The mortality of colorectal cancer is expected to increase in some countries including the United States, which necessitates the identification of new molecules that help in prognosis assessment and survival improvement. In this brief report, we evaluated the potential of interleukin-34 (IL-34) as a prognostic factor in colorectal cancer. IL-34 was reported for the first time in 2008 as a novel cytokine that controls the biology of the myeloid cell lineage. Accumulating evidence suggests important roles for IL-34 in modifying the tumor microenvironment and enhancing therapeutic resistance of cancer. In this study, we found that IL-34 expression was detectable in various colorectal cancer cell lines in addition to primary cancer tissues from a cohort of Japanese colorectal cancer patients, ranging from high to absent. A Kaplan-Meier analysis showed that high expression of IL-34 correlated with poor survival of colorectal cancer patients. Importantly, in both univariate and multivariate analysis, high IL-34 expression correlated with unfavorable prognosis. A similar relationship between IL-34 expression and the poorer prognosis was also observed in a cohort of colorectal cancer patients registered at The Cancer Genome Atlas. Together, these findings indicate a potential role for IL-34 as a prognostic factor in colorectal cancer.
Keywords: Colorectal cancer; immunohistochemistry; in silico; interleukin-34; prognosis.