Identification of CPLX1 expression as a potential prognostic marker in colorectal cancer.

[OBJECTIVES] CPLX1 is a member of the complexin/Synaphin family. Studies have shown that CPLX1 is involved in tumor progression. However, the biological mechanism by which CPLX1 is involved in colorectal cancer (CRC) is unclear.

[METHODS] TIMER and TCGA database provided difference expression of CPLX1 mRNA in pan-cancer and CRC. We collected 90 cases of CRC and adjacent normal tissues for immunohistochemistry (IHC) and investigated CPLX1 protein expression and its correlation with clinical information. Cox regression and Kaplan-Meier were conducted to determine prognostic value of CPLX1 expression. We utilized Spearman analysis to explore the association between CPLX1 and immune cell infiltration, immune checkpoints. We utilized GSEA to investigate the biological molecular function for CPLX1 in CRC.

[RESULTS] CPLX1 mRNA expression was elevated in several cancers, including CRC. Elevated CPLX1 protein expression was confirmed by IHC in CRC samples, and showed a positive association with T stage. The survival analysis demonstrated that CPLX1 overexpression was linked to a poorer overall survival (OS), disease-specific survival (DSS), and progress-free interval (PFI) for CRC. Time ROC analysis suggested that the survival rate of 1-year, 2-year and 3-year for OS, DSS, and PFI was above 0.5, suggesting a certain prognostic value in CRC. Cox regression considered CPLX1 expression as a good prognostic index for predicting OS, DSS, and PFI. Furthermore, CPLX1 expression was associated with immunity in CRC. Functional analysis showed that CPLX1 related genes had participation in Notch signaling pathway.

[CONCLUSIONS] CPLX1 was a latent prognostic and diagnostic marker for CRC and may also be a potential therapeutic target.