An anti-oncogenic action of the polyomavirus large-T (LT) antigen in HeLa and SiHa tumor cells.
HeLa (HPV-18) and SiHa (HPV-16) cell lines were transfected with the plasmid LTneo. Two new phenotypes cells, called, HLT and SLT, respectively, were propagated in culture after the transfection by calcium phosphate precipitation procedure, followed by G-418 selection. We noticed that in vitro characteristics of both cell lines HeLa and SiHa are affected by transfection of the LT gene into their genome: HLT and SLT growth rate decreased in culture compared to their parental cell lines HeLa and SiHa; HLT and SLT observed under the microscope appeared markedly different but similar to normal cervical epithelium; HLT and SLT are not able to grow in semi-solid medium; they are anchorage-dependent. Investigation of in vivo properties of HLT and SLT was done by injection in 1-month-old nude mice; they are not able to produce tumors. In conclusion, the genetic transfection of HeLa and SiHa with the immortalizing gene decreases the cancerous properties of both cell lines in vitro as well as in vivo. In this context, LT functions as an anti-oncogene, a growth-regulatory protein. This would seem to conflict with its function as an oncogene in the multiple step carcinogenic process.
Ratiarson
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Department of Biology, Laurentian University, Sudbury, Ontario, Canada.
D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D002455:Cell Division; D016147:Genes, Tumor Suppressor; D005814:Genes, Viral; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D027383:Papillomaviridae / Q000235:genetics*; D014407:Tumor Cells, Cultured / Q000473:pathology*
D000952:Antigens, Polyomavirus Transforming