To investigate the relationship between salt-inducible kinase 2 (SIK2) and lymph node metastasis in colorectal cancer patients complicated with chronic schistosomiasis. Tissue specimens were collected from 363 patients who were diagnosed as colorectal cancer by clinical and pathological examination in Wuhu Second People's Hospital from June 2015 to June 2020. Fifty-six patients were colorectal cancer complicated with schistosomiasis (CRC-S) and 307 patients were colorectal cancer not complicated with schistosomiasis (CRC-NS). The clinical and pathological data of the patients were analyzed to explore the relationship between chronic schistosomiasis and colorectal cancer. Immunohistochemistry and Western blotting were used to detect the distribution and expression of SIK2 in colorectal cancer specimens. The relationship between SIK2 and lymph node metastasis of CRC-S was analyzed. The rate of lymph node metastasis in CRC-S group was significantly higher than that in CRC-NS group (62.5% vs. 47.2%, <0.05). In CRC-S patients with lymph node metastasis, schistosome eggs were distributed mainly in tumor tissues (25/35, 71.4%), while in patients with CRC-S without lymph node metastasis, schistosome eggs were distributed mainly in paracancerous tissues (17/21, 81.0%) (14.243, <0.01). The SIK2 was mainly located in cytosol, and its expression in tumor tissues was higher than that in paracancerous tissues. Compared with CRC-NS patients, the expression of SIK2 in CRC-S patients was significantly increased; the expression of SIK2 in patients with lymph node metastasis was higher than that in patients without lymph node metastasis; and the expression of SIK2 in patients with schistosome eggs in cancer tissues was higher than that in patients with schistosome eggs in paracancerous tissues (all <0.01). Lymph node metastasis is more likely to be occurred in colorectal cancer patients with schistosomiasis, especially in those with schistosome eggs in tumor tissues. The expression of SIK2 may be correlated with chronic schistosomiasis, egg distribution and lymphatic metastasis.
Keywords: Colorectal cancer; Lymph node metastasis; Salt-inducible kinase 2; Schistosome egg; Schistosomiasis.