Effects of HRAS oncogene on cell cycle progression in a cervical cancer-derived cell line.
BACKGROUND
Human papillomavirus (HPV) infection is the most prevalent factor in anogenital cancers. However, epidemiological surveys and molecular data indicate that viral presence is not enough to induce cervical cancer, suggesting that cellular factors could play a key role. One of the most important genes involved in cancer development is the RAS oncogene, and activating mutations in this gene have been associated with HPV infection and cervical neoplasia. Thus, we determined the effect of HRAS oncogene expression on cell proliferation in a cell line immortalized by E6 and E7 oncogenes.


METHODS
HPV positive human cervical carcinoma-derived cell lines (HeLa), previously transfected with the HRAS oncogene or the empty vector, were used. We first determined the proliferation rate and cell cycle profile of these cells by using flow cytometry and BrdU incorporation assays. In order to determine the signaling pathway regulated by HRAS and implicated in the alteration of proliferation of these cells, we used specific chemical inhibitors to inactivate the Raf and PI3K pathways.


RESULTS
We observed that HeLa cells stably transfected with oncogenic HRAS progressed faster than control cells on the cell cycle by reducing their G1 phase. Additionally, HRAS overexpression accelerated the G1/S transition. Specific chemical inhibitors for PI3K and MEK activities indicated that both PI3K/AKT and RAF/MEK/ERK pathways are involved in the HRAS oncogene-induced reduction of the G1 phase.


CONCLUSIONS
Our results suggest that the HRAS oncogene could play an important role in the development of cervical cancer, in addition to the presence of HPV, by reducing the G1 phase and accelerating the G1/S transition of infected cells.
Córdova-Alarcón
Emilio
E
Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México, D.F., México
Centeno
Federico
F
Reyes-Esparza
Jorge
J
García-Carrancá
Alejandro
A
Garrido
Efraín
E
D015153:Blotting, Western; D001973:Bromodeoxyuridine / Q000494:pharmacology; D002453:Cell Cycle; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D004268:DNA-Binding Proteins / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D016193:G1 Phase; D011905:Genes, ras; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000235:genetics; D027383:Papillomaviridae / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D016196:S Phase; D013997:Time Factors; D014162:Transfection; D002583:Uterine Cervical Neoplasms / Q000235:genetics* / Q000473:pathology* / Q000821:virology
D004268:DNA-Binding Proteins; C052603:E6 protein, Human papillomavirus type 18; C052633:E7 protein, Human papillomavirus type 18; D004791:Enzyme Inhibitors; D009856:Oncogene Proteins, Viral; D019869:Phosphatidylinositol 3-Kinases; D001973:Bromodeoxyuridine