Chemotherapy resistance is a major obstacle in cancer treatment, yet the mechanisms of response to specific therapies have been largely unexplored in vivo. Employing genetic, genomic, and imaging approaches, we examined the dynamics of response to a mainstay chemotherapeutic, cisplatin, in multiple mouse models of human non-small-cell lung cancer (NSCLC). We show that lung tumors initially respond to cisplatin by sensing DNA damage, undergoing cell cycle arrest, and inducing apoptosis-leading to a significant reduction in tumor burden. Importantly, we demonstrate that this response does not depend on the tumor suppressor p53 or its transcriptional target, p21. Prolonged cisplatin treatment promotes the emergence of resistant tumors with enhanced repair capacity that are cross-resistant to platinum analogs, exhibit advanced histopathology, and possess an increased frequency of genomic alterations. Cisplatin-resistant tumors express elevated levels of multiple DNA damage repair and cell cycle arrest-related genes, including p53-inducible protein with a death domain (Pidd). We demonstrate a novel role for PIDD as a regulator of chemotherapy response in human lung tumor cells.[Keywords: Mouse models; cisplatin; Kras; p53; chemotherapy resistance; lung cancer] Supplemental material is available at http://www.genesdev.org.

Background: Cardiac angina is the hallmark of myocardial ischemia, but the role of the cardiac sensory nerve has received relatively little attention. Recently, both acid-sensing ion channel 3 (ASIC3) and capsaicin receptor (TRPV1) have been suggested as important mediators in sensing myocardial ischemia. However, studies comparing the physiological roles of ASIC3 and TRPV1 in the neuronal - cardiac sensing circuits in vivo are lacking. Methods and Results:Isoproterenol (1.5 mg/kg, intraperitoneally) was used to induce transient myocardial ischemia in Asic3 +/+ and Asic3 -/-mice and a radio-telemetry system was used for electrocardiography with mice in a conscious state. Isoproterenol-induced myocardial ischemia was first demonstrated with ST-segment depression and further confirmed by hypoxia-mediated chemical reactions in cardiac tissue. Mice lacking Asic3 showed prolonged duration of ST-segment depression compared with Asic3 +/+ mice (44.3±3.1 vs. 31.7±2.9 min; P<0.05). Although ischemia was transient, severe cardiac fibrosis was found in Asic3 -/-but not in Asic3 +/+ mice littermates. In contrast, isoproterenol-injected Trpv1 +/+ and Trpv1 -/-mice showed no difference in duration of ST-segment depression and, surprisingly, deletion of Trpv1 did not aggravate cardiac fibrosis.Conclusions: An isoproterenol-induced myocardial ischemia model mimicking clinical conditions of early cardiac angina was used to demonstrate that ASIC3 but not TRPV1 plays a protective role in sensing myocardial ischemia. (Circ J 2011; 75: 174 - 178)

The conserved multi-protein MuvB core associates with the Myb oncoproteins and with the RB-E2F-DP tumor suppressor proteins in complexes that regulate cell proliferation, differentiation, and apoptosis. Drosophila Mip120, a homolog of LIN54, is a sequence-specific DNA-binding protein within the MuvB core. A mutant of Drosophila mip120 was previously shown to cause female and male sterility. We now show that Mip120 regulates two different aspects of oogenesis. First, in the absence of the Mip120 protein, egg chambers arrest during the transition from stage 7 to 8 with a failure of the normal program of chromosomal dynamics in the ovarian nurse cells. Specifically, the decondensation, disassembly and dispersion of the endoreplicated polytene chromosomes fail to occur without Mip120. The conserved carboxy-terminal DNA-binding and protein-protein interaction domains of Mip120 are necessary but not sufficient for this process. Second, we show that a lack of Mip120 causes a dramatic increase in the expression of benign gonial cell neoplasm (bgcn), a gene that is normally expressed in only a small number of cells within the ovary including the germline stem cells.