title: Targeting constitutively activated β1 integrins inhibits prostate cancer metastasis.
abstract: Disseminated prostate cancer cells must survive in circulation for metastasis to occur. Mechanisms by which these cells survive are not well understood. By immunohistochemistry of human tissues, we found that levels of β1 integrins and integrin-induced autophosphorylation of FAK (pFAK-Y397) are increased in prostate cancer cells in primary prostate cancer and lymph node metastases, suggesting that β1 integrin activation occurs in metastatic progression of prostate cancer. A conformation-sensitive antibody, 9EG7, was used to examine β1 integrin activation. We found that β1 integrins are constitutively activated in highly metastatic PC3 and PC3-mm2 cells, with less activation in low metastatic LNCaP and C4-2B4 cells. Increased β1 integrin activation as well as the anoikis resistance in prostate cancer cells correlated with metastatic potential in vivo. Knockdown of β1 integrin abrogated anoikis resistance in PC3-mm2 cells. In agreement with β1 integrin activation, PC3-mm2 cells strongly adhered to type I collagen and fibronectin, a process inhibited by the β1 integrin-neutralizing antibody mAb 33B6. mAb 33B6 also inhibited the phosphorylation of β1 integrin downstream effectors, focal adhesion kinase (FAK) and AKT, leading to a 3-fold increase in PC3-mm2 apoptosis. Systemic delivery of mAb 33B6 suppressed spontaneous metastasis of PC3-mm2 from the prostate to distant lymph nodes following intraprostatic injection and suppressed metastasis of PC3-mm2 to multiple organs following intracardiac injection. Thus, constitutively activated β1 integrins play a role in survival of PC3-mm2 cells in circulation and represent a potential target for metastasis prevention.
authors: Department of Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
authors: Yu-Chen
authors: YC
authors: Lee
authors: Jung-Kang
authors: JK
authors: Jin
authors: Chien-Jui
authors: CJ
authors: Cheng
authors: Chih-Fen
authors: CF
authors: Huang
authors: Jian H
authors: JH
authors: Song
authors: Miao
authors: M
authors: Huang
authors: Wells S
authors: WS
authors: Brown
authors: Sui
authors: S
authors: Zhang
authors: Li-Yuan
authors: LY
authors: Yu-Lee
authors: Edward T
authors: ET
authors: Yeh
authors: Bradley W
authors: BW
authors: McIntyre
authors: Christopher J
authors: CJ
authors: Logothetis
authors: Gary E
authors: GE
authors: Gallick
authors: Sue-Hwa
authors: SH
authors: Lin
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D045744:Cell Line, Tumor; D005109:Extracellular Matrix; D006801:Humans; D007150:Immunohistochemistry; D019012:Integrin beta1 / Q000276:immunology / Q000378:metabolism*; D008207:Lymphatic Metastasis; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009362:Neoplasm Metastasis; D010766:Phosphorylation; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000473:pathology*; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D019012:Integrin beta1