Identification of microRNA profile associated with cervical cancer development

Cervical cancer is the third leading cause of cancer death in women worldwide. Although cervical cancer is commonly infected with human papillomavirus (HPV), HPV infection alone is insufficient to induce malignant changes. Many characteristic genetic and epigenetic alterations have been identified in invasive cervical carcinomas but relatively little is known about the specific genetic and molecular alterations that allow pre-invasive epithelial cells to acquire the ability to progress to invasive squamous cell carcinomas. Recently, a family of small non-coding RNAs termed microRNAs (miRNAs) with specific inhibitory functions on target gene expression has been suggested to play an important role in the pathogenesis of human cancers including lung and breast cancer but remain undefined in cervical cancer.;To identify microRNA(s) associated with the tumorigenesis of cervical cancer, we firstly used the TaqMan MicroRNA Assays to survey and quantify a panel of 157 known human miRNAs in cervical cancer cell fines and micro-dissected normal cervical epithelium cells. We identified 2 microRNAs that were differentially up-regulated (fold change > 2, p 2, p < 0.05) in cervical cancer cell lines comparing with normal cervical epithelium. Further investigation in tumor samples confirmed these two up-regulated miRNAs (hsa-miR-182 and -183 ) and 3 down-regulated miRNA (hsa-miR-145, 150, 195) from 4 investigated downregulated miRNAs (hsa-miR-145, 150, 195 and 328).;Genome wide chromosomal copy number changes in cervical cancer by Agilent high-density array Comparative Genomic Hybridization demonstrated that only a very limited number of genomic imbalances have an impact on the miRNA profile in cervical cancer cells, although a high proportion of genomic loci containing miRNA genes exhibited DNA copy number alterations in other cancers. The impact of the genomic aberration on their mRNA expression was then confirmed by Aligent Whole Human Genome gene expression array. This suggests that the regulation of miRNA and mRNA expression may be different in cervical cancer.;To investigate the biological function of those aberrantly expressed microRNAs, we chose one of the most aberrantly up-regulated microRNA ( hsa-miR-182, fold change > 10) for further investigation. Inhibition of hsa-miR-182 by antisense oligonucleotides inhibited HeLa cervical cancer cell growth in vitro and reduced tumor cell volume in vivo. Gene expression array analysis of HeLa cells with hsa-miR-182 knockdown and over-expression showed specific hsa-miR-182 targeting pathway in apoptosis and cell cycle. It indicated the roles of hsa-miR-182 in cervical cancer growth through apoptosis and cell cycle functions.;In conclusion, our global miRNA profiling identified the common differentially expressed and genomic aberration independent miRNAs in cervical cancer. We further revealed the inhibition of hsa-miR-182 reduced tumor cell growth in vitro and in vivo through apoptosis and cell cycle mechanism. This provides new evidence that hsa-miR-182 may contribute to the pathogenesis of cervical cancer.;Keywords. MicroRNA, Cervical Cancer, Tumor Growth.