Multidrug resistance protein 1 (MRP1, ABCC1), a "multitasking" ATP-binding cassette (ABC) transporter

LncRNA HOTAIR regulates the expression of MRP1 gene through the mir-6807-5p/Egr1 axis to affect the multidrug resistance of lung cancer cells

Multi-drug resistance-associated protein 1 (MRP1) plays critical roles in the multi-drug resistance (MDR) of cancer cells, LncRNA HOTAIR is closely related to MDR in lung cancer, however, the effects of HOTAIR on MRP1 expression and MDR in lung cancer cells (A549/DDP) remain unknown. In this study, the effects of HOTAIR on MRP1 gene expression and MDR in A549/DDP cells were monitored. LncRNA HOTAIR was upregulated in A549/DDP cells, and overexpression of HOTAIR promoted MRP1 expression and MDR development. The opposite trend was observed when HOTAIR was silenced in A549/DDP cells. To uncover the role of LncRNA HOTAIR in the MDR of human lung cancer, the effects of Egr1 on MRP1 gene expression and MDR in A549/DDP cells were monitored. The results showed that Egr1 could bind to the MRP1 promoter at site -53/-42 bp and regulate MRP1 expression. Egr1 knock-down reduced MRP1 expression, while Egr1 overexpression increased it. Further, the results demonstrated that LncRNA HOTAIR mediated the effects of Egr1 on MRP1 and MDR via sponging of miR-6807-3p. Moreover, miR-6807-3p exerts its function by targeting the Egr1 3'UTR. In conclusion, the results revealed the novel HOTAIR/miR-6807-3p/Egr1 axis in the regulation of MRP1 expression and MDR in lung cancer cells.

ATP-binding cassette transporters and drug resistance in cutaneous leishmaniasis

Leishmania spp. are intracellular protozoan parasites causative of visceral and cutaneous leishmaniasis. Recognized as a neglected tropical disease affecting millions of people around the world, this affliction represents a major public health problem. In Brazil, pentavalent antimony (SbV), the main therapy used to treat all clinical forms of leishmaniasis, has become increasingly associated with treatment failure. Many factors can influence leishmaniasis treatment outcome, including low expression aquaglyceroporin by the parasite and high activity of the ATP-binding cassette (ABC) transporters, efflux pumps whose activity has been associated with drug resistance in a variety of diseases. Current evidence suggests that some ABC transporters (e.g., MRP1 and MDR1) play a role in drug resistance in leishmaniasis. One way to potentially overcome SbV resistance may be a combined therapeutic strategy involving anti-Leishmania drugs administered together with ABC transporter inhibitors; however, toxicity poses a major challenge to the adoption of this approach.

Unravelling the role of tumor microenvironment responsive nanobiomaterials in spatiotemporal controlled drug delivery for lung cancer therapy

Design and development of efficient drug delivery technologies that impart site-specificity is the need of the hour for the effective treatment of lung cancer. The emergence of materials science and nanotechnology partially helped drug delivery scientists to achieve this objective. Various stimuli-responsive materials that undergo degradation at the pathological tumor microenvironment (TME) have been developed and explored for drug delivery applications using nanotechnological approaches. Nanoparticles (NPs), owing to their small size and high surface area to volume ratio, demonstrated enhanced cellular internalization, permeation, and retention at the tumor site. Such passive accumulation of stimuli-responsive materials helped to achieve spatiotemporally controlled and targeted drug delivery within the tumors. In this review, we discussed various stimuli-physical (interstitial pressure, temperature, and stiffness), chemical (pH, hypoxia, oxidative stress, and redox state), and biological (receptor expression, efflux transporters, immune cells, and their receptors or ligands)-that are characteristic to the TME. We mentioned an array of biomaterials-based nanoparticulate delivery systems that respond to these stimuli and control drug release at the TME. Further, we discussed nanoparticle-based combinatorial drug delivery strategies. Finally, we presented our perspectives on challenges related to scale-up, clinical translation, and regulatory approvals.

Protective role of ABCC drug subfamily resistance transporters (ABCC1-7) in intestinal inflammation

The ABCC subfamily contains thirteen members. Nine of these transporters are called multidrug resistance proteins (MRPs). The MRPs have been associated with developing ulcerative colitis (UC). This study aimed to evaluate the ABCC expression in UC patients and its role in a dextran sulfate sodium (DSS)-induced colitis mice model under 5-aminosalicylates or methylprednisolone treatment and compared with control without inflammation. DSS-induced colitis mice were treated with 5-aminosalicylates (50 mg/kg 24 h) or methylprednisolone (2 mg/kg 24 h). Human rectal biopsies were obtained from UC patients. The abcc-relative mRNA levels and protein expression were determined by RT-PCR and immunohistochemistry. abcc4, abcc5, and abcc6 mRNA levels were significantly increased in DSS-induced colitis compared to the other groups. The 5-aminosalicylate treatment dramatically increased the abcc2 and abcc3 mRNA levels vs. control. Methylprednisolone treatment increased abcc1 vs. DSS-induced colitis and colitis treated with 5-aminosalicylate. Immunohistochemical analysis revealed down-regulation of ABCC1/ABCC2/ABCC5/ABCC7 in mice colitis vs. control. Treatment with 5-aminosalicylate restored ABCC5 levels, while methylprednisolone restored ABCC2/ABCC5/ABCC7 in colitis mice at similar control levels. Relative mRNA levels of mrp1-5 were increased in active UC patients vs. control. ABCC2/ABCC4/ABCC7 were conspicuously expressed in the mucosa of 5-aminosalicylate and/or methylprednisolone-treated UC patients, while ABCC2/ABCC4/ABCC5/ABCC7 in submucosa, ABCC1/ABCC5/ABCC7 in muscular, and ABCC1/ABCC4/ABCC5/ABCC7 in serosa were expressed vs. controls. This is the first report about the differential up-regulation of the ABCC subfamily gene and protein expression in DSS-induced colitis under aminosalicylates or methylprednisolone treatment.

Multidrug Resistance Reversed by Maleimide Interactions. A Biological and Synthetic Overview for an Emerging Field

Multidrug Resistance (MDR) can be considered one of the most frightening adaptation types in bacteria, fungi, protozoa, and eukaryotic cells. It allows the organisms to survive the attack of many drugs used in the daily basis. This forces the development of new and more complex, highly specific drugs to fight diseases. Given the high usage of medicaments, poor variation in active chemical cores, and self-medication, the appearance of MDR is more frequent each time, and has been established as a serious medical and social problem. Over the years it has been possible the identification of several genes and proteins responsible for MDR and with that the development of blockers of them to reach MDR reversion and try to avoid a global problem. These mechanisms also have been observed in cancer cells, and several calcium channel blockers have been successful in MDR reversion, and the maleimide can be found included in them. In this review, we explore particularly the tree main proteins involved in cancer chemoresistance, MRP1 (encoded by ABCC1), BCRP (encoded by ABCG2) and P-gp (encoded by ABCB1). The participation of P-gp is remarkably important, and several aspects of its regulations are discussed. Additionally, we address the history, mechanisms, reversion efforts, and we specifically focused on the maleimide synthesis as MDR-reversers in co-administration, as well as on how their biological applications are imperative to expand the available information and explore a very plausible MDR reversion source.

Cryo-EM structures of ABCC1 revealing new conformational dynamics in the resting state

ABCC1/MRP1 in the C branch of Adenosine triphosphate binding cassette (ABC) transporters superfamily, is directly linked to multiple drug resistance in chemotherapy. Here, to further understand the conformational dynamics of ABCC1, we performed single-particle cryo-electron microscopy analysis of purified bovine ABCC1. Two conformational states were found coexisted with nearly equal population. While one state has a wider substrate transporting pathway, akin to the previously reported apo structure, the other is narrower, despite the empty substrate pocket. In addition, multiple lipid-binding interfaces were identified based on the presence of rod-shaped, unmodeled, non-protein densities in the resolved density maps, potentially contributing to the stabilization of TMD0 domain and activity regulation of ABCC1. Further, we found that three asparagine residues in bovine ABCC1 are glycosylated. Together, our study provides fresh insights into the structural features and conformational dynamics of bovine ABCC1, offering a new framework for understanding the function and regulatory mechanisms of ABCC1.

Aryl Hydrocarbon Receptor Alleviates Hepatic Fibrosis by Inducing Hepatic Stellate Cell Ferroptosis

Liver injury-induced activation of hepatic stellate cells (HSCs) is a crucial step in the progression of liver fibrosis. The aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, is highly expressed in the liver. However, the role of AHR in liver fibrosis remains controversial. Our study revealed that the nontoxic ligand YH439 directly activated the AHR and regulated the expression of multidrug-resistant protein 1 (Mrp1) in mouse hepatic stellate cells (mHSCs), thereby diminishing the antioxidant capacity of mHSCs by promoting GSH efflux, and specifically inducing mHSCs ferroptosis without affecting hepatocytes. In a chronic liver fibrosis model, YH439 activated AHR to promote mHSC ferroptosis without causing hepatocyte ferroptosis, thereby alleviating liver fibrosis. Conclusively, this study shows that AHR alleviates liver fibrosis in mice by selectively inducing mHSC ferroptosis without causing hepatocyte ferroptosis and suggests that AHR is a potential target for the treatment of liver fibrosis.

Structure of a dimeric full-length ABC transporter

Activities of ATP binding cassette (ABC) proteins are regulated by multiple mechanisms, including protein interactions, phosphorylation, proteolytic processing, and/or oligomerization of the ABC protein itself. Here we present the structure of yeast cadmium factor 1 (Ycf1p) in its mature form following cleavage by Pep4p protease. Ycf1p, a C subfamily ABC protein (ABCC), is homologue of human multidrug resistance protein 1. Remarkably, a portion of cleaved Ycf1p forms a well-ordered dimer, alongside monomeric particles also present in solution. While numerous other ABC proteins have been proposed to dimerize, no high-resolution structures have been reported. Both phosphorylation of the regulatory (R) region and ATPase activity are lower in the Ycf1p dimer compared to the monomer, indicating that dimerization affects Ycf1p function. The interface between Ycf1p protomers features protein-protein interactions and contains bound lipids, suggesting that lipids stabilize the dimer. The Ycf1p dimer structure may inform the dimerization interfaces of other ABCC dimers.

lncRNAs: New players of cancer drug resistance via targeting ABC transporters

Cancer drug resistance poses a significant obstacle to successful chemotherapy, primarily driven by the activity of ATP-binding cassette (ABC) transporters, which actively efflux chemotherapeutic agents from cancer cells, reducing their intracellular concentrations and therapeutic efficacy. Recent studies have highlighted the pivotal role of long noncoding RNAs (lncRNAs) in regulating this resistance, positioning them as crucial modulators of ABC transporter function. lncRNAs, once considered transcriptional noise, are now recognized for their complex regulatory capabilities at various cellular levels, including chromatin modification, transcription, and post-transcriptional processing. This review synthesizes current research demonstrating how lncRNAs influence cancer drug resistance by modulating the expression and activity of ABC transporters. lncRNAs can act as molecular sponges, sequestering microRNAs that would otherwise downregulate ABC transporter genes. Additionally, they can alter the epigenetic landscape of these genes, affecting their transcriptional activity. Mechanistic insights reveal that lncRNAs contribute to the activity of ABC transporters, thereby altering the efflux of chemotherapeutic drugs and promoting drug resistance. Understanding these interactions provides a new perspective on the molecular basis of chemoresistance, emphasizing the regulatory network of lncRNAs and ABC transporters. This knowledge not only deepens our understanding of the biological mechanisms underlying drug resistance but also suggests novel therapeutic strategies. In conclusion, the intricate interplay between lncRNAs and ABC transporters is crucial for developing innovative solutions to combat cancer drug resistance, underscoring the importance of continued research in this field.

First-in-human evaluation of 6-bromo-7-[11C]methylpurine, a PET tracer for assessing the function of multidrug resistance-associated proteins in different tissues

PURPOSE

Multidrug resistance-associated protein 1 (MRP1) is a transport protein with a widespread tissue distribution, which has been implicated in the pathophysiology of Alzheimer's and chronic respiratory disease. PET with 6-bromo-7-[11C]methylpurine ([11C]BMP) has been used to measure MRP1 function in rodents. In this study, [11C]BMP was for the first time characterised in humans to assess the function of MRP1 and other MRP subtypes in different tissues.

METHODS

Thirteen healthy volunteers (7 men, 6 women) underwent dynamic whole-body PET scans on a long axial field-of-view (LAFOV) PET/CT system after intravenous injection of [11C]BMP. Three subjects of each sex were scanned a second time to assess reproducibility. Volumes of interest were outlined for MRP-expressing tissues (cerebral cortex, cerebellum, choroid plexus, retina, lungs, myocardium, kidneys, and liver). From the time-activity curves, the elimination rate constant (kE, h- 1) was derived as a parameter for tissue MRP function and its test-retest variability (TRTV, %) was calculated. Radiation dosimetry was calculated using the Medical Internal Radiation Dose (MIRD) methodology.

RESULTS

Mean kE and corresponding TRTV values were: cerebral cortex: 0.055 ± 0.010 h- 1 (- 4 ± 24%), cerebellum: 0.033 ± 0.009 h- 1 (1 ± 39%), choroid plexus: 0.292 ± 0.059 h- 1 (0.1 ± 16%), retina: 0.234 ± 0.045 h- 1 (30 ± 38%), lungs: 0.875 ± 0.095 h- 1 (- 3 ± 11%), myocardium: 0.641 ± 0.105 h- 1 (11 ± 25%), kidneys: 1.378 ± 0.266 h- 1 (14 ± 16%), and liver: 0.685 ± 0.072 h- 1 (7 ± 9%). Significant sex differences were found for kE in the cerebellum, lungs and kidneys. Effective dose was 4.67 ± 0.18 µSv/MBq for men and 4.55 ± 0.18 µSv/MBq for women.

CONCLUSION

LAFOV PET/CT with [11C]BMP potentially allows for simultaneous assessment of MRP function in multiple human tissues. Mean TRTV of kE in different tissues was in an acceptable range, except for the retina. The radiation dosimetry of [11C]BMP was in the typical range of 11C-tracers. LAFOV PET/CT holds great potential to assess at a whole-body, multi-tissue level molecular targets relevant for drug disposition in humans.

TRIAL REGISTRATION

EudraCT 2021-006348-29. Registered 15 December 2021.

Exploring the genome-wide transcriptomic responses of Bulinus truncatus to Schistosoma haematobium infection: An important host-parasite system involved in the transmission of human urogenital schistosomiasis

Freshwater snails of the genus Bulinus are critical hosts for Schistosoma haematobium, the causative agent of urogenital schistosomiasis. Among the 37 recognized Bulinus species, B. truncatus is a key vector. Using RNA sequencing (RNAseq), we investigated the genome-wide transcriptional responses of B. truncatus to S. haematobium infection. Our findings suggest that snails employ a complex defense strategy against the parasites by up-regulating genes involved in immune response, stress reaction, structural integrity, metabolism, and detoxification. In response, schistosome parasites appear to manipulate the snail's defense system, as evidenced by the suppression of immune-related genes such as ficolin, peptidoglycan recognition protein, and C-type lectin domain-containing protein genes. The down-regulation of biomphalysin 9, compared to its function in Biomphalaria glabrata, indicates divergent immune strategies among snail hosts. Additionally, we compared transcriptome profiles between embryos and juveniles, providing insights into developmental processes. This study offers valuable genomic data for Bulinus snails, illuminating the molecular interactions between bulinids and schistosomes, and advancing our understanding of their developmental biology.

An in-depth examination of Per- and Polyfluoroalkyl (PFAS) effects on transporters, with emphasis on the ABC superfamily: A critical review

Per- and polyfluoroalkyl (PFAS) substances are a type of chemical compound unique for their multiple carbon-fluorine bonds, imbuing them with strength and environmental permanence. While legacy substances have been phased out due to human health risks, short-chain and alternative PFAS remain omnipresent. However, a detailed explanation for the pathways through which PFAS interact on a cellular and molecular level is still largely unknown, and the human health effects remain mechanistically unexplained. Of particular interest when focusing on this topic are the interactions between these exogenous chemicals and plasma and membrane proteins. Such proteins include serum albumin which can transport PFAS throughout the body, solute carrier proteins (SLC) and ATP binding cassette (ABC) transporters which are able to move PFAS into and out of cells, and proteins and nuclear receptors which interact with PFAS intracellularly. ABC transporters as a family have little available human data despite being responsible for the export of endogenous substances and drugs throughout the body. The multifactorial regulation of these crucial transporters is affected directly and indirectly by PFAS. Changes, which can include alterations to membrane transport activity and differences in protein expression, vary greatly depending on the specific PFAS and protein of interest. Together, the myriad of changes caused by understudied PFAS exposure to a class of understudied proteins crucial to cellular function and drug treatments has not been fully explored regarding human health and presents room for further exploration. This critical work aims to provide a novel framework of existing human data on PFAS and ABC transporters, allowing for future advancement and investigation into human transporter activity, mechanisms of regulation, and interactions with emerging contaminants.

Brain-to-blood transport of fluorescein in vitro

Investigating blood-brain barrier (BBB) dysfunction has become a pre-clinical and clinical research focus as it accompanies many neurological disorders. Nevertheless, knowledge of how diagnostic BBB tracers cross the endothelium from blood-to-brain or vice versa often remains incomplete. In particular, brain-to-blood transport (efflux) may reduce tracer extravasation of intravascularly (i.v.) applied tracers. Conversely, impaired efflux could mimic phenotypic extravasation. Both processes would affect conclusions on BBB properties primarily attributed to blood-to-brain leakage. Here, we specifically investigated efflux of fluorescent BBB tracers, focusing on the most common non-toxic marker, sodium fluorescein, which is applicable in patients. We used acute neocortical slices from mice and applied fluorescein, sulforhodamine-B, rhodamine-123, FITC dextran to the artificial cerebrospinal fluid. Anionic low molecular weight (MW) fluorescein and sulforhodamine-B, but not ~ 10-fold larger FITC-dextran and cationic low MW rhodamine-123, showed efflux into the lumen of blood vessels. Our data suggest that fluorescein efflux depends on organic anion transporter polypeptides (Oatp) rather than P-glycoprotein. Furthermore, sodium-potassium ATPase inhibition and incomplete oxygen-glucose deprivation (OGD, 20% O2) reduced fluorescein efflux, while complete OGD (0% O2) abolished efflux. We provide evidence for active efflux of fluorescein in vitro. Impaired efflux of fluorescein could thus contribute to the frequently observed BBB dysfunction in neuropathologies in addition to blood-to-brain leakage.

Characterization of mitochondrial metabolism related molecular subtypes and immune infiltration in colorectal adenocarcinoma

Colorectal adenocarcinoma (COAD) is the most common subtype of colorectal cancer. Due to the imperfect prognosis of COAD, related prognostic factors and possible mechanisms need to be further investigated. During tumor development, mitochondria help tumor cells survive in a variety of ways, so that further screening of mitochondrial metabolism related targets has positive implications for COAD. We screened the mitochondrial metabolism-related genes (MMRG) associated with the COAD prognosis and explored the MMRG-related molecular subtype characteristics of by unsupervised consensus clustering analysis. Using ESTIMATE and ssGSEA algorithms, we evaluated the immunoinfiltration characteristic landscape of different molecular subtypes defined by MMRG. Combining the expression profiles of differentially expressed genes associated with the MMRG subgroup and the survival characteristics of COAD, we constructed an MMRG prognostic model using LASSO-univariate Cox analysis and successfully validated its impact on independently predicting risk stratification of COAD. The potential clinical value of the MMRG score was subsequently evaluated by subgroup immunoinfiltration characteristics and drug susceptibility prediction analysis. We also offer SEC11A as a new potential target for COAD by single-cell sequencing analysis. The effect of SEC11A on the proliferation, invasion abilities and mitochondrial dysfunction of COAD cells was confirmed through in vitro experiments. Our study provides new insights into the role of MMRG and new target for COAD potential intervention.

Role of mitochondria in reno-cardiac diseases: A study of bioenergetics, biogenesis, and GSH signaling in disease transition

Acute kidney injury (AKI) and chronic kidney disease (CKD) are global health burdens with rising prevalence. Their bidirectional relationship with cardiovascular dysfunction, manifesting as cardio-renal syndromes (CRS) types 3 and 4, underscores the interconnectedness and interdependence of these vital organ systems. Both the kidney and the heart are critically reliant on mitochondrial function. This organelle is currently recognized as a hub in signaling pathways, with emphasis on the redox regulation mediated by glutathione (GSH). Mitochondrial dysfunction, including impaired bioenergetics, redox, and biogenesis pathways, are central to the progression of AKI to CKD and the development of CRS type 3 and 4. This review delves into the metabolic reprogramming and mitochondrial redox signaling and biogenesis alterations in AKI, CKD, and CRS. We examine the pathophysiological mechanisms involving GSH redox signaling and the AMP-activated protein kinase (AMPK)-sirtuin (SIRT)1/3-peroxisome proliferator-activated receptor-gamma coactivator (PGC-1α) axis in these conditions. Additionally, we explore the therapeutic potential of GSH synthesis inducers in mitigating these mitochondrial dysfunctions, as well as their effects on inflammation and the progression of CKD and CRS types 3 and 4.

Potential suppression of multidrug-resistance-associated protein 1 by coumarin derivatives: an insight from molecular docking and MD simulation studies

Human MRP1 protein plays a vital role in cancer multidrug resistance. Coumarins show promising pharmacological properties. Virtual screening, ADMET, molecular docking and molecular dynamics (MD) simulations were utilized as pharmacoinformatic tools to identify potential MRP1 inhibitors among coumarin derivatives. Using in silico ADMET, 50 hits were further investigated for their selectivity toward the nucleotide-binding domains (NBDs) of MRP1 using molecular docking. Accordingly, coumarin, its symmetrical ketone derivative Lig. No. 4, and Reversan were candidates for focused docking study with the NBDs domains compared with ATP. The result indicates that Lig. No. 4, with the best binding score, interacts with NBDs via hydrogen bonds with residues: GLN713, LYS684, GLY683, CYS682 in NBD1, and GLY1432, GLY771, SER769 and GLN1374 in NBD2, which mostly overlap with ATP binding residues. Moreover, doxorubicin (Doxo) was docked to the transmembrane domains (TMDs) active site of MRP1. Doxo interaction with TMDs was subjected to MD simulation in the NBDs free and occupied with Lig. No. 4 states. The results showed that Doxo interacts more strongly with TMD residues in inward facing feature of TMDs helices. However, when Lig. No. 4 exists in NBDs, Doxo interactions are different, and TMD helices show more outward-facing conformation. This result may suggest a partial competitive inhibition mechanism for the Lig. No. 4 on MRP1 compared with ATP. So, it may inhibit active complex formation by interfering with ATP entrance to NBDs and locking MRP1 conformation in outward-facing mode. This study suggests a valuable coumarin derivative that can be further investigated for potent MRP1 inhibitors.Communicated by Ramaswamy H. Sarma.

Exploring potential molecular targets and therapeutic efficacy of beauvericin in triple-negative breast cancer cells

Triple negative breast cancer (TNBC) presents a significant global health concern due to its aggressive nature, high mortality rate and limited treatment options, highlighting the urgent need for targeted therapies. Beauvericin, a bioactive fungal secondary metabolite, possess significant anticancer potential, although its molecular targets in cancer cells remain unexplored. This study has investigated possible molecular targets of beauvericin and its therapeutic insights in TNBC cells. In silico studies using molecular docking and MD simulation predicted the molecular targets of beauvericin. The identified targets included MRP-1 (ABCC1), HDAC-1, HDAC-2, LCK and SYK with average binding energy of -90.1, -44.3, -72.1, -105 and -60.8 KJ/mol, respectively, implying its multifaceted roles in reversing drug resistance, inhibiting epigenetic modulators and oncogenic tyrosine kinases. Beauvericin has significantly reduced the viability of MDA-MB-231 and MDA-MB-468 cells, with IC50 concentrations of 4.4 and 3.9 µM, while concurrently elevating the intracellular ROS by 9.0 and 7.9 folds, respectively. Subsequent reduction of mitochondrial transmembrane potential in TNBC cells, has confirmed the induction of oxidative stress, leading to apoptotic cell death, as observed by flow cytometric analyses. Beauvericin has also arrested cell cycle at G1-phase and impaired the spheroid formation and clonal expansion abilities of TNBC cells. The viability of spheroids was reduced upon beauvericin treatment, exhibiting IC50 concentrations of 10.3 and 6.2 µM in MDA-MB-468 and MDA-MB-231 cells, respectively. In conclusion, beauvericin has demonstrated promising therapeutic potential against TNBC cells through possible inhibition of MRP-1 (ABCC1), HDAC-1, HDAC-2, LCK and SYK.

Sonic Hedgehog activates prostaglandin signaling to stabilize primary cilium length

Sonic Hedgehog (SHH) is a driver of embryonic patterning that, when corrupted, triggers developmental disorders and cancers. SHH effector responses are organized through primary cilia (PC) that grow and retract with the cell cycle and in response to extracellular cues. Disruption of PC homeostasis corrupts SHH regulation, placing significant pressure on the pathway to maintain ciliary fitness. Mechanisms by which ciliary robustness is ensured in SHH-stimulated cells are not yet known. Herein, we reveal a crosstalk circuit induced by SHH activation of Phospholipase A2α that drives ciliary E-type prostanoid receptor 4 (EP4) signaling to ensure PC function and stabilize ciliary length. We demonstrate that blockade of SHH-EP4 crosstalk destabilizes PC cyclic AMP (cAMP) equilibrium, slows ciliary transport, reduces ciliary length, and attenuates SHH pathway induction. Accordingly, Ep4-/- mice display shortened neuroepithelial PC and altered SHH-dependent neuronal cell fate specification. Thus, SHH initiates coordination between distinct ciliary receptors to maintain PC function and length homeostasis for robust downstream signaling.

Characterization of a deazaflavin analog as a potent inhibitor of multidrug resistance-associated protein 1

Selective inhibition of overexpressed ATP binding cassette (ABC) transporters is an attractive approach to enhancing the efficacy of chemotherapeutics in multidrug resistant cancers. Previously, we reported that the cancer sensitizing effect of deazaflavin analogs, an important chemotype for developing combination treatments with topoisomerase II (TOP2) poisons, is associated with increased intracellular drug accumulation. Here we report the characterization of ZW-1226, a deazaflavin analog, as a potent inhibitor of multidrug resistance-associated protein 1 (MRP1). Specifically, ZW-1226 inhibited MRP1 with a 16-fold higher potency than the most widely used positive control MK-571 in vesicular transport assay and displayed excellent selectivity indices exceeding 100 over other major ABC transporters, including P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), MRP2 and MRP3. Mechanistically, we revealed that its MRP1 inhibitory action requires the participation of GSH. In chemo-sensitization test, ZW-1226 fully reversed the MRP1-mediated drug resistance to TOP2 poisons etoposide (ETP) and doxorubicin (DOX) in H69AR cells and conferred CC50s comparable to those in the sensitive parental NCI-H69 cells. The sensitization was associated with boosted intracellular accumulation of ETP and DOX and elevated endogenous GSH. Moreover, ZW-1226 showed potential to occupy the leukotriene C4 binding site in molecular docking with bovine MRP1, presumably with the help of GSH. Lastly, ZW-1226 exhibited high tissue to plasma partitions in mice but did not alter ETP distribution to normal tissues, suggesting it could be a viable lead with desirable pharmacokinetic properties to warrant further investigation.

ABCC1 deficiency potentiated noise-induced hearing loss in mice by impairing cochlear antioxidant capacity

The ABCC1 gene belongs to the ATP-binding cassette membrane transporter superfamily, which plays a crucial role in the efflux of various endogenous and exogenous substances. Mutations in ABCC1 can result in autosomal dominant hearing loss. However, the specific roles of ABCC1 in auditory function are not fully understood. Through immunofluorescence, we found that ABCC1 was expressed in microvascular endothelial cells (ECs) of the stria vascularis (StV) in the murine cochlea. Then, an Abcc1 knockout mouse model was established by using CRISPR/Cas9 technology to elucidate the role of ABCC1 in the inner ear. The ABR threshold did not significantly differ between WT and Abcc1-/- mice at any age studied. After noise exposure, the ABR thresholds of the WT and Abcc1-/- mice were significantly elevated. Interestingly, after 14 days of noise exposure, ABR thresholds largely returned to pre-exposure levels in WT mice but not in Abcc1-/- mice. Our subsequent experiments showed that microvascular integrity in the StV was compromised and that the number of outer hair cells and the number of ribbons were significantly decreased in the cochleae of Abcc1-/- mice post-exposure. Besides, the production of ROS and the accumulation of 4-HNE significantly increased. Furthermore, StV microvascular ECs were cultured to elucidate the role of ABCC1 in these cells under glucose oxidase challenge. Notably, 30 U/L glucose oxidase (GO) induced severe oxidative stress damage in Abcc1-/- cells. Compared with WT cells, the ROS and 4-HNE levels and the apoptotic rate were significantly elevated in Abcc1-/- cells. In addition, the reduced GSH/GSSG ratio was significantly decreased in Abcc1-/- cells after GO treatment. Taken together, Abcc1-/- mice are more susceptible to noise-induced hearing loss, possibly because ABCC1 knockdown compromises the GSH antioxidant system of StV ECs. The exogenous antioxidant N-acetylcysteine (NAC) may protect against oxidative damage in Abcc1-/- murine cochleae and ECs.

Targeting estrogen metabolism in high-grade serous ovarian cancer shows promise to overcome platinum resistance

The high mortality rate due to chemoresistance in patients with high-grade ovarian cancer (HGSOC) emphasizes the urgent need to determine optimal treatment strategies for advanced and recurrent cases. Our study investigates the interplay between estrogens and chemoresistance in HGSOC and shows clear differences between platinum-sensitive and -resistant tumors. Through comprehensive transcriptome analyzes, we uncover differences in the expression of genes of estrogen biosynthesis, metabolism, transport and action underlying platinum resistance in different tissues of HGSOC subtypes and in six HGSOC cell lines. Furthermore, we identify genes involved in estrogen biosynthesis and metabolism as prognostic biomarkers for HGSOC. Additionally, our study elucidates different patterns of estrogen formation/metabolism and their effects on cell proliferation between six HGSOC cell lines with different platinum sensitivity. These results emphasize the dynamic interplay between estrogens and HGSOC chemoresistance. In particular, targeting the activity of steroid sulfatase (STS) proves to be a promising therapeutic approach with potential efficacy in limiting estrogen-driven cell proliferation. Our study reveals potential prognostic markers as well as identifies novel therapeutic targets that show promise for overcoming resistance and improving treatment outcomes in HGSOC.

Therapy-induced senescence in breast cancer: an overview

Outcomes for women with breast cancer have improved dramatically in recent decades. However, many patients present with intrinsic drug resistance and others are initially sensitive to anti-cancer drugs but acquire resistance during the course of their treatment, leading to recurrence and/or metastasis. Drug therapy-induced senescence (TIS) is a form of drug resistance characterised by the induction of cell cycle arrest and the emergence of a senescence-associated secretory phenotype (SASP) that can develop in response to chemo- and targeted- therapies. A wide range of anticancer interventions can lead to cell cycle arrest and SASP induction, by inducing genotoxic stress, hyperactivation of signalling pathways or oxidative stress. TIS can be anti-tumorigenic in the short-term, but pro-tumorigenic in the long-term by creating a pro-inflammatory and immunosuppressive microenvironment. Moreover, the SASP can promote angiogenesis and epithelial-mesenchymal transition in neighbouring cells. In this review, we will describe the characteristics of TIS in breast cancer and detail the changes in phenotype that accompany its induction. We also discuss strategies for targeting senescent cancer cells in order to prevent or delay tumour recurrence.

Vitamin B12 Metabolism: A Network of Multi-Protein Mediated Processes

The water-soluble vitamin, vitamin B12, also known as cobalamin, plays a crucial role in cellular metabolism, particularly in DNA synthesis, methylation, and mitochondrial functionality. Its deficiency can lead to hematological and neurological disorders; however, the manifestation of these clinical outcomes is relatively late. It leads to difficulties in the early diagnosis of vitamin B12 deficiency. A prolonged lack of vitamin B12 may have severe consequences including increased morbidity to neurological and cardiovascular diseases. Beyond inadequate dietary intake, vitamin B12 deficiency might be caused by insufficient bioavailability, blood transport disruptions, or impaired cellular uptake and metabolism. Despite nearly 70 years of knowledge since the isolation and characterization of this vitamin, there are still gaps in understanding its metabolic pathways. Thus, this review aims to compile current knowledge about the crucial proteins necessary to efficiently accumulate and process vitamin B12 in humans, presenting these systems as a multi-protein network. The epidemiological consequences, diagnosis, and treatment of vitamin B12 deficiency are also highlighted. We also discuss clinical warnings of vitamin B12 deficiency based on the ongoing test of specific moonlighting proteins engaged in vitamin B12 metabolic pathways.

Ferroptosis: Biology and Role in Gastrointestinal Disease

Ferroptosis is a form of nonapoptotic cell death that involves iron-dependent phospholipid peroxidation induced by accumulation of reactive oxygen species, and results in plasma membrane damage and the release of damage-associated molecular patterns. Ferroptosis has been implicated in aging and immunity, as well as disease states including intestinal and liver conditions and cancer. To date, several ferroptosis-associated genes and pathways have been implicated in liver disease. Although ferroptotic cell death is associated with dysfunction of the intestinal epithelium, the underlying molecular basis is poorly understood. As the mechanisms regulating ferroptosis become further elucidated, there is clear potential to use ferroptosis to achieve therapeutic benefit.

The impact of ATP-binding cassette transporters in the diseased brain: Context matters

ATP-binding cassette (ABC) transporters facilitate the movement of diverse molecules across cellular membranes, including those within the CNS. While most extensively studied in microvascular endothelial cells forming the blood-brain barrier (BBB), other CNS cell types also express these transporters. Importantly, disruptions in the CNS microenvironment during disease can alter transporter expression and function. Through this comprehensive review, we explore the modulation of ABC transporters in various brain pathologies and the context-dependent consequences of these changes. For instance, downregulation of ABCB1 may exacerbate amyloid beta plaque deposition in Alzheimer's disease and facilitate neurotoxic compound entry in Parkinson's disease. Upregulation may worsen neuroinflammation by aiding chemokine-mediated CD8 T cell influx into multiple sclerosis lesions. Overall, ABC transporters at the BBB hinder drug entry, presenting challenges for effective pharmacotherapy. Understanding the context-dependent changes in ABC transporter expression and function is crucial for elucidating the etiology and developing treatments for brain diseases.

Cadmium transport by mammalian ATP-binding cassette transporters

Cellular responses to toxic metals depend on metal accessibility to intracellular targets, reaching interaction sites, and the intracellular metal concentration, which is mainly determined by uptake pathways, binding/sequestration and efflux pathways. ATP-binding cassette (ABC) transporters are ubiquitous in the human body-usually in epithelia-and are responsible for the transfer of indispensable physiological substrates (e.g. lipids and heme), protection against potentially toxic substances, maintenance of fluid composition, and excretion of metabolic waste products. Derailed regulation and gene variants of ABC transporters culminate in a wide array of pathophysiological disease states, such as oncogenic multidrug resistance or cystic fibrosis. Cadmium (Cd) has no known physiological role in mammalians and poses a health risk due to its release into the environment as a result of industrial activities, and eventually passes into the food chain. Epithelial cells, especially within the liver, lungs, gastrointestinal tract and kidneys, are particularly susceptible to the multifaceted effects of Cd because of the plethora of uptake pathways available. Pertinent to their broad substrate spectra, ABC transporters represent a major cellular efflux pathway for Cd and Cd complexes. In this review, we summarize current knowledge concerning transport of Cd and its complexes (mainly Cd bound to glutathione) by the ABC transporters ABCB1 (P-glycoprotein, MDR1), ABCB6, ABCC1 (multidrug resistance related protein 1, MRP1), ABCC7 (cystic fibrosis transmembrane regulator, CFTR), and ABCG2 (breast cancer related protein, BCRP). Potential detoxification strategies underlying ABC transporter-mediated efflux of Cd and Cd complexes are discussed.

Fetus Exposure to Drugs and Chemicals: A Holistic Overview on the Assessment of Their Transport and Metabolism across the Human Placental Barrier

BACKGROUND

The placenta exerts a crucial role in fetus growth and development during gestation, protecting the fetus from maternal drugs and chemical exposure. However, diverse drugs and chemicals (xenobiotics) can penetrate the maternal placental barrier, leading to deleterious, adverse effects concerning fetus health. Moreover, placental enzymes can metabolize drugs and chemicals into more toxic compounds for the fetus. Thus, evaluating the molecular mechanisms through which drugs and chemicals transfer and undergo metabolism across the placental barrier is of vital importance. In this aspect, this comprehensive literature review aims to provide a holistic approach by critically summarizing and scrutinizing the potential molecular processes and mechanisms governing drugs and chemical transfer and metabolism across the placental barrier, which may lead to fetotoxicity effects, as well as analyzing the currently available experimental methodologies used to assess xenobiotics placental transfer and metabolism.

METHODS

A comprehensive and in-depth literature review was conducted in the most accurate scientific databases such as PubMed, Scopus, and Web of Science by using relevant and effective keywords related to xenobiotic placental transfer and metabolism, retrieving 8830 published articles until 5 February 2024. After applying several strict exclusion and inclusion criteria, a final number of 148 relevant published articles were included.

RESULTS

During pregnancy, several drugs and chemicals can be transferred from the mother to the fetus across the placental barrier by either passive diffusion or through placental transporters, resulting in fetus exposure and potential fetotoxicity effects. Some drugs and chemicals also appear to be metabolized across the placental barrier, leading to more toxic products for both the mother and the fetus. At present, there is increasing research development of diverse experimental methodologies to determine the potential molecular processes and mechanisms of drug and chemical placental transfer and metabolism. All the currently available methodologies have specific strengths and limitations, highlighting the strong demand to utilize an efficient combination of them to obtain reliable evidence concerning drug and chemical transfer and metabolism across the placental barrier. To derive the most consistent and safe evidence, in vitro studies, ex vivo perfusion methods, and in vivo animal and human studies can be applied together with the final aim to minimize potential fetotoxicity effects.

CONCLUSIONS

Research is being increasingly carried out to obtain an accurate and safe evaluation of drug and chemical transport and metabolism across the placental barrier, applying a combination of advanced techniques to avoid potential fetotoxic effects. The improvement of the currently available techniques and the development of novel experimental protocols and methodologies are of major importance to protect both the mother and the fetus from xenobiotic exposure, as well as to minimize potential fetotoxicity effects.

Glutathione Depletion and Stalwart Anticancer Activity of Metallotherapeutics Inducing Programmed Cell Death: Opening a New Window for Cancer Therapy

The cellular defense system against exogenous substances makes therapeutics inefficient as intracellular glutathione (GSH) exhibits an astounding antioxidant activity in scavenging reactive oxygen species (ROS) or reactive nitrogen species (RNS) or other free radicals produced by the therapeutics. In the cancer cell microenvironment, the intracellular GSH level becomes exceptionally high to fight against oxidative stress created by the production of ROS/RNS or any free radicals, which are the byproducts of intracellular redox reactions or cellular respiration processes. Thus, in order to maintain redox homeostasis for survival of cancer cells and their rapid proliferation, the GSH level starts to escalate. In this circumstance, the administration of anticancer therapeutics is in vain, as the elevated GSH level reduces their potential by reduction or by scavenging the ROS/RNS they produce. Therefore, in order to augment the therapeutic potential of anticancer agents against elevated GSH condition, the GSH level must be depleted by hook or by crook. Hence, this Review aims to compile precisely the role of GSH in cancer cells, the importance of its depletion for cancer therapy and examples of anticancer activity of a few selected metal complexes which are able to trigger cancer cell death by depleting the GSH level.

Differentially expressed genes associated with high metabolic tumor volume served as diagnostic markers and potential therapeutic targets for pancreatic cancer

BACKGROUND

The lack of distinct biomarkers for pancreatic cancer is a major cause of early-stage detection difficulty. The pancreatic cancer patient group with high metabolic tumor volume (MTV), one of the values measured from positron emission tomography-a confirmatory method and standard care for pancreatic cancer, showed a poorer prognosis than those with low MTV. Therefore, MTV-associated differentially expressed genes (DEGs) may be candidates for distinctive markers for pancreatic cancer. This study aimed to evaluate the possibility of MTV-related DEGs as markers or therapeutic targets for pancreatic cancer.

METHODS

Tumor tissues and their normal counterparts were obtained from patients undergoing preoperative 18F-FDG PET/CT. The tissues were classified into MTV-low and MTV-high groups (7 for each) based on the MTV2.5 value of 4.5 (MTV-low: MTV2.5 < 4.5, MTV-high: MTV2.5 ≥ 4.5). Gene expression fold change was first calculated in cancer tissue compared to its normal counter and then compared between low and high MTV groups to obtain significant DEGs. To assess the suitability of the DEGs for clinical application, the correlation of the DEGs with tumor grades and clinical outcomes was analyzed in TCGA-PAAD, a large dataset without MTV information.

RESULTS

Total RNA-sequencing (MTV RNA-Seq) revealed that 44 genes were upregulated and 56 were downregulated in the high MTV group. We selected the 29 genes matching MTV RNA-seq patterns in the TCGA-PAAD dataset, a large clinical dataset without MTV information, as MTV-associated genes (MAGs). In the analysis with the TCGA dataset, MAGs were significantly associated with patient survival, treatment outcomes, TCGA-PAAD-suggested markers, and CEACAM family proteins. Some MAGs showed an inverse correlation with miRNAs and were confirmed to be differentially expressed between normal and cancerous pancreatic tissues. Overexpression of KIF11 and RCC1 and underexpression of ADCY1 and SDK1 were detected in ~ 60% of grade 2 pancreatic cancer patients and associated with ~ 60% mortality in stages I and II.

CONCLUSIONS

MAGs may serve as diagnostic markers and miRNA therapeutic targets for pancreatic cancer. Among the MAGs, KIF11, RCC1, ADCY, and SDK1 may be early diagnostic markers.

Mechanisms of lipopolysaccharide protection in tumor drug-induced macrophage damage

Malignant tumors contribute significantly to human mortality. Chemotherapy is a commonly used treatment for tumors. However, due to the low selectivity of chemotherapeutic drugs, immune cells can be damaged during antitumor treatment, resulting in toxicity. Lipopolysaccharide (LPS) can stimulate immune cells to respond to foreign substances. Here, we found that 10 ng/mL LPS could induce tolerance to antitumor drugs in macrophages without altering the effect of the drugs on tumor cells. Differentially expressed genes (DEGs) were identified between cells before and after LPS administration using transcriptome sequencing and found to be mainly associated with ATP-binding cassette (ABC)-resistant transporters and glutathione S-transferase (GST). LPS was shown by qRT-PCR and western blotting to promote the expression of ABCC1, GSTT1, and GSTP1 by 38.3 %, 194.8 %, and 27.0 %. Furthermore, three inhibitors (inhibitors of GST, glutathione synthesis, and ABCC1) were used for further investigation, showing that these inhibitors reduced macrophage survival rates by 44.0 %, 52.3 %, and 43.3 %, while the intracellular adriamycin content increased by 28.9 %, 42.9 %, and 51.3 %, respectively. These findings suggest that the protective mechanism of LPS on macrophages is associated with increased GST activity, the consumption of glutathione, and increased expression of ABCC1 protein. Therefore, LPS has a potential role in enhancing immunity.

Advancing 6-bromo-7-[11C]methylpurine to clinical use: improved regioselective radiosynthesis, non-clinical toxicity data and human dosimetry estimates

BACKGROUND

6-Bromo-7-[11C]methylpurine ([11C]BMP) is a radiotracer for positron emission tomography (PET) to measure multidrug resistance-associated protein 1 (MRP1) transport activity in different tissues. Previously reported radiosyntheses of [11C]BMP afforded a mixture of 7- and 9-[11C]methyl regioisomers. To prepare for clinical use, we here report an improved regioselective radiosynthesis of [11C]BMP, the results of a non-clinical toxicity study as well as human dosimetry estimates based on mouse PET data.

RESULTS

[11C]BMP was synthesised by regioselective N7-methylation of 6-bromo-7H-purine (prepared under good manufacturing practice) with [11C]methyl triflate in presence of 2,2,6,6-tetramethylpiperidine magnesium chloride in a TRACERlab™ FX2 C synthesis module. [11C]BMP was obtained within a total synthesis time of approximately 43 min in a decay-corrected radiochemical yield of 20.5 ± 5.2%, based on starting [11C]methyl iodide, with a radiochemical purity > 99% and a molar activity at end of synthesis of 197 ± 130 GBq/μmol (n = 28). An extended single-dose toxicity study conducted in male and female Wistar rats under good laboratory practice after single intravenous (i.v.) administration of unlabelled BMP (2 mg/kg body weight) revealed no test item related adverse effects. Human dosimetry estimates, based on dynamic whole-body PET data in female C57BL/6J mice, suggested that an i.v. injected activity amount of 400 MBq of [11C]BMP will deliver an effective dose in the typical range of 11C-labelled radiotracers.

CONCLUSIONS

[11C]BMP can be produced in sufficient amounts and acceptable quality for clinical use. Data from the non-clinical safety evaluation showed no adverse effects and suggested that the administration of [11C]BMP will be safe and well tolerated in humans.

Emerging Role of ABC Transporters in Glia Cells in Health and Diseases of the Central Nervous System

ATP-binding cassette (ABC) transporters play a crucial role for the efflux of a wide range of substrates across different cellular membranes. In the central nervous system (CNS), ABC transporters have recently gathered significant attention due to their pivotal involvement in brain physiology and neurodegenerative disorders, such as Alzheimer's disease (AD). Glial cells are fundamental for normal CNS function and engage with several ABC transporters in different ways. Here, we specifically highlight ABC transporters involved in the maintenance of brain homeostasis and their implications in its metabolic regulation. We also show new aspects related to ABC transporter function found in less recognized diseases, such as Huntington's disease (HD) and experimental autoimmune encephalomyelitis (EAE), as a model for multiple sclerosis (MS). Understanding both their impact on the physiological regulation of the CNS and their roles in brain diseases holds promise for uncovering new therapeutic options. Further investigations and preclinical studies are warranted to elucidate the complex interplay between glial ABC transporters and physiological brain functions, potentially leading to effective therapeutic interventions also for rare CNS disorders.

Sex-specific changes in protein expression of membrane transporters in the brain cortex of 5xFAD mouse model of Alzheimer's disease

Membrane transporters playing an important role in the passage of drugs, metabolites and nutrients across the membranes of the brain cells have been shown to be involved in pathogenesis of Alzheimer's disease (AD). However, little is known about sex-specific changes in transporter protein expression at the brain in AD. Here, we investigated sex-specific alterations in protein expression of three ATP-binding cassette (ABC) and five solute carriers (SLC) transporters in the prefrontal cortex of a commonly used model of familial AD (FAD), 5xFAD mice. Sensitive liquid chromatography tandem mass spectrometry-based quantitative targeted absolute proteomic analysis was applied for absolute quantification of transporter protein expression. We compared the changes in transporter protein expressions in 7-month-old male and female 5xFAD mice versus sex-matched wild-type mice. The study revealed a significant sex-specific increase in protein expression of ABCC1 (p = 0.007) only in male 5xFAD mice as compared to sex-matched wild-type animals. In addition, the increased protein expression of glucose transporter 1 (p = 0.01), 4F2 cell-surface antigen heavy chain (p = 0.01) and long-chain fatty acid transport protein 1 (p = 0.02) were found only in female 5xFAD mice as compared to sex-matched wild-type animals. Finally, protein expression of alanine/serine/cysteine/threonine transporter 1 was upregulated in both male (p = 0.02) and female (p = 0.002) 5xFAD mice. The study provides important information about sex-specific changes in brain cortical transporter expression in 5xFAD mice, which will facilitate drug development of therapeutic strategies for AD targeting these transporters and drug delivery research.

IGF2BP2 modulates autophagy and serves as a prognostic marker in glioma

Glioma, a malignant brain tumor originating from neural glial cells, presents significant treatment challenges. However, the underlying mechanisms of glioma development are not fully understood, and effective targets are lacking. This study provides insights into the role of insulin-like growth factor 2 messenger RNA-binding protein 2 (IGF2BP2) in glioma progression and its therapeutic potential. Our analysis illustrated that elevated IGF2BP2 expression associated with significantly shorter survival among patients with low-grade glioma (LGG) in The Cancer Genome Atlas (TCGA) database. IGF2BP2 depletion led to compromised cell viability, G0/G1 phase arrest, and reduced colony-formation ability. Furthermore, ultrastructural analysis and mCherry-GFP-LC3 reporter assay revealed an increased abundance of autophagosomes upon IGF2BP2 knockdown. Western blot analysis corroborated these findings by showing reduced p62 levels coupled with increased LC3-ІІ/LC3-I ratio upon IGF2BP2 knockdown. A multicolor immunohistochemistry assay demonstrated the positive correlation between IGF2BP2 and p62 expression in glioma patient samples. Additionally, our analysis suggested a link between IGF2BP2 expression and drug-resistant markers in TCGA-LGG samples, and Cell Counting Kit-8 cell viability assay revealed that knockdown of IGF2BP2 sensitized cells to temozolomide treatment. This comprehensive exploration unveils the role of IGF2BP2 in glioma progression, shedding light on autophagy modulation and chemosensitization strategies for glioma therapy.

Structural basis for the modulation of MRP2 activity by phosphorylation and drugs

Multidrug resistance-associated protein 2 (MRP2/ABCC2) is a polyspecific efflux transporter of organic anions expressed in hepatocyte canalicular membranes. MRP2 dysfunction, in Dubin-Johnson syndrome or by off-target inhibition, for example by the uricosuric drug probenecid, elevates circulating bilirubin glucuronide and is a cause of jaundice. Here, we determine the cryo-EM structure of rat Mrp2 (rMrp2) in an autoinhibited state and in complex with probenecid. The autoinhibited state exhibits an unusual conformation for this class of transporter in which the regulatory domain is folded within the transmembrane domain cavity. In vitro phosphorylation, mass spectrometry and transport assays show that phosphorylation of the regulatory domain relieves this autoinhibition and enhances rMrp2 transport activity. The in vitro data is confirmed in human hepatocyte-like cells, in which inhibition of endogenous kinases also reduces human MRP2 transport activity. The drug-bound state reveals two probenecid binding sites that suggest a dynamic interplay with autoinhibition. Mapping of the Dubin-Johnson mutations onto the rodent structure indicates that many may interfere with the transition between conformational states.

Utilizing non-coding RNA-mediated regulation of ATP binding cassette (ABC) transporters to overcome multidrug resistance to cancer chemotherapy

Multidrug resistance (MDR) is one of the primary factors that produces treatment failure in patients receiving cancer chemotherapy. MDR is a complex multifactorial phenomenon, characterized by a decrease or abrogation of the efficacy of a wide spectrum of anticancer drugs that are structurally and mechanistically distinct. The overexpression of the ATP-binding cassette (ABC) transporters, notably ABCG2 and ABCB1, are one of the primary mediators of MDR in cancer cells, which promotes the efflux of certain chemotherapeutic drugs from cancer cells, thereby decreasing or abolishing their therapeutic efficacy. A number of studies have suggested that non-coding RNAs (ncRNAs), particularly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), play a pivotal role in mediating the upregulation of ABC transporters in certain MDR cancer cells. This review will provide updated information about the induction of ABC transporters due to the aberrant regulation of ncRNAs in cancer cells. We will also discuss the measurement and biological profile of circulating ncRNAs in various body fluids as potential biomarkers for predicting the response of cancer patients to chemotherapy. Sequence variations, such as alternative polyadenylation of mRNA and single nucleotide polymorphism (SNPs) at miRNA target sites, which may indicate the interaction of miRNA-mediated gene regulation with genetic variations to modulate the MDR phenotype, will be reviewed. Finally, we will highlight novel strategies that could be used to modulate ncRNAs and circumvent ABC transporter-mediated MDR.

Single-cell RNA sequencing of mid-to-late stage spider embryos: new insights into spider development

BACKGROUND

The common house spider Parasteatoda tepidariorum represents an emerging new model organism of arthropod evolutionary and developmental (EvoDevo) studies. Recent technical advances have resulted in the first single-cell sequencing (SCS) data on this species allowing deeper insights to be gained into its early development, but mid-to-late stage embryos were not included in these pioneering studies.

RESULTS

Therefore, we performed SCS on mid-to-late stage embryos of Parasteatoda and characterized resulting cell clusters by means of in-silico analysis (comparison of key markers of each cluster with previously published information on these genes). In-silico prediction of the nature of each cluster was then tested/verified by means of additional in-situ hybridization experiments with additional markers of each cluster.

CONCLUSIONS

Our data show that SCS data reliably group cells with similar genetic fingerprints into more or less distinct clusters, and thus allows identification of developing cell types on a broader level, such as the distinction of ectodermal, mesodermal and endodermal cell lineages, as well as the identification of distinct developing tissues such as subtypes of nervous tissue cells, the developing heart, or the ventral sulcus (VS). In comparison with recent other SCS studies on the same species, our data represent later developmental stages, and thus provide insights into different stages of developing cell types and tissues such as differentiating neurons and the VS that are only present at these later stages.

Blood-brain barrier transporters: An overview of function, dysfunction in Alzheimer's disease and strategies for treatment

The blood-brain-barrier (BBB) has a major function in maintaining brain homeostasis by regulating the entry of molecules from the blood to the brain. Key players in BBB function are BBB transporters which are highly expressed in brain endothelial cells (BECs) and critical in mediating the exchange of nutrients and waste products. BBB transporters can also influence drug delivery into the brain by inhibiting or facilitating the entry of brain targeting therapeutics for the treatment of brain disorders, such as Alzheimer's disease (AD). Recent studies have shown that AD is associated with a disrupted BBB and transporter dysfunction, although their roles in the development in AD are not fully understand. Modulation of BBB transporter activity may pose a novel approach to enhance the delivery of drugs to the brain for enhanced treatment of AD. In this review, we will give an overview of key functions of BBB transporters and known changes in AD. In addition, we will discuss current strategies for transporter modulation for enhanced drug delivery into the brain.

Emerging roles of ncRNAs regulating ABCC1 on chemotherapy resistance of cancer - a review

In the process of chemotherapy, drug resistance of cancer cells is a common and difficult problem of chemotherapy failure, and it is also the main cause of cancer recurrence and metastasis. Non-coding RNAs (ncRNAs) refer to the RNA that does not encode proteins, including microRNA (miRNA), long non-coding RNA (lncRNA) and circularRNA (circRNA), etc. NcRNAs are involved in a series of important life processes and further regulate the expression of ABCC1 by directly or indirectly up-regulating or down-regulating the expression of targeted mRNAs, making cancer cells more susceptible to drug resistance. A growing number of studies have shown that ncRNAs have effects on cancer cell proliferation, invasion, metastasis, and drug sensitivity, by regulating the expression of ABCC1. In this review, we will discuss the emerging roles of ncRNAs regulating ABCC1 in chemotherapy resistance and mechanisms to reverse drug resistance as well as provide potential targets for future cancer treatment.

Cell-to-cell communications of cGAS-STING pathway in tumor immune microenvironment

Targeting cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway is a promising strategy for tumor treatment. The pattern recognition receptor cGAS identifies dsDNA and catalyzes the formation of a second messenger 2'3'-cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), activating the downstream interferons and pro-inflammatory cytokines through the adaptor protein STING. Notably, in tumor immune microenvironment, key components of cGAS-STING pathway are transferred among neighboring cells. The intercellular transmission under these contexts serves to sustain and amplify innate immune responses while facilitating the emergence of adaptive immunity. The membrane-based system, including extracellular vesicles transport, phagocytosis and membrane fusion transmit dsDNA, cGAMP and activated STING, enhances the immune surveillance and inflammatory responses. The membrane proteins, including a specific protein channel and intercellular gap junctions, transfer cGAMP and dsDNA, which are crucial to regulate immune responses. The ligand-receptor interactions for interferon transmission amplifies the anti-tumor response. This review elaborates on the regulatory mechanisms of cell-to-cell communications of cGAS-STING pathway in tumor immune microenvironment, explores how these mechanisms modulate immunological processes and discusses potential interventions and immunotherapeutic strategies targeting these signaling cascades.

Novel Insights on Ferroptosis Modulation as Potential Strategy for Cancer Treatment: When Nature Kills

Significance: The multifactorial nature of the mechanisms implicated in cancer development still represents a major issue for the success of established antitumor therapies. The discovery of ferroptosis, a novel form of programmed cell death distinct from apoptosis, along with the identification of the molecular pathways activated during its execution, has led to the uncovering of novel molecules characterized by ferroptosis-inducing properties. Recent advances: As of today, the ferroptosis-inducing properties of compounds derived from natural sources have been investigated and interesting findings have been reported both in vitro and in vivo. Critical Issues: Despite the efforts made so far, only a limited number of synthetic compounds have been identified as ferroptosis inducers, and their utilization is still limited to basic research. In this review, we analyzed the most important biochemical pathways involved in ferroptosis execution, with particular attention to the newest literature findings on canonical and non-canonical hallmarks, together with mechanisms of action of natural compounds identified as novel ferroptosis inducers. Compounds have been classified based on their chemical structure, and modulation of ferroptosis-related biochemical pathways has been reported. Future Directions: The outcomes herein collected represent a fascinating starting point from which to take hints for future drug discovery studies aimed at identifying ferroptosis-inducing natural compounds for anticancer therapies. Antioxid. Redox Signal. 40, 40-85.

Targeting altered calcium homeostasis and uncoupling protein-2 promotes sensitivity in drug-resistant breast cancer cells

Metastatic breast cancer has the highest mortality rate among women owing to its poor clinical outcomes. Metastatic tumors pose challenges for treatment through conventional surgery or radiotherapy because of their diverse organ localization and resistance to various cytotoxic agents. Chemoresistance is a significant obstacle to effective breast cancer treatment owing to cancer's heterogeneous nature. Abnormalities in intracellular calcium signaling, coupled with altered mitochondrial metabolism, play a significant role in facilitating drug resistance and contribute to therapy resistance. Uncoupling protein-2 (UCP2) is considered as a marker of chemoresistance and is believed to play a major role in promoting metabolic shifts and tumor metastasis. In this context, it is imperative to understand the roles of altered calcium signaling and metabolic switching in the development of chemotherapeutic resistance. This study investigates the roles of UCP2 and intracellular calcium signaling (Ca2+ ) in promoting chemoresistance against cisplatin. Additionally, we explored the effectiveness of combining genipin (GP, a compound that reverses UCP2-mediated chemoresistance) and thapsigargin (TG, a calcium signaling modulator) in treating highly metastatic breast cancers. Our findings indicate that both aberrant Ca2+ signaling and metabolic shifts in cancer cells contribute to developing drug-resistant phenotypes, and the combination treatment of GP and TG significantly enhances drug sensitivity in these cells. Collectively, our study underscores the potential of these drug combinations as an effective approach to overcome drug resistance in chemoresistant cancers.

Modulation of Multidrug Resistance Protein 1-mediated Transport Processes by the Antiviral Drug Ritonavir in Cultured Primary Astrocytes

The Multidrug Resistance Protein 1 (Mrp1) is an ATP-dependent efflux transporter and a major facilitator of drug resistance in mammalian cells during cancer and HIV therapy. In brain, Mrp1-mediated GSH export from astrocytes is the first step in the supply of GSH precursors to neurons. To reveal potential mechanisms underlying the drug-induced modulation of Mrp1-mediated transport processes, we investigated the effects of the antiviral drug ritonavir on cultured rat primary astrocytes. Ritonavir strongly stimulated the Mrp1-mediated export of glutathione (GSH) by decreasing the Km value from 200 nmol/mg to 28 nmol/mg. In contrast, ritonavir decreased the export of the other Mrp1 substrates glutathione disulfide (GSSG) and bimane-glutathione. To give explanation for these apparently contradictory observations, we performed in silico docking analysis and molecular dynamics simulations using a homology model of rat Mrp1 to predict the binding modes of ritonavir, GSH and GSSG to Mrp1. The results suggest that ritonavir binds to the hydrophilic part of the bipartite binding site of Mrp1 and thereby differently affects the binding and transport of the Mrp1 substrates. These new insights into the modulation of Mrp1-mediated export processes by ritonavir provide a new model to better understand GSH-dependent detoxification processes in brain cells.

RAD54L2-mediated DNA damage avoidance pathway specifically preserves genome integrity in response to topoisomerase 2 poisons

Type II topoisomerases (TOP2) form transient TOP2 cleavage complexes (TOP2ccs) during their catalytic cycle to relieve topological stress. TOP2ccs are covalently linked TOP2-DNA intermediates that are reversible but can be trapped by TOP2 poisons. Trapped TOP2ccs block transactions on DNA and generate genotoxic stress, which are the mechanisms of action of TOP2 poisons. How cells avoid TOP2cc accumulation remains largely unknown. In this study, we uncovered RAD54 like 2 (RAD54L2) as a key factor that mediates a TOP2-specific DNA damage avoidance pathway. RAD54L2 deficiency conferred unique sensitivity to treatment with TOP2 poisons. RAD54L2 interacted with TOP2A/TOP2B and ZATT/ZNF451 and promoted the turnover of TOP2 from DNA with or without TOP2 poisons. Additionally, inhibition of proteasome activity enhanced the chromatin binding of RAD54L2, which in turn led to the removal of TOP2 from chromatin. In conclusion, we propose that RAD54L2-mediated TOP2 turnover is critically important for the avoidance of potential TOP2-linked DNA damage under physiological conditions and in response to TOP2 poisons.

The role of ATP binding cassette (ABC) transporters in breast cancer: Evaluating prognosis, predicting immunity, and guiding treatment

Breast cancer is currently the most prevalent form of cancer worldwide. Nevertheless, there remains limited clarity regarding our understanding of the tumor microenvironment and metabolic characteristics associated with it. ATP-binding cassette (ABC) transporters are the predominant transmembrane transporters found in organisms. Therefore, it is essential to investigate the role of ABC transporters in breast cancer. Transcriptome data from breast cancer patients were downloaded from the TCGA database. ABC transporter-related genes were obtained from the Genecards database. By LASSO regression, ABC-associated prognostic signature was constructed in breast cancer. Subsequently, immune microenvironment analysis was performed. Finally, cell experiments were performed to verify the function of ABCB7 in the breast cancer cell lines MDA-MB-231 and MCF-7. Using the ABC transporter-associated signature, we calculated a risk score for each breast cancer patient. Patients with breast cancer were subsequently categorized into high-risk and low-risk groups, utilizing the median risk score as the threshold. Notably, patients in the high-risk group exhibited significantly worse prognosis (P<0.05). Additionally, differences were observed in terms of immune cell infiltration levels, immune correlations, and gene expression of immune checkpoints between the two groups. Functional experiments conducted on breast cancer cell lines MDA-MB-231 and MCF-7 demonstrated that ABCB7 knockdown significantly diminished cell activity, proliferation, invasion, and migration. These findings emphasize the significance of understanding ABC transporter-mediated metabolic and transport characteristics in breast cancer, offering promising directions for further research and potential therapeutic interventions.

Single Live Cell Imaging of Multidrug Resistance Using Silver Ultrasmall Nanoparticles as Biosensing Probes in Triple-Negative Breast Cancer Cells

Silver ultrasmall nanoparticles (Ag UNPs) (size < 5 nm) were used as biosensing probes to analyze the efflux kinetics contributing to multidrug resistance (MDR) in single live triple-negative breast cancer (TNBC) cells by using dark-field optical microscopy to follow their size-dependent localized surface plasmon resonance. TNBC cells lack expression of estrogen (ER-), progesterone (PR-), and human epidermal growth factor 2 (HER2-) receptors and are more likely to acquire resistance to anticancer drugs due to their ability to transport harmful substances outside the cell. The TNBC cells displayed greater nuclear and cytoplasmic efflux, resulting in less toxicity of Ag UNPs in a concentration-independent manner. In contrast, more Ag UNPs and an increase in cytotoxic effects were observed in the receptor-positive breast cancer cells that have receptors for ER+, PR+, and HER2+ and are known to better respond to anticancer therapies. Ag UNPs accumulated in receptor-positive breast cancer cells in a time-and concentration-dependent mode and caused decreased cellular growth, whereas the TNBC cells due to the efflux were able to continue to grow. The TNBC cells demonstrated a marked increase in survival due to their ability to have MDR determined by efflux of Ag UNPs outside the nucleus and the cytoplasm of the cells. Further evaluation of the nuclear efflux kinetics of TNBC cells with Ag UNPs as biosensing probes is critical to gain a better understanding of MDR and potential for enhancement of cancer drug delivery.

The mechanisms of multidrug resistance of breast cancer and research progress on related reversal agents

Chemotherapy is the mainstay in the treatment of breast cancer. However, many drugs that are commonly used in clinical practice have a high incidence of side effects and multidrug resistance (MDR), which is mainly caused by overexpression of drug transporters and related enzymes in breast cancer cells. In recent years, researchers have been working hard to find newer and safer drugs to overcome MDR in breast cancer. In this review, we provide the molecule mechanism of MDR in breast cancer, categorize potential lead compounds that inhibit single or multiple drug transporter proteins, as well as related enzymes. Additionally, we have summarized the structure-activity relationship (SAR) based on potential breast cancer MDR modulators with lower side effects. The development of novel approaches to suppress MDR is also addressed. These lead compounds hold great promise for exploring effective chemotherapy agents to overcome MDR, providing opportunities for curing breast cancer in the future.

Targeting Glucose Metabolism in Cancer Cells as an Approach to Overcoming Drug Resistance

The "Warburg effect" consists of a metabolic shift in energy production from oxidative phosphorylation to glycolysis. The continuous activation of glycolysis in cancer cells causes rapid energy production and an increase in lactate, leading to the acidification of the tumour microenvironment, chemo- and radioresistance, as well as poor patient survival. Nevertheless, the mitochondrial metabolism can be also involved in aggressive cancer characteristics. The metabolic differences between cancer and normal tissues can be considered the Achilles heel of cancer, offering a strategy for new therapies. One of the main causes of treatment resistance consists of the increased expression of efflux pumps, and multidrug resistance (MDR) proteins, which are able to export chemotherapeutics out of the cell. Cells expressing MDR proteins require ATP to mediate the efflux of their drug substrates. Thus, inhibition of the main energy-producing pathways in cancer cells, not only induces cancer cell death per se, but also overcomes multidrug resistance. Given that most anticancer drugs do not have the ability to distinguish normal cells from cancer cells, a number of drug delivery systems have been developed. These nanodrug delivery systems provide flexible and effective methods to overcome MDR by facilitating cellular uptake, increasing drug accumulation, reducing drug efflux, improving targeted drug delivery, co-administering synergistic agents, and increasing the half-life of drugs in circulation.

Cancer chemotherapy resistance: Mechanisms and recent breakthrough in targeted drug delivery

Conventional chemotherapy, one of the most widely used cancer treatment methods, has serious side effects, and usually results in cancer treatment failure. Drug resistance is one of the primary reasons for this failure. The most significant drawbacks of systemic chemotherapy are rapid clearance from the circulation, the drug's low concentration in the tumor site, and considerable adverse effects outside the tumor. Several ways have been developed to boost neoplasm treatment efficacy and overcome medication resistance. In recent years, targeted drug delivery has become an essential therapeutic application. As more mechanisms of tumor treatment resistance are discovered, nanoparticles (NPs) are designed to target these pathways. Therefore, understanding the limitations and challenges of this technology is critical for nanocarrier evaluation. Nano-drugs have been increasingly employed in medicine, incorporating therapeutic applications for more precise and effective tumor diagnosis, therapy, and targeting. Many benefits of NP-based drug delivery systems in cancer treatment have been proven, including good pharmacokinetics, tumor cell-specific targeting, decreased side effects, and lessened drug resistance. As more mechanisms of tumor treatment resistance are discovered, NPs are designed to target these pathways. At the moment, this innovative technology has the potential to bring fresh insights into cancer therapy. Therefore, understanding the limitations and challenges of this technology is critical for nanocarrier evaluation.

Advances in the structure, mechanism and targeting of chemoresistance-linked ABC transporters

Cancer cells frequently display intrinsic or acquired resistance to chemically diverse anticancer drugs, limiting therapeutic success. Among the main mechanisms of this multidrug resistance is the overexpression of ATP-binding cassette (ABC) transporters that mediate drug efflux, and, specifically, ABCB1, ABCG2 and ABCC1 are known to cause cancer chemoresistance. High-resolution structures, biophysical and in silico studies have led to tremendous progress in understanding the mechanism of drug transport by these ABC transporters, and several promising therapies, including irradiation-based immune and thermal therapies, and nanomedicine have been used to overcome ABC transporter-mediated cancer chemoresistance. In this Review, we highlight the progress achieved in the past 5 years on the three transporters, ABCB1, ABCG2 and ABCC1, that are known to be of clinical importance. We address the molecular basis of their broad substrate specificity gleaned from structural information and discuss novel approaches to block the function of ABC transporters. Furthermore, genetic modification of ABC transporters by CRISPR-Cas9 and approaches to re-engineer amino acid sequences to change the direction of transport from efflux to import are briefly discussed. We suggest that current information regarding the structure, mechanism and regulation of ABC transporters should be used in clinical trials to improve the efficiency of chemotherapeutics for patients with cancer.