Natural alkaloids as P-gp inhibitors for multidrug resistance reversal in cancer

Palladium-catalyzed Ugi-type reaction of 2-iodoanilines with isocyanides and carboxylic acids affording N-acyl anthranilamides

The first palladium-catalyzed Ugi-type multicomponent reaction for the synthesis of N-acyl anthranilamides from isocyanides, 2-iodoanilines and carboxylic acids has been developed. This method provides expeditious and highly efficient access to structurally diverse N-acyl anthranilamides from readily available starting materials with good functional group compatibility. The utility of this method has been demonstrated by the late stage functionalization of two commercial drugs: Flurbiprofen and Loxoprofen.

Nanomedicine to Overcome Multidrug Resistance Mechanisms in Colon and Pancreatic Cancer: Recent Progress

The development of drug resistance is one of the main causes of cancer treatment failure. This phenomenon occurs very frequently in different types of cancer, including colon and pancreatic cancers. However, the underlying molecular mechanisms are not fully understood. In recent years, nanomedicine has improved the delivery and efficacy of drugs, and has decreased their side effects. In addition, it has allowed to design drugs capable of avoiding certain resistance mechanisms of tumors. In this article, we review the main resistance mechanisms in colon and pancreatic cancers, along with the most relevant strategies offered by nanodrugs to overcome this obstacle. These strategies include the inhibition of efflux pumps, the use of specific targets, the development of nanomedicines affecting the environment of cancer-specific tissues, the modulation of DNA repair mechanisms or RNA (miRNA), and specific approaches to damage cancer stem cells, among others. This review aims to illustrate how advanced nanoformulations, including polymeric conjugates, micelles, dendrimers, liposomes, metallic and carbon-based nanoparticles, are allowing to overcome one of the main limitations in the treatment of colon and pancreatic cancers. The future development of nanomedicine opens new horizons for cancer treatment.

A New Chalcone Derivative C49 Reverses Doxorubicin Resistance in MCF-7/DOX Cells by Inhibiting P-Glycoprotein Expression

Objective: C49 is a chalcone derivative. The aim of the current study is to illuminate the efficacy of C49 in reversing multidrug resistance (MDR) in MCF-7/DOX cells and its underlying molecular mechanism. Methods: The cytotoxic effects of C49 on MCF-7/DOX cells were evaluated by MTT assay using different concentration (0-250 μmol/L) of C49. Cell proliferation was evaluated by colony formation assay. Cell death was examined by morphological analysis using Hoechst 33,258 staining. Flow cytometry and immunofluorescence were utilized to evaluate the intracellular accumulation of doxorubicin (DOX) and cell apoptosis. The differentially expressed genns between MCF-7 and MCF-7/DOX cells were analyzed by GEO database. The expression of PI3K/Akt pathway proteins were assessed by Western blot The activities of C49 combined with DOX was evaluated via xenograft tumor model in female BALB/c nude mice. Results: C49 inhibited the growth of MCF-7 cells (IC50 = 59.82 ± 2.10 μmol/L) and MCF-7/DOX cells (IC50 = 65.69 ± 8.11 μmol/L) with dosage-dependent and enhanced the cellular accumulation of DOX in MCF-7/DOX cells. The combination of C49 and DOX inhibited cell proliferation and promoted cell apoptosis. MCF-7/DOX cells regained drug sensibility with the combination treatment through inhibiting the expression of P-gp, p-PI3K and p-Akt proteins. Meanwhile, C49 significantly increased the anticancer efficacy of DOX in vivo. Conclusion: C49 combined with DOX restored DOX sensitivity in MCF-7/DOX cells through inhibiting P-gp protein.

pH and ROS sequentially responsive podophyllotoxin prodrug micelles with surface charge-switchable and self-amplification drug release for combating multidrug resistance cancer

Multidrug resistance (MDR) is one of the main reasons for tumor chemotherapy failure. Podophyllotoxin (PPT) has been reported that can suppress MDR cancer cell growth; however, effective delivery of PPT to MDR cancer cells is challenged by cascaded bio-barriers. To effectively deliver PPT to MDR cancer cells, a PPT polymeric prodrug micelle (PCDMA) with the charge-conversion capability and self-acceleration drug release function are fabricated, which is composed of a pH and reactive oxygen species (ROS) sequentially responsive PPT-polymeric prodrug and an ROS generation agent, cucurbitacin B (CuB). After reach to tumor tissue, the surface charge of PCDMA could rapidly reverse to positive in the tumor extracellular environment to promote cellular uptake. Subsequently, the PCDMA could be degraded to release PPT and CuB in response to an intracellular high ROS condition. The released CuB is competent for generating ROS, which in turn accelerates the release of PPT and CuB. Eventually, the released PPT could kill MDR cancer cells. The in vitro and in vivo studies demonstrated that PCDMA was effectively internalized by cancer cells and produces massive ROS intracellular, rapid release drug, and effectively overcame MDR compared with the control cells, due to the tumor-specific weakly acidic and ROS-rich environment. Our results suggest that the pH/ROS dual-responsive PCDMA micelles with surface charge-reversal and self-amplifying ROS-response drug release provide an excellent platform for potential MDR cancer treatment.

miR-26a Reverses Multidrug Resistance in Osteosarcoma by Targeting MCL1

The multidrug resistance (MDR) acquired in human osteosarcoma is a huge obstacle for effective chemotherapy. Recently, microRNA-26a (miR-26a) has been associated with the pathogenesis and progression of osteosarcoma. However, whether it regulates MDR in osteosarcoma is unknown. We show here that miR-26a expression declines in chemoresistant osteosarcoma after neoadjuvant chemotherapy, and its expression correlates with clinical outcome. In addition, compared with sensitive parental cells, miR-26a expression also declines in osteosarcoma MDR cells, together suggesting a negative correlation between miR-26a expression and MDR development in osteosarcoma. We also show that the enforced expression of miR-26a reverses MDR in osteosarcoma cells, and conversely, miR-26a knockdown confers MDR in chemosensitive osteosarcoma cells treated with doxorubicin, methotrexate, or cisplatin. Mechanistically, miR-26a directly targets the pro-survival protein myeloid cell leukemia 1 (MCL1), and in turn, the enforced expression of MCL1 markedly antagonizes miR-26a-decreased MDR in osteosarcoma MDR cells, therefore demonstrating that miR-26a reverses MDR in osteosarcoma by targeting MCL1. Lastly, miR-26a reverses resistance to doxorubicin in osteosarcoma MDR cells xenografted in nude mice. Collectively, these results reveal a negative role and the underlying mechanism of miR-26a in the regulation of MDR in human osteosarcoma, implying a potential tactic of manipulating miR-26a for overcoming MDR in osteosarcoma chemotherapy.

Design, synthesis and in vitro anticancer research of novel tetrandrine and fangchinoline derivatives

Cancer treatment is one of the major public health issues in the world. Tetrandrine (Tet) and fangchinoline (d-Tet) are two bis-benzyl isoquinoline alkaloids extracted from Stephania tetrandra S. Moore, and their antitumor activities have been confirmed. However, the effective dose of Tet and d-Tet were much higher than that of the positive control and failed to meet clinical standards. Therefore, in this study, as a continuation of our previous work to study and develop high-efficiency and low-toxic anti-tumor lead compounds, twenty new Tet and d-Tet derivatives were designed, synthesized and evaluated as antitumor agents against six cancer cell lines (H460, H520, HeLa, HepG-2, MCF-7, SW480 cell lines) and BEAS-2B normal cells by CCK-8 analysis. Ten derivatives showed better cytotoxic effects than the parent fangchinoline, of which 4g showed the strongest cell growth inhibitory activity with an IC₅₀ value of 0.59 μM against A549 cells. Subsequently, the antitumor mechanism of 4g was studied by flow cytometry, Hoechst 33258, JC-1 staining, cell scratch, transwell migration, and Western blotting assays. These results showed that compound 4g could inhibit A549 cell proliferation by arresting the G2/M cell cycle and inhibiting cell migration and invasion by reducing MMP-2 and MMP-9 expression. Meanwhile, 4g could induce apoptosis of A549 cells through the intrinsic pathway regulated by mitochondria. In addition, compound 4g inhibited the phosphorylation of PI3K, Akt and mTOR, suggesting a correlation between blocking the PI3K/Akt/mTOR pathway and the above antitumor activities. These results suggest that compound 4g may be a future drug for the development of new potential drug candidates against lung cancer.

Combination treatment strategies with a focus on rosiglitazone and adriamycin for insulin resistant liver cancer

Insulin resistance promotes the occurrence of liver cancer and decreases its chemosensitivity. Rosiglitazone (ROSI), a thiazolidinedione insulin sensitiser, could be used for diabetes with insulin resistance and has been reported to show anticancer effects on human malignant cells. In this paper, we investigated the combination of ROSI and chemotherapeutics on the growth and metastasis of insulin-resistant hepatoma. In vitro assay, ROSI significantly enhanced the inhibitory effects of adriamycin (ADR) on the proliferation, autophagy and migration of insulin-resistant hepatoma HepG2/IR cells via downregulation of EGFR/ERK and AKT/mTOR signalling pathway. In addition, ROSI promoted the apoptosis of HepG2/IR cells induced by ADR. In vivo assay, high fat and glucose diet and streptozotocin (STZ) induced insulin resistance in mice by increasing the body weight, fasting blood glucose (FBG) level, oral glucose tolerance, fasting insulin level and insulin resistance index. Both the growth of mouse liver cancer hepatoma H22 cells and serum FBG level in insulin resistant mice were significantly inhibited by combination of ROSI and ADR. Thus, ROSI and ADR in combination showed a stronger anti-tumour effect in insulin resistant hepatoma cells accompanying with glucose reduction and might represent an effective therapeutic strategy for liver cancer accompanied with insulin resistant diabetes.

CD44 enhances adriamycin resistance in chronic myelogenous leukaemia cells K562

INTRODUCTION

To investigate CD44 effects on the adriamycin-resistant in chronic myelogenous leukaemia cells K562, we explored the role of CD44 in the K562 cells migration and apoptosis.

METHODS

GeneChip^® screening is used for elucidating various chemoresistance-related gene expression in the adriamycin-resistant leukaemia cells K562/ADR. We constructed K562/CD44 cells by transfection of an EGFP-SV40-CD44 plasmid, and adriamycin-resistant ability was confirmed by detecting migration and apoptosis-related proteins and mRNA expression using Western blotting and Real-time PCR respectively.

RESULTS

K562/CD44 cells were generated by the transfection of an EGFP-SV40-CD44 plasmid with high CD44 expression. mRNA expression levels of CD44 and P-glycoprotein (P-gp), along with the proliferation rate, were increased, while the apoptosis rate of K562/CD44 cells was decreased. Migration-associated proteins such as MMP-2 and MMP-9 were upregulated, whereas apoptosis-related protein Bax was downregulated and Bcl-2 protein was not significantly altered in the K562/CD44 cells.

CONCLUSIONS

CD44 might be involved in adriamycin resistance via regulation of P-gp, MMP-2, MMP-9, and Bcl-2/Bax.

Physcion-8-O-β-d-glucoside interferes with the nuclear factor-κB pathway and downregulates P-glycoprotein expression to reduce paclitaxel resistance in ovarian cancer cells

OBJECTIVE

This study assessed whether physcion-8-O-beta-D-monoglucoside (PG) sensitises paclitaxel (PTX)-resistant ovarian cancer cells and explored the underlying mechanism.

METHODS

Ovarian cancer SK-OV-3 cells were used to establish PTX-resistant SK-OV-3 (SK-OV-3/PTX) cells. The Cell Counting Kit-8 assay and crystal violet staining were used to determine cell viability. P-glycoprotein (P-gp) and nuclear factor (NF)-κB expression and cell distributions were detected using immunofluorescence. Cell apoptosis and protein expression changes were detected using flow cytometry and western blotting, respectively. Effect of PG in vivo was evaluated using a xenograft tumour model. P-gp expression in tumour tissues was detected using immunohistochemical staining.

KEY FINDINGS

PG (1-10 μm) did not significantly affect SK-OV-3/PTX cell proliferation but significantly downregulated P-gp expression. PG pretreatment (1-10 μm) enhanced PTX cytotoxicity. PG treatment decreased the quantity of phosphorylated-NF-κB p65 in SK-OV-3/PTX cell total proteins and upregulated IKBα expression. Simultaneously, it decreased NF-κB p65 levels in nuclear proteins. PG (1-10 μm) inhibited NF-κB p65 entry into the nucleus. PTX plus PG significantly inhibited SK-OV-3/PTX xenograft tumour growth. PG (1-10 μm) reduced P-gp expression in transplanted tumour tissue.

CONCLUSIONS

PG can enhance the sensitivity of PTX-resistant ovarian cancer cells SK-OV-3/PTX to PTX, and this effect is related to inhibiting NF-κB from entering the nucleus and down-regulating the expression of P-gp protein.

Plant-Derived Natural Products in Cancer Research: Extraction, Mechanism of Action, and Drug Formulation

Cancer is one of the main causes of death globally and considered as a major challenge for the public health system. The high toxicity and the lack of selectivity of conventional anticancer therapies make the search for alternative treatments a priority. In this review, we describe the main plant-derived natural products used as anticancer agents. Natural sources, extraction methods, anticancer mechanisms, clinical studies, and pharmaceutical formulation are discussed in this review. Studies covered by this review should provide a solid foundation for researchers and physicians to enhance basic and clinical research on developing alternative anticancer therapies.

Evodiamine inhibits high-fat diet-induced colitis-associated cancer in mice through regulating the gut microbiota

OBJECTIVE

High-fat diet is one of the main risk factors that disrupt the balance of gut microbiota, which eventually will induce colorectal cancer (CRC). Evodiamine (EVO) is a wildly used multifunctional traditional Chinese medicine extract. In this study, we investigated the role of gut microbiota in high-fat diet-propelled CRC and the potential of EVO for CRC chemoprevention.

METHODS

Gut microbiota, serum d-lactic acid and endotoxin from 38 patients with colon cancer and 18 healthy subjects were detected by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA). In addition, body mass index, phospho-signal transducer and activator of transcription 3 (p-STAT3) expression in cancer tissues and paracancerous tissues were detected by immunohistochemistry. A mouse intestinal inflammatory tumor model was established by azomethane/sodium dextran sulfate, followed by treatment with EVO and 5-aminosalicylic acid (ASA). Gut microbiota and inflammatory factors were detected by quantitative polymerase chain reaction, while serum d-lactic acid and endotoxin were detected by ELISA. Furthermore, cell proliferation, cell apoptosis, and interleukin (IL)-6/STAT3/P65 pathway were evaluated by 5-ethynyl-2'-deoxyuridine, terminal-deoxynucleotidyl transferase-mediated nick-end labeling, and Western blot assays.

RESULTS

In patients with colon cancer, the numbers of Enterococcus faecalis and Escherichia coli were increased, while those of Bifidobacterium, Campylobacter and Lactobacillus were decreased. Serum endotoxin and d-lactic acid levels and p-STAT3 levels were significantly increased. In the mouse model, both EVO and ASA inhibited tumor formation, decreased the proliferation of tumor cells, and induced apoptosis of tumor cells. Compared with the control group, the numbers of E. faecalis and E. coli were decreased, while Bifidobacterium, Campylobacter and Lactobacillus numbers were increased. In the EVO group, serum endotoxin and d-lactic acid levels and inflammatory factors were significantly decreased. Further, the IL6/STAT3/P65 signaling pathway was inhibited in the EVO group.

CONCLUSION

EVO may inhibit the occurrence of colon cancer by regulating gut microbiota and inhibiting intestinal inflammation. The potential mechanism involves inhibition of the IL6/STAT3/P65 signaling pathway, revealing its potential therapeutic significance in clinical applications.

The Effects of Traditional Chinese Medicine on P-Glycoprotein-Mediated Multidrug Resistance and Approaches for Studying the Herb-P-Glycoprotein Interactions

As a member of the ATP-dependent membrane transport proteins, P-Glycoprotein (P-gp) is known to pump substrates out of cells using an ATP-dependent mechanism. The overexpression of P-gp in tumor cells reduces the intracellular drug concentrations, which decreases the efficacy of extensive antitumor drugs and leads to multidrug resistance (MDR) clinically. The combination of anticancer drugs with P-gp inhibitor has been an attractive and promising strategy to reverse MDR in cancer treatment. However, nonspecific or nonselective distribution of P-gp inhibitors to nontarget organs is one of the most fatal shortcomings in clinical application. Thus, there is an urgent need for effective and nontoxic MDR reversal agents, particularly in P-gp-mediated MDR. Traditional Chinese medicine (TCM) natural products may prove less toxic for use in P-gp inhibition to promote MDR reversal. P-gp modulatory effects have been previously demonstrated using selected TCM, including the flavonoid, alkaloid, terpenoid, coumarin, and quinonoid compounds, and some Chinese medicine extracts. Moreover, the approaches for screening active components from TCM are necessary, and these approaches face challenges. At present, the approaches to study the interaction between TCM and P-gp are divided into in vitro, in vivo, and in silico methods. This review will provide an overview and update on the role of TCM in overcoming P-gp-mediated MDR and the approaches to study the interaction between TCM and P-gp. SIGNIFICANCE STATEMENT: This review summarized some traditional Chinese medicines identified to have a modulatory effect on P-gp, including flavonoids, alkaloids, terpenoids, coumarins, quinonoid compounds, and some Chinese medicine extracts, and it introduced possible mechanisms. The approaches to study the interaction between TCM and P-gp are divided into in vitro, in vivo, and in silico methods.

Drug delivery systems based on CD44-targeted glycosaminoglycans for cancer therapy

The polysaccharide-based biomaterials hyaluronic acid (HA) and chondroitin sulfate (CS) have aroused great interest for use in drug delivery systems for tumor therapy, as they have outstanding biocompatibility and great targeting ability for cluster determinant 44 (CD44). In addition, modified HA and CS can self-assemble into micelles or micellar nanoparticles (NPs) for targeted drug delivery. This review discusses the formation of HA- and CS-based NPs, and various types of CS-based NPs including CS-drug conjugates, CS-polymer NPs, CS-small molecule NPs, polyelectrolyte nanocomplexes (PECs), CS-metal NPs, and nanogels. We then focus on the applications of HA- and CS-based NPs in tumor chemotherapy, gene therapy, photothermal therapy (PTT), photodynamic therapy (PDT), sonodynamic therapy (SDT), and immunotherapy. Finally, this review is expected to provide guidelines for the development of various HA- and CS-based NPs used in multiple cancer therapies.

The effects of pharmacological interventions, exercise, and dietary supplements on extra-cardiac radioactivity in myocardial perfusion single-photon emission computed tomography imaging

Myocardial perfusion imaging (MPI) as an imaging modality plays a key role in the monitoring of patients with cardiovascular disease. MPI enables the assessment of cardiovascular disease, the effectiveness of therapy, and viable myocardial tissue. However, MPI suffers from some downfalls and limitations, which can influence its clinical applications. These limitations can arise from the patient's condition, equipment, or the actions of the technologist. In this review, we mainly focused on the different effective parameters on radioactivity uptake of organs including liver, intestines, stomach, and gall bladder and how they affect the quality of the acquired images in nuclear medicine. More importantly, we cover how different suggested medicines, foods and exercise alleviative this problem.

Chromene- and Quinoline-3-Carbaldehydes: Useful Intermediates in the Synthesis of Heterocyclic Scaffolds

Chromenes and quinolines are recognized as important scaffolds in medicinal chemistry. Herein, the efficient use of chromene- and quinoline-3-carbaldehydes to synthesize other valuable heterocycles is described. These carbaldehydes are obtained in excellent yields through the Vilsmeyer-Haack reaction of flavanones and azaflavanones. Protocols towards the synthesis of new heterocycles, such as 3H-chromeno[3–c]quinolines, (Z/E)-2-aryl-4-chloro-3-styryl-2H-chromenes, and (E)-2-aryl-4-chloro-3-styrylquinoline-1(2H)-carbaldehydes were established. Altogether, we demonstrate the value of chromene- and quinoline-3-carbaldehydes as building blocks.

Pyrimidine: A promising scaffold for optimization to develop the inhibitors of ABC transporters

The multidrug resistance (MDR) phenomenon in cancer cells is the major obstacle leading to failure of chemotherapy accompanied by the feature of intractable and recurrence of cancers. As significant contributors that cause MDR, ABC superfamily proteins can transport the chemotherapeutic drugs out of the tumor cells by the energy of adenosine triphosphate (ATP) hydrolysis, thereby reducing their intracellular accumulation. The ABC transports like ABCB1, ABCC1 and ABCG2 have been extensively studied to develop modulators for overcoming MDR. To date, no reversal agents have been successfully marketed for clinical application, and little information about the ABC proteins bound to specific inhibitors is known, which make the design of MDR inhibitors with potency, selectivity and low toxicity a major challenge. In recent years, it has been increasingly recognized that pyrimidine-based derivatives have the potential for reversing ABC-mediated MDR. In this review, we summarized the pyrimidine-based inhibitors of ABC transporters, and mainly focused on their structure optimizations, development strategies and structure-activity relationship studies in hope of providing a reference for medicinal chemists to develop new modulators of MDR with highly potency and fewer side effects.

Reversal of P-glycoprotein-mediated multidrug resistance by novel curcumin analogues in paclitaxel-resistant human breast cancer cells

Multidrug resistance (MDR) is a major obstacle for successful cancer chemotherapy, and the main cause of MDR has been attributed to overexpression of P-glycoprotein (P-gp). In this present study, four P-gp modulators (E,E)-4,6-bis(styryl)-2-(substituted amino)-pyrimidines were evaluated for their activity in a breast cancer cell line overexpressing P-gp (LCC6MDR). The four modulators displayed significantly better P-gp modulating activity compared with the positive control verapamil (RF = 5.4), with a relative fold (RF) increase in activity ranging from 33.3 to 86.0. In contrast to compounds a and c that exhibited lower cytotoxicity, compounds b and d were nontoxic towards both cancer cells and normal cells, with IC50 values greater than 100 μmol/L. The qRT-PCR results demonstrated that after exposure to 2 μmol/L of compounds a, b, c, and d, the mRNA expression level of MDR1 in LCC6MDR cells decreased to 45%, 50%, 38%, and 51%, respectively. However, the Western-blot results indicated that compound c could reverse P-gp mediated MDR, but not via decreases in protein expression. DOX and Rh123 accumulation and efflux results further confirmed that the reversal of MDR activity happens via inhibition of P-gp efflux and increases in intracellular drug accumulation. These results demonstrated that compound c has low toxicity and is an efficient P-gp modulator, highlighting its potential as a promising candidate for P-gp-mediated reversal of MDR.

Sophoridine exerts tumor-suppressive activities via promoting ESRRG-mediated β-catenin degradation in gastric cancer

Background

As a natural alkaloid product isolated from Sophora alopecuroides. L, Sophoridine reshapes gastric cancer immune microenvironment via inhibiting chemotaxis and M2 polarization of tumor-associated macrophages (TAMs). However, the exact effects and underlying mechanism of Sophoridine on gastric cancer cells remains poorly known.

Methods

The potential anti-tumor effects of Sophoridine on gastric cancer cell lines, including AGS and SGC7901 cells, were detected by CCK-8, EDU and colony forming assay, immunofluorescence, transwell assay, and flow cytometry. Molecular mechanisms of Sophoridine were investigated by siRNA transfection, nuclear/cytoplasmic extraction and western blot. The synergistic effects of Sophoridine with cisplatin on gastric cancer cells were further investigated in in vitro functional studies.

Results

Sophoridine exhibited potent tumor-suppressive activities in gastric cancer cells, including inhibition of proliferation, colony formulation, migration and invasion, as well as induction of apoptosis. In addition, we further showed that Sophoridine induced G2/M cell cycle arrest via inhibiting double-stranded DNA breaks repair and enhanced the efficacy of cisplatin in gastric cancer cells. Molecular studies further revealed that Sophoridine promoted β-catenin degradation by enhancing Estrogen-related receptor gamma (ESRRG) expression, but not depended on ubiquitination-proteasome pathway, either TRIM33-mediated (GSK3β-independent) or altered GSK3β activity, and thus exerted potent tumor-suppressive activities.

Conclusion

Sophoridine depends on targeting ESRRG/β-catenin pathway to exert tumor-suppressive activities in gastric cancer cells and enhances the anti-tumor effect of cisplatin. Our study provided the promising preclinical anti-tumor evidence for the potential application of Sophoridine against gastric cancer.

Wilforine resensitizes multidrug resistant cancer cells via competitive inhibition of P-glycoprotein

BACKGROUND AND PURPOSE

Multidrug resistance (MDR) remains the main obstacle in cancer treatment and overexpression of P-glycoprotein (P-gp) is one of the most common causes of chemoresistance. The development of novel P-gp inhibitors from natural products is a prospective strategy to combat MDR cancers. Among the natural sesquiterpene compounds, sesquiterpene pyridine alkaloids exhibit various biological properties. Therefore, in the present study, we evaluated the modulatory effects of wilforine on P-gp expression and function. The molecular mechanisms and kinetic models of wilforine-mediated P-gp inhibition were further investigated.

METHODS

The human P-gp stable expression cells (ABCB1/Flp-In^TM-293) and human cervical cancer cells (sensitive: HeLaS3; MDR: KBvin) were used. The cell viability was assessed by SRB assay. The inhibitory effect of wilforine on P-gp efflux and the underlying mechanism were evaluated by assays for calcein-AM uptake, rhodamine123 and doxorubicin efflux, ATPase activity, real-time quantitative RT-PCR, apoptosis, and cell cycle analysis. Molecular docking was performed by the docking software CDOCKER with BIOVIA Discovery Studio 4.5 (D.S. 4.5).

RESULTS

We found that wilforine significantly inhibited the efflux activity of P-gp in a concentration-dependent manner. Further kinetic analysis demonstrated that wilforine significantly inhibited P-gp efflux function by competitive inhibition and stimulated the basal P-gp ATPase activity. In addition, wilforine re-sensitized MDR cancer cells to chemotherapeutic drugs. The docking model indicated that wilforine was bound to residues of P-gp such as LEU884, LYS887, THR176 and ASN172.

CONCLUSION

These results suggest a novel future therapeutic strategy for MDR cancer using wilforine as an adjuvant treatment with chemotherapy.

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.

Multilayer capsules encapsulating nimbin and doxorubicin for cancer chemo-photothermal therapy

Layer-by-layer (LbL) assembled poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMA) microcapsules were designed to incorporate gold nanorods (NRs) and co-encapsulate and release two drugs for cancer therapy. Calcium carbonate (CaCO₃) microparticles modified with preformed NRs were used as sacrificial templates for the fabrication of hollow PAH/PMA/NR capsules incorporated with NRs. The hollow capsules were found to be 4.5 ± 0.5 µm in size and appeared with uniformly distributed NRs in the interior of the capsules. The morphology of the capsules transformed from pore free continuous structure to porous structure under laser light irradiation at 808 nm and 0.5 W cm^-2. The encapsulation experiments showed that the hydrophilic drug (doxorubicin hydrochloride, Dox) was encapsulated in the interior of the capsules while the hydrophobic drug (nimbin, NB) was entrapped in the porous polymeric network of the layer components. The encapsulation efficiency was found to be 30% for both Dox and NB. The release experiments showed an initial burst release followed by sustained release up to 3 h. Notably, the release was completed within 30 min under NIR irradiation at 808 nm. The estimated IC₅₀ values against THP-1 cells were 75 and 1.8 µM for NB and Dox, respectively. The dual drug loaded capsules showed excellent anticancer activity against THP-1 cells under NIR light exposure in in-vitro experiments. Thus, such remotely addressable dual-drug loaded capsules with the provision for encapsulation of natural drugs demonstrate high potential for use as theranostics in cancer therapy.

Research and development of drug delivery systems based on drug transporter and nano-formulation

In recent years, the continuous occurrence of multi-drug resistance in the clinic has made people pay more attention to the transporter. Changes in the expression and activity of transporters can cause corresponding changes in drug pharmacokinetics and pharmacodynamics. The drug-drug interactions (DDI) caused by transporters can seriously affect drug effectiveness and toxicity. In the development of pharmaceutical preparations, people have increasingly concerned about the effects and regulation of transporters in drug effects. To improve the targeting and physicochemical properties of drugs, the development of targeted agents is very rapid. Among them, novel nano-formulations are the best. With the continuous innovation and development of nano-formulation, its application has become more and more extensive. Nano-formulation has exerted certain advantages in the drug development based on transporters, and is also involved in the combination of targeted transporters. This review focuses on the application of novel nano-agents targeting transporters and the introduction of drug-transporter-based nano-formulations.

Improvement of conventional anti-cancer drugs as new tools against multidrug resistant tumors

Multidrug resistance (MDR) is the dominant cause of the failure of cancer chemotherapy. The design of antitumor drugs that are able to evade MDR is rapidly evolving, showing that this area of biomedical research attracts great interest in the scientific community. The current review explores promising recent approaches that have been developed with the aim of circumventing or overcoming MDR. Encouraging results have been obtained in the investigation of the MDR-modulating properties of various classes of natural compounds and their analogues. Inhibition of P-gp or downregulation of its expression have proven to be the main mechanisms by which MDR can be surmounted. The use of hybrid molecules that are able to simultaneously interact with two or more cancer cell targets is currently being explored as a means to circumvent drug resistance. This strategy is based on the design of hybrid compounds that are obtained either by merging the structural features of separate drugs, or by conjugating two drugs or pharmacophores via cleavable/non-cleavable linkers. The approach is highly promising due to the pharmacokinetic and pharmacodynamic advantages that can be achieved over the independent administration of the two individual components. However, it should be stressed that the task of obtaining successful multivalent drugs is a very challenging one. The conjugation of anticancer agents with nitric oxide (NO) donors has recently been developed, creating a particular class of hybrid that can combat tumor drug resistance. Appropriate NO donors have been shown to reverse drug resistance via nitration of ABC transporters and by interfering with a number of metabolic enzymes and signaling pathways. In fact, hybrid compounds that are produced by covalently attaching NO-donors and antitumor drugs have been shown to elicit a synergistic cytotoxic effect in a variety of drug resistant cancer cell lines. Another strategy to circumvent MDR is based on nanocarrier-mediated transport and the controlled release of chemotherapeutic drugs and P-gp inhibitors. Their pharmacokinetics are governed by the nanoparticle or polymer carrier and make use of the enhanced permeation and retention (EPR) effect, which can increase selective delivery to cancer cells. These systems are usually internalized by cancer cells via endocytosis and accumulate in endosomes and lysosomes, thus preventing rapid efflux. Other modalities to combat MDR are described in this review, including the pharmaco-modulation of acridine, which is a well-known scaffold in the development of bioactive compounds, the use of natural compounds as means to reverse MDR, and the conjugation of anticancer drugs with carriers that target specific tumor-cell components. Finally, the outstanding potential of in silico structure-based methods as a means to evaluate the ability of antitumor drugs to interact with drug transporters is also highlighted in this review. Structure-based design methods, which utilize 3D structural data of proteins and their complexes with ligands, are the most effective of the in silico methods available, as they provide a prediction regarding the interaction between transport proteins and their substrates and inhibitors. The recently resolved X-ray structure of human P-gp can help predict the interaction sites of designed compounds, providing insight into their binding mode and directing possible rational modifications to prevent them from becoming P-gp drug substrates. In summary, although major efforts were invested in the search for new tools to combat drug resistant tumors, they all require further implementation and methodological development. Further investigation and progress in the abovementioned strategies will provide significant advances in the rational combat against cancer MDR.

Ginsenoside Rh2 pretreatment and withdrawal reactivated the pentose phosphate pathway to ameliorate intracellular redox disturbance and promoted intratumoral penetration of adriamycin

Improving the limited penetration, accumulation and therapeutic effects of antitumor drugs in the avascular region of the tumor mass is crucial during chemotherapy. P-gp inhibitors have achieved little success despite significant efforts. Excessive P-gp inhibition disturbed the kinetic balance between intracellular accumulation and intercellular penetration, thus resulting in a more inhomogeneous distribution of substrate drugs. Here, we found that ginsenoside Rh2 pretreatment mildly downregulated P-gp expression through reactivating the pentose phosphate pathway and rebalancing redox status. This mild P-gp inhibition not only significantly increased the growth inhibition effect and accumulation profile of adriamycin (ADR) throughout the multicellular tumor spheroid (MCTS) but also had unique advantages in improving drug penetration. Furthermore, we developed a novel individual-cell-based PK-PD integrated model and proved that metabolic reprogramming and redox rebalancing-based P-gp regulation was sufficient to increase the ADR effect in both central and peripheral cells of MCTS. Thus, a “ginsenoside Rh2-ADR” sequential regimen was proposed and exhibited a potent antitumor effect in vivo. This novel P-gp inhibition via metabolic reprogramming and redox rebalancing provided a new idea for achieving better antitumor effects in the tumor avascular region during chemotherapy.

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Rh2 pretreatment downregulated P-gp expression through metabolic reprogramming and redox rebalancing.

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Rh2-pretreatment improved ADR penetration into the core of MCTS and tumour mass.

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“Ginsenoside Rh2-ADR” sequential regimen exhibited potent antitumor effects in vivo.

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.

Overcoming multidrug resistance in cancer: Recent progress in nanotechnology and new horizons

Multidrug resistance (MDR), defined as the ability of cancer cells to gain resistance to both conventional and novel chemotherapy agents, is an important barrier in treating malignancies. Initially, it was discovered that cellular pumps dependent on ATP were the cause of resistance to chemotherapy, and further studies have found that other mechanisms such as increased metabolism of drugs, decreased drug entry, and defective apoptotic pathways are involved in this process. MDR has been the focus of numerous initiatives and countless studies have been undertaken to better understand MDR and formulate strategies to overcome its effects. The current review highlights various nano-drug delivery systems including polymeric/solid lipid/mesoporous silica/metal nanoparticles, dendrimers, liposomes, micelles, and nanostructured lipid carriers to overcome the mechanism of MDR. Nanoparticles are novel gateways to enhance the therapeutic efficacy of anticancer agents at the target site of action due to their tumor-targeting abilities, which can limit the unwanted systemic effects of chemotherapy agents and also reduce drug resistance. Additionally, other innovative strategies including RNA interference as a biological process used to inhibit or silence specific gene expression, natural products as MDR modulators with little systemic toxic effects, which interfere with the functions of proteins involved in drug efflux, and physical approaches such as combination of conventional drug administration with thermal/ultrasound/photodynamic strategies are also highlighted.

Caffeic Acid Attenuates Multi-Drug Resistance in Cancer Cells by Inhibiting Efflux Function of Human P-glycoprotein

: Multidrug resistance (MDR) is a complicated ever-changing problem in cancer treatment, and P-glycoprotein (P-gp), a drug efflux pump, is regarded as the major cause. In the way of developing P-gp inhibitors, natural products such as phenolic acids have gotten a lot of attention recently. The aim of the present study was to investigate the modulating effects and mechanisms of caffeic acid on human P-gp, as well as the attenuating ability on cancer MDR. Calcein-AM, rhodamine123, and doxorubicin were used to analyze the interaction between caffeic acid and P-gp, and the ATPase activity of P-gp was evaluated as well. Resistance reversing effects were revealed by SRB and cell cycle assay. The results indicated that caffeic acid uncompetitively inhibited rhodamine123 efflux and competitively inhibited doxorubicin efflux. In terms of P-gp ATPase activity, caffeic acid exhibited stimulation in both basal and verapamil-stimulated activity. The combination of chemo drugs and caffeic acid resulted in decreased IC₅₀ in ABCB1/Flp-In^TM-293 and KB/VIN, indicating that the resistance was reversed. Results of molecular docking suggested that caffeic acid bound to P-gp through GLU74 and TRY117 residues. The present study demonstrated that caffeic acid is a promising candidate for P-gp inhibition and cancer MDR attenuation.

pH/redox sequentially responsive nanoparticles with size shrinkage properties achieve deep tumor penetration and reversal of multidrug resistance

pH/redox sequentially responsive nanoparticles with size shrinkage properties achieve deep tumor penetration and reversal of multidrug resistance.

A facile metal-free one-pot synthesis of 3-aminoisoquinolines by intramolecular transannulation of 1-sulfonyl-4-(2-aminomethylphenyl)-1,2,3-triazoles

A metal-free one-pot intramolecular transannulation of 1-sulfonyl-4-(2-aminomethylphenyl)-1,2,3-triazoles has been developed, which enables the facile synthesis of the various 3-aminoisoquinolines as well as relevant scaffolds from readily available starting materials.

An efficient method for the construction of 3-aminoisoquinolines through a metal-free one-pot intramolecular transannulation of 1-sulfonyl-4-(2-aminomethylphenyl)-1,2,3-triazoles has been developed.

A modular approach to the bisbenzylisoquinoline alkaloids tetrandrine and isotetrandrine

A modular short-step synthesis of the bisbenzylisoquinoline alkaloids tetrandrine and isotetrandrine was developed employingN-acyl-Pictet–Spengler reaction and Ullman diaryl ether synthesis as central steps.

Oxymatrine reverses 5-fluorouracil resistance by inhibition of colon cancer cell epithelial-mesenchymal transition and NF-κB signaling in vitro

The present study investigated the sensitization of 5-fluorouracil (5-FU)-resistant colon cancer cells in vitro, using oxymatrine, a Chinese herb, and a quinolizidine alkaloid compound extracted from the root of Sophora flavescens. The HCT-8 colon cancer cell line and its 5-FU-resistant subline HCT-8/5-FU were treated with 5-FU and oxymatrine, alone or in combination, at various doses. The cells were subsequently assessed for changes in cell viability, apoptosis and morphology and analyzed by fluorescence microscopy and western blotting. The data demonstrated that HCT-8/5-FU markedly increased the dose of 5-FU required for the suppression of tumor cell viability (78.77±1.90 µg/ml vs. 9.20±0.96 µg/ml in parental HCT-8 cells), whereas HCT-8/5-FU induced the tumor cell epithelial-mesenchymal transition (EMT). By contrast, oxymatrine alone and in combination with 5-FU altered HCT-8/5-FU cell morphology, apoptosis and EMT phenotypes. The combination of oxymatrine and 5-FU reduced the protein expression of snail family transcriptional repressor 2 and vimentin, phosphorylated p65 and induced the expression of E-cadherin, by inhibiting the nuclear factor κB (NF-κB) signaling pathway. In conclusion, the data from the present study demonstrated that EMT was associated with 5-FU chemoresistance in HCT-8/5-FU colon cancer cells, and that oxymatrine treatment was able to reverse such resistance. Oxymatrine may regulate tumor cell EMT and inactivate the NF-κB signaling pathway, and may therefore serve as a potential therapeutic drug to reverse 5-FU resistance in colon cancer cells.

Activity and mechanism of flavokawain A in inhibiting P-glycoprotein expression in paclitaxel resistance of lung cancer

Lung cancer is one of the most common cancers, which is the leading cause of cancer-related death among various cancers worldwide. Flavokawain A (FKA), a chalcone found in the kava plant, exerts potent anticancer activity. However, the activity and mechanisms of FKA in inhibiting the viability of paclitaxel (PTX)-resistant lung cancer A549 (A549/T) have not been investigated. In the present study, the effect of FKA on the viability of A549/T and hepatotoxicity in normal liver epithelial cells was detected by Cell Counting Kit-8 assay. Flow cytometry, western blot analysis and Annexin V-FITC/PI apoptosis detection kit were used to assess cell apoptosis. The effect of FKA on permeability-glycoprotein (P-gp) expression was measured by reverse transcription-PCR and western blot analysis. The results indicated that FKA dose-dependently inhibited cell proliferation and induced cell apoptosis in PTX-resistant A549/T cells, with an IC₅₀ value of ~21 µM, while the IC₅₀ value of A549/T cells to PTX was 34.64 µM. FKA had no hepatic toxicity in liver epithelial cells. P-gp, which contributes to the chemoresistant phenotype, was not expressed in A549 cells but was remarkably enhanced in A549/T cells. FKA (30 µM) decreased P-gp protein expression at 24 h by 3-fold. Furthermore, FKA downregulated P-gp expression by blocking the PI3K/Akt pathway. These findings suggest FKA as a potential candidate for the treatment of PTX-resistant lung cancer.

Antitumor activity of tetrandrine citrate in human glioma U87 cells in vitro and in vivo

Since the current methods of treatment for malignant glioma, radiotherapy and chemotherapy, are unsatisfactory, the development of novel therapeutic compounds is required. In the present study, the inhibitory effect of tetrandrine citrate (TetC) on the proliferation of human glioma U87 cells, as well as its mechanism of action, were investigated. An MTT assay was used to assess cell viability in vitro, and the production of intracellular reactive oxygen species (ROS) was determined by assessing the fluorescence intensity of 2,7-dichlorofluorescein (DCF). Flow cytometry was used to determine the level of apoptosis and cell cycle status, and the protein expression levels of apoptosis-associated proteins were determined using western blotting. Additionally, the antitumor activity of TetC was assessed in vivo using a nude mouse xenograft model. The results revealed that in vitro, the proliferative rate of U87, U251 and human umbilical vein endothelial cells (HUVECs) was significantly reduced in a dose-dependent manner following treatment with TetC, although TetC had the greatest inhibitory effect on U87 cells. The vacuolization and apoptosis of U87 cells was induced using 10 and 20 µmol/l TetC, respectively. The overall proliferative inhibition was associated with an increase in the levels of ROS and apoptosis. In TetC-treated cells, the expression levels of apoptosis-related proteins, including cleaved (CL) caspase-3, Fas, phosphorylated (p)-p38 and p-JNK, were increased, whereas those of caspase-3 and Bcl-2 were decreased. In vivo, TetC was highly effective at inhibiting the growth of human glioma U87 ×enografts in BALB/c nude mice, with a percentage growth inhibition of ≥68.7%. These findings indicated that the potent antitumor activity of TetC may be mediated through an increase in ROS levels, the downregulation of Bcl-2, and the upregulation of CL caspase-3, Fas, p-p38 and p-JNK expression levels.

Toxicity of traditional Chinese medicine herbal and mineral products

Traditional Chinese medicine (TCM) has been used to treat numerous kinds of diseases for more than 2000 years in eastern Asian countries. A portion of the TCM herbal and mineral products are believed to be toxic according to modern standards, and are still widely prescribed in the clinic. However, some TCM products considered to be non-toxic or low-toxic have been reported to possess significant toxicological effects on different organs in both animal and human models. In this review, we define the term "toxic" in TCM, and then we summarize the advances in pharmacology and toxicology research of Toxic Traditional Chinese Medicine (TTCM), including Chinese aconite (Fu Zi), Arsenic Trioxide, Tripterygium wilfordii Hook f. (Thunder God Vine), herbal drugs derived from plants in the Aristolochiaceae Juss. family (Ma Dou Ling), and other TCM products. Finally, the compatibility art of TCM and modern pharmaceutical approaches to manage undesired toxicity of TTCM is discussed. Promoting pharmacology and toxicology studies of TTCM and non-toxic TCM is critical for the further development and safety of TCM in clinical practice.

Constituents and Anti-Multidrug Resistance Activity of Taiwanofungus camphoratus on Human Cervical Cancer Cells

Resistance to anti-cancer drugs is one of the main factors of treatment failure resulting in high morbidity. Among the reasons of resistance, overexpression of efflux pumps leading to multidrug resistance is an important issue that needs to be solved. Taiwanofungus camphoratus has been used as a nutritional supplement to treat various cancers. However, its effects on the resistance to chemotherapeutic agents are still unknown. In this study, we report four new chemical constituents of T. camphoratus isolated from an ether extract: camphoratins K (1) and N (2) and benzocamphorins G (3) and I (4). Furthermore, we evaluated zhankuic acids A–C for their P-glycoprotein (P-gp) inhibitory effects. The results showed that zhankuic acid A was the most potent P-gp inhibitor compound and (at 20 μM) could reverse drug resistance in human cancer cells, restoring an IC₅₀ of 78.5 nM for doxorubicin, of 48.5 nM for paclitaxel, and of 321.5 nM for vincristine, indicating a reversal fold of 48, 38, and 45 times, respectively. This study provides support for the use of T. camphoratus in the further development of cancer therapy.

CA916798 gene expression is associated with multidrug resistance and predicts progression-free survival in patients with lung cancer

CA916798 has been identified as a novel multidrug resistance gene in lung cancer cells. However, the expression patterns of CA916798 in tumor tissues prior and subsequent to chemotherapy remain unclear. In the present study, CA916798 expression levels in tumor tissues prior and subsequent to chemotherapy were detected by reverse transcription-quantitative polymerase chain reaction and immunohistochemistry analysis. The prognostic significance of CA916798 expression in tumor tissues was explored by Kaplan-Meier survival analysis and Cox proportional hazards regression analysis. The messenger RNA (mRNA) and protein expression levels of CA916798 in tumor tissues were downregulated post-chemotherapy in chemotherapy-sensitive patients with lung cancer, but not in chemotherapy-resistant patients. Downregulation of CA916798 mRNA and protein expression post-chemotherapy was significantly associated with improved progression-free survival time. The findings from the present study suggest that platinum-based chemotherapy may induce the expression of CA916798, and CA916798 may be a promising biomarker to predict chemotherapy resistance and improve therapies for patients with lung cancer.

3-benzazecine-based cyclic allene derivatives as highly potent P-glycoprotein inhibitors overcoming doxorubicin multidrug resistance

Aim: Enamino 3-benzazecine compounds, incorporating the C6-C8 allene system, were synthesized and evaluated in vitro as inhibitors of P-glycoprotein (P-gp) and/or multidrug resistance-associated protein 1 (MRP1), two efflux pumps mainly connected with multidrug resistance (MDR) in cancer cells. Results & methodology: Most of the synthesized compounds were selective P-gp inhibitors in Calcein-AM uptake assay. Structure–activity relationships (SARs) pointed out that CO2Me derivatives are more potent than acetyl derivatives, and 10,11-dimethoxy compounds are five to tenfold more potent inhibitors than the respective unsubstituted compounds, and that the P-gp inhibition potency is mainly related to volume parameters. Conclusion: Nanomolar P-gp inhibitors, such as 23 (IC50 = 4.2 nM), restored the antiproliferative activity of doxorubicin in multidrug-resistant cells. The observed activities showed that 3-benzazecine-based compounds may be promising MDR reversers.

CTAB Enhances Chemo-Sensitivity Through Activation of AMPK Signaling Cascades in Breast Cancer

Metabolic reprogramming is thought to be one of the initiators in cancer drug resistance. It has been shown that CTAB is capable of interfering the efficiency of cancer therapy by regulation of cell metabolic reprogramming. In this study, we hypothesized that AMPK as a key metabolic regulator plays a crucial role in regulation of breast cancer drug resistance, which could be alleviated by treatment of CTAB. We observed that CTAB can improve the DOX sensitivity of the breast cancer cells by inhibition of the ATP-dependent drug-efflux pump P-gp complex through activation of the AMPK-HIF-1α-P-gp cascades. The CTAB effect was also confirmed in vivo showing low systemic toxicity. Taken together, our results showed that CTAB sensitized drug resistance of breast cancer to DOX chemotherapy by activating AMPK signaling cascades both in vitro and in vivo, suggested that CTAB may be developed as a promising and novel chemosensitizer and chemotherapeutic candidate for breast cancer treatment.

Similar Safety Profile of the Enantiomeric N-Aminoalkyl Derivatives of Trans-2-Aminocyclohexan-1-ol Demonstrating Anticonvulsant Activity

Epilepsy is one of the most common neurological disorder in the world. Many antiepileptic drugs cause multiple adverse effects. Moreover, multidrug resistance is a serious problem in epilepsy treatment. In the present study we evaluated the safety profile of three (1–3) new chiral N-aminoalkyl derivatives of trans-2-aminocyclohexan-1-ol demonstrating anticonvulsant activity. Our aim was also to determine differences between the enantiomeric compounds with respect to their safety profile. The results of the study indicated that compounds 1–3 are non-cytotoxic for astrocytes, although they exhibit cytotoxic activity against human glioblastoma cells. Moreover, 1–3 did not affect the viability of HepG2 cells and did not produce adducts with glutathione. Compounds 1–3 demonstrated no mutagenic activity either in the Salmonella typhimurium or in Vibrio harveyi tests. Additionally, the compounds displayed a strong or moderate antimutagenic effect. Finally, the P-glycoprotein (P-gp) ATPase assay demonstrated that both enantiomers are potent P-gp inhibitors. To sum up, our results indicate that the newly synthesized derivatives may be considered promising candidates for further research on anticonvulsant drug discovery and development. Our study indicated the similar safety profile of the enantiomeric N-aminoalkyl derivatives of trans-2-aminocyclohexan-1-ol, although in the previous studies both enantiomers differ in their biotransformation pathways and pharmacological activity.

Ivermectin reverses the drug resistance in cancer cells through EGFR/ERK/Akt/NF-κB pathway

Background

Discovery and development of novel drugs that are capable of overcoming drug resistance in tumor cells are urgently needed clinically. In this study, we sought to explore whether ivermectin (IVM), a macrolide antiparasitic agent, could overcome the resistance of cancer cells to the therapeutic drugs.

Methods

We used two solid tumor cell lines (HCT-8 colorectal cancer cells and MCF-7 breast cancer cells) and one hematologic tumor cell line (K562 chronic myeloid leukemia cells), which are resistant to the chemotherapeutic drugs vincristine and adriamycin respectively, and two xenograft mice models, including the solid tumor model in nude mice with the resistant HCT-8 cells and the leukemia model in NOD/SCID mice with the resistant K562 cells to investigate the reversal effect of IVM on the resistance in vitro and in vivo. MTT assay was used to investigate the effect of IVM on cancer cells growth in vitro. Flow cytometry, immunohistochemistry, and immunofluorescence were performed to investigate the reversal effect of IVM in vivo. Western blotting, qPCR, luciferase reporter assay and ChIP assay were used to detect the molecular mechanism of the reversal effect. Octet RED96 system and Co-IP were used to determine the interactions between IVM and EGFR.

Results

Our results indicated that ivermectin at its very low dose, which did not induce obvious cytotoxicity, drastically reversed the resistance of the tumor cells to the chemotherapeutic drugs both in vitro and in vivo. Mechanistically, ivermectin reversed the resistance mainly by reducing the expression of P-glycoprotein (P-gp) via inhibiting the epidermal growth factor receptor (EGFR), not by directly inhibiting P-gp activity. Ivermectin bound with the extracellular domain of EGFR, which inhibited the activation of EGFR and its downstream signaling cascade ERK/Akt/NF-κB. The inhibition of the transcriptional factor NF-κB led to the reduced P-gp transcription.

Conclusions

These findings demonstrated that ivermectin significantly enhanced the anti-cancer efficacy of chemotherapeutic drugs to tumor cells, especially in the drug-resistant cells. Thus, ivermectin, a FDA-approved antiparasitic drug, could potentially be used in combination with chemotherapeutic agents to treat cancers and in particular, the drug-resistant cancers.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1251-7) contains supplementary material, which is available to authorized users.

Influence of concomitant medication on plasma concentration of amiodarone in patients with atrial fibrillation - a pilot study

Background

Although amiodarone is a drug with many side effects, it is one of the most commonly used drugs in the treatment and prophylaxis of supraventricular and ventricular arrhythmias.

Aim

The purpose of this pilot study was to evaluate plasma concentrations of amiodarone in patients with atrial fibrillation (AF) and to identify possible drug-drug interactions between amiodarone and concomitant medications.

Method

A prospective observational study was conducted in 27 consecutive patients treated with amiodarone from May to July 2017 in a Clinical University Hospital. The patients included met our inclusion criteria. HPLC-UV was the device used to determine the plasma concentration of amiodarone.

Results

Only 51.8% of the patients had amiodarone plasma concentration within therapeutic interval (500–2500 ng/ml). The drugs associated to amiodarone in the therapeutic plan were diuretics, beta blockers, statins, antiplatelets, fluoroquinolones, non-steroidal anti-inflammatory drugs. We observed a statistically significant difference between the plasmatic concentrations of amiodarone in patients treated with furosemide vs. patients concomitantly treated with other drugs. Interactions between other mentioned drugs and amiodarone were not registered. We can report an underuse of amiodarone for more than 50% of the patients. Also, we found a significant interaction between furosemide and amiodarone, most likely through the interaction with MDR.

Conclusion

Furosemide may influence the pharmacokinetics of P-gp-interfering drugs. However, the relevance of these findings needs to be confirmed and further research is needed to characterize the interaction between amiodarone and furosemide.

Controlling metastatic cancer: the role of phytochemicals in cell signaling

PURPOSE

Cancer is a serious health issue and a leading cause of death worldwide. Most of the cancer patients (approximately 90%) do not die from the consequences of the primary tumor development, but due to a heavily treatable metastatic invasion. During the lengthy multistep process of carcinogenesis, there are a lot of opportunities available to reverse or slow down the tissue invasion or the process of tumor metastasis formation.

RESULTS

Current research has brought many promising results from anti-metastatic experimental studies, and has shown that chemoprevention by natural or semisynthetic phytochemicals with plethora of biological activities could be one of the potentially effective options in the fight against this problem. However, there is a lack of clinical trials to confirm these findings. In this review, we focused on summarization and discussion of the general features of metastatic cancer, and recent preclinical and clinical studies dealing with anti-metastatic potential of various plant-derived compounds.

CONCLUSIONS

Based on our findings, we can conclude and confirm our hypothesis that phytochemicals with pleiotropic anticancer effects can be very useful in retarding and/or reversing the metastasis process, and can also be used to prevent tissue invasion and metastases. But, further studies in this area are certainly necessary and desirable.