Data Sheet 1_Clinicopathological data and the role of miRNA expression in patients with pheochromocytomas/paragangliomas.docx

BackgroundPheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors with variable behavior and metastatic potential. Reliable prognostic biomarkers are needed to improve risk stratification and long-term management. Emerging data suggest a role for microRNAs (miRNAs) and immune checkpoint pathways (or inhibitors) in tumor aggressiveness.
ObjectiveTo evaluate the expression of five candidate miRNAs (miR-15a, miR-16, miR-101, miR-183, and miR-483-5p) and programmed death ligand-1 (PD-L1) in PPGL tissues, and assess their associations with clinicopathological features, genetic status and outcomes.
MethodsA retrospective cohort of 130 patients with PPGLs was analyzed, including 53 PPGL tumor and 20 normal adrenal medulla tissues (controls). MiRNA expression was assessed by RT-qPCR in 53 formalin-fixed paraffin-embedded samples (FFPE). PD-L1 and microsatellite instability (MSI) were evaluated by immunohistochemistry in FFPE samples. Associations with tumor type and size, functionality, Ki-67 index, grading scores (PASS, GAPP), metastatic status, localization, and genotype were examined.
ResultsOverall, 21.5% (28/130) of patients developed metastases during a median period of follow-up of 45 months and 35 out of the 61 tested (57.4%), harbored pathogenic germline mutations. In tumor samples (n=53), PD-L1 expression was observed in 18.9% (10/53) whereas no MSI expression was detected. MiR-483-5p was the most consistently upregulated marker in biochemically negative and in high–Ki-67 tumors along with significant up regulation in metastatic PPGL, supporting its role in cellular proliferation and metastatic potential. MiR-183 and miR-101 were overexpressed in pheochromocytomas (PHEOs) with high PASS and Ki-67 indices, while miR-15a and miR-16 displayed higher levels in non-metastatic tumors.
ConclusionMiR-483-5p emerges as a promising biomarker of aggressive PPGL behavior, while other miRNAs reflect distinct biological behaviors. PD-L1 expression in a subset of cases highlights immune checkpoint inhibition as a potential therapeutic strategy. Prospective validation is warranted.