title: SV40 T/t-common polypeptide specifically induces apoptosis in human cancer cells that overexpress HER2/neu.
abstract: Previously, we reported that SV40 T/t-common polypeptide, which contains the NH(2)-terminal common domain of SV40 large T and small t antigens, can repress HER2/neu (also known as erbB-2) expression and consequently suppress the tumorigenic potential of the HER2/neu-overexpressing ovarian carcinoma cells. Here we report that T/t-common could specifically induce apoptosis in HER2/neu-overexpressing human cancer cell lines but not in nontransformed cell lines and HER2/neu low-expressing human cancer cell lines. The ability of T/t-common to induce apoptosis in HER2/neu-overexpressing cancer cells was derived from its ability to inhibit HER2/neu because reexpression of a large amount of HER2/neu could block apoptosis induced by T/t-common. T/t-common expression in HER2/neu-overexpressing SK-OV-3 cancer cells led to down-regulation of Bcl-2 and Bcl-X(L), and overexpression of Bcl-2 could inhibit the ability of T/t-common to induce apoptosis in these cells. Therefore, the apoptosis-inducing activity of T/t-common is related to its ability to inhibit Bcl-2 expression in HER2/neu-overexpressing cancer cells. Consistent with the apoptosis-inducing activity of T/t-common, we found that T/t-common could specifically inhibit the soft-agarose colony-forming ability of the HER2/neu-overexpressing human cancer cell lines but not that of the HER2/neu low-expressing human cancer cell lines. Finally, we showed that T/t-common could specifically sensitize HER2/neu-overexpressing human cancer cell lines, but not HER2/neu low-expressing human cancer cell lines, to chemotherapeutic agent etoposide. Together, these data suggest that T/t-common alone or in combination with chemotherapy may provide a new approach for treatment of cancers that overexpress HER2/neu.
authors.affiliation: Graduate Institute of Microbiology, College of Medicine, National Taiwan University, Taipei, Taiwan, USA.
authors.forename: Chun-Chiang
authors.initials: CC
authors.lastname: Wen
authors.forename: Shih-An
authors.initials: SA
authors.lastname: Cheng
authors.forename: Shu-Ping
authors.initials: SP
authors.lastname: Hsuen
authors.forename: Ya-Ling
authors.initials: YL
authors.lastname: Huang
authors.forename: Zong-Keng
authors.initials: ZK
authors.lastname: Kuo
authors.forename: Hsin-Fang
authors.initials: HF
authors.lastname: Lee
authors.forename: Chou-Hua
authors.initials: CH
authors.lastname: Kuo
authors.forename: Jia-Ling
authors.initials: JL
authors.lastname: Du
authors.forename: Won-Bo
authors.initials: WB
authors.lastname: Wang
mesh_terms: D000952:Antigens, Polyomavirus Transforming / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D015316:Genetic Therapy / Q000379:methods; D006367:HeLa Cells; D006801:Humans; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D017434:Protein Structure, Tertiary; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D014162:Transfection
chemical_list: D000952:Antigens, Polyomavirus Transforming; D051017:Apoptosis Regulatory Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases