Contribution of RalA and RalB in colorectal cancer progression and survival

Background: RalA and RalB, members of the Ras superfamily, have been implicated in tumor growth, invasion, and metastasis across multiple cancers. However, their protein-level expression and clinicopathological relevance in colorectal cancer (CRC), particularly in South Asian populations, remain insufficiently characterized. This study aimed to evaluate RalA and RalB protein expression in CRC tumor versus matched normal tissues and to determine their associations with clinicopathological features and patient survival. Methods: A total of 123 formalin-fixed paraffin-embedded (FFPE) CRC tumor samples and 43 matched normal tissues were obtained from the Aga Khan University Hospital, Karachi, following ethics approval. Tissue microarrays were constructed, and immunohistochemistry for RalA and RalB was performed using standard protocols. Expression was quantified using the Immunoreactivity Score (IRS; range 0-9). Patients were stratified into high- and low-expression groups based on median IRS. Correlations with clinicopathological parameters were assessed using Spearman's rho. Kaplan-Meier curves and log-rank tests evaluated associations with overall survival (OS). Results: RalA expression was increased in tumor samples albeit not significantly (median IRS 6 vs. 4; p = 0.499). RalB was significantly higher in tumor tissue than in normal (median IRS 4 vs. 2; p = 0.028). High RalB expression was strongly associated with reduced OS (decline from ~95% to ~50% over 150 months; log-rank p = 0.05), whereas RalA expression showed no significant prognostic effect (p =0.428). Both proteins demonstrated significant negative correlations with tumor grade (RalA ρ = -0.316; RalB ρ = -0.310; p = 0.002), but no associations with disease stage, perinuclear invasion and lymph vascular invasion. Conclusion: RalB, more than RalA, is significantly upregulated in colorectal tumors and serves as a strong negative prognostic marker for overall survival. The inverse correlation of Ral proteins with tumor grade warrants further investigation. However, these findings support RalB as a potential biomarker for risk stratification and as a candidate for therapeutic targeting in CRC.