Laboratory of Biomolecular Systems Signaling, Department of Biochemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, Bl. 09i - Sl. 922, Cidade Universitaria, Sao Paulo, SP, CEP 05508-900, Brazil.
Mol Cell Biochem. 2021 Sep;476(9):3393-3405. doi: 10.1007/s11010-021-04167-5. Epub 2021 May 5.
Stearoyl-CoA desaturase (SCD) is a central lipogenic enzyme for the synthesis of monounsaturated fatty acids (MUFA). SCD1 overexpression is associated with a genetic predisposition to hepatocarcinogenesis in mice and rats. This work hypothesized possible roles of SCD1 to genomic stability, lipogenesis, cell proliferation, and survival that contribute to the malignant transformation of non-tumorigenic liver cells. Therefore, HepG2 tumor cells were treated with the SCD1 inhibitor (CAY10566) to ensure a decrease in proliferation/survival, as confirmed by a lipidomic analysis that detected an efficient decrease in the concentration of MUFA. According to that, we switched to a model of normal hepatocytes, the HepaRG cell line, where we: (i) overexpressed SCD1 (HepaRG-SCD1 clones), (ii) inhibited the endogenous SCD1 activity with CAY10566, or (iii) treated with two monounsaturated (oleic OA and/or palmitoleic PA) fatty acids. SCD1 overexpression or MUFA stimulation increased cell proliferation, survival, and the levels of AKT, phospho-AKT(Ser473), and proliferating cell nuclear antigen (PCNA) proteins. By contrast, opposite molecular and cellular responses were observed in HepaRG cells treated with CAY10566. To assess genomic stability, HepaRG-SCD1 clones were treated with ionizing radiation (IR) and presented reduced levels of DNA damage and higher survival at doses of 5 Gy and 10 Gy compared to parental cells. In sum, this work suggests that modulation of SCD1 activity not only plays a role in cell proliferation and survival, but also in maintaining genomic stability, and therefore, contributes to a better understanding of this enzyme in molecular mechanisms of hepatocarcinogenesis projecting SCD1 as a potential translational target.
硬脂酰辅酶 A 去饱和酶 (SCD) 是合成单不饱和脂肪酸 (MUFA) 的关键脂肪生成酶。SCD1 过表达与小鼠和大鼠肝癌的遗传易感性有关。这项工作假设 SCD1 可能在基因组稳定性、脂肪生成、细胞增殖和存活方面发挥作用,这些作用有助于非肿瘤性肝细胞的恶性转化。因此,用 SCD1 抑制剂 (CAY10566) 处理 HepG2 肿瘤细胞,以确保增殖/存活减少,脂质组学分析证实 MUFA 浓度有效降低。根据这一点,我们切换到正常肝细胞模型 HepaRG 细胞系,在该模型中:(i) 过表达 SCD1 (HepaRG-SCD1 克隆),(ii) 用 CAY10566 抑制内源性 SCD1 活性,或 (iii) 用两种单不饱和 (油酸 OA 和/或棕榈油酸 PA) 脂肪酸处理。SCD1 过表达或 MUFA 刺激增加了细胞增殖、存活以及 AKT、磷酸化 AKT(Ser473) 和增殖细胞核抗原 (PCNA) 蛋白的水平。相比之下,在用 CAY10566 处理的 HepaRG 细胞中观察到相反的分子和细胞反应。为了评估基因组稳定性,用电离辐射 (IR) 处理 HepaRG-SCD1 克隆,与亲本细胞相比,在 5 Gy 和 10 Gy 的剂量下,细胞的 DNA 损伤水平降低,存活率更高。总之,这项工作表明,SCD1 活性的调节不仅在细胞增殖和存活中起作用,而且在维持基因组稳定性中起作用,因此有助于更好地理解该酶在肝癌发生的分子机制中,将 SCD1 作为一个潜在的转化靶点。