Nobiletin flavone inhibits the growth and metastasis of human pancreatic cancer cells via induction of autophagy, G0/G1 cell cycle arrest and inhibition of NF-kB signalling pathway.

PURPOSE

The anticancer effects of nobiletin have not been fully explored against the human pancreatic cancer cells. Therefore this study was undertaken to evaluate the anticancer effects of nobiletin against the MIAPaCa-2 human pancreatic cancer cells along with evaluating its effects on autophagy, cell cycle phase distribution, cell migration and invasion and NF-kB signalling pathway.

METHODS

Cell proliferation was evaluated by CCK-8 assay while cell cycle analysis was carried out by flow cytometry. Effects on cell migration and invasion were evaluated by wound healing assay and transwell assays respectively. Transmission electron microscopy (TEM) and western blot were used to study the effects on autophagy and NF-kB signalling pathway.

RESULTS

The results revealed that nobiletin restrained the proliferation rate of the MIAPaCa-2 human pancreatic cancer cells and showed an IC50 of 6.12 µM. However, nobiletin exhibited very high IC50 against the normal ms-1 pancreatic cells. TEM showed that nobiletin triggered autophagy in the MIAPaCa-2 cancer cells which was accompanied by enhancement in the expression of LC3B II and LC3-I, and decrease in the expression of p62. Cell cycle analysis showed that nobiletin caused accretion of the MIAPaCa-2 cells in the G0/G1 phase of the cell cycle activating G0/G1 cell cycle arrest. The G0/G1 arrest of MIAPaCa-2 cells was also concomitant with depletion of cyclin D1 and CDK4 expression. Nobiletin suppressed the migration of the MIAPaCa-2 cancer cells reminiscent of the anti-metastatic potential of nobiletin. Finally, nobiletin also blocked the NF-kB signalling pathway in a concentration-dependent manner.

CONCLUSIONS

Taken together, nobiletin may prove valuable as a promising drug candidate for pancreatic cancer treatment provided further studies are carried out on it, particularly toxicological studies.