ABSTRACT
PURPOSE: Transforming growth factor-Bs (TGF-Bs) are prototypic multifunctional negative growth factors that inhibit the growth of many cell types. TGF-B type I and II receptors(RI, RII) are transmembrane receptors containing cytoplasmic serine/ threonine kinase domain and have been implicated in mediating TGF-B activity. Because a heteromeric complex of RI and RII is required for TGF-B signal transduction, cancer cells may reduce the expression of either RI or RII to escape from growth inhibition of TGF-B. We examined the correlation between the growth inhibitory activity of TGF-B1 and the genetic expression of RI &RII genes in human breast cancer cell lines. MATERIALS AND METHODS: We examined the growth inhibitory activity of TGF-B1 in 5 breast cancer cell lines by incorporation of [3H] thymidine. To investigate the correlation between TGF-B1 insensitivity and genetic change of TGF-B receptor genes (RI, RII), Southem blot analysis, Northern blot analysis, and Western blot analysis were performed. We also examined whether microsatellite instability(RER) was associated with RII mutation. RESULTS: We found that 3 breast cancer cell lines (MCF-7, YCC-B101, YCC-B151) were resistant to growth inhibitory effect of TGF-B1. MCF-7 cell line expressed no detectable RII mRNA and RII protein, but showed normal structure of RII gene and normal expression of RI gene. And we did not find any abnormal expression of mRNA, protein, and genetic structure of RI &RII in YCC-B101 and YCC-B151. CONCLUSION: Our results suggest that aquired resistance to the growth inhibitory effect of TGF-B1> could be transcription regulation system of RII in MCF-7 cell line, and could be postreceptor signal transduction pathway in YCC-B101 and YCC-B151 cell lines.
Subject(s)
Humans , Blotting, Northern , Blotting, Western , Breast Neoplasms , Breast , Cell Line , Cytoplasm , Genetic Structures , Intercellular Signaling Peptides and Proteins , MCF-7 Cells , Microsatellite Repeats , Negotiating , Protein Serine-Threonine Kinases , RNA, Messenger , Signal Transduction , Thymidine , United NationsABSTRACT
PURPOSE: To evaluate the effect of wild type p53 gene transduction on the malignant phenotypes for metastasis in gastric cancer, we compared the biological phenpotypes of gastric cancer cell lines based on p53 gene status. Then, after retrovirus-mediated wild-type p53 gene transduction, we compared those phenotypes among parent YCC-3 cell line, vector transduced YCC-3v cell line and a clone of YCC-3C3. MATERIAL AND METHODS: Four human gastric cancer celi lines were used; YCC-l(mutant), YCC-2(wild), YCC-3(mutant) and AGS(wild). DNAs of the cell lines were analyzed to evaluate the mobility shift with PCR-SSCP. Tumorigenecity and proliferation were evaluated by soft agar assay and proliferation assay. Migratory capacity was measured by adhesion assay and Boyden chamber assay. p53 protein expression was measured by Western blot analysis and VEGF, WAF-1 were measured by ELISA assay. Angiogenic activity was measured by cross-feeding assay and cell cycle analysis was performed by flowcytometry. In vivo tumorigenicity was measured by xenograft in nude mice. RESULTS: YCC-3 cell line with mutant p53 gene expressed all the phenotypes for the metastasis such as tumorigenicity, migration and angiogenesis. In a stable clone of YCC-3C3, no differences were found in proliferation, cell cycle and WAP-1 expression when compared to those of the control YCC-3v and parent YCC-3 cell line, even if increased p53 protein production was found by Western blot analysis. However, both in vitro and in vivo tumorigenicity were decreased in a stably transduced YCC-3C3 clone. The adhesive capacity was also decreased in YCC-3C3 clone whereas the endothelial cell growth stimulatory effect and VEGF production showed no difference compared to those of the YCC-3v cell line. CONCLUSION: Wild-type p53 gene transduction in gastric cancer cell line decreased tumorigenicity which resulted from decreased colony forming activity and adhesive capacity but not formed changes of angiogenic activity. This suggested the possible application of anti- metastasis strategy with p53 gene therapy in gastric cancer.