MicroRNAs (miRNAs) play a key role in the regulation of gene expression. In this study, we demonstrate that microRNA-19a and -19b (miR-19a/b) are highly expressed in human cervical cancer cells and are involved in maintaining the malignant phenotypes of HeLa and C33A cells. Up-regulation of miR-19a and miR-19b promoted cell growth and invasion, whereas knockdown of miR-19a and miR-19b yielded the reverse phenotype. CUL5 was identified as a novel target gene of both miR-19a and miR-19b. CUL5 ectopic over-expression without its 3' untranslated region (UTR) abolished the effect of miR-19a/b on HeLa and C33A cell proliferation and invasion. These results indicated that miR-19a/b directly and negatively regulate CUL5 expression in cervical cancer cells, highlighting the importance of miR-19a and miR-19b and their target genes in tumorigenesis.
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