Supra-physiological concentration of glyoxylate inhibits proliferation of human colon cancer cells through oxidative stress.

Aims: The cytotoxic response of an intermediate metabolite glyoxylate (Glx) on colon carcinoma has been evaluated in vitro.

Main Methods: The anti-proliferative effect of Glx was assessed on HT-29 and HCT-116 cells by performing MTT assay as well as beta-hexosaminidase assay. Evaluation of apoptotic event of Glx treated cells was measured by flow cytometry using annexin-V/PI staining. The mitochondrial membrane potential and level of ROS were estimated using DiOC(3)/CCCP and DCFH-DA method, respectively. The assessment of catalase, LDH and IDH were performed.

Key Findings: The results of MTT assay indicated that treatment with Glx significantly inhibited the proliferation of HT-29 and HCT-116 cells. Beta-hexosaminidase assay also confirmed the inhibition of cellular viability. The dose-dependent Glx treatment indicated lowering the colony forming ability of HT-29 and HCT-116 cells. Flow cytometric data demonstrated the significant increment of late apoptotic event after Glx treatment. In addition, substantial LDH activity was noticed in both the colon cancer cells whereas the IDH activity was unaltered after extra-cellular addition of Glx. Further, dissipation of mitochondrial membrane potential and subsequently elevated ROS generation was also detected in the Glx treated colon cancer cells. However, gradual elevation of catalase activities indicated that Glx treatment on colon cancer cells exhibit oxidative stress.

Significance: This study depicts that supra-physiological concentration of Glx inhibits the proliferation of colon cancer cells due to oxidative stress.