Designed P-glycoprotein inhibitors with triazol-tetrahydroisoquinoline-core increase doxorubicin-induced mortality in multidrug resistant K562/A02 cells

Recent developments of P-glycoprotein inhibitors and its structure-activity relationship (SAR) studies

P-glycoprotein (P-gp) over-expression is a key factor in multi-drug resistance (MDR), which is a major factor in the failure of cancer treatment. P-gp inhibitors have been demonstrated to have powerful pharmacological properties and may be used as a therapeutic approach to overcome the MDR in cancer cells. Combining clinical investigations with biochemical and computational research may potentially lead to a clearer understanding of the pharmacological properties and the mechanisms of action of these P-gp inhibitors. The task of turning these discoveries into effective therapeutic candidates for a variety of malignancies, including resistant and metastatic kinds, falls on medicinal chemists. A variety of P-gp inhibitors with great potency, high selectivity, and minimal toxicity have been identified in recent years. The latest advances in drug design, characterization, structure-activity relationship (SAR) research, and modes of action of newly synthesized, powerful small molecules P-gp inhibitors over the previous ten years are highlighted in this review. P-gp transporter over-expression has been linked to MDR, therefore the development of P-gp inhibitors will expand our understanding of the processes and functions of P-gp-mediated drug efflux, which will be helpful for drug discovery and clinical cancer therapies.

Design, Synthesis, and Biological Evaluation of Marine Lissodendrins B Analogues as Modulators of ABCB1-Mediated Multidrug Resistance

Multidrug resistance (MDR) caused by ATP-Binding Cassette Subfamily B Member 1 (ABCB1, P-glycoprotein, P-gp) is a major barrier for the success of chemotherapy in clinics. In this study, we designed and synthesized a total of 19 Lissodendrins B analogues and tested their ABCB1-mediated MDR reversal activity in doxorubicin (DOX)-resistant K562/ADR and MCF-7/ADR cells. Among all derivatives, compounds D₁, D₂, and D₄ with a dimethoxy-substituted tetrahydroisoquinoline fragment possessed potent synergistic effects with DOX and reversed ABCB1-mediated drug resistance. Notably, the most potent compound D₁ merits multiple activities, including low cytotoxicity, the strongest synergistic effect, and effectively reversing ABCB1-mediated drug resistance of K562/ADR (RF = 1845.76) and MCF-7/ADR cells (RF = 207.86) to DOX. As a reference substance, compound D₁ allows for additional mechanistic studies on ABCB1 inhibition. The synergistic mechanisms were mainly related to the increased intracellular accumulation of DOX via inhibiting the efflux function of ABCB1 rather than from affecting the expression level of ABCB1. These studies suggest that compound D₁ and its derivatives might be potential MDR reversal agents acting as ABCB1 inhibitors in clinical therapeutics and provide insight into a design strategy for the development of ABCB1 inhibitors.

A multi-functional nano-system combining PI3K-110α/β inhibitor overcomes P-glycoprotein mediated MDR and improves anti-cancer efficiency

P-glycoprotein (P-gp/ABCB1)-mediated multidrug resistance (MDR) in cancers severely limit chemotherapeutic efficacy. We recently reported that phosphatidylinositol-3-kinase (PI3K) 110α and 110β subunits can be novel targets for reversal of P-gp mediated MDR in cancers, and BAY-1082439 as an inhibitor specific for PI3K 110α and 110β subunits could reverse P-gp-mediated MDR by downregulating P-gp expression in cancer cells. However, BAY-1082439 has very low solubility, short half-life and high in-vivo clearance rate. Till now, nano-system with the functions to target PI3K P110α and P110β and reverse P-gp mediated MDR in cancers has not been reported. In our study, a tumor targeting drug delivery nano-system PBDF was established, which comprised doxorubicin (DOX) and BAY-1082439 respectively encapsulated by biodegradable PLGA-SH nanoparticles (NPs) that were grafted to gold nanorods (Au NRs) modified with FA-PEG-SH, to enhance the efficacy to reverse P-gp mediated MDR and to target tumor cells, further, to enhance the efficiency to inhibit MDR tumors overexpressing P-gp. In-vitro experiments indicated that PBDF NPs greatly enhanced uptake of DOX, improved the activity to reverse MDR, inhibited the cell proliferation, and induced S-phase arrest and apoptosis in KB-C2 cells, as compared with free DOX combining free BAY-1082439. In-vivo experiments further demonstrated that PBDF NPs improved the anti-tumor ability of DOX and inhibited development of KB-C2 tumors. Notably, the metastasis of KB-C2 cells in livers and lungs of nude mice were inhibited by treatment with PBDF NPs, which showed no obvious in-vitro or in-vivo toxicity.

Design and evaluation of dibenzoazepine-tetrahydroisoquinoline hybrids as potential P-glycoprotein inhibitors against multidrug resistant K562/A02 cells

Multidrug resistance (MDR) caused by P-glycoprotein (P-gp) is a main barrier to the success of cancer chemotherapies. In this study, fourteen novel dibenzoazepine-tetrahydroisoquinoline hybrids were prepared as potential P-gp inhibitors to surmount MDR caused by P-gp. Amongst them, 8a displayed the most potent inhibition effect on P-gp, thus effectively reversing P-gp-mediated drug resistance with a reversal fold (RF) value of 93.17 in K562/A02 cells. Excitingly, the EC₅₀ value of 8a on MDR reversing effect was 48.74 nM, which was nearly two thousand-fold lower than its IC₅₀ value (95.94 μM) for intrinsic cytotoxicity on K562/A02 cells. Further investigation showed that 8a exerted the MDR reversal effect through impairing P-gp function rather than affecting its expression. Molecular docking and CETSA results illustrated that 8a possessed a relatively high affinity for P-gp, thus effectively improving the stability of P-gp. Furthermore, 8a exhibited a much poorer inhibitory effect on CYP3A4 activity than CYP3A4 inhibitor ketoconazole, thus might not cause unfavorable drug-drug interactions. These data together suggested that 8a may be a promising lead to design P-gp inhibitors, and warranted further investigation on overcoming P-gp-mediated MDR.

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.

Overcoming multidrug resistance through targeting ABC transporters: lessons for drug discovery

INTRODUCTION

The argument around cancer therapy is an old one. Using chemotherapeutic drugs, as one of the most effective strategies in treatment of malignancies, is restricted by various issues that progress during therapy and avoid achieving clinical endpoints. Multidrug resistance (MDR), frequently mediated by ATP-binding cassette (ABC) transporters, is one of the most recognized obstacles in the success of pharmacological anticancer approaches. These transporters efflux diverse drugs to extracellular environment, causing MDR and responsiveness of tumor cells to chemotherapy diminishes.

AREAS COVERED

Several strategies have been used to overcome MDR phenomenon. Succession in this field requires complete knowledge about features and mechanism of ABC transporters. In this review, conventional synthetic and natural inhibitors are discussed first and then novel approaches including RNA, monoclonal antibodies, nanobiotechnology, and structural modification techniques are represented.

EXPERT OPINION

With increasing frequency of MDR in cancer cells, it is essential to develop new drugs to inhibit MDR. Using knowledge acquired about ABC transporter's structure, rational design of inhibitors is possible. Also, some herbal products have shown to be potential lead compounds in drug discovery for reversal of MDR.

Therapeutic potential of 1,2,3-triazole hybrids for leukemia treatment

Leukemia, a hematological malignancy originating from the bone marrow, is the principal cancer of childhood. In recent decades, improved remission rates and survival of patients with leukemia have been achieved due to significant breakthroughs in the treatment. However, chemoresistance and relapse are common, creating an urgent need for the search for novel pharmaceutical interventions. 1,2,3-Triazole is one of the most fascinating pharmacophores in the discovery of new drugs, and several 1,2,3-triazole derivatives have already been used in clinics or are under clinical evaluation for the treatment of cancers. In particular, 1,2,3-triazole hybrids could suppress tumor proliferation, invasion, and metastasis by inhibiting enzymes, proteins, and receptors in cancer cells, revealing their potential as putative antileukemic agents. This review covers the recent advances regarding the 1,2,3-triazole hybrids with potential antileukemic activity, focusing on the chemical structures, structure-activity relationship, and mechanisms of action, covering articles published from January 2017 to January 2022.

Advances in understanding the role of P-gp in doxorubicin resistance: Molecular pathways, therapeutic strategies, and prospects

P-glycoprotein (P-gp) is a drug efflux transporter that triggers doxorubicin (DOX) resistance. In this review, we highlight the molecular avenues regulating P-gp, such as Nrf2, HIF-1α, miRNAs, and long noncoding (lnc)RNAs, to reveal their participation in DOX resistance. These antitumor compounds and genetic tools synergistically reduce P-gp expression. Furthermore, ATP depletion impairs P-gp activity to enhance the antitumor activity of DOX. Nanoarchitectures, including liposomes, micelles, polymeric nanoparticles (NPs), and solid lipid nanocarriers, have been developed for the co-delivery of DOX with anticancer compounds and genes enhancing DOX cytotoxicity. Surface modification of nanocarriers, for instance with hyaluronic acid (HA), can promote selectivity toward cancer cells. We discuss these aspects with a focus on P-gp expression and activity.

Structure activity relationships and the binding mode of quinolinone-pyrimidine hybrids as reversal agents of multidrug resistance mediated by P-gp

P-gp-associated multidrug resistance is a major impediment to the success of chemotherapy. With the aim of finding non-toxic and effective P-gp inhibitors, we investigated a panel of quinolin-2-one-pyrimidine hybrids. Among the active compounds, two of them significantly increased intracellular doxorubicin and rhodamine 123 accumulation by inhibiting the efflux mediated by P-gp and restored doxorubicin toxicity at nanomolar range. Structure-activity relationships showed that the number of methoxy groups, an optimal length of the molecule in its extended conformation, and at least one flexible methylene group bridging the quinolinone to the moiety bearing the pyrimidine favored the inhibitory potency of P-gp. The best compounds showed a similar binding pattern and interactions to those of doxorubicin and tariquidar, as revealed by MD and hybrid QM/MM simulations performed with the recent experimental structure of P-gp co-crystallized with paclitaxel. Analysis of the molecular interactions stabilizing the different molecular complexes determined by MD and QTAIM showed that binding to key residues from TMH 4-7 and 12 is required for inhibition.

1,2,3,4-Tetrahydroisoquinoline (THIQ) as privileged scaffold for anticancer de novo drug design

Introduction: Cancer is a dreadful disorder that is emerging as one of the leading causes of mortality across the globe. The complex tumor environment, supplemented with drawbacks of the existing drugs, has made it a global health concern. The Tetrahydroisoquinoline (THIQ) ring holds an important position in medicinal chemistry due to its wide range of pharmacological properties. Several THIQ based natural products have been previously explored for their antitumor properties, making it a vital scaffold for anticancer drug design.Areas covered: This review article addresses the potential of THIQ as anticancer agents. Various medicinal chemistry strategies employed for the design and development of THIQ analogs as inhibitors or modulators of relevant anticancer targets have been discussed in detail. Moreover, the common strategies employed for the synthesis of the core scaffold are also highlighted.Expert opinion: Evidently, THIQs have tremendous potential in anticancer drug design. Some of these analogs exhibited potent activity against various cancer molecular targets. However, there are some drawbacks, such as selectivity that need addressing. The synthetic ease for constructing the core scaffold complimented with its reactivity makes it ideal for further structure-activity relationship studies. For these reasons, THIQ is a privileged scaffold for the design and development of novel anticancer agents.

Assessment of Thiosemicarbazone-Containing Compounds as Potential Antileukemia Agents against P-gp Overexpressing Drug Resistant K562/A02 Cells

P-Glycoprotein (P-gp) overexpression is considered to be the leading cause of multidrug resistance (MDR) and failure of chemotherapy for leukemia. In this study, seventeen thiosemicarbazone-containing compounds were prepared and evaluated as potential antileukemia agents against drug resistant K562/A02 cell overexpressing P-gp. Among them, N-hydroxy-6-({(2E)-2-[(3-nitrophenyl)methylidene]hydrazinecarbothioyl}amino)hexanamide could significantly inhibit K562/A02 cells proliferation with an IC₅₀ value of 0.96 μM. Interestingly, N-hydroxy-6-({(2E)-2-[(3-nitrophenyl)methylidene]hydrazinecarbothioyl}amino)hexanamide could dose-dependently increase ROS levels of drug resistant K562/A02 cells, thus displaying a potential collateral sensitivity (CS)-inducing effect and selectively killing K562/A02 cells. Furthermore, N-hydroxy-6-({(2E)-2-[(3-nitrophenyl)methylidene]hydrazinecarbothioyl}amino)hexanamide possessed potent inhibitory effect on HDAC1 and HDAC6, and could promote K562/A02 cells apoptosis via dose-dependently increasing Bax expression, reducing Bcl-2 protein level, and inducing the cleavage of PARP and caspase3. These present findings suggest that N-hydroxy-6-({(2E)-2-[(3-nitrophenyl)methylidene]hydrazinecarbothioyl}amino)hexanamide might be a promising lead to discover novel antileukemia agents against P-gp overexpressing leukemic cells.

Design, Synthesis and Biological Evaluation of Dimethyl Cardamonin (DMC) Derivatives as P-glycoprotein-mediated Multidrug Resistance Reversal Agents

Background:

P-glycoprotein (P-gp) has been regarded as an important factor in the multidrug resistance (MDR) of tumor cells within the last decade, which can be solved by inhibiting Pgp to reverse MDR. Thus, it is an effective strategy to develop inhibitor of P-gp.

Objective:

In this study, the synthesis of a series of derivatives had been carried out by bioisosterism design on the basis of Dimethyl Cardamonin (DMC). Subsequently, we evaluated their reversal activities as potential P-glycoprotein (P-gp)-mediated Multidrug Resistance (MDR) agents.

Methods:

Dimethyl cardamonin derivatives were synthesized from acetophenones and the corresponding benzaldehydes in the presence of 40% KOH by Claisen-Schmidt reaction. Their cytotoxicity and reversal activities in vitro were assessed with MTT. Moreover, the compound B4 was evaluated by Doxorubicin (DOX) accumulation, Western blot and wound-healing assays deeply.

Results and Conclusion:

The results showed that compounds B2, B4 and B6 had the potency of MDR reversers with little intrinsic cytotoxicity. Meanwhile, these compounds also demonstrated the capability to inhibit MCF-7 and MCF-7/DOX cells migration. Besides, the most compound B4 was selected for further study, which promoted the accumulation of DOX in MCF-7/DOX cells and inhibited the expressionof P-gp at protein levels.

Conclusion:

The above findings may provide new insights for the research and development of Pgp- mediated MDR reversal agents.

Chemical molecular-based approach to overcome multidrug resistance in cancer by targeting P-glycoprotein (P-gp)

Multidrug resistance (MDR) remains one of the major impediments for efficacious cancer chemotherapy. Increased efflux of multiple chemotherapeutic drugs by transmembrane ATP-binding cassette (ABC) transporter superfamily is considered one of the primary causes for cancer MDR, in which the role of P-glycoprotein (P-gp/ABCB1) has been most well-established. The clinical co-administration of P-gp drug efflux inhibitors, in combination with anticancer drugs which are P-gp transport substrates, was considered to be a treatment modality to surmount MDR in anticancer therapy by blocking P-gp-mediated multidrug efflux. Extensive attempts have been carried out to screen for sets of nontoxic, selective, and efficacious P-gp efflux inhibitors. In this review, we highlight the recent achievements in drug design, characterization, structure-activity relationship (SAR) studies, and mechanisms of action of the newly synthetic, potent small molecules P-gp inhibitors in the past 5 years. The development of P-gp inhibitors will increase our knowledge of the mechanisms and functions of P-gp-mediated drug efflux which will benefit drug discovery and clinical cancer therapeutics where P-gp transporter overexpression has been implicated in MDR.

Current scenario of indole derivatives with potential anti-drug-resistant cancer activity

Cancer chemotherapy is frequently hampered by drug resistance, so the resistance to anticancer agents represents one of the major obstacles for the effective cancer treatment. Indole derivatives have the potential to act on diverse targets in cancer cells and exhibit promising activity against drug-resistant cancers. Moreover, some indole-containing compounds such as Semaxanib, Sunitinib, Vinorelbine, and Vinblastine have already been applied in clinics for various kinds of cancer even drug-resistant cancer therapy. Thus, indole derivatives are one of significant resources for the development of novel anti-drug-resistant cancer agents. This review focuses on the recent development of indole derivatives with potential therapeutic application for drug-resistant cancers, and the mechanisms of action, the critical aspects of design as well as structure-activity relationships, covering articles published from 2010 to 2020.

Medicinal chemistry strategies to discover P-glycoprotein inhibitors: An update

The presence of multidrug resistance (MDR) in malignant tumors is one of the primary causes of treatment failure in cancer chemotherapy. The overexpression of the ATP binding cassette (ABC) transporter, P-glycoprotein (P-gp), which significantly increases the efflux of certain anticancer drugs from tumor cells, produces MDR. Therefore, inhibition of P-gp may represent a viable therapeutic strategy to overcome cancer MDR. Over the past 4 decades, many compounds with P-gp inhibitory efficacy (referred to as first- and second-generation P-gp inhibitors) have been identified or synthesized. However, these compounds were not successful in clinical trials due to a lack of efficacy and/or untoward toxicity. Subsequently, third- and fourth-generation P-gp inhibitors were developed but dedicated clinical trials did not indicate a significant therapeutic effect. In recent years, an extraordinary array of highly potent, selective, and low-toxicity P-gp inhibitors have been reported. Herein, we provide a comprehensive review of the synthetic and natural products that have specific inhibitory activity on P-gp drug efflux as well as promising chemosensitizing efficacy in MDR cancer cells. The present review focuses primarily on the structural features, design strategies, and structure-activity relationships (SAR) of these compounds.

Substrate controlled, regioselective carbopalladation for the one-pot synthesis of C4-substituted tetrahydroisoquinoline analogues

6-Exo-trig cyclization reaction through regioselective carbopalladation was demonstrated with N-(2-halobenzyl)-N-allylamines to furnish the corresponding C4-substituted tetrahydroisoquinoline derivatives.