The long-term objectives of the project are to determine the role of gap junctional intercellular communication (GJIC) and its control mechanisms in multistage carcinogenesis, and to study how connexin (Cx) genes control cell growth. Dr. Yamasaki now has good evidence that connexin genes form a family of tumor suppressor genes and preliminary results suggest that some human tumors contain mutated connexin genes. He also obtained evidence that mutant connexins inhibit GJIC by a dominant-negative fashion. Although individual cells in vivo usually express two or more specific connexin genes, cultured cells often express only Cx43. Since the data of our own and other laboratories indicate that specific connexin genes exert differential effects, he proposes to use more in vivo models. Based on these results, we propose 1) to study whether cancers have a high prevalence of connexin gene mutations and whether their mutation spectra are associated with exposure to specific carcinogens; 2) to study the dominant-negative effect of mutated connexins on wild-type connexins and its consequence in cell growth control. This will be studied both in cultured cells as well as in rodents by introducing mutated connexin genes driven by a tissue-specific gene promoter. Such dominant-negative transgenes should produce tissue-specific knock-out mice of specific connexin genes; we have already established transgenic mice carrying a mutated Cx32 gene, targeting the liver, and we now plan to target the skin. These mice will be compared with those in which a specific connexin-gene is knocked-out; currently, we have Cx43 knock-out mice, and Cx32 knock-out mice will soon become available. Their response to mutagenic and non-mutagenic carcinogens will be studied; 3) to study whether one connexin species produces heteromeric connexons with another species of connexins and how this may play a role in cell growth control. Most cell types express multiple connexin gene species and our preliminary data suggest that co-expression of the Cx32 gene in HeLa cells, the tumorigenicity of which had been suppressed by Cx26 transfection, resulted in removal of this suppression. Thus, it appears that Cx26/Cx26 connexons are tumor suppressive, but Cx26/Cx32 are not. Dr. Yamasaki proposes to examine the role of multiple connexin gene expression and their heteromeric connexons in cell growth control, employing both in vivo and in vitro models, and 4) to study the mechanisms of cell growth control by connexins. His approaches here include i) the possible role of cell cycle genes known to be associated with cell-cell interaction and ii) the effect on cell adhesion mechanisms; the data suggest that a-catenin expression is associated with connexin gene-mediated growth control.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA040534-12
Application #
2856259
Study Section
Chemical Pathology Study Section (CPA)
Program Officer
Okano, Paul
Project Start
1985-08-01
Project End
1999-12-31
Budget Start
1999-01-01
Budget End
1999-12-31
Support Year
12
Fiscal Year
1999
Total Cost
Indirect Cost
Name
International Agency for Research on Cancer
Department
Type
DUNS #
279551881
City
Lyon
State
Country
France
Zip Code
69008
Tanaka, Toshiaki; Duflot-Dancer, Agnes; Tiraby, Michele et al. (2009) Bystander effect from cytosine deaminase and uracil phosphoribosyl transferase genes in vitro: a partial contribution of gap junctions. Cancer Lett 282:43-7
Dagli, Maria Lucia Zaidan; Yamasaki, Hiroshi; Krutovskikh, Vladimir et al. (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 25:483-92
Loncarek, Jadranka; Yamasaki, Hiroshi; Levillain, Pierre et al. (2003) The expression of the tumor suppressor gene connexin 26 is not mediated by methylation in human esophageal cancer cells. Mol Carcinog 36:74-81
Omori, Y; Zaidan Dagli, M L; Yamakage, K et al. (2001) Involvement of gap junctions in tumor suppression: analysis of genetically-manipulated mice. Mutat Res 477:191-6
Tanaka, T; Yamasaki, H; Mesnil, M (2001) Induction of a bystander effect in HeLa cells by using a bigenic vector carrying viral thymidine kinase and connexin32 genes. Mol Carcinog 30:176-80
Yano, T; Hernandez-Blazquez, F J; Omori, Y et al. (2001) Reduction of malignant phenotype of HEPG2 cell is associated with the expression of connexin 26 but not connexin 32. Carcinogenesis 22:1593-600
Hernandez-Blazquez, F J; Joazeiro, P P; Omori, Y et al. (2001) Control of intracellular movement of connexins by E-cadherin in murine skin papilloma cells. Exp Cell Res 270:235-47
Yano, T; Yamasaki, H (2001) Regulation of cellular invasion and matrix metalloproteinase activity in HepG2 cell by connexin 26 transfection. Mol Carcinog 31:101-9
Yamakage, K; Omori, Y; Zaidan-Dagli, M L et al. (2000) Induction of skin papillomas, carcinomas, and sarcomas in mice in which the connexin 43 gene is heterologously deleted. J Invest Dermatol 114:289-94
Saito, T; Krutovskikh, V; Marion, M J et al. (2000) Human hemangiosarcomas have a common polymorphism but no mutations in the connexin37 gene. Int J Cancer 86:67-70

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