Yang Chuanjia, Xu Weixue, Gong Jian, Chai Fang, Cui Dongxu, Liu Zhen
Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang 110004, People's Republic of China.
Department of Clinical Pharmacy, School of Life Science and Pharmaceutical University, Shenyang, People's Republic of China.
Onco Targets Ther. 2020 May 29;13:4855-4863. doi: 10.2147/OTT.S227291. eCollection 2020.
Sineoculis homeobox homolog 1 (Six1) overexpression has been implicated in several human cancers. To date, its clinical significance and potential function in human thyroid cancer remain unclear.
Immunohistochemistry was used to examine the protein expression of BCAT1 in 89 cases of thyroid cancer tissues. We overexpressed and knockdown Six1 in TPC-1 and B-CPAP thyroid cancer cell lines. Biological roles and potential mechanisms of Six1 were examined using CCK-8, colony formation assay, Matrigel invasion assay, Western blot, PCR, ATP assay, and 2-NBDG uptake assay.
We showed that Six1 protein was upregulated in thyroid cancers and was associated with tumor size and nodal metastasis. Analysis of TCGA dataset indicated that Six1 mRNA was higher in thyroid cancers compared with normal thyroid. CCK-8, colony formation and Matrigel invasion assays demonstrated that Six1 overexpression promoted proliferation, colony number and invasion while Six1 siRNA knockdown inhibited the growth rate, colony formation ability and invasive ability in both cell lines. Notably, Six1 upregulated glucose consumption, lactate production level and ATP level. 2-NBDG uptake analysis showed that Six1 overexpression upregulated glucose uptake while Six1 knockdown inhibited glucose uptake. Further analysis revealed that Six1 overexpression upregulated Snail, MMP2 and GLUT3 at both mRNA and protein levels. TCGA analysis demonstrated positive associations between Six1 and Snail, MMP2 and GLUT3 at the mRNA levels.
Taken together, our data demonstrated that Six1 was upregulated in human thyroid cancers and promoted cell proliferation and invasion. Our data also revealed new roles of Six1 in thyroid cancer development by modulating glucose metabolism and invasion, possibly through regulation of Snail, MMP2 and GLUT3.
同源异形盒基因Six1（Sineoculis homeobox homolog 1）的过表达与多种人类癌症有关。迄今为止，其在人类甲状腺癌中的临床意义和潜在功能仍不清楚。
采用免疫组织化学法检测89例甲状腺癌组织中BCAT1的蛋白表达。我们在TPC-1和B-CPAP甲状腺癌细胞系中过表达和敲低Six1。使用CCK-8、集落形成试验、基质胶侵袭试验、蛋白质免疫印迹法、聚合酶链反应、ATP检测和2-NBDG摄取试验检测Six1的生物学作用和潜在机制。
我们发现Six1蛋白在甲状腺癌中上调，且与肿瘤大小和淋巴结转移相关。对癌症基因组图谱（TCGA）数据集的分析表明，与正常甲状腺相比，Six1 mRNA在甲状腺癌中更高。CCK-8、集落形成和基质胶侵袭试验表明，Six1过表达促进增殖、集落数量和侵袭，而Six1小干扰RNA（siRNA）敲低抑制两种细胞系的生长速率、集落形成能力和侵袭能力。值得注意的是，Six1上调葡萄糖消耗、乳酸生成水平和ATP水平。2-NBDG摄取分析表明，Six1过表达上调葡萄糖摄取，而Six1敲低抑制葡萄糖摄取。进一步分析显示，Six1过表达在mRNA和蛋白质水平上均上调Snail、基质金属蛋白酶2（MMP2）和葡萄糖转运蛋白3（GLUT3）。TCGA分析表明，Six1与Snail、MMP2和GLUT3在mRNA水平上呈正相关。
综上所述，我们的数据表明Six1在人类甲状腺癌中上调，并促进细胞增殖和侵袭。我们的数据还揭示了Six1在甲状腺癌发生发展中的新作用，即通过调节葡萄糖代谢和侵袭，可能是通过调控Snail、MMP2和GLUT3来实现的。
