Elevated serum IL-22 levels correlate with chemoresistant condition of colorectal cancer

摘要

Colorectal cancer is one of the most common cancers with high mortality. The delivery of five-fluorouracil (5-FU) based chemotherapeutic agents following surgical resection is the standard treatment for advanced colorectal cancer. However, resistance to anti-tumor drugs and tumor recurrence remain a major obstacle in the treatment of this malignancy. Tumor cells are found to adopt multiple ways to resist chemotherapeutic agents, including decreased uptake or enhanced efflux of drugs, enhanced DNA repair ability, altered metabolism of drugs, alterations of drug targets and inhibition of apoptosis. In addition, secreted cytokines by lymphocytes are also considered to play an important role in drug resistance such as interleukin (IL)-6 and IL-8. IL-22, a member of IL-10 family of cytokines, is produced by immune cell subpopulations, including CD4+ T cells (Th1, Th17 and Th22 cells) and NK cells. The IL-22 receptor complex consists of two chains, IL-10R2 and IL-22R1, which are ubiquitously expressed in epithelial cells of various organs including the colon, kidney and liver. Previous studies have revealed that IL-22 is associated with tumorigenesis and tumor progression. To investigate the possible role of IL-22 in chemoresistance, we measured the serum level of IL-22 and correlated its level to chemosensitivity of colorectal cancer patients.