Anticancer Effects of Mahanimbine Alkaloid on the Human Bladder Cancer Cells Are Due to the Induction of G0/G1 Cell Cycle Arrest, Apoptosis and Autophagy

J BUON. Mar-Apr 2020;25(2):1166-1171.

Abstract

Purpose: The main purpose of the current research work was to investigate the anticancer effects of Mahanimbine alkaloid in human bladder cancer cells along with examining its effects on cellular apoptosis, cell cycle phase distribution, and cell autophagy.

Methods: Cell viability was examined by WST-1 cell viability assay. Mahanimbine-induced apoptosis was examined by fluorescent microscopy using acridine orange (AO)/ethidium bromide (EB) staining as well as using flow cytometry in combination with annexin-v/propidium iodide (PI) staining. Further, western blot assay was used to study the effects of Mahanimbine on apoptosis-related protein expressions including Bax and Bcl-2. Autophagy induction was evaluated by transmission electron microscopy (TEM) and western blot. Flow cytometry was used to study the effects on cell cycle.

Results: The results showed that Mahanimbine decreased the viability of the human bladder cancer cells and exhibited an IC50 of 32.5 µM. The test molecule also caused remarkable changes in the morphology of human bladder cancer cells and inhibited their colony forming potential. The AO/EB staining assay showed that Mahanimbine inhibits the viability of cancer cells via induction of apoptotic cell death which was associated with increase in Bax and decrease in Bcl-2 levels. The apoptotic cells increased from 5.2% in control to around 75% at 100 µM concentration. Mahanimbine also led to dose-dependent G0/G1 cell cycle arrest. Autophagic vacuoles appeared in the treated cells indicating autophagic induction by the test molecule. The Mahanimbine-triggered autophagy was also linked with increase in the expression of LC3II and decrease in p62 expression. However, no apparent effects were observed on the LC3 I expression.

Conclusion: Taken together, the results of this study indicate that Mahanimbine natural product has the potential to be developed as a promising anticancer agent against human bladder carcinoma but further studies are needed to this direction.