Previously we demonstrated that Ahnak mediates transforming growth factor-β (TGFβ)-induced epithelial-mesenchymal transition (EMT) during tumor metastasis. It is well-known that circulating tumor cells (CTCs) invade the vasculature of adjacent target tissues before working to adapt to the host environments. Currently, the molecular mechanism by which infiltrated tumor cells interact with host cells to survive within target tissue environments is far from clear. Here, we show that Ahnak regulates tumor metastasis through PCSK9 expression. To validate the molecular function of Ahnak in metastasis, B16F10 melanoma cells were injected into WT and Ahnak knockout (Ahnak^−/−) mice. Ahnak^−/− mice were more resistant to the pulmonary metastasis of B16F10 cells compared to wild-type (WT) mice. To investigate the host function of Ahnak in recipient organs against metastasis of melanoma cells, transcriptomic analyses of primary pulmonary endothelial cells from WT or Ahnak^−/− mice in the absence or presence of TGFβ stimulation were performed. We found PCSK9, along with several other candidate genes, was involved in the invasion of melanoma cells into lung tissues. PCSK9 expression in the pulmonary artery was higher in WT mice than Ahnak^−/− mice. To evaluate the host function of PCSK9 in lung tissues during the metastasis of melanoma cells, we established lung epithelial cell-specific tamoxifen-induced PCSK9 conditional KO mice (Scgb1a1-Cre/PCSK9^fl/fl). The pulmonary metastasis of B16F10 cells in Scgb1a1-Cre/PCSK9^fl/fl mice was significantly suppressed, indicating that PCSK9 plays an important role in the metastasis of melanoma cells. Taken together, our data demonstrate that Ahnak regulates metastatic colonization through the regulation of PCSK9 expression.

之前我们证明了 Ahnak 在肿瘤转移过程中介导转化生长因子-β (TGFβ) 诱导的上皮间质转化 (EMT)。众所周知，循环肿瘤细胞 (CTC) 在适应宿主环境之前会侵入邻近靶组织的脉管系统。目前，浸润的肿瘤细胞与宿主细胞相互作用以在靶组织环境中存活的分子机制尚不清楚。在这里，我们表明 Ahnak 通过 PCSK9 表达调节肿瘤转移。为了验证 Ahnak 在转移中的分子功能，将 B16F10 黑色素瘤细胞注射到 WT 和 Ahnak 敲除 (Ahnak ^-/- ) 小鼠中。安纳克^-/-与野生型 (WT) 小鼠相比，小鼠对 B16F10 细胞肺转移的抵抗力更强。为了研究 Ahnak 在受体器官中对抗黑色素瘤细胞转移的宿主功能，在不存在或存在 TGFβ 刺激的情况下，对来自 WT 或 Ahnak ^-/-小鼠的原代肺内皮细胞进行转录组学分析。我们发现 PCSK9 以及其他几个候选基因参与了黑色素瘤细胞侵入肺组织的过程。WT 小鼠肺动脉中的 PCSK9 表达高于 Ahnak ^-/-小鼠。为了评估黑色素瘤细胞转移过程中 PCSK9 在肺组织中的宿主功能，我们建立了肺上皮细胞特异性三苯氧胺诱导的 PCSK9 条件 KO 小鼠 (Scgb1a1-Cre/PCSK9 ^fl/fl）。Scgb1a1-Cre/PCSK9 ^fl/fl小鼠B16F10细胞的肺转移明显受到抑制，表明PCSK9在黑色素瘤细胞的转移中起重要作用。总之，我们的数据表明，Ahnak 通过调节 PCSK9 表达来调节转移性定植。