Pei Guoqing, Luo Meng, Ni Xiaochun, Wu Jugang, Wang Shoulian, Ma Yiwen, Yu Jiwei
Department of General Surgery, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Department of Anaesthesiology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Cell Physiol Biochem. 2018;46(2):847-859. doi: 10.1159/000488742. Epub 2018 Apr 9.
BACKGROUND/AIMS: Metadherin (MTDH) is overexpressed in some malignancies and enhances drug resistance; however, its role in gastric cancer (GC) and the underlying mechanisms remain largely unexplored. Here, we explore the mechanism by which MTDH induces drug resistance in GC.
We analysed the level of MTDH in GC and adjacent normal gastric mucosal tissues by real-time quantitative PCR (q-PCR). We also analysed the level of autophagy by western blot analysis, confocal microscopy, and transmission electron microscopy after MTDH knockdown and overexpression, and examined fluorouracil (5-FU) resistance by Cell Counting Kit-8 at the same time. Finally, GC patient-derived xenograft tumours were used to demonstrate 5-FU resistance. An AMPK pathway inhibitor was applied to determine the molecular mechanisms of autophagy.
MTDH expression was significantly increased in the GC specimens compared with that in the adjacent normal gastric mucosal tissues. Further study showed a positive correlation between the expression level of MTDH and 5-FU resistance. MTDH overexpression in MKN45 cells increased the levels of P-glycoprotein (P-gp) and promoted 5-FU resistance, while inhibition of MTDH showed the opposite result. The simultaneous inhibition of autophagy and overexpression of MTDH decreased the levels of P-gp and inhibited 5-FU resistance. Moreover, MTDH induced AMPK phosphorylation, regulated ATG5 expression, and finally influenced autophagy, suggesting that MTDH may activate autophagy via the AMPK/ATG5 signalling pathway. Our findings reveal a unique mechanism by which MTDH promotes GC chemoresistance and show that MTDH is a potential target for improved chemotherapeutic sensitivity and GC patient survival.
MTDH-stimulated cancer resistance to 5-FU may be mediated through autophagy activated by the AMPK/ATG5 pathway in GC.
背景/目的：Metadherin（MTDH）在某些恶性肿瘤中过表达并增强耐药性；然而，其在胃癌（GC）中的作用及潜在机制仍 largely 未被探索。在此，我们探究 MTDH 在 GC 中诱导耐药性的机制。
我们通过实时定量 PCR（q-PCR）分析 GC 及相邻正常胃黏膜组织中 MTDH 的水平。在 MTDH 敲低和过表达后，我们还通过蛋白质免疫印迹分析、共聚焦显微镜和透射电子显微镜分析自噬水平，并同时使用细胞计数试剂盒-8 检测氟尿嘧啶（5-FU）耐药性。最后，使用 GC 患者来源的异种移植肿瘤来证明 5-FU 耐药性。应用 AMPK 通路抑制剂来确定自噬的分子机制。
与相邻正常胃黏膜组织相比，GC 标本中 MTDH 的表达显著增加。进一步研究表明 MTDH 的表达水平与 5-FU 耐药性呈正相关。MKN45 细胞中 MTDH 的过表达增加了 P-糖蛋白（P-gp）的水平并促进 5-FU 耐药性，而抑制 MTDH 则显示相反的结果。自噬的同时抑制和 MTDH 的过表达降低了 P-gp 的水平并抑制 5-FU 耐药性。此外，MTDH 诱导 AMPK 磷酸化，调节 ATG5 的表达，并最终影响自噬，表明 MTDH 可能通过 AMPK/ATG5 信号通路激活自噬。我们的研究结果揭示了 MTDH 促进 GC 化疗耐药性的独特机制，并表明 MTDH 是提高化疗敏感性和 GC 患者生存率的潜在靶点。
MTDH 刺激的癌症对 5-FU 的耐药性可能通过 GC 中 AMPK/ATG5 途径激活的自噬介导。
