Sperm-Associated Antigen 9 as a Candidate Diagnostic and Prognostic Biomarker in Breast Cancer

Background: Cancer/testis antigens are a unique class of tumor antigens with normal expressions restricted to the testis and various cancers, but not in adult somatic tissues. Sperm-associated antigen 9 (SPAG9) has been introduced as a new member of Cancer Testis Antigens family involved in c-Jun-NH2-kinase signaling module. The objective of this research was to investigate the potential of SPAG9 as a diagnostic and prognostic biomarker in breast cancer. We further aimed to find any significant association between SPAG9 expression and clinicopathologic features of the cancer. Methods: In this retrospective study, 35 breast cancer tissues and 35 adjacent non-cancerous tissues were collected and examined using RT-PCR to explore SPAG9 mRNA expression. Statistical analysis was done utilizing SPSS 22.0 software. Results: Unexpectedly, we detected SPAG9 expression in 54% of adjacent non-cancerous tissues. Moreover, SPAG9 mRNA was expressed in 57% of cancerous tissues. Statistical analysis showed a significant association between SPAG9 expression and tumor size, lymph node metastasis, and cancer stage. Conclusion: The association between the gene expression and tumor size, lymph, node and metastasis, and cancer stage suggests that SPAG9 can potentially be considered as a prognostic biomarker in breast cancer. However, it may not be a candidate diagnostic biomarker.