Zitkute Vilmante, Kukcinaviciute Egle, Jonusiene Violeta, Starkuviene Vytaute, Sasnauskiene Ausra
Department of Biochemistry and Molecular Biology, Institute of Biosciences, Life Sciences Center, Vilnius University, Vilnius, Lithuania.
BioQuant, Heidelberg University, Heidelberg, Germany.
J Cell Biochem. 2022 Jun;123(6):1103-1115. doi: 10.1002/jcb.30267. Epub 2022 May 1.
Macroautophagy (hereafter autophagy) is one of the adaptive pathways that contribute to cancer cell chemoresistance. Despite the fact that autophagy can both promote and inhibit cell death, there is mounting evidence that in the context of anticancer treatment, it predominantly functions as a cell survival mechanism. Therefore, silencing of key autophagy genes emerges as a potent strategy to reduce chemoresistance. Though the importance of autophagy in chemoresistance is established, the changes in autophagy in the case of acquired chemoresistance are poorly understood. In this study, we aimed to determine the changes of autophagy in the cellular model of acquired chemoresistance of colorectal cancer cell lines HCT116 and SW620, induced by 5-fluorouracil (5-FU) or oxaliplatin (OxaPt) treatment, and determine the susceptible factors for autophagy inhibition. Our results demonstrate that in the context of autophagy, 5-FU and OxaPt have different effects on HCT116 and SW620 cell lines and their chemoresistant sublines. 5-FU inhibits autophagic flux, while changes in the flux after OxaPt treatment are cell type- and dose-dependent, inducing autophagy reduction or increase. The chemoresistant subline of HCT116 cells derived by OxaPt differs from the subline derived by 5-FU treatment - it responds to OxaPt by upregulating ATG7 protein level and autophagic flux, in contrast to downregulation in cells derived by 5-FU. Moreover, 5-FU and OxaPt treatments significantly modulate protein levels of core-autophagy proteins ATG7 and ATG12. The potential effects of 5-FU and OxaPt on ATG protein levels should be taken into account to reduce chemoresistance by applying small interferingRNAs, targeting ATG proteins.
巨自噬（以下简称自噬）是导致癌细胞化疗耐药的适应性途径之一。尽管自噬既能促进也能抑制细胞死亡，但越来越多的证据表明，在抗癌治疗的背景下，它主要作为一种细胞存活机制发挥作用。因此，沉默关键自噬基因成为降低化疗耐药性的有效策略。虽然自噬在化疗耐药中的重要性已得到确立，但对于获得性化疗耐药情况下自噬的变化却知之甚少。在本研究中，我们旨在确定经5-氟尿嘧啶（5-FU）或奥沙利铂（OxaPt）处理诱导的结直肠癌细胞系HCT116和SW620获得性化疗耐药细胞模型中自噬的变化，并确定自噬抑制的易感因素。我们的结果表明，在自噬背景下，5-FU和OxaPt对HCT116和SW620细胞系及其化疗耐药亚系有不同影响。5-FU抑制自噬通量，而OxaPt处理后通量的变化则取决于细胞类型和剂量，可导致自噬减少或增加。由OxaPt诱导产生的HCT116细胞化疗耐药亚系与由5-FU处理产生的亚系不同——它通过上调ATG7蛋白水平和自噬通量来响应OxaPt，而5-FU诱导产生的细胞则下调。此外，5-FU和OxaPt处理显著调节核心自噬蛋白ATG7和ATG12的蛋白水平。在应用靶向ATG蛋白的小干扰RNA降低化疗耐药性时，应考虑5-FU和OxaPt对ATG蛋白水平的潜在影响。
