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Research Articles

Platelet-derived growth factor receptor-: a novel therapeutic target in human hepatocellular cancer

Departments of ¹ Pathology and ² Medicine (Gastroenterology), University of Pittsburgh School of Medicine and ³ Department of Human Oncology, Allegheny General Hospital, Pittsburgh, Pennsylvania and ⁴ ImClone Systems, Inc., New York, New York

Requests for reprints: Satdarshan P.S. Monga, Department of Pathology, University of Pittsburgh School of Medicine, 200 Lothrop Street, S421-BST Pittsburgh, PA 15213. Phone: 412-648-8146; Fax: 412-648-1916. E-mail: smonga{at}pitt.edu

Abstract

Hepatocellular cancer (HCC) is a disease of poor prognosis. Identifying novel molecular aberrations might present opportunities to identify new therapeutic targets. Due to the similarities between the processes of development and cancer, we used early developing livers to identify genes that might play a primary role in HCC. Platelet-derived growth factor receptor- (PDGFR) was identified from microarray using early developing mouse livers. Expression of PDGFR and its upstream effectors, PDGF-AA and PDGF-CC, were examined in HCC tissues (n = 43) by Western blot, real-time PCR, and immunohistochemistry. Finally, effect of anti-PDGFR antibody (mAb 3G3, ImClone Systems, Inc.) was examined on human hepatoma cells. A high expression of PDGFR was observed during early liver development. HCCs (17 of 21) revealed cytoplasmic PDGFR and activated PDGFR (phospho-Tyr⁷⁵⁴) by immunohistochemistry. Additional HCCs (14 of 22) showed elevated PDGFR levels when compared with the adjacent normal livers by Western blots. Of these 14 patients, 3 showed increased PDGFR gene expression, 3 showed elevated PDGF-AA, and 4 had higher PDGF-CC levels in the tumors compared with adjacent livers. Multiple hepatoma cell lines, when treated with mAb 3G3, showed significant decreases in cell proliferation and survival (P < 0.05). In conclusion, 70% of HCC tissues had elevated PDGFR levels due to diverse mechanisms. PDGFR inhibition in hepatoma cells led to diminution of tumor cell survival and proliferation and thus might be of therapeutic significance. [Mol Cancer Ther 2007;6(7):1932–41]

Grant support: American Cancer Society grant RSG-03-141-01-CNE and NIH grant 1RO1DK62277 (S.P.S. Monga). Cleveland Foundation and Rango's Fund for Enhancement of Pathology Research.

Note: P. Stock and D. Monga contributed equally to this work.

The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

⁵ Supplementary material for this article is available at Molecular Cancer Therapeutics Online (http://mct.aacrjournals.org/).

Received 11/21/06; revised 4/24/07; accepted 5/29/07.