Abstract

The collagen IV binding receptor integrin otiol has been shown to regulate lung cancer due to its proangiogenic properties; however, it is unclear whether this receptor also plays a direct role in promoting primary lung tumors. To investigate this possibility, integrin ctl-null mice were crossed with KrasLA2 mice that carry an oncogenic mutation of the Kras gene (GI2D) and develop spontaneous primary tumors with features of non-small cell lung cancer. We provide evidence that KrasLA2/ocl -null mice have a decreased incidence of primary lung tumors and longer survival compared with KrasLA2/cxl wild-type controls. Tumors from KrasLA2/(xl -null mice were also smaller, less vascularized, and exhibited reduced cell proliferation and increased apoptosis, as determined by proliferating cell nuclear antigen and terminal deoxynucleotidyl-transferase-mediated dUTP nick-end staining, respectively. Moreover, tumors from the KrasLA2/otl-null mice showed diminished extracellular signal-regulated kinase (ERK) but enhanced p38 mitogenactivated protein kinase activation. Primary lung tumor epithelial cells isolated from KrasLA2/otl-null mice showed a significant decrease in anchorage -independent colony formation, collagen-mediated cell proliferation, ERK activation, and, most importantly, tumorigenicity when injected into nude mice compared with KrasLA2/oJ wild-type tumor cells. These results indicate that loss of the integrin od subunit decreases the incidence and growth of lung epithelial tumors initiated by oncogenic Kras, suggesting that both Kras and integrin cx 10 1 cooperate to drive the growth of non-small cell lung cancer in vivo.