Preliminary evaluation of caspases-dependent apoptosis signaling pathways of free and HPMA copolymer-bound doxorubicin in human ovarian carcinoma cells.

The purpose of the study was to examine the role of caspases in signaling pathways of apoptosis induced by free doxorubicin (DOX) and HPMA copolymer-bound DOX (P(GFLG)-DOX) in human ovarian carcinoma cells. Sensitive A2780 and DOX resistant A2780/AD cells were exposed to different doses of drugs within 12, 18, 24 and 36 h. Caspase activity, expression of genes encoding human caspases 1-10, Apaf-1 and bcl-2 proteins and apoptosis were studied. In sensitive cells both free and P(GFLG)-DOX activated caspases 3, 7 and 9. In addition, P(GFLG)-DOX activated caspases 6 and 8. In resistant cells apoptosis induced by free DOX depended on the activation of caspases 2, 7 and 9, while caspase 3 was not involved; this explains the low degree of apoptosis induced by free DOX in resistant cells. P(GFLG)-DOX triggered the additional caspases 3, 6 and 8. A more pronounced degree of caspase activation and apoptosis after the action of P(GFLG)-DOX depended on the inhibition of bcl-2-encoded cellular defensive mechanisms and a more significant activation of Apaf-1. It was concluded that HPMA copolymer-bound DOX induced additional caspase-dependent apoptosis signaling pathways and the degree of the induction was higher, which led to more pronounced apoptosis when compared to free DOX.     

Characterization and targeting ability evaluation of cell-penetrating peptide LyP-1 modified alginate-based nanoparticles

Doxorubicin hydrochloride (DOX) shows a powerful treatment effect on breast cancer. However, for its indiscriminate distribution after systemic administration, the therapeutic response of DOX will reduce and even result in serious adverse reactions during the long-term administration. To achieve better treatment, in this study we established a non-condensing sodium alginate-based nanoparticle-encapsulated DOX (DOX/NP), the surface of which was modified with cell-penetrating peptide LyP-1 (namely LyP-1-DOX/NP) to attain active targeting towards breast cancer cells. The size of LyP-1-DOX/NP was 138.50 ± 4.65 nm, with a polydispersity index (PDI) of 0.22 ± 0.02, and the zeta potential was 18.60 ± 0.49 mV. The drug loading efficiency (DLE) for the preparation was 91.21 ± 2.01%, with an encapsulation efficiency (EE) of 12.37 ± 0.35%. The nanoparticles exhibited good stability in vitro and slower release trend compared with free DOX in PBS at pH7.4. In vitro cytopharmacodynamics showed that LyP-1-DOX/NP had an excellent anti-breast cancer effect against MDA-MB-231 cells by the MTT test. The uptake amount of LyP-1-DOX/NP by MDA-MB-231 cells was much higher than that of free DOX or unmodified DOX/NP at all time points. Further in vivo pharmacokinetics studies showed that the concentration of LyP-1-DOX/NP was higher than that of free DOX or DOX/NP both in plasma and in tumor, suggesting its favorable long circulation and enhancing targeting property. The present study provides a promising strategy for using the LyP-1 cell-penetrating peptide to modify nanoparticles for enhancing their targeting ability towards breast cancer.

Doxorubicin hydrochloride (DOX) shows a powerful treatment effect on breast cancer.     

RAFT polymerization mediated core–shell supramolecular assembly of PEGMA-co-stearic acid block co-polymer for efficient anticancer drug delivery

In this work, core–shell supramolecular assembly polymeric nano-architectures containing hydrophilic and hydrophobic segments were synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. Herein, polyethylene glycol methyl ether methacrylate (PEGMA), and stearic acid were used to synthesize the poly(PEGMA) homopolymer and stearyl ethyl methacrylate (SEMA), respectively. Then, PEGMA and SEMA were polymerized through controlled RAFT polymerization to obtain the final diblock copolymer, poly(PEGMA-co-SEMA) (BCP). Model anticancer drug, doxorubicin (DOX) was loaded on BCPs. Interestingly, efficient DOX release was observed at acidic pH, similar to the cancerous environment pH level. Significant cellular uptake of DOX loaded BCP50 (BCP50-DOX) was observed in MDA-MB-231 triple negative breast cancer cells and resulted in a 35 fold increase in anticancer activity against MDA MB-231 cells compared to free DOX. Scanning electron microscopy (SEM) imaging confirmed the apoptosis mediated cellular death. These core–shell supramolecular assembly polymeric nano-architectures may be an efficient anti-cancer drug delivery system in the future.

In this work, core–shell supramolecular assembly polymeric nano-architectures containing hydrophilic and hydrophobic segments were synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization.     

In vitro reversal MDR of human carcinoma cell line by an antisense oligodeoxynucleotide-doxorubicin conjugate.

A conjugate of antisense oligodeoxynucleotide (AS ODN) covalently linked with deoxorubicin (DOX) was synthesized. Its properties and antitumour activity in human carcinoma DOX resistant cells (KB-A-1) were investigated in vitro. The results showed that the conjugate was strongly stable both in Dulbecco's Phosphate-Buffered Saline (PBS) and in culture medium. The intracellular concentration of the conjugate was higher than that of the AS DON by HPLC analysis. The conjugate showed potent dose-dependent inhibition to the growth of KB-A-1 cells. Chemosensitivity of KB-A-1 cells to DOX was also investigated in vitro. When the cells were first exposed to the conjugate (0.5 microM) and then exposed to DOX for 24 h, the IC50 value of DOX decreased from 21.5 to 2.2 microM. In contrast, when treated with the mixture of the same concentration of the AS ODN with equivalent DOX, the IC50 value of DOX was 16.8 microM. Intracellular DOX concentration was detected in KB-A-1 treatment with the conjugate in vitro by HPLC. The results showed that the intracellular DOX concentration was 6.4-fold increased in KB-A-1 cells treated with the conjugate compared to treatment with DOX alone. In contrast, 1.8-fold increasing was observed when treated with the AS ODN. Western blot analysis showed a significantly decrease in the amount of P-glycoprotein in KB-A-1 cells. These results suggest that the conjugate is effective in reversing multidrug resistance. Certainly, further studies are conducting to explore the antitumour effect of the conjugate in vivo.     

Biocompatible supramolecular pseudorotaxane hydrogels for controllable release of doxorubicin in ovarian cancer SKOV-3 cells

A series of injectable and biocompatible delivery DOX-loaded supramolecular hydrogels were fabricated by using presynthesized DOX-2N-β-CD, Pluronic F-127 and α-CD through host–guest interactions and cooperative multivalent hydrogen bonding interactions. The compositions and morphologies of these hydrogels were confirmed by PXRD and SEM measurements. Moreover, the Rheological measurements of these hydrogels were studied and the studies found that they showed a unique thixotropic behavior, indicting a fast self-healing property after the continuous oscillatory shear stress. Using α-CD as a capping agent, slow and sustained DOX release was observed at different pH values after 72 h. The amount of DOX released at pH 7.4 was determined to be 49.0% for hydrogel 1, whereas the releasing amount of the DOX was increased to 66.3% for hydrogel 1 during the same period at pH 5.5 (P < 0.05), indicating a higher release rate of the drug under more acidic conditions. Taking hydrogel 1 as a representative material, the toxicities of DOX and hydrogel 1 on ovarian cancer cells (SKOV-3) at different exposure durations were examined. The results revealed that hydrogel 1 was less cytotoxic than free DOX to SKOV-3 cells (P < 0.05), suggesting sustained release by these hydrogels in the presence of ovarian cancer cells. It is anticipated that this exploration can provide a new strategy for preparing drug delivery systems.

A series of injectable and biocompatible delivery DOX-loaded supramolecular hydrogels were fabricated by using presynthesized DOX-2N-β-CD, Pluronic F-127 and α-CD through host–guest interactions and cooperative multivalent hydrogen bonding interactions.     

In vitro and in vivo intracellular liposomal delivery of antisense oligonucleotides and anticancer drug.

The specific aims of this investigation were (1) to show that conventional and PEGylated liposomes can penetrate cancer cells in vitro and in vivo; (2) to demonstrate that liposomes can be successfully used both for cytoplasmic and nuclear delivery of therapeutics, including anticancer drugs and antisense oligonucleotides; (3) to examine the specific activity of anticancer drugs and nucleotides delivered inside tumor cells by PEGylated liposomes; and (4) to confirm that simultaneous inhibition of pump and nonpump cellular resistance by liposomal ASO can substantially enhance the antitumor activity of traditional well established anticancer drugs in mice bearing xenografts of human multidrug resistant ovarian carcinoma. Experimental results show that PEGylated liposomes are capable of penetrating directly into tumor cells after systemic administration in vivo and do successfully provide cytoplasmic and nuclear delivery of encapsulated anticancer drug (doxorubicin, DOX) and antisense oligonucleotides (ASO). Encapsulation of DOX and ASO into liposomes substantially increased their specific activity. Simultaneous suppression of pump and nonpump resistance dramatically enhanced the ability of DOX for inducing apoptosis leading to higher in vitro cytotoxicity and in vivo antitumor activity.     

Modulation of P-glycoprotein function and reversal of multidrug resistance by (-)-epigallocatechin gallate in human cancer cells.

Multidrug resistance (MDR) is a major obstacle in the chemotherapeutic treatment of many human cancers. In this study, the reversal of P-glycoprotein (P-gp) mediated multidrug resistance by (-)-epigallocatechin gallate (EGCG) and its molecular mechanism were investigated. A three-dimensional model of carboxyl-terminal nucleotide binding domain (NBD2) from P-gp was built by homology modeling. The structural model of the complex indicates that EGCG was tightly bound to the ATP-binding site of NBD2. EGCG modulated the function of P-gp and increased the intracellular accumulation of chemotherapeutic agent doxorubicin (DOX) in drug-resistant KB-A1 cells. When KB-A1 cells were exposed to 10 microg/ml DOX combined with 10, 30, 50 microM EGCG for 4 h, the intracellular concentrations of DOX were increased 1.5, 1.9, 2.3 times, respectively compared with DOX alone treatment. In vitro EGCG potentiated the cytotoxicity of DOX to drug-resistant KB-A1 cells. In KB-A1 cell xenograft model, EGCG could also enhance the efficacy of DOX and increased the DOX concentration in the resistant tumors. Thus, these results suggest that EGCG modulated the function of P-gp and reversed P-gp mediated multidrug resistance in human cancer cells.     

Properties of HPMA copolymer-doxorubicin conjugates with pH-controlled activation: effect of polymer chain modification.

Various conjugates of anticancer drug doxorubicin (DOX) covalently attached via hydrolytically degradable hydrazone bond to water-soluble N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer drug carriers were synthesized. Three types of precursors containing either positively or negatively charged groups or a hydrophobic substituent were employed. In vitro incubation of the conjugates in buffers showed relative stability at pH 7.4 (modelling blood) and a fast DOX release at pH 5 (modelling intracellular environment). The presence of carboxylic groups in the copolymer structure resulted in an increase in the DOX release rate of 15-20% while no effect of the introduction of positively charged groups was observed if compared with the unmodified conjugate. Self-assembling of the oleoyl groups-containing conjugate led into formation of polymeric micelles with high apparent molecular weight (M(w)=170,000) in aqueous solution and resulted in a decrease in the DOX release rate of approximately 20%. The cytostatic activity of the conjugates tested on several cancer cell lines was comparable with that of free DOX.HCl, depending on the sensitivity of a particular cell line to DOX. All the conjugates showed a much higher antitumour activity in vivo than the free drug tested in mice bearing EL4 T-cell lymphoma and treated using the therapeutic regime of drug administration. The highest activity (100% long-term survivors) exhibited polymer-DOX conjugate containing negatively charged GFLG sequences.     

Synthesis,antitumor activity and molecular mechanism of doxorubicin conjugated trimethyl-chitosan polymeric micelle loading Beclin1 siRNA for drug-resisted bladder cancer therapy

Herein, we describe a convenient approach for the preparation of a polymeric micelle using doxorubicin (DOX) conjugated trimethyl-chitosan (TMC) with Beclin-1 siRNA (Si-Beclin1/DOX-TMC). This micelle displayed a potent capacity for autophagy inhibition and reversed drug-resistance to DOX in BIU-87/ADR cell lines. The Si-Beclin1/DOX-TMC micelle was highly cytotoxic to both drug-sensitive BIU-87 and drug-resistant BIU-87/ADR cells. Its capacity to reverse drug-resistance was dependent upon upregulation of autophagy levels in BIU-87/ADR cells. DOX was conjugated to TMC via a pH-sensitive Schiff base, which responded to the acidic lysosome microenvironment and resulted in the cytoplasmic release of DOX. The structure of DOX conjugation to the TMC polymeric micelle was characterized by NMR, GPC, TEM and DLS. DOX release profiles in different pH environment were determined by HPLC. Cellular uptake, changes to nuclei morphology and formation of autophagosomes were observed using a fluorescence microscope. Finally, in vivo antitumor activity of systemic Si-Beclin1/DOX-TMC micelle administration was evaluated in BIU-87/ADR xenograft models and Si-Beclin1/DOX-TMC micelles showed significantly suppressed tumor growth.

Herein, we describe a convenient approach for the preparation of a polymeric micelle using doxorubicin (DOX) conjugated trimethyl-chitosan (TMC) with Beclin-1 siRNA (Si-Beclin1/DOX-TMC).     

HPMA copolymers with pH-controlled release of doxorubicin: in vitro cytotoxicity and in vivo antitumor activity.

Data on the synthesis, physicochemical characterisation and in vitro and in vivo biological properties of the new, nontargeted or antibody-targeted polymer-doxorubicin conjugates designed as anticancer drugs are presented. In the conjugates, the anticancer drug doxorubicin (DOX) is attached to the polymer carrier via a simple hydrolytically labile spacer containing either a hydrazone bond or cis-aconitic acid residue. In vitro incubation of the conjugates in buffers led to a fast DOX release from the polymer at pH 5 (modelling intracellular environment) while at pH 7.4 (modelling blood) the conjugates are relatively stable. Cytotoxicity of the conjugates to T cell lymphoma EL4 depended on the detailed structure of the spacer and the method used for antibody attachment and was much higher compared with the effect of similar classic conjugates (DOX attached to the polymer via enzymatically degradable spacer). In both protective and therapeutic regimes of drug administration, the in vivo anti-tumor activity of the hydrazone conjugates containing only DOX was significantly enhanced (T cell lymphoma EL4, C57BL/10 mice) in comparison with free DOX or classic PK1, the PHPMA-DOX conjugate clinically tested at present. Increasing the molecular weight of the polymer carrier resulted in a more pronounced in vivo antitumor effect. Antibody-targeted conjugates with DOX bound via hydrazone bond exhibited even more extensive inhibition of the tumor growth with some long-term survivors. No survivors were observed after treatment of mice with free DOX or the nontargeted PHPMA-DOX conjugate.     

Doxorubicin loaded iron oxide nanoparticles overcome multidrug resistance in cancer in vitro

Multidrug resistance (MDR) is characterized by the overexpression of ATP-binding cassette (ABC) transporters that actively pump a broad class of hydrophobic chemotherapeutic drugs out of cancer cells. MDR is a major mechanism of treatment resistance in a variety of human tumors, and clinically applicable strategies to circumvent MDR remain to be characterized. Here we describe the fabrication and characterization of a drug-loaded iron oxide nanoparticle designed to circumvent MDR. Doxorubicin (DOX), an anthracycline antibiotic commonly used in cancer chemotherapy and substrate for ABC-mediated drug efflux, was covalently bound to polyethylenimine via a pH sensitive hydrazone linkage and conjugated to an iron oxide nanoparticle coated with amine terminated polyethylene glycol. Drug loading, physiochemical properties and pH lability of the DOX-hydrazone linkage were evaluated in vitro. Nanoparticle uptake, retention, and dose-dependent effects on viability were compared in wild-type and DOX-resistant ABC transporter over-expressing rat glioma C6 cells. We found that DOX release from nanoparticles was greatest at acidic pH, indicative of cleavage of the hydrazone linkage. DOX-conjugated nanoparticles were readily taken up by wild-type and drug-resistant cells. In contrast to free drug, DOX-conjugated nanoparticles persisted in drug-resistant cells, indicating that they were not subject to drug efflux. Greater retention of DOX-conjugated nanoparticles was accompanied by reduction of viability relative to cells treated with free drug. Our results suggest that DOX-conjugated nanoparticles could improve the efficacy of chemotherapy by circumventing MDR.     

Up-regulation of glutathione-related genes,enzyme activities and transport proteins in human cervical cancer cells treated with doxorubicin

Doxorubicin (DOX), one of the most effective anticancer drugs, acts in a variety of ways including DNA damage, enzyme inhibition and generation of reactive oxygen species. Glutathione (GSH) and glutathione-related enzymes including: glutathione peroxidase (GPX), glutathione reductase (GSR) and glutathione S-transferases (GST) may play a role in adaptive detoxification processes in response to the oxidative stress, thus contributing to drug resistance phenotype. In this study, we investigated effects of DOX treatment on expression and activity of GSH-related enzymes and multidrug resistance-associated proteins in cultured human cervical cancer cells displaying different resistance against this drug (HeLa and KB-V1).Determination of expression level of genes encoding GST isoforms and MRP proteins (GCS, GPX, GSR, GSTA1-3, GSTM1, GSTP1, ABCC1-3, MGST1-3) was performed using StellARray™ Technology. Enzymatic activities of GPX and GSR were measured using biochemical methods. Expression of MRP1 was examined by immunofluorescence microscopy.This study showed that native expression levels of GSTM1 and GSTA3 were markedly higher in KB-V1 cells (2000-fold and 200-fold) compared to HeLa cells. Resistant cells have also shown significantly elevated expression of GSTA1 and GSTA2 genes (200-fold and 50-fold) as a result of DOX treatment. In HeLa cells, exposure to DOX increased expression of all genes: GSTM1 (7-fold) and GSTA1-3 (550-fold, 150-fold and 300-fold). Exposure to DOX led to the slight increase of GCS expression as well as GPX activity in KB-V1 cells, while in HeLa cells it did not. Expression of ABCC1 (MRP1) was not increased in any of the tested cell lines.Our results indicate that expression of GSTM1 and GSTA1-3 genes is up-regulated by DOX treatment and suggest that activity of these genes may be associated with drug resistance of the tested cells. At the same time, involvement of MRP1 in DOX resistance in the given experimental conditions is unlikely.     

Amino acid-modified PAMAM dendritic nanocarriers as effective chemotherapeutic drug vehicles in cancer treatment: a study using zebrafish as a cancer model

The use of nanomaterials for drug delivery offers many advantages including the targeted delivery of drugs and their controlled release. Nonetheless, entry into the target cells remains a challenge for many nanomaterials used for drug delivery. Moreover, cellular uptake limits the therapeutic efficiency of many anticancer drugs. An important goal is to increase the specific accumulation of these nanoparticles (NPs) at the desired cancerous tissues. Notably, cancer cells show a high demand for some amino acids and we have used this knowledge to develop novel carrier systems. In this study, drug carriers were produced by the conjugation of multiple amino acids such as l-histidine (H) and l-cysteine (C) or single amino acids such as only H with the G4.5 dendrimers (G) to produce GHC aggregates and GH NP carriers, respectively. Doxorubicin was loaded into the G4.5, GH, and GHC dendrimers (G/DOX, GH/DOX and GHC/DOX, respectively) and the release mechanism was demonstrated at pH 7.4 and pH 5.0. GH/DOX and GHC/DOX showed better stability under physiological conditions than the dendrimer alone (G/DOX). GH/DOX and GHC/DOX exhibited higher inhibition of HeLa cell proliferation in in vitro and in vivo studies in zebrafish, confirming the early release of DOX by disrupting the endosomal membrane and triggering the destabilization of carriers at a lower pH of 5.0.

The use of nanomaterials for drug delivery offers many advantages including the controlled release and their targeted delivery.     

一株耐阿霉素小鼠白血病L1210细胞系的建立及耐药机制的研究

肿瘤细胞耐药是肿瘤病人治疗失败的主要原因。通过连续递增阿霉素浓度的方法,筛选出一株对阿霉素的耐药性增高91.2倍的小鼠白血病L1210细胞系(L1210/DOX)。该细胞与L1210敏感细胞的增殖速度相似,倍增时间分别为15和15.5h。电子显微镜结果显示L1210/DOX细胞的形状和大小仍保持典型的白血病细胞态,与敏感株相似。该耐药细胞系与高三尖杉酯碱和长春新碱有交叉耐药,其半数抑制浓度(IC_(50))分别为敏感株的31.4和33.4倍,但对烷化剂马法兰无交叉耐药,呈多药耐药性。细胞内药物浓度检测的结果为阿霉素在L1210/DOX细胞内蓄积浓度仅为敏感细胞的9％。斑点杂交的结果显示L1210/DOX的多药耐药基因(MDR-1)mRNA水平显著高于敏感株。然而,二者的谷胱甘肽S-转移酶活性无显著差异。以上结果提示MDR-1基因的过度表达在L1210/DOX细胞耐药中起着重要作用;L1210/DOX细胞可经DBA/2小鼠传代,将成为体内耐药的小鼠模型。     

Characterization of the pH of folate receptor-containing endosomes and the rate of hydrolysis of internalized acid-labile folate-drug conjugates

Despite the widely accepted assumption that most endosomal compartments are acidic, evaluation of the efficiency of pH-dependent drug release from a ligand-targeted drug conjugate during receptor-mediated endocytosis is lacking. Therefore, we have characterized the kinetics of pH-dependent drug release from a model folate-drug conjugate during folate receptor (FR)-mediated endosomal trafficking. For this purpose, we synthesized an acid-labile folate-fluorescence resonance energy transfer reporter (ALFR) that emits green fluorescence (BODIPY FL, 6-((4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diazas-indacene-3-propionyl)amino)hexanoic acid) only after acid-catalyzed hydrolysis of the acyl hydrazone linker. In a cell-free system, cleavage of ALFR was found to be efficient only at acidic pH values (t1/2=1.95, 4.63, and 75 h at pH 4, 5, and 6, respectively) and essentially resistant to hydrolysis at pH 7. Curiously, when applied to folate receptor-expressing cancer cells, the acid-labile folate-linked probe exhibited little or no recovery of BODIPY FL fluorescence (green), even after 55 h of incubation, arguing very inefficient cleavage within the FR endocytic pathway. To understand this unanticipated observation, we measured the pH of FR-containing endosomes using ratiometric fluorescence microscopy and observed that most FR+ endosomes are only mildly acidic (average approximately pH 6.5). Taken together, these data argue that the FR-trafficking pathway does not involve acidic compartments and that acyl hydrazone linkers may constitute a poor option for FR-mediated drug delivery.     

Defective Acidification in Human Breast Tumor Cells and Implications for Chemotherapy

Multidrug resistance (MDR) is a significant problem in the treatment of cancer. Chemotherapeutic drugs distribute through the cyto- and nucleoplasm of drug-sensitive cells but are excluded from the nucleus in drug-resistant cells, concentrating in cytoplasmic organelles. Weak base chemotherapeutic drugs (e.g., anthracyclines and vinca alkaloids) should concentrate in acidic organelles. This report presents a quantification of the pH for identified compartments of the MCF-7 human breast tumor cell line and demonstrates that (a) the chemotherapeutic Adriamycin concentrates in acidified organelles of drug-resistant but not drug-sensitive cells; (b) the lysosomes and recycling endosomes are not acidified in drug-sensitive cells; (c) the cytosol of drug-sensitive cells is 0.4 pH units more acidic than the cytosol of resistant cells; and (d) disrupting the acidification of the organelles of resistant cells with monensin, bafilomycin A1, or concanamycin A is sufficient to change the Adriamycin distribution to that found in drug-sensitive cells, rendering the cell vulnerable once again to chemotherapy. These results suggest that acidification of organelles is causally related to drug resistance and is consistent with the hypothesis that sequestration of drugs in acidic organelles and subsequent extrusion from the cell through the secretory pathways contribute to chemotherapeutic resistance.     

TRAIL and doxorubicin combination enhances anti-glioblastoma effect based on passive tumor targeting of liposomes

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a novel anticancer agent for glioblastoma multiforme (GBM). Some GBM cell lines, however, are relatively resistant to TRAIL. Doxorubicin (DOX) can sensitize GBM cells to TRAIL-induced apoptosis, indicating that the combination of DOX and TRAIL may be an effective strategy to kill TRAIL-resistant GBM cells. However, the therapeutic effect is limited by the short serum half-life of TRAIL, chronic cardiac toxicity of DOX, multidrug resistance (MDR) property of GBM cells and poor drug delivery across the blood-brain barrier (BBB). To solve such problems, combination treatment of TRAIL liposomes (TRAIL-LP) and DOX liposomes (DOX-LP) were developed for the first time. The in vitro cytotoxicity study indicated that DOX-LP sensitized GBM cell line U87MG but not normal bovine caruncular epithelial cells (BCECs) to TRAIL-LP-induced apoptosis, demonstrating the safety of the combination treatment. This sensitization was accompanied by up-regulation of death receptor 5 (DR5) expression and caspase activation. Furthermore, the combination therapy of TRAIL-LP and DOX-LP displayed stronger anti-GBM effect than free drugs or liposomal drugs alone in vivo. In summary, the combination treatment reported here showed improved therapeutic effect on GBM. Therefore, it has good potential to become a new therapeutic approach for patients with GBM.     

A doxorubicin–platinum conjugate system: impacts on PI3K/AKT actuation and apoptosis in breast cancer cells

In recent years, the development of a nano-conjugate system for drug delivery applications has gained attention among researchers. Keeping this in mind, in this study, we developed a doxorubicin–platinum conjugate system that targeted breast cancer cell lines. To achieve this, we developed platinum nanoparticles using polyvinylpyrrolidone (PVP). High resolution-transmission electron microscopy (HR-TEM) revealed the occurrence of octopod-shaped platinum nanoparticles. Subsequently, doxorubicin (DOX) was conjugated on the surface of the as-prepared platinum octopods via an in situ stirring method. The physicochemical characterization of the doxorubicin–platinum conjugate system revealed that the PVP of PtNPs interacts with the NH₂ group of doxorubicin via electrostatic interaction/hydrogen bonding. Besides, the doxorubicin–platinum conjugate system exhibited a sustained drug release profile within the cancer cells. Furthermore, the evaluation of the in vitro anticancer efficacy of the doxorubicin–platinum conjugate system in breast cancer cells (MCF-7 and MDA-MB-231) unveiled the induction of apoptosis via intracellular ROS and DNA damage, rather than free DOX and PtNPs. Remarkably, we also perceived that the doxorubicin–platinum conjugate system was strong enough to down-regulate the PI3K/AKT signalling pathway. As a result, the tumour suppressor gene PTEN was activated, which led to the stimulation of a mitochondrion-based intrinsic apoptotic pathway and its downstream caspases, triggering cell death. Hence, our findings suggested that a biologically stable doxorubicin–platinum conjugate system could be an imperative therapeutic agent for anticancer therapy in the near future.

In recent years, the development of a nano-conjugate system for drug delivery applications has gained attention among researchers.     

Development of a pH-sensitive functionalized metal organic framework: in vitro study for simultaneous delivery of doxorubicin and cyclophosphamide in breast cancer

Exploration of an efficient dual-drug based nanocarrier with high drug loading capacity, specific targeting properties, and long-term stability is highly desirable in cancer therapy. Metal–organic frameworks (MOFs) have proven to be a promising class of drug carriers due to their high porosity, crystalline properties with defined structure information, and their potential for further functionalization. To enhance the drug efficacy as well as to overcome the burst effect of drugs, here we synthesized a pH responsive folic acid (FA) and graphene oxide (GO) decorated zeolitical imidazolate frameworks-8 (GO–FA/ZIF-8), for targeted delivery of doxorubicin (DOX) and cyclophosphamide (CP), simultaneously. In this system, DOX molecules were encapsulated in the pores of ZIF-8 during in situ synthesis of ZIF-8 and CP molecules have been captured by the GO surface via hydrogen bonding and π–π interactions as well. Furthermore, the resulting pH-responsive nanocarrier (DOX@ZIF-8/GO–FA/CP) showed in vitro sustained release characteristics (76% of DOX and 80% of CP) by cleavage of chemical bonding and disruption of the MOFs structure under acidic condition (at pH 5.6). Moreover, DOX@ZIF-8/GO–FA/CP has synergistic cytotoxic effects as compared to the combination of both the drugs without ZIF-8/GO–FA when treating MCF-7 and MDA-MB-231 breast cancer cell lines (with a combination index of 0.29 and 0.75 for MCF-7 and MDA-MB-231 cell-lines, respectively). Hence this system can be applied as an effective platform for smart dual drug delivery in breast cancer treatment through its remarkable manageable multidrug release.

Exploration of an efficient dual-drug based nanocarrier with high drug loading capacity, specific targeting properties, and long-term stability is highly desirable in cancer therapy.