Silybin Showed Higher Cytotoxic, Antiproliferative, and Anti-Inflammatory Activities in the CaCo Cancer Cell Line while Retaining Viability and Proliferation in Normal Intestinal IPEC-1 Cells

The anticancer potential of silymarin is well known, including its anti-inflammatory as well as antiproliferative effect mediated by influencing the cell cycle, suppression of apoptosis, and inhibition of cell-survival kinases. However, less is known about silybin, the main component of the silymarin complex, where studies indicate its dual effect on the proliferation and immune response of various cell types in a dose-dependent manner. Moreover, there is a lack of studies comparing the effect of silybin on the same type of healthy and tumor cells, especially intestinal ones. Therefore, our study aimed to investigate the concentration-dependent effect of silybin on the normal intestinal porcine epithelial cell line-1 (IPEC-1) and the human epithelial colorectal adenocarcinoma cell line (CaCo-2). The metabolic viability, cell cycle, mitochondrial membrane potential, apoptosis, and the relative gene expression for pro- and anti-inflammatory cytokines were monitored in cells treated with silybin. Silybin stimulates metabolic viability as well as proliferation in IPEC-1 cells, protects the mitochondrial membrane, and thus exerts a cytoprotective effect, and has only a minimal effect on the gene expression of pro-inflammatory cytokines but significantly increases the expression of anti-inflammatory TGF-β. In contrast, it inhibits metabolic viability in tumor intestinal CaCo-2 cells, has an antiproliferative effect accompanied by increased apoptosis, and significantly reduces the expression of genes for pro-inflammatory interleukins as well as TGF-β. The antiproliferative and anti-inflammatory effect of silybin on tumor intestinal cells without a negative effect on healthy cells is a prerequisite for its potential use in the adjuvant therapy of colon cancer; however, further studies are necessary.