Background:Colorectal cancer (CRC) is among the most prevalent and lethal cancers globally, with liver metastasis representing the leading cause of CRC-related mortality. Proprotein convertase subtilisin/kexin type 9 (PCSK9) has recently gained attention due to its overexpression in colorectal tumor tissues and its potential role in driving metastatic progression. This aims to investigate the involvement of PCSK9 in the liver metastatic niche, focusing on its effects on liver sinusoidal endothelial cells (LSECs), key components of the liver microenvironment.Methods:LSECs were stimulated with conditioned media derived from differentiated colorectal cancer cells and cancer stem cells (CSCs), the latter generated by reprogramming SW620 and CT26 cell lines. RNA sequencing was used to profile gene expression in LSECs. PCSK9 mRNA and protein levels were quantified by qPCR and Western blotting, respectively. PCSK9 expression in CRC liver metastases was evaluated by immunofluorescent staining.Results: PCSK9 was detected in both human and murine LSECs and significantly upregulated following exposure to CSC-conditioned media. Immunofluorescent staining confirmed PCSK9 expression in LSECs within CRC liver metastases. Total RNA sequencing revealed that a pre-treatment of LSECs with the PCSK9 inhibitor PF-06446864 prior to CSC stimulation seems to reduce the expression of microRNAs linked to cell migration and proliferation. Functional assays demonstrated that CSC-conditioned media enhanced LSEC proliferation and migration, effects reversed by PCSK9 inhibition.Conclusions:PCSK9 promotes the activation of LSECs in response to colorectal CSCs, contributing to a pro-metastatic phenotype. These findings highlight PCSK9 as a potential therapeutic target in colorectal liver metastasis.
背景：结直肠癌是全球范围内最常见且致死率最高的癌症之一，其中肝转移是导致结直肠癌相关死亡的主要原因。前蛋白转化酶枯草溶菌素9型因其在结直肠肿瘤组织中的过表达及其在驱动转移进展中的潜在作用而受到关注。本研究旨在探讨PCSK9在肝转移微环境中的作用，重点关注其对肝脏微环境关键组分——肝窦内皮细胞的影响。 方法：使用分化型结直肠癌细胞及通过重编程SW620和CT26细胞系生成的癌症干细胞的条件培养基刺激LSECs。采用RNA测序技术分析LSECs的基因表达谱，通过qPCR和Western blotting分别定量检测PCSK9 mRNA及蛋白水平，并运用免疫荧光染色评估PCSK9在结直肠癌肝转移灶中的表达情况。 结果：在人源及鼠源LSECs中均检测到PCSK9表达，且在CSCs条件培养基刺激后显著上调。免疫荧光染色证实结直肠癌肝转移灶内的LSECs存在PCSK9表达。全转录组测序显示，在CSCs刺激前使用PCSK9抑制剂PF-06446864预处理LSECs，可降低与细胞迁移和增殖相关的microRNAs表达。功能实验表明CSCs条件培养基能增强LSECs的增殖和迁移能力，而PCSK9抑制可逆转此效应。 结论：PCSK9通过响应结直肠癌干细胞促进LSECs活化，从而形成促转移表型。这些发现提示PCSK9可能成为结直肠癌肝转移的潜在治疗靶点。
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