Homocysteine pre-treatment increases redox capacity in both endothelial and tumor cells.

Objective: We studied the modulatory effects of homocysteine pre-treatment on the disulfide reduction capacity of tumor and endothelial cells.

Methods: Human MDA-MB-231 breast carcinoma and bovine aorta endothelial cells were pre-treated for 1-24 hours with 0.5-5 mM homocysteine or homocysteine thiolactone. After washing to eliminate any rest of homocysteine or homocysteine thiolactone, cell redox capacity was determined by using a method for measuring disulfide reduction.

Results: Homocysteine pre-treatments for 1-4 hours at a concentration of 0.5-5 mM increase the disulfide reduction capacity of both tumor and endothelial cells. This effect cannot be fully mimicked by either cysteine or homocysteine thiolactone pre-treatments of tumor cells.

Discussion: Taken together, our data suggest that homocysteine can behave as an anti-oxidant agent by increasing the anti-oxidant capacity of tumor and endothelial cells.