Validation of target proteins of down-regulated miR-221-5p in HeLa cells treated with Polyalthia longifolia leaf extract using label-free quantitative proteomics approaches.

The current study was conducted to validate the target proteins of down-regulated miR-221-5p in HeLa cells treated with P. longifolia leaf extract. The validation was done by label-free quantitative proteomics approaches, Gene Ontology (GO) and protein–protein interaction analyses after the cells transfected with miRNA mimics or miRNA inhibitor. The LC–ESI–MS/MS identified a total of 1061, 668, 564 and 940 proteins from untransfected and untreated HeLa cells, untransfected P. longifolia leaf extract-treated HeLa cells, miR-221-5p mimic-transfected P. longifolia leaf extract-treated HeLa cells and anti-miR-221-5p-transfected P. longifolia leaf extract-treated HeLa cells, respectively. The proteomic, GO and protein–protein interaction analyses showed that P. longifolia treatment regulated various protein expressions in HeLa cells, namely tropomyosin, PRKC apoptosis WT1 regulator protein (PAWR), alpha-enolase and beta-enolase, which induced apoptotic cell death after the down-regulation of miR-221-5p. Conclusively, this study showed P. longifolia leaf extract’s vital contribution in regulating various protein expressions in HeLa cervical cancer cells to induce apoptotic cell death after downregulation miR-221-5p.