Preliminary Exploration of MAGE-B1, -B4, -B5, and -B10 mRNA Expression in Canine Mammary Tumors in Dogs

The melanoma-associated antigen gene (MAGE) is a key target in cancer immunotherapy. Given the potential of MAGE-B genes in veterinary immunotherapy for canine mammary tumors (CMTs), this study investigated the mRNA expression of <i>MAGE-B1</i>, <i>-B4</i>, <i>-B5</i>, and <i>-B10</i> in CMT tissues and cells from dogs. Quantitative real-time PCR was used to analyze 28 CMT tissue samples, including 4 benign and 24 malignant tumors (13 simple carcinomas, 6 complex carcinomas, 3 carcinosarcomas, and 2 fibrosarcomas). Benign mixed tumor and complex carcinoma-type CMT cells were cultured and treated with a DNA methylase inhibitor (5-aza-2'-deoxycytidine; 5-aza-CdR) and a histone deacetylase inhibitor (Trichostatin A; TSA) under the following four conditions: (1) 5-aza-CdR for 72 h; (2) TSA for 24 h; (3) 5-aza-CdR for 48 h followed by TSA for 24 h; and (4) control. <i>MAGE-B1</i> and <i>-B4</i> showed the highest expression in the CMT samples (100% and 89.29%, respectively), followed by <i>MAGE-B10</i> (82.14%). Carcinosarcomas and simple anaplastic carcinomas had significantly higher MAGE-B expression levels than simple tubulopapillary carcinomas (<i>p</i> < 0.05). 5-aza-CdR treatment increased MAGE-B expression, whereas TSA had a mild effect. Further research involving larger cohorts is needed to confirm these findings.