Correlation between SMADs and Colorectal Cancer Expression, Prognosis, and Immune Infiltrates

Background: In current years, the incidence and mortality of colorectal cancer (CRC) are increasing, and the 5-year survival rate of advanced metastatic CRC is poor. The Small mothers against decapentaplegic (SMAD) superfamily is an intracellular signal transduction protein associated with the development and prognosis of a variety of tumors. At present, no study has systematically analyzed the relationship between SMADs and CRC.Methods: Here, R3.6.3 was used to analyze the expression of SMADs in pan-cancer and CRC. Protein expression of SMADs were analyzed by HPA. GEPIA was used to evaluate the correlation between SMADs and tumor stage in CRC. The effect of R language and GEPIA on prognosis was analyzed. Mutation rates of SMADs in CRC were determined by c-BioPortal and potentially related genes were predicted using GeneMANIA. R analysis was used for correlation with immune cell infiltration in CRC.Results: Both SMAD1 and SMAD2 were found to be weak expression in CRC and correlated with immune invasion level. SMAD1 was correlated with patient prognosis, and SMAD2 was correlated with tumor stage. SMAD3, SMAD4 and SMAD7 were all low expressed in CRC and associated with a variety of immune cells. SMAD3 and SMAD4 proteins were also low expressed, and SMAD4 had the highest mutation rate. SMAD5 and SMAD6 were overexpressed in CRC, and SMAD6 was also associated with patient OS and CD8+ T cells, macrophages and neutrophils. Conclusions: Our results reveal innovative and strong evidence that SMADs can be used as biomarkers for the treatment and prognosis of CRC.