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

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.
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.
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.
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.