Hsa_circ_0003998 promotes chemoresistance via modulation of miR-326 in lung adenocarcinoma cells.

Circular RNAs (circRNAs) represent a new class of non-coding RNAs that is involved in the development of cancer. However, little is known about their role in chemoresistance. In the present study, we found that hsa_circ_0003998 expression levels in lung adenocarcinoma (LAD) tissues and docetaxel-resistant cell lines (A549/DTX and H1299/DTX) were upregulated. Knockdown of hsa_circ_0003998 decreased chemoresistance, inhibited proliferation, and enhanced apoptosis in docetaxel-resistant LAD cells. Moreover, by using bioinformatics and luciferase reporter assays, we found that miR-326 was a direct target of hsa_circ_0003998. Functional analysis revealed that miR-326 mediated the effect of hsa_circ_0003998 on chemosensitivity. Our findings provide a molecular insight on understanding drug resistance in LAD cells. Therefore, inactivation of hsa_circ_0003998 or activation of miR-326 could be a novel approach for the treatment of LAD.