Antiproliferative effects of melatonin and menadione on colon tumoral cells

PICOTTO G; COLLIN A; LUQUE FESSIA A; TOLOSA DE TALAMONI N; KOHAN R

Jornada; Jornada de Investigación Científica de la FCM de la UNC; 2018

Colon cancer is one of the most important causes of death in entireworld. New pharmacological strategies are always needed, especially inresistant variants of this pathology. We have previously reported that oxidantdrugs such as menadione (MEN, vitamin K3) or D,L-buthionine-S,R-sulfoximine (BSO) increase tumour cellsensibility both invitro and invivo, due to their well known ability toreduce intracellular glutathione (GSH) content. Besides, melatonin (MEL), ahormone regulating circadian rhythms, inhibits the growth of tumor cells athigh doses.  The aim of this studywas to evaluate the effects of MEN and MEL on the proliferation of cultured coloncancer cells. Caco-2 cells (human colon adenocarcinoma) were treated with MEN, MEL, both orvehicle (ethanol). Cell proliferation was evaluated by crystal violet staining.Superoxide anion, GSH and nitric oxide (NO) levels were measured byspectrophotometry; nuclear morphology by Hoechst staining, and cell migrationby the wound healing assay. Statistically analyses:one way ANOVA and Bonferroni as a post-hoc test. MEN and MEL inhibited Caco-2 cellsgrowth and this effect was time and dose-dependent of treatment. Theantiproliferative effect began at 48 h being higher at 96 h. The concentration used for the next set of experiments was 20 µM and 750 µM for MEN and MEL, respectively. TotalGSH levels decreased at 6 h with MEN, which was blocked by MEL. Superoxideanion increased by MEN and drug combination. The NO production was increased byall treatments, resulting significantly higher with thecombined treatment. The combined treatment also causedmorphological nuclear changes, compatible with cell death. Cell migration wasdecreased by all treatments. In conclusion, MEL would increase theantiproliferative effect of MEN on Caco-2 cells mainly via nitrosative stress and arrest of cell migration. Thiscombination might be useful as a tool for intestinal cancer therapy.