Biochemical and Rapid Molecular Analyses to Identify Glyphosate Resistance in Lolium spp.

Lolium spp. are troublesome weeds mainly found in winter cereal crops worldwide, including Europe. In recent years resistant mechanisms have been evolved to several important herbicides. In this study we investigated the mechanisms responsible for conferring glyphosate resistance in some Lolium spp. populations. A holistic approach was used, based on dose-response experiments, determination of shikimic acid concentration in plant leaf tissue, as well as molecular analyses. More specifically, in three Lolium spp. populations the existence of a mutation in the Pro-106 codon of the 5-enolpyruvylshikimate-3 phosphate synthase (EPSPS) gene was investigated as well as the relative transcript levels of four ABC-transporter genes were monitored at three time points after glyphosate application. The results demonstrated that glyphosate resistance is a multifactor phenomenon. Relative transcript levels of the ABC-transporter genes were abundant at very early time points after glyphosate treatments. Dose-response experiments and shikimate analyses were in accordance with the findings of the quantitative PCR (qPCR) analyses. We suggest that relative expression ratio of ABC-transporter genes can be a useful tool to rapidly identify Lolium spp. populations resistant to glyphosate.

The Role of ATP-binding Cassette Transporter Genes Expression for Treatment Failure in Cutaneous Leishmaniasis

Background: Leishmaniasis is one of the common diseases transmitted by sand flies in tropical and subtropical regions of the world. Currently, antimonal derivatives are the first line of treatment. Some of the members of the ATP-binding cassette (ABC) family of Leishmania are shown to be associated with resistance to antimonial. In this study, we evaluated ABCI4, ABCG2, ABCC7, and ABCC3 gene expression in Leishmania isolated from patients with non-healing cutaneous leishmaniasis. Results: Five cases were treatment failure that all of them were identified as L. major. All treatment failure clinical isolates were L. major. Gene expression analysis in treatment failure isolates showed that the ABC transported genes had a different pattern in each isolate. ABCC7 had overexpression in all isolates. Among the treatment failure isolates, only one sample had overexpression in all ABC transporter genes under study. Conclusions: Treatment failure has been reported for cutaneous leishmaniasis worldwide. Knowledge of the molecular mechanisms of treatment failure could solve this problem. ABC transporter genes are considered controversy over the mechanisms of treatment failure outcomes. In this study, we showed that ABC transporter genes could be considered one the important mechanisms.

ATP binding cassette transporters and cancer: revisiting their controversial role

The expression of ATP-binding cassette transporter (ABC transporters) has been reported in various tissues such as the lung, liver, kidney, brain and intestine. These proteins account for the efflux of different compounds and metabolites across the membrane, thus decreasing the concentration of the toxic compounds. ABC transporter genes play a vital role in the development of multidrug resistance, which is the main obstacle that hinders the success of chemotherapy. Preclinical and clinical trials have investigated the probability of overcoming drug-associated resistance and substantial toxicities. The focus has been put on several strategies to overcome multidrug resistance. These strategies include the development of modulators that can modulate ABC transporters. This knowledge can be translated for clinical oncology treatment in the future.

Analysis of ABC Transporter Gene Expression in Atherosclerosis

ABC transporters are a large family of membrane proteins that transport chemically diverse substrates across the cell membrane. Disruption of transport mechanisms mediated by ABC transporters causes the development of various diseases, including atherosclerosis. Methods: A bioinformatic analysis of a dataset from Gene Expression Omnibus (GEO) was performed. A GEO dataset containing data on gene expression levels in samples of atherosclerotic lesions and control arteries without atherosclerotic lesions from carotid, femoral, and infrapopliteal arteries was used for analysis. To evaluate differentially expressed genes, a bioinformatic analysis was performed in comparison groups using the limma package in R (v. 4.0.2) and the GEO2R and Phantasus tools (v. 1.11.0). Results: The obtained data indicate the differential expression of many ABC transporters belonging to different subfamilies. The differential expressions of ABC transporter genes involved in lipid transport, mechanisms of multidrug resistance, and mechanisms of ion exchange are shown. Differences in the expression of transporters in tissue samples from different arteries are established. Conclusions: The expression of ABC transporter genes demonstrates differences in atherosclerotic samples and normal arteries, which may indicate the involvement of transporters in the pathogenesis of atherosclerosis.

Nrf2 signaling promotes cancer stemness, migration, and expression of ABC transporter genes in sorafenib-resistant hepatocellular carcinoma cells

Background and aim As a multiple tyrosine kinase inhibitor, sorafenib is widely used to treat hepatocellular carcinoma (HCC), but patients frequently face resistance problems. Because the mechanism controlling sorafenib-resistance is not well understood, this study focused on the connection between tumor characteristics and the Nrf2 signaling pathway in a sorafenib-resistant HCC cell line. Methods A sorafenib-resistant HCC cell line (Huh7) was developed by increasing the dose of sorafenib in the culture medium until the target concentration was reached. Cell morphology, migration/invasion rates, and expression of stemness-related and ATP-binding cassette (ABC) transporter genes were compared between sorafenib-resistant Huh7 cells and parental Huh7 cells. Next, a small interfering RNA was used to knock down Nrf2 expression in sorafenib-resistant Huh7 cells, after which cell viability, stemness, migration, and ABC transporter gene expression were examined again. Results Proliferation, migration, and invasion rates of sorafenib-resistant Huh7 cells were significantly increased relative to the parental cells with or without sorafenib added to the medium. The expression levels of stemness markers and ABC transporter genes were up-regulated in sorafenib-resistant cells. After Nrf2 was knocked down in sorafenib-resistant cells, cell migration and invasion rates were reduced, and expression levels of stemness markers and ABC transporter genes were reduced. Conclusion Nrf2 signaling promotes cancer stemness, migration, and expression of ABC transporter genes in sorafenib-resistant HCC cells.

Towards improved resistance of Corynebacterium glutamicum against nisin

The bacteriocin nisin is one of the best studied antimicrobial peptides. It is widely used as a food preservative due to its antimicrobial activity against various Gram-positive bacteria including human pathogens such as Listeria monocytogenes and others. The receptor of nisin is the universal cell wall precursor lipid II, which is present in all bacteria. Thus, nisin has a broad spectrum of target organisms. Consequently, heterologous production of nisin with biotechnological relevant organisms including Corynebacterium glutamicum is difficult. Nevertheless, bacteria have evolved several mechanisms of resistance against nisin and other cationic antimicrobial peptides (CAMPs). Here, we transferred resistance mechanisms described in other organisms to C. glutamicum with the aim to improve nisin resistance. The presented approaches included: expression of (i) nisin immunity genes nisI and/or nisFEG or (ii) nisin ABC-transporter genes of Staphylococcus aureus and its homologues of C. glutamicum, (iii) genes coding for enzymes for alanylation or lysinylation of the cell envelope to introduce positive charges, and/or (iv) deletion of genes for porins of the outer membrane. None of the attempts alone increased resistance of C. glutamicum more than two-fold. To increase resistance of C. glutamicum to levels that will allow heterologous production of active nisin at relevant titers, further studies are needed.

Repeated Ivermectin Treatment Induces Ivermectin Resistance in Strongyloides ratti by Upregulating the Expression of ATP-Binding Cassette Transporter Genes

Ivermectin (IVM) is a widely used anthelmintic. However, with widespread use comes the risk of the emergence of IVM resistance, particularly in strongyloidiasis. Adenosine triphosphate (ATP)-binding cassette (ABC) transporter genes play an important role in the IVM-resistance mechanism. Here, we aimed to establish an animal experimental model of IVM resistance by frequent treatment of Strongyloides ratti with subtherapeutic doses of IVM, resistance being evaluated by the expression levels of ABC transporter genes. Rats infected with S. ratti were placed in experimental groups as follows: 1) untreated control (control); 2) treated with the mutagen ethyl methanesulfonate (EMS); 3) injected with 100 µg/kg body weight of IVM (IVM); 4) treated with a combination of EMS and IVM (IVM+EMS). Parasites were evaluated after four generations. Extent of IVM resistance was assessed using IVM sensitivity, larval development, and expression of ABC genes. By the F4 generation, S. ratti in the IVM group exhibited significantly higher levels of IVM resistance than did other groups according to in vitro drug-sensitivity tests and inhibition of larval development (IC50 = 36.60 ng/mL; 95% CI: 31.6, 42.01). Expression levels of ABC isoform genes (ABCA, ABCF, and ABCG) were statistically significantly higher in the IVM-resistant line compared with the susceptible line. In conclusion, IVM subtherapeutic doses induced IVM resistance in S. ratti by the F4 generation with corresponding upregulation of some ABC isoform genes. The study provides a model for inducing and assessing drug resistance in Strongyloides.

Acquired ABC-transporter overexpression in cancer cells: transcriptional induction or Darwinian selection?

Acquired multidrug resistance (MDR) in tumor diseases has repeatedly been associated with overexpression of ATP-binding cassette transporters (ABC-transporters) such as P-glycoprotein. Both in vitro and in vivo data suggest that these efflux transporters can cause MDR, albeit its actual relevance for clinical chemotherapy unresponsiveness remains uncertain. The overexpression can experimentally be achieved by exposure of tumor cells to cytotoxic drugs. For simplification, the drug-mediated transporter overexpression can be attributed to two opposite mechanisms: First, increased transcription of ABC-transporter genes mediated by nuclear receptors sensing the respective compound. Second, Darwinian selection of sub-clones intrinsically overexpressing drug transporters being capable of extruding the respective drug. To date, there is no definite data indicating which mechanism truly applies or whether there are circumstances promoting either mode of action. This review summarizes experimental evidence for both theories, suggests an algorithm discriminating between these two modes, and finally points out future experimental approaches of research to answer this basic question in cancer pharmacology.