Targeting integrin α6 stimulates curative-type bone metastasis lesions in a xenograft model

Terry H. Landowski, Jaime Gard, Erika Pond, Gerald D. Pond, Raymond B. Nagle, Christopher P. Geffre, Anne E. Cress

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Abstract

Laminin-binding integrin receptors are key mediators of epithelial cell migration and tumor metastasis. Recent studies have demonstrated a role for the α6 integrin (ITGA6/CD49f) in maintaining stem cell compartments within normal bone marrow and in residency of tumors metastatic to bone. In this study, we tested a function-blocking antibody specific for ITGA6, called J8H, to determine if preexisting cancer lesions in bone could be slowed and/or animal survival improved. Human prostate tumors were established by intracardiac injection into male SCID mice and treatment with J8H antibody was initiated after 1 week. Tumor progression was monitored by micro-computed tomography (CT) imaging of skeletal lesions. Animals that received weekly injections of the anti-ITGA6 antibody showed radiographic progression in only 40% of osseous tumors (femur or tibia), compared with control animals, where 80% of the lesions (femur or tibia) showed progression at 5 weeks. Kaplan-Meier survival analysis demonstrated a significant survival advantage for J8H-treated animals. Unexpectedly, CT image analysis revealed an increased proportion of bone lesions displaying a sclerotic rim of new bone formation, encapsulating the arrested lytic lesions in animals that received the anti-ITGA6 antibody treatment. Histopathology of the sclerotic lesions demonstrated wellcircumscribed tumor within bone, surrounded by fibrosis. These data suggest that systemic targeting of the ITGA6-dependent function of established tumors in bone may offer a noncytotoxic approach to arrest the osteolytic progression of metastatic prostate cancer, thereby providing anewtherapeutic strategy for advanced disease.

Original languageEnglish (US)
Pages (from-to)1558-1566
Number of pages9
JournalMolecular Cancer Therapeutics
Volume13
Issue number6
DOIs
StatePublished - Jun 2014

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ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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