Emerging role of sperm-associated antigen 9 in tumorigenesis.

Sperm-associated antigen 9 (SPAG9) is a new member of cancer testis antigen and belongs to c-Jun NH2-terminal kinase (JNK) interacting protein (JIP) family. SPAG9 is highly expressed in a variety of tumors patients, and induces immune response in the host. SPAG9 regulates JNK and mitogen-activated protein kinases (MAPKs) signaling pathways which promote the growth, metastasis and drug resistance of tumors. In addition, SPAG9 modulates cell cycle progression and upregulates matrix metalloproteinases during the progression of tumors. Silencing SPAG9 expression could suppress the development of tumors. This review summarizes recent progress in our understanding of the emerging role of SPAG9 in tumorigenesis and highlights the potential of SPAG9 as a novel target for cancer diagnosis and therapy.