MicroRNAs contribute to the chemoresistance of cisplatin in tongue squamous cell carcinoma lines.

MicroRNAs (miRNAs) are small non-coding RNAs that function as negative regulators of gene expression. They are strongly implicated in human cancers, including oral squamous cell carcinoma (OSCC). Evidence for the involvement of miRNAs as important regulators of chemosensitivity and chemoresistance in OSCC is not well understood. In this study, miRNA microarray was firstly used to compare the differential miRNAs levels between the cisplatin-sensitive tongue squamous cell carcinoma line (Tca8113) and its cisplatin-resistant subline (Tca/cisplatin). Three miRNAs of miR-21, -214, and -23a were validated by miRNAs real-time PCR, and intervened by anti-miRNA oligonucleotides (miR-214 and -23a) and pre-miRNA plasmid transfection (miR-21). Further relationship between miR-23a and DNA topoisomerase II beta (TOP2B) on the chemoresistance against cisplatin was studied. There were 19 out of 480 differential miRNAs between the Tca8113 and Tca/cisplatin cells. miR-214 and -23a were found increased as with chemoresistance against cisplatin in the Tca/cisplatin cells while miR-21 was found decreased as with chemosensitivity for cisplatin in the Tca/cisplatin cells. Intervention of these three miRNAs could decrease the chemoresistance against cisplatin in Tca/cisplatin cells. Transfection of anti-miR-23a into the Tca/cisplatin cells could increase the TOP2B protein expression. Our results suggest the existence of differential miRNAs with chemosensitivity and chemoresistance between the cisplatin-sensitive and resistant tongue squamous cell carcinoma lines. miR-21 serves as a chemosensitive miRNA, while miR-214 and -23a serve as chemoresistant miRNAs in the tongue squamous cell carcinoma lines. miR-23a is an up-stream regulator of TOP2B to realize the chemoresistance of cisplatin.