Background: SMAD4 is a down-stream effector of transforming growth factor-beta (TGF-B) signaling pathway. Although the tumor suppressor role of this prognostic biomarker has been previously studied in many malignancies, its role as a prognostic biomarker in breast cancer has yet to be confirmed. The regulatory effect of microRNA-483-3p (miR-483-3p) as a tumor suppressor on SMAD4 has also been investigated, and a correlation has been reported in some malignancies such as the pancreatic cancer. Objectives: This study aimed to assess the expression of miR-483-3p and its effect on the expression of SMAD4 gene in breast cancer patients. Materials and Methods: The expression of SMAD4 gene was evaluated in 51 paired tumoral tissue/adjacent healthy tissue specimens by real-time polymerase chain reaction (PCR). GAPDH gene was used as the control (reference) gene. The correlation of SMAD4 expression with clinicopathological features was also evaluated. The expression of miR-483-3p was then evaluated in 16 SMAD4 negative tumoral specimens by real-time PCR, to assess its effect on the expression of SMAD4 by REST 2009 software. Data were analyzed by the Chi-square test. Results: The results showed no significant correlation between the expression of miR-483-3p and SMAD4 (P>0.05). Conclusion: It appears that alterations in the expression of miR-483-3p have no significant effect on the expression of SMAD4 gene in breast cancer patients.
