微管蛋白酪氨酸连接酶类似物12通过干扰微管蛋白酪氨酸硝基化促进Hep-2细胞生长

硝基化酪氨酸与酪氨酸在结构上相似，它在病理情况下会出现,并在细胞内与微管蛋白结合，从而阻碍微管的正常功能. 硝基化酪氨酸在肿瘤中的作用，目前研究甚少.本文利用头颈鳞癌Hep-2细胞株，研究微管蛋白酪氨酸连接酶类似物12（tubulin tyrosine ligase like 12，TTLL12）和硝基化酪氨酸对头颈鳞癌Hep-2生长的影响，通过Western 印迹试验和MTT试验发现，随着硝基化酪氨酸的浓度升高，细胞内生成的硝基化酪氨酸微管蛋白含量也增高，同时细胞生长受抑制的程度显著增高; 对建立的TTLL12高表达细胞株加入硝基化酪氨酸培养，结果显示，TTLL12高表达细胞株内的硝基化酪氨酸微管蛋白含量明显低于对照组细胞；对照组细胞的生长明显受到抑制，而高表达细胞株的生长无明显改变，两者的细胞生长有显著性差异（P＜0.05）.本研究结果提示，TTLL12可通过阻碍硝基化酪氨酸与微管蛋白的结合，使头颈鳞癌Hep-2细胞逃避硝基化酪氨酸的打击. 对这一调控机制的进一步研究，必将有助于控制肿瘤细胞的生长,为治疗肿瘤寻找到新的治疗靶点.

Tubulin Tyrosine Ligase Like 12 Promoted the Growth of Hep-2 Cells by Interfering with Nitrotyrosine

Nitrotyrosine, a structural analogue of tyrosine, is present in cells in pathological conditions and is incorporated on the tubulin，which hampers the normal function of microtubules. Studies regarding the functional aspects of nitrotyrosination in tumor are just a few. In this article, the effects of nitrotyrosine and tubulin tyrosine ligase like 12 (TTLL12) on the growth of Hep-2 cells were investigated. Western blotting showed that TTLL12 and α-tubulin nitrotyrosination expression increased in Hep-2 cells, and the concentration of α-tubulin nitrotyrosination increased with the increasing concentration of nitrotyrosine. MTT assay showed that cell growth was inhibited with the increasing concentration of nitrotyrosine; TTLL12 stable overexpression Hep-2 cell line was built. After overexpression and control Hep-2 cells were treated with nitrotyrosine, α-tubulin nitrotyrosination was significantly lower in overexpression cells than control cells; the growth of control cells were significantly inhibited, while no visible change was found in the growth of overexpression cells, there was significant difference (P <005) between the growth of two species cells. These data indicated that TTLL12 hampers the combination of nitrotyrosine and tubulin, so that hep-2 cell is able to survive in the presence of nitrotyrosine. The further study of the mechanism of this regulation will help to control tumor growth, and find the new therapeutic target for the treatment of cancer.