Hypermethylation-mediated silencing of RASD1 drives multiple myeloma pathogenesis.

BACKGROUND

The role of Ras-related dexamethasone-induced 1 (RASD1) in multiple myeloma (MM) pathogenesis remains unclear. This study investigated the expression profile, clinical significance, and epigenetic regulation of RASD1 in MM.

METHODS

Bone marrow samples were collected from 26 newly diagnosed patients with MM and 8 healthy controls. RASD1 messenger RNA (mRNA) and protein expression were analyzed using reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry, respectively. DNA methylation status was assessed via methylation-specific PCR (MSP). The U266 MM cell line was treated with the demethylating agent decitabine (DAC) to evaluate its effects on RASD1 expression and apoptosis.

RESULTS

RASD1 mRNA and protein expression were significantly downregulated in patients with MM compared to healthy controls (P < 0.001). Low RASD1 mRNA levels correlated significantly with advanced DS stage, anemia, hypercalcemia, and elevated M-protein concentrations (P < 0.05). The receiver operating characteristic curve indicated that RASD1 mRNA expression was a robust discriminator between patients with MM and healthy individuals (area under the curve = 0.882, sensitivity = 100%, specificity = 75%). MSP analysis revealed RASD1 promoter hypermethylation in patients with MM, whereas controls exhibited hypomethylation. Treatment of U266 cells with DAC restored RASD1 expression and significantly increased apoptosis compared with controls (12.08% vs. 5.04%, P < 0.01).

CONCLUSION

RASD1 is frequently silenced in MM through promoter hypermethylation. This epigenetic inactivation is associated with adverse clinical features and enhanced cell survival, supporting a tumor suppressor role for RASD1 in MM pathogenesis.