CONICET | Buscador de Institutos y Recursos Humanos

Colon cancer is one of the mostimportant causes of death in entire world. New pharmacological strategies arealways needed, especially in resistant variants of this pathology. We havepreviously reported that oxidant drugs such as menadione (MEN) or D,L-buthionine-S,R-sulfoximine(BSO) increase tumour cell sensibility, due to their well known ability toreduce glutathione (GSH) content. Besides, melatonin (MEL), a hormoneregulating circadian rhythms, has antioxidant and antiapoptotic properties atlow concentrations, while at high doses it has been shown to inhibit the growthof tumor cells. The aim of this study was to evaluate the the effects of MENand MEL on the proliferation of colon cancer cells. Caco-2 cells (human colon adenocarcinoma) were treated with MEN, MEL, both or vehicle(ethanol). Cell proliferation was evaluated by crystal violet staining. Superoxideanion, glutathione levels (GSH) and nitric oxide (NO) levels were measured byspectrophotometry. Nuclearmorphology was evaluated by Hoechst staining and cell migration by the woundhealing assay. Statistically analyses: one way ANOVAand Bonferroni as a post-hoc test. MEN and MEL inhibited Caco-2 growth and thiseffect was time and dose-dependent. The antiproliferative effect began at 48 hbeing higher at 96 h. The concentration used for the next set of experiments was 20 µM and 750 µM for MENand MEL, respectively. Total GSH levels decreased at 6 h with MEN, which was blocked by MEL. Superoxideanion increased by MEN, and the NO production was increased by MEN, MEL and MEN+MEL.The combined treatment caused morphological nuclear changes, compatible withcell death. Cell migration was decreased by all treatments. In conclusion, MEL enhancesthe antiproliferative effect of MEN on Caco-2 cells mainly via nitrosative stress and arrest of cell migration. This combination might be useful asa tool for intestinal cancer therapy.