Polyphenol from millet bran increases the sensitivity of colorectal cancer cells to oxaliplatin by blocking the ganglioside GM3 catabolism
Colorectal cancer (CRC) is an aggressive malignancy with very limited therapeutic approaches. Drug resistance develops as a frequent characteristic in many patients with CRC, which leads to a decrease in the therapeutic efficacy of anticancer agents. Our previous evidences showed that bound polyphenol from millet bran (BPIS) possesses the potential of inhibiting cancer cell proliferation, and its main anticancer components are ferulic acid (FA) and p-coumaric acid (p-CA). In the present study, we found that BPIS significantly increases the sensitivity of human drug-resistant CRC cell line to oxaliplatin (OXA), a commonly used chemotherapy drug against CRC. Mechanistically, we indicated that BPIS significantly impairs the expression of a gene encoding multidrug resistance protein 1 (MDR1), a well-known permeability glycoprotein (P-gp), by preventing ganglioside GM3 catabolism. Neuraminidase 3 (NEU3) is a key enzyme catalyzing the conversion of ganglioside GM3 to ceramide trihexosides (Gb3), whose expression is increased in drug-resistant HCT-116/L cells. BPIS treatment increased GM3 level, but reduced Gb3 and P-gp levels by inhibiting NEU3 expression, which subsequently boosted the chemotherapy sensitivity of drug-resistant HCT-116/L cells to OXA. These findings reveal that BPIS increases the chemo-sensitivity by remodeling NEU3-mediated ganglioside GM3 catabolism, and it may be applied as a novel drug for facilitating the effectiveness of chemotherapeutic agents in CRC.