Liu Phillip C C, Liu Xiangdong, Li Yanlong, Covington Maryanne, Wynn Richard, Huber Reid, Hillman Milton, Yang Gengjie, Ellis Dawn, Marando Cindy, Katiyar Kamna, Bradley Jodi, Abremski Kenneth, Stow Mark, Rupar Mark, Zhuo Jincong, Li Yun-Long, Lin Qiyan, Burns David, Xu Meizhong, Zhang Colin, Qian Ding-Quan, He Chunhong, Sharief Vaqar, Weng Lingkai, Agrios Costas, Shi Eric, Metcalf Brian, Newton Robert, Friedman Steven, Yao Wenqing, Scherle Peggy, Hollis Gregory, Burn Timothy C
Drug Discovery, Incyte Corporation, Experimental Station, Wilmington, Delaware 19880, USA.
Cancer Biol Ther. 2006 Jun;5(6):657-64. doi: 10.4161/cbt.5.6.2708. Epub 2006 Jun 14.
Overexpression and activating mutations of ErbB family members have been implicated in the development and progression of a variety of tumor types. Cleavage of the HER2 receptor by an as yet unidentified ectodomain sheddase has been shown to liberate the HER2 extracellular domain (ECD) leaving a fragment with constitutive kinase activity that can provide ligand-independent growth and survival signals to the cell. This process is clinically relevant since HER2 ECD serum levels in metastatic breast cancer patients are associated with a poorer prognosis. Thus, inhibition of the HER2 sheddase may provide a novel therapeutic approach for breast cancer. We describe the use of transcriptional profiling, pharmacological and in vitro approaches to identify the major source of HER2 sheddase activity. Real-time PCR was used to identify those ADAM family members which were expressed in HER2 shedding cell lines. siRNAs that selectively inhibited ADAM10 expression reduced HER2 shedding. In addition, we profiled over 1000 small molecules for in vitro inhibition of a panel of ADAM and MMP proteins; a positive correlation was observed only between ADAM10 inhibition and reduction of HER2 ECD shedding in a cell based assay. Finally, in vitro studies demonstrate that in combination with low doses of Herceptin, selective ADAM10 inhibitors decrease proliferation in HER2 overexpressing cell lines while inhibitors, that do not inhibit ADAM10, have no impact. These results are consistent with ADAM10 being a major determinant of HER2 shedding, the inhibition of which, may provide a novel therapeutic approach for treating a variety of cancers with active HER2 signaling.
ErbB家族成员的过表达和激活突变与多种肿瘤类型的发生和发展有关。一种尚未明确的胞外域裂解酶对HER2受体的切割已被证明能释放HER2细胞外结构域（ECD），留下一个具有组成性激酶活性的片段，该片段可向细胞提供不依赖配体的生长和存活信号。这一过程具有临床相关性，因为转移性乳腺癌患者的HER2 ECD血清水平与较差的预后相关。因此，抑制HER2裂解酶可能为乳腺癌提供一种新的治疗方法。我们描述了使用转录谱分析、药理学和体外方法来确定HER2裂解酶活性的主要来源。实时PCR用于鉴定在HER2脱落细胞系中表达的ADAM家族成员。选择性抑制ADAM10表达的小干扰RNA（siRNA）可减少HER2的脱落。此外，我们对1000多种小分子进行了体外抑制一组ADAM和基质金属蛋白酶（MMP）蛋白的分析；在基于细胞的分析中，仅观察到ADAM10抑制与HER2 ECD脱落减少之间存在正相关。最后，体外研究表明，与低剂量赫赛汀联合使用时，选择性ADAM10抑制剂可降低HER2过表达细胞系的增殖，而不抑制ADAM10的抑制剂则无此作用。这些结果与ADAM10是HER2脱落的主要决定因素一致，抑制ADAM10可能为治疗具有活跃HER2信号的多种癌症提供一种新的治疗方法。
