Proteomic Analysis of HepG2 Cells Reveals FAT10 and BAG2 Signaling Pathways Affected by a Protease Inhibitor from (Willd.) Hook. f. and Thoms Stem. Extract Among the Different Plant and Microbial Samples Analyzed.

Objectives: Dysregulation of proteolysis underlies diseases like cancer. Protease inhibitors (PIs) regulate many biological functions and hence have potential anticancer properties. With this background, the current study aimed to identify the PI from natural sources such as plants and microbes against trypsin (a protease), which was assayed against casein, using an ultraviolet spectrophotometer-based methodology.

Materials And Methods: PI extracted from a few plants and microbial samples were screened for their PI activity against trypsin. The PI from the most promising source in our study, Tinospora cordifolia (Willd.) Hook. f. and Thoms. stem, was partially purified using ammonium sulfate precipitation followed by dialysis. The PI activity of the partially purified inhibitor was analyzed against chymotrypsin and collagenase enzymes, and the cytotoxic effect of the PI was checked on HepG2 (liver carcinoma) cells by MTT- [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide]- assay. Liquid Chromatograography Mass Spectrometry -based proteomic studies were performed on HepG2 cells to understand the signaling pathways affected by the PIs in the liver cancer cell line.

Results: Among the samples tested the PIs from stem extract had the highest inhibitory activity (72.0%) against trypsin along with cytotoxicity to HepG2 cells. After partial purification by 80.0% ammonium sulfate precipitation, PI had increased inhibitory activity (83.0%) against trypsin and enhanced cytotoxicity (47.0%) to HepG2 cells. Proteomic analysis of the PI-treated HepG2 cells revealed that BAG2 and FAT10 signaling pathways were affected, which may have caused the inhibition of cancer cell proliferation.

Conclusion: PI from stem has promising anticancer potential and hence can be used for further purification and characterization studies toward cancer drug development.