Exploring the effect of capsaicin on gene expression and chemotherapy sensitization in gastric cancer cells

Purpose: Capsaicin has previously been demonstrated to exhibit anti-tumor effect in various cancer type. However, the effect of capsaicin on gene expression and its potential mechanism on chemotherapy sensitization were still uncertain. Method: Human AGS gastric cancer cell line was treated with different concentrations of capsaicin, 5-fluorouracil and oxaliplatin. Cell viability was assessed using cell viability assay. High throughput RNA sequencing was used to screen differentially expressed genes triggered by capsaicin in AGS cells. qPCR and Western blotting were used to detect the expression of mRNAs and proteins induced by capsaicin. Result: Capsaicin could significantly inhibit cell viability at a dose-depend manner in AGS gastric cancer cell line. Through high-throughput RNA sequencing, genes regulating DNA repair, DNA replication and chromosome assemble pathways were analyzed to be down-regulated by capsaicin. qPCR and western blot assay demonstrated that capsaicin could inhibit expression of the key enzymes (FEN1, LIG1 and PARP1) which play critical roles in DNA damage response and chemotherapy resistance. In vitro assay demonstrated that capsaicin could significantly induce chemo-sensitivity of 5-FU and Oxaliplatin at low dose. Conclusion: Capsaicin could inhibit DNA repair pathway, which might contribute to cell growth inhibition and improvement of chemotherapy sensitization. These results revealed a novel function of capsaicin in DNA damage repair and provided new potential targets in cancer therapy.