盆腹腔转移是卵巢癌患者死亡的重要原因，肿瘤的转移依赖于肿瘤细胞的运动性增强。SIK2在部分浆液性卵巢癌中高表达，且与患者的不良预后有关，SIK2高表达的卵巢癌更易发生转移，但具体机制尚未完全阐明。我们的前期研究发现SIK2基因敲减后细胞的迁移和侵袭能力明显下降，细胞应力纤维形成受限，NMⅡ调节轻链MYL9磷酸化水平明显降低，NMⅡ是细胞运动的重要动力。蛋白序列分析和体外蛋白激酶活性实验发现MYLK是SIK2的直接底物，MYLK可以磷酸化MYL9，MYLK基因敲减部分模拟了SIK2基因敲减的效果，提示SIK2可能通过MYLK影响MYL9磷酸化。我们拟从临床样本、体外细胞分子实验、动物实验三个层次证明SIK2通过使MYLK-MYL9产生级联磷酸化，调节NMⅡ活性，增强细胞的运动能力，促进卵巢癌转移，有助于进一步阐明SIK2在卵巢癌转移中的作用机制，为靶向SIK2治疗转移性卵巢癌提供理论依据。

Abdominal metastasis is the major cause of death in ovarian cancer patients, which is largely dependent on enhanced motility of cancer cells. SIK2 is overexpressed in a fraction of ovarian cancer patients and associated with poor prognosis. Ovarian cancer which have high expression of SIK2 are more prone to abdomen metastases, however, the mechanism is still elusive. We demonstrated that SIK2 knockdown in ovarian cancer cells decreased cell migration and invasion, and attenuated intracellular stress fiber formation, as well as NMⅡregulatory light chain MYL9 phosphorylation on Ser19 which is pivotal to cell motility. Protein motif scan and in vitro kinase assay showed that MYLK, which phosphorylates MYL9, is a direct substrate of SIK2. MYLK knockdown partially recapitulated cell motility deficiency caused by SIK2 knockdown. These data indicates that SIK2 regulates MYL9 activity by phosphorylating MYLK. Through clinical investigation, in vitro assay and animal study, we aim to demonstrate that SIK2 promotes ovarian cancer cell motility and metastasis by triggering MYLK-MYL9 phosphorylation cascade and enhancing NMⅡactivity. Our study helps to illuminate the role of SIK2 in ovarian cancer metastasis, and provides SIK2 as a novel therapeutic target in metastatic ovarian cancer treatment.