Abstracts

Cervical cancer is the third leading cause ofmorbidity in female cancers. Persistent infection of high-risk typehuman papillomavirus (HPV) is a prerequisite of cervical cancerdevelopment. Nevertheless, chronic HPV infection is inadequate toinduce cervical cancer formation while additional endogenous orexogenous cues are needed with chronic HPV-infection to causecervical cancer. Stimulation of the Wnt/-catenin signaling pathwayhas been demonstrated to enhance the tumorigenecity of the cervicalcancer cell lines, and is also able to transform HPV-infectedkeratinocytes into cancer cells. Aberrant microRNA (miRNA)expression is one the commonest factors leading to cervical cancerformation. MiR-135a is an oncogenic miRNA that transformsHPV-immortalized cervical epithelial cells to cancer cells. It wasdemonstrated that miR-135a triggers transformation by activation ofthe Wnt/-catenin signaling pathway through suppressing theWnt/-catenin negative regulator SIAH1. A single miRNA can suppressmany genes and affects multiple pathways; however, the summationeffect of miR-135a in cervical carcinogenesis was unknown. Besides,the molecular events occurred during miR-135a inducedtransformation was unclear. In this study, in order toinvestigate the molecular events occurred during miR-135a mediatedtransformation, an HPV immortalized non-carcinogenic cervicalepithelial cell line NC104-E6E7 has been adopted as a model of thestarting point of the transformation process. MiR-135a wasforce-expressed in the NC104-E6E7 cells by serial transientforce-expression of miR-135a. The tumorigenic properties (invasion,migration, cell cycle progression and the percentage of CD133^+subpopulation) of the miR-135a force-expressed cells were examinedduring the serial force-expression process. It was obvious that thetumorigenicity of the cells increased with increasing number ofmiR-135a force-expression. Such transformation process wasaccompanied by the initiation of epithelial-mesenchymal transition(EMT), when the markers E-cadherin decreased and N-cadherinincreased their expression within this process. Moreover, the cellsexperienced 3 and 5 times of miR-135a force-expression couldgenerate tumors in severe combined immunodeficiency (SCID) micewhile the tumors formed from 5 time of miR-135 force-expressedcells are larger. The expression profile of the seriallytransfected cell lines was determined by microarray analysis.Compared with the parent cell line NC104-E6E7, the miR-135aserially force-expressed cell lines 1#135a, 3#135a and 5#135aexperienced the activation of the carcinogenic signaling pathways,such as ECM-receptor interaction, pathways in cancer and Toll-likereceptor signaling pathway. Meanwhile, several genes relates totumor formation have been differentially expressed. We validatedthe expression of CXCL14, ITGB6, FGF2 and IL-8 through quantitativepolymerase chain reactions (qPCRs). Results of qPCRs were similarto that observed in microarray analysis. In the seriallytransfected cell