SR-BI expression regulates the gastric cancer tumor immune microenvironment and is associated with poor prognosis

Abstract

<b>Aim:</b> Scavenger receptor class B, type I (SR-BI) is an integral plasma membrane protein that has been reported to be overexpressed in various malignancies, such as renal cancer, breast cancer, and prostate cancer, and is an independent prognostic factor. However, the clinical value and expression of SR-BI in GC are unknown. Our research aimed to explore the role of SR-BI in combination with immune markers as a diagnostic and prognostic marker for gastric cancer (GC). <b>Methods:</b> GC tissues, paracancerous tissues, and clinicopathological data of 149 patients were collected. The expression level of SR-BI, Tumor-infiltrating lymphocytes (TILs), and PD-L1 were evaluated by immunohistochemistry (IHC). The associations of the SR-BI staining intensity with clinicopathological features and immune markers were determined by the chi-square test. Univariate and multivariate COX regression analyses were used to evaluate independent prognostic factors. Kaplan–Meier analyses were performed to plot the survival curve. <b>Results:</b> Our results indicated that SR-BI was expressed at higher levels in tumor tissues than in adjacent paracancerous tissues (<i>p</i> < 0.001), and patients with high levels of SR-BI expression had a worse prognosis. Univariate and multivariate analyses revealed that high SR-BI expression was an independent factor for poor prognosis. The chi-square test determined that the expression of SR-BI was negatively correlated with CD4+ T cells and CD8+ T cells (CD4+ T cells, <i>p</i> = 0.013; CD8+ T cells, <i>p</i> = 0.021), and positively correlated with PD-L1 (<i>p</i> = 0.022). Finally, survival analysis revealed that CD4+ T cells were associated with the prognosis of GC patients (<i>p</i> = 0.019), and the combined survival analysis of SR-BI and CD4+ T cells was also statistically significant (<i>p</i> = 0.030). <b>Conclusion:</b> SR-BI is highly expressed in GC tissue and associated with poor prognosis. Moreover, SR-BI can also regulate the GC tumor immune microenvironment.