Interleukin-17 promotes the development of cisplatin resistance in colorectal cancer

Cisplatin (DDP)-based anticancer therapy is an important chemotherapeutic strategy for the treatment of colorectal cancer. However, its beneficial effect is largely compromised by adverse reactions, and more importantly, by the development of drug resistance. Therefore, it is crucial to determine the potential mechanism underlying the development of DDP resistance in colorectal cancer. Interleukin-17 (IL-17) is a proinflammatory cytokine that has been found to serve an important role in the host defense during cancer development. It has been suggested that IL-17 is key to promoting the development of resistance to DDP in several major types of cancer. However, the role of IL-17 in DDP resistance in colorectal cancer has not been extensively investigated. In the present study, it was observed that IL-17 was significantly upregulated in colorectal tumor samples, compared with the adjacent tissues. Furthermore, IL-17 was found to promote the viability of HCT116 colorectal cells treated with DDP, whilst blocking IL-17 signaling leading to HCT116 cell apoptosis. IL-17 was also shown to regulate the expression of several apoptosis-related proteins, including phosphorylated-protein kinase B (p-Akt), apoptosis regulator BAX (Bax), apoptosis regulator Bcl-2 (Bcl-2) and serine/threonine-protein kinase mTOR (mTOR). These findings indicated that IL-17 facilitates the development of DDP resistance in colorectal cancer by inhibiting cancer cell apoptosis through targeting p-Akt, Bax, Bcl-2 and mTOR. Overall, the findings of the present study suggest that a combination of DDP and an IL-17 inhibitor may prove to be a highly efficient strategy for colorectal cancer treatment.