18F-Labeled dihydropyridines via Hantzsch reaction for positron emission tomography of P-glycoprotein dysfunction.

Despite the availability of various 11C-labeled positron emission tomography (PET) tracers for assessing P-glycoprotein (P-gp) function, there are still limitations related to complex metabolism, high lipophilicity, and low baseline uptake. This study aimed to address these issues by exploring a series of customized dihydropyridines (DHPs) with enhanced stability and reduced lipophilicity as alternative PET tracers for P-gp dysfunction. Compared with verapamil and the rest DHPs, dimethyl 4-(4-fluorophenyl)-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate (1) exhibited superior cellular uptake differences between the human gastric cancer cell line SGC7901 and its drug-resistant counterpart. [18F]1 is successfully synthesized using a novel "hot-Hantzsch" approach in 22.1 ± 0.1 % radiochemical yields. MicroPET/CT imaging demonstrated that the uptake of [18F]1 in the brains of P-gp blocked mice increased by > 3 times compared to the control group. Additionally, [18F]1 displayed favorable lipophilicity (log D = 2.3) and excellent clearance characteristics, making it a promising tracer candidate with low background noise and high contrast.

BI-2865, a pan-KRAS inhibitor, reverses the P-glycoprotein induced multidrug resistance in vitro and in vivo.

BACKGROUND: Multidrug resistance (MDR) limits successful cancer chemotherapy. P-glycoprotein (P-gp), BCRP and MRP1 are the key triggers of MDR. Unfortunately, no MDR modulator was approved by FDA to date. Here, we will investigate the effect of BI-2865, a pan-KRAS inhibitor, on reversing MDR induced by P-gp, BCRP and MRP1 in vitro and in vivo, and its reversal mechanisms will be explored. METHODS: The cytotoxicity of BI-2865 and its MDR removal effect in vitro were tested by MTT assays, and the corresponding reversal function in vivo was assessed through the P-gp mediated KBv200 xenografts in mice. BI-2865 induced alterations of drug discharge and reservation in cells were estimated by experiments of Flow cytometry with fluorescent doxorubicin, and the chemo-drug accumulation in xenografts' tumor were analyzed through LC-MS. Mechanisms of BI-2865 inhibiting P-gp substrate's efflux were analyzed through the vanadate-sensitive ATPase assay, [125I]-IAAP-photolabeling assay and computer molecular docking. The effects of BI-2865 on P-gp expression and KRAS-downstream signaling were detected via Western blotting, Flow cytometry and/or qRT-PCR. Subcellular localization of P-gp was visualized by Immunofluorescence. RESULTS: We found BI-2865 notably fortified response of P-gp-driven MDR cancer cells to the administration of chemo-drugs including paclitaxel, vincristine and doxorubicin, while such an effect was not observed in their parental sensitive cells and BCRP or MRP1-driven MDR cells. Importantly, the mice vivo combination study has verified that BI-2865 effectively improved the anti-tumor action of paclitaxel without toxic injury. In mechanism, BI-2865 prompted doxorubicin accumulating in carcinoma cells by directly blocking the efflux function of P-gp, which more specifically, was achieved by BI-2865 competitively binding to the drug-binding sites of P-gp. What's more, at the effective MDR reversal concentrations, BI-2865 neither varied the expression and location of P-gp nor reduced its downstream AKT or ERK1/2 signaling activity. CONCLUSIONS: This study uncovered a new application of BI-2865 as a MDR modulator, which might be used to effectively, safely and specifically improve chemotherapeutic efficacy in the clinical P-gp mediated MDR refractory cancers.

Discovery of oral chemotherapeutic reversal agents for treating multidrug resistance cancer.

The major limitation of cancer treatment is multidrug resistance (MDR), which leads to the inactivation of chemotherapeutic drugs and greater than 90% mortality. To solve this ordeal, we applied ligand-based drug design and bioiosteric replacement strategy from an indazole to a pyrazole ring to discover compounds 27 and 43 with good potential for reversing drug resistance in combination with paclitaxel, and their reversal fold values were 53.2 and 51.0 at 5 µM, respectively, against an MDR cancer cell line (KBvin). Based on the PK profile results, we selected compound 43 with a longer half-life for mechanistic and animal experiments. Combination treatment with compound 43 and paclitaxel-induced apoptosis and enhanced subG1 by decreasing mitochondrial membrane potential in KBvin cells. In addition, 43 also inhibited P-gp function by interfering with ATPase activity. Meanwhile, cotreatment with compound 43 and paclitaxel significantly suppressed tumor growth (TGI = 55.5%) at a dose of 200 mg/kg (PO) in a xenograft model and showed no obvious liver or kidney toxicity by H&E staining. Overall, compound 43 may serve as a safe and effective oral resistance reversal chemotherapeutic agent.

Design, synthesis, molecular modeling, in vitro and in vivo biological evaluation of potent anthranilamide derivatives as dual P-glycoprotein and CYP3A4 inhibitors.

Paclitaxel (PTX) is considered the blockbuster chemotherapy treatment for cancer. Paclitaxel's (PTX) oral administration has proven to be extremely difficult, mostly because of its susceptibility to intestinal P-glycoprotein (P-gp) and cytochrome P450 (CYP3A4). The concurrent local inhibition of intestinal P-gp and CYP3A4 is a promising approach to improve the oral bioavailability of paclitaxel while avoiding potential unfavorable side effects of their systemic inhibition. Herein, we report the rational design and evaluation of novel dual potent inhibitors of P-gp and CYP3A4 using an anthranilamide derivative tariquidar as a starting point for their structural optimizations. Compound 14f, bearing N-imidazolylbenzyl side chain, was found to have potent and selective P-gp (EC50 = 28 nM) and CYP3A4 (IC50 = 223 nM) inhibitory activities with low absorption potential (Papp (A-to-B) <0.06). In vivo, inhibitor 14f improved the oral absorption of paclitaxel by 6 times in mice and by 30 times in rats as compared to vehicle, while 14f itself remained poorly absorbed. Compound 14f, possessing dual P-gp and CYP3A4 inhibitory activities, offered additional enhancement in paclitaxel oral absorption compared to tariquidar in mice. Evaluating the CYP effect of 14f on oral absorption of paclitaxel requires considering the variations in CYP expression between animal species. This study provides further medicinal chemistry advice on strategies for resolving concerns with the oral administration of chemotherapeutic agents.

Tolerability of tariquidar - A third generation P-gp inhibitor as add-on medication to antiseizure medications in drug-resistant epilepsy.

PURPOSE: P-glycoprotein (P-gp) has been hypothesized to be involved in drug-resistance of epilepsy by actively extruding antiseizure medications (ASMs) from the brain. The P-gp inhibitor tariquidar (TQD) has been shown to effectively inhibit P-gp at the human blood-brain barrier, improving brain entry of several ASMs. A potential strategy to overcome drug-resistance is the co-administration of P-gp inhibitors such as TQD to ASMs. Here we present data on the tolerability of single-dose TQD as a potential add-on medication to ASMs. METHODS: We performed a multi-centre cohort study including drug-resistant epilepsy patients and healthy controls from the United Kingdom and Austria. TQD was administered intravenously at five different doses (2 mg/kg or 3 mg/kg of TQD were given to drug-resistant epilepsy patients and healthy controls, higher doses of TQD at 4 mg/kg, 6 mg/kg and 8 mg/kg as well as a prolonged infusion aiming at a dose of 6 mg/kg were only given to healthy controls). Adverse events were recorded and graded using the Common Terminology Criteria (CTCAE) scale. Additionally, TQD plasma concentration levels were measured and compared between drug-resistant patients and healthy controls. RESULTS: In total, 108 participants received TQD once at variable doses and it was overall well tolerated. At doses of 2 or 3 mg/kg TQD, only two of the 19 drug-resistant epilepsy patients and a third of the healthy controls (n = 14/42) reported adverse events probably related to TQD. The majority of those adverse events (96 %) were reported as mild. One drug-resistant epilepsy patient reported adverse events 24-hours after TQD administration possibly related to TQD-induced increased ASMs levels in the brain. CONCLUSIONS: TQD is an effective and well tolerated P-gp inhibitor as a single dose and could potentially be used intermittently in conjunction with ASMs to improve efficacy. This promising strategy to overcome drug-resistance in epilepsy should be investigated further in clinical randomised controlled trials.

P-gp inhibition and enhanced oral bioavailability of amikacin Sulfate: A novel approach using Thiolated Chito-PEGylated Lipidic Hybrids.

This study aimed to develop oral lipidic hybrids of amikacin sulfate (AMK), incorporating thiolated chitosan as a P-glycoprotein (P-gp) inhibitor to enhance intestinal absorptivity and bioavailability. Three formulations were designed: PEGylated Liposomes, Chitosan-functionalized PEGylated (Chito-PEGylated) Lipidic Hybrids, and Thiolated Chito-PEGylated Lipidic Hybrids. The physical characteristics of nanovesicles were assessed. Ex-vivo permeation and confocal laser scanning microscopy (CLSM) studies were conducted to evaluate the formulations' potential to enhance AMK intestinal permeability. In-vivo pharmacokinetic studies in rats and histological/biochemical investigations assessed the safety profile and oral bioavailability. The AMK-loaded Thiolated Chito-PEGylated Lipidic Hybrids exhibited favorable physical characteristics, higher ex-vivo permeation parameters, and verified P-gp inhibition via CLSM. They demonstrated heightened oral bioavailability (68.62% absolute bioavailability) and a sufficient safety profile. Relative bioavailability was significantly higher (1556.3% and 448.79%) compared to PEGylated Liposomes and Chito-PEGylated Lipidic Hybrids, respectively, indicating remarkable oral AMK delivery with fewer doses, reduced side effects, and enhanced patient compliance.

α-Fluorination of tropane compounds and its impact on physicochemical and ADME properties.

Using an electrochemical C(sp3)-H fluorination reaction, a series of α-fluorinated tropane compounds were synthesized and their druglikeness parameters were assessed to compare with the parent compounds. Improvements were observed in membrane permeability, P-gp liability, and inhibitory effects on hERG and Nav1.5 channels, accompanied with a trend of decreased aqueous solubility and microsomal stability. It was also revealed that α-fluorination reduced the basicity of tropane nitrogen atom for about 1000-fold.

Impact of P-gp inhibition on systemic exposure of pralsetinib and dosing considerations.

A study to determine the impact of cyclosporine (Neoral), an inhibitor of P-gp, on the pharmacokinetics of pralsetinib (trade name GAVRETO®) was conducted in 15 healthy adult volunteers. A single 200 mg dose of pralsetinib was administered orally alone and in combination with cyclosporine with a 9-day washout between treatments. Co-administration with cyclosporine resulted in a clinically relevant increase in pralsetinib maximum plasma concentration (Cmax) and area under the plasma concentration-time curve extrapolated to infinity (AUC0-∞) with associated geometric mean ratios (GMRs) and 90% confidence intervals (CIs) of 148% (109, 201) and 181% (136, 241), respectively. These findings provide insight into concomitant dosing of pralsetinib with inhibitors of P-gp given the increases in pralsetinib exposure observed when administered with cyclosporine. Based on these results, co-administration of pralsetinib with P-gp inhibitors is not recommended. In the event that co-administration cannot be avoided, it is recommended that the dose of pralsetinib be reduced.

Novel pyxinol amide derivatives bearing an aliphatic heterocycle as P-glycoprotein modulators for overcoming multidrug resistance.

P-glycoprotein (Pgp) modulators are promising agents for overcoming multidrug resistance (MDR) in cancer chemotherapy. In this study, via structural optimization of our lead compound S54 (nonsubstrate allosteric inhibitor of Pgp), 29 novel pyxinol amide derivatives bearing an aliphatic heterocycle were designed, synthesized, and screened for MDR reversal activity in KBV cells. Unlike S54, these active derivatives were shown to transport substrates of Pgp. The most potent derivative 4c exhibited promising MDR reversal activity (IC50 of paclitaxel = 8.80 ± 0.56 nM, reversal fold = 211.8), which was slightly better than that of third-generation Pgp modulator tariquidar (IC50 of paclitaxel = 9.02 ± 0.35 nM, reversal fold = 206.6). Moreover, the cytotoxicity of this derivative was 8-fold lower than that of tariquidar in human normal HK-2 cells. Furthermore, 4c blocked the efflux function of Pgp and displayed high selectivity for Pgp but had no effect on its expression and distribution. Molecular docking revealed that 4c bound preferentially to the drug-binding domain of Pgp. Overall, 4c is a promising lead compound for developing Pgp modulators.

Polyvinylpyrrolidone Assisted One-Pot Synthesis of Size-Tunable Cocktail Nanodrug for Multifunctional Combat of Cancer.

Background: The in vivo barriers and multidrug resistance (MDR) are well recognized as great challenges for the fulfillment of antitumor effects of current drugs, which calls for the development of novel therapeutic agents and innovative drug delivery strategies. Nanodrug (ND) combining multiple drugs with distinct modes of action holes the potential to circumvent these challenges, while the introduction of photothermal therapy (PTT) can give further significantly enhanced efficacy in cancer therapy. However, facile preparation of ND which contains dual drugs and photothermal capability with effective cancer treatment ability has rarely been reported. Methods: In this study, we selected curcumin (Cur) and doxorubicin (Dox) as two model drugs for the creation of a cocktail ND (Cur-Dox ND). We utilized polyvinylpyrrolidone (PVP) as a stabilizer and regulator to prepare Cur-Dox ND in a straightforward one-pot method. Results: The size of the resulting Cur-Dox ND can be easily adjusted by tuning the charged ratios. It was noted that both loaded drugs in Cur-Dox ND can realize their functions in the same target cell. Especially, the P-glycoprotein inhibition effect of Cur can synergistically cooperate with Dox, leading to enhanced inhibition of 4T1 cancer cells. Furthermore, Cur-Dox ND exhibited pH-responsive dissociation of loaded drugs and a robust photothermal translation capacity to realize multifunctional combat of cancer for photothermal enhanced anticancer performance. We further demonstrated that this effect can also be realized in 3D multicellular model, which possibly attributed to its superior drug penetration as well as photothermal-enhanced cellular uptake and drug release. Conclusion: In summary, Cur-Dox ND might be a promising ND for better cancer therapy.

Digestion of surfactants does not affect their ability to inhibit P-gp-mediated transport in vitro.

While various non-ionic surfactants at low concentrations have been shown to increase the transport of P-gp substrates in vitro, in vivo studies in rats have shown that a higher surfactant concentration is needed to increase the oral absorption of e.g. the P-gp substrates digoxin and etoposide. The aim of the present study was to investigate if intestinal digestion of surfactants could be the reason for this deviation between in vitro and in vivo data. Therefore, Kolliphor EL, Brij-L23, Labrasol and polysorbate 20 were investigated for their ability to inhibit P-gp and increase digoxin absorption in vitro. Transport studies were performed in Caco-2 cells, while P-gp inhibition and cell viability assays were performed in MDCKII-MDR1 cells. Polysorbate 20, Kolliphor EL and Brij-L23 increased absorptive transport and decreased secretory digoxin transport in Caco-2 cells, whereas only polysorbate 20 and Brij-L23 showed P-gp inhibiting properties in the MDCKII-MDR1 cells. Polysorbate 20 and Brij-L23 were chosen for in vitro digestion prior to transport- or P-gp inhibiting assays. Brij-L23 was not digestible, whereas polysorbate 20 reached a degree of digestion around 40%. Neither of the two surfactants showed any significant difference in their ability to affect absorptive or secretory transport of digoxin after pre-digestion. Furthermore, the P-gp inhibiting effects of polysorbate 20 were not decreased significantly. In conclusion, the mechanism behind the non-ionic surfactant mediated in vitro P-gp inhibition seemed independent of the intestinal digestion and the results presented here did not suggest it to be the cause of the observed discrepancy between in vitro and in vivo.

Effectiveness and Safety of Different Oral Anticoagulants with P-glycoprotein/ CYP3A4 Inhibitors: A Network Meta-analysis.

BACKGROUND: Metabolism of oral anticoagulants (OAC) is affected by P-glycoprotein (P-gp)/ CYP3A4 enzyme. However, the P-gp/CYP3A4 inhibitors are unavoidably used with OACs. METHODS: Medline, Cochrane, and Embase were systematically searched for randomized controlled trials and cohort studies from inception till 23rd November, 2022 to assess the safety and effectiveness of OACs when concomitantly used with P-gp/CYP3A4 inhibitors. The primary outcomes were major bleeding and gastrointestinal (GI) bleeding. Secondary outcomes were stroke/systemic embolism (SE), all-cause mortality, any bleeding as well as intracranial hemorrhage (ICH). We estimated summary odds ratios (OR) with 95% credible intervals (CI) using pairwise and network meta-analysis with random effects. RESULTS: A total of 11 studies involving 37,973 patients were included. When concomitantly used with P-pg/ CYP3A4 inhibitors, network meta-analysis indicated that dabigatran, apixaban, and edoxaban were associated with significantly lower risk of major bleeding compared to rivaroxaban, with ORs of 0.56, 0.51 and 0.48, respectively. Rivaroxaban and dabigatran were associated with a significantly increased risk of GI bleeding than warfarin, apixaban and edoxaban. Dabigatran and apixaban were linked with significantly lower risk of any bleeding compared with warfarin (ORs were 0.75 and 0.68, respectively) or rivaroxaban (ORs were 0.67 and 0.60, respectively). Apixaban (OR 0.32) and edoxaban (OR 0.35) were associated with a lower risk of ICH compared with warfarin. There was no difference between any OACs in terms of stroke/SE or all-cause mortality. CONCLUSION: When concomitantly used with P-gp/CYP3A4 inhibitors, apixaban and edoxaban were associated with a lower risk of bleeding, though no significant difference in effectiveness was observed among all OACs.

Do P-glycoprotein Medications Alter the Risk of Ventriculoperitoneal Shunt in Adults with Hydrocephalus?

Hydrocephalus is a disorder caused by excess fluid accumulation in the brain and results in brain damage with consequent cognitive and physical problems. This condition has no cure; the only treatment is brain surgery. Experimental data indicate that P-glycoprotein (P-gp) plays a crucial role in the pathogenesis of hydrocephalus due to its function in clearing macromolecules from the brain. Numerous medications frequently used are classified as P-gp inducers or inhibitors, and comprehending their effects may aid in attaining improved patient outcomes. Therefore, in this single-center retrospective study, we examined the risk of the need for ventriculoperitoneal shunt placement over 10 years among 4588 adult patients with hydrocephalus not exposed to any P-gp inhibitors/inducers or exclusively exposed to either P-gp inhibitors or inducers. Our analysis shows that patients exposed to P-gp inhibitors had a 3.2 times higher risk of requiring ventriculoperitoneal shunt surgery (P < .0001). In contrast, the relative risk was not significantly affected (P = .07) among those exposed to P-gp inducers. Our findings indicate the need for caution when prescribing P-gp inhibitors to patients with hydrocephalus. Additional studies using larger cohorts are required to confirm whether P-gp inducers in patients with hydrocephalus can mitigate the risk of ventriculoperitoneal shunt.

Low-dose Pimecrolimus, an FDA-approved Calcineurin Inhibitor, Sensitizes Drug-resistant Cancer Cells via Strong P-gp Inhibition.

BACKGROUND/AIM: Co-treatment with calcineurin inhibitors, such as tacrolimus and cyclosporin A, can sensitize chemotherapy-resistant cancer cells with P-glycoprotein (P-gp)-over-expression. Pimecrolimus (PIME) is a clinically available calcineurin inhibitor with a structure similar to that of tacrolimus. Whether PIME can sensitize P-gp-over-expressing resistant cancer cells remains unclear. MATERIALS AND METHODS: Cell viability assay, annexin V analyses, cellular morphology and density observation with a microscope, western-blotting, fluorescence-activated cell sorting (FACS), and analysis for P-gp inhibitory activity were performed to investigate the mechanism of action. RESULTS: PIME exhibited strong cytotoxicity to vincristine (VIC)-treated drug-resistant cell lines (KBV20C and MCF-7/ADR) over-expressing P-gp. Co-treatment with VIC and PIME increased apoptosis and down-regulated the ERK signaling pathway, resulting in G2 arrest. PIME could be co-administered with vinorelbine or eribulin to sensitize resistant KBV20C or MCF-7/ADR cancer cells. Moreover, PIME strongly inhibited the efflux of both rhodamine 123 and calcein-AM substrates through P-gp after 4 h of treatment, indicating that VIC+PIME sensitized cancer cells by inhibiting VIC efflux via direct PIME binding to P-gp. Low doses of PIME, tacrolimus, and cyclosporin A showed similar sensitizing efficiencies in resistant KBV20C cells. These drugs showed similar P-gp inhibitory activities using both rhodamine 123 and calcein-AM substrates, suggesting that calcineurin inhibitors generally have strong P-gp inhibitory activities that sensitize drug-resistant cancer cells with P-gp over-expression. CONCLUSION: PIME, currently used in clinics, can be repositioned for treating patients with P-gp-over-expressing resistant cancer (stem) cells.

Natural Inhibitors of P-glycoprotein in Acute Myeloid Leukemia.

Acute myeloid leukemia (AML) remains an insidious neoplasm due to the percentage of patients who develop resistance to both classic chemotherapy and emerging drugs. Multidrug resistance (MDR) is a complex process determined by multiple mechanisms, and it is often caused by the overexpression of efflux pumps, the most important of which is P-glycoprotein (P-gp). This mini-review aims to examine the advantages of using natural substances as P-gp inhibitors, focusing on four molecules: phytol, curcumin, lupeol, and heptacosane, and their mechanism of action in AML.

Statins Increase the Bioavailability of Fixed-Dose Combination of Sofosbuvir/Ledipasvir by Inhibition of P-glycoprotein.

BACKGROUND: Coadministration of statins and direct acting antiviral agents is frequently used. This study explored the effects of both atorvastatin and lovastatin on pharmacokinetics of a fixed-dose combination of sofosbuvir/ledipasvir "FDCSL". METHODS: 12 healthy volunteers participated in a randomized, three-phase crossover trial and were administered a single atorvastatin dose 80 mg plus tablet containing 400/90 mg FDCSL, a single lovastatin dose 40 mg plus tablet containing 400/90 mg FDCSL, or tablets containing 400/90 mg FDCSL alone. Liquid chromatography-tandem mass spectrometry was used to analyze plasma samples of sofosbuvir, ledipasvir and sofosbuvir metabolite "GS-331007" and their pharmacokinetic parameters were determined. RESULTS: Atorvastatin caused a significant rise in sofosbuvir bioavailability as explained by increasing in AUC0-∞ and Cmax by 34.36% and 11.97%, respectively. In addition, AUC0-∞ and Cmax of GS-331007 were increased by 73.73% and 67.86%, respectively after atorvastatin intake. Similarly, co-administration of lovastatin with FDCSL increased the bioavailability of sofosbuvir, its metabolite (AUC0-∞ increase by 17.2%, 17.38%, respectively, and Cmax increase by 12.03%, 22.24%, respectively). However, neither atorvastatin nor lovastatin showed a change in ledipasvir bioavailability. Hepatic elimination was not affected after statin intake with FDCSL. Compared to lovastatin, atorvastatin showed significant increase in AUC0-∞ and Cmax of both sofosbuvir and its metabolite. CONCLUSIONS: Both atorvastatin and lovastatin increased AUC of sofosbuvir and its metabolite after concurrent administration with FDCSL. Statins' P-glycoprotein inhibition is the attributed mechanism of interaction. The increase in sofosbuvir bioavailability was more pronounced after atorvastatin intake. Close monitoring is needed after co-administration of atorvastatin and FDCSL.

JAK2 Inhibitor, Fedratinib, Inhibits P-gp Activity and Co-Treatment Induces Cytotoxicity in Antimitotic Drug-Treated P-gp Overexpressing Resistant KBV20C Cancer Cells.

P-glycoprotein (P-gp) overexpression is one of the major mechanisms of multidrug resistance (MDR). Previously, co-treatment with Janus kinase 2 (JAK2) inhibitors sensitized P-gp-overexpressing drug-resistant cancer cells. In this study, we assessed the cytotoxic effects of JAK2 inhibitor, fedratinib, on drug-resistant KBV20C cancer cells. We found that co-treatment with fedratinib at low doses induced cytotoxicity in KBV20C cells treated with vincristine (VIC). However, fedratinib-induced cytotoxicity was little effect on VIC-treated sensitive KB parent cells, suggesting that these effects are specific to resistant cancer cells. Fluorescence-activated cell sorting (FACS), Western blotting, and annexin V analyses were used to further investigate fedratinib's mechanism of action in VIC-treated KBV20C cells. We found that fedratinib reduced cell viability, increased G2 arrest, and upregulated apoptosis when used as a co-treatment with VIC. G2 phase arrest and apoptosis in VIC-fedratinib-co-treated cells resulted from the upregulation of p21 and the DNA damaging marker pH2AX. Compared with dimethyl sulfoxide (DMSO)-treated cells, fedratinib-treated KBV20C cells showed two-fold higher P-gp-inhibitory activity, indicating that VIC-fedratinib sensitization is dependent on the activity of fedratinib. Similar to VIC, fedratinib co-treatment with other antimitotic drugs (i.e., eribulin, vinorelbine, and vinblastine) showed increased cytotoxicity in KBV20C cells. Furthermore, VIC-fedratinib had similar cytotoxic effects to co-treatment with other JAK2 inhibitors (i.e., VIC-CEP-33779 or VIC-NVP-BSK805) at the same dose; similar cytotoxic mechanisms (i.e., early apoptosis) were observed between treatments, suggesting that co-treatment with JAK2 inhibitors is generally cytotoxic to P-gp-overexpressing resistant cancer cells. Given that fedratinib is FDA-approved, our findings support its application in the co-treatment of P-gp-overexpressing cancer patients showing MDR.

Nanocarrier-based co-delivery approaches of chemotherapeutics with natural P-glycoprotein inhibitors in the improvement of multidrug resistance cancer therapy.

Chemotherapy is the mainstay in cancer treatment; however, its application is clinically limited to patients with multidrug resistance (MDR). MDR reverses the role of chemotherapy through significant attribution to pharmacokinetic characteristics, where ATP-binding cassette transporter proteins, P-glycoprotein (P-gp), pump out the intracellularly transported chemotherapeutics from the cancer cells. Therefore, overexpression of such receptors on MDR cancer cell surfaces tends to decrease the efficacy of a large number of existing chemotherapeutics. P-gp inhibitors, especially of natural origin, play a vital role in enhancing the cellular concentration of clinically applicable chemotherapeutics. Therefore, co-administration of these natural P-gp inhibitors with chemotherapeutics could improve chemotherapeutic efficacy against MDR cancer, which has been evidenced in the literature. Co-delivery of these therapeutic components can effectively be made using the emerging nanotechnology platform, which could facilitate controlled delivery of the incorporated components to the cancerous microenvironment, through passive and active targeting. Thereby, cellular retention of chemotherapeutic agents by the P-gp mediated inhibitory effect on the efflux pump using the nanocarrier co-delivery platform could improve the anticancer potential of the chemotherapeutics. This review has presented the advancement of naturally occurring P-gp inhibitors as a promising adjuvant in chemotherapy to modulate the pharmacokinetic properties of chemotherapeutic agents using the nanotechnology platform.

Carvacrol Enhance Apoptotic Effect of 5-FU on MCF-7 Cell Line via inhibiting P-glycoprotein: An In-silco and In-vitro Study.

BACKGROUND: P-glycoprotein (P-gp), is an ATP-dependent efflux transporter and overexpressed in cancer cells which is responsible for drug resistance and transportation of anticancer agents out of cells. Hence, P-gp inhibition is a promising way to reverse multi-drug resistance, finding a suitable inhibitor is essential. Carvacrol, an active compound of thyme, has been shown anticancer properties in several types of cancers but the mechanisms underlying this effect remain unclear. Here, we evaluated the inhibitory effects of carvacrol on P-gp by In-silco and in-vitro studies. METHOD: carvacrol was docked against P-gp via autodock vina software to identify the potential binding of this agent. Verapamil, a well-known P-gp inhibitor, was selected as the control ligands. Cell proliferation and apoptosis were assessed using MTT assay and ELISA cell death assay, respectively. RESULTS: It was observed that carvacrol exhibited appropriate affinity (-7 kcal/mol) to drug binding pocket of P-gp when compared with verapamil that showed binding affinities of -8 kcal/mol. The result of MTT assay showed a dose-dependent inhibitory effect of carvacrol and 5-FU. Data of apoptosis assay showed that combining carvacrol with 5-FU increased apoptotic effect of 5-FU 6.7-Fold rather than the control group. This ability to enhance apoptosis is more than the combination of verapamil and 5-FU (4.26-Fold). CONCLUSION: These results provide important evidence that carvacrol may be a promising agent able to overcome P-gp-mediated MDR.

Neochrysosporazines: Precursor-Directed Biosynthesis Defines a Marine-Derived Fungal Natural Product P-Glycoprotein Inhibitory Pharmacophore.

Upregulation of ATP binding cassette (ABC) transporter efflux pumps (i.e. P-glycoprotein, P-gp) can impart multidrug resistance, rendering many chemotherapeutics ineffective and seriously limiting treatment regimes. While ABC transporters remain an attractive target for therapeutic intervention, the development of clinically useful small-molecule inhibitors has proved challenging. In this report, we describe the structure-activity relationship (SAR) analysis of a newly discovered P-gp inhibitory pharmacophore, phenylpropanoid piperazine chrysosporazines, produced by co-isolated marine-derived fungi. In the absence of any total syntheses, we apply an innovative precursor-directed biosynthesis strategy that successfully repurposed fungal biosynthetic output, allowing us to isolate, characterize, and identify the structurally diverse neochrysosporazines A-Q. SAR analysis utilizing all known (and new) neochrysosporazines, chrysosporazines, and azachrysosporazines, plus semi-synthetic analogues, established the key structure requirements for the P-gp inhibitory pharmacophore, and, in addition, identified non-essential sites that allow for the design of affinity and other conjugated probes.