Substrates and inhibitors of human multidrug resistance associated proteins and the implications in drug development

Human contains 49 ATP-binding cassette (ABC) transporter genes and the multidrug resistance associated proteins (MRP1/ABCC1, MRP2/ABCC2, MRP3/ABCC3, MRP4/ABCC4, MRP5/ABCC5, MRP6/ABCC6, MRP7/ABCC10, MRP8/ABCC11 and MRP9/ABCC12) belong to the ABCC family which contains 13 members. ABCC7 is cystic fibrosis transmembrane conductance regulator; ABCC8 and ABCC9 are the sulfonylurea receptors which constitute the ATP-sensing subunits of a complex potassium channel. MRP10/ABCC13 is clearly a pseudo-gene which encodes a truncated protein that is highly expressed in fetal human liver with the highest similarity to MRP2/ABCC2 but without transporting activity. These transporters are localized to the apical and/or basolateral membrane of the hepatocytes, enterocytes, renal proximal tubule cells and endothelial cells of the blood-brain barrier. MRP/ABCC members transport a structurally diverse array of important endogenous substances and xenobiotics and their metabolites (in particular conjugates) with different substrate specificity and transport kinetics. The human MRP/ABCC transporters except MRP9/ABCC12 are all able to transport organic anions, such as drugs conjugated to glutathione, sulphate or glucuronate. In addition, selected MRP/ABCC members may transport a variety of endogenous compounds, such as leukotriene C(4) (LTC(4) by MRP1/ABCC1), bilirubin glucuronides (MRP2/ABCC2, and MRP3/ABCC3), prostaglandins E1 and E2 (MRP4/ABCC4), cGMP (MRP4/ABCC4, MRP5/ABCC5, and MRP8/ABCC11), and several glucuronosyl-, or sulfatidyl steroids. In vitro, the MRP/ABCC transporters can collectively confer resistance to natural product anticancer drugs and their conjugated metabolites, platinum compounds, folate antimetabolites, nucleoside and nucleotide analogs, arsenical and antimonial oxyanions, peptide-based agents, and in concert with alterations in phase II conjugating or biosynthetic enzymes, classical alkylating agents, alkylating agents. Several MRP/ABCC members (MRPs 1-3) are associated with tumor resistance which is often caused by an increased efflux and decreased intracellular accumulation of natural product anticancer drugs and other anticancer agents. Drug targeting of these transporters to overcome MRP/ABCC-mediated multidrug resistance may play a role in cancer chemotherapy. Most MRP/ABCC transporters are subject to inhibition by a variety of compounds. Based on currently available preclinical and limited clinical data, it can be expected that modulation of MRP members may represent a useful approach in the management of anticancer and antimicrobial drug resistance and possibly of inflammatory diseases and other diseases. A better understanding of their substrates and inhibitors has important implications in development of drugs for treatment of cancer and inflammation.

Receptor mediated tumor targeting : an emerging approach for cancer therapy

Receptor-mediated tumor targeting has received major attention in the field of cancer drug delivery in the past few years. Receptors, as molecular target has opened new opportunities for cellular or intracellular targeting of drug loaded delivery systems conjugated with targeting moieties i.e. ligand. This receptor mediated targeting of cancer drug through nano carrier sys¬tems to cancerous tissue offer protection and improves the pharmacokinetics of various drugs and help to overcome the systemic toxicity and adverse effects that result from the non-selective nature of most current cancer therapeutic agents. The article reviews the scope of receptor mediated targeting of anticancer drug loaded in various nanocarriers and also summarize recent perspective and challenges in the field of nanocarrier-aided drug delivery and drug targeting for cancer therapy.

Synthesis and biological evaluation of novel folic acid receptor-targeted, β-cyclodextrin-based drug complexes for cancer treatment

Drug targeting is an active area of research and nano-scaled drug delivery systems hold tremendous potential for the treatment of neoplasms. In this study, a novel cyclodextrin (CD)-based nanoparticle drug delivery system has been assembled and characterized for the therapy of folate receptor-positive [FR(+)] cancer. Water-soluble folic acid (FA)-conjugated CD carriers (FACDs) were successfully synthesized and their structures were confirmed by 1D/2D nuclear magnetic resonance (NMR), matrix-assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOF-MS), high performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), and circular dichroism. Drug complexes of adamatane (Ada) and cytotoxic doxorubicin (Dox) with FACD were readily obtained by mixed solvent precipitation. The average size of FACD-Ada-Dox was 1.5-2.5 nm. The host-guest association constant Ka was 1,639 M-1 as determined by induced circular dichroism and the hydrophilicity of the FACDs was greatly enhanced compared to unmodified CD. Cellular uptake and FR binding competitive experiments demonstrated an efficient and preferentially targeted delivery of Dox into FR-positive tumor cells and a sustained drug release profile was seen in vitro. The delivery of Dox into FR(+) cancer cells via endocytosis was observed by confocal microscopy and drug uptake of the targeted nanoparticles was 8-fold greater than that of non-targeted drug complexes. Our docking results suggest that FA, FACD and FACD-Ada-Dox could bind human hedgehog interacting protein that contains a FR domain. Mouse cardiomyocytes as well as fibroblast treated with FACD-Ada-Dox had significantly lower levels of reactive oxygen species, with increased content of glutathione and glutathione peroxidase activity, indicating a reduced potential for Dox-induced cardiotoxicity. These results indicate that the targeted drug complex possesses high drug association and sustained drug release properties with good biocompatibility and physiological stability. The novel FA-conjugated β-CD based drug complex might be promising as an anti-tumor treatment for FR(+) cancer.

Identification of unprecedented anticancer properties of high molecular weight biomacromolecular complex containing bovine lactoferrin (HMW-bLf)

With the successful clinical trials, multifunctional glycoprotein bovine lactoferrin is gaining attention as a safe nutraceutical and biologic drug targeting cancer, chronic-inflammatory, viral and microbial diseases. Interestingly, recent findings that human lactoferrin oligomerizes under simulated physiological conditions signify the possible role of oligomerization in the multifunctional activities of lactoferrin molecule during infections and in disease targeting signaling pathways. Here we report the purification and physicochemical characterization of high molecular weight biomacromolecular complex containing bovine lactoferrin (≥250 kDa), from bovine colostrum, a naturally enriched source of lactoferrin. It showed structural similarities to native monomeric iron free (Apo) lactoferrin (∼78-80 kDa), retained anti-bovine lactoferrin antibody specific binding and displayed potential receptor binding properties when tested for cellular internalization. It further displayed higher thermal stability and better resistance to gut enzyme digestion than native bLf monomer. High molecular weight bovine lactoferrin was functionally bioactive and inhibited significantly the cell proliferation (p<0.01) of human breast and colon carcinoma derived cells. It induced significantly higher cancer cell death (apoptosis) and cytotoxicity in a dose-dependent manner in cancer cells than the normal intestinal cells. Upon cellular internalization, it led to the up-regulation of caspase-3 expression and degradation of actin. In order to identify the cutting edge future potential of this bio-macromolecule in medicine over the monomer, its in-depth structural and functional properties need to be investigated further.

Medulloblastoma Down Under 2013 : a report from the third annual meeting of the International Medulloblastoma Working Group.

Medulloblastoma is curable in approximately 70% of patients. Over the past decade, progress in improving survival using conventional therapies has stalled, resulting in reduced quality of life due to treatment-related side effects, which are a major concern in survivors. The vast amount of genomic and molecular data generated over the last 5-10 years encourages optimism that improved risk stratification and new molecular targets will improve outcomes. It is now clear that medulloblastoma is not a single-disease entity, but instead consists of at least four distinct molecular subgroups: WNT/Wingless, Sonic Hedgehog, Group 3, and Group 4. The Medulloblastoma Down Under 2013 meeting, which convened at Bunker Bay, Australia, brought together 50 leading clinicians and scientists. The 2-day agenda included focused sessions on pathology and molecular stratification, genomics and mouse models, high-throughput drug screening, and clinical trial design. The meeting established a global action plan to translate novel biologic insights and drug targeting into treatment regimens to improve outcomes. A consensus was reached in several key areas, with the most important being that a novel classification scheme for medulloblastoma based on the four molecular subgroups, as well as histopathologic features, should be presented for consideration in the upcoming fifth edition of the World Health Organization's classification of tumours of the central nervous system. Three other notable areas of agreement were as follows: (1) to establish a central repository of annotated mouse models that are readily accessible and freely available to the international research community; (2) to institute common eligibility criteria between the Children's Oncology Group and the International Society of Paediatric Oncology Europe and initiate joint or parallel clinical trials; (3) to share preliminary high-throughput screening data across discovery labs to hasten the development of novel therapeutics. Medulloblastoma Down Under 2013 was an effective forum for meaningful discussion, which resulted in enhancing international collaborative clinical and translational research of this rare disease. This template could be applied to other fields to devise global action plans addressing all aspects of a disease, from improved disease classification, treatment stratification, and drug targeting to superior treatment regimens to be assessed in cooperative international clinical trials.

PTEX characterisation and its role in Plasmodium virulence and survival

 Malaria parasites remodel erythrocytes for their survival. They passage proteins into the host cell via an export machinery known as PTEX. For the first time, this study shows that different types of parasite-exported proteins use PTEX. Importantly, new drugs can be developed which target PTEX components to eliminate an infection.

Clinical aspects for survivin: a crucial molecule for targeting drug-resistant cancers

Drug resistance is frequently found in cancer patients who have prolonged chemotherapeutic treatments. Overcoming this phenomenon to make therapy available to these patients is one of the most important features in developing effective cancer therapeutic strategies. Identification of drug resistance causative molecules is one of the most focused areas of cancer research today. Many molecules have been identified in conferring cancer cells the property of drug resistance, and various small molecule inhibitors have been developed to target these molecules to restore the sensitivity of different traditional chemotherapeutic agents, which are frequently found to exhibit reduced potency during prolonged treatment, in cancer patients. Survivin, a member of the inhibitor of apoptosis proteins (IAP) family, has been identified as one of the most crucial biomarkers in the recognition of drug resistance. Survivin is overexpressed in tumor cells, helping in its proliferation and survival, and its overexpression is positively correlated with poor prognosis for cancer patients. Targeted therapeutic measures to inhibit survivin in cancers, particularly drug-resistant tumors, are the recent focus of research for cancer treatment.

Study protocol for a systematic review of evidence for lifestyle interventions targeting smoking, sleep, alcohol/other drug use, physical activity, and healthy diet in people with bipolar disorder

BACKGROUND: People with bipolar disorder (BD) have a mortality gap of up to 20 years compared to the general population. Physical conditions, such as cardiovascular disease (CVD) and cancer, cause the majority of excess deaths in psychiatric populations and are the leading causes of mortality in people with BD. However, comparatively little attention has been paid to reducing the risk of physical conditions in psychiatric populations. Unhealthy lifestyle behaviors are among the potentially modifiable risk factors for a range of commonly comorbid chronic medical conditions, including CVD, diabetes, and obesity. This systematic review will identify and evaluate the available evidence for effective interventions to reduce risk and promote healthy lifestyle behaviors in BD.

METHODS/DESIGN: We will search MEDLINE, Embase, PsychINFO, Cochrane Database of Systematic Reviews, and CINAHL for published research studies (with at least an abstract published in English) that evaluate behavioral or psychosocial interventions to address the following lifestyle factors in people with BD: tobacco use, physical inactivity, unhealthy diet, overweight or obesity, sleep-wake disturbance, and alcohol/other drug use. Primary outcomes for the review will be changes in tobacco use, level of physical activity, diet quality, sleep quality, alcohol use, and illicit drug use. Data on each primary outcome will be synthesized across available studies in that lifestyle area (e.g., tobacco abstinence, cigarettes smoked per day), and panel of research and clinical experts in each of the target lifestyle behaviors and those experienced with clinical and research with individuals with BD will determine how best to represent data related to that primary outcome. Seven members of the systematic review team will extract data, synthesize the evidence, and rate it for quality. Evidence will be synthesized via a narrative description of the behavioral interventions and their effectiveness in improving the healthy lifestyle behaviors in people with BD.

DISCUSSION: The planned review will synthesize and evaluate the available evidence regarding the behavioral or psychosocial treatment of lifestyle-related behaviors in people with BD. From this review, we will identify gaps in our existing knowledge and research evidence about the management of unhealthy lifestyle behaviors in people with BD. We will also identify potential opportunities to address lifestyle behaviors in BD, with a view to reducing the burden of physical ill-health in this population.

What do we know about preventing drug-related harm through social developmental intervention with children and young people

This chapter examines the evidence for the effectiveness of interventions aiming to reduce drug-related harm by improving conditions for healthy develeopment in the earliest years through adolescence. Of the interventions beginning prior to birth, there is efficacy evidence that family home visitation is a feasible strategy for implementation with disadvataged families and can reduce risk factors for early developmental deficits and thereby improve childhood development outcomes. There is efficacy evidence for strategies such as parent education and school preparation through the pre-school age period. Some of the strongest evidence for efficacy in reducing developmental pathways to drug-related harm comes from interventions delivered through the early school years to improve educational environments. Of the interventions targeting the high school age period, school drug education has been the most commonly evaluated. The evidence suggests that short term reduction in both drug use and progression to frequent drug use may be achievable through this strategy, but the prospects for longer-term and population-level behaviour change is still unclear. In overview, a range of prevention strategies have been developed and evaluated. Most of the exisiting evidence is restricted to efficacy studies and there are future challenges to progress evaluation through to studies of effectiveness. In general, prevention programmes appear more successful where they maintain intervention activities over a number of years and incorporate more than one strategy. Much of the existing research has been based in North America and evaluates discrete programmes. Future research should test effects in other countries, in different social contexts and seek to better understand the interrelated effects of combining interventions within the community. Developmental prevention programmes target different age periods and social settings, hence communities have the challenge of coordinating a mixture of programmes that address the local conditions that adversely influence child and youth development. There are opportunities in this work to coordinate prevention activities using funding from different jurisdictions (e.g., crime prevention, health promotion, mental health, education, substance abuse prevention).

A social identity approach to party drug use and associated harm minimisation

This project investigated party (club) drug use and associated harm minimisation strategies of party drug users (N = 72), by gender and sexual
orientation, to determine whether drug use and harm minimisation behaviours differ in particular social groups.Adopting a social identity approach, this project also explored the existence of a party drug user social identity in relation to harmful party drug behaviours and harm minimisation
strategies.Results indicated that males and females showed similar patterns of harmful party drug use and harm minimisation, whilst heterosexuals and homosexuals differed slightly in their patterns of harmful party drug use, and more substantially in their patterns of harm minimisation.Furthermore, results showed some evidence for the existence of a party drug user social identity, which was related to party drug use within a clear social context, and to experiencing fewer party drug related problems.The authors conclude that harm minimisation initiatives need to be designed for particular social groups, such as heterosexuals or homosexuals, targeting their particular patterns of party drug use, and
suggest that effective harm minimisation strategies should incorporate both the social context in which the behaviour occurs, and the social norms of party drug use by particular social groups.

Intracellular drug delivery by sulfatide-mediated liposomes to gliomas

We described here a liposomal carrier system in which the targeting ligand was sulfatide, a glycosphingolipid known to bind several extracellular matrix (ECM) glycoproteins whose expression was highly up-regulated in many tumors. In vitro experiments with human glioma cell lines demonstrated that robust intracellular uptake of the liposomes depended specifically on the presence of sulfatide as the key liposomal component. Significant amount of the liposomes remained largely intact in the cytoplasm for hours following their internalization. When anticancer drug doxorubicin (DOX) was encapsulated in such liposomes, most of the drug was preferably delivered into the cell nuclei to exert its cytotoxicity. Use of this drug delivery system to deliver DOX for treatment of tumor-bearing nude mice displayed much improved therapeutic effects over the free drug or the drug carried by polyethylene glycol (PEG)-grafted liposomes. Our results demonstrate a close link between effective intracellular uptake of the drug delivery system and its therapeutic outcome. Moreover, the sulfatide-containing liposomes (SCL) may represent an interesting ligand-targeted drug carrier for a wide spectrum of cancers in which sulfatide-binding ECM glycoproteins are expressed.

Targeting Hsp90 with small molecule inhibitors induces the over-expression of the anti-apoptotic molecule, survivin, in human A549, HONE-1 and HT-29 cancer cells

Survivin is a dual functioning protein. It inhibits the apoptosis of cancer cells by inhibiting caspases, and also promotes cancer cell growth by stabilizing microtubules during mitosis. Since the molecular chaperone Hsp90 binds and stabilizes survivin, it is widely believed that down-regulation of survivin is one of the important therapeutic functions of Hsp90 inhibitors such as the phase III clinically trialed compound 17-AAG. However, Hsp90 interferes with a number of molecules that up-regulate the intracellular level of survivin, raising the question that clinical use of Hsp90 inhibitors may indirectly induce survivin expression and subsequently enhance cancer anti-drug responses. The purpose of this study is to determine whether targeting Hsp90 can alter survivin expression differently in different cancer cell lines and to explore possible mechanisms that cause the alteration in survivin expression.

Recent advances in nanoneurology for drug delivery to the brain

The drug development for neurodegenerative disorders are the major challenge to the science in 21st century. Many FDA approved drugs currently available in the market have limitations in crossing the blood brain barrier (BBB) owing to its complicated vasculature posed by the presence of specialized cells. Nanotechnology is an emerging interdisciplinary area, which have many applications including drug delivery. Nanocarrier drug delivery involves targeting drugs enclosed in a particular polymer and/or amphiphilic lipids. Controlled release, nanoplatform availability for combinatorial therapy and tissue specific targeting by using advanced technologies such as molecular Trojan horse (MTH) technology are the promises of nanotechnology. Different problems are associated with drug delivery
across the BBB. Some are mostly related to the structure of brain microvasculature system while the others are related to the nanomaterial
structure. Different strategies, such as using polymeric/solid lipid nanoparticles and surface modification of nanomaterial with surfactants
like polysorbates have been conducted to solve these limitations. Also, nanodrug formulations with double coatings have been designed for oral delivery of drugs to overcome reticulo-endothelial system and to improve their BBB permeability. It seems that the best choice of strategy and material could be achieved with regard to the physical and chemical structure of the drugs. The present review discusses the potential applications of nanotechnology for drug delivery across the BBB.

Targeting survivin in cancer : patent review

Importanceof the field: Survivin is a prominent anti-apoptotic molecule expressed widely in the majority of cancers. Overexpression of survivin leads to uncontrolled cancer cell growth and drug resistance. Efficient downregulation of survivin expression and its functions can sensitise the tumour cells to various therapeutic interventions such as chemotherapeutic agents leading to cell apoptosis.

Areas covered in this review: The article thoroughly analyses up-to-date information on the knowledge generated from the survivin patents. Various key areas of research in terms of understanding survivin biology and its targeting are discussed in detail.

What the reader will gain: The article clearly gives an insight on the recent developments undertaken to understand the roles of survivin in cancer and in validating various treatment paradigms that suppress survivin expression in cancer cells.

Take home message:  Most recent developments are helpful for effectively downregulating survivin expression by using various therapeutic platforms such as chemotherapeutic drugs, immunotechnology, antisense, dominant negative survivin mutant, RNA interference and peptide-based methods. However, selective and specific targeting of survivin in cancer cells still poses a major challenge. Nanotechnology-based platforms are currently under development to enable site-specific targeting of survivin in tumour cells.

Contextualising psychological distress among regular ecstasy users : the importance of sociodemographic factors and patterns of drug use

Introduction and Aims. Considerable concern has been raised about associations between ecstasy use and mental health. Studies of ecstasy users typically investigate varying levels of lifetime use of ecstasy, and often fail to account for other drug use and sociodemographic characteristics of participants, which may explain mixed findings. The current study aimed to examine the relationship between patterns of recent (last six months) ecstasy use and psychological distress among current, regular ecstasy users, controlling for sociodemographic risk factors and patterns of other drug use.

Design and Methods. Data were collected from regular ecstasy users (n = 752) recruited from each capital city in Australia as part of the Ecstasy and related Drugs Reporting System (EDRS). Psychological distress was assessed using the Kessler Psychological Distress Scale (K10). Data were analysed using multinomial logistic regression.

Results. Seven per cent of the sample scored in the ‘high’ distress category and 55% in the ‘medium’ distress category. Patterns of ecstasy use were not independently associated with psychological distress. The strongest predictors of distress were female sex, lower education, unemployment, ‘binge’ drug use including ecstasy (use for >48 h without sleep), frequent cannabis use and daily tobacco use.

Discussion and Conclusions. Regular ecstasy users have elevated levels of psychological distress compared with the general population; however, ecstasy use per se was not independently related to such distress. Other factors, including sociodemographic characteristics and other drug use patterns, appear to be more important. These findings highlight the importance of targeting patterns of polydrug use in order to reduce drug-related harm among regular ecstasy users