Toxigenomic Evaluation of Diallyl Disulfide Effects and Its Association with the Chemotherapeutic Agent 5-Fluorouracil in Colorectal Cancer Cell Lines

<b>Background/Objectives</b>: Colorectal cancer (CRC) is among the most prevalent malignant neoplasms globally. Chemotherapeutic treatment strategies have demonstrated minimal improvement over the past decade. Combination therapies, including those with nutraceuticals, are currently being investigated as promising alternatives to enhance therapeutic efficacy. The organosulfur garlic extract diallyl disulfide (DADS) has demonstrated anti-tumoral activity in several types of cancer. This study aimed to investigate the effects of DADS and 5-fluorouracil (5-FU), both individually and in combination, on the human CRC cell lines Caco-2 and HT-29. <b>Methods</b>: Caco-2, HT-29, and non-tumoral human umbilical vein endothelial cells (HUVEC) were exposed to DADS (25-600 µM) and 5-FU (5-100 µM), either individually or in simultaneous combination (DADS 100 µM + 5-FU 100 µM), for 24 h. Cytotoxicity was evaluated in all three cell lines. In addition, the effects of these treatments on oxidative stress, cell migration, genotoxicity, cell death, global DNA methylation, and gene-nutraceutical interactions were assessed in both tumor cell lines. <b>Results</b>: DADS demonstrated cytotoxic effects at high concentrations in Caco-2, HT-29, and HUVECs and induced DNA damage in both colorectal cancer cell lines. The combination of DADS and 5-FU significantly promoted apoptotic cell death, increased genotoxicity, elevated global DNA methylation, and inhibited cell migration, with these effects being particularly pronounced in HT-29 cells. <b>Conclusions</b>: We provide evidence that DADS combined with 5-FU is potentially useful in the therapy of CRC. However the combination of nutraceuticals and chemotherapy must consider the distinct molecular and phenotypic characteristics of each tumor cell line.