Abstract：
Fatty acid synthase (FASN) catalyzes the rate-limiting step of cellular lipogenesis. FASN expression is upregulated in various types of cancer cells, implying that FASN is a potential target for cancer therapy. 2-Deoxy-D-glucose (2-DG) specifically targets cancer cells by inhibiting glycolysis and glucose metabolism, resulting in multiple anticancer effects. However, whether the effects of 2-DG involve lipogenic metabolism remains to be elucidated. We investigated the effect of 2-DG administration on FASN expression in HeLa human cervical cancer cells. 2-DG treatment for 24 h decreased FASN mRNA and protein levels and suppressed the activity of an exogenous rat Fasn promoter. The use of a chemical activator or inhibitors or of a mammalian expression plasmid showed that neither AMPK nor the Sp1 transcription factor is responsible for the inhibitory effect of 2-DG on FASN expression. Administration of thapsigargin, an endoplasmic reticulum (ER) stress inducer, or 4-(2-aminoethyl) benzenesulfonyl fluoride (AEBSF), a site 1 protease inhibitor, mimicked the inhibitory effect of 2-DG on FASN expression. 2-DG did not further decrease FASN expression in the presence of thapsigargin or AEBSF. Site 1 protease mediates activation of ATF6, an ER stress mediator, as well as sterol regulatory element-binding protein 1 (SREBP1), a robust transcription factor for FASN. Administration of 2-DG or thapsigargin for 24 h suppressed activation of ATF6 and SREBP1, as did AEBSF. We speculated that these effects of 2-DG or thapsigargin are due to feedback inhibition via increased GRP78 expression following ER stress. Supporting this, exogenous overexpression of GRP78 in HeLa cells suppressed SREBP1 activation and Fasn promoter activity. These results suggest that 2-DG suppresses FASN expression via an ER stress-dependent pathway, providing new insight into the molecular basis of FASN regulation in cancer.
摘要：
脂肪酸合酶(FASN)催化细胞脂肪生成的限速步骤。FASN表达在各种类型的癌细胞中上调，这意味着FASN是癌症治疗的潜在靶点。2-脱氧-D-葡萄糖（2-DG）通过抑制糖酵解和葡萄糖代谢特异性靶向癌细胞，产生多种抗癌作用。然而,2-DG的作用是否涉及脂肪代谢还有待阐明.我们研究了2-DG给药对HeLa人宫颈癌细胞中FASN表达的影响。2-DG处理24小时可降低FASNmRNA和蛋白质水平，并抑制外源性大鼠Fasn启动子的活性。化学活化剂或抑制剂或哺乳动物表达质粒的使用表明，AMPK和Sp1转录因子均不负责2-DG对FASN表达的抑制作用。thapsigargin的管理，内质网（ER）应激诱导剂，或4-（2-氨基乙基）苯磺酰氟（AEBSF），位点1蛋白酶抑制剂，模拟2-DG对FASN表达的抑制作用。2-DG在thapsigargin或AEBSF存在下没有进一步降低FASN表达。位点1蛋白酶介导内质网应激介质ATF6的激活，以及固醇调节元件结合蛋白1（SREBP1），FASN的强大转录因子。2-DG或thapsigargin给药24小时抑制ATF6和SREBP1的激活，AEBSF也是如此。我们推测，2-DG或thapsigargin的这些作用是由于内质网应激后GRP78表达增加的反馈抑制。支持这一点,GRP78在HeLa细胞中的外源过表达抑制了SREBP1的激活和Fasn启动子的活性。这些结果表明，2-DG通过ER应激依赖性途径抑制FASN表达，为癌症中FASN调控的分子基础提供了新的见解。
