Tan Qian, Joshua A M, Wang M, Bristow R G, Wouters B G, Allen C J, Tannock Ian F
Department of Medical Biophysics, University Health Network, University of Toronto, Toronto, ON, Canada.
Princess Margaret Cancer Center, 9 floor room 417, 610 University Ave, Toronto, ON, M5G2M9, Canada.
Cancer Chemother Pharmacol. 2017 May;79(5):959-969. doi: 10.1007/s00280-017-3298-5. Epub 2017 Apr 4.
Autophagy is a survival mechanism that allows recycling of cellular breakdown products, particularly in stressed cells. Here we evaluate the hypotheses that up-regulation of autophagy is a common mechanism of resistance to chemotherapy, and that drug resistance can be reversed by inhibiting autophagy with a proton pump inhibitor.
We exposed human PC3, LNCaP and MCF7 cells to seven clinically-used chemotherapy drugs ± pantoprazole, examined the up-regulation of autophagy and the effect on cellular proliferation by Western Blots, MTS assay and colony-forming assay. The distribution of drug effects and of autophagy was quantified in LNCaP tumor sections in relation to blood vessels and hypoxia by immunohistochemistry using γH2AX, cleaved caspase-3 and p62.
All anticancer drugs led to up-regulation of autophagy in cultured tumor cells. Pantoprazole inhibited the induction of autophagy in a time- and dose-dependent manner, and sensitized cancer cells to the seven anti-cancer drugs. Treatment of LNCaP xenografts with paclitaxel induced both DNA damage and autophagy; autophagy was inhibited and markers of toxicity were increased by pantoprazole.
Induction of autophagy is a general mechanism associated with resistance to anticancer drugs and that its inhibition is a promising therapeutic strategy to enhance the effects of chemotherapy and improve clinical outcomes.
自噬是一种生存机制，可使细胞分解产物得以循环利用，尤其是在应激细胞中。在此，我们评估以下假说：自噬上调是化疗耐药的常见机制，并且质子泵抑制剂抑制自噬可逆转耐药性。
我们将人PC3、LNCaP和MCF7细胞暴露于七种临床使用的化疗药物±泮托拉唑，通过蛋白质免疫印迹法、MTS法和集落形成试验检测自噬上调情况及其对细胞增殖的影响。使用γH2AX、裂解的半胱天冬酶-3和p62通过免疫组织化学在LNCaP肿瘤切片中定量药物效应和自噬相对于血管和缺氧的分布。
所有抗癌药物均导致培养的肿瘤细胞中自噬上调。泮托拉唑以时间和剂量依赖性方式抑制自噬诱导，并使癌细胞对七种抗癌药物敏感。用紫杉醇处理LNCaP异种移植瘤可诱导DNA损伤和自噬；泮托拉唑抑制自噬并增加毒性标志物。
自噬诱导是与抗癌药物耐药相关的普遍机制，抑制自噬是增强化疗效果和改善临床结局的一种有前景的治疗策略。
