STAT3 is an important molecule in Janus kinase (JAK) signal transducer and activator of transcription (STAT) signal pathway, and facilitates expression of various oncogenic genes such as Bcl-2, thus is correlated with tumor onset, progression and drug resistance. MiR-29a down-regulation is associated with the pathogenesis of nasopharyngeal carcinoma. Bioinformatics analysis demonstrated a complementary binding between miR-29a and 3'-UTR of STAT3. This study aims to investigate the role of miR-29a in regulating STAT3, as well as in Taxol resistance of nasopharyngeal carcinoma CNE-1 cells. Dual luciferase reporter gene assay showed a regulatory relationship between miR-29a and STAT3. Rhodamine 123 repository in CNE-1 and CNE1/Taxol drug resistant cells was measured together with the expression of miR-29a, STAT3, and p-STAT3. Flow cytometry was used to measure cell apoptosis and PCNA expression under Taxol treatment. CNE-1/Taxol cells were treated with miR-29a mimic and or si-STAT3, followed by measuring the expression of miR-29a, STAT3, and p-STAT3 and cell apoptosis. CCK-8 assay was performed to evaluate cell proliferation. MiR-29a inhibited STAT3 expression. Significantly lower Rhodamine 123 repository, miR-29a expression and apoptosis and higher expression of STAT3, p-STAT3 and PCNA were observed in CNE-2/ Taxol cells than those in CNE-1 cells. Transfection of miR-29a mimic and/or si-STAT3 decreased STAT3, p-STAT3 and PCNA expression, inhibited proliferation and promoted cell apoptosis. MiR-29a down-regulation is correlated with drug resistance of nasopharyngeal carcinoma cell line CNE-1 and MiR-29a up-regulation decreases Taxol resistance of nasopharyngeal carcinoma CNE-1 cells possibly via inhibiting STAT3 and Bcl-2 expression.
Keywords: MiR-29a; STAT3; drug resistance; nasopharyngeal carcinoma; taxol.