Comprehensive Analysis of the Prognostic Value and Immune Infiltration of Calpains in Pancreatic Cancer

Abstract Background: Calpains (CAPNs) are intracellular calcium-activated neutral cysteine proteinases that are involved in cancer initiation, progression, and metastasis; however, their role in pancreatic cancer (PC) remains unclear. Methods: We combined data from various mainstream databases (i.e., Oncomine, GEPIA, Kaplan-Meier plotter, cBioPortal, STRING, GeneMANIA, and ssGSEA) and investigated the role of CAPNs in the prognosis of PC and immune cell infiltration.Results: Our results showed that CAPN1, 2, 4, 5, 6, 8, 9, 10, and 12 were highly expressed in PC. The expression levels of CAPN1, 5, 8, and 12 were positively correlated with the individual cancer stages. Moreover, the expression levels of CAPN1, 2, 5, and 8 were negatively correlated with the overall survival (OS) and recurrence-free survival (RFS); whereas that of CAPN10 was positively correlated with OS and RFS. We found that CAPN1, 2, 5, and 8 were correlated with tumour-infiltrating T follicular helper cells and CAPN10 with tumour-infiltrating T helper 2 cells. Functional enrichment analysis showed that the differentially expressed CAPNs (CAPN1, 2, 5, 8, and 10) are involved in axonogenesis, cell-substrate adhesion, immune response-activating cell surface receptor signalling pathway, and cell junction organisation in PC.Conclusions: These results suggested that CAPN1, 2, 5, 8, and 10 could be used as prognostic biomarkers in PC and can assist in improving individualised treatment strategies.