SLITRK2 as a Prognostic and Immunological Biomarker in Gastric Cancer

Background SLIT and NTRK-like protein 2 (SLITRK2) encodes a transmembrane protein that regulates neurite outgrowth and promote synaptogenesis. Some studies have demonstrated that SLITRK2 overexpressed in glioma. But the expression pattern, prognostic value, and immunologic function of SLITRK2 in tumors remains unknown. Methods The expression pattern of SLITRK2 among pan-cancers were examined through different databases, including the Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx). We analyzed the SLITRK2 expression in different stages of cancers. The relationship between SLITRK2 expression and clinical outcomes was conducted by Kaplan-Meier method. Moreover, the correlations among SLITRK2 expression, immune cell infiltration, immunomodulatory related genes, tumor mutation burden (TMB), microsatellite instability (MSI) were evaluated as well. The relationship between SLITRK2 expression and crucial genes mutations was also illustrated. By using tissue multi-array (TMA), the expression of SLITRK2 in 89 paired gastric cancer tissues was investigated. Results Our study indicated that SLITRK2 expression varied across cancers. Elevated SLITRK2 expression was positively related to advanced tumor stage, poor overall survival(OS) and reduced disease-free survival (DFS). It also verified that SLITRK2 expression level was correlated with immune cell infiltration, expression of immunomodulators, TMB, MSI in certain cancer types. In stomach adenocarcinoma (STAD), SLITRK2 expression and clinicopathological features revealed that high expressing level of SLITRK2 associated with poorer outcomes. Importantly, based on tissue TMA data, SLITRK2 expression level was positively associated with differentiation, lymph node metastasis, AJCC stage, TNM stage, and poor survival outcome in GC patients. Conclusion Our findings provided that SLITRK2 may function as a potential biomarker and oncogene in pan-cancer. In addition, SLITRK2 was correlated with immune cell infiltration in pan-cancer, providing a potential drug target, especially in STAD.