Background: There are few studies on the inhibition effects of soy peptides on hepatocarcinoma
cells. Further insight into the underlying relationship of soybean peptides and hepatocarcinoma
needs to be addressed. Therefore, it is worthwhile investigating the possible mechanisms of
soybean peptides, especially the hepatocarcinoma effects.
Objective: In this study, we try to figure out the molecular mechanisms of soy peptides QRPR and
HCQRPQ on HepG2 cells.
Methods: First, we use the MTS assay to determine the effect on cell proliferation of soy peptides
QRPR and HCQRPQ on HepG2 cells. Subsequently, we examine the apoptosis of HepG2 cells via
transmission microscopy and Annexin V-FITC/PI assay induced by soybean peptides. The cell
cycle distribution is analyzed using flow cytometry. Finally, we analyze the effects of soy peptides
on the TNF-α expression via ELISA assays and the caspase-8 and caspase-3 expression level via
western blot and the quantitative real-time PCR.
Results: Soy peptides QRPR used in combination with HCQRPQ can inhibit the growth of HepG2
cells, and the cytotoxicity is low. The transmission microscopy and Annexin V-FITC/PI assay reveal
that these two soy peptides induce apoptosis in HepG2 cells. Soy peptide-treated HepG2 cells
accumulate in the G1 phase. ELISA shows that soy peptides reduce the secretion of TNF-α. The
western blot and the quantitative real-time PCR results show that these soy peptides increased the
expression of caspase-8 and caspase-3.
Conclusion: We speculate that soy peptides QRPR used in combination with HCQRPQ can inhibit
the growth of HepG2 cells through the TNF-α mediated pathway.