Multidrug Resistance In Cancer Cells Research Articles

Antiproliferative Effect of N-Heterocyclo-Coumarin Derivatives against Multidrug-Resistant Cells.

Chemotherapy refers principally to the use of small molecules to treat cancer, and natural product derivatives have been main sources of clinically using anticancer drugs. While the coumarin skeleton does not inhibit cell growth, its derivatives are often active, and numerous coumarins have been examined for antiproliferative activity against human cancer cell lines. In this study, 16 novel coumarin derivatives (1, 1a-5a, 1b, 2b, 6b, 7b, 8-13) with attached N-heterocycles, including aminopyrrolidine, aminopiperidine, aminoazepane, and indoline, were prepared and ultimately esterified or amidated with alcohols or amines, respectively. All synthesized N-heterocycles containing coumarin derivatives with alcohols, amines, and carboxylic acids were assessed for antiproliferative activity against several human cancer cell lines, containing triple-negative breast cancer (TNBC) as well as a P-glycoprotein (P-gp) overexpressing multidrug-resistant (MDR) KB subline KB-VIN. Five coumarin derivatives (3a-5a, 12, 13) showed no effect (IC50 >40 µM) against all tested cell lines. In contrast, derivative 1a showed broad-spectrum activity against four cell lines, while 1b and 10 were nearly twice as selective for KB-VIN cells as the parent KB. The coumarin derivatives 1a, 1b, and 10 were optimal for antiproliferative activity in this study and could provide a new avenue for overcoming MDR tumors. Derivatives 1a, 1b, and 10 showed MDR cell-selective antiproliferative activity, indicating that N-heterocycle-coumarins exert previously unexplored bioactivity with selective action on MDR cancer cells.

Detection of Single Non-small Cell Lung Cancer Cell Multidrug Resistance with Single-Cell Bioanalyzer.

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer death in the world. Despite the development of various lung cancer treatment methods, including surgery, radiation therapy, endocrine therapy, immunotherapy, and gene therapy, chemotherapy remains the most common approach for treating cancer. The risk of tumors acquiring resistance to chemotherapy remains a significant hurdle to the use of this approach for the successful treatment of various types of cancer. The majority of cancer-related deaths are related to metastasis. Circulating tumor cells (CTCs) are cells that have been detached from the primary tumor or have metastasized and entered the circulation. CTCs can cause metastases in various organs by reaching them through the bloodstream. The CTCs exist in peripheral blood as single cells or as oligoclonal clusters of tumor cells along with platelets and lymphocytes. The detection of CTCs is an important component of liquid biopsy which aids in the diagnosis, treatment, and prognosis of cancer. Here, we describe a method for extracting CTCs from the tumor of patients and using the microfluidic single-cell technique to study the inhibition of multidrug resistance due to drug efflux on a single cancer cell, to propose novel methods that can provide clinicians with more appropriate choices in their diagnostic and treatment approaches.

Differential dynamics and direct interaction of bound ligands with lipids in multidrug transporter ABCG2

ABCG2 is an ATP-binding cassette (ABC) transporter that extrudes a wide range of xenobiotics and drugs from the cell and contributes to multidrug resistance in cancer cells. Following our recent structural characterization of topotecan-bound ABCG2, here, we present cryo-EM structures of ABCG2 under turnover conditions in complex with a special modulator and slow substrate, tariquidar, in nanodiscs. The structures reveal that similar to topotecan, tariquidar induces two distinct ABCG2 conformations under turnover conditions (turnover-1 and turnover-2). μs-scale molecular dynamics simulations of drug-bound and apo ABCG2 in native-like lipid bilayers, in both topotecan- and tariquidar-bound states, characterize the ligand size as a major determinant of its binding stability. The simulations highlight direct lipid-drug interactions for the smaller topotecan, which exhibits a highly dynamic binding mode. In contrast, the larger tariquidar occupies most of the available volume in the binding pocket, thus leaving little space for lipids to enter the cavity and interact with it. Similarly, when simulating ABCG2 in the apo inward-open state, we also observe spontaneous penetration of phospholipids into the binding cavity. The captured phospholipid diffusion pathway into ABCG2 offers a putative general path to recruit any hydrophobic/amphiphilic substrates directly from the membrane. Our simulations also reveal that ABCG2 rejects cholesterol as a substrate, which is omnipresent in plasma membranes that contain ABCG2. At the same time, cholesterol is found to prohibit the penetration of phospholipids into ABCG2. These molecular findings have direct functional ramifications on ABCG2's function as a transporter.

Metal Complexes of a 5-Nitro-8-Hydroxyquinoline-Proline Hybrid with Enhanced Water Solubility Targeting Multidrug Resistant Cancer Cells.

Multidrug resistance (MDR) in cancer is one of the major obstacles of chemotherapy. We have recently identified a series of 8-hydroxyquinoline Mannich base derivatives with MDR-selective toxicity, however with limited solubility. In this work, a novel 5-nitro-8-hydroxyquinoline-proline hybrid and its Rh(η5-C5Me5) and Ru(η6-p-cymene) complexes with excellent aqueous solubility were developed, characterized, and tested against sensitive and MDR cells. Complex formation of the ligand with essential metal ions was also investigated using UV-visible, circular dichroism, 1H NMR (Zn(II)), and electron paramagnetic resonance (Cu(II)) spectroscopic methods. Formation of mono and bis complexes was found in all cases with versatile coordination modes, while tris complexes were also formed with Fe(II) and Fe(III) ions, revealing the metal binding affinity of the ligand at pH 7.4: Cu(II) > Zn(II) > Fe(II) > Fe(III). The ligand and its Rh(III) complex displayed enhanced cytotoxicity against the resistant MES-SA/Dx5 and Colo320 human cancer cell lines compared to their chemosensitive counterparts. Both organometallic complexes possess high stability in solution, however the Ru(II) complex has lower chloride ion affinity and slower ligand exchange processes, along with the readiness to lose the arene ring that is likely connected to its inactivity.

Metal-organic framework for biomimetic nitric oxide generation and anticancer drug delivery

The potential therapeutic implications of nitric oxide (NO) have drawn a great deal of interest for reversing multidrug resistance (MDR) in cancer; however, previous strategies utilized unstable or toxic NO donors often oxidized by the excessive addition of reactive oxygen species, leading to unexpected side effects. Therefore, this study proposed a metal-organic framework (MOF), Porous coordination network (PCN)-223-Fe, to be loaded with a biocompatible NO donor, L-arginine (L-arg; i.e., PCN-223-Fe/L-arg). This specific MOF possesses a ligand of Fe-porphyrin, a biomimetic catalyst. Thus, with PCN-223-Fe/L-arg, L-arg was released in a sustained manner, which generated NO by a catalytic reaction between L-arg and Fe-porphyrin in PCN-223-Fe. Through this biomimetic process, PCN-223-Fe/L-arg could generate sufficient NO to reverse MDR at the expense of hydrogen peroxide already present and highly expressed in cancer environments. For treatment of MDR cancer, this study also proposed PCN-223-Fe loaded with an anticancer drug, irinotecan (CPT-11; i.e., PCN-223-Fe/CPT-11), to be formulated together with PCN-223-Fe/L-arg. Owing to the synergistic effect of reversed MDR by NO generation and sustained release of CPT-11, this combined formulation exhibited a higher anticancer effect on MDR cancer cells (MCF-7/ADR). When intratumorally injected in vivo, coadministration of PCN-223-Fe/L-arg and PCN-223-Fe/CPT-11 greatly suppressed tumor growth in nude mice bearing MDR tumors.

Xylochemical Synthesis and Biological Evaluation of the Orchidaceous Natural Products Isoarundinin I, Bleochrin F, Blestanol K, and Pleionol.

The first total syntheses of the orchid-derived natural products isoarundinin I (1), (±)-bleochrin F ((±)-2), (±)-blestanol K ((±)-3), and (±)-pleionol ((±)-4) from renewable starting materials are reported, along with the evaluation of their biological activities. The total syntheses were based on regioselective aromatic bromination reactions in combination with a key acid-promoted regioselective intramolecular cyclization. The biological results suggest that isoarundinin I (1), (±)-blestanol K ((±)-3), and (±)-pleionol ((±)-4) have the potential to inhibit the growth of both sensitive and multidrug-resistant cancer cells.

Alpha-1 antitrypsin expression is upregulated in multidrug-resistant cancer cells.

Identification of the signature molecular profiles involved in therapy resistance is of vital importance in developing new strategies for treatments and disease monitoring. Protein alpha-1 antitrypsin (AAT, encoded by SERPINA1 gene) is an acute-phase protein, and its high expression has been linked with unfavorable clinical outcome in different types of cancer; however, data on its involvement in therapy resistance are still insufficient. We analyzed SERPINA1 mRNA expression in three different multidrug-resistant (MDR) cell lines-U87-TxR, NCI-H460/R, and DLD1-TxR-and in U87 cells grown in alginate microfibers as a 3D cellular model of glioblastoma. Expression of IL-6 as a major modulator of SERPINA1 was also analyzed. Additionally, AAT protein expression in MDR cells was analyzed by immunofluorescence. SERPINA1 gene expression and AAT protein expression were significantly upregulated in all the tested MDR cell lines compared with their sensitive counterparts. Moreover, SERPINA1 was significantly upregulated in 3D models of glioblastoma, previously found to have upregulated drug-resistance-related gene expression compared with 2D cells. With the exception of NCI-H460/R, in all cell lines as well as in a 3D model of U87 cells, increase in SERPINA1 expression correlated with the increase in IL-6 expression. Our results indicate that AAT could be utilized as a biomarker of therapy resistance in cancer; however, further studies are needed to elucidate the mechanisms driving AAT upregulation in therapy resistance and its biological significance in this process.

Efforts in Bioprospecting Research: A Survey of Novel Anticancer Phytochemicals Reported in the Last Decade

Bioprospecting natural products to find prominent agents for medical application is an area of scientific endeavor that has produced many clinically used bioactive compounds, including anticancer agents. These compounds come from plants, microorganisms, and marine life. They are so-called secondary metabolites that are important for a species to survive in the hostile environment of its respective ecosystem. The kingdom of Plantae has been an important source of traditional medicine in the past and is also enormously used today as an exquisite reservoir for detecting novel bioactive compounds that are potent against hard-to-treat maladies such as cancer. Cancer therapies, especially chemotherapies, are fraught with many factors that are difficult to manage, such as drug resistance, adverse side effects, less selectivity, complexity, etc. Here, we report the results of an exploration of the databases of PubMed, Science Direct, and Google Scholar for bioactive anticancer phytochemicals published between 2010 and 2020. Our report is restricted to new compounds with strong-to-moderate bioactivity potential for which mass spectroscopic structural data are available. Each of the phytochemicals reported in this review was assigned to chemical classes with peculiar anticancer properties. In our survey, we found anticancer phytochemicals that are reported to have selective toxicity against cancer cells, to sensitize MDR cancer cells, and to have multitarget effects in several signaling pathways. Surprisingly, many of these compounds have limited follow-up studies. Detailed investigations into the synthesis of more functional derivatives, chemical genetics, and the clinical relevance of these compounds are required to achieve safer chemotherapy.

Nanoliposomal C6-Ceramide Exhibits Synergistic Anti-Cancer Activity with a Small Molecule Agonist of PP2A in Chronic Lymphocytic Leukemia

The introduction of targeted therapies, including venetoclax (inhibitor of Bcl-2) and ibrutinib (inhibitor of Bruton's tyrosine kinase), has significantly advanced treatment of non-Hodgkin's lymphoma, particularly Chronic Lymphocytic Leukemia (CLL) and Mantle Cell Lymphoma (MCL). However, patients treated with ibrutinib, venetoclax, or the combination of ibrutinib and venetoclax are likely to exhibit treatment relapse. We have previously published that microenvironmental factors can generate anti-apoptotic resistance to combinatorial ibrutinib/venetoclax in both CLL and MCL models via NF-kB-dependent upregulation of anti-apoptotic proteins (Mcl-1 and Bcl-xL) (Jayappa et al. 2017). We have recently published the discovery of phenotypically similar drug resistant CLL cells that overexpress multiple anti-apoptotic proteins in patients de novo. These cells were enriched during treatment with venetoclax, suggesting this pool of resistant persister cells could be a source of treatment failure (Jayappa et al. 2021). We have previously formulated a non-toxic C6-ceramide nanoliposome (CNL) that greatly improves bioavailability of this bioactive sphingolipid and exerts anti-cancer activity in vivo, including CLL cell line that exhibits multidrug resistance phenotype (Lindsay et al. 2013). Thus, CNL-based novel therapies could hold promise for depleting the pool of multidrug resistant cancer cells in patients. In the current study, we screened CNL activity in CLL patient PBMC samples (N=15) using a flow cytometry-based cytotoxicity assay ex vivo. Our analysis revealed that CNL induced apoptotic/non-apoptotic cell death at overly high concentrations (EC50, 31 µM), prompting us to search for potential combinatorial therapies with enhanced toxicity profiles. To address this, we performed a combination drug screen with CNL as an anchor agent in a multidrug resistant CLL cell line (MEC1, p53-/mt) using a cell survival assay. Our analysis discovered exceptional synergistic interaction between CNL and a small molecule activator of Protein Phosphatase 2A (PP2A) (SMAP, DT061) in MEC1 cells [Bliss score (actual-Bliss predicted cytotoxicity): 56% (CNL, 6 µM; DT061, 12 µM)] and this synergistic behavior was further validated in primary CLL samples (N=5) ex vivo. Analyses using patient PBMC samples (N=3) have shown that the CNL and SMAP combination triggers apoptotic cell death with cleavage of caspase9, capase3, and PARP in CLL cells, while normal T lymphocytes in these samples were relatively less affected. At the molecular level, mutually reinforcing interactions between SMAP and CNL were observed. Using mass-spectrometric profiling of sphingolipids, we discovered that PP2A activation by SMAP modulates sphingolipid metabolism, leading to enhanced accumulation of C6-ceramide as well as synthesis of endogenous, pro-apoptotic sphingolipid molecules (C14- and C16-ceramides) in cells exposed to CNL. In addition, co-treatment with SMAP and CNL induced synergistic/additive downregulation of pBAD and cMyc, suggesting cMyc and/or Bad-dependent pathways could serve as node of convergence for synergistic interaction seen in these cells. In summary, we demonstrate that the CNL-SMAP combination displays exceptional synergy in CLL cells. At the molecular level, CNL and SMAP exhibit mutually reinforcing interactions that potentially converge on cMyc and Bad pathways, leading to synergistically increased apoptotic death in these cells. We intend to further characterize the role of cMyc and/or Bad pathway in synergistic interaction and assess the in vivo safety/efficacy of CNL-SMAP combination using a CLL xenograft mouse model. Collectively, this work provides the basis for further testing of this combination in in vivo models.

Hydroxygenkwanin Improves the Efficacy of Cytotoxic Drugs in ABCG2-Overexpressing Multidrug-Resistant Cancer Cells.

Hydroxygenkwanin, a flavonoid isolated from the leaves of the Daphne genkwa plant, is known to have pharmacological properties; however, its modulatory effect on multidrug resistance, which is (MDR) mediated by ATP-binding cassette (ABC) drug transporters, has not been investigated. In this study, we examine the interaction between hydroxygenkwanin, ABCB1, and ABCG2, which are two of the most well-characterized ABC transporters known to contribute to clinical MDR in cancer patients. Hydroxygenkwanin is not an efflux substrate of either ABCB1 or ABCG2. We discovered that, in a concentration-dependent manner, hydroxygenkwanin significantly reverses ABCG2-mediated resistance to multiple cytotoxic anticancer drugs in ABCG2-overexpressing multidrug-resistant cancer cells. Although it inhibited the drug transport function of ABCG2, it had no significant effect on the protein expression of this transporter in cancer cells. Experimental data showing that hydroxygenkwanin stimulates the ATPase activity of ABCG2, and in silico docking analysis of hydroxygenkwanin binding to the inward-open conformation of human ABCG2, further indicate that hydroxygenkwanin sensitizes ABCG2-overexpressing cancer cells by binding to the substrate-binding pocket of ABCG2 and attenuating the transport function of ABCG2. This study demonstrates the potential use of hydroxygenkwanin as an effective inhibitor of ABCG2 in drug combination therapy trials for patients with tumors expressing higher levels of ABCG2.

New Dual P-Glycoprotein (P-gp) and Human Carbonic Anhydrase XII (hCA XII) Inhibitors as Multidrug Resistance (MDR) Reversers in Cancer Cells.

In a continuing search of dual P-gp and hCA XII inhibitors, we synthesized and studied new N,N-bis(alkanol)amine aryl diester derivatives characterized by the presence of a coumarin group. These hybrids contain both P-gp and hCA XII binding groups to synergistically overcome the P-gp-mediated multidrug resistance (MDR) in cancer cells expressing both P-gp and hCA XII. Indeed, hCA XII modulates the efflux activity of P-gp and the inhibition of hCA XII reduces the intracellular pH, thereby decreasing the ATPase activity of P-gp. All compounds showed inhibitory activities on P-gp and hCA XII proteins taken individually, and many of them displayed a synergistic effect in HT29/DOX and A549/DOX cells that overexpress both P-gp and hCA XII, being more potent than in K562/DOX cells overexpressing only P-gp. Compounds 5 and 14 were identified as promising chemosensitizer agents for selective inhibition in MDR cancer cells overexpressing both P-gp and hCA XII.

Ifosfamide-Loaded Cubosomes: An Approach to Potentiate Cytotoxicity against MDA-MB-231 Breast Cancer Cells

Background: Ifosfamide (IFS) is proved efficacious against breast cancer, an enormously diagnosed cancer across the globe. However, the clinical efficacy of IFS is limited owing to its hydrophilicity, less stability, and dose-dependent toxicities. Therefore, the primary goal of the present research was to develop IFS-loaded cubosomes with improved anticancer efficacy and reduced dose-dependent toxicities.
 Methods: The IFS-cubosomes were optimized using a 32 factorial design based on IFS content and zeta potential. The optimized cubosomal dispersion was further assessed for particle size, in vitro IFS release, haemolysis, cytotoxicity, cellular uptake and physical stability.
 Results: The optimized IFS-cubosomal dispersion exhibited maximum IFS content (89.75±4.3%) and better zeta potential value (-40.0±1.6 mV), and size in nanometer. Moreover, IFS-cubosomes retarded IFS release (about 91 %) after 12 h than plain IFS solution (>99 % within 2 h). The IFS-cubosomes displayed lower haemolysis (3.7±0.79%) towards human RBCs. Besides, the in vitro cytotoxicity of IFS-cubosomes was noticed to be substantially higher (IC50: 0.64±0.08 µM) than plain IFS solution (IC50: 1.46±0.21 µM) against multi-drug resistant (MDR) breast cancer (MDA-MB-231) cells. DAPI staining revealed death of IFS-cubosomes treated cells mainly by apoptosis. The cubosomes showed increased uptake by cancer cells. Furthermore, IFS-cubosomes were found to be more stable at refrigeration temperature than at room temperature.
 Conclusion: Thus, IFS-cubosomes could be a novel avenue in the treatment of breast cancer with improved anticancer efficacy and reduced toxicity. However, further in vivo investigations are desired to validate these claims.

Reversal of multidrug resistance by Fissistigma latifolium–derived chalconoid 2-hydroxy-4,5,6-trimethoxydihydrochalcone in cancer cell lines overexpressing human P-glycoprotein

Cancer treatment is an evolving field with various challenges to clinical practice. One unresolved problem in this field is multidrug resistance (MDR) mediated by ABC efflux transporters, particularly P-glycoprotein (P-gp). In this study, by prescreening compounds, we identified the potential of a dihydrochalcone compound, 2-hydroxy-4,5,6-trimethoxydihydrochalcone, for P-gp inhibition. Therefore, we investigated its ability to inhibit P-gp and reverse P-gp-mediated MDR, as well as the underlying mechanisms. The P-gp-inhibitory effects of 2-hydroxy-4,5,6-trimethoxydihydrochalcone were investigated as follows. A P-gp efflux assay and an ATPase assay were used to understand the modulatory mechanisms in the drug-binding and ATP-binding areas, respectively. Prominent reversal effects observed in MDR cancer cell lines; thus, reversal, cytotoxicity, cell cycle, apoptosis, and reactive oxygen species assays were conducted to investigate the underlying mechanism. The results indicated that 2-hydroxy-4,5,6-trimethoxydihydrochalcone functionally inhibited P-gp in a noncompetitive manner, and this inhibition was unrelated to expression. In addition, 2-hydroxy-4,5,6-trimethoxydihydrochalcone served as an ATPase stimulator but not as a P-gp substrate. Moreover, a low binding energy of − 6.85 kcal/mol and one hydrogen bond were obtained, indicating that 2-hydroxy-4,5,6-trimethoxydihydrochalcone has a high affinity for P-gp. P-gp-mediated MDR was reversed by 31.6 μM 2-hydroxy-4,5,6-trimethoxydihydrochalcone in combination with paclitaxel, with a reversal fold value of 379.42. In conclusion, this study provides evidence of the ability of 2-hydroxy-4,5,6-trimethoxydihydrochalcone to inhibit P-gp and reverse MDR.

Insights of ethyl acetate fraction from Vassobia breviflora in multidrug-resistant bacteria and cancer cells: from biological to therapeutic

ABSTRACT Cancer and infectious diseases are among the leading causes of death in the world. Despite the diverse array of treatments available, challenges posed by resistance, side effects, high costs, and inaccessibility persist. In the Solanaceae plant family, few studies with Vassobia breviflora species relating to biological activity are known, but promising results have emerged. The phytochemicals present in the ethyl acetate fraction were obtained using ESI-MS-QTOF, and the antioxidants assays 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radical capture (ABTS), plasma ferric reduction capacity (FRAP), and total antioxidant capacity (TAC). Cytotoxic activity was evaluated by MTT, Neutral Red, and lactate dehydrogenase (LDH) released. The production of reactive oxygen species, nitric oxide, and purinergic enzymes was also investigated. Antibacterial activity was measured through minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antibiofilm activity, in addition to genotoxicity in plasmid DNA. Five major masses were identified D-glucopyranose II, allyl disulfide, γ-lactones, pharbilignoside, and one mass was not identified. V. breviflora exhibited relevant antioxidant and cytotoxic activity against the HeLa cell line and enhanced expression effect in modulation of purinergic signaling. Antibacterial activities in the assays in 7 ATCC strains and 8 multidrug-resistant clinical isolates were found. V. breviflora blocked biofilm formation in producing bacteria at the highest concentrations tested. However, there was no plasmid DNA cleavage at the concentrations tested. Data demonstrated that V. breviflora exhibited an antioxidant effect through several methods and proved to be a promising therapeutic alternative for use against tumor cells via purinergic signaling and multidrug-resistant microorganisms, presenting an anti-biofilm effect.

Three new cytotoxic annonaceous acetogenins from the seeds of Annona squamosa

Three new annonaceous acetogenins, annotemoyin L (1), annotemoyin Y (2) and annotemoyin X, (3) were isolated from the seeds of Annona squamosa Linn. Their structures were ascertained by chemical methods and spectral data. The cytotoxic activities of compounds against three multidrug-resistant cancer cell lines were evaluated, and compound 3 exerted strong cytotoxicity against SMMC 7721/ADR (IC50 0.163 μM), A549/T (IC50 0.064 μM) and MCF-7/ADR (IC50 0.057 μM).

Molecular design, synthesis and biological evaluation of novel 1,2,5-trisubstituted benzimidazole derivatives as cytotoxic agents endowed with ABCB1 inhibitory action to overcome multidrug resistance in cancer cells

Multidrug resistance (MDR) is a leading cause for treatment failure in cancer patients. One of the reasons of MDR is drug efflux by ATP-binding cassette (ABC) transporters in eukaryotic cells especially ABCB1 (P-glycoprotein). In this study, certain novel 1,2,5-trisubstituted benzimidazole derivatives were designed utilising ligand based pharmacophore approach. The designed benzimidazoles were synthesised and evaluated for their cytotoxic activity towards doxorubicin-sensitive cell lines (CCRF/CEM and MCF7), as well as against doxorubicin-resistant cancer cells (CEM/ADR 5000 and Caco-2). In particular, compound VIII showed a substantial cytotoxic effect in all previously mentioned cell lines especially in doxorubicin-resistant CEM/ADR5000 cells (IC50 = 8.13 µM). Furthermore, the most promising derivatives VII, VIII and XI were tested for their ABCB1 inhibitory action in the doxorubicin-resistant CEM/ADR 5000 subline which is known for overexpression of ABCB1 transporters. The results showed that compound VII exhibited the best ABCB1 inhibitory activity at three tested concentrations (22.02 µM (IC50), 50 µM and 100 µM) in comparison to verapamil as a reference ABCB1 inhibitor. Such inhibition resulted in a synergistic effect and a massive decrease in the IC50 of doxorubicin (34.5 µM) when compound VII was used in a non-toxic dose in combination with doxorubicin in doxorubicin-resistant cells CEM/ADR 5000 (IC50(Dox+VII) = 3.81 µM). Molecular modelling studies were also carried out to explain the key interactions of the target benzimidazoles at the ABCB1 binding site. Overall the obtained results from this study suggest that 1,2,5-trisubstituted benzimidazoles possibly are promising candidates for further optimisation and development of potential anticancer agents with ABCB1 inhibitory activity and therefore overcome MDR in cancer cells.

Jatrophane diterpenoids from Euphorbia microcarpa (prokh.) krylov with multidrug resistance modulating activity

Eight undescribed jatrophane diterpenoids, namely euphomicrophane A-H, together with thirteen known diterpenes were isolated from the whole plant extracts of Euphorbia microcarpa (Prokh.) Krylov. Among them, euphomicrophane C and F were possessed the endo-type core structure that naturally rarely appeared. The structures of the purified undescribed compounds were established by extensive spectroscopic and spectrometric analysis, and the single-crystal X-ray diffraction analysis was used to determine the absolute configuration of euphomicrophane E, elusone A and euphorbesulin G. All the isolates were screened for their reversal abilities on P-glycoprotein-mediated multidrug resistant cancer cell line MCF-7/ADR. Compounds euphomicrophane G-H and 3β,7β,8α,9α,15β-pentaacetoxy-5β-benzoyloxyjatropha-6(17)-11E-dien-14-one were showed potential chemoreversal effect with reversal fold values 18.67, 17.15, and 16.76 at a concentration of 10.0 μM, being equal to or stronger than the positive drug verapamil (16.68).

5-Arylidenerhodanines as P-gp Modulators: An Interesting Effect of the Carboxyl Group on ABCB1 Function in Multidrug-Resistant Cancer Cells.

Multidrug resistance (MDR) is considered one of the major mechanisms responsible for the failure of numerous anticancer and antiviral chemotherapies. Various strategies to overcome the MDR phenomenon have been developed, and one of the most attractive research directions is focused on the inhibition of MDR transporters, membrane proteins that extrude cytotoxic drugs from living cells. Here, we report the results of our studies on a series newly synthesized of 5-arylidenerhodanines and their ability to inhibit the ABCB1 efflux pump in mouse T-lymphoma cancer cells. In the series, compounds possessing a triphenylamine moiety and the carboxyl group in their structure were of particular interest. These amphiphilic compounds showed over 17-fold stronger efflux pump inhibitory effects than verapamil. The cytotoxic and antiproliferative effects of target rhodanines on T-lymphoma cells were also investigated. A putative binding mode for 11, one of the most potent P-gp inhibitors tested here, was predicted by molecular docking studies and discussed with regard to the binding mode of verapamil.

Tumor pH-functionalized and charge-tunable nanoparticles for the nucleus/cytoplasm-directed delivery of oxaliplatin and miRNA in the treatment of head and neck cancer

Prospective tumor pH-responsive and charge-convertible nanoparticles have been utilized to reduce side effects and improve the active tumor-targeting ability and nuclear/cytoplasmic localization of chemo- and gene therapeutics for the treatment of head and neck cancer (HNC). Oxaliplatin (Oxa) is a third-generation platinum compound that prevents DNA replication. miR-320 may regulate cancer cell apoptosis, resistance, and progression. Innovative nanoparticles incorporating miR-320 and Oxa were modified with a ligand, cell-penetrating peptide, and nucleus-targeted peptide. The nanoparticles were coated with a charge/size-tunable shield to prevent peptide degradation and decoated at acidic tumor sites to expose peptides for active targeting. Results indicated that the designed nanoparticles exhibited a uniform size and satisfactory drug encapsulation efficiency. The nanoparticles displayed the pH-responsive release and uptake of Oxa and miR-320 into human tongue squamous carcinoma SAS cells. The nanoparticles successfully delivered Oxa and miR-320 to the nucleus and cytoplasm, respectively. This work is the first to demonstrate the concurrent intracellular modulation of the NRP1/Rac1, PI3K/Akt/mTOR, GSK-3β/FOXM1/β-catenin, P-gp/MRPs, KRAS/Erk/Oct4/Yap1, and N-cadherin/Vimentin/Slug pathways to inhibit the growth, progression, and multidrug resistance of cancer cells. In SAS-bearing mice, co-treatment with Oxa- and miR-320-loaded nanoparticles exhibited superior antitumor efficacy and remarkably decreased Oxa-associated toxicities. The nucleus/cytoplasm-localized nanoparticles with a tumor pH-sensitive and size/charge-adjustable coating may be a useful combinatorial spatiotemporal nanoplatform for nucleic acids and chemotherapeutics to achieve maximum therapeutic safety and efficacy against HNC. Statement of significanceInnovative nanoparticles incorporating miR-320 and oxaliplatin were modified with a ligand, cell-penetrating peptide, and nucleus-targeted peptide. The tumor pH-sensitive and charge/size-adjustable shield of polyglutamic acid–PEG protected against peptide degradation during systemic circulation. This work represents the first example of the concurrent intracellular modulation of the NRP1/Rac1, PI3K/Akt/mTOR, GSK-3β/FOXM1/β-catenin, P-gp/MRPs, KRAS/Erk/Oct4/Yap1, and N-cadherin/Vimentin/Slug pathways to inhibit cancer cell growth, cancer cell progression, and multidrug resistance simultaneously. The versatile nanoparticles with a tumor pH-functionalized coating could deliver chemotherapeutics and miRNA to the nucleus/cytoplasm. The nanoparticles successfully reduced chemotherapy-associated toxicities and maximized the antitumor efficacy of combinatorial therapy against head and neck cancer.

Synthesis and Characterization of Palmitoyl-block-poly(methacryloyloxyethyl phosphorylcholine) Polymer Micelles for Anticancer Drug Delivery.

We report the synthesis and characterization of an amphiphilic polymer comprising a hydrophobic palmitoyl (Pal) group and a zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC) block, which is capable of forming micelles as a drug carrier system for delivering hydrophobic anticancer drugs such as doxorubicin (DOX). We hypothesize that the sharp polarity contrast between the Pal domain and the pMPC block would strengthen the micelles and improve the drug loading capacity, while the pMPC shells improve the micelle stability and cellular uptake efficiency. In this study, the Pal-pMPC polymer was characterized and compared with a Pal-poly(ethylene glycol) (Pal-PEG) polymer in terms of their micelle formation, cytotoxicity, and drug loading of DOX. The DOX-loaded Pal-pMPC micelles were further evaluated for the cellular uptake and anticancer activities in cell culture systems including the non-multidrug-resistance HeLa cell line and the multidrug-resistance AT3B-1 cell line. The results showed that the Pal-pMPC polymer had a minimal toxicity. The Pal-pMPC micelles exhibited higher drug loading capacity and enhanced cellular internalization efficiency compared to micelles formed by the Pal-PEG polymer. It was also found that DOX-loaded Pal-pMPC micelles exhibited a more efficient anticancer effect than Pal-PEG micelles in multidrug-resistance cancer cells in an environment with fetal bovine serum.