Proteomic Analysis of HepG2 Cells Reveals FAT10 and BAG2 Signaling Pathways Affected by a Protease Inhibitor from Tinospora cordifolia Stem Extract Among the Different Plant and Microbial Samples Analyzed

INTRODUCTION: Dysregulation of proteolysis underlies diseases like cancer. Protease inhibitors (PIs) regulate many biological functions and hence they have potential anticancer properties. With this background, the current study was focused to identify a PI from natural sources such as plants and microbes against trypsin (a protease), which was assayed against casein, using a UV Spectrophotometer based methodology.
METHODS: PIs extracted from few plant and microbial samples were screened for their PI activity against trypsin. The PI from the most promising source in our study, T. cordifolia stem, was partially purified using Ammonium sulfate precipitation followed by dialysis. The PI activity of 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. LC-MS/MS based proteomic studies were performed on HepG2 cells to understand the signaling pathways affected by the PI in the liver cancer cell line.
RESULTS: Among the samples tested the PI from T. cordifolia stem extract had the highest inhibitory activity (72%) against trypsin along with cytotoxicity to HepG2 cells. After partial purification by 80% ammonium sulfate precipitation the PI had increased inhibitory activity (83%) against trypsin and enhanced cytotoxicity (47%) to HepG2 cells. Proteomic analysis of the PI treated HepG2 cells revealed that BAG2 and FAT10 signaling pathways were affected, which might be causing inhibition of cancer cell proliferation.
DISCUSSION AND CONCLUSION: PI from T. cordifolia stem has promising anticancer potential and hence can be taken up for further purification and characterization studies towards cancer drug development.