Understanding the pathways that control epithelial carcinogenesis is vital to the development of effective treatments. The Polycomb group family member Bmi1 is overexpressed in numerous epithelial tumors, but its role in their development has not been established. We now show a key role for Bmi1 in lung adenocarcinoma. Whereas lung development occurs normally in Bmi1-deficient mice, loss of Bmi1 decreases the number and progression of lung tumors at a very early point in an oncogenic K-ras-initiated mouse model of lung cancer. This correlates with a defect in the ability of Bmi1-deficient putative bronchiolalveolar stem cells (BASCs) to proliferate in response to the oncogenic stimulus. Notably, in the absence of oncogenic K-ras, Bmi1-deficient BASCs show impaired proliferation and self-renewal capacity in culture and after lung injury in vivo. Abrogated lung cancer development and BASC self-renewal occur partially in a p19 ARF -dependent manner. Our data suggest that Bmi1 deficiency suppresses tumor development by limiting the expansion potential of BASCs, the apparent lung cancer cells of origin. Because Bmi1 is elevated in additional tumor types, this suggests that Bmi1 plays a key role in regulating proliferation of both stem cells and tumor cells in diverse adult epithelial tissues.Arf ͉ Ink4a ͉ non-small-cell lung cancer ͉ p16

Germ cell tumors (GCTs) affect infants, children and adults and are the most common cancer type in young men. Progress in understanding the molecular basis of germ cell tumors has been hampered by a lack of suitable animal models. Here we report the identification of a zebrafish model of highly penetrant, heritable testicular germ cell tumor isolated as part of a forward-genetic screen for cancer-susceptibility genes. The mutant line develops spontaneous testicular tumors at a median age of 7 months, and pedigree analysis indicates dominant inheritance of the germ cell tumor susceptibility trait. The zebrafish model exhibits disruption of testicular tissue architecture and the accumulation of primitive, spermatogonial-like cells with loss of spermatocytic differentiation. Radiation treatment leads to apoptosis of the tumor cells and tumor regression. The germ cell tumor-susceptible line can serve as a model for understanding the mechanisms regulating germ cells in normal development and disease, and as a platform investigating new therapeutic approaches for germ cell tumors.

Ischemia-reperfusion injury (IRI) is a leading cause of AKI. This common clinical complication lacks effective therapies and can lead to the development of CKD. The v5 integrin may have an important role in acute injury, including septic shock and acute lung injury. To examine its function in AKI, we utilized a specific function-blocking antibody to inhibit v5 in a rat model of renal IRI. Pretreatment with this anti-v5 antibody significantly reduced serum creatinine levels, diminished renal damage detected by histopathologic evaluation, and decreased levels of injury biomarkers. Notably, therapeutic treatment with the v5 antibody 8 hours after IRI also provided protection from injury. Global gene expression profiling of post-ischemic kidneys showed that v5 inhibition affected established injury markers and induced pathway alterations previously shown to be protective. Intravital imaging of post-ischemic kidneys revealed reduced vascular leak with v5 antibody treatment. Immunostaining for v5 in the kidney detected evident expression in perivascular cells, with negligible expression in the endothelium. Studies in a three-dimensional microfluidics system identified a pericyte-dependent role for v5 in modulating vascular leak. Additional studies showed v5 functions in the adhesion and migration of kidney pericytes Initial studies monitoring renal blood flow after IRI did not find significant effects withv5 inhibition; however, future studies should explore the contribution of vasomotor effects. These studies identify a role for v5 in modulating injury-induced renal vascular leak, possibly through effects on pericyte adhesion and migration, and reveal v5 inhibition as a promising therapeutic strategy for AKI.

Tankyrases (TNKS1 and TNKS2) are proteins in the poly ADP-ribose polymerase (PARP) family. They have been shown to directly bind to axin proteins, which negatively regulate the Wnt pathway by promoting β-catenin degradation. Inhibition of tankyrases may offer a novel approach to the treatment of APC-mutant colorectal cancer. Hit compound 8 was identified as an inhibitor of tankyrases through a combination of substructure searching of the Amgen compound collection based on a minimal binding pharmacophore hypothesis and high-throughput screening. Herein we report the structure- and property-based optimization of compound 8 leading to the identification of more potent and selective tankyrase inhibitors 22 and 49 with improved pharmacokinetic properties in rodents, which are well suited as tool compounds for further in vivo validation studies.

Aberrant activation of the Wnt pathway has been implicated in the development and formation of many cancers. TNKS inhibition has been shown to antagonize Wnt signaling via Axin stabilization in APC mutant colon cancer cell lines. We employed structure-based design to identify a series of 2-aminopyridine oxazolidinones as potent and selective TNKS inhibitors. These compounds exhibited good enzyme and cell potency as well as selectivity over other PARP isoforms. Co-crystal structures of these 2-aminopyridine oxazolidinones complexed to TNKS reveal an induced-pocket binding mode that does not involve interactions with the nicotinamide binding pocket. Oral dosing of lead compounds 3 and 4 resulted in significant effects on several Wnt-pathway biomarkers in a three day DLD-1 mouse tumor PD model.