Ho Ruth, Minturn Jane E, Hishiki Tomoro, Zhao Huaqing, Wang Qun, Cnaan Avital, Maris John, Evans Audrey E, Brodeur Garrett M
Division of Oncology, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania 19104-4318, USA.
Cancer Res. 2005 Nov 1;65(21):9868-75. doi: 10.1158/0008-5472.CAN-04-2426.
Neuroblastoma is a common solid tumor of childhood that is derived from the neural crest. Expression of epidermal growth factor (EGF) receptors (EGFRs) has been associated with enhanced cell growth and aggressive behavior in other tumors. Here, we examined the expression profile of EGFRs in neuroblastoma cell lines and primary tumors. We found that all 13 neuroblastoma cell lines examined expressed EGFR1 (HER1), most at readily detectable levels. Low levels of other human EGFR family receptors were also detected in almost all cell lines. All primary tumors examined expressed readily detectable levels of HER1 and HER3 and lower levels of HER2 and HER4. EGF had a significant effect on the proliferation of neuroblastoma cell lines in vitro. EGF treatment (100 ng/mL) of the cell lines SY5Y and NLF significantly increased cell number (P < 0.01). EGF stimulated more cells to enter S and G2-M phase, as suggested by flow cytometry, indicating that EGF increases cell number by increasing proliferation, with no appreciable change in apoptosis. EGF exposure resulted in receptor autophosphorylation and activation of both the mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/AKT pathways. Exposure to 0.5 micromol/L ZD1839, a HER1-specific inhibitor, caused a 40% to 50% reduction in the number of SY5Y and NLF cells grown in medium containing 10% fetal bovine serum (P < 0.01). Even at 0.01 micromol/L, ZD1839 inhibited autophosphorylation of HER1 by EGF. At 0.1 micromol/L, it also blocked phosphorylation of AKT, but not MAPK, in NLF cells. Additional studies showed that the PI3K/AKT-specific inhibitor LY294002 had a more profound effect than the MAPK-specific inhibitor U0126 in blocking EGF-induced cell proliferation. This suggests that the PI3K/AKT pathway is the main signaling pathway responsible for the proliferation effects of EGF in neuroblastomas. Our results also indicate that ZD1839 is a potent inhibitor of neuroblastoma cell proliferation; therefore, it may be a useful, biologically based therapeutic agent for these tumors.
神经母细胞瘤是一种常见的儿童实体瘤，起源于神经嵴。表皮生长因子（EGF）受体（EGFRs）的表达与其他肿瘤中细胞生长增强和侵袭性行为有关。在此，我们检测了神经母细胞瘤细胞系和原发性肿瘤中EGFRs的表达谱。我们发现，所检测的13种神经母细胞瘤细胞系均表达EGFR1（HER1），大多数表达水平易于检测。几乎所有细胞系中也检测到低水平的其他人类EGFR家族受体。所检测的所有原发性肿瘤均表达易于检测水平的HER1和HER3，以及较低水平的HER2和HER4。EGF对神经母细胞瘤细胞系的体外增殖有显著影响。用EGF（100 ng/mL）处理细胞系SY5Y和NLF可显著增加细胞数量（P < 0.01）。流式细胞术结果表明，EGF刺激更多细胞进入S期和G2-M期，这表明EGF通过增加增殖来增加细胞数量，而凋亡无明显变化。EGF暴露导致受体自磷酸化，并激活丝裂原活化蛋白激酶（MAPK）和磷脂酰肌醇3激酶（PI3K）/AKT途径。用HER1特异性抑制剂ZD1839（0.5 μmol/L）处理后，在含有10%胎牛血清的培养基中生长的SY5Y和NLF细胞数量减少了40%至50%（P < 0.01）。即使在0.01 μmol/L时，ZD1839也能抑制EGF诱导的HER1自磷酸化。在0.1 μmol/L时，它还能阻断NLF细胞中AKT的磷酸化，但不能阻断MAPK的磷酸化。进一步的研究表明，PI3K/AKT特异性抑制剂LY294002在阻断EGF诱导的细胞增殖方面比MAPK特异性抑制剂U0126具有更显著的作用。这表明PI3K/AKT途径是负责EGF在神经母细胞瘤中增殖作用的主要信号通路。我们的结果还表明，ZD1839是神经母细胞瘤细胞增殖的有效抑制剂；因此，它可能是一种对这些肿瘤有用的、基于生物学的治疗药物。
