title: pRb-expressing adenovirus Ad5-Rb attenuates the p53-induced apoptosis in cervical cancer cell lines.
abstract: The retinoblastoma protein (pRb), the gene product of the first reported tumour suppressor gene, is functionally inactivated by the E7 protein of high-risk human papillomavirus (HPV) found in most human cervical cancers. We have, in this study, constructed an adenoviral vector expressing wild-type pRb (Ad5-Rb) and used the constructed Ad5-Rb to transfect the osteosarcoma cell line Saos-2, and three cervical cancer cell lines HeLa, SiHa and C-33A. Our results showed that pRb caused G1 arrest in Saos-2 cells after transfection with Ad5-Rb. The number of colonies formed by the Ad5-Rb-transfected Saos-2 cells in soft agar was also found to be significantly lower (P<0.05) than those transfected with the adenoviral control expressing Escherichia coli beta-galactosidase (Ad5-LacZ). The transfection of Ad5-Rb caused an increase in the population of SiHa and C-33A cells in the G1 phase from 53.0 and 52.9% to 72.4 and 64.3%, respectively, but not in the HeLa cells. However, Ad5-Rb did not show any inhibitory effect on the growth of SiHa, HeLa and C-33A cells, and inhibition of colony formation in soft agar was not observed either. In contrast, flow cytometric analysis showed that Ad5-p53, a p53-expressing adenovirus, induced apoptosis, i.e. the appearance of sub-G1 peak, in all three tested cervical cancer cell lines. Nevertheless, the Ad5-p53-induced apoptosis was partially inhibited when Ad5-Rb was added simultaneously. These findings suggested that pRb may not be a good candidate for cervical cancer gene therapy. Our data also showed that the use of full-length pRb in combination with TP53 might not be a suitable strategy for cancer gene therapy.
authors.affiliation: Department of Obstetrics and Gynecology, Faculty of Medicine, The University of Hong Kong, Hong Kong, China.
authors.forename: S M
authors.initials: SM
authors.lastname: Ip
authors.forename: T G
authors.initials: TG
authors.lastname: Huang
authors.forename: W S
authors.initials: WS
authors.lastname: Yeung
authors.forename: H Y
authors.initials: HY
authors.lastname: Ngan
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D017209:Apoptosis / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D005434:Flow Cytometry; D016158:Genes, p53 / Q000235:genetics*; D005822:Genetic Vectors / Q000235:genetics; D006801:Humans; D012516:Osteosarcoma / Q000473:pathology*; D016160:Retinoblastoma Protein / Q000235:genetics*; D014162:Transfection / Q000379:methods; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000502:physiology; D002583:Uterine Cervical Neoplasms / Q000235:genetics / Q000473:pathology*
chemical_list: D004273:DNA, Neoplasm; D016160:Retinoblastoma Protein; D016159:Tumor Suppressor Protein p53