Attempt to Tumor Dormancy Therapy for Pancreatic Cancer -Purification of the Novel Angiogenesis Inhibitor from Pancreatic Carcinoma Cell Lines-

Shinya Onizuka, Oliver Kisker^*, Steven Pirie-Shepherd^*, Judah Folkman^* and Takashi Kanematsu

Department of Surgery II, Nagasaki University School of Medicine ^*Department of Surgery, Children's Hospitl, Harvard Medical School

Tumor growth in cancers is angiogenesis-dependent. Angiogenesis inhibitors induce tumor dormancy by increasing apoptosis. Tumor dormancy therapy may be useful in pancreatic cancer because new therapeutic strategies are required in this malignant tumor, which has a dismal prognosis. We demonstrated that the human pancreatic carcinoma cell line, BxPC-3 generates an angiogenesis inhibitor, latent and cleaved forms of antithrombin III (antiangiogenic antithrombin III, aaAT-III), that regress tumor growth in severe combined immunodeficiency disease (SCID) mice. Conditioned BxPC-3 medium was applied to heparin-sepharose affinity and gel filtration high-pressure liquid chromatography (HPLC). Fractions eluted from this chromatography showed 58 kDa and 53 kDa bands on SDS-PAGE. Microsequencing identified latent and cleaved antithrombin III, both of which inhibited bovine capillary endothelial (BCE) cell proliferation ; native AT-III had no such effect. This demonstrates that conformational change in AT-III results in a new function as an angiogenesis inhibitor. Human recombinant aaAT-III was obtained in the same purification step using the conditioned BxPC-3 medium cultured with human AT-III. It inhibited tumor growth of BxPC-3, maintaining tumor dormancy during 21 days of treatment. Antiangiogenic therapy using aaAT-III may thus have clinical application as tumor dormancy therapy for pancreatic cancer in the near future.

Key words
pancreatic cancer, angiogenesis, tumor dormancy

Reprint requests
Shinya Onizuka Department of Surgery II, Nagasaki University School of Medicine 1-7-1 Sakamoto, Nagasaki, 852-8501 JAPAN

Accepted
December 19, 2000

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