Abstract A124: Deciphering RIOK2 as a Potential Target for Hepatocellular Carcinoma via Enhancing Tumor Immune Infiltration and experimental in vitro validation

Abstract Background: RIOK2 is a principal transcription factor (TF) that is a key component of the pro-40S ribosomal complex in its final maturation step. But few studies have proved the rule of RIOK2 in carcinoma, especially in liver cancer. Furthermore, the relationship between RIOK2 and the prognostic potential and tumor-infiltrating immune cells of various cancers remains unclear. Methods: The clinical characteristics and mRNA expression level of RIOK2 were appraised among different databases. The relationship between RIOK2 and immunological infiltration of various types of cancer was determined via TIMER 2.0. Furthermore, RIOK2 inhibitors virtual screening was conducted from the 13633 natural compounds (L6020) and implemented secondary library construction according to the types of top results, then secondary virtual screening was conducted for 367 alkaloids. Finally, in vitro assays of RIOK2 ATPase activity assay, cell viability assays, and colony formation assay were performed to demonstrate the pharmacological potency of the screening RIOK2 inhibitors. Results: RIOK2 expression is higher in most types of tumors than in paracancerous tissues, including liver hepatocellular carcinoma (LIHC). Higher RIOK2 expression correlated with poorer OS, as well as a significant positive association between RIOK2 expression levels and infiltration levels of macrophages, neutrophils, and dendritic cells in LIHC patients. Moreover, we also found that K-252c and 2,3-Bis(3-indolylmethyl)indole are potent inhibitors of RIOK2. We have demonstrated in vitro that K-252c and 2,3-Bis(3-indolylmethyl)indole can inhibit the proliferation and clone formation of HepG2 cell lines by suppressing the expression of RIOK2. Conclusions: The findings showed that RIOK2 appears to be a promising prognostic biomarker for LIHC patients. Besides, K-252c and 2,3-Bis(3-indolylmethyl)indole may be effective therapeutic RIOK2 inhibitors for LIHC patients, providing a theoretical basis for the clinical treatment of LIHC. Citation Format: Jian He. Deciphering RIOK2 as a Potential Target for Hepatocellular Carcinoma via Enhancing Tumor Immune Infiltration and experimental in vitro validation [abstract]. In: Proceedings of the AACR IO Conference: Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2025 Feb 23-26; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2025;13(2 Suppl):Abstract nr A124.