Abstract
Connexins are a family of transmembrane proteins essential for the gap junctions, which mediate cell-to-cell communication. Several connexins are reported to be tumor suppressors, and we have established transgenic (Tg) rats with a connexin 32 (Cx32) dominant negative mutant showing high sensitivity to early-stage diethylnitrosamine (DEN)-induced liver carcinogenesis. In this study, we carried out two independent experiments using Tg rats to further investigate the roles of disrupted Cx32 in late-stage carcinogenesis (carcinoma induction and metastasis) in the liver. In the first experiment, of 50 weeks’ duration, DEN was administered at 6 weeks of age and at 26 weeks to explore the effects of carcinogen treatments at different stages. The number of hepatocellular carcinomas (HCCs) was significantly increased in Tg compared with non-Tg rats. The second experiment focused on the effects of Cx32 disruption on metastasis by HCCs induced by administration of DEN and N-nitrosomorpholine. Only Tg rats had multiple metastases of HCCs in the lung, and the development and growth of HCCs was dramatically accelerated in Tg compared to non-Tg rats. Thus, normal function of Cx32 may be essential for suppression of both early and late stages of hepatocarcinogenesis.
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Asamoto M, Hokaiwado N, Murasaki T, Shirai T (2004) Connexin 32 dominant-negative mutant transgenic rats are resistant to hepatic damage by chemicals. Hepatology 40:205–210
Dagli ML, Yamasaki H, Krutovskikh V, Omori Y (2004) Delayed liver regeneration and increased susceptibility to chemical hepatocarcinogenesis in transgenic mice expressing a dominant-negative mutant of connexin32 only in the liver. Carcinogenesis 25:483–492
Evert M, Ott T, Temme A, Willecke K, Dombrowski F (2002) Morphology and morphometric investigation of hepatocellular preneoplastic lesions and neoplasms in connexin32-deficient mice. Carcinogenesis 23:697–703
Futakuchi M, Hirose M, Ogiso T, Kato K, Sano M, Ogawa K, Shirai T (1999) Establishment of an in vivo highly metastatic rat hepatocellular carcinoma model. Jpn J Cancer Res 90:1196–1202
Hokaiwado N, Asamoto M, Ogawa K, Shirai T (2005) Transgenic disruption of gap junctional intercellular communication enhances early but not late stage hepatocarcinogenesis in the rat. Toxicol Pathol 33:695–701
King TJ, Bertram JS (2005) Connexins as targets for cancer chemoprevention and chemotherapy. Biochim Biophys Acta 1719:146–160
King TJ, Lampe PD (2004) The gap junction protein connexin32 is a mouse lung tumor suppressor. Cancer Res 64:7191–7196
Krutovskikh VA, Oyamada M, Yamasaki H (1991) Sequential changes of gap-junctional intercellular communications during multistage rat liver carcinogenesis: direct measurement of communication in vivo. Carcinogenesis 12:1701–1706
Lee HJ, Lee IK, Seul KH, Rhee SK (2002) Growth inhibition by connexin26 expression in cultured rodent tumor cells. Mol Cells 14:136–142
Mesnil M, Crespin S, Avanzo JL, Zaidan-Dagli ML (2005) Defective gap junctional intercellular communication in the carcinogenic process. Biochim Biophys Acta 1719:125–145
Moennikes O, Buchmann A, Romualdi A, Ott T, Werringloer J, Willecke K, Schwarz M (2000) Lack of phenobarbital-mediated promotion of hepatocarcinogenesis in connexin32-null mice. Cancer Res 60:5087–5091
Moennikes O, Stahl S, Bannasch P, Buchmann A, Schwarz M (2003) WY-14,643-mediated promotion of hepatocarcinogenesis in connexin32-wild-type and connexin32-null mice. Carcinogenesis 24:1561–1565
Nelles E, Butzler C, Jung D, Temme A, Gabriel HD, Dahl U, Traub O, Stumpel F, Jungermann K, Zielasek J, Toyka KV, Dermietzel R, Willecke K (1996) Defective propagation of signals generated by sympathetic nerve stimulation in the liver of connexin32-deficient mice. Proc Natl Acad Sci USA 93:9565–9570
Oyamada M, Oyamada Y, Takamatsu T (2005) Regulation of connexin expression. Biochim Biophys Acta 1719:6–23
Sakamoto H, Oyamada M, Enomoto K, Mori M (1992) Differential changes in expression of gap junction proteins connexin 26 and 32 during hepatocarcinogenesis in rats. Jpn J Cancer Res 83:1210–1215
Temme A, Buchmann A, Gabriel HD, Nelles E, Schwarz M, Willecke K (1997) High incidence of spontaneous and chemically induced liver tumors in mice deficient for connexin32. Curr Biol 7:713–716
Trosko JE, Chang CC (2001) Mechanism of up-regulated gap junctional intercellular communication during chemoprevention and chemotherapy of cancer. Mutat Res 480–481:219–229
Trosko JE, Ruch RJ (2002) p junctions as targets for cancer chemoprevention and chemotherapy. Curr Drug Targets 3:465–482
Tsuda H, Asamoto M, Baba H, et al. (1995) Cell proliferation and advancement of hepatocarcinogenesis in the rat are associated with a decrease in connexin 32 expression. Carcinogenesis 16:101–105
Willecke K, Eiberger J, Degen J, Eckardt D, Romualdi A, Guldenagel M, Deutsch U, Sohl G (2002) Structural and functional diversity of connexin genes in the mouse and human genome. Biol Chem 383:725–737
Yamasaki H, Omori Y, Zaidan-Dagli ML, Mironov N, Mesnil M, Krutovskikh V (1999) Genetic and epigenetic changes of intercellular communication genes during multistage carcinogenesis. Cancer Detect Prev 23:273–279
Yoshino H, Futakuchi M, Cho YM, Ogawa K, Takeshita F, Imai N, Tamano S, Shirai T (2005) Modification of an in vivo lung metastasis model of hepatocellular carcinoma by low dose N-nitrosomorpholine and diethylnitrosamine. Clin Exp Metastasis 22:441–447
Acknowledgment
We thank Dr. Malcolm A. Moore for his kind linguistic advice during preparation of the manuscript. This study was supported in part by a grant-in-aid from the Japan Health Sciences Foundation, Research on Health Sciences Focusing on Drug Innovation; a grant-in-aid for the Second Term Comprehensive 10-Year Strategy for Cancer Control; and a grant-in-aid for cancer research from the Ministry of Health, Labor and Welfare of Japan, as well as by the Society for Promotion of Pathology (Nagoya, Japan).
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Hokaiwado, N., Asamoto, M., Futakuchi, M. et al. Both Early and Late Stages of Hepatocarcinogenesis Are Enhanced in Cx32 Dominant Negative Mutant Transgenic Rats with Disrupted Gap Junctional Intercellular Communication. J Membrane Biol 218, 101–106 (2007). https://doi.org/10.1007/s00232-007-9053-9
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DOI: https://doi.org/10.1007/s00232-007-9053-9