre-existing E-cadherin levels was observed after drug exposure along with a downregulation of Bcl-2 and C-myc protein levels and a reduction of telomerase activity, suggesting partial tumor phenotype reversion. Blockage of the RA + Tx-induced GJIC with 18-beta-glycyrrhetinic acid (beta-Gly) prevented in 34% the inhibition of MCF-7 proliferation and the E-cadherin increment in 30% at 96 h of culture. GJIC blockage did not alter the downregulation of Bcl-2, c-Myc, or telomerase activity induced by RA + Tx. Our results showed the participation of GJIC as a mediator mechanism of the combined action of RA and Tx in MCF-7 cells. The chemopreventive modulation of GJIC might represent an approachable alternative for the improvement of cancer therapy.
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Affiliation(s)
- Claudia G Sáez
- Departamento de Hematología-Oncología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
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Li S, Nomata K, Hayashi T, Noguchi M, Kanda S, Kanetake H. Transient decrease in gap junction expression during compensatory renal growth in mice. Urology 2002; 60:726-30. [PMID: 12385951 DOI: 10.1016/s0090-4295(02)01837-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To examine gap junction expression during compensatory renal growth. Compensatory renal growth is a normal response to the removal of renal cells. Gap junctional intercellular communication plays important roles in homeostatic regulation, differentiation, and synchronization of cellular electronic and metabolic functions. METHODS The right ureters of 5-week-old ddy mice were dorsally incised and unilaterally obstructed, and the animals were killed at varying intervals. The control group underwent a sham operation. Freeze-fractured kidney tissue samples were studied using electron microscopy. The amount of proliferative cell nuclear antigen-positive cells and connexin 43 (Cx43) protein was studied by immunohistochemistry and Western blotting, respectively. RESULTS Proliferative cell nuclear antigen-positive cells in the renal tubules increased on days 1 and 2 after surgery that obstructed the ureter, and decreased to normal levels by day 14. The number of gap junctions significantly decreased on days 1 and 2, and then gradually increased to normal levels from days 3 to 14 after surgery. The amount of Cx43 protein in the renal tubules decreased until day 2 and recovered to the same level as that of the control by day 14 after surgery. Significantly, a hyperphosphorylated band of Cx43 in the control kidney was not detected in the operated kidney. CONCLUSIONS These data suggest that the gap junctional intercellular communication of renal tubular cells during compensatory renal growth after unilateral ureteral obstruction could be temporarily reduced concomitant with a decrease of the expression of a phosphorylated Cx43 protein in renal cortical tubular cells after unilateral ureteral obstruction of the contralateral kidney.
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Affiliation(s)
- Shengwen Li
- Department of Urology, Nagasaki University School of Medicine, Nagasaki, Japan
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Hayashi K, Hayashi T, Sun HD, Takeda Y. Contribution of a combination of ponicidin and acyclovir/ganciclovir to the antitumor efficacy of the herpes simplex virus thymidine kinase gene therapy system. Hum Gene Ther 2002; 13:415-23. [PMID: 11860708 DOI: 10.1089/10430340252792549] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
We have previously reported that ponicidin (PND), isolated from Rabdosia ternifolia, potentiates the cell-killing activity of antiherpes prodrugs acyclovir (ACV) and ganciclovir (GCV) in human cancer cells expressing herpes simplex virus thymidine kinase (HSV-TK). To extend these in vitro results to in vivo situations, HSV-TK-expressing HeLa cells were injected into nude mice. The in vivo growth of TK(+) HeLa cells was significantly inhibited by coadministration of PND and ACV, or of PND and GCV, compared with single use of ACV or GCV in spite of lower doses of 1 or 0.25 mg/mouse, respectively. These results indicate that there is a good correlation between this in vivo efficacy and previously reported in vitro efficacy. Because of the insufficiency of incorporation of genes into tumors, bystander cell killing has attracted special interest. In the present study, we determined the ability of PND to potentiate the bystander effects of ACV and GCV in both in vitro and in vivo systems. In vitro combined use of PND with ACV or GCV rendered tumor cells more sensitive to the prodrugs, demonstrating a 1.8- to 97-fold or 2.8- to 26-fold reduction in IC(50) compared with ACV or GCV only, respectively, in 1 to 20% of HSV-TK(+) cells. In the in vivo experiments using nude mice injected with 3 or 10% HSV-TK(+) cells, tumor volume was lower in mice treated with a combination of PND and ACV/GCV than in those treated with ACV or GCV only. No toxicity of PND was seen in mice even at a dose 10-fold higher than that used in the in vivo experiments. These novel strategies could provide benefit to ablative cancer gene therapy by making it feasible to use toxic GCV at lower doses and relatively nontoxic ACV.
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Affiliation(s)
- Kyoko Hayashi
- Department of Virology, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.
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Huang R, Liu YG, Lin Y, Fan Y, Boynton A, Yang D, Huang RP. Enhanced apoptosis under low serum conditions in human glioblastoma cells by connexin 43 (Cx43). Mol Carcinog 2001; 32:128-38. [PMID: 11746825 DOI: 10.1002/mc.1072] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Connexin 43 (Cx43), a structural component of gap junctions, is believed to function as a tumor suppressor gene. Previously, we showed that expression of Cx43 suppresses cell proliferation and tumorigenicity of human glioblastoma cells [Huang et al., Cancer Res 58:5089-5096, 1998] and enhances apoptosis in response to chemotherapeutic agents [Huang et al., Int J Cancer 92:130-138, 2001]. In the present study, we demonstrated that expression of Cx43 in human glioblastoma cells potentiated an apoptotic program under low-serum conditions. The Cx43-mediated effect was coupled with a decreased expression of the specific apoptosis-inhibitor bcl-2. Overexpression of bcl-2 in Cx43-transfected cells conferred resistance to apoptosis induced under low-serum conditions, suggesting that the Cx43-mediated apoptosis under low-serum conditions is regulated, in part, through the downregulation of bcl-2 expression. Furthermore, application of the phosphatidylinositol-3'-OH kinase inhibitor LY294002 specifically induced apoptosis in Cx43-transfected cells. Our results demonstrate a new role of Cx43 in the mediation of apoptosis under low serum conditions.
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Affiliation(s)
- R Huang
- Division of Research, Department of Gynecology and Obstetrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Fang MZ, Mar WC, Cho MH. Cadmium-induced alterations of connexin expression in the promotion stage of in vitro two-stage transformation. Toxicology 2001; 161:117-27. [PMID: 11295261 DOI: 10.1016/s0300-483x(01)00344-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
During the multistage carcinogenesis, functions of several key genes involved in the cell cycle control and cell-cell communication can be damaged. Gap junction intercellular communication (GJIC) is known to transfer small, water-soluble molecules through intercellular channels composed of proteins called connexins (Cxs). Therefore, aberrant expression of Cx may be one of the critical factors for the clonal expansion of initiated cells during the two-stage transformation. We already improved the classical in vitro two-stage transformation method using N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) as an initiator and cadmium as a promoter on Balb/3T3 A31 cells, and reconfirmed the promotional effect of cadmium with this method (Fang, M.Z., Cho, M.H., Lee, H.W., 2001. Improvement of in vitro two-stage transformation assay and detection of the promotional effect of cadmium, Toxicol. In Vitro (in press). In this study, precise roles of Cd on Cx expression in normal Balb/3T3 A31 and during the promotion stage of the in vitro two-stage transformation were elucidated. For this purpose, the Cx43, Cx32 and Cx26 protein levels, Cx43 and Cx26 mRNA levels and the cellular distribution location of Cx43 protein were determined. Normal Balb/3T3 cells expressed Cx43 and Cx32, but not Cx26. After a short-term treatment of cadmium on normal cells, phosphorylation of Cx43 protein increased and Cx32 protein level decreased. However, during the promotion stage of the in vitro two-stage transformation, transformed cells treated with cadmium for long periods expressed Cx43 and Cx32 highly, similar to the level of normal Balb/3T3 cells, compared to the nontransformed cells. Moreover, Cx43 of the transformed cells was distributed mostly in the perinuclear region rather than the intercellular membrane. These data suggest that cadmium may inhibit the GJIC by increasing the phosphorylation of Cx43 and decreasing the expression of Cx32 in the normal Balb/3T3 A31 cells. Our results also suggest that these changes are not associated with the cell transformation; transformed cells may reexpress Cx43 and Cx32 similar to the normal cells, though Cx43 protein is distributed aberrantly during the transformation process. Further studies are needed to clarify the relationship between transformation and posttranslational modification of the Cx proteins.
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Affiliation(s)
- M Z Fang
- School of Agricultural Biotechnology, Seoul National University, 441-744, Suwon, South Korea
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Zhang DQ, McMahon DG. Direct gating by retinoic acid of retinal electrical synapses. Proc Natl Acad Sci U S A 2000; 97:14754-9. [PMID: 11114157 PMCID: PMC18991 DOI: 10.1073/pnas.010325897] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Retinoic acid (RA), a signaling molecule derived from vitamin A, controls growth and differentiation of a variety of cell types through regulation of gene transcription. In the vertebrate retina, RA also regulates gap junction-mediated physiological coupling of retinal neurons through a nontranscriptional mechanism. Here we report that RA rapidly and specifically modulates synaptic transmission at electrical synapses of cultured retinal horizontal cells through an external RAR(beta)(/gamma)-like binding site, the action of which is independent of second messenger cascades. External application of all-trans retinoic acid (at-RA) reversibly reduced the amplitude of gap junctional conductance in a dose-dependent manner, but failed to affect non-gap-junctional channels, including glutamate receptors. In contrast, internal dialysis with at-RA was ineffective, indicating an external site of action. Selective RAR(beta)(/gamma) ligands, but not an RAR(alpha)-selective agonist, mimicked the action of at-RA, suggesting that gating of gap junctional channels is mediated through an RAR(beta)(/gamma)-like binding site. At-RA did not act on gap junctional conductance by lowering [pH](i) or by increasing [Ca(2+)](i). A G protein inhibitor and protein kinase inhibitors did not block at-RA uncoupling effects indicating no second messenger systems were involved. Direct action of at-RA on gap junction channels was further supported by its equivalent action on whole-cell hemi-gap-junctional currents and on cell-free excised patch hemichannel currents. At-RA significantly reduced single-channel open probability but did not change unitary conductance. Overall, the results indicate that RA modulates horizontal cell electrical synapses by activation of novel nonnuclear RAR(beta)(/gamma)-like sites either directly on, or intimately associated with, gap junction channels.
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Affiliation(s)
- D Q Zhang
- Department of Physiology, University of Kentucky, 800 Rose Street, Lexington, KY 40536, USA
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