Investigation of SRP9 protein expression in breast cancer.

BACKGROUND: Signal recognition particle (SRP) promotes co-translational translocation of the proteins through or into the endoplasmic reticulum membrane and it also has elongation arrest function. SRP9 is one of the six protein subunits of SRP and functions in elongation arrest activity by forming a heterodimeric structure with SRP14. It is one of the substrates of ADAR, which has been found to have a role in breast cancer. This study was conducted to investigate the SRP9 protein expression in normal and tumor tissues of patients with breast cancer and determine its prognostic significance. METHODS AND RESULTS: A total of 32 female patients who were diagnosed as having primary breast cancer and underwent surgery were included in the study. Western Blotting was performed to detect SRP9 protein expression levels in normal and tumor tissue samples. Clinical and pathologic characteristics were analyzed to assess the prognostic significance. SRP9 protein expression was statistically higher in the breast cancer tissue samples compared to normal matched tissue, and the mean SRP9 protein expression levels of breast cancer tissue normal tissue samples were 1.019 ± 1.011 and 0.551 ± 0.456, respectively (p = 0.001). SRP9 protein expression levels in tumor tissue of patients with lymph node metastasis, tumor size > 2 cm, estrogen receptor-positive, progesterone receptor-positive, and HER-2 negative were statistically higher than in normal tissue (p < 0.05). CONCLUSIONS: It is vital to clarify the roles of molecules such as SRP9 in understanding the pathogenesis of breast cancer. In our study, we showed that SRP9 expression increased in breast cancer and was associated with disease-related parameters.