Causal relationship between ferroptosis-related gene HSPA5 and hepatocellular carcinoma: study based on mendelian randomization and mediation analysis.

Objectives: To explore the causal relationship between ferroptosis-related gene heat shock protein A5 (HSPA5) and hepatocellular carcinoma (HCC).

Methods: A two-sample Mendelian randomization (MR) design was employed to evaluate the causal relationships among HSPA5, regulatory T cells (Tregs), and liver cancer. Single nucleotide polymorphisms (SNPs) associated with HSPA5, HCC and Tregs were selected as instrumental variables through publicly available genome-wide association studies (GWAS) databases. MR analysis was used to assess the direct effect of HSPA5 on HCC, followed by two-step MR to analyze the potential mediating role of Tregs. Reverse MR analysis was conducted with liver cancer as the exposure and HSPA5 as the outcome. Inverse variance weighting (IVW) was the primary method for testing causal associations in all MR analyses. Robustness of the results was confirmed through MR Egger, weighted median, weighted mode, and simple mode methods. Heterogeneity of instrumental variables was evaluated using Cochrane's Q statistic, while pleiotropy was tested by MR-Egger intercept and MR-PRESSO, with leave-one-out sensitivity analysis performed for robustness. Data from The Cancer Genome Atlas (TCGA) and Human Protein Atlas (HPA) were utilized to verify the expression levels of HSPA5 in liver cancer tissues and its correlation with Tregs to reveal the interaction mechanisms between HSPA5 and Tregs in HCC progression and their relationship with patient prognosis.

Results: MR analysis showed a positive correlation between elevated HSPA5 expression and liver cancer risk (all P<0.01), while reverse MR analysis found no statistically significant association between liver cancer and HSPA5 (P>0.05). HSPA5 expression was significantly correlated with Tregs function (all P<0.05), and the enrichment of Tregs in the liver cancer microenvironment was positively associated with liver cancer progression (all P<0.05). Mediation analysis indicated that Tregs accounted for 5.00% and 7.45% of the mediation effect between HSPA5 and liver cancer. TCGA and HPA database analysis revealed that both HSPA5 mRNA and protein expression levels were higher in liver cancer tissues compared to normal tissues, and high HSPA5 expression was significantly associated with poor patient prognosis. Immune infiltration analysis confirmed a significant positive correlation between HSPA5 and Tregs, with high Tregs infiltration closely related to HCC progression.

Conclusions: Elevated HSPA5 expression is significantly associated with HCC development and poor prognosis. HSPA5 may promote HCC progression by regulating the function of Tregs in the tumor microenvironment.