HZ08, a great regulator to reverse multidrug resistance via cycle arrest and apoptosis sensitization in MCF-7/ADM

HZ08 suppresses RelB-activated MnSOD expression and enhances Radiosensitivity of prostate Cancer cells

Background

The development of radioresistance is one of main causes for therapeutic failure of prostate cancer (PCa). The present study aims to investigate the function and the related mechanism by which HZ08 sensitizes radiotherapeutic efficiency to treat aggressive PCa cells.

Methods

PCa cells were pretreated with HZ08 (6,7-dimethoxy-1-(3,4-dimethoxy) benzyl-2-(N-n-octyl-N′-cyano) guanyl-1,2,3,4-tetrahydroisoquinoline) and followed by ionizing radiation (IR) treatment. Cytotoxicity in the treated cells was analyzed to assess the radiosensitization capacity of HZ08 by flow cytometry, MTT and colony survival assays. The cellular levels of reactive oxygen species (ROS) and oxygen consumption rates (OCR) were measured using specific ROS detection probes and a Seahorse XF96 Analyzer, respectively. RelB binding to the NF-κB intronic enhancer region of the human SOD2 gene was determined using a ChIP assay. The levels of phosphorylation of PI3K, Akt and IKKα were quantified and further confirmed using a PI3K inhibitor. Finally, the synergistic effect of HZ08 on radiosensitization of PCa cells was validated using a mouse xenograft tumor model.

Results

HZ08 enhanced radiosensitivity of PCa cells through increasing ROS and declining mitochondrial respiration due to suppression of mitochondrial antioxidant enzyme MnSOD. Mechanistically, HZ08 appeared to inhibit PI3K/Akt/IKKα signaling axis, resulting in transcriptional repression of MnSOD expression by preventing RelB nuclear translocation.

Conclusions

HZ08 can serve as a useful radiosensitizing agent to improve radiotherapy for treating aggressive PCa cells with high level of constitutive RelB. The present study suggests a promising approach for enhancing radiotherapeutic efficiency to treat advanced PCa by inhibiting antioxidant defense function.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0849-5) contains supplementary material, which is available to authorized users.

Triterpenoids from Aglaia abbreviata exert cytotoxicity and multidrug resistant reversal effect in MCF-7/ADM cells via reactive oxygen species induction and P-glycoprotein inhibition

Triterpenoids from the Aglaia have been shown cytotoxicity on a broad spectrum of human tumor cells. In the present study, we extracted triterpenoids AA-5 (1) and AA-6 (2) from stems of Aglaia abbreviata, and studied their cytotoxicity in multidrug resistant (MDR) MCF-7/ADM cells. After 48 h treatment, AA-5 (1) and AA-6 (2) significantly increased mitochondrial-mediated apoptosis by enhancing reactive oxygen species (ROS) with depressed mitochondrial membrane potential and caspase-9 activities. The drug efflux transporter P-glycoprotein (P-gp) and the intracellular antioxidant systems, involving Glutathione S-Transferase π, Glutathione and heme oxygenase-1, were also inhibited via the ROS-depressed Akt/NF-E2-related factor 2 pathway. Furthermore, 2 h-treatment of AA-6 (2) at non-toxic concentrations exhibited MDR reversal effects with no alteration on P-gp expression but increased drug accumulation ability. AA-6 alos demonstrated synergetic effects with classic anti-tumor agents. Moreover, computational modeling studies showed that AA-6 (2) might bind to the modulator site on P-gp and act as an inhibitor, not a substrate of P-gp. Therefore, AA-5 (1) and AA-6 (2) may be effective anti-tumor and reversal agents for the further development of therapeutics against MDR breast cancer.

Long-Term Alteration of Reactive Oxygen Species Led to Multidrug Resistance in MCF-7 Cells

Reactive oxygen species (ROS) play an important role in multidrug resistance (MDR). This study aimed to investigate the effects of long-term ROS alteration on MDR in MCF-7 cells and to explore its underlying mechanism. Our study showed both long-term treatments of H₂O₂ and glutathione (GSH) led to MDR with suppressed iROS levels in MCF-7 cells. Moreover, the MDR cells induced by 0.1 μM H₂O₂ treatment for 20 weeks (MCF-7/ROS cells) had a higher viability and proliferative ability than the control MCF-7 cells. MCF-7/ROS cells also showed higher activity or content of intracellular antioxidants like glutathione peroxidase (GPx), GSH, superoxide dismutase (SOD), and catalase (CAT). Importantly, MCF-7/ROS cells were characterized by overexpression of MDR-related protein 1 (MRP1) and P-glycoprotein (P-gp), as well as their regulators NF-E2-related factor 2 (Nrf2), hypoxia-inducible factor 1 (HIF-1α), and the activation of PI3K/Akt pathway in upstream. Moreover, several typical MDR mediators, including glutathione S-transferase-π (GST-π) and c-Myc and Protein Kinase Cα (PKCα), were also found to be upregulated in MCF-7/ROS cells. Collectively, our results suggest that ROS may be critical in the generation of MDR, which may provide new insights into understanding of mechanisms of MDR.

Reconstituted high density lipoprotein mediated targeted co-delivery of HZ08 and paclitaxel enhances the efficacy of paclitaxel in multidrug-resistant MCF-7 breast cancer cells

In the past decades, reconstituted high density lipoprotein (rHDL) has been successfully developed as a drug carrier since the enhanced HDL-lipids uptake is demonstrated in several human cancers. In this paper, rHDL, for the first time, was utilized to co-encapsulate two hydrophobic drugs: an anticancer drug, paclitaxel (PTX), and a new reversal agent for P-gp (P-glycoprotein)-mediated multidrug resistance (MDR) of cancer, N-cyano-1-[(3,4-dimethoxyphenyl)methyl]-3,4-dihydro-6,7-dimethoxy-N'-octyl-2(1H)-isoquinoline-carboximidamide (HZ08). We proposed this drug co-delivery strategy to reverse PTX resistance. The study aimed to develop a biomimetic nanovector, reconstituted high density lipoprotein (rHDL), mediating targeted PTX-HZ08 delivery for cancer therapy. Using sodium cholate dialysis method, we successfully formulated dual-agent co-delivering rHDL nanoparticles (PTX-HZ08-rHDL NPs) with a typical spherical morphology, well-distributed size (~100nm), high drug encapsulation efficiency (approximately 90%), sustained drug release properties and exceptional stability even after storage for 1month or incubation in 10% fetal bovine serum (FBS) DMEM for up to 2days. Results demonstrated that PTX-HZ08-rHDL NPs significantly enhanced anticancer efficacy in vitro, including higher cytotoxicity and better ability to induce cell apoptosis against both PTX-sensitive and -resistant MCF-7 human breast cancer cell lines (MCF-7 and MCF-7/PTX cells). Mechanism studies demonstrated that these improvements could be correlated with increased cellular uptake of PTX mediated by scavenger receptor class B type I (SR-BI) as well as prolonged intracellular retention of PTX due to the HZ08 mediated drug-efflux inhibition. In addition, in vivo investigation showed that the PTX-HZ08-rHDL NPs were substantially safer, have higher tumor-targeted capacity and have stronger antitumor activity than the corresponding dosage of paclitaxel injection. These findings suggested that rHDL NPs could be an ideal tumor-targeted nanovector for simultaneous transfer of insoluble anticancer drug and drug resistance reversal agents. The PTX-HZ08-rHDL NPs co-delivery system might be a new promising strategy to overcome tumor drug resistance.

HZ08 reverse P-glycoprotein mediated multidrug resistance in vitro and in vivo

Background

Multidrug efflux transporter P-glycoprotein (P-gp) is highly expressed on membrane of tumor cells and is implicated in resistance to tumor chemotherapy. HZ08 is synthesized and studied in order to find a novel P-gp inhibitor.

Methods

MDCK-MDR1 monolayer transport, calcein-AM P-gp inhibition and P-gp ATPase assays were used to confirm the P-gp inhibition capability of HZ08. Furthermore, KB-WT and KB-VCR cells were used to evaluate the P-gp inhibitory activity of HZ08 both in vitro and in vivo.

Results

Results showed that HZ08 was more potent than verapamil in MDCK-MDR1 monolayer transportation model. Meanwhile, P-gp ATPase assay and calcein-AM P-gp inhibition assay confirmed that HZ08 inhibited P-gp ATPase with a calcein-AM IC50 of 2.44±0.31μM. In addition, significantly greater in vitro multidrug resistance reversing effects were observed when vincristine or paclitaxel was used in combination with 10μM HZ08 compared with 10μM verapamil. Moreover, HZ08 could significantly enhance the sensitivity of vincristine with a similar effect like verapamil in both KB-WT and KB-VCR tumor xenograft models.

Conclusions

The novel structure HZ08 could be a potent P-gp inhibitor.

HZ08 reverse the aneuploidy-induced cisplatin-resistance in Gastric cancer by modulating the p53 pathway

We evaluated the influence of DNA aneuploidy on chemotherapy-resistance in human Gastric cancer cell MKN45; we also evaluated the reversal effects of HZ08 on these cells and then preliminary investigated the possible involved pathway. We made use of a pair of human Gastric cancer cell dip-MKN45 (diploid MKN45) and aneu-MKN45 (aneuploid MKN45). Growth inhibition in response to chemotherapeutic drugs was evaluated by CellTiter-Glo Luminescent Cell Viability assay and clone formation assay. Flow cytometry and immuno-assay were applied to evaluate apoptosis and the expression of relative signaling molecules. MKN45 xenograft was generated to evaluate in vivo action. Aneu-MKN45 developed a resistance to cisplatin which could be reversed by HZ08; Flow cytometry and western-blot indicates that HZ08-combination could induce apoptosis and increase the expression of apoptosis-related biomarkers on aneu-MKN45; in vivo study also reflect the same correlation between aneuploidy and cisplatin-resistance, which could be antagonized by HZ08 combination; When investigating the involved pathway, in anue-MKN45, the expression of molecules in p53 pathway was decreased; HZ08 could increase the expression of p53 down-stream molecules as well as elevate the activity of p53, while inhibiting Mdm2, the major negative regulator of p53; p53 inhibitor Pifithrin-α could completely abrogate HZ08's synergism effects, and mimic cisplatin-resistance on dip-MKN45.Lower p53 pathway expression that attenuates cisplatin-induced apoptosis might be at least partly the reason of cisplatin-resistance occurred in aneuploid MKN45 both in vitro and in vivo; Combination of HZ08 could sensitize cisplatin-induced apoptosis through the activation of the p53 pathway, therefore represented a synergism effect on aneuploid MKN45 cells.

In vitro and in vivo study of dolichyl phosphate on the efflux activity of P-glycoprotein at the blood-brain barrier

It has been commonly recognized that accumulated amyloid-β (Aβ) in the brain plays a crucial role in the pathogenesis of Alzheimer's disease (AD). Since the deficiency of the P-glycoprotein (P-gp) at the blood-brain barrier (BBB) in AD may aggravate Aβ deposition and the P-gp reversal agents display lower selectivity of the action, to selectively restore activity of the efflux pump is eagerly required. This study was designed to investigate the influence of dolichyl-phosphate (dolichyl-P) on the P-gp at the BBB. The results revealed that treatment with dolichyl-P increased transendothelial transfer of Rhodamine123 (Rh123) and Aβ42 from the apical compartment to the basolateral compartment but reduced that from the basolateral compartment to the apical compartment in the co-culture of rat brain microvessel endothelial cells (rBMECs) and astrocytes, down regulated P-gp expression in rBMECs and significantly elevated content of Rh123 in rat cortex and hippocampus tissues. The present results implied that accumulated dolichyl-P in the brain may exert an important role in the depression of the P-gp at the BBB, which may suggest valuable clues to promote function of the pump at the BBB in AD.

Modulation of P-glycoprotein in rat brain microvessel endothelial cells under oxygen glucose deprivation

Objectives

To investigate modulation of P-glycoprotein (P-gp) in rat brain microvessel endothelial cells (rBMECs) under oxygen glucose deprivation (OGD).

Methods

The coculture of rBMECs and astrocytes was established to investigate the time course of P-gp, tumour necrosis factor-α (TNF-α), endothelin-1 (ET-1), nitric oxide synthase (NOS) and protein kinase C (PKC) expression in the rBMECs as well as rhodamine 123 (Rh123) transendothelial transfer under OGD using Western blot and HPLC, respectively. The influence of pharmacological tools including H398, JKC-301, RES-701-1, L-NMMA, BIM and SN50 on the P-gp expression as well as Rh123 transendothelial transfer was evaluated at 3 h time point of OGD.

Key findings

Elevated P-gp, TNF-α, ET-1, NOS and PKC expression in the rBMECs, as well as increased P-gp efflux activity were observed after 2 h or more time of OGD. Incubation of H398 and other pharmacological tools downregulated P-gp expression and functional activity in the rBMECs at 3 h time point of OGD.

Conclusions

This report suggested that TNF-α, ET-1, NOS and PKC may mediate upregulation of P-gp in the rBMECs under OGD, which may be worthy of being referenced for the investigation of P-gp at the blood–brain barrier in the early period of stroke.

Inhibition of P-glycoprotein and glutathione S-transferase-pi mediated resistance by fluoxetine in MCF-7/ADM cells

Chemotherapy is important in the systematic treatment of breast cancer. While multidrug resistance (MDR) is the main obstacle in chemotherapy, a reversal reagent with high reversal effect but low toxicity is the hotspot issue at present to overcome MDR. Antidepressant fluoxetine (FLX) is a potential new highly effective chemosensitizer, however, the possible mechanism is unclear. In this study, the effect of FLX on multidrug resistance mediated by P-glycoprotein (P-gp) and glutathione S-transferase-pi (GST-π) were researched in resistant/sensitive breast cancer cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) was used to determine the cells viability after being incubated with FLX/Adriamycin (ADM)/Paclitaxel (PTX) alone or FLX-ADM, FLX-PTX combination. Western blot was performed to assay the expression of P-gp and GST-π proteins. Reverse transcriptase polymerase chain reaction (RT-PCR) and quantitative real-time PCR (qRT-PCR) were performed to assay the level of MDR1 mRNA. The results showed that pre-treatment with FLX enhance cytotoxicity significantly both on resistant and sensitive cells, downregulated the expression of P-gp and GST-π proteins in resistance cells, decreased the MDR1 mRNA by FLX-PTX combination only. No P-gp and GST-π were detected in sensitive cells. Our research thus indicated that FLX reverse the breast cancer cell's resistance and enhance the chemosensitivity by regulating P-gp and GST-π levels.

Alteration in P-glycoprotein at the blood–brain barrier in the early period of MCAO in rats

Objectives

The aim of this work was to investigate the alteration in P-glycoprotein (P-gp) at the blood–brain barrier (BBB) after middle cerebral artery occlusion (MCAO) in rats.

Methods

Permanent MCAO was verified via 2,3,5-triphenyltetrazolium staining and hematoxylin-eosin staining. The expression of P-gp, matrix metalloproteinase-2 (MMP-2), MMP-9, claudin-5, tumour necrosis factor-α (TNF-α) and nitric oxide synthase (NOS) at the BBB was evaluated using western blot or immunostaining analysis. The content of fluorescein sodium (NaF), rhodamine-123 and nimodipine in ischaemic brain tissues was determined using high-performance liquid chromatography.

Key findings

Elevated expression of P-gp at the BBB and decreased concentration of P-gp substrates in the ischaemic brain tissues were observed within 4 h after MCAO. However, at 6 h after MCAO, the concentration of P-gp substrates in the ischaemic hemisphere began to rise even though the expression of P-gp was still increased. Moreover, the expression of claudin-5 was decreased; contrarily, the expression of MMP-2, MMP-9, TNF-α as well as NOS gradually increased within 6 h after MCAO.

Conclusions

P-gp plays a crucial role in limiting the entrance of agents into the brain after MCAO and the specific regulation of P-gp expression/activity may provide an important approach for the improvement of pharmacotherapy in ischaemic stroke.

Fluoxetine synergys with anticancer drugs to overcome multidrug resistance in breast cancer cells

Multidrug resistance (MDR) is the main obstacle in breast cancer chemotherapy, a reversal reagent with high reversal effect but low toxicity is the hotpot issue at present. The antidepressant fluoxetine (FLX) is a new highly effective chemosensitizer; however, the possible mechanism of FLX in reversal of MDR is unclear. In this study, the effect of FLX on MDR mediated by apoptosis was researched in resistant/sensitive breast cancer cells, which treated by FLX/adriamycin (ADM)/paclitaxel (PTX) alone or FLX-ADM, FLX-PTX combination. Apoptosis assay demonstrated that FLX combined with ADM enhanced the proportion of apoptosis remarkably in MCF-7/ADM but not MCF-7 cells; however, increased the apoptosis rates in both cells when FLX-PTX combination. Results of apoptosis proteins assay showed a upgrade of p53 and a downgrade of Bcl-2 level by FLX-ADM or FLX-PTX combinations in both cells. Our findings indicated that by synergism with anticancer drugs, FLX modulation of apoptosis via targeting p53 and Bcl-2 expression, FLX reverse the breast cancer cell's resistance and enhance the chemosensitivity to ADM and PTX.