Expression of small glutamine-rich tetratrico peptide repeat-containing protein alpha and clinical significance in breast cancer

Objective To study the expression of small glutamine-rich tetratrico peptide repeat-containing protein alpha (SGTA) in human breast cancer and its relationship with clinicopathological features. Methods The SGTA expression in breast cancer was detected by Western blotting in 8 paired fresh tissues and immunohistochemistry on 128 parffin-embedded slices, and the relationship of SGTA and proliferating cell nuclear antigen (Ki-67) with the clinical parameters was analyzed. Serum starvation and refeeding was performed on MG-132 cells to study the role SGTA played in cell cycle. Results SGTA was highly expressed in breast cancer. The results showed that the expression of SGTA was low in well-differentiated breast cancer tissues, which was consistent with the Ki-67 expression. Multivariate analysis showed that SGTA protein in breast cancer was significantly correlated with histological grade (P=0.000), pTNM staging (P=0.000) as well as Ki-67 (P=0.021), but not with other parameters such as age, estrogen receptor (ER), progesterone receptor (PR), human epidermalgrowth factor receptor-2 (Her-2), histological type, lymph node metastasis and tumor size. Cox’s proportional hazards model showed that SGTA [Hazard ratio (HR)=2.410, 95% confidence interval (CI): 1.075-5.408, P=0.033] might be an independent indicator for breast cancer. Besides, survival curve analysis also showed that high SGTA expression was correlated with a poor prognosis (42.9% vs. 84.5%, P=0.000). Conclusion SGTA may play a role in breast cancer cell proliferation. The abnormal expression of SGTA may be closely related to the initiation and progress of breast cancer. Key words: Breast cancer; Small glutamine-rich tetratrico peptide repeat-containing protein alpha; Prognosis; Proliferation