紫杉醇类诱导的LIMD1磷酸化调控非小细胞肺癌恶性表型增强及化疗抵抗的作用及机制研究

Taxanes (e.g. Taxol and Docetaxel) are one of the major chemotherapy strategies; however, the efficacy is limited mainly due to drug resistance. LIMD1 is identified as a tumor suppressor in variety types of tumor, especially in non-small cell lung cancer (NSCLC). Our preliminary data showed that LIMD1 is phosphorylated by CDK1 when treating NSCLC cells with Taxol, and phosphorylated LIMD1 reverses its tumor suppressive function and subsequently increases the tumor’s malignancy and chemo-resistance. Based these data and relevant publications, we hypothesize that the Taxane-induced LIMD1 phosphorylation is involved in the upregulated malignant phenotype and chemo-resistance of NSCLC; inhibition of LIMD1 phosphorylation may impede or restrain the Taxane-induced chemo-resistance. In this project, we for the first time systemically study the influence of Taxol on NSCLC malignant phenotype and the underlying mechanisms. In addition, we will try to explore the potential possibility and benefits of combining Taxanes and CDK1 inhibitors for NSCLC treatment. The results of this project may provide theoretic basis and experimental evidence for the modification of Taxane-based drug therapy.

紫杉醇类药物是治疗肿瘤的主要化疗药物之一，其疗效受限的主要原因是耐药现象的出现。LIMD1(LIM domain-containing protein 1)是一种抑癌基因，在多种肿瘤组织（尤其是非小细胞肺癌）中发挥抑癌作用。我们前期研究发现，紫杉醇处理非小细胞肺癌细胞后诱导LIMD1磷酸化，其相关的磷酸激酶为CDK1。LIMD1磷酸化后丧失其抑癌作用，增加肺癌细胞对紫杉醇的化疗抵抗。基于前期实验结果及相关文献报道，我们提出假说：紫杉醇类药物能够诱导LIMD1被CDK1磷酸化，进而增强肿瘤的恶性表型及化疗抵抗；抑制LIMD1磷酸化可能克服或延缓紫杉醇类药物化疗抵抗的产生。本课题首次研究并探索紫杉醇类诱导的LIMD1磷酸化对肺癌细胞恶性表型的影响及其分子机制，并进一步探讨联合应用紫杉醇类药物及CDK1抑制剂治疗非小细胞肺癌的可能性，为紫杉醇类药物治疗策略的改进提供理论基础和实验依据。

LIMD1是Zyxin家族蛋白的成员，在肺癌中起肿瘤抑制作用。LIMD1已经被证明可以调节Hippo-YAP信号通路。我们的研究发现LIMD1在有丝分裂中磷酸化调节的新机制及其在癌细胞生长中的生物学效应。我们发现细胞周期蛋白依赖激酶1（CDK1）和c-Jun NH2末端激酶1/2在体外药物诱导的有丝分裂和正常有丝分裂过程中可磷酸化LIMD1。我们挖掘出四个磷酸化位点，分别为S272、S277、S421和S424。LIMD1的缺失导致有丝分裂细胞周期缩短，LIMD1的磷酸化是有丝分裂正常进行的必要条件。我们进一步证明，有丝分裂磷酸化缺陷突变体LIMD1-4A在抑制肺癌细胞增殖、锚定生长、细胞迁移和侵袭方面的能力较低。总之，我们的发现揭示了LIMD1在有丝分裂中的一个新的调节机制及其在肿瘤发生中的作用。