Nakagawa Motomichi, Nabeshima Kazuki, Asano Shigeyuki, Hamasaki Makoto, Uesugi Noriko, Tani Hiroki, Yamashita Yuichi, Iwasaki Hiroshi
Department of Pathology, Fukuoka University Hospital and School of Medicine, Fukuoka 814-0180, Japan.
Cancer Sci. 2009 Apr;100(4):654-62. doi: 10.1111/j.1349-7006.2009.01089.x. Epub 2009 Mar 1.
Metalloproteinase activities of a disintegrin and metalloproteinases (ADAMs), matrix metalloproteinases (MMPs), and membrane type (MT-)MMPs are involved in many aspects of tumor biology. ADAMs are transmembrane proteins that cleave membrane-anchored proteins to release soluble factors, and thereby mediate important biological phenomena in tumors. The aim of this study was to analyze histopathology, expression and roles of metalloproteinases, especially ADAMs, in gastric gastrointestinal stromal tumor (GIST). Histopathology and immunohistochemical expression of ADAMs were examined in 89 gastric GISTs. In 11 GISTs, ADAM expression was examined at mRNA and protein levels by reverse transcription-polymerase chain reaction (RT-PCR) and immunoblotting, respectively. RT-PCR analysis showed frequent expression of ADAM9 (91%), ADAM10 (64%), ADAM17 (82%), MMP-2 (82%), and MT1-MMP (73%). However, ADAM17 and MMP-2 were the only metalloproteinases that were up-regulated in GISTs at the protein level compared with non-neoplastic gastric tissues. ADAM17 was immunohistochemically expressed in 93% of GIST versus 16% of normal gastric tissues. Furthermore, CD117-positive interstitial cells of Cajal in normal gastric tissues were all negative for ADAM17 with double immunostaining. Expressions of epidermal growth factor receptor (EGFR) and several EGFR ligands such as amphiregulin, heparin-binding epidermal growth factor (HB-EGF), betacellulin, and epiregulin were also demonstrated in GIST by RT-PCR. Protein expression of EGFR, phosphorylated EGFR, amphiregulin, and HB-EGF, both of which can be shed by ADAM17, was confirmed in tumors coexpressing ADAM17 by immunoblotting. Moreover, proteolytically cleaved soluble forms of amphiregulin were identified in tumor extracts. Considered together, the results suggest that ADAM17 may contribute to the progression and growth of GIST through shedding of EGFR ligands and consequent EGFR stimulation. ADAM17, as a major sheddase in GIST, could be potentially a suitable target in anticancer treatment of imatinib-resistant GISTs.
解整合素金属蛋白酶（ADAMs）、基质金属蛋白酶（MMPs）和膜型（MT-）MMPs的金属蛋白酶活性参与肿瘤生物学的多个方面。ADAMs是跨膜蛋白，可切割膜锚定蛋白以释放可溶性因子，从而介导肿瘤中的重要生物学现象。本研究旨在分析金属蛋白酶，尤其是ADAMs在胃胃肠道间质瘤（GIST）中的组织病理学、表达及作用。对89例胃GIST进行了ADAMs的组织病理学和免疫组化表达检测。在11例GIST中，分别通过逆转录-聚合酶链反应（RT-PCR）和免疫印迹法在mRNA和蛋白水平检测了ADAM的表达。RT-PCR分析显示ADAM9（91%）、ADAM10（64%）、ADAM17（82%）、MMP-2（82%）和MT1-MMP（73%）频繁表达。然而，与非肿瘤性胃组织相比，ADAM17和MMP-2是GIST中仅在蛋白水平上调的金属蛋白酶。ADAM17在93%的GIST中免疫组化表达，而在正常胃组织中为16%。此外，通过双重免疫染色，正常胃组织中CD117阳性的 Cajal间质细胞ADAM17均为阴性。RT-PCR还证实了GIST中表皮生长因子受体（EGFR）及几种EGFR配体如双调蛋白、肝素结合表皮生长因子（HB-EGF）、β细胞素和表皮调节素的表达。通过免疫印迹法在共表达ADAM17的肿瘤中证实了EGFR、磷酸化EGFR、双调蛋白和HB-EGF的蛋白表达，二者均可被ADAM17裂解。此外，在肿瘤提取物中鉴定出了经蛋白水解切割的可溶性双调蛋白形式。综合来看，结果表明ADAM17可能通过裂解EGFR配体并随后刺激EGFR，促进GIST的进展和生长。ADAM17作为GIST中的主要裂解酶，可能是伊马替尼耐药GIST抗癌治疗的合适靶点。
