Immunohistochemical Expression of Sperm-Associated Antigen 9 in Nonmelanoma Skin Cancer

Sperm-associated antigen 9 (SPAG9) is a scaffold protein for c-Jun-NH2-kinases, which play an important role in cell survival, proliferation, apoptosis, and tumor development. SPAG9 was claimed to be involved in the pathogenesis of carcinoma in different organs. The aim of this work was to investigate its role in the pathogenesis of nonmelanoma skin cancer (NMSC) through its immunohistochemical (IHC) localization in skin biopsies of these tumors. This retrospective and prospective study included 67 cutaneous specimens; 42 of NMSC [ 20 cases with basal cell carcinoma (BCC) and 22 cases with squamous cell carcinoma (SCC)] and 25 normal sun-exposed skin biopsies from age and gender-matched healthy subjects as a control group. SPAG9 expression was evaluated using standard IHC techniques. SPAG9 was expressed in 90% of BCC cases and in 81.8% of SCC cases. Positive expression in inflammatory cells was detected in 100% and 63.6% of BCC and SCC cases, respectively. Positive stromal expression was detected in 20% of BCC cases and was absent in all SCC cases. A significant negative correlation (r = -0.55, P = 0.008) was noted between SPAG9 H score and SCC histological grade and a significant association between SPAG9 H score and tumor grade was also detected where higher values were present in grade I tumors (P = 0.001). SPAG9 was upregulated in NMSC when compared with normal skin. In conclusion, SPAG9 is expressed in NMSC cases. It should be evaluated in large-scale studies to determine if it plays an active pathogenic role or its expression is an epiphenomenon not related to NMSC pathogenesis. Large-scale studies are warranted to determine its potential utility in guiding treatment decisions and following disease progression in theses cases. Its expression in normal skin needs further investigation.