Lorch G, Gilmore J L, Koltz P F, Gonterman R M, Laughner R, Lewis D A, Konger R L, Nadella K S, Toribio R E, Rosol T J, Foley J
Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210, USA.
Br J Cancer. 2007 Jul 16;97(2):183-93. doi: 10.1038/sj.bjc.6603828. Epub 2007 May 29.
The purpose of this study was to evaluate the role of the epidermal growth factor receptor (EGFR) in parathyroid hormone-related protein (PTHrP) expression and humoral hypercalcaemia of malignancy (HHM), using two different human squamous-cell carcinoma (SCC) xenograft models. A randomised controlled study in which nude mice with RWGT2 and HARA xenografts received either placebo or gefitinib 200 mg kg(-1) for 3 days after developing HHM. Effectiveness of therapy was evaluated by measuring plasma calcium and PTHrP, urine cyclic AMP/creatinine ratios, and tumour volumes. The study end point was at 78 h. The lung SCC lines, RWGT2 and HARA, expressed high levels of PTHrP mRNA as well as abundant EGFR protein, but very little erbB2 or erbB3. Both lines expressed high transcript levels for the EGFR ligand, amphiregulin (AREG), as well as, substantially lower levels of transforming growth factor-alpha (TGF-alpha), and heparin binding-epidermal growth factor (HB-EGF) mRNA. Parathyroid hormone-related protein gene expression in both lines was reduced 40-80% after treatment with 1 muM of EGFR tyrosine kinase inhibitor PD153035 and precipitating antibodies to AREG. Gefitinib treatment of hypercalcaemic mice with RWGT2 and HARA xenografts resulted in a significant reduction of plasma total calcium concentrations by 78 h. Autocrine AREG stimulated the EGFR and increased PTHrP gene expression in the RWGT2 and HARA lung SCC lines. Inhibition of the EGFR pathway in two human SCC models of HHM by an anilinoquinazoline demonstrated that the EGFR tyrosine kinase is a potential target for antihypercalcaemic therapy.
本研究旨在利用两种不同的人鳞状细胞癌（SCC）异种移植模型，评估表皮生长因子受体（EGFR）在甲状旁腺激素相关蛋白（PTHrP）表达及恶性肿瘤体液性高钙血症（HHM）中的作用。一项随机对照研究，将接种了RWGT2和HARA异种移植物的裸鼠在发生HHM后，给予安慰剂或200 mg kg(-1)吉非替尼，持续3天。通过测量血浆钙和PTHrP、尿环磷酸腺苷/肌酐比值以及肿瘤体积来评估治疗效果。研究终点为78小时。肺SCC细胞系RWGT2和HARA表达高水平的PTHrP mRNA以及丰富的EGFR蛋白，但erbB2或erbB3表达极少。两种细胞系均高表达EGFR配体双调蛋白（AREG）的转录水平，同时，转化生长因子-α（TGF-α）和肝素结合表皮生长因子（HB-EGF）mRNA的水平显著较低。用1 μM的EGFR酪氨酸激酶抑制剂PD153035和AREG沉淀抗体处理后，两种细胞系中的甲状旁腺激素相关蛋白基因表达降低了40 - 80%。用吉非替尼治疗接种了RWGT2和HARA异种移植物的高钙血症小鼠，78小时后血浆总钙浓度显著降低。自分泌AREG刺激EGFR并增加RWGT2和HARA肺SCC细胞系中的PTHrP基因表达。在两种HHM的人SCC模型中，用苯胺喹唑啉抑制EGFR途径表明，EGFR酪氨酸激酶是抗高钙血症治疗的潜在靶点。
