Regulation of sphingolipid metabolism plays a role in cellular homeostasis, and dysregulation of these pathways is involved in cancer progression. Previously, our reports identified ceramide as an anti-metastatic lipid. In the present study, we investigated the biochemical alterations in ceramide-centered metabolism of sphingolipids that were associated with metastatic potential. We established metastasis-prone sublines of SKOV3 ovarian cancer cells using an in vivo selection method. These cells showed decreases in ceramide levels and ceramide synthase (CerS) 2 expression. Moreover, CerS2 downregulation in ovarian cancer cells promoted metastasis in vivo and potentiated cell motility and invasiveness. Moreover, CerS2 knock-in suppressed the formation of lamellipodia required for cell motility in this cell line. In order to define specific roles of ceramide species in cell motility controlled by CerS2, the effect of exogenous long- and very long-chain ceramide species on the formation of lamellipodia was evaluated. Treatment with distinct ceramides increased cellular ceramides and had inhibitory effects on the formation of lamellipodia. Interestingly, blocking the recycling pathway of ceramides by a CerS inhibitor was ineffective in the suppression of exogenous C24:1 -ceramide for the formation of lamellipodia. These results suggested that C24:1 -ceramide, a CerS2 metabolite, predominantly suppresses the formation of lamellipodia without the requirement for deacylation/reacylation. Moreover, knockdown of neutral ceramidase suppressed the formation of lamellipodia concomitant with upregulation of C24:1 -ceramide. Collectively, the CerS2-C24:1 -ceramide axis, which may be countered by neutral ceramidase, is suggested to limit cell motility and metastatic potential. These findings may provide insights that lead to further development of ceramide-based therapy and biomarkers for metastatic ovarian cancer.

中文翻译：

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神经酰胺合酶 2-C 24:1-神经酰胺轴限制卵巢癌细胞的转移潜能

鞘脂代谢的调节在细胞稳态中发挥作用，这些途径的失调与癌症进展有关。以前，我们的报告将神经酰胺确定为一种抗转移脂质。在本研究中，我们研究了与转移潜能相关的以神经酰胺为中心的鞘脂代谢的生化变化。我们使用体内选择方法建立了易于转移的 SKOV3 卵巢癌细胞亚系。这些细胞表现出神经酰胺水平和神经酰胺合酶 (CerS) 2 表达降低。此外，卵巢癌细胞中 CerS2 的下调促进了体内转移并增强了细胞运动性和侵袭性。此外，CerS2 敲入抑制了该细胞系中细胞运动所需的片状伪足的形成。为了确定神经酰胺物质在 CerS2 控制的细胞运动中的特定作用，评估了外源性长链和超长链神经酰胺物质对片状伪足形成的影响。用不同的神经酰胺处理增加了细胞神经酰胺并对片状伪足的形成有抑制作用。有趣的是，通过 CerS 抑制剂阻断神经酰胺的循环途径在抑制外源 C24:1-神经酰胺形成片状伪足方面无效。这些结果表明，C24:1-神经酰胺，一种 CerS2 代谢物，主要抑制片状伪足的形成，而不需要脱酰/再酰化。此外，中性神经酰胺酶的敲低抑制了片状伪足的形成，同时C24:1-神经酰胺的上调。总的来说，CerS2-C24：1-神经酰胺轴可以被中性神经酰胺酶抵消，被认为可以限制细胞运动和转移潜能。这些发现可能会为进一步开发基于神经酰胺的疗法和转移性卵巢癌的生物标志物提供见解。