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Drug resistant

Vasanthanathan Poongavanam, Jacob Kongsted
The high rate of drug resistance as well as the complex biochemical process of the parasite reproduction cycle makes development of new drugs for malaria a very important but challenging task. Falcipain 2 (FL2) and Falcipain 3 (FL3) are the major cysteine protease enzymes that play a central role in providing essential amino acids for the parasite's protein biosynthesis through the hemoglobin hydrolysis process. Selective inhibition of these enzymes is considered as a promising chemotherapeutic target. In the present investigation, the highly efficient linear interaction energy (LIE) method has been parameterized for binding affinity predictions and assessed with a set of 244 compounds for FL2 and FL3 inhibition...
June 26, 2016: Journal of Molecular Graphics & Modelling
Daniel Nichol, Mark Robertson-Tessi, Peter Jeavons, Alexander R A Anderson
Non-genetic variation in phenotypes, or bet-hedging, has been observed as a driver of drug resistance in both bacterial infections and cancers. Here, we study how bet-hedging emerges in the genotype-phenotype mapping through a simple interaction model: a molecular switch. We use simple Chemical Reaction Networks to implement stochastic switches that map gene products to phenotypes and investigate the impact of structurally distinct mappings on the evolution of phenotypic heterogeneity. Bet-hedging naturally emerges within this model and is robust to evolutionary loss through mutations to both the expression of individual genes and to the network itself...
October 21, 2016: Genetics
Phei Er Saw, Jinho Park, Sangyong Jon, Omid C Farokhzad
A major problem with cancer chemotherapy begins when cells acquire resistance. Drug-resistant cancer cells typically upregulate multi-drug resistance proteins such as P-glycoprotein (P-gp). However, the lack of overexpressed surface biomarkers has limited the targeted therapy of drug-resistant cancers. Here we report a drug-delivery carrier decorated with a targeting ligand for a surface marker protein Extra-domain B(EDB) specific to drug-resistant breast cancer cells as a new therapeutic option for the aggressive cancers...
October 18, 2016: Nanomedicine: Nanotechnology, Biology, and Medicine
Raghavendra Gowda, Arati Sharma, Gavin P Robertson
Melanoma is a highly drug resistant cancer. To circumvent this problem, a class of synergistically acting drug combinations, which inhibit multiple key pathways in melanoma cells, could be used as one approach for long-term treatment of this deadly disease. A screen has been undertaken on cell lines to identify those that could be combined to synergistically kill melanoma cells. Plumbagin and Celecoxib are two agents that were identified to synergistically kill melanoma cells by inhibiting the COX-2 and STAT3 pathways, which are constitutively activated in up to 70% of melanomas...
October 18, 2016: Cancer Letters
Chao-Ming Hung, Ying-Chao Lin, Liang-Chih Liu, Sheng-Chu Kuo, Chi-Tang Ho, Tzong-Der Way
CWF-145, a synthetic 2-phenyl-4-quinolone derivative exerted potent cytotoxicity against prostate cancer. CWF-145 inhibited prostate cancer cell lines PC-3, DU-145 and LNCap. It had a very low IC50 about 200 nM against castrate-resistant prostate cancer (CRPC) PC-3. We found that CWF-145 had a similar effect to clinical trial antimitotic agents in cancer cells and normal cells. CWF-145 arrested cell cycle at G2/M phase by binding to the β-tubulin at the colchicine-binding site then disrupted microtubule polymerization...
October 18, 2016: Chemico-biological Interactions
Sanjib K Shrestha, Liliia M Kril, Keith D Green, Stefan Kwiatkowski, Vitaliy M Sviripa, Justin R Nickell, Linda P Dwoskin, David S Watt, Sylvie Garneau-Tsodikova
The emergence of multidrug-resistant bacterial and fungal strains poses a threat to human health that requires the design and synthesis of new classes of antimicrobial agents. We evaluated bis(N-amidinohydrazones) and N-(amidino)-N'-aryl-bishydrazones for their antibacterial and antifungal activities against panels of Gram-positive/Gram-negative bacteria as well as fungi. We investigated their potential to develop resistance against both bacteria and fungi by a multi-step resistance-selection method, explored their potential to induce the production of reactive oxygen species, and assessed their toxicity...
October 10, 2016: Bioorganic & Medicinal Chemistry
Ester Fernandez-Salas, Shaomeng Wang, Arul M Chinnaiyan
Castration resistant prostate cancer (CRPC) is a deadly disease with few therapeutic options once patients become resistant to second generation drugs targeting the AR-transcriptional program. The BET-BRD readers of chromatin are key regulators of AR-, ERG-, and c-Myc-mediated transcription in CRPC. BET-BRD inhibitors have demonstrated pre-clinical efficacy in models of CRPC and are currently being evaluated in several clinical trials. These novel drugs have the potential to transform the way we treat CRPC in the near future...
March 2016: Drug Discovery Today. Technologies
Cheng-Ming Chiang
BRD4 is an epigenetic regulator and transcription cofactor whose phosphorylation by CK2 and dephosphorylation by PP2A modulates its function in chromatin targeting, factor recruitment, and cancer progression. While the bromodomains of BET family proteins, including BRD4, BRD2, BRD3 and BRDT, have been the primary targets of small compounds such as JQ1, I-BET and MS417 that show promising anticancer effects against some hematopoietic cancer and solid tumors, drug resistance upon prolonged treatment necessitates a better understanding of alternative pathways underlying not only the resistance but also persistent BET protein dependence for identifying new targets and effective combination therapy strategies...
March 2016: Drug Discovery Today. Technologies
Suwanna Chaorattanakawee, Chanthap Lon, Krisada Jongsakul, Jariyanart Gawee, Somethy Sok, Siratchana Sundrakes, Nareth Kong, Chatchadaporn Thamnurak, Soklyda Chann, Sorayut Chattrakarn, Chantida Praditpol, Nillawan Buathong, Nichapat Uthaimongkol, Philip Smith, Narongrid Sirisopana, Rekol Huy, Satharath Prom, Mark M Fukuda, Delia Bethell, Douglas S Walsh, Charlotte Lanteri, David Saunders
BACKGROUND: The recent dramatic decline in dihydroartemisinin-piperaquine (DHA-PPQ) efficacy in northwestern Cambodia has raised concerns about the rapid spread of piperaquine resistance just as DHA-PPQ is being introduced as first-line therapy in neighbouring countries. METHODS: Ex vivo parasite susceptibilities were tracked to determine the rate of progression of DHA, PPQ and mefloquine (MQ) resistance from sentinel sites on the Thai-Cambodian and Thai-Myanmar borders from 2010 to 2015...
October 21, 2016: Malaria Journal
Alfred Amambua-Ngwa, Bakary Danso, Archibald Worwui, Sukai Ceesay, Nwakanma Davies, David Jeffries, Umberto D'Alessandro, David Conway
BACKGROUND: Previous genome-wide analyses of single nucleotide variation in Plasmodium falciparum identified evidence of an extended haplotype region on chromosome 6 in West Africa, suggesting recent positive selection. Such a pattern is not seen in samples from East Africa or South East Asia, so it could be marking a selective process specific to West Africa. Analyses of the haplotype structure in samples taken at different times could give clues to possible causes of selection. METHODS: This study investigates chromosome 6 extended haplotypes in The Gambia by analysing alleles at multiple microsatellite loci using genome sequence data previously obtained from clinical isolates collected in 2008, followed by genotyping of 13 loci in 439 isolates from 1984, 1991, 2008 and 2014...
October 21, 2016: Malaria Journal
Tshifhiwa Magoro, George Gachara, Lufuno Mavhandu, Emmaculate Lum, Helen K Kimbi, Roland N Ndip, Pascal Bessong
BACKGROUND: HBV and HIV share similar transmission routes. Concurrent infection with the two viruses usually results in more severe and progressive liver disease, and a higher incidence of cirrhosis, liver cancer and mortality. Further, this co-infection may lead to cross-resistance between HIV and HBV drugs and increased liver injury, either due to direct hepatotoxicity or drug-related immune-reconstitution hepatitis. These challenges necessitate continuous surveillance for HBV among HIV infected individuals to guide patient management...
October 21, 2016: Virology Journal
Shanshan Wang, Yinjuan Guo, Jingnan Lv, Xiuqin Qi, Dan Li, Zengqiang Chen, Xueqing Zhang, Liangxing Wang, Fangyou Yu
BACKGROUND: Quinupristin/dalfopristin (Q/D) is a valuable alternative antibiotic to vancomycin for the treatment of multi-drug resistant Enterococcus faecium infections. However, resistance to Q/D in E. faecium clinical isolates and nosocomial dissemination of Q/D-resistant E. faecium have been reported in several countries and should be of concern. RESULTS: From January 2012 to December 2015, 911 E. faecium clinical isolates were isolated from various specimens of inpatients at the first Affiliated Hospital of Wenzhou Medical University located in Wenzhou, east China...
October 21, 2016: BMC Microbiology
Kathryn Schnippel, Rebecca H Berhanu, Andrew Black, Cynthia Firnhaber, Norah Maitisa, Denise Evans, Edina Sinanovic
BACKGROUND: According to the World Health Organization, South Africa ranks as one of the highest burden of TB, TB/HIV co-infection, and drug-resistant TB (DR-TB) countries. DR-TB treatment is complicated to administer and relies on the use of multiple toxic drugs, with potential for severe adverse drug reactions. We report the occurrence of adverse events (AEs) during a standardised DR-TB treatment regimen at two outpatient, decentralized, public-sector sites in Johannesburg, South Africa...
October 21, 2016: BMC Infectious Diseases
Pierre Dehoux, Jean Christophe Marvaud, Amr Abouelleil, Ashlee M Earl, Thierry Lambert, Catherine Dauga
BACKGROUND: Clostridium bolteae and Clostridium clostridioforme, previously included in the complex C. clostridioforme in the group Clostridium XIVa, remain difficult to distinguish by phenotypic methods. These bacteria, prevailing in the human intestinal microbiota, are opportunistic pathogens with various drug susceptibility patterns. In order to better characterize the two species and to obtain information on their antibiotic resistance genes, we analyzed the genomes of six strains of C...
October 21, 2016: BMC Genomics
Hongfang Zhang, Conghua Xie, Jing Yue, Zhenzhen Jiang, Rongjing Zhou, Ruifei Xie, Yan Wang, Shixiu Wu
Previous studies on the mechanisms underlying ESCC (esophageal squamous cell carcinoma) chemoresistance only focused on tumor cells while tumor microenvironment has been completely ignored. Our study aimed to clarify the effect of CAFs (cancer-associated fibroblasts), one major component of tumor microenvironment, on the chemoresistance of ESCC. By primary culture, two pairs of CAFs and matched NFs (normal fibroblasts) were isolated from tumor tissues of ESCC patients and matched normal esophageal epithelial tissues, respectively...
October 21, 2016: Molecular Carcinogenesis
Massimo Nabissi, Maria Beatrice Morelli, Massimo Offidani, Consuelo Amantini, Silvia Gentili, Alessandra Soriani, Claudio Cardinali, Pietro Leoni, Giorgio Santoni
Several studies showed a potential anti-tumor role for cannabinoids, by modulating cell signaling pathways involved in cancer cell proliferation, chemo-resistance and migration. Cannabidiol (CBD) was previously noted in multiple myeloma (MM), both alone and in synergy with the proteasome inhibitor bortezomib, to induce cell death. In other type of human cancers, the combination of CBD with Δ9-tetrahydrocannabinol (THC) was found to act synergistically with other chemotherapeutic drugs suggesting their use in combination therapy...
October 18, 2016: Oncotarget
Troy A Skwor, Stephanie Klemm, Hanyu Zhang, Brianna Schardt, Stephanie Blaszczyk, Matthew A Bork
Increasing rates of antibiotic resistance coupled with the lack of novel antibiotics threatens proper clinical treatment and jeopardizes their use in prevention. A photodynamic approach appears to be an innovative treatment option, even for multi-drug resistant strains of bacteria. Three components are utilized in photodynamic inactivation: a photosensitizer, light source, and oxygen. Variations in photosensitizers strongly influence microbial binding and bactericidal activity. In this study, four different cationic metalloporphyrins (Cu(2+), Fe(2+), Pd(2+), Zn(2+)) were compared to the free-base ligand 5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin regarding their electronic properties and generation of reactive oxygen species upon subsequent 405nm violet-blue irradiation...
October 15, 2016: Journal of Photochemistry and Photobiology. B, Biology
Xiang-Xin Huang, Yun-Xuan Li, Xiang-Yu Li, Xiao-Xia Hu, Peng-Fei Tang, Guo-Xin Hu
Currently, crizotinib is the first generation drug, which has been used in the treatment of ALK-rearranged non-small cell lung cancer (NSCLC). However, more and more patients are found in crizotinib-resistance. In the last year, alectinib has been approved for treatment of patients with crizotinib-resistance. In this study, we aim to develop and validate a simple, rapid and sensitive tandem mass spectrometry (UHPLC-MS/MS) method for determination of alectinib in rat plasma. Diazepam was chosen as an internal standard (IS)...
October 14, 2016: Journal of Pharmaceutical and Biomedical Analysis
Cong Wu, Meng-Qing Gong, Bo-Ya Liu, Ren-Xi Zhuo, Si-Xue Cheng
To effectively reverse multiple drug resistance (MDR) in tumor treatments, a functional nano-sized drug delivery system with active targeting function and pH sensitivity was prepared for the co-delivery of multiple drug resistance inhibitors. Buthionine sulfoximine (BSO) to inhibit GSH synthesis and celecoxib (CXB) to down-regulate P-gp expression were co-loaded in polymer/inorganic hybrid nanoparticles to form buthionine sulfoximine/celecoxib@biotin-heparin/heparin/calcium carbonate/calcium phosphate nanoparticles (BSO/CXB@BNP)...
October 13, 2016: Colloids and Surfaces. B, Biointerfaces
Kristina R Kesely, Antonella Pantaleo, Francesco M Turrini, Peter Olupot-Olupot, Philip S Low
With half of the world's population at risk for malaria infection and with drug resistance on the rise, the search for mutation-resistant therapies has intensified. We report here a therapy for Plasmodium falciparum malaria that acts by inhibiting the phosphorylation of erythrocyte membrane band 3 by an erythrocyte tyrosine kinase. Because tyrosine phosphorylation of band 3 causes a destabilization of the erythrocyte membrane required for parasite egress, inhibition of the erythrocyte tyrosine kinase leads to parasite entrapment and termination of the infection...
2016: PloS One
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