Yanagi Teruki, Nagai Ko, Shimizu Hiroshi, Matsuzawa Shu-Ichi
Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California, USA.
Department of Dermatology, Hokkaido University Graduate School of Medicine, Sapporo, Japan.
Oncotarget. 2017 Jul 22;8(40):68448-68459. doi: 10.18632/oncotarget.19497. eCollection 2017 Sep 15.
Melanoma-associated antigen family A (MAGE-A) is a family of cancer/testis antigens that are expressed in malignant tumors but not in normal tissues other than the testes. MAGE-A12 is a MAGE-A family gene whose tumorigenic function in cancer cells remains unclear. Searches of the Oncomine and NextBio databases revealed that malignant tumors show up-regulation of mRNA relative to corresponding normal tissue. In PPC1 primary prostatic carcinoma cells and in HCT116 colorectal cancer cells (wild type and p53-depleted), gene knockdown using siRNA or shRNA diminishes cancer cell proliferation as assessed by cellular ATP levels, cell counting, and clonogenic assays. FACS analyses of annexin V-PI staining and DNA content show that knockdown causes G2/M arrest and apoptosis. In tumor xenografts of HCT116 cells, conditional knockdown of suppresses tumor growth. The depletion of leads to the accumulation of tumor suppressor p21 in PPC1, HCT116, and p53-depleted HCT116 cells. Conversely, knockdown partially rescues the viability of PPC1 cells transfected with siRNA targeting , while p21 overexpression leads to proliferation arrest in PPC-1 cells. Furthermore, exogenous MAGE-A12 expression promotes the ubiquitination of p21. Our findings reveal that MAGE-A12 plays crucial roles in p21 stability and tumor growth, suggesting that MAGE-A12 could provide a novel target for cancer treatment.
黑色素瘤相关抗原A家族（MAGE-A）是一类癌胚抗原，在恶性肿瘤中表达，但在睾丸以外的正常组织中不表达。MAGE-A12是MAGE-A家族基因，其在癌细胞中的致瘤功能尚不清楚。对Oncomine和NextBio数据库的检索显示，相对于相应的正常组织，恶性肿瘤中mRNA呈上调。在PPC1原发性前列腺癌细胞和HCT116结肠癌细胞（野生型和p53缺失型）中，使用siRNA或shRNA进行基因敲低可减少癌细胞增殖，这通过细胞ATP水平、细胞计数和克隆形成试验进行评估。对膜联蛋白V-PI染色和DNA含量的流式细胞术分析表明，基因敲低导致G2/M期阻滞和细胞凋亡。在HCT116细胞的肿瘤异种移植中，MAGE-A12的条件性敲低抑制肿瘤生长。MAGE-A12的缺失导致PPC1、HCT116和p53缺失的HCT116细胞中肿瘤抑制因子p21的积累。相反，MAGE-A12敲低部分挽救了用靶向p21的siRNA转染的PPC1细胞的活力，而p21过表达导致PPC-1细胞增殖停滞。此外，外源性MAGE-A12表达促进p21的泛素化。我们的研究结果表明，MAGE-A12在p21稳定性和肿瘤生长中起关键作用，提示MAGE-A12可能为癌症治疗提供新靶点。
