An integrated analysis identified mitochondrial ribosomal protein MRPL3 as a potential prognostic biomarker and therapeutic target in pancreatic cancer.

Mitochondria play a crucial role in tumor metabolism. Mitochondrial ribosomal protein L3 (MRPL3) is a core component of the mitochondrial ribosome. However, its role in pancreatic cancer (PC) remains unclear. We investigated the biological functions and underlying mechanisms of MRPL3 in PC. The expression of MRPL3 was analyzed using public databases. Prognostic significance was evaluated using Kaplan-Meier survival analysis and univariate/multivariate Cox regression. Functional enrichment analysis was performed to identify MRPL3-associated signaling pathways. In addition, immune cell infiltration and tumor mutational burden (TMB) analyses were conducted to explore the relationship between MRPL3 expression and the tumor microenvironment. Tumor immune dysfunction and exclusion (TIDE) scores and drug sensitivity analyses were used to assess the therapeutic implications of MRPL3. Western blotting and immunohistochemistry (IHC) were performed to validate MRPL3 expression and evaluate their prognostic significance in clinical PC samples. <i>In vitro</i> experiments were performed to determine the effects of MRPL3 silencing on PC cell behavior. MRPL3 expression was notably increased in PC and associated with an unfavorable prognosis in public cohorts. Functional enrichment and immune infiltration analyses revealed that high MRPL3 expression was associated with damage to the G2/M DNA checkpoint, increased Th2 cell infiltration, and reduced natural killer (NK) cell activity. Furthermore, high MRPL3 expression corresponded to lower immunotherapy sensitivity and higher chemotherapy sensitivity. The IHC analysis confirmed that high MRPL3 expression is associated with significantly shorter overall survival in PC (hazard ratio [HR] = 2.13, 95% confidence interval [CI] = 1.35-3.34, <i>p</i> = 0.001). <i>In vitro</i> experiments demonstrated that MRPL3 knockout significantly suppressed PC proliferation, migration, and invasion. MRPL3 promotes PC progression, immune evasion, and therapeutic resistance, contributing to an unfavorable prognosis. It may serve as a promising biomarker and potential target for individualized treatment strategies.