Search results for " Drug Resistance"

HER2 Signaling and Breast Cancer Stem Cells: The Bridge behind HER2-Positive Breast Cancer Aggressiveness and Therapy Refractoriness

2021

Simple Summary Breast cancer (BC) is not a single disease, but a group of different tumors, and altered HER2 expression defines a particularly aggressive subtype. Although HER2 pharmacological inhibition has dramatically improved the prognosis of HER2-positive BC patients, there is still an urgent need for improved knowledge of HER2 biology and mechanisms underlying HER2-driven aggressiveness and drug susceptibility. Emerging data suggest that the clinical efficacy of molecularly targeted therapies is related to their ability to target breast cancer stem cells (BCSCs), a population that is not only self-sustaining and able to differentiate into distinct lineages, but also contributes to tum…

Dual Inhibition of Myc Transcription and PI3K Activity Effectively Targets Colorectal Cancer Stem Cells

2022

Despite advances in the curative approach, the survival rate of advanced colorectal cancer (CRC) patients is still poor, which is likely due to the emergence of cancer cell clones resistant to the available therapeutic options. We have already shown that CD44v6-positive CRC stem cells (CR-CSCs) are refractory toward standard anti-tumor therapeutic agents due to the activation of the PI3K pathway together with high HER2 expression levels. Tumor microenvironmental cytokines confer resistance to CR-CSCs against HER2/PI3K targeting by enhancing activation of the MAPK pathway. Here, we show that the CSC compartment, spared by BRAF inhibitor-based targeted therapy, is associated with increased ex…

MicroRNA-29b-1 impairs in vitro cell proliferation, self‑renewal and chemoresistance of human osteosarcoma 3AB-OS cancer stem cells

2014

Osteosarcoma (OS) is the most common type of bone cancer, with a peak incidence in the early childhood. Emerging evidence suggests that treatments targeting cancer stem cells (CSCs) within a tumor can halt cancer and improve patient survival. MicroRNAs (miRNAs) have been implicated in the maintenance of the CSC phenotype, thus, identification of CSC-related miRNAs would provide information for a better understanding of CSCs. Downregulation of miRNA-29 family members (miR-29a/b/c; miR‑29s) was observed in human OS, however, little is known about the functions of miR-29s in human OS CSCs. Previously, during the characterization of 3AB-OS cells, a CSC line selected from human OS MG63 cells, we…

In Vitro Modulation of P-Glycoprotein Activity by Euphorbia intisy Essential Oil on Acute Myeloid Leukemia Cell Line HL-60R

2021

Euphorbia species have a large spectrum of traditional medicinal uses. We tested the biological activities of the essential oil (EO) of Euphorbia intisy Drake in an acquired multidrug resistance leukemia model to assess whether the EO obtained by hydrodistillation of stems was able to reverse the resistant phenotype. HL-60R cell lines are characterized by the overexpression of P-glycoprotein (P-gp), inhibitors of apoptosis proteins (IAPs) and constitutive expression of NF-κB. EO chemical composition was determined by GC/MS analysis

Synthesis of alkyl-5,8-dimethyl-6-phenyl-5,6-dihydropyrazolo[3,4-f] [1,2,3,5]tetrazepin-4(3H)-ones of pharmaceutical interest

2006

The multistep synthesis of two pyrazolo[3,4-f][1,2,3,5]tetrazepin-4(3H)-one derivatives, a new class of fused 1,2,3,5-tetrazepinones with potential antiproliferative activity, has been carried out. Owing to the instability of the above compounds, the last step of the synthesis was performed at -5/0 degrees C. The obtained tetrazepinones, when allowed to stand at r.t. for 24 h, afforded quantitatively 1-phenyl-3,6-dimethylpyrazolo [3,4-d][1,2,3] triazole.

Inhibition of Saccharomyces cerevisiae Pdr5p by a natural compound extracted from Brazilian Red Propolis

2011

Multidrug resistance of cancer cells and pathogenic microorganisms leading to the treatment failure of some forms of cancer or life-threatening bacterial or fungal infections is often caused by the overexpression of multidrug efflux pumps belonging to the ATP-binding cassette transporters superfamily. The multidrug resistance of fungal cells often involves the overexpression of efflux pumps belonging to the pleiotropic drug resistance (PDR) family of ABC transporters. Possibly the best-studied fungal PDR transporter is the multidrug resistance transporter Pdr5p of Saccharomyces cerevisiae. Some research groups have been searching for new inhibitors of these efflux pumps in order to alleviat…

Cinnamaldehyde Induces Expression of Efflux Pumps and Multidrug Resistance in Pseudomonas aeruginosa

2019

Essential oils or their components are increasingly used to fight bacterial infections. Cinnamaldehyde (CNA), the main constituent of cinnamon bark oil, has demonstrated interesting properties in vitro against various pathogens, including Pseudomonas aeruginosa. In the present study, we investigated the mechanisms and possible therapeutic consequences of P. aeruginosa adaptation to CNA. Exposure of P. aeruginosa PA14 to subinhibitory concentrations of CNA caused a strong albeit transient increase in the expression of operons that encode the efflux systems MexAB-OprM, MexCD-OprJ, MexEF-OprN, and MexXY/OprM. This multipump activation enhanced from 2- to 8-fold the resistance (MIC) of PA14 to …

Cephalosporin resistantEscherichia colifrom cancer patients in Cairo, Egypt

2013

Cephalosporin-resistant Escherichia coli has been increasingly reported worldwide. In this study, 32 cephalosporin resistant E. coli isolates identified from cancer patients in Cairo, Egypt in 2009–2010 were analyzed. Twenty-three were of phylogenetic group D, seven A and one each B1 and B2. By rep-PCR 15 phylogroup D isolates were grouped in four clusters, one with sequence type (ST) 405 and three ST68. Seventeen isolates showed single patterns. blaCTX-M-15 and aac(6')-Ib-cr were the most common resistance determinants. blaOXA-48 and blaVIM were also detected. Multidrug resistant E. coli seriously affects healthcare, especially in immunocompromised hosts, such as cancer patients.

Botanicals and phytochemicals from the bark of Hypericum roeperianum (Hypericaceae) had strong antibacterial activity and showed synergistic effects …

2021

Abstract Ethnopharmacological relevance Infections due to multidrug-resistant (MDR) bacteria constitute a real problem in the public health worldwide. Hypericum roeperianum Schimp. ex A. Rich (Hypericaceae) is used traditionally for treatment of various ailments such as abdominal pains, constipation, diarrhea, indigestion, nausea, and bacterial diseases. Aim of the study This study was aimed at investigating the antibacterial and antibiotic-modifying activity of the crude methanol extracts (HRB), ethyl-acetate soluble fraction (HRBa), residual material (HRBb), and 11 compounds from the bark of Hypericum roeperianum against multi-drug resistant (MDR) bacteria expressing active efflux pumps. …

2015

Globally, there is substantial concern regarding the challenges of treating complex drug resistance patterns in multidrug resistant tuberculosis cases. Utilising data from three different settings (Estonia, Latvia, Romania) we sought to contrast drug susceptibility profiles for multidrug resistant tuberculosis cases, highlight the difficulties in designing universal regimen, and inform future regimen selection. Demographic and microbiological surveillance data for multidrug resistant tuberculosis cases from 2004-13 were analysed. High levels of additional resistance to currently recommended second line drugs were seen in all settings, with extensive variability between countries. Accurate d…