Deciphering ERR Family Genes as Prognostic and Immunological Biomarkers through Pan-Cancer Analysis with Validation in Gallbladder Cancer

Wanwan Gong ^1,2 Sijia Wen ^1,2 Yu Chen ³ Fan Wu ^1,2 Mengmeng Yang ⁴ Ping Sun ¹ Xingmei Guo ¹ Meiqin Li ¹ Daozhen Chen ^3,5 Hui Zhao ¹ Lei Wang ^1,3,5*

• ¹ Jiangnan University Medical Center (JUMC）, Wuxi, China
• ² Wuxi Medical College, Jiangnan University, Wuxi, Jiangsu Province, China
• ³ Research Institute for Reproductive Health and Genetic Diseases, Wuxi Maternal and Child Health Hospital, Wuxi School of Medicine, Jiangnan University,, Wuxi, Liaoning Province, China
• ⁴ Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases,, Wuxi, Liaoning Province, China
• ⁵ Research Institute for Reproductive Health and Genetic Diseases, The Affiliated Wuxi Maternity and Child Health Care Hospital of Nanjing Medical University,, Wuxi, Liaoning Province, China

The estrogen-related receptor family genes (ERRs), including ESRRA, ESRRB, and ESRRG, have been implicated in a few tumors, exhibiting distinct roles through diverse mechanisms. The purpose of our research is to explore the commonalities and underlying mechanism of ERRs in malignancies from a pan-cancer perspective and to validate the role and mechanisms of ESRRG in gallbladder cancer (GBC) through histological and cellular experiments, thereby corroborating the findings of our pan-cancer analysis. Compared to adjacent normal tissues, ESRRA is overexpressed in most tumors, ESRRB is generally underexpressed, and ESRRG exhibits significant expression alterations across various tumors. All three ERRs demonstrate significant prognostic value across different cancers. Notably, the strong associations of ERRs with key immunological features-stromal scores, immune cell infiltration, microsatellite instability (MSI), and tumor mutational burden (TMB)-suggest their involvement in immune evasion and their potential utility in guiding immunotherapy strategies. All three ERRs display a positive correlation with advanced tumor stages in cholangiocarcinoma (CHOL). Specifically, in CHOL, ESRRG expression is closely associated with lymphatic metastasis, poorer overall survival, reduced immune infiltration, elevated PD-L1 expression, epithelial-mesenchymal transition (EMT), and DNA damage response. In GBC tissues, we subsequently confirmed that ESRRG expression positively correlates with pathological staging and PD-L1 expression, while negatively correlating with prognosis and CD8+ T cell infiltration. Knockdown of ESRRG in gallbladder cancer cells results in decreased proliferation, migration, and invasion. Moreover, the expression of PD-L1, PCNA, MSH2, BRCA1, MMP2, and VIMENTIN decreased with ESRRG knockdown.