Summary Despite success with BRAFV600E–inhibitors, therapeutic responses in patients with metastatic melanoma are short-lived because of the acquisition of drug resistance. We identified a mechanism of intrinsic multi-drug resistance based on the survival of a tumor cell subpopulation. Treatment with various drugs, including cisplatin and vemurafenib, uniformly leads to enrichment of slow-cycling, long-term tumor-maintaining melanoma cells expressing the H3K4-demethylase JARID1B/KDM5B/PLU-1. Proteome-profiling revealed an upregulation in enzymes of mitochondrial oxidative-ATP-synthesis (OXPHOS) in this subpopulation. Inhibition of mitochondrial respiration blocked the emergence of the JARID1Bhigh subpopulation and sensitized melanoma cells to therapy, independent of their genotype. Our findings support a two-tiered approach combining anti-cancer agents that eliminate rapidly proliferating melanoma cells with inhibitors of the drug-resistant slow-cycling subpopulation.

The use of nanotechnology for drug delivery has shown great promise for improving cancer treatment. However, potential toxicity, hazardous environmental effects, issues with large-scale production, and potential excessive costs are challenges that confront their further clinical applications. Here, we describe a nanovector made from ginger-derived lipids that can serve as a delivery platform for the therapeutic agent doxorubicin (Dox) to treat colon cancer. We created nanoparticles from ginger and reassembled their lipids into ginger-derived nanovectors (GDNVs). A subsequent characterization showed that GDNVs were efficiently taken up by colon cancer cells. Viability and apoptosis assays and electric cell-substrate impedance-sensing technology revealed that GDNVs exhibited excellent biocompatibility up to 200 μmol/l; by contrast, cationic liposomes at the same concentrations decreased cell proliferation and increased apoptosis. GDNVs were capable of loading Dox with high efficiency and showed a better pH-dependent drug-release profile than commercially available liposomal-Dox. Modified GDNVs conjugated with the targeting ligand folic acid mediated targeted delivery of Dox to Colon-26 tumors in vivo and enhanced the chemotherapeutic inhibition of tumor growth compared with free drug. Current experiments explore the feasibility of producing nature-derived nanoparticles that are effective as a treatment vehicle while potentially attenuating the issues related to traditional synthetic nanoparticles.

Recently we demonstrated that PLC⑀ plays an important role in ␤-adrenergic receptor (␤AR) stimulation of Ca 2؉-induced Ca 2؉ release (CICR) in cardiac myocytes. Here we have reported for the first time that a pathway downstream of ␤AR involving the cAMPdependent Rap GTP exchange factor, Epac, and PLC⑀ regulates CICR in cardiac myocytes. To demonstrate a role for Epac in the stimulation of CICR, cardiac myocytes were treated with an Epacselective cAMP analog, 8-4-(chlorophenylthio)-2-O-methyladenosine-3,5-monophosphate (cpTOME). cpTOME treatment increased the amplitude of electrically evoked Ca 2؉ transients, implicating Epac for the first time in cardiac CICR. This response is abolished in PLC⑀ ؊/؊ cardiac myocytes but rescued by transduction with PLC⑀, indicating that Epac is upstream of PLC⑀. Furthermore, transduction of PLC⑀ ؉/؉ cardiac myocytes with a Rap inhibitor, RapGAP1, significantly inhibited isoproterenol-dependent CICR. Using a combination of cpTOME and PKA-selective activators and inhibitors, we have shown that ␤AR-dependent increases in CICR consist of two independent components mediated by PKA and the novel Epac/PLC⑀ pathway. We also show that Epac/PLC⑀-dependent effects on CICR are independent of sarcoplasmic reticulum loading and Ca 2؉ clearance mechanisms. These data define a novel endogenous PKA-independent ␤AR-signaling pathway through cAMP-dependent Epac activation, Rap, and PLC⑀ that enhances intracellular Ca 2؉ release in cardiac myocytes.Stimulation of adrenergic receptors by either neurohumoral or systemic release of the catecholamines epinephrine and norepinephrine produces acute increases in cardiac contractility during stress and exercise to increase cardiac output and oxygen delivery to tissues. Much of the increase in cardiac output is due to the direct stimulation of the ␤ adrenergic receptor (␤AR) 2 in cardiac myocytes (1, 2). Activation of ␤AR activates G s and adenylyl cyclase resulting in the production of cAMP and subsequent activation of protein kinase A, which phosphorylates key components of the calcium handling and contractile machinery.Analysis of a phospholipase C (PLC)⑀ knock-out mouse model (PLC⑀ Ϫ/Ϫ ) generated in our laboratory indicates that PLC⑀ contributes to ␤AR-dependent regulation of cardiac function (3). PLC⑀ Ϫ/Ϫ mice exhibit significantly decreased left ventricular developed pressure in response to acute stimulation with the ␤AR agonist, isoproterenol. Isolated myocytes from PLC⑀ Ϫ/Ϫ mice exhibit decreased isoproterenol-dependent enhancement of electrically evoked Ca 2ϩ release in the absence of effects on ␤AR density or cAMP generation. These data implicate PLC⑀ as a novel component of ␤AR regulation of Ca 2ϩ release, which had not previously been described in the heart. However, the pathway linking ␤AR stimulation to PLC⑀ activation is unknown.PLC-mediated phosphatidyl-4,5-bisphosphate hydrolysis resulting in intracellular Ca 2ϩ release and protein kinase C activation is an integral signaling component of many physiological processes in a variety of tissu...

Kynurenine pathway (KP) is the primary path of tryptophan (Trp) catabolism in most mammalian cells. The KP generates several bioactive catabolites, such as kynurenine (Kyn), kynurenic acid (KA), 3-hydroxykynurenine (3-HK), xanthurenic acid (XA), and 3-hydroxyanthranilic acid (3-HAA). Increased catabolite concentrations in serum are associated with several cardiovascular diseases (CVD), including heart disease, atherosclerosis, and endothelial dysfunction, as well as their risk factors, including hypertension, diabetes, obesity, and aging. The first catabolic step in KP is primarily controlled by indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO). Following this first step, the KP has two major branches, one branch is mediated by kynurenine 3-monooxygenase (KMO) and kynureninase (KYNU) and is responsible for the formation of 3-HK, 3-HAA, and quinolinic acid (QA); and another branch is controlled by kynurenine aminotransferase (KAT), which generates KA. Uncontrolled Trp catabolism has been demonstrated in distinct CVD, thus, understanding the underlying mechanisms by which regulates KP enzyme expression and activity is paramount. This review highlights the recent advances on the effect of KP enzyme expression and activity in different tissues on the pathological mechanisms of specific CVD, KP is an inflammatory sensor and modulator in the cardiovascular system, and KP catabolites act as the potential biomarkers for CVD initiation and progression. Moreover, the biochemical features of critical KP enzymes and principles of enzyme inhibitor development are briefly summarized, as well as the therapeutic potential of KP-enzyme inhibitors against CVD is briefly discussed.

Progression of liver fibrosis requires sustained inflammation leading to hepatocytes apoptosis through ER stress, whereas associated with activation of hepatic stellate cells (HSCs) into a fibrogenic and proliferative cell type. Faced with persistent and massive ER stress, HSCs adaptation starts to fail and apoptosis occurs in reversal of liver fibrosis, possibly mediated through calcium perturbations, unfolded protein response, and the pro-apoptotic transcription factor CHOP. Although limited in scope, current studies underscored that ER stress is tightly linked to adaptation, inflammation and apoptosis, and recent evidences suggested that these processes are related to the pathogenesis of liver fibrosis and its recovery.