Endoplasmic Reticulum Stress-Induced JNK Activation Is a Critical Event Leading to Mitochondria-Mediated Cell Death Caused by β-Lapachone Treatment

β-lapachone (β-lap) is a bioreductive agent that is activated by the two-electron reductase NAD(P)H quinone oxidoreductase 1 (NQO1). Although β-lap has been reported to induce apoptosis in various cancer types in an NQO1-dependent manner, the signaling pathways by which β-lap causes apoptosis are poorly understood.β-lap-induced apoptosis and related molecular signaling pathways in NQO1-negative and NQO1-overexpressing MDA-MB-231 cells were investigated. Pharmacological inhibitors or siRNAs against factors involved in β-lap-induced apoptosis were used to clarify the roles played by such factors in β-lap-activated apoptotic signaling pathways. β-lap leads to clonogenic cell death and apoptosis in an NQO1- dependent manner. Treatment of NQO1-overexpressing MDA-MB-231 cells with β-lap causes rapid disruption of mitochondrial membrane potential, nuclear translocation of AIF and Endo G from mitochondria, and subsequent caspase-independent apoptotic cell death. siRNAs targeting AIF and Endo G effectively attenuate β-lap-induced clonogenic and apoptotic cell death. Moreover, β-lap induces cleavage of Bax, which accumulates in mitochondria, coinciding with the observed changes in mitochondria membrane potential. Pretreatment with Salubrinal (Sal), an endoplasmic reticulum (ER) stress inhibitor, efficiently attenuates JNK activation caused by β-lap, and subsequent mitochondria-mediated cell death. In addition, β-lap-induced generation and mitochondrial translocation of cleaved Bax are efficiently blocked by JNK inhibition.Our results indicate that β-lap triggers induction of endoplasmic reticulum (ER) stress, thereby leading to JNK activation and mitochondria-mediated apoptosis. The signaling pathways that we revealed in this study may significantly contribute to an improvement of NQO1-directed tumor therapies

State of Land in the Mekong Region

The Mekong region is in the midst of profound social and environmental change. Despite rapid urbanization, the region remains predominantly rural with more than 60 percent of its population living in rural areas, the vast majority of whom are engaged in agriculture. This population not only continues to grow, but is also disproportionately poor and reliant on land and forest resources. Due to the rapid growth of its agricultural sector, the Mekong region has become a global centre of production and trade for commodities such as rubber, rice, cassava, wood, sugar cane and oil palm. While accelerated flows of global investment and the trade of land-intensive commodities have contributed to growing GDP and the enrichment of some societal actors, outcomes have been highly unequal. The benefits of development have largely accrued to the urban elite, while costs have largely been borne by the rural poor, transforming rural land relations and presenting new insecurities for land tenure. The Mekong region may be at a tipping-point, and transformational change is imperative to sustainably address the needs of agricultural smallholders. Data and information are urgently needed to understand these changes, to inform more equitable and innovative decision-making, and to monitor the outcomes of these decisions. The State of Land in the Mekong Region thus brings together key data and information on current status and trajectories of change with regard to land resources, their social distribution, and the conditions of governance that shape them.1s

An NQO1- and PARP-1-mediated cell death pathway induced in non-small-cell lung cancer cells by β-lapachone

Lung cancer is the number one cause of cancer-related deaths in the world. Patients treated with current chemotherapies for non-small-cell lung cancers (NSCLCs) have a survival rate of ≈15% after 5 years. Novel approaches are needed to treat this disease. We show elevated NAD(P)H:quinone oxidoreductase-1 (NQO1) levels in tumors from NSCLC patients. β-Lapachone, an effective chemotherapeutic and radiosensitizing agent, selectively killed NSCLC cells that expressed high levels of NQO1. Isogenic H596 NSCLC cells that lacked or expressed NQO1 along with A549 NSCLC cells treated with or without dicoumarol, were used to elucidate the mechanism of action and optimal therapeutic window of β-lapachone. NSCLC cells were killed in an NQO1-dependent manner by β-lapachone (LD50, ≈4 μM) with a minimum 2-h exposure. Kinetically, β-lapachone-induced cell death was characterized by the following: (i) dramatic reactive oxygen species (ROS) formation, eliciting extensive DNA damage; (ii) hyperactivation of poly(ADP-ribose)polymerase-1 (PARP-1); (iii) depletion of NAD+/ATP levels; and (iv) proteolytic cleavage of p53/PARP-1, indicating μ-calpain activation and apoptosis. β-Lapachone-induced PARP-1 hyperactivation, nucleotide depletion, and apoptosis were blocked by 3-aminobenzamide, a PARP-1 inhibitor, and 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid acetoxymethyl ester (BAPTA-AM), a Ca2+ chelator. NQO1− cells (H596, IMR-90) or dicoumarol-exposed NQO1+ A549 cells were resistant (LD50, >40 μM) to ROS formation and all cytotoxic effects of β-lapachone. Our data indicate that the most efficacious strategy using β-lapachone in chemotherapy was to deliver the drug in short pulses, greatly reducing cytotoxicity to NQO1− “normal” cells. β-Lapachone killed cells in a tumorselective manner and is indicated for use against NQO1+ NSCLC cancers