Matheny Keith E, Barbieri Christopher E, Sniezek Joseph C, Arteaga Carlos L, Pietenpol Jennifer A
Vanderbilt Bill Wilkerson Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
Laryngoscope. 2003 Jun;113(6):936-9. doi: 10.1097/00005537-200306000-00004.
OBJECTIVES/HYPOTHESIS: Both the epidermal growth factor receptor (EGFR) and the p53 homologue p63 are overexpressed in a significant number of cases of head and neck squamous cell carcinoma (HNSCC). Epidermal growth factor receptor and p63 both possess oncogenic properties, including the potential to increase cell proliferation and antagonize apoptosis. ZD1839 ("Iressa") is an adenosine triphosphate-competitive inhibitor specific to the EGFR tyrosine kinase currently under evaluation as a chemotherapeutic agent in HNSCC. The objective was to investigate whether p63 expression is decreased after treatment of HNSCC cells with ZD1839. Downregulation of p63 by ZD1839 would identify a potential molecular relationship between EGFR signaling and p63 and could provide insight into the mechanism of action of ZD1839.
In vitro examination of p63 expression after ZD1839 treatment.
A human HNSCC cell line, SCC-012, was treated with varying doses of ZD1839. p63 protein and messenger RNA levels were analyzed by Western and Northern blot analyses. The effect of ZD1839 on SCC-012 cell cycle was analyzed by flow cytometric analysis.
In SCC-012 cells there was a dose-dependent decrease in p63 protein and messenger RNA levels over the course of ZD1839 treatment. Levels of phosphorylated MAPK decreased and p27KIP-1 levels increased after ZD1839 treatment. ZD1839 treatment induced a twofold increase in G1-phase cells and a 3.5-fold decrease in S-phase cells consistent with growth arrest.
ZD1839 downregulates p63 expression at the messenger RNA level, suggesting that p63 is a downstream target of EGFR signaling.
目的/假设：表皮生长因子受体（EGFR）和p53同源物p63在大量头颈部鳞状细胞癌（HNSCC）病例中均有过表达。表皮生长因子受体和p63都具有致癌特性，包括增加细胞增殖和拮抗细胞凋亡的潜力。ZD1839（“易瑞沙”）是一种对EGFR酪氨酸激酶具有特异性的三磷酸腺苷竞争性抑制剂，目前正作为HNSCC的化疗药物进行评估。目的是研究用ZD1839处理HNSCC细胞后p63表达是否降低。ZD1839对p63的下调将确定EGFR信号传导与p63之间潜在的分子关系，并可为ZD1839的作用机制提供见解。
对ZD1839处理后的p63表达进行体外检测。
用人HNSCC细胞系SCC - 012用不同剂量的ZD1839处理。通过蛋白质免疫印迹法和Northern印迹法分析p63蛋白和信使RNA水平。通过流式细胞术分析ZD1839对SCC - 012细胞周期的影响。
在SCC - 012细胞中，在ZD1839处理过程中p63蛋白和信使RNA水平呈剂量依赖性降低。ZD1839处理后磷酸化MAPK水平降低，p27KIP - 1水平升高。ZD1839处理导致G1期细胞增加两倍，S期细胞减少3.5倍，与生长停滞一致。
ZD1839在信使RNA水平下调p63表达，表明p63是EGFR信号传导的下游靶点。
