酪氨酸激酶Syk两种蛋白异构体在乳腺癌细胞内的分布

目的 观察长脾脏酪氨酸激酶[Syk（L）]和短脾脏酪氮酸激酶[Syk（S）]在乳腺癌细胞中的分布。方法 采用胞核、胞质分离技术和Western blot的方法检测乳腺癌细胞系BT474和MIM68中两种Syk蛋白异构体的细胞内分布。构建表达Syk（L）或Syk（S）的MIM35稳定细胞克隆，采用细胞胞核、胞质分离方法和免疫组织化学的方法观察Syk（L）及Syk（S）在细胞内的分布。结果 在乳腺癌细胞系BT474和MIM68中，Syk（L）在细胞质、细胞核内均有表达，Syk（S）只表达在细胞质中。MB435-Syk（L）稳定细胞株中的Syk（L）在细胞质、细胞核内均有表达，MB435-Syk（S）稳定细胞株中的Syk（S）只分布在细胞质内。结论 在乳腺癌细胞中，Syk（L）可由细胞质移位到细胞核内，而Syk（S）只存在于细胞质中。Syk（L）的抑癌功能可能与它的细胞核内功能有关。

The localization of 2 Syk isoforms in breast cancer cells

Objective To explore the localization of Syk(L)and Syk(S)in breast cancer cells. Methods Cytosolic and nuclear fractionation experiments were used to separate the subcellular cell lysate of BT474 and MB468 ,and Western blot was used to analyze the localization of Syk(L)and Syk(S)from the cells.Stable clones of Syk(L)or Syk(S)expression were made from Syk negative cell line MB435. Cytosolic and nuclear fractionation and immunohistochemistry were used to analyze the localization of Syk (L)and Syk(S).Results Syk(L)was expressed in both cytoplasm and nucleus in breast cancer cell lines BT474 and MB468,while Syk(S)was only expressed in cytoplasm.The Syk(L)or Syk(S)stable clones made from MB435 showed the same results as breast cancer cell lines BT474 and MB468 in both the cytosolic and nuclear fractionation and immunohistochemical experiments.Conclusion Syk(L)was able to translocate to nucleus from cytoplasm in breast cancer cells and Syk(S)was only located in cyto- plasm.The translocation of Syk(L)to nucleus maybe was associated with its tumor suppression function.