Breast cancer resistance protein (BCRP/ABCG2): its role in multidrug resistance and regulation of its gene expression

High-throughput BCRP inhibitors screening system based on styrene maleic acid polymer membrane protein stabilization strategy and surface plasmon resonance biosensor

Multidrug resistance (MDR) is a dominant challenge in cancer chemotherapy failure. The over-expression of breast cancer resistance protein (BCRP) in tumorous cells, along with its extensive substrate profile, is a leading cause of tumor MDR. Herein, on the basis of styrene maleic acid (SMA) polymer membrane protein stabilization strategy and surface plasmon resonance (SPR) biosensor, a novel high-throughput screening (HTS) system for BCRP inhibitors has been established. Firstly, LLC-PK1 and LLC-PK1/BCRP cell membranes were co-incubated with SMA polymers to construct SMA lipid particles (SMALPs). PK1-SMALPs were thus immobilized in channel 1 of the L1 chip as the reference channel, and BCRP-SMALPs were immobilized in channel 2 as the detection channel to establish the BCRP-SMALPs-SPR screening system. The methodological investigation demonstrated that the screening system was highly specific and stable. Three active compounds were screened out from 26 natural products and their affinity constants with BCRP were determined. The KD of xanthotoxin, bergapten, and naringenin were 5.14 μM, 4.57 μM, and 3.72 μM, respectively. The in vitro cell verification experiments demonstrated that xanthotoxin, bergapten, and naringenin all significantly increased the sensitivity of LLC-PK1/BCRP cells to mitoxantrone with possessing reversal BCRP-mediated MDR activity. Collectively, the developed BCRP-SMALPs-SPR screening system in this study has the advantages of rapidity, efficiency, and specificity, providing a novel strategy for the in-depth screening of BCRP inhibitors with less side effects and higher efficacy.

Identification of novel genetic susceptibility loci for calcium-containing kidney stone disease by genome-wide association study and polygenic risk score in a Taiwanese population

Approximately 80% of kidney stone diseases contain calcium. Inherited genetic factors are among the variables that influence the development of calcium-containing kidney stone diseases (CKSD). Previous genome-wide association studies (GWAS) on stone diseases have been reported worldwide; however, these are not focused on calcium-containing stones. We conducted a GWAS to identify germline genetic polymorphisms associated with CKSD in a Medical Center in Taiwan; hence, this study was based primarily on a hospital-based database. CKSD was diagnosed using the chart records. Patients infected with urea-splitting-microorganisms and those with at least two urinary pH value below 5.5 were excluded. None of the patients had cystic stones based on stone analysis. Those over 40 years of age with no history of CKSD and no microscopic hematuria on urinalysis were considered as controls. The DNA isolated from the blood of 14,934 patients (63.7% male and 36.3% female) with CKSD and 29,868 controls (10,830 men and 19,038 women) at a medical center was genotyped for approximately 714,457 single nucleotide polymorphisms (SNPs) with minor allele frequency of ≥ 0.05. We used PLINK 1.9 to calculate the polygenic risk score (PRS) to investigate the association between CKSD and controls. The accuracy of the PRS was verified by dividing it into the training and testing groups. The statistical analyses were calculated with the area under the curve (AUC) using IBM SPSS version 22. We identified 432 susceptibility loci that reached a genome-wide threshold of P < 1.0 × 10- 5. A total of 132 SNPs reached a threshold of P < 5 × 10- 8 using a stricter definition of significance on chromosomes 4, 13, 16, 17, and 18. At the top locus of our study, SNPs in DGKH, PDILT, BCAS3, and ABCG2 have been previously reported. RN7SKP27, HDAC4, PCDH15, AP003068.2, and NFATC1 were novel findings in this study. PRS was adjusted for sex and age, resulting in an AUC of 0.65. The number of patients in the top quartile of PRS was 1.39 folds in the risk of CKSD than patients in the bottom quartile. Our data identified the significance of GWAS for patients with CKSD in a hospital-based study. The PRS also had a high AUC for discriminating patients with CKSD from controls. A total of 132 SNP loci of SNPs significantly associated with the development of CKSD. This first survey, which focused on patients with CKSD, will provide novel insights specific to CKSD and its potential clinical biomarkers.

The contradictory role of febuxostat in ABCG2 expression and potentiating hypericin-mediated photodynamic therapy in colorectal cancers

Photodynamic Therapy (PDT) is an emerging method to treat colorectal cancers (CRC). Hypericin (HYP) is an effective mediator of PDT and the ABCG2 inhibitor, Febuxostat (FBX) could augment PDT. HT29 and HEK293 cells showed light dependant cytotoxic response to PDT in both 2D and 3D cell models. FBX co-treatment was not found to improve PDT cytotoxicity. Next, ABCG2 protein expression was observed in HT29 but not in HEK293 cells. However, ABCG2 gene expression analysis did not support protein expression results as ABCG2 gene expression results were found to be higher in HEK293 cells. Although HYP treatment was found to significantly reduce ABCG2 gene expression levels in both cell lines, FBX treatment partially restored ABCG2 gene expression. Our findings indicate that FBX co-treatment may not be suitable for augmenting HYP-mediated PDT in CRC but could potentially be useful for other applications.

Enhancing of cerebral Abeta clearance by modulation of ABC transporter expression: a review of experimental approaches

Clearance of amyloid-beta (Aβ) from the brain is impaired in both early-onset and late-onset Alzheimer's disease (AD). Mechanisms for clearing cerebral Aβ include proteolytic degradation, antibody-mediated clearance, blood brain barrier and blood cerebrospinal fluid barrier efflux, glymphatic drainage, and perivascular drainage. ATP-binding cassette (ABC) transporters are membrane efflux pumps driven by ATP hydrolysis. Their functions include maintenance of brain homeostasis by removing toxic peptides and compounds, and transport of bioactive molecules including cholesterol. Some ABC transporters contribute to lowering of cerebral Aβ. Mechanisms suggested for ABC transporter-mediated lowering of brain Aβ, in addition to exporting of Aβ across the blood brain and blood cerebrospinal fluid barriers, include apolipoprotein E lipidation, microglial activation, decreased amyloidogenic processing of amyloid precursor protein, and restricting the entrance of Aβ into the brain. The ABC transporter superfamily in humans includes 49 proteins, eight of which have been suggested to reduce cerebral Aβ levels. This review discusses experimental approaches for increasing the expression of these ABC transporters, clinical applications of these approaches, changes in the expression and/or activity of these transporters in AD and transgenic mouse models of AD, and findings in the few clinical trials which have examined the effects of these approaches in patients with AD or mild cognitive impairment. The possibility that therapeutic upregulation of ABC transporters which promote clearance of cerebral Aβ may slow the clinical progression of AD merits further consideration.

GALNT14 in association with GDF-15 promotes stemness and drug resistance through β-catenin signalling pathway in breast cancer

BACKGROUND

Altered glycosylation plays a role in carcinogenesis. GALNT14 promotes cancer stem-like properties and drug resistance. GDF-15 is known to induces drug resistance and stemness markers for maintenance of breast cancer (BC) stem-like cell state. Currently there is lack of data on association of GDF-15 and GALNTs. In this study, the expression and interaction of GALNT14 and GDF-15 with stemness (OCT4 and SOX2) and drug resistance (ABCC5) markers were evaluated in BC.

METHODS

We investigated tumour tissue from 30 BC patients and adjacent non-tumour tissues. Expression of serum GALNT14 from BC patients and matched healthy controls was evaluated. Expression of GALNT14, GDF-15, OCT4, SOX2, ABCC5, and β-catenin in BC tissue was determined by RT-PCR. Knockdown of GALNT14 and GDF-15 in the MCF-7 cell line was done through siRNA, gene expression and protein expression of β-catenin by western blot were determined.

RESULTS

A significant increase in the expression of GALNT14, GDF-15, OCT4, SOX2, ABCC5, and β-catenin was observed in BC tumour tissues compared to adjacent non-tumour tissues. The serum level of GALNT14 was significantly high in BC patients (80.7 ± 65.3 pg/ml) compared to healthy controls (12.2 ± 9.12 pg/ml) (p < 0.000). To further analyse the signalling pathway involved in BC stemness and drug resistance, GALNT14 and GDF-15 were knocked down in the MCF-7 cell line, and it was observed that after knockdown, the expression level of OCT4, SOX2, ABCC5, and β-catenin was decreased, and co-knockdown with GALNT14 and GDF-15 further decreased the expression of genes.

CONCLUSION

It can be concluded that GALNT14, in association with GDF-15, promotes stemness and intrinsic drug resistance in BC, possibly through the β-catenin signalling pathway.

Schiff bases and their metal complexes to target and overcome (multidrug) resistance in cancer

Overcoming multidrug resistance (MDR) is one of the major challenges in cancer therapy. In this respect, Schiff base-related compounds (bearing a R1R2CNR3 bond) gained high interest during the past decades. Schiff bases are considered privileged ligands for various reasons, including the easiness of their preparation and the possibility to form complexes with almost all transition metal ions. Schiff bases and their metal complexes exhibit many types of biological activities and are used for the treatment and diagnosis of various diseases. Until now, 13 Schiff bases have been investigated in clinical trials for cancer treatment and hypoxia imaging. This review represents the first collection of Schiff bases and their complexes which demonstrated MDR-reversal activity. The areas of drug resistance covered in this article involve: 1) Modulation of ABC transporter function, 2) Targeting lysosomal ABCB1 overexpression, 3) Circumvention of ABC transporter-mediated drug efflux by alternative routes of drug uptake, 4) Selective activity against MDR cancer models (collateral sensitivity), 5) Targeting GSH-detoxifying systems, 6) Overcoming apoptosis resistance by inducing necrosis and paraptosis, 7) Reactivation of mutated p53, 8) Restoration of sensitivity to DNA-damaging anticancer therapy, and 9) Overcoming drug resistance through modulation of the immune system. Through this approach, we would like to draw attention to Schiff bases and their metal complexes representing highly interesting anticancer drug candidates with the ability to overcome MDR.

Factors Influencing Mortality in Children with Central Nervous System Tumors: A Cohort Study on Clinical Characteristics and Genetic Markers

Multidrug resistance (MDR) commonly leads to cancer treatment failure because cancer cells often expel chemotherapeutic drugs using ATP-binding cassette (ABC) transporters, which reduce drug levels within the cells. This study investigated the clinical characteristics and single nucleotide variant (SNV) in ABCB1, ABCC1, ABCC2, ABCC4, and ABCG2, and their association with mortality in pediatric patients with central nervous system tumors (CNST). Using TaqMan probes, a real-time polymerase chain reaction genotyped 15 SNPs in 111 samples. Patients were followed up until death or the last follow-up day using the Cox proportional hazards model. An association was found between the rs1045642 (ABCB1) in the recessive model (HR = 2.433, 95% CI 1.098-5.392, p = 0.029), and the ICE scheme in the codominant model (HR = 9.810, 95% CI 2.74-35.06, p ≤ 0.001), dominant model (HR = 6.807, 95% CI 2.87-16.103, p ≤ 0.001), and recessive model (HR = 6.903, 95% CI 2.915-16.544, p = 0.038) significantly increased mortality in this cohort of patients. An association was also observed between the variant rs3114020 (ABCG2) and mortality in the codominant model (HR = 5.35, 95% CI 1.83-15.39, p = 0.002) and the dominant model (HR = 4.421, 95% CI 1.747-11.185, p = 0.002). A significant association between the ICE treatment schedule and increased mortality risk in the codominant model (HR = 6.351, 95% CI 1.831-22.02, p = 0.004, HR = 9.571, 95% CI 2.856-32.07, p ≤ 0.001), dominant model (HR = 6.592, 95% CI 2.669-16.280, p ≤ 0.001), and recessive model (HR = 5.798, 95% CI 2.411-13.940, p ≤ 0.001). The genetic variants rs3114020 in the ABCG2 gene and rs1045642 in the ABCB1 gene and the ICE chemotherapy schedule were associated with an increased mortality risk in this cohort of pediatric patients with CNST.

NAT10-mediated mRNA N4-acetylcytidine modification of MDR1 and BCRP promotes breast cancer progression

BACKGROUND

N-acetyltransferase 10 (NAT10) serves as a critical enzyme in mediating the N4-acetylcytidine (ac4C) that ensures RNA stability and effective translation processes. The role of NAT10 in driving the advancement of breast cancer remains uninvestigated.

METHODS

We observed an increase in NAT10 expression, both at mRNA level through the analysis of the Cancer Genome Atlas (TCGA) database and at the protein level of tumor tissues from breast cancer patients. We determined that a heightened expression of NAT10 served as a predictor of an unfavorable clinical outcome. By screening the Cancer Cell Line Encyclopedia (CCLE) cell bank, this expression pattern of NAT10 was consistency found across almost all the classic breast cancer cell lines.

RESULTS

Functionally, interference of NAT10 expression exerts an inhibitory effect on proliferation and invasion of breast cancer cells. By using ac4C RNA immunoprecipitation (ac4c-RIP) and acRIP-qPCR assays, we identified a reduction of ac4C enrichment within the ATP binding cassette (ABC) transporters, multidrug resistance protein 1 (MDR1) and breast cancer resistance protein (BCRP), consequent to NAT10 suppression. Expressions of MDR1 and BCRP exhibited a positive correlation with NAT10 expression in tumor tissues, and the inhibition of NAT10 in breast cancer cells resulted in a decrease of MDR1 and BCRP expression. Therefore, the overexpressing of MDR1 and BCRP could partially rescue the adverse consequences of NAT10 depletion. In addition, we found that, remodelin, a NAT10 inhibitor, reinstated the susceptibility of capecitabine-resistant breast cancer cells to the chemotherapy, both in vitro and in vivo.

CONCLUSION

The results of our study demonstrated the essential role of NAT10-mediated ac4c-modification in breast cancer progression and provide a novel strategy for overcoming chemoresistance challenges.

Drug resistance mechanisms in cancers: Execution of pro-survival strategies

One of the quintessential challenges in cancer treatment is drug resistance. Several mechanisms of drug resistance have been described to date, and new modes of drug resistance continue to be discovered. The phenomenon of cancer drug resistance is now widespread, with approximately 90% of cancer-related deaths associated with drug resistance. Despite significant advances in the drug discovery process, the emergence of innate and acquired mechanisms of drug resistance has impeded the progress in cancer therapy. Therefore, understanding the mechanisms of drug resistance and the various pathways involved is integral to treatment modalities. In the present review, I discuss the different mechanisms of drug resistance in cancer cells, including DNA damage repair, epithelial to mesenchymal transition, inhibition of cell death, alteration of drug targets, inactivation of drugs, deregulation of cellular energetics, immune evasion, tumor-promoting inflammation, genome instability, and other contributing epigenetic factors. Furthermore, I highlight available treatment options and conclude with future directions.

Understanding Cancer's Defense against Topoisomerase-Active Drugs: A Comprehensive Review

In recent years, the emergence of cancer drug resistance has been one of the crucial tumor hallmarks that are supported by the level of genetic heterogeneity and complexities at cellular levels. Oxidative stress, immune evasion, metabolic reprogramming, overexpression of ABC transporters, and stemness are among the several key contributing molecular and cellular response mechanisms. Topo-active drugs, e.g., doxorubicin and topotecan, are clinically active and are utilized extensively against a wide variety of human tumors and often result in the development of resistance and failure to therapy. Thus, there is an urgent need for an incremental and comprehensive understanding of mechanisms of cancer drug resistance specifically in the context of topo-active drugs. This review delves into the intricate mechanistic aspects of these intracellular and extracellular topo-active drug resistance mechanisms and explores the use of potential combinatorial approaches by utilizing various topo-active drugs and inhibitors of pathways involved in drug resistance. We believe that this review will help guide basic scientists, pre-clinicians, clinicians, and policymakers toward holistic and interdisciplinary strategies that transcend resistance, renewing optimism in the ongoing battle against cancer.

Safety of teriflunomide in Chinese adult patients with relapsing multiple sclerosis: A phase IV, 24-week multicenter study

BACKGROUND

Disease-modifying therapies have been approved for the treatment of relapsing multiple sclerosis (RMS). The present study aims to examine the safety of teriflunomide in Chinese patients with RMS.

METHODS

This non-randomized, multi-center, 24-week, prospective study enrolled RMS patients with variant (c.421C>A) or wild type ABCG2 who received once-daily oral teriflunomide 14 mg. The primary endpoint was the relationship between ABCG2 polymorphisms and teriflunomide exposure over 24 weeks. Safety was assessed over the 24-week treatment with teriflunomide.

RESULTS

Eighty-two patients were assigned to variant (n = 42) and wild type groups (n = 40), respectively. Geometric mean and geometric standard deviation (SD) of pre-dose concentration (variant, 54.9 [38.0] μg/mL; wild type, 49.1 [32.0] μg/mL) and area under plasma concentration-time curve over a dosing interval (AUCtau) (variant, 1731.3 [769.0] μg∙h/mL; wild type, 1564.5 [1053.0] μg∙h/mL) values at steady state were approximately similar between the two groups. Safety profile was similar and well tolerated across variant and wild type groups in terms of rates of treatment emergent adverse events (TEAE), treatment-related TEAE, grade ≥3 TEAE, and serious adverse events (AEs). No new specific safety concerns or deaths were reported in the study.

CONCLUSION

ABCG2 polymorphisms did not affect the steady-state exposure of teriflunomide, suggesting a similar efficacy and safety profile between variant and wild type RMS patients.

REGISTRATION

NCT04410965, https://clinicaltrials.gov.

Drug repurposing: A novel strategy to target cancer stem cells and therapeutic resistance

Chemotherapy is an effortless and frequently used approach in cancer therapy. However, in most cases, it can only prolong life expectancy and does not guarantee a complete cure. Furthermore, chemotherapy is associated with severe adverse effects, one of the major complications of effective cancer therapy. In addition, newly published research outputs show that cancer stem cells are involved in cancer disease progression, drug resistance, metastasis, and recurrence and that they are functional in the trans-differentiation capacity of cancer stem cells to cancer cells in response to treatments. Novel strategies are therefore required for better management of cancer therapy. The prime approach would be to synthesize and develop novel drugs that need extensive resources, time, and endurance to be brought into therapeutic use. The subsequent approach would be to screen the anti-cancer activity of available non-cancerous drugs. This concept of repurposing non-cancer drugs as an alternative to current cancer therapy has become popular in recent years because using existing anticancer drugs has several adverse effects. Micronutrients have also been investigated for cancer therapy due to their significant anti-cancer effects with negligible or no side effects and availability in food sources. In this paper, we discuss an ideal hypothesis for screening available non-cancerous drugs with anticancer activity, with a focus on cancer stem cells and their clinical application for cancer treatment. Further, drug repurposing and the combination of micronutrients that can target both cancers and cancer stem cells may result in a better therapeutic approach leading to maximum tumor growth control.

GSK2606414 Sensitizes ABCG2-Overexpressing Multidrug-Resistant Colorectal Cancer Cells to Chemotherapeutic Drugs

Colorectal cancer is a common malignant tumor. A major factor in the high mortality rate of colorectal cancer is the emergence of multidrug resistance (MDR). Overexpression of the ABCG2 gene in cancer cells directly leads to MDR. Finding new inhibitors of ABCG2 may be an effective way to overcome drug resistance. We found that the compound GSK2606414 enhanced the sensitivity of the ABCG2 substrate to the chemotherapeutic drugs mitoxantrone and doxorubicin in ABCG2-overexpressing multidrug-resistant colorectal cancer cells by increasing their intracellular accumulation without affecting the protein expression of ABCG2. Molecular docking experiments predicted that GSK2606414 could stably bind in the drug-binding pocket of ABCG2. In conclusion, GSK2606414 can sensitize ABCG2-overexpressed multidrug-resistant colorectal cancer cells to chemotherapy drugs and can be used as a potential inhibitor of ABCG2.

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.

Redefine the role of d-α-Tocopheryl polyethylene glycol 1000 succinate on P-glycoprotein, multidrug resistance protein 1, and breast cancer resistance protein mediated cancer multidrug resistance

Cancer drug resistance is an ever-changing problem that most patients need to face in their later stages of treatment, especially the multidrug resistant (MDR) type. The drug efflux transporters, including P-glycoprotein (P-gp), multidrug resistance protein 1 (MRP1), and breast cancer resistance protein (BCRP), play the crucial roles in this sophisticated battle. In recent decades, researchers try to find potential inhibitors to impede the drug efflux function of above transporters. d-α-Tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS) is a prevalently used excipient in the formulation design. In the present study, the modulatory effects and mechanisms of vitamin E TPGS on the efflux transporters were investigated. And the cancer MDR reversing ability of vitamin E TPGS was evaluated as well. Stable-cloned transporter over-expressed cell lines were used for mechanisms study, while several types of MDR cancer cell lines were adopted as reversing evaluation models. The results exhibited that vitamin E TPGS significantly inhibited the efflux function of P-gp, MRP1, and BCRP under non-cytotoxic concentrations, but not influencing the protein expression levels. Through efflux assay and molecular docking, vitamin E TPGS was found to be an uncompetitive, non-competitive, and competitive inhibitor on chemotherapeutic drug doxorubicin efflux in P-gp, MRP1, and BCRP over-expressing cell lines, respectively. Furthermore, the basal ATPase activity of three transporters were significantly inhibited by vitamin E TPGS at 10 μM. And the cell membrane fluidity of P-gp over-expressing cell line was enhanced by 22.58% with 5 μM vitamin E TPGS treatment, compared to the parental Flp-In™-293 cell line (without P-gp). The resistance reversing ability of vitamin E TPGS was prominent in MCF-7/DOX MDR breast cancer cell line, which over-expressed P-gp, MRP1, and BCRP. These significant results suggested that vitamin E TPGS is a promising modulator on transporters mediated cancer MDR. Vitamin E TPGS is not an inert excipient, but possesses MDR-reversing pharmacological effects, and deserves a re-purposing application on the future combinatorial regimen design for MDR cancer treatment.

ABCB1 and ABCG2 Regulation at the Blood-Brain Barrier: Potential New Targets to Improve Brain Drug Delivery

The drug efflux transporters ABCB1 and ABCG2 at the blood-brain barrier limit the delivery of drugs into the brain. Strategies to overcome ABCB1/ABCG2 have been largely unsuccessful, which poses a tremendous clinical problem to successfully treat central nervous system (CNS) diseases. Understanding basic transporter biology, including intracellular regulation mechanisms that control these transporters, is critical to solving this clinical problem.In this comprehensive review, we summarize current knowledge on signaling pathways that regulate ABCB1/ABCG2 at the blood-brain barrier. In Section I, we give a historical overview on blood-brain barrier research and introduce the role that ABCB1 and ABCG2 play in this context. In Section II, we summarize the most important strategies that have been tested to overcome the ABCB1/ABCG2 efflux system at the blood-brain barrier. In Section III, the main component of this review, we provide detailed information on the signaling pathways that have been identified to control ABCB1/ABCG2 at the blood-brain barrier and their potential clinical relevance. This is followed by Section IV, where we explain the clinical implications of ABCB1/ABCG2 regulation in the context of CNS disease. Lastly, in Section V, we conclude by highlighting examples of how transporter regulation could be targeted for therapeutic purposes in the clinic. SIGNIFICANCE STATEMENT: The ABCB1/ABCG2 drug efflux system at the blood-brain barrier poses a significant problem to successful drug delivery to the brain. The article reviews signaling pathways that regulate blood-brain barrier ABCB1/ABCG2 and could potentially be targeted for therapeutic purposes.

Clinical outcomes of chemotherapy in cancer patients with different ethnicities

BACKGROUND

Choosing the most effective chemotherapeutic agent with safest side effect profile is a common challenge in cancer treatment. Although there are standardized chemotherapy protocols in place, protocol changes made after extensive clinical trials demonstrate significant improvement in the efficacy and tolerability of certain drugs. The pharmacokinetics, pharmacodynamics, and tolerance of anti-cancer medications are all highly individualized. A driving force behind these differences lies within a person's genetic makeup.

RECENT FINDINGS

Pharmacogenomics, the study of how an individual's genes impact the processing and action of a drug, can optimize drug responsiveness and reduce toxicities by creating a customized medication regimen. However, these differences are rarely considered in the initial determination of standardized chemotherapeutic protocols and treatment algorithms. Because pharmacoethnicity is influenced by both genetic and nongenetic variables, clinical data highlighting disparities in the frequency of polymorphisms between different ethnicities is steadily growing.  Recent data suggests that ethnic variations in the expression of allelic variants may result in different pharmacokinetic properties of the anti-cancer medication. In this article, the clinical outcomes of various chemotherapy classes in patients of different ethnicities were reviewed.

CONCLUSION

Genetic and nongenetic variables contribute to the interindividual variability in response to chemotherapeutic drugs. Considering pharmacoethnicity in the initial determination of standard chemotherapeutic protocols and treatment algorithms can lead to better clinical outcomes of patients of different ethnicities.

Genome-Wide Association Study to Identify QTL for Carcass Traits in Korean Hanwoo Cattle

This study aimed to identify genetic associations with carcass traits in Hanwoo cattle using a genome-wide association study. A total of 9302 phenotypes were analyzed, and all animals were genotyped using the Illumina Bovine 50K v.3 SNP chip. Heritabilities for carcass weight (CWT), eye muscle area (EMA), backfat thickness (BF), and marbling score (MS) were estimated as 0.42, 0.36, 0.36, and 0.47, respectively, using the GBLUP model, and 0.47, 0.37, 0.36, and 0.42, respectively, using the Bayes B model. We identified 129 common SNPs using DGEBV and 118 common SNPs using GEBV on BTA6, BTA13, and BTA14, suggesting their potential association with the traits of interest. No common SNPs were found between the GBLUP and Bayes B methods when using residuals as a response variable in GWAS. The most promising candidate genes for CWT included SLIT2, PACRGL, KCNIP4, RP1, XKR4, LYN, RPS20, MOS, FAM110B, UBXN2B, CYP7A1, SDCBP, NSMAF, TOX, CA8, LAP3, FAM184B, and NCAPG. For EMA, the genes IBSP, LAP3, FAM184B, LCORL, NCAPG, SLC30A9, and BEND4 demonstrated significance. Similarly, CYP7B1, ARMC1, PDE7A, and CRH were associated with BF, while CTSZ, GNAS, VAPB, and RAB22A were associated with MS. This finding offers valuable insights into genomic regions and molecular mechanisms influencing Hanwoo carcass traits, aiding efficient breeding strategies.

Deacetylated Sialic Acid Sensitizes Lung and Colon Cancers to Novel Cucurbitacin-Inspired Estrone Epidermal Growth Factor Receptor (EGFR) Inhibitor Analogs

Cancers utilize sugar residues such as sialic acids (Sia) to improve their ability to survive. Sia presents a variety of functional group alterations, including O-acetylation on the C6 hydroxylated tail. Previously, sialylation has been reported to suppress EGFR activation and increase cancer cell sensitivity to Tyrosine Kinase Inhibitors (TKIs). In this study, we report on the effect of deacetylated Sia on the activity of three novel EGFR-targeting Cucurbitacin-inspired estrone analogs (CIEAs), MMA 294, MMA 321, and MMA 320, in lung and colon cancer cells. Acetylation was modulated by the removal of Sialate O-Acetyltransferase, also known as CAS1 Domain-containing protein (CASD1) gene via CRISPR-Cas9 gene editing. Using a variety of cell-based approaches including MTT cell viability assay, flow cytometry, immunofluorescence assay and in-cell ELISA we observed that deacetylated Sia-expressing knockout cells (1.24-6.49 μM) were highly sensitive to all CIEAs compared with the control cells (8.82-20.97 μM). Apoptosis and varied stage cell cycle arrest (G0/G1 and G2/M) were elucidated as mechanistic modes of action of the CIEAs. Further studies implicated overexpression of CIEAs' cognate protein target, phosphorylated EGFR, in the chemosensitivity of the deacetylated Sia-expressing knockout cells. This observation correlated with significantly decreased levels of key downstream proteins (phosphorylated ERK and mTOR) of the EGFR pathway in knockout cells compared with controls when treated with CIEAs. Collectively, our findings indicate that Sia deacetylation renders lung and colon cancer cells susceptible to EGFR therapeutics and provide insights for future therapeutic interventions.

Role of glycosylation in breast cancer progression and metastasis: implications for miRNA, EMT and multidrug resistance

Breast cancer (BC) is one of the leading causes of death in women, globally. A variety of biological processes results in metastasis, a poorly understood pathological phenomenon, causing a high relapse rate. Glycosylation, microribonucleic acids (miRNAs) and epithelial to mesenchymal transition (EMT), have been shown to regulate this cascade where tumor cells detach from their primary site, enter the circulatory system and colonize distant sites. Integrated proteomics and glycomics approaches have been developed to probe the molecular mechanism regulating such metastasis. In this review, we describe specific aspects of glycosylation and its interrelation with miRNAs, EMT and multidrug resistance during BC progression and metastasis. We explore various approaches that determine the role of proteomes and glycosylation in BC diagnosis, therapy and drug discovery.

Early in vitro evidence indicates that deacetylated sialic acids modulate multi-drug resistance in colon and lung cancers via breast cancer resistance protein

Cancers utilize sugar residues to engage in multidrug resistance. The underlying mechanism of action involving glycans, specifically the glycan sialic acid (Sia) and its various functional group alterations, has not been explored. ATP-binding cassette (ABC) transporter proteins, key proteins utilized by cancers to engage in multidrug resistant (MDR) pathways, contain Sias in their extracellular domains. The core structure of Sia can contain a variety of functional groups, including O-acetylation on the C6 tail. Modulating the expression of acetylated-Sias on Breast Cancer Resistance Protein (BCRP), a significant ABC transporter implicated in MDR, in lung and colon cancer cells directly impacted the ability of cancer cells to either retain or efflux chemotherapeutics. Via CRISPR-Cas-9 gene editing, acetylation was modulated by the removal of CAS1 Domain-containing protein (CASD1) and Sialate O-Acetyl esterase (SIAE) genes. Using western blot, immunofluorescence, gene expression, and drug sensitivity analysis, we confirmed that deacetylated Sias regulated a MDR pathway in colon and lung cancer in early in vitro models. When deacetylated Sias were expressed on BCRP, colon and lung cancer cells were able to export high levels of BCRP to the cell's surface, resulting in an increased BCRP efflux activity, reduced sensitivity to the anticancer drug Mitoxantrone, and high proliferation relative to control cells. These observations correlated with increased levels of cell survival proteins, BcL-2 and PARP1. Further studies also implicated the lysosomal pathway for the observed variation in BCRP levels among the cell variants. RNASeq data analysis of clinical samples revealed higher CASD1 expression as a favorable marker of survival in lung adenocarcinoma. Collectively, our findings indicate that deacetylated Sia is utilized by colon and lung cancers to engage in MDR via overexpression and efflux action of BCRP.

Cannabis Pharmacogenomics: A Path to Personalized Medicine

Cannabis and related compounds have created significant research interest as a promising therapy in many disorders. However, the individual therapeutic effects of cannabinoids and the incidence of side effects are still difficult to determine. Pharmacogenomics may provide the answers to many questions and concerns regarding the cannabis/cannabinoid treatment and help us to understand the variability in individual responses and associated risks. Pharmacogenomics research has made meaningful progress in identifying genetic variations that play a critical role in interpatient variability in response to cannabis. This review classifies the current knowledge of pharmacogenomics associated with medical marijuana and related compounds and can assist in improving the outcomes of cannabinoid therapy and to minimize the adverse effects of cannabis use. Specific examples of pharmacogenomics informing pharmacotherapy as a path to personalized medicine are discussed.

Prandial state and biological sex modulate clinically relevant efflux transporters to different extents in Wistar and Sprague Dawley rats

P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug resistance-associated protein 2 (MRP2) are clinically relevant efflux transporters implicated in the oral absorption of many food and drug substrates. Here, we hypothesised that food intake could influence protein and mRNA intestinal expression of P-gp/abcb1a, BCRP/abcg2, and MRP2/abcc2 differently in male and female Wistar and Sprague Dawley rats. To test this hypothesis, we used enzyme-linked immunosorbent assay (ELISA) and real-time polymerase chain reaction (PCR) to quantify the protein and mRNA intestinal expression of these transporters, respectively. Our study found food and sex differences in P-gp expression, whereby in the fed state P-gp expression decreased in male Wistar rats, but P-gp expression increased in females. In the fed state, BCRP expression increased in both male and female Wistar rats, compared with the fasted state. In contrast, no sex differences or food effect differences were seen in Sprague Dawley rats for P-gp and BCRP expression. On the other hand, in the fed state, MRP2 expression was higher in male and female Wistar and Sprague Dawley rats when compared with the fasted state. Sex differences were also observed in the fasted state. Overall, significant strain differences were reported for P-gp, BCRP and MRP2 expression. Strong to moderate positive linear correlations were found between ELISA and PCR quantification methods. ELISA may be more useful than PCR as it reports protein expression as opposed to transcript expression. Researchers must consider the influence of sex, strain and feeding status in preclinical studies of P-gp, BCRP and MRP2 drug substrates.

Design, synthesis, and biological evaluation of phenylurea indole derivatives as ABCG2 inhibitors

Three series of phenylurea indole derivatives were synthesized with potent inhibitory activities on ABCG2 with simple and efficient synthetic routes. Among these compounds, four phenylurea indole derivatives 3c-3f with extended π system were discovered as the most potent ABCG2 inhibitors, while these compounds showed no inhibition on ABCB1. Compounds 3c and 3f were selected for further investigation to explore the mechanisms of action on reversing ABCG2-mediated multidrug resistance (MDR). The results revealed that compounds 3c and 3f increased the accumulation of mitoxantrone (MX) in ABCG2-overexpressing cells, but they did not alter the expression level or localization of ABCG2 in cells. In addition, both 3c and 3f significantly stimulated the ATP hydrolysis of ABCG2 transporter indicating that they can be competitive substrates of ABCG2 transporter, and thereby increase the accumulation of mitoxantrone in ABCG2-overexpressing H460/MX20 cells. Both 3c and 3f was docked into the drug-binding site of the human ABCG2 transporter protein (PDB 6FFC) with high affinities. This study showed that extending the π system of phenylurea indole derivatives enhanced their inhibitory activities on ABCG2, which may provide a clue for the further research to discover more potent ABCG2 inhibitors.

Designing of new tetrahydro-β-carboline-based ABCG2 inhibitors using 3D-QSAR, molecular docking, and DFT tools

Human ATP-binding cassette superfamily G member 2 (ABCG2) protein is a member of the ABC transporter family, which is responsible for multidrug resistance (MDR) in cancerous cells. MDR reduces the effectiveness of chemotherapy in breast cancer, which is one of the leading causes of death in women globally. MDR in cancer cells is one of the immediate signs of progression of resistance; thus, various anticancer drugs can be designed. To reduce MDR, we utilized the tetrahydro-β-carboline (THβC) compound library. We accomplished a three-dimensional quantitative structure-activity relationship (3D-QSAR), scaffold hopping to design a new library of compounds of THβC, and further molecular docking, induced-fit docking (IFD), molecular mechanics energies combined with generalized born and surface area continuum solvation (MM-GBSA), drug-like features, ADMET properties, and density functional theory (DFT) studies were performed. From these studies, the best 3D-QSAR model (r2 = 0.99, q2 = 0.92) was found, and the necessity of electrostatic, steric, and hydrophobic field effects were determined that could modulate bioactivity. Moreover, based on electrostatic, steric, and hydrophobic field notations, new THβC derivatives (3409) were designed. These findings might provide new insight for researchers to perform in vitro and in vivo studies for better antagonists against MDR in treating breast cancer.Communicated by Ramaswamy H. Sarma.

Drug resistance of hepatoma cells induced by ATP‑binding cassette transporter G2 by reducing intracellular drug concentration

The side effects and drug resistance during chemotherapy seriously affect the outcome of and may lead to the failure of chemotherapy for patients with hepatoma. The aim of the present study was to investigate the association between the expression of ATP-binding cassette transporter G2 (ABCG2) in hepatoma cells and the drug resistance of hepatoma. An MTT assay was used to determine the half-maximal inhibitory concentration (IC₅₀) of Adriamycin (ADM) in hepatoma HepG2 cells after treatment with ADM for 24 h. An ADM-resistant hepatoma cell subline, HepG2/ADM, was generated from the HepG2 hepatoma cell line through a stepwise selection with ADM doses from 0.01 to 0.1 µg/ml. The HepG2/ABCG2 cell line, an ABCG2-overexpressing hepatoma cell line, was established by transfecting the ABCG2 gene into HepG2 cells. The MTT assay was then used to detect the IC₅₀ of ADM in HepG2/ADM and HepG2/ABCG2 cells after treatment with ADM for 24 h and the resistance index was calculated. The apoptosis, cell cycle and ABCG2 protein expression levels in HepG2/ADM, HepG2/ABCG2 cells, HepG2/PCDNA3.1 and their parental HepG2 cells were detected by flow cytometry. In addition, flow cytometry was used to detect the efflux effect of HepG2/ADM and HepG2/ABCG2 cells after ADM treatment. ABCG2 mRNA expression in cells was detected by reverse transcription-quantitative PCR. After 3 months of ADM treatment, HepG2/ADM cells grew stably in the cell culture medium containing 0.1 µg/ml ADM and the cells were named HepG2/ADM cells. ABCG2 was overexpressed in HepG2/ABCG2 cells. The IC₅₀ of ADM in HepG2, HepG2/PCDNA3.1, HepG2/ADM and HepG2/ABCG2 cells was 0.72±0.03, 0.74±0.01, 11.17±0.59 and 12.75±0.47 µg/ml, respectively. The cell apoptotic rate of HepG2/ADM and HepG2/ABCG2 cells was not significantly different compared with that of HepG2 and HepG2/PCDNA3.1 cells (P>0.05), but the G₀/G₁ phase population of the cell cycle decreased and the proliferation index increased significantly (P<0.05). The expression levels of ABCG2 gene and protein in HepG2/ADM and HepG2/ABCG2 cells were significantly higher than those in HepG2 and HepG2/PCDNA3.1 cells (P<0.01), but there was no significant difference between HepG2 and HepG2/PCDNA3.1 cells (P>0.05). The ADM efflux effect of HepG2/ADM and HepG2/ABCG2 cells was significantly higher than that of parental HepG2 and HepG2/PCDNA3.1 cells (P<0.05). Therefore, the present study demonstrated that ABCG2 expression is highly increased in drug-resistant hepatoma cells and that high expression of ABCG2 is involved in the drug resistance of hepatoma by reducing the intracellular drug concentration.

Design, Synthesis and Biological Evaluation of Quinazolinamine Derivatives as Breast Cancer Resistance Protein and P-Glycoprotein Inhibitors with Improved Metabolic Stability

A series of twenty-two quinazolinamine derivatives showing potent inhibitory activities on breast cancer resistance protein (BCRP) and p-glycoprotein (P-gp) were synthesized. A cyclopropyl-containing quinazolinamine 22 was identified as a dual BCRP and P-gp inhibitor, while azide-containing quinazolinamine 33 showed BCRP inhibitory activity. These lead compounds were further investigated in a battery of mechanistic experiments. Compound 22 changed the localization of BCRP and P-gp in cells, thus inhibiting the efflux of anticancer drugs by the two ATP-binding cassette (ABC) transporters. In addition, both 22 and 33 significantly stimulated the ATP hydrolysis of the BCRP transporter, indicating that they can be competitive substrates of the BCRP transporter, and thereby increase the accumulation of mitoxantrone in BCRP-overexpressing H460/MX20 cells. Azide derivative 33, exhibited a greater inhibitory effect on BCRP after UV activation and can serve as a valuable probe for investigating the interactions of quinazolinamine derivatives with BCRP. Notably, the dual BCRP and P-gp inhibitors 4-5, 22-24, 27, and BCRP inhibitor 33 showed improved metabolic stability compared to Ko143.

OAT, OATP, and MRP Drug Transporters and the Remote Sensing and Signaling Theory

The coordinated movement of organic anions (e.g., drugs, metabolites, signaling molecules, nutrients, antioxidants, gut microbiome products) between tissues and body fluids depends, in large part, on organic anion transporters (OATs) [solute carrier 22 (SLC22)], organic anion transporting polypeptides (OATPs) [solute carrier organic (SLCO)], and multidrug resistance proteins (MRPs) [ATP-binding cassette, subfamily C (ABCC)]. Depending on the range of substrates, transporters in these families can be considered multispecific, oligospecific, or (relatively) monospecific. Systems biology analyses of these transporters in the context of expression patterns reveal they are hubs in networks involved in interorgan and interorganismal communication. The remote sensing and signaling theory explains how the coordinated functions of drug transporters, drug-metabolizing enzymes, and regulatory proteins play a role in optimizing systemic and local levels of important endogenous small molecules. We focus on the role of OATs, OATPs, and MRPs in endogenous metabolism and how their substrates (e.g., bile acids, short chain fatty acids, urate, uremic toxins) mediate interorgan and interorganismal communication and help maintain and restore homeostasis in healthy and disease states.

Synthesis and Anticancer Evaluation of New Indole-Based Tyrphostin Derivatives and Their (p-Cymene)dichloridoruthenium(II) Complexes

New N-alkylindole-substituted 2-(pyrid-3-yl)-acrylonitriles with putative kinase inhibitory activity and their (p-cymene)Ru(II) piano-stool complexes were prepared and tested for their antiproliferative efficacy in various cancer models. Some of the indole-based derivatives inhibited tumor cell proliferation at (sub-)micromolar concentrations with IC₅₀ values below those of the clinically relevant multikinase inhibitors gefitinib and sorafenib, which served as positive controls. A focus was set on the investigation of drug mechanisms in HCT-116 p53-knockout colon cancer cells in order to evaluate the dependence of the test compounds on p53. Colony formation assays as well as experiments with tumor spheroids confirmed the excellent antineoplastic efficacy of the new derivatives. Their mode of action included an induction of apoptotic caspase-3/7 activity and ROS formation, as well as anti-angiogenic properties. Docking calculations with EGFR and VEGFR-2 identified the two 3-aryl-2-(pyrid-3-yl)acrylonitrile derivatives 2a and 2b as potential kinase inhibitors with a preferential activity against the VEGFR-2 tyrosine kinase. Forthcoming studies will further unveil the underlying mode of action of the promising new derivatives as well as their suitability as an urgently needed novel approach in cancer treatment.

Predicting disruptions to drug pharmacokinetics and the risk of adverse drug reactions in non-alcoholic steatohepatitis patients

The liver plays a central role in the pharmacokinetics of drugs through drug metabolizing enzymes and transporters. Non-alcoholic steatohepatitis (NASH) causes disease-specific alterations to the absorption, distribution, metabolism, and excretion (ADME) processes, including a decrease in protein expression of basolateral uptake transporters, an increase in efflux transporters, and modifications to enzyme activity. This can result in increased drug exposure and adverse drug reactions (ADRs). Our goal was to predict drugs that pose increased risks for ADRs in NASH patients. Bibliographic research identified 71 drugs with reported ADRs in patients with liver disease, mainly non-alcoholic fatty liver disease (NAFLD), 54 of which are known substrates of transporters and/or metabolizing enzymes. Since NASH is the progressive form of NAFLD but is most frequently undiagnosed, we identified other drugs at risk based on NASH-specific alterations to ADME processes. Here, we present another list of 71 drugs at risk of pharmacokinetic disruption in NASH, based on their transport and/or metabolism processes. It encompasses drugs from various pharmacological classes for which ADRs may occur when used in NASH patients, especially when eliminated through multiple pathways altered by the disease. Therefore, these results may inform clinicians regarding the selection of drugs for use in NASH patients.

A network pharmacological approach to reveal the multidrug resistance reversal and associated mechanisms of acetogenins against colorectal cancer

Multidrug Resistance (MDR) in tumors is caused by the over-expression of ATP Binding Cassette transporter proteins such as Multidrug Resistance Protein 1 and Breast Cancer Resistance Protein 1. This in silico study focuses on identifying a MDR inhibitor among acetogenins (AGEs) of Annona muricata and also aims at predicting colorectal cancer (CRC) core targets of AGEs through a network pharmacological approach. Twenty-four AGEs were initially screened for their ADME properties. Molecular interaction studies were performed with the two proteins MRP1 and BCRP1. As the structure of MRP1 was not available, an inward-facing conformation of MRP1 was modeled. A Protein-protein interaction network was constructed for the correlating targets of CRC. KEGG pathway and Gene Ontology analysis were performed for the predicted CRC targets. We identified four lead AGEs: Muricatocin B, Annonacinone, Annonacin A and Annomuricin E having a higher binding affinity towards MDR proteins. MD simulation studies performed with the three lead AGEs and the MDR proteins showed that MRP1(DBD): Annomuricin E complex was stable throughout the simulation. Our analysis revealed ABCG2, ERBB2, STAT3, AR, SRC and ABCC1 as CRC targets of the lead molecules. The top 10 signaling pathways and functions of correlative CRC targets were also predicted. We conclude that the identified lead molecules might act as competitive inhibitors for reversing MDR in CRC. Additionally, network pharmacological studies established the correlative CRC targets and their mechanisms of action. Further experimental studies are needed to validate our findings. Communicated by Ramaswamy H. Sarma.

Why Do Dietary Flavonoids Have a Promising Effect as Enhancers of Anthracyclines? Hydroxyl Substituents, Bioavailability and Biological Activity

Anthracyclines currently play a key role in the treatment of many cancers, but the limiting factor of their use is the widespread phenomenon of drug resistance and untargeted toxicity. Flavonoids have pleiotropic, beneficial effects on human health that, apart from antioxidant activity, are currently considered small molecules-starting structures for drug development and enhancers of conventional therapeutics. This paper is a review of the current and most important data on the participation of a selected series of flavonoids: chrysin, apigenin, kaempferol, quercetin and myricetin, which differ in the presence of an additional hydroxyl group, in the formation of a synergistic effect with anthracycline antibiotics. The review includes a characterization of the mechanism of action of flavonoids, as well as insight into the physicochemical parameters determining their bioavailability in vitro. The crosstalk between flavonoids and the molecular activity of anthracyclines discussed in the article covers the most important common areas of action, such as (1) disruption of DNA integrity (genotoxic effect), (2) modulation of antioxidant response pathways, and (3) inhibition of the activity of membrane proteins responsible for the active transport of drugs and xenobiotics. The increase in knowledge about the relationship between the molecular structure of flavonoids and their biological effect makes it possible to more effectively search for derivatives with a synergistic effect with anthracyclines and to develop better therapeutic strategies in the treatment of cancer.

The Tetrahydroisoquinoline Scaffold in ABC Transporter Inhibitors that Act as Multidrug Resistance (MDR) Reversers

BACKGROUND

The failure of anticancer chemotherapy is often due to the development of resistance to a variety of anticancer drugs. This phenomenon is called multidrug resistance (MDR) and is related to the overexpression of ABC transporters, such as P-glycoprotein, multidrug resistance- associated protein 1 and breast cancer resistance protein. Over the past few decades, several ABC protein modulators have been discovered and studied as a possible approach to evade MDR and increase the success of anticancer chemotherapy. Nevertheless, the co-administration of pump inhibitors with cytotoxic drugs, which are substrates of the transporters, does not appear to be associated with an improvement in the therapeutic efficacy of antitumor agents. However, more recently discovered MDR reversing agents, such as the two tetrahydroisoquinoline derivatives tariquidar and elacridar, are characterized by high affinity towards the ABC proteins and by reduced negative properties. Consequently, many analogs of these two derivatives have been synthesized, with the aim of optimizing their MDR reversal properties.

OBJECTIVE

This review aims to describe the MDR modulators carrying the tetraidroisoquinoline scaffold reported in the literature in the period 2009-2021, highlighting the structural characteristics that confer potency and/or selectivity towards the three ABC transport proteins.

RESULTS AND CONCLUSION

Many compounds have been synthesized in the last twelve years showing interesting properties, both in terms of potency and selectivity. Although clear structure-activity relationships can be drawn only by considering strictly related compounds, some of the compounds reviewed could be promising starting points for the design of new ABC protein inhibitors.

Are active efflux transporters contributing to infant drug exposure via breastmilk? A longitudinal study

Although most drugs are considered safe and compatible with breastfeeding, cases of toxic drug exposure have been reported. Active efflux transporters have been implicated as a mechanism in the transfer of drugs from mother to baby via breastmilk. Using breastmilk as a source of human mammary epithelial cells, this novel longitudinal study investigated the expression of four active transporters, namely, MDR1, MRP1, MRP2 and BCRP in the lactating human breast. BCRP gene was found to be strongly overexpressed with levels peaking at 5 months postpartum, potentially indicating a time where a breastfed infant may be at risk of inadvertent exposure to BCRP substrates. Serum albumin, a major component of human breastmilk was increasingly downregulated as lactation progresses. Xanthine oxidase/dehydrogenase, an enzyme in breastmilk attributed to a reduced risk of gastroenteritis caused by Escherichia coli and Salmonella enteritides, was downregulated. Lysozyme and fatty acid synthase are progressively upregulated. This study also shows that breastmilk-derived epithelial cells, when propagated in culture, exhibit characteristics significantly different to those derived directly from breastmilk. This serves to warn that in vitro studies are not a true representation of in vivo processes in the lactating breast; hence, application of in vitro data should be conducted with caution.

Applications of Nanotechnology-based Approaches to Overcome Multi-drug Resistance in Cancer

Cancer is one of the leading causes of death worldwide. Chemotherapy and radiation therapy are the major treatments used for the management of cancer. Multidrug resistance (MDR) is a major hindrance faced in the treatment of cancer and is also responsible for cancer relapse. To date, several studies have been carried out on strategies to overcome or reverse MDR in cancer. Unfortunately, the MDR reversing agents have been proven to have minimal clinical benefits, and eventually, no improvement has been made in therapeutic efficacy to date. Thus, several investigational studies have also focused on overcoming drug resistance rather than reversing the MDR. In this review, we focus primarily on nanoformulations regarded as a novel approach to overcome or bypass the MDR in cancer. The nanoformulation systems serve as an attractive strategy as these nanosized materials selectively get accumulated in tumor tissues, thereby improving the clinical outcomes of patients suffering from MDR cancer. In the current work, we present an overview of recent trends in the application of various nano-formulations, belonging to different mechanistic classes and functionalization like carbon nanotubes, carbon nanohorns, carbon nanospheres, liposomes, dendrimers, etc., to overcome MDR in cancer. A detailed overview of these techniques will help researchers in exploring the applicability of nanotechnologybased approaches to treat MDR.

PFKFB3 regulates cancer stemness through the hippo pathway in small cell lung carcinoma

PFKFB3 (6-phosphofructo-2-kinase) is the rate-limiting enzyme of glycolysis and is overexpressed in several human cancers that are associated with poor prognosis. High PFKFB3 expression in cancer stem cells promotes glycolysis and survival in the tumor microenvironment. Inhibition of PFKFB3 by the glycolytic inhibitor PFK158 and by shRNA stable knockdown in small cell lung carcinoma (SCLC) cell lines inhibited glycolysis, proliferation, spheroid formation, and the expression of cancer stem cell markers CD133, Aldh1, CD44, Sox2, and ABCG2. These factors are also associated with chemotherapy resistance. We found that PFK158 treatment and PFKFB3 knockdown enhanced the ABCG2-interacting drugs doxorubicin, etoposide, and 5-fluorouracil in reducing cell viability under conditions of enriched cancer stem cells (CSC). Additionally, PFKFB3 inhibition attenuated the invasion/migration of SCLC cells by downregulating YAP/TAZ signaling while increasing pLATS1 via activation of pMST1 and NF2 and by reducing the mesenchymal protein expression. PFKFB3 knockdown and PFK158 treatment in a H1048 SCLC cancer stem cell-enriched mouse xenograft model showed significant reduction in tumor growth and weight with reduced expression of cancer stem cell markers, ABCG2, and YAP/TAZ. Our findings identify that PFKFB3 is a novel target to regulate cancer stem cells and its associated therapeutic resistance markers YAP/TAZ and ABCG2 in SCLC models.

Association of ABCG2 polymorphisms with susceptibility to anti-tuberculosis drug-induced hepatotoxicity in the Chinese population

Background The accumulation of endogenous hepatotoxin protoporphyrin IX (PPIX) in the liver was proposed to be a novel mechanism of anti-tuberculosis drug-induced hepatotoxicity (ATDH). ATP-binding cassette transporter G2 (ABCG2) plays an important role in modulating PPIX concentrations. This study aimed to explore the role of ABCG2 genetic polymorphisms in the risk of ATDH in Chinese patients.Methods A 1:4 matched case-control study was performed among 202 ATDH cases and 808 controls. Conditional logistic regression model was used to estimate the association between genotypes and the risk of ATDH by odds ratios (ORs) with 95% confidence intervals (CIs).Results Male patients with CC genotype of rs2622605 had an increased risk of ATDH (adjusted OR =1.615, 95% CI: 1.119-2.332, P = 0.011). The peak value of alkaline phosphatase was significantly higher in male patients with CC genotype of rs2622605 than in those with TT + TC genotype during antituberculosis treatment (102.0 U/L vs. 98.0 U/L, P = 0.029).Conclusions This is the first attempt to evaluate the association between ABCG2 genetic variants and the risk of ATDH. Based on the 1:4 matched case-control study, the polymorphism at rs2622605 in the ABCG2 gene may be associated with the susceptibility to ATDH in Chinese male patients.

An association study of ABCG2 rs2231142 on the concentrations of allopurinol and its metabolites

ABCG2 is a gene that codes for the human breast cancer resistance protein (BCRP). It is established that rs2231142 G>T, a single nucleotide polymorphism of the ABCG2 gene, is associated with gout and poor response to allopurinol, a uric acid‐lowering agent used to treat this condition. It has also been suggested that oxypurinol, the primary active metabolite of allopurinol, is a substrate of the BCRP. We thus hypothesized that carrying the rs2231142 variant would be associated with decreased oxypurinol concentrations, which would explain the lower reduction in uric acid. We performed a cross‐sectional study to investigate the association between the ABCG2 rs2231142 variant and oxypurinol, allopurinol, and allopurinol riboside concentrations in 459 participants from the Montreal Heart Institute Hospital Cohort. Age, sex, weight, use of diuretics, and estimated glomerular filtration rate were all significantly associated with oxypurinol plasma concentration. No association was found between rs2231142 and oxypurinol, allopurinol and allopurinol riboside plasma concentrations. Rs2231142 was not significantly associated with daily allopurinol dose in the overall population, but an association was observed in men, with T carriers receiving higher doses. Our results do not support a major role of ABCG2 in the pharmacokinetics of allopurinol or its metabolites. The underlying mechanism of the association between rs2231142 and allopurinol efficacy requires further investigation.

Multidrug Resistance in Cancer Cells: Focus on a Possible Strategy Plan to Address Colon Carcinoma Cells

Even though various treatment methods are available for cancer, the death curve is not reducing. The diagnosis of cancer at the fourth stage and drug resistance are the leading reasons for treatment failure and lower survival rates. In this review article, we summarize the possible pitfalls during cancer treatment in general, which mainly include multidrug resistance, and propose a hypothesis for colorectal cancer specifically. We also evaluate multidrug resistance in cancer in general and colorectal cancer in particular and hypothesize a concept based on combination therapy with 5-fluorouracil, curcumin, and lipids for the possible management of colorectal cancer. In addition, a hypothetical approach, combining a synthetic agent and a natural chemotherapeutic agent, to treating colorectal cancer is also discussed. This hypothesis could improve the management of colorectal cancer.

Systemic Mobilization of Breast Cancer Resistance Protein in Response to Oncogenic Stress

Simple Summary

The drug efflux mediated by xenobiotic transporters is one of the best recognized mechanisms of multidrug resistance in cancer that leads to the failure of therapeutic approaches. The aim of our research was to examine the influence of a growing tumor on the activity of xenobiotic transport in the host. Our study reveals a strong correlation between the development of melanoma tumor in mice and the level of breast cancer resistance protein, one of the major xenobiotic transporters, and its transcript in the normal tissues of the hosts distant from the tumor site. The systemic effects of the tumor are confirmed by a drastically enhanced xenobiotic transport, which is correlated with changes in the level of cytokines in blood. Such an unexpected type of tumor–host interaction, which leads to the systemic upregulation of breast cancer resistance protein, and very likely of other xenobiotic transporters too, has broad implications for cancer therapies, including chemotherapy and photodynamic therapy. Our findings shed new light on the biology of cancer and the complexity of cancer–host interactions that should be taken into account in the design of new generations of anti-cancer drugs and personalized medicine.

Abstract

The breast cancer resistance protein (BCRP or ABCG2) involved in cancer multidrug resistance (MDR), transports many hydrophobic compounds, including a number of anti-cancer drugs. Our comprehensive study using a mouse model reveals that a subcutaneously growing tumor strongly affects the expression of BCRP in the host’s normal organs on both the transcriptional and translational level. Additionally, the efflux of BCRP substrates is markedly enhanced. The levels of BCRP and its transcript in normal tissues distant from the tumor site correlate with tumor growth and the levels of cytokines in the peripheral blood. Thus, oncogenic stress causes transient systemic upregulation of BCRP in the host’s normal tissues and organs, which is possibly mediated via cytokines. Because BCRP upregulation takes place in many organs as early as the initial stages of tumor development, it reveals a most basic mechanism that may be responsible for the induction of primary MDR. We hypothesize that such effects are not tumor-specific responses, but rather constitute a more universal defense strategy. The xenobiotic transporters are systemically mobilized due to various stresses, seemingly in a pre-emptive manner so that the body can be quickly and efficiently detoxified. Our findings shed new light on the biology of cancer and on the complexity of cancer–host interactions and are highly relevant to cancer therapies as well as to the design of new generations of therapeutics and personalized medicine.

Therapeutic spectrum of piperine for clinical practice: a scoping review

Translation of traditional knowledge of herbs into a viable product for clinical use is still an uphill task. Piperine, a pungent alkaloid molecule derived from Piper nigrum and Piper longum possesses diverse pharmacological effects. Traditionally, pepper is used for arthritis, bronchitis, gastritis, diarrhea, snake bite, menstrual pain, fever, and bacterial infections, etc. The anti-inflammatory, antioxidant and immunomodulatory actions of piperine are the possible mechanisms behind its therapeutic potential. Various in-silico and experimental studies have shown piperine as a possible promising molecule in coronavirus disease (COVID-19), ebola, and dengue due to its immunomodulatory and antiviral activities. The other important clinical applications of piperine are due to its bio enhancing effect on drugs, by modulating, absorption in the gastrointestinal tract, altering activities of transporters like p-glycoprotein substrates, and modulating drug metabolism by altering the expression of cytochrome P450 or UDP-glucuronosyltransferase enzymes. Piperine attracted clinicians in treating patients with arthritis, metabolic syndrome, diabetes, skin infections, gastric and liver disorders. This review focused on systematic, evidence-based insight into the use of piperine in clinical settings and mechanistic details behind its therapeutic actions. Also, highlights a number of clinical trials of piperine at various stages exploring its clinical application in cancer, neurological, respiratory, and viral disease, etc.

Magnolol and Honokiol Inhibited the Function and Expression of BCRP with Mechanism Exploration

Breast cancer resistance protein (BCRP), one of the ATP-binding cassette (ABC) transporters, was associated with the multidrug resistance (MDR) of chemotherapy. Magnolol (MN) and honokiol (HK) are major bioactive polyphenols of Magnolia officinalis. This study investigated the effects of MN and HK on the function and expression of BCRP for the purpose of developing BCRP inhibitor to overcome MDR. Cell lines including MDCKII-BCRP and MDCKII-WT were used for evaluating the function and expression of BCRP. The results showed that MN (100-12.5 µM) and HK (100-12.5 µM) significantly decreased the function of BCRP by 80~12% and 67~14%, respectively. In addition, MN and HK were verified as substrates of BCRP. Furthermore, MN and HK reduced the protein expression of BCRP, and inhibited the phosphorylation of epidermal growth factor receptor (EGFR) and phosphatidylinositol 3-kinase (PI3K). In conclusion, both MN and HK decreased the function and expression of BCRP via EGFR/PI3K signaling pathway. Therefore, both compounds were promising candidates for reversing the MDR of chemotherapy.

A Phenylfurocoumarin Derivative Reverses ABCG2-Mediated Multidrug Resistance In Vitro and In Vivo

The ATP-binding cassette subfamily G member 2 (ABCG2) transporter is involved in the development of multidrug resistance in cancer patients. Many inhibitors of ABCG2 have been reported to enhance the chemosensitivity of cancer cells. However, none of these inhibitors are being used clinically. The aim of this study was to identify novel ABCG2 inhibitors by high-throughput screening of a chemical library. Among the 5812 compounds in the library, 23 compounds were selected in the first screening, using a fluorescent plate reader-based pheophorbide a (PhA) efflux assay. Thereafter, to validate these compounds, a flow cytometry-based PhA efflux assay was performed and 16 compounds were identified as potential inhibitors. A cytotoxic assay was then performed to assess the effect these 16 compounds had on ABCG2-mediated chemosensitivity. We found that the phenylfurocoumarin derivative (R)-9-(3,4-dimethoxyphenyl)-4-((3,3-dimethyloxiran-2-yl)methoxy)-7H-furo [3,2-g]chromen-7-one (PFC) significantly decreased the IC₅₀ of SN-38 in HCT-116/BCRP colon cancer cells. In addition, PFC stimulated ABCG2-mediated ATP hydrolysis, suggesting that this compound interacts with the substrate-binding site of ABCG2. Furthermore, PFC reversed the resistance to irinotecan without causing toxicity in the ABCG2-overexpressing HCT-116/BCRP cell xenograft mouse model. In conclusion, PFC is a novel inhibitor of ABCG2 and has promise as a therapeutic to overcome ABCG2-mediated MDR, to improve the efficiency of cancer chemotherapy.

Glycyrrhizin as a Nitric Oxide Regulator in Cancer Chemotherapy

Simple Summary

Glycyrrhizin (GL) has anti-cancer, anti-inflammatory, anti-viral, and anti-oxidant activity. In particular, GL reduces multidrug resistance (MDR) in cancer cells, which is a major obstacle to chemotherapy. Nitric oxide (NO) also plays an important role in MDR, and GL affects NO concentration in the tumor microenvironment. However, the effects of GL and NO interaction on MDR have not been reviewed. Here, we review the role of GL as an NO regulator in cancer cells and its subsequent anti-MDR effect and posit that GL is a promising MDR inhibitor for cancer chemotherapy.

Abstract

Chemotherapy is used widely for cancer treatment; however, the evolution of multidrug resistance (MDR) in many patients limits the therapeutic benefits of chemotherapy. It is important to overcome MDR for enhanced chemotherapy. ATP-dependent efflux of drugs out of cells is the main mechanism of MDR. Recent studies have suggested that nitric oxide (NO) can be used to overcome MDR by inhibiting the ATPase function of ATP-dependent pumps. Several attempts have been made to deliver NO to the tumor microenvironment (TME), however there are limitations in delivery. Glycyrrhizin (GL), an active compound of licorice, has been reported to both reduce the MDR effect by inhibiting ATP-dependent pumps and function as a regulator of NO production in the TME. In this review, we describe the potential role of GL as an NO regulator and MDR inhibitor that efficiently reduces the MDR effect in cancer chemotherapy.