Gene Expression of HMG Proteins and miR-106a-5p in Low-and High-Grade Urothelial Papillary Carcinoma - A Comparative Analysis

Background: Urothelial carcinoma (UC) of the bladder exhibits low- and high-grade papillary forms with distinct prognoses. High mobility group proteins (HMGA1, HMGA2, HMGB1) and miR‑106a‑5p are involved in tumor progression, but their interplay in UC remains incompletely understood. The aim of this study was to compare the expression of these parameters in low- and high-grade papillary UC. Methods: Tissue samples from 80 patients (40 low-grade and 40 high-grade) undergoing transurethral resection or cystectomy were analyzed, with control samples consisting of tumor-adjacent tissues without histopathological alterations obtained from the same patients. HMGA1, HMGA2, and HMGB1 protein expression was assessed immunohistochemically. Gene expression was quantified by real-time PCR, and miR‑106a‑5p levels were measured by droplet digital PCR. Statistical analysis was conducted using Statistica 13.3, applying one-way ANOVA with Tukey’s post hoc test and correlation analysis, with p < 0.05 considered significant. Results: Expression of HMGA1 and HMGB1 was reduced in low-grade papillary urothelial carcinoma compared to control tissues, whereas both proteins were significantly increased in high-grade lesions. HMGA2 expression was minimal in low-grade tumors but partially restored in high-grade tumors. Analysis revealed the highest levels of miR-106a-5p in normal urothelium, slightly decreaseed in low-grade tumors, and significantly reduced in high-grade carcers. Conclusions: HMG proteins and miR‑106a‑5p demonstrate distinct expression patterns in low- versus high-grade papillary UC, which correlates with tumor aggressiveness. These molecules may serve as diagnostic and prognostic biomarkers and potential therapeutic targets. Further research is needed to clarify the underlying mechanisms and validate clinical applicability.