Loss of TACSTD2 contributed to squamous cell carcinoma progression through attenuating TAp63-dependent apoptosis

Tumor-associated calcium signal transducer 2 (TACSTD2), a calcium signal transducer, is universally expressed in stratified squamous epithelia of many organs, including skin, esophagus and cervix. Although TACSTD2, was reported to be overexpressed in many epithelial tumors, which has increased interest in using it as a molecular target for cancer therapy, the role of TACSTD2 in carcinogenesis of squamous cell carcinoma (SCC) is largely unclear and controversial. To explore the role of TACSTD2, temporal-spatial expression of TACSTD2 was analyzed in both normal and SCC tissues. Our data demonstrate that Tacstd2 expression and membrane localization are tightly associated with stratified epithelial homeostasis, while loss of TACSTD2 was identified in poorly differentiated SCC tissues collected from cervix, esophagus, head and neck. Gradual loss of TACSTD2 was correlated with stepwise progression of SCC. Consistent with these in vivo observations, our data show that inhibition of Tacstd2 expression significantly inhibited chemotherapeutic reagent-induced apoptosis, and TACSTD2 regulated apoptotic gene expression through P63 containing the transactivation domain (TAp63). These findings indicated that loss of TACSTD2 could promote SCC progression and treatment resistance through attenuating chemotherapeutic reagent-induced apoptosis through TAp63, and TACSTD2 could be used as a marker for pathological grading of SCC.