Construction and validation of prognostic model for colorectal mucinous adenocarcinoma patients and identification of a new prognosis related gene FAM174B.

Background: Mucinous adenocarcinoma (MAC) is a peculiar histological subtype of colorectal cancer (CRC) with distinct medical, disease-related, and genetic characteristics. The prognosis of MAC is generally poorer less favorable compared to non-specific adenocarcinoma (AC), but the prognostic indicator of MAC is rare. Therefore, this study aims to identify potential biomarkers and construct a prognostic model to better predict patient outcomes in MAC.

Methods: We conducted differential genes expression investigation, weighted gene co-expression network analysis (WGCNA), and least absolute shrinkage and selection operator (LASSO)-Cox regression model using RNA sequencing (RNA-seq) data from The Cancer Genome Atlas (TCGA) to pinpoint hub genes. Then, the hub genes were used to construct a prognostic model for MAC. Kaplan-Meier survival, receiver operating characteristic (ROC), and Cox regression analysis were used to assess the prognostic utility of the model. The potential biological function of the hub gene was examined using gene set enrichment analysis (GSEA).

Results: Four hub genes, FAM174B, CREB3L1, SPDEF, and RAP1GAP, were identified between MAC and AC by differential genes expression analysis, WGCNA, and LASSO regression analysis. The prognostic signature model was constructed based on these four hub genes, which could divide MAC into low- and high-risk groups. The overall survival (OS) was notably lower in the high-risk group compared to the low-risk group (P=0.007). The area under the curves (AUCs) for 1-, 3-, and 5-year OS were 0.61 [95% confidence interval (CI): 0.73-0.49], 0.69 (95% CI: 0.76-0.63), and 0.77 (95% CI: 0.83-0.71), respectively. We also found that FAM174B expression was closely related to the OS of MAC (P=0.02). Further, the expression of FAM174B was positively correlated with MAC's Mucin type O-glycan biosynthesis. Finally, it was indicated that FAM174B was positively correlated with the critical molecules of mucus formation, MUC5AC (P=0.004, r=0.33), MUC5B (P<0.001, r=0.43), and MUC2 (P<0.001, r=0.39).

Conclusions: We have developed and validated a four-gene prognostic model to predict the survival of MAC. Additionally, we found that FAM174B might correlate with mucin production in MAC.