Role of Kinetochore Scaffold 1 (KNL1) in Tumorigenesis and Tumor Immune Microenvironment in Pan-Cancer: Bioinformatics Analyses and Validation of Expression

PURPOSE: Kinetochore scaffold 1 (KNL1), a crucial protein during cell mitosis participating in cell division, was widely expressed in multiple kinds of cancers. However, the expression profile, the effect on cell biological function, tumor immune microenvironment, and predictive value of clinical prognosis in pan-cancer of KNL1 still require a comprehensive inquiry. METHODS: The mRNA and protein expression profile of KNL1 was validated in pan-cancer using different databases. Six algorithms were used to explore the correlation between KNL1 and immune infiltration and the relationship between KNL1 and tumor mutation burden (TMB), microsatellite instability (MSI), and TIDE score were calculated. The diagnostic and clinical prognostic predictive ability of KNL1 was assessed. Differentially expressed genes (DEGs) of KNL1 were screened out and function enrichment analyses were performed in pancreatic adenocarcinoma (PAAD), stomach adenocarcinoma (STAD), and bladder urothelial carcinoma (BLCA). Finally, 8 cases of pancreatic adenocarcinoma tissues and paired adjacent tissues were collected for immunohistochemical (IHC) staining and the histological score (H-score) was calculated. Real-time PCR was performed in gastric cancer and bladder cancer cell lines. RESULTS: KNL1 was abnormally upregulated in more than half of cancers across different databases. IHC and real-time PCR verified the up-regulated expression in cancer tissues in PAAD, gastric cancer, and BLCA. The satisfactory diagnostic value of KNL1 was indicated in 30 cancers and high KNL1 expression was associated with poorer overall survival (OS) in 12 cancers. The prognostic role of KNL1 as a predictive biomarker of PAAD was clarified. KNL1 played an active part in the cell cycle and cell proliferation. Moreover, KNL1 was likely to mold the Th2-dominant suppressive tumor immune microenvironment and was associated with TMB, MSI, and immune checkpoint-related genes in pan-cancer. CONCLUSION: Our study elucidated the anomalous expression of KNL1 and revealed that KNL1 was a promising prognostic biomarker in pan-cancer.