旁路信号通路激活介导的EML4-ALK融合基因阳性肺癌细胞株H3122对alectinib继发耐药的研究

目的:本研究旨在探讨肝细胞生长因子(HGF)、表皮生长因子(EGF)及转化生长因子α(TGF-α)是否以旁路激活的方式诱导EML4-ALK融合基因阳性肺癌细胞株H3122对alectinib的耐药,并进一步探讨旁路信号激活在alectinib耐药中的作用。方法:用不同浓度的alectinib、克唑替尼(crizotinib)、17-DMAG或(和)HGF(50μg/L)、EGF(100μg/L)、TGF-α(100μg/L)处理EML4-ALK阳性肺癌细胞株H3122,采用CCK-8法检测细胞活力,流式细胞术检测细胞凋亡,应用Western blot技术检测细胞中ALK、c-Met、EGFR及相应磷酸化蛋白的表达,观察其下游通路关键蛋白AKT、ERK、p-AKT和p-ERK水平。结果:Alectinib作用72 h后,H3122细胞株的活力随着alectinib药物浓度的增加而逐渐下降,呈剂量依赖性。HGF、EGF和TGF-α诱导后,alectinib抑制H3122细胞的生长曲线往右移,HGF、EGF和TGF-α处理能够降低alectinib对肺癌细胞活力的抑制作用。0.05μmol/L alectinib作用H3122细胞株48 h后的凋亡率为(20.12±1.36)%,而alectinib联合HGF、EGF和TGF-α后的凋亡率分别为(7.85±1.03)%、(5.60±0.79)%和(4.58±1.00)%,显著低于alectinib单药处理(P0.05)。Alectinib单药成功抑制p-ALK及其下游信号通路,HGF明显增加细胞中p-Met及其下游p-AKT、p-ERK的蛋白水平,EGF和TGF-α明显增加细胞中p-EGFR及其下游p-AKT、p-ERK的表达,alectinib抑制p-ALK,但不能抑制HGF、EGF和TGF-α诱导的pAKT和p-ERK的蛋白表达。此外,联合应用crizotinib和17-DMAG可以抑制因HGF和EGFR配体而导致的H3122耐药细胞的活力。结论:HGF、EGF和TGF-α可通过旁路激活的方式诱导EML4-ALK阳性肺癌细胞H3122对alectinib耐药,其机制可能与HGF激活c-Met磷酸化、EGF和TGF-α激活EGFR磷酸化有关。

Bypass signaling pathway activation mediates resistance of EML4-ALK fusion gene positive lung cancer cell line H3122 to alectinib

AIM: To detect the changes of active status of bypass signaling pathways in EML4-ALK positive lung cancer cell line H3122 treated with alectinib, hepatocyte growth factor (HGF), epidermal growth factor (EGF) and transforming growth factor-α (TGF-α), and to explore the potential mechanisms.METHODS: EML4-ALK positive cell line H3122 was treated with increasing concentrations of alectinib or/and induced by HGF, EGF and TGF-α. The cell viability was measured by CCK-8 assay. The cell apoptosis was analyzed by flow cytometry. The protein levels and phosphorylation status of ALK, c-Met and EGFR, and the downstream molecules AKT, ERK, p-AKT and p-ERK were examined by Western blot.RESULTS: The viability of the H3122 cells was inhibited by alectinib in a dose-dependent manner after administrated for 72 h, and the IC₅₀ value was 0.042 μmol/L. The concentration-growth curves of the H3122 cells shifted to the right after induced by HGF, EGF and TGF-α. After treatment with alectinib at 0.05 μmol/L for 48 h, the apoptotic rate of H3122 cells was (20.12±1.36)%, while the apoptotic rates of the cells in the groups of alectinib combined with HGF, EGF or TGF-α were (7.85±1.03)%, (5.60±0.79)% and (4.58±1.00)%, respectively. Those values were remarkably lower than those in alectinib single treatment group (P<0.05). Alectinib inhibited the protein levels of p-ALK and its downstream signaling pathway molecules, while HGF significantly up-regulated the protein levels of p-Met and its downstream p-AKT and p-ERK. Besides, EGF and TGF-α remarkablely up-regulated the protein levels of p-EGFR and its downstream p-AKT and p-ERK. Combined treatment with crizotinib and 17-DMAG successfully inhibited the viability of the H3122 cells even in the presence of the HGF and EGFR ligands, respectively.CONCLUSION: Bypass signaling pathways are activated by HGF, EGF and TGF-α in EML4-ALK positive lung cancer cell line H3122, which may be linked to alectinib resistance.