A histology-based four protein array for postoperative outcome prediction in clear cell renal cell carcinoma

Renal cell carcinoma is the 9th and the 14th most common cancer in men and women worldwide, respectively. Clear cell histology is the most common subtype of renal cell carcinoma, which accounts for about 70-75% of all cases. The pathogenesis of renal cell carcinoma is not well clarified and various factors are reported to be associated with kidney cancer. Identifying novel clinical and pathological features associated with the diagnosis, prognosis and targeted therapies of ccRCC patients is an essential task. Interleukin-22 (IL-22) belongs to the IL-10 family of cytokine and is produced by several subsets of lymphocytes. IL-22 plays an important role in sustaining the integrity of several organs and it prevents injury due to invading pathogens and the subsequent inflammatory response. Moreover, IL-22 has been reported to be associated with cancers in several organs. IL-22 mediates its biological effect by binding to the heterodimeric transmembrane complex of IL-22RA1 and IL-10R2. In the present study, the expression pattern of IL-22 and IL-22RA1 and their association with the survival of ccRCC patients from The Cancer Genome Atlas were analyzed. Then 60 tumor samples from non-metastatic ccRCC patients were selected for IL-22, IL-22RA1, IL-22BP, Ki-67, Caspase-3 immunohistochemical staining. Afterwards, staining evaluation was performed, and the patients’ clinicopathologiccal characteristics were analyzed and the correlations between immunohistochemical variables and patients’ outcome were assessed. From the TCGA analysis results, patients without alterations in IL-22 or IL-22RA1 had a significantly good overall survival and disease-free survival compared to patients with alteration in IL-22 or IL-22RA1. Immunohistochemical staining detected IL-22, IL-22RA1, Ki-67, and caspase-3 positive tumor cells, but no IL-22BP positive cell was detected. Statistical analysis showed that IL-22 expression was correlated with Fuhrman grade, primary T stage, relapse and vital status of ccRCC patients. And IL-22RA1 expression was associated with Fuhrman grade, relapse, and vital status of ccRCC patients. Moreover, Kaplan-Meier analysis revealed that ccRCC patients with high expression of IL-22 had a poor overall survival and disease-free survival compared to patients with low expression of IL-22. This was true also for IL-22RA1 and Ki-67. However, ccRCC patients with high expression of caspase-3 only showed a significantly poor disease-free survival, but not overall survival. In addition, multivariable Cox proportional hazards regression model showed that tumor stage, presence of necrosis in tumor, and IL-22RA1 probably are independent predictors for overall survival of ccRCC patients, and Fuhrman grade, tumor stage, presence of venous thrombus and IL-22RA1 are independent predictors of disease-free survival of ccRCC patients. Several conclusions can be drawn: the IL-22-IL-22RA1 axis is correlated with several clinicopathological characteristics such as Fuhrman grade, primary T stage, relapse and vital status of ccRCC patients; ccRCC patients with lower expression level of IL-22, IL-22RA1, Ki-67 tend to have a longer survival time; IL-22RA1 but not IL-22, is an independent predictive factor for prognosis of ccRCC patients.