SSRP1 Is a Prognostic Biomarker Correlated with CD8+ T Cell Infiltration in Hepatocellular Carcinoma (HCC)

Background. Hepatocellular carcinoma (HCC), one of the most common primary malignancies, is theoretically an epitope candidate for immune checkpoint inhibitors, and therefore, the identification of HCC biomarkers is important. Structure‐specific recognition protein 1 (SSRP1) is involved in almost all chromatin‐related processes, including DNA replication, repair, and transcription. However, its role in HCC remains to be elucidated. Methods. This study investigated the expression of SSRP1 in HCCDB, Oncomine, HPA, and other databases. The prognostic value of SSRP1 in HCC and its relationship with clinical characteristics were then explored using Kaplan‐Meier plotter. At the same time, SSRP1 coexpression genes were explored and functionally annotated in the LinkedOmics database. Finally, the correlation between the SSRP1 expression and HCC immune cell infiltration was explored in TIMER and online single‐cell sequencing database. Results. Significantly elevated transcriptional and proteomic SSRP1 expressions were found in HCC. Increased SSRP1 mRNA expression was significantly correlated with relevant clinicopathological parameters such as immune cells. Notably, the SSRP1 expression was positively correlated with the infiltration levels of Treg and CD8+ T cells, especially exhausted CD8+ T cells. Interestingly, the SSRP1 expression was higher in both tumor Treg and exhausted CD8+ T cells than in adjacent tissues. Conclusion. SSRP1, as a new prognostic marker for HCC, promotes HCC development by influencing the infiltration of depleted CD8+ T cells and may influence the effect of immunotherapy.