Comprehensive analysis of FZD7 in immune infiltration and prognosis of pan-cancer and validation in hepatocellular carcinoma

Background: Frizzled 7, a G protein-coupled receptor, can regulate cell proliferation, migration, and tumorigenesis. The effect of FZD7 on prognosis and the immune microenvironment in pan-cancer remains elusive. Hence, we plan to provide insight into FZD7's role in pan-cancer. Methods: FZD7 expression was analyzed by integrating RNA sequencing data from TCGA and GEO databases. Furthermore, we elucidated the correlation between FZD7 and prognosis, mutation landscape, immune infiltration, and biological function by analyzing multiple databases in pan-cancer. A prognostic risk model was constructed based on the sequencing data of HCC in the TCGA database and its validity was verified in the GEO database. In addition, reverse transcription-polymerase chain reaction assays were performed to validate FZD7 expression in HCC tumor tissues. Results: Compared with adjacent noncancerous tissues, FZD7 was upregulated in several tumor tissues, especially HCC, and its elevated expression account for tumor progression and poor prognosis. Significant associations were found between FZD7 expression and TMB or MSI in several tumors. Immune infiltration analysis revealed a close link between FZD7 expression and the presence of myeloid-derived suppressor cells, T cell regulatory, as well as the cancer-associated fibroblasts. However, it negatively correlated with CD4 + Th1 cell and CD4 + Th2 infiltration. FZD7-related functional genes were successfully incorporated into the construction and validation of an HCC prognostic risk model. Conclusion: Our study indicated that FZD7 is involved in regulating the progression of several tumors and immune infiltration, while it can serve as an effective prognosis biomarker in pan-cancer, especially HCC. This could shed light on tumor therapy.