Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Giessen and Marburg, Campus Marburg, D-35037 Marburg, Germany.
Anticancer Res. 2010 Nov;30(11):4579-85.
The anti-apoptotic protein BCL-x(L) and the cell cycle inhibitor p21(CIP1/WAF1) were previously implicated in head and neck cancer. Several reports point to a role of the epidermal growth factor receptor (EGFR, ErbB-1, HER1) in regulating their expression. In the present study, we investigated the influence of EGFR on these tumor-associated factors. HNSCC cell lines were incubated with EGF or with the EGFR-specific kinase inhibitor AG1478. Western blot analysis and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) were deployed to measure BCL-x(L) and p21(CIP1/WAF1) protein and mRNA levels. A dose-dependent rise of BCL-x(L) as well as p21(CIP1/WAF1) protein was noted after incubation with EGF, whereas inhibition with AG1478 reduced basal expression levels. No influence on BCL-2 was seen. Interestingly, qRT-PCR revealed that p21(CIP1/WAF1) but not BCL-x(L) transcript levels were induced after EGF treatment. Taken together, it can be stated that p21(CIP1/WAF1) and BCL-x(L) but not BCL-2 levels are tightly regulated by EGFR in HNSCC cell lines. BCL-x(L) induction appears to be due to protein stabilization rather than transcriptional activation, which is the likely cause of p21(CIP1/WAF1) induction. The noted variability in EGF response of HNSCC cells could reflect frequently observed variations in clinical response rates after implementation of anti-EGFR therapies.
抗凋亡蛋白 BCL-x(L) 和细胞周期抑制剂 p21(CIP1/WAF1) 先前被认为与头颈部癌症有关。有几项报告指出表皮生长因子受体 (EGFR、ErbB-1、HER1) 在调节它们的表达中起作用。在本研究中，我们研究了 EGFR 对这些肿瘤相关因子的影响。用 EGF 或 EGFR 特异性激酶抑制剂 AG1478 孵育 HNSCC 细胞系。采用 Western blot 分析和定量逆转录聚合酶链反应 (qRT-PCR) 来测量 BCL-x(L) 和 p21(CIP1/WAF1) 蛋白和 mRNA 水平。用 EGF 孵育后，观察到 BCL-x(L) 和 p21(CIP1/WAF1) 蛋白呈剂量依赖性增加，而用 AG1478 抑制则降低了基础表达水平。对 BCL-2 没有影响。有趣的是，qRT-PCR 显示，在用 EGF 处理后，p21(CIP1/WAF1) 而不是 BCL-x(L) 的转录本水平被诱导。总之，可以说 p21(CIP1/WAF1) 和 BCL-x(L) 但不是 BCL-2 的水平在 HNSCC 细胞系中受到 EGFR 的严密调节。BCL-x(L) 的诱导似乎是由于蛋白稳定化而不是转录激活，这可能是 p21(CIP1/WAF1) 诱导的原因。HNSCC 细胞对 EGF 反应的显著可变性可能反映了在实施抗 EGFR 治疗后临床反应率经常观察到的变化。
