Lai Andrea Z, Cory Sean, Zhao Hong, Gigoux Mathieu, Monast Anie, Guiot Marie-Christine, Huang Sidong, Tofigh Ali, Thompson Crista, Naujokas Monica, Marcus Victoria A, Bertos Nicholas, Sehat Bita, Perera Rushika M, Bell Emily S, Page Brent D G, Gunning Patrick T, Ferri Lorenzo E, Hallett Michael, Park Morag
1Department of Biochemistry, McGill University, Montréal, Québec H3A 0G4, Canada.
Sci Signal. 2014 Apr 22;7(322):ra38. doi: 10.1126/scisignal.2004839.
The Met receptor tyrosine kinase is activated or genetically amplified in some gastric cancers, but resistance to small-molecule inhibitors of Met often emerges in patients. We found that Met abundance correlated with a proliferation marker in patient gastric tumor sections, and gastric cancer cell lines that have MET amplifications depended on Met for proliferation and anchorage-independent growth in culture. Inhibition of Met induced temporal changes in gene expression in the cell lines, initiated by a rapid decrease in the expression of genes encoding transcription factors, followed by those encoding proteins involved in epithelial-mesenchymal transition, and finally those encoding cell cycle-related proteins. In the gastric cancer cell lines, microarray and chromatin immunoprecipitation analysis revealed considerable overlap between genes regulated in response to Met stimulation and those regulated by signal transducer and activator of transcription 3 (STAT3). The activity of STAT3, extracellular signal-regulated kinase (ERK), and the kinase Akt was decreased by Met inhibition, but only inhibitors of STAT3 were as effective as the Met inhibitor in decreasing tumor cell proliferation in culture and in xenografts, suggesting that STAT3 mediates the pro-proliferative program induced by Met. However, the phosphorylation of ERK increased after prolonged Met inhibition in culture, correlating with decreased abundance of the phosphatases DUSP4 and DUSP6, which inhibit ERK. Combined inhibition of Met and the mitogen-activated protein kinase kinase (MEK)-ERK pathway induced greater cell death in cultured gastric cancer cells than did either inhibitor alone. These findings indicate combination therapies that may counteract resistance to Met inhibitors.
在某些胃癌中，Met受体酪氨酸激酶被激活或发生基因扩增，但患者往往会对Met小分子抑制剂产生耐药性。我们发现，在患者胃肿瘤切片中，Met丰度与增殖标志物相关，且具有MET扩增的胃癌细胞系在培养中增殖和非锚定依赖性生长依赖于Met。抑制Met会诱导细胞系中基因表达的时间变化，首先是编码转录因子的基因表达迅速下降，接着是编码参与上皮-间质转化的蛋白质的基因表达下降，最后是编码细胞周期相关蛋白质的基因表达下降。在胃癌细胞系中，微阵列和染色质免疫沉淀分析显示，对Met刺激作出反应而被调控的基因与受信号转导和转录激活因子3（STAT3）调控的基因之间存在相当大的重叠。抑制Met会降低STAT3、细胞外信号调节激酶（ERK）和激酶Akt的活性，但只有STAT3抑制剂在降低培养物和异种移植瘤中的肿瘤细胞增殖方面与Met抑制剂一样有效，这表明STAT3介导了由Met诱导的促增殖程序。然而，在培养中长时间抑制Met后，ERK的磷酸化增加，这与抑制ERK的磷酸酶DUSP4和DUSP6丰度降低相关。联合抑制Met和丝裂原活化蛋白激酶激酶（MEK）-ERK途径在培养的胃癌细胞中比单独使用任何一种抑制剂诱导的细胞死亡都更多。这些发现表明了可能对抗Met抑制剂耐药性的联合疗法。
