Antiproliferative potential of piperine and curcumin in drug-resistant human leukemia cancer cells are mediated via autophagy and apoptosis induction, S-phase cell cycle arrest and inhibition of cell invasion and migration.

Purpose Leukemia causes annually a significant number of deaths. The main objective of this study was to investigate the anticancer properties of piperine and curcumin against HL60 leukemia cells and to elucidate the underlying mechanism. Methods Antiproliferative effects were assessed by WST-1 cell viability assay. Cell apoptotic effects were studied by DAPI staining assay. Annexin V/propidium iodide (PI) assay was used to assess apoptosis. Electron microscopy was used for detection of autophagy and flow cytometry for cell cycle analysis, while transwell migration assay was used to study the effects on cell migration and invasion. Protein expression was estimated by western blot. Results The results showed that both piperine and curcumin inhibited significantly the growth of the HL60 cells and exhibited an IC50 of 25 and 30 µM respectively. Further, it was observed that the anticancer effects of piperine and curcumin were due to the induction of mitochondrial-mediated apoptosis which was also associated with enhancement of the Bax expression. Transmission electron microscopy also showed that both curcumin and piperine induced autophagy in the HL-60 leukemia cells. Flow cytometry showed that piperine and curcumin also caused arrest of the HL-60 cells at the S-phase of the cell cycle. Finally wound healing and transwell assays showed that piperine and curcumin suppressed the migration and invasive potential of the HL60 cells. Conclusions The present study reveals that piperine and curcumin exhibit significant antitumor activity in human leukemia HL60 cells via multiple mechanisms and may prove promising in the development of systemic therapy for leukemia.