肝细胞癌（HCC）的结局因其复杂的分子特征和多变的肿瘤微环境（TME）而受到限制。本研究重点阐明母胚胎亮氨酸拉链激酶（MELK）在HCC肿瘤发生、进展和转移中的功能作用，并探讨MELK对TME中免疫细胞调节的影响，同时阐明相应的信号网络。生物信息学分析用于验证 MELK 对 HCC 的预后价值。小鼠异种移植试验和 HCC 肺转移小鼠模型证实了 MELK 在 HCC 肿瘤发生和转移中的作用。应用荧光素酶检测、RNA测序、免疫纯化质谱（IP-MS）和免疫共沉淀（CoIP）等方法探讨MELK在HCC中的上游调控因子、下游必需分子及相应机制，证实MELK是HCC可靠的预后因素并确定 MELK 是促进 HCC 肿瘤发生、进展和转移的有效候选者； MELK的作用依赖于对上游因子miR-505-3p的靶向调控以及与STAT3的相互作用，诱导STAT3磷酸化并增加其靶基因CCL2在HCC中的表达。此外，我们证实肿瘤细胞内在的 MELK 抑制有利于刺激 M1 巨噬细胞极化、阻碍 M2 巨噬细胞极化和诱导 CD8  T 细胞募集，这些都依赖于 CCL2 表达的改变。重要的是，MELK 抑制放大了 RT 相关的免疫效应，从而与 RT 协同发挥显着的抗肿瘤作用。 OTS167 是 MELK 的抑制剂，也被证明可以有效抑制 HCC 的生长和进展，并与放射治疗 (RT) 结合发挥卓越的抗肿瘤作用。总而言之，我们的研究结果强调了 MELK 作为分子治疗中有希望的靶点的功能作用并结合放疗治疗以提高 HCC 的抗肿瘤效果。© 2024。作者。

The outcome of hepatocellular carcinoma (HCC) is limited by its complex molecular characteristics and changeable tumor microenvironment (TME). Here we focused on elucidating the functional consequences of Maternal embryonic leucine zipper kinase (MELK) in the tumorigenesis, progression and metastasis of HCC, and exploring the effect of MELK on immune cell regulation in the TME, meanwhile clarifying the corresponding signaling networks.Bioinformatic analysis was used to validate the prognostic value of MELK for HCC. Murine xenograft assays and HCC lung metastasis mouse model confirmed the role of MELK in tumorigenesis and metastasis in HCC. Luciferase assays, RNA sequencing, immunopurification-mass spectrometry (IP-MS) and coimmunoprecipitation (CoIP) were applied to explore the upstream regulators, downstream essential molecules and corresponding mechanisms of MELK in HCC.We confirmed MELK to be a reliable prognostic factor of HCC and identified MELK as an effective candidate in facilitating the tumorigenesis, progression, and metastasis of HCC; the effects of MELK depended on the targeted regulation of the upstream factor miR-505-3p and interaction with STAT3, which induced STAT3 phosphorylation and increased the expression of its target gene CCL2 in HCC. In addition, we confirmed that tumor cell-intrinsic MELK inhibition is beneficial in stimulating M1 macrophage polarization, hindering M2 macrophage polarization and inducing CD8 + T-cell recruitment, which are dependent on the alteration of CCL2 expression. Importantly, MELK inhibition amplified RT-related immune effects, thereby synergizing with RT to exert substantial antitumor effects. OTS167, an inhibitor of MELK, was also proven to effectively impair the growth and progression of HCC and exert a superior antitumor effect in combination with radiotherapy (RT).Altogether, our findings highlight the functional role of MELK as a promising target in molecular therapy and in the combination of RT therapy to improve antitumor effect for HCC.© 2024. The Author(s).