Multifunctional magnetic Fe3O4 nanoparticles combined with chemotherapy and hyperthermia to overcome multidrug resistance

Nanoplatform-Mediated Autophagy Regulation and Combined Anti-Tumor Therapy for Resistant Tumors

The overall cancer incidence and death toll have been increasing worldwide. However, the conventional therapies have some obvious limitations, such as non-specific targeting, systemic toxic effects, especially the multidrug resistance (MDR) of tumors, in which, autophagy plays a vital role. Therefore, there is an urgent need for new treatments to reduce adverse reactions, improve the treatment efficacy and expand their therapeutic indications more effectively and accurately. Combination therapy based on autophagy regulators is a very feasible and important method to overcome tumor resistance and sensitize anti-tumor drugs. However, the less improved efficacy, more systemic toxicity and other problems limit its clinical application. Nanotechnology provides a good way to overcome this limitation. Co-delivery of autophagy regulators combined with anti-tumor drugs through nanoplatforms provides a good therapeutic strategy for the treatment of tumors, especially drug-resistant tumors. Notably, the nanomaterials with autophagy regulatory properties have broad therapeutic prospects as carrier platforms, especially in adjuvant therapy. However, further research is still necessary to overcome the difficulties such as the safety, biocompatibility, and side effects of nanomedicine. In addition, clinical research is also indispensable to confirm its application in tumor treatment.

Nanodelivery systems: An efficient and target-specific approach for drug-resistant cancers

BACKGROUND

Cancer treatment is still a global health challenge. Nowadays, chemotherapy is widely applied for treating cancer and reducing its burden. However, its application might be in accordance with various adverse effects by exposing the healthy tissues and multidrug resistance (MDR), leading to disease relapse or metastasis. In addition, due to tumor heterogeneity and the varied pharmacokinetic features of prescribed drugs, combination therapy has only shown modestly improved results in MDR malignancies. Nanotechnology has been explored as a potential tool for cancer treatment, due to the efficiency of nanoparticles to function as a vehicle for drug delivery.

METHODS

With this viewpoint, functionalized nanosystems have been investigated as a potential strategy to overcome drug resistance.

RESULTS

This approach aims to improve the efficacy of anticancer medicines while decreasing their associated side effects through a range of mechanisms, such as bypassing drug efflux, controlling drug release, and disrupting metabolism. This review discusses the MDR mechanisms contributing to therapeutic failure, the most cutting-edge approaches used in nanomedicine to create and assess nanocarriers, and designed nanomedicine to counteract MDR with emphasis on recent developments, their potential, and limitations.

CONCLUSIONS

Studies have shown that nanoparticle-mediated drug delivery confers distinct benefits over traditional pharmaceuticals, including improved biocompatibility, stability, permeability, retention effect, and targeting capabilities.

Nanotechnological approaches for counteracting multidrug resistance in cancer

Every year, cancer accounts for a vast portion of deaths worldwide. Established clinical protocols are based on chemotherapy, which, however, is not tumor-selective and produces a series of unbearable side effects in healthy tissues. As a consequence, multidrug resistance (MDR) can arise causing metastatic progression and disease relapse. Combination therapy has demonstrated limited responses in the treatment of MDR, mainly due to the different pharmacokinetic properties of administered drugs and to tumor heterogeneity, challenges that still need to be solved in a significant percentage of cancer patients. In this perspective, we briefly discuss the most relevant MDR mechanisms leading to therapy failure and we report the most advanced strategies adopted in the nanomedicine field for the design and evaluation of ad hoc nanocarriers. We present some emerging classes of nanocarriers developed to reverse MDR and discuss recent progress evidencing their limits and promises.

Magnetic Hyperthermia for Cancer Treatment: Main Parameters Affecting the Outcome of In Vitro and In Vivo Studies

Magnetic hyperthermia (MHT) is being investigated as a cancer treatment since the 1950s. Recent advancements in the field of nanotechnology have resulted in a notable increase in the number of MHT studies. Most of these studies explore MHT as a stand-alone treatment or as an adjuvant therapy in a preclinical context. However, despite all the scientific effort, only a minority of the MHT-devoted nanomaterials and approaches made it to clinical context. The outcome of an MHT experiment is largely influenced by a number of variables that should be considered when setting up new MHT studies. This review highlights and discusses the main parameters affecting the outcome of preclinical MHT, aiming to provide adequate assistance in the design of new, more efficient MHT studies.

Comprehensive understanding of magnetic hyperthermia for improving antitumor therapeutic efficacy

Magnetic hyperthermia (MH) has been introduced clinically as an alternative approach for the focal treatment of tumors. MH utilizes the heat generated by the magnetic nanoparticles (MNPs) when subjected to an alternating magnetic field (AMF). It has become an important topic in the nanomedical field due to their multitudes of advantages towards effective antitumor therapy such as high biosafety, deep tissue penetration, and targeted selective tumor killing. However, in order for MH to progress and to realize its paramount potential as an alternative choice for cancer treatment, tremendous challenges have to be overcome. Thus, the efficiency of MH therapy needs enhancement. In its recent 60-year of history, the field of MH has focused primarily on heating using MNPs for therapeutic applications. Increasing the thermal conversion efficiency of MNPs is the fundamental strategy for improving therapeutic efficacy. Recently, emerging experimental evidence indicates that MNPs-MH produces nano-scale heat effects without macroscopic temperature rise. A deep understanding of the effect of this localized induction heat for the destruction of subcellular/cellular structures further supports the efficacy of MH in improving therapeutic therapy. In this review, the currently available strategies for improving the antitumor therapeutic efficacy of MNPs-MH will be discussed. Firstly, the recent advancements in engineering MNP size, composition, shape, and surface to significantly improve their energy dissipation rates will be explored. Secondly, the latest studies depicting the effect of local induction heat for selectively disrupting cells/intracellular structures will be examined. Thirdly, strategies to enhance the therapeutics by combining MH therapy with chemotherapy, radiotherapy, immunotherapy, photothermal/photodynamic therapy (PDT), and gene therapy will be reviewed. Lastly, the prospect and significant challenges in MH-based antitumor therapy will be discussed. This review is to provide a comprehensive understanding of MH for improving antitumor therapeutic efficacy, which would be of utmost benefit towards guiding the users and for the future development of MNPs-MH towards successful application in medicine.

Study on preparation, characterization and multidrug resistance reversal of red blood cell membrane-camouflaged tetrandrine-loaded PLGA nanoparticles

The multidrug resistance in tumor (MDR) is a major barrier to efficient cancer therapy. Modern pharmacological studies have proven that tetrandrine (TET) has great potential in reversing MDR. However, it has a series of medication problems in clinic such as poor water solubility, low oral bioavailability and short half-life in vivo. Aiming at the above problems, red blood cell membrane-camouflaged TET-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (RPTNs) had been developed. The RPTNs had spherical shell-core double layer structure with average particle size of 164.1 ± 1.65 nm and encapsulation efficiency of 84.1% ± 0.41%. Compared with TET-PLGA nanoparticles (PTNs), the RPTNs reduced RAW 264.7 macrophages’ swallowing by 32% due to its retention of natural membrane proteins. The cumulative drug release of RPTNs was 81.88% within 120 h. And pharmacokinetic study showed that the blood half-life of RPTNs was 19.38 h, which was 2.95 times of free drug. When RPTNs of 2 μg/mL TET were administered in combination with adriamycin (ADR), significant MDR reversal effect was observed in drug-resistant cells MCF-7/ADR. In a word, the RPTNs hold potential to improve its efficacy and broaden its clinical application.

Evolution of Magnetic Hyperthermia for Glioblastoma Multiforme Therapy

Glioblastoma multiforme (GBM) is the most common and aggressive type of glial tumor, and despite many recent advances, its prognosis remains dismal. Hence, new therapeutic approaches for successful GBM treatment are urgently required. Magnetic hyperthermia-mediated cancer therapy (MHCT), which is based on heating the tumor tissues using magnetic nanoparticles on exposure to an alternating magnetic field (AMF), has shown promising results in the preclinical studies conducted so far. The aim of this Review is to evaluate the progression of MHCT for GBM treatment and to determine its effectiveness on the treatment either alone or in combination with other adjuvant therapies. The preclinical studies presented MHCT as an effective treatment module for the reduction of tumor cell growth and increase in survival of the tumor models used. Over the years, much research has been done to prove MHCT alone as the missing notch for successful GBM therapy. However, very few combinatorial studies have been reported. Some of the clinical studies carried out so far depicted that MHCT could be applied safely while possessing minimal side effects. Finally, we believe that, in the future, advancements in magnetic nanosystems might contribute toward establishing MHCT as a potential treatment tool for glioma therapy.

Recent advances and future prospects of iron oxide nanoparticles in biomedicine and diagnostics

Superparamagnetic iron oxide nanoparticles (SPIONs) are considered as chemically inert materials and, therefore, being extensively applied in the areas of imaging, targeting, drug delivery and biosensors. Their unique properties such as low toxicity, biocompatibility, potent magnetic and catalytic behavior and superior role in multifunctional modalities have epitomized them as an appropriate candidate for biomedical applications. Recent developments in the area of materials science have enabled the facile synthesis of Iron oxide nanoparticles (IONPs) offering easy tuning of surface properties and surface functionalization with desired biomolecules. Such developments have enabled IONPs to be easily accommodated in nanocomposite platform or devices. Additionally, the tag of biocompatible material has realized their potential in myriad applications of nanomedicines including imaging modalities, sensing, and therapeutics. Further, IONPs enzyme mimetic activity pronounced their role as nanozymes in detecting biomolecules like glucose, and cholesterol etc. Hence, based on their versatile applications in biomedicine, the present review article focusses on the current trends, developments and future prospects of IONPs in MRI, hyperthermia, photothermal therapy, biomolecules detection, chemotherapy, antimicrobial activity and also their role as the multifunctional agent in diagnosis and nanomedicines.

An Intelligent and Tumor-Responsive Fe2+ Donor and Fe2+-Dependent Drugs Cotransport System

Fe²⁺ plays an essential role for artemisinin (ART)-based drugs in anticancer therapy. As a result, it is important to realize these two agents' cotransport for improving antitumor efficacy. We utilized a kind of alternating magnetic field (AMF) and tumor-responsive material-mesoporous Fe₃O₄ (mFe₃O₄)-to encapsulate ART. After that, the outer surface of mFe₃O₄ was capped with multifunctional hyaluronic acid (HA), which was used not only as a smart gatekeeper but also as a tumor targeting moiety. In vitro and in vivo studies proved that ART can be encapsulated in HA-mFe₃O₄ and protected by HA coating which could effectively avoid premature release during in vivo circulation. HA-mFe₃O₄/ART could be taken up by MCF-7 tumor cells via CD44 receptor-mediated endocytosis and locate at acidic lysosome. Subsequently, "HA gate" could be degraded by acidity and hyaluronidase. Then this system synchronously released Fe²⁺ and ART at the same site. Fe²⁺ can nonenzymatically convert ART to ROS for killing cancer cells. Under AMF irradiation, HA-mFe₃O₄ could not only effectively convert electromagnetic wave into heat for tumor thermal therapy but also generate high levels of reactive oxygen species (ROS) for tumor dynamic therapy. These results demonstrated that the antitumor efficacy of HA-mFe₃O₄/ART in vivo significantly enhanced 3.7 times compared with free ART. Combining with AMF, it further improved 3.9 times (V/V0 of 0.11), suggesting the successful combined application of HA-mFe₃O₄/ART and AMF for tumor treatment. It is believed that HA-mFe₃O₄/ART is a promising system for Fe²⁺-dependent drugs to improve their therapeutic effect.

Inorganic Nanocarriers Overcoming Multidrug Resistance for Cancer Theranostics

Cancer multidrug resistance (MDR) could lead to therapeutic failure of chemotherapy and radiotherapy, and has become one of the main obstacles to successful cancer treatment. Some advanced drug delivery platforms, such as inorganic nanocarriers, demonstrate a high potential for cancer theranostic to overcome the cancer-specific limitation of conventional low-molecular-weight anticancer agents and imaging probes. Specifically, it could achieve synergetic therapeutic effects, demonstrating stronger killing effects to MDR cancer cells by combining the inorganic nanocarriers with other treatment manners, such as RNA interference and thermal therapy. Moreover, the inorganic nanocarriers could provide imaging functions to help monitor treatment responses, e.g., drug resistance and therapeutic effects, as well as analyze the mechanism of MDR by molecular imaging modalities. In this review, the mechanisms involved in cancer MDR and recent advances of applying inorganic nanocarriers for MDR cancer imaging and therapy are summarized. The inorganic nanocarriers may circumvent cancer MDR for effective therapy and provide a way to track the therapeutic processes for real-time molecular imaging, demonstrating high performance in studying the interaction of nanocarriers and MDR cancer cells/tissues in laboratory study and further shedding light on elaborate design of nanocarriers that could overcome MDR for clinical translation.

Tf-PEG-PLL-PLGA nanoparticles enhanced chemosensitivity for hypoxia-responsive tumor cells

Hypoxia is an inseparable component of the solid tumor as well as the bone marrow microenvironment. In this study, we investigated the effect of the novel polyethylene glycol (PEG)-poly L-lysine (PLL)-poly lactic-co-glycolic acid (PLGA) based nanoparticles (NPs) modified by transferrin (Tf) loaded with daunorubicin (DNR) (DNR-Tf-PEG-PLL-PLGA-NPs, abbreviated as DNR-Tf-NPs) on leukemia cells (K562) under hypoxia. In vitro and in vivo tests to determine the effect of the enhanced chemosensitivity were evaluated using the immunofluorescence, flow cytometry, 3,-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-tetrazoliumbromide assay, Western blot analysis, histopathological examination, and immunohistochemistry analysis. Under hypoxia, K562 cells were hypoxia-responsive with the inhibitory concentration 50% (IC50) of DNR increased, resulting in chemotherapy insensitivity. By targeting the transferrin receptor (TfR) on the surface of K562 cells, DNR-Tf-NPs led to an increased intracellular DNR level, enhancing drug sensitivity of K562 cells to DNR with a decreased IC50, even under hypoxia. We further detected the protein levels of hypoxia-inducible factor-1α (HIF-1α), Bcl-2, Bax, and caspase-3 in K562 cells. The results indicated that DNR-Tf-NPs downregulated HIF-1α and induced apoptosis to overcome hypoxia. In the xenograft model, injection of DNR-Tf-NPs significantly suppressed tumor growth, and the immunosignals of Ki67 in DNR-Tf-NPs group was significantly lower than the other groups. It was therefore concluded that DNR-Tf-NPs could be a promising candidate for enhancing drug sensitivity under hypoxia in tumor treatment.

Assessing Therapeutic Potential of Magnetic Mesoporous Nanoassemblies for Chemo-Resistant Tumors

Smart drug delivery system with strategic drug distribution is the future state-of-the-art treatment for any malignancy. To investigate therapeutic potential of such nanoparticle mediated delivery system, we examined the efficacy of dual drug-loaded, pH and thermo liable lipid coated mesoporous iron oxide-based magnetic nanoassemblies (DOX:TXL-LMMNA) in mice bearing both drug sensitive (A2780(S)) and drug resistant (A2780-CisR) ovarian cancer tumor xenografts. In presence of an external AC magnetic field (ACMF), DOX:TXL-LMMNA particles disintegrate to release encapsulated drug due to hyperthermic temperatures (41-45 ºC). In vivo bio distribution study utilizing the optical and magnetic properties of DOX:TXL-LMMNA particles demonstrated minimum organ specific toxicity. Noninvasive bioluminescence imaging of mice bearing A2780(S) tumors and administered with DOX-TXL-LMMNA followed by the application of ACMF revealed 65% less luminescence signal and 80% mice showed complete tumor regression within eight days. A six months follow-up study revealed absence of relapse in 70% of the mice. Interestingly, the A2780-CisR tumors which did not respond to drug alone (DOX:TXL) showed 80% reduction in luminescence and tumor volume with DOX:TXL-LMMNA after thermo-chemotherapy within eight days. Cytotoxic effect of DOX:TXL-LMMNA particles was more pronounced in A2780-CisR cells than in their sensitive counterpart. Thus these novel stimuli sensitive nanoassemblies hold great promise for therapy resistant malignancies and future clinical applications.

Magnetic Fluorescent Nanoformulation for Intracellular Drug Delivery to Human Breast Cancer, Primary Tumors, and Tumor Biopsies: Beyond Targeting Expectations

We report the development of a chemotherapeutic nanoformulation made of polyvinylpyrrolidone-stabilized magnetofluorescent nanoparticles (Fl-PMNPs) loaded with anticancer drugs as a promising drug carrier homing to human breast cancer cells, primary tumors, and solid tumors. First, nanoparticle uptake and cell death were evaluated in three types of human breast cells: two metastatic cancerous MCF-7 and MDA-MB-231 cells and nontumorigenic MCF-10A cells. While Fl-PMNPs were not toxic to cells even at the highest concentrations used, Dox-loaded Fl-PMNPs showed significant potency, effectively killing the different breast cancer cells, albeit at different affinities. Interestingly and superior to free Dox, Dox-loaded Fl-PMNPs were found to be more effective in killing the metastatic cells (2- to 3-fold enhanced cytotoxicities for MDA-MB-231 compared to MCF-7), compared to the normal noncancerous MCF-10A cells (up to 8-fold), suggesting huge potentials as selective anticancer agents. Electron and live confocal microscopy imaging mechanistically confirmed that the nanoparticles were successfully endocytosed and packaged into vesicles inside the cytoplasm, where Dox is released and then translocated to the nucleus exerting its cytotoxic action and causing apoptotic cell death. Furthermore, commendable and enhanced penetration in 3D multilayered primary tumor cells derived from primary lesions as well as in patient breast tumor biopsies was observed, killing the tumor cells inside. The designed nanocarriers described here can potentially open new opportunities for breast cancer patients, especially in theranostic imaging and hyperthermia. While many prior studies have focused on targeting ligands to specific receptors to improve efficacies, we discovered that even with passive-targeted tailored delivery system enhanced toxic responses can be attained.

Preparation of magnetic mesoporous silica nanoparticles as a multifunctional platform for potential drug delivery and hyperthermia

We report the preparation of magnetic mesoporous silica (MMS) nanoparticles with the potential multifunctionality of drug delivery and magnetic hyperthermia. Carbon-encapsulated magnetic colloidal nanoparticles (MCN@C) were used to coat mesoporous silica shells for the formation of the core-shell structured MMS nanoparticles (MCN@C/mSiO₂), and the rattle-type structured MMS nanoparticles (MCN/mSiO₂) were obtained after the removal of the carbon layers from MCN@C/mSiO₂ nanoparticles. The morphology, structure, magnetic hyperthermia ability, drug release behavior, in vitro cytotoxicity and cellular uptake of MMS nanoparticles were investigated. The results revealed that the MCN@C/mSiO₂ and MCN/mSiO₂ nanoparticles had spherical morphology and average particle sizes of 390 and 320 nm, respectively. The MCN@C/mSiO₂ nanoparticles exhibited higher magnetic hyperthermia ability compared to the MCN/mSiO₂ nanoparticles, but the MCN/mSiO₂ nanoparticles had higher drug loading capacity. Both MCN@C/mSiO₂ and MCN/mSiO₂ nanoparticles had similar drug release behavior with pH-controlled release and temperature-accelerated release. Furthermore, the MCN@C/mSiO₂ and MCN/mSiO₂ nanoparticles showed low cytotoxicity and could be internalized into HeLa cells. Therefore, the MCN@C/mSiO₂ and MCN/mSiO₂ nanoparticles would be promising for the combination of drug delivery and magnetic hyperthermia treatment in cancer therapy.

A Tumor-specific MicroRNA Recognition System Facilitates the Accurate Targeting to Tumor Cells by Magnetic Nanoparticles

Targeted therapy for cancer is a research area of great interest, and magnetic nanoparticles (MNPs) show great potential as targeted carriers for therapeutics. One important class of cancer biomarkers is microRNAs (miRNAs), which play a significant role in tumor initiation and progression. In this study, a cascade recognition system containing multiple plasmids, including a Tet activator, a lacI repressor gene driven by the TetOn promoter, and a reporter gene repressed by the lacI repressor and influenced by multiple endogenous miRNAs, was used to recognize cells that display miRNA signals that are characteristic of cancer. For this purpose, three types of signal miRNAs with high proliferation and metastasis abilities were chosen (miR-21, miR-145, and miR-9). The response of this system to the human breast cancer MCF-7 cell line was 3.2-fold higher than that to the human breast epithelial HBL100 cell line and almost 7.5-fold higher than that to human embryonic kidney HEK293T cells. In combination with polyethyleneimine-modified MNPs, this recognition system targeted the tumor location in situ in an animal model, and an ~42% repression of tumor growth was achieved. Our study provides a new combination of magnetic nanocarrier and gene therapy based on miRNAs that are active in vivo, which has potential for use in future cancer therapies.

Comparison of the interactions of daunorubicin in a free form and attached to single-walled carbon nanotubes with model lipid membranes

In this work the interactions of an anticancer drug daunorubicin (DNR) with model thiolipid layers composed of 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol (DPPTE) were investigated using Langmuir technique. The results obtained for a free drug were compared with the results recorded for DNR attached to SWCNTs as potential drug carrier. Langmuir studies of mixed DPPTE-SWCNTs-DNR monolayers showed that even at the highest investigated content of the nanotubes in the monolayer, the changes in the properties of DPPTE model membranes were not as significant as in case of the incorporation of a free drug, which resulted in a significant increase in the area per molecule and fluidization of the thiolipid layer. The presence of SWCNTs-DNR in the DPPTE monolayer at the air-water interface did not change the organization of the lipid molecules to such extent as the free drug, which may be explained by different types of interactions playing crucial role in these two types of systems. In the case of the interactions of free DNR the electrostatic attraction between positively charged drug and negatively charged DPPTE monolayer play the most important role, while in the case of SWCNTs-DNR adducts the hydrophobic interactions between nanotubes and acyl chains of the lipid seem to be prevailing. Electrochemical studies performed for supported model membranes containing the drug delivered in the two investigated forms revealed that the surface concentration of the drug-nanotube adduct in supported monolayers is comparable to the reported surface concentration of the free DNR incorporated into DPPTE monolayers on gold electrodes. Therefore, it may be concluded that the application of carbon nanotubes as potential DNR carrier allows for the incorporation of comparable amount of the drug into model membranes with simultaneous decrease in the negative changes in the membrane structure and organization, which is an important aspect in terms of side effects of the drug.

Hybrid Nanomaterials Based on Iron Oxide Nanoparticles and Mesoporous Silica Nanoparticles: Overcoming Challenges in Current Cancer Treatments

The current approaches used for the treatment of cancer face some clinical limitations such as induction of severe side effects, multidrug resistance (MDR), and low specificity toward metastatic cancer cells. Hybrid nanomaterials hold a great potential to overcome all these challenges. Among hybrid nanoparticles, those based on mesoporous silica and iron oxide nanoparticles (MSNs and IONPs) have gained a privileged place in the biomedical field because of their outstanding properties. There are many studies demonstrating their effectiveness as drug delivery systems, nanoheaters, and imaging contrast agents. This review summarizes the advances related to the utilization of IONPs and MSNs for reducing side effects, overcoming MDR, and inhibiting metastasis. Furthermore, we give a future perspective of the clinical application of these technologies.

Hybrid nanoparticles for combination therapy of cancer

Nanoparticle anticancer drug delivery enhances therapeutic efficacies and reduces side effects by improving pharmacokinetics and biodistributions of the drug payloads in animal models. Despite promising preclinical efficacy results, monotherapy nanomedicines have failed to produce enhanced response rates over conventional chemotherapy in human clinical trials. The discrepancy between preclinical data and clinical outcomes is believed to result from the less pronounced enhanced permeability and retention (EPR) effect in and the heterogeneity of human tumors as well as the intrinsic/acquired drug resistance to monotherapy over the treatment course. To address these issues, recent efforts have been devoted to developing nanocarriers that can efficiently deliver multiple therapeutics with controlled release properties and increased tumor deposition. In ideal scenarios, the drug or therapeutic modality combinations have different mechanisms of action to afford synergistic effects. In this review, we summarize recent progress in designing hybrid nanoparticles for the co-delivery of combination therapies, including multiple chemotherapeutics, chemotherapeutics and biologics, chemotherapeutics and photodynamic therapy, and chemotherapeutics and radiotherapy. The in vitro and in vivo anticancer effects are also discussed.

Combination of PEI-Mn0.5Zn0.5Fe2O4 nanoparticles and pHsp 70-HSV-TK/GCV with magnet-induced heating for treatment of hepatoma

Background

To explore a new combination of thermal treatment and gene therapy for hepatoma, a heat-inducible herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy system was developed in which thermal energy generated by Mn_0.5Zn_0.5Fe₂O₄ nanoparticles (MZF-NPs) under an alternating magnetic field was used to activate gene expression.

Methods

First, a recombinant eukaryotic plasmid, pHsp 70-HSV-TK, was constructed as a target gene for therapy. This recombinant plasmid was used to transfect SMMC-7721 hepatoma cells and the gene expression was evaluated. Magnet-induced heating was then applied to cells to assess the antihepatoma effects of the polyethylenimine (PEI)-MZF-NPs/pHsp 70-HSV-TK/GCV complex, in vitro and in vivo.

Results

The results showed that cells were successfully transfected with pHsp 70-HSV-TK and that expression levels of HSV-TK remained stable. Both in vitro and in vivo results indicated that the combination of gene therapy and heat treatment resulted in better therapeutic effects than heating-alone group. The rates of apoptosis and necrosis in the combined treatment group were 49.0% and 7.21%, respectively. The rate of inhibition of cell proliferation in the combined treatment group was significantly higher (87.5%) than that in the heating-alone group (65.8%; P<0.01). The tumor volume and mass inhibition rates of the combined treatment group were 91.3% and 87.91%, respectively, and were significantly higher than the corresponding rates of the heating-alone group (70.41% and 57.14%; P<0.01). The expression levels of Stat3 and Bcl-xL messenger RNA and p-Stat3 and Bcl-xL protein in the combined treatment group were significantly lower than those in the other groups (P<0.01). The expression levels of Bax messenger RNA and protein in the recombinant plasmid group were significantly higher than those in the other groups (P<0.01).

Conclusion

It can therefore be concluded that the combined application of heat treatment and gene therapy has a synergistic and complementary effect and that PEI-MZF-NPs can simultaneously act both as a nonviral gene vector and a magnet-induced source of heat, thereby representing a viable approach for the treatment of cancer.

Targeted multidrug-resistance reversal in tumor based on PEG-PLL-PLGA polymer nano drug delivery system

The study investigated the reversal of multidrug resistance (MDR) and the biodistribution of nanoparticles (NPs) that target leukemia cells in a nude mice model via a surface-bound transferrin (Tf). The cytotoxic cargo of daunorubicin (DNR) and tetrandrine (Tet) was protected in the NPs by an outer coat composed of polyethylene glycol (PEG)-poly-l-lysine (PLL)-poly(lactic-co-glycolic acid) (PLGA) NPs. Injection of DNR-Tet-Tf-PEG-PLL-PLGA NPs into nude mice bearing MDR leukemia cell K562/A02 xenografts was shown to inhibit tumor growth, and contemporaneous immunohistochemical analysis of tumor tissue showed the targeted NPs induced apoptosis in tumor cells. Targeted tumor cells exhibited a marked increase in Tf receptor expression, with noticeable decreases in P-glycoprotein, MDR protein, and nuclear factor κB, as assessed by quantitative real-time polymerase chain reaction and Western blot analysis. Moreover, the concentration of DNR was shown to increase in plasma, tumor tissue, and major organs. Flow cytometry analysis with a near-infrared fluorescent (NIRF) dye, NIR797, was used to study the effectiveness of Tf as a targeting group for leukemia cells, a finding that was supported by NIRF imaging in tumor-bearing nude mice. In summary, our studies show that DNR-Tet-Tf-PEG-PLL-PLGA NPs provide a specific and effective means to target cytotoxic drugs to MDR tumor cells.

Nanotechnology applications in hematological malignancies (Review)

A major limitation to current cancer therapies is the development of therapy-related side-effects and dose limiting complications. Moreover, a better understanding of the biology of cancer cells and the mechanisms of resistance to therapy is rapidly developing. The translation of advanced knowledge and discoveries achieved at the molecular level must be supported by advanced diagnostic, therapeutic and delivery technologies to translate these discoveries into useful tools that are essential in achieving progress in the war against cancer. Nanotechnology can play an essential role in this aspect providing a transforming technology that can translate the basic and clinical findings into novel diagnostic, therapeutic and preventive tools useful in different types of cancer. Hematological malignancies represent a specific class of cancer, which attracts special attention in the applications of nanotechnology for cancer diagnosis and treatment. The aim of the present review is to elucidate the emerging applications of nanotechnology in cancer management and describe the potentials of nanotechnology in changing the key fundamental aspects of hematological malignancy diagnosis, treatment and follow-up.

Magnetic thermoablation stimuli alter BCL2 and FGF-R1 but not HSP70 expression profiles in BT474 breast tumors

Magnetically induced heating of magnetic nanoparticles (MNP) in an alternating magnetic field (AMF) is a promising minimal invasive tool for localized tumor treatment that eradicates tumor cells by applying thermal stress. While temperatures between 42°C and 45°C induce apoptosis and sensitize the cells for chemo- and radiation therapies when applied for at least 30 minutes, temperatures above 50°C, so-called thermoablative temperatures, rapidly induce irreversible cell damage resulting in necrosis. Since only little is known concerning the protein expression of anti-apoptotic B-cell lymphoma 2 (BCL2), fibroblast growth factor receptor 1 (FGF-R1), and heat shock protein (HSP70) after short-time magnetic thermoablative tumor treatment, these relevant tumor proteins were investigated by immunohistochemistry (IHC) in a human BT474 breast cancer mouse xenograft model. In the investigated sample groups, the application of thermoablative temperatures (<2 minutes) led to a downregulation of BCL2 and FGF-R1 on the protein level while the level of HSP70 remained unchanged. Coincidently, the tumor tissue was damaged by heat, resulting in large apoptotic and necrotic areas in regions with high MNP concentration. Taken together, thermoablative heating induced via magnetic methods can reduce the expression of tumor-related proteins and locally inactivate tumor tissue, leading to a prospectively reduced tumorigenicity of cancerous tissues. The presented data allow a deeper insight into the molecular mechanisms in relation to magnetic thermoablative tumor treatments with the aim of further improvements.

The antitumor activity of tumor-homing peptide-modified thermosensitive liposomes containing doxorubicin on MCF-7/ADR: in vitro and in vivo

Clotted plasma proteins are present on the walls of tumor vessels and in tumor stroma. Tumor-homing peptide Cys-Arg-Glu-Lys-Ala (CREKA) could recognize the clotted plasma proteins in tumor vessels. Thermosensitive liposomes could immediately release the encapsulated drug in the vasculature of the heated tumor. In this study, we designed a novel form of targeted thermosensitive liposomes, CREKA-modified lysolipid-containing thermosensitive liposomes (LTSLs), containing doxorubicin (DOX) (DOX-LTSL-CREKA), to investigate the hypothesis that DOX-LTSL-CREKA might target the clotted plasma proteins in tumor vessels as well as tumor stroma and then exhibit burst release of the encapsulated DOX at the heated tumor site. We also hypothesized that the high local drug concentration produced by these thermosensitive liposomes after local hyperthermia treatment will be useful for treatment of multidrug resistance. The multidrug-resistant human breast adenocarcinoma (MCF-7/ADR) cell line was chosen as a tumor cell model, and the targeting and immediate release characteristics of DOX-LTSL-CREKA were investigated in vitro and in vivo. Furthermore, the antitumor activity of DOX-LTSL-CREKA was evaluated in MCF-7/ADR tumor-bearing nude mice in vivo. The targeting effect of the CREKA-modified thermosensitive liposomes on the clotted plasma proteins was confirmed in our in vivo imaging and immunohistochemistry experiments. The burst release of this delivery system was observed in our in vitro temperature-triggered DOX release and flow cytometry analysis and also by confocal microscopy experiments. The antitumor activity of the DOX-LTSL-CREKA was confirmed in tumor-bearing nude mice in vivo. Our findings suggest that the combination of targeting the clotted plasma proteins in the tumor vessel wall as well as tumor stroma by using CREKA peptide and temperature-triggered drug release from liposomes by using thermosensitive liposomes offers an attractive strategy for chemotherapeutic drug delivery to tumors.

Synthesis, characterization and in vitro study of biocompatible cinnamaldehyde functionalized magnetite nanoparticles (CPGF Nps) for hyperthermia and drug delivery applications in breast cancer

Cinnamaldehyde, the bioactive component of the spice cinnamon, and its derivatives have been shown to possess anti-cancer activity against various cancer cell lines. However, its hydrophobic nature invites attention for efficient drug delivery systems that would enhance the bioavailability of cinnamaldehyde without affecting its bioactivity. Here, we report the synthesis of stable aqueous suspension of cinnamaldehyde tagged Fe3O4 nanoparticles capped with glycine and pluronic polymer (CPGF NPs) for their potential application in drug delivery and hyperthermia in breast cancer. The monodispersed superparamagnetic NPs had an average particulate size of ∼ 20 nm. TGA data revealed the drug payload of ∼ 18%. Compared to the free cinnamaldehyde, CPGF NPs reduced the viability of breast cancer cell lines, MCF7 and MDAMB231, at lower doses of cinnamaldehyde suggesting its increased bioavailability and in turn its therapeutic efficacy in the cells. Interestingly, the NPs were non-toxic to the non-cancerous HEK293 and MCF10A cell lines compared to the free cinnamaldehyde. The novelty of CPGF nanoparticulate system was that it could induce cytotoxicity in both ER/PR positive/Her2 negative (MCF7) and ER/PR negative/Her2 negative (MDAMB231) breast cancer cells, the latter being insensitive to most of the chemotherapeutic drugs. The NPs decreased the growth of the breast cancer cells in a dose-dependent manner and altered their migration through reduction in MMP-2 expression. CPGF NPs also decreased the expression of VEGF, an important oncomarker of tumor angiogenesis. They induced apoptosis in breast cancer cells through loss of mitochondrial membrane potential and activation of caspase-3. Interestingly, upon exposure to the radiofrequency waves, the NPs heated up to 41.6 °C within 1 min, suggesting their promise as a magnetic hyperthermia agent. All these findings indicate that CPGF NPs prove to be potential nano-chemotherapeutic agents in breast cancer.

Tumor targeting using magnetic nanoparticle Hsp70 conjugate in a model of C6 glioma

BACKGROUND

Superparamagnetic iron oxide nanoparticles (SPIONs), due to their unique magnetic properties, have the ability to function both as magnetic resonance (MR) contrast agents, and can be used for thermotherapy. SPIONs conjugated to the heat shock protein Hsp70 that selectively binds to the CD40 receptor present on glioma cells, could be used for MR contrast enhancement of experimental C6 glioma.

METHODS

The magnetic properties of the Hsp70-SPIONs were measured by NMR relaxometry method. The uptake of nanoparticles was assessed on the C6 glioma cells by confocal and electron microscopes. The tumor selectivity of Hsp70-SPIONs being intravenously administered was analyzed in the experimental model of C6 glioma in the MRI scanner.

RESULTS

Hsp70-SPIONs relaxivity corresponded to the properties of negative contrast agents with a hypointensive change of resonance signal in MR imaging. A significant accumulation of the Hsp70-SPIONs but not the non-conjugated nanoparticles was observed by confocal microscopy within C6 cells. Negative contrast tumor enhancement in the T2-weighted MR images was higher in the case of Hsp70-SPIONs in comparison to non-modified SPIONs. Histological analysis of the brain sections confirmed the retention of the Hsp70-SPIONs in the glioma tumor but not in the adjacent normal brain tissues.

CONCLUSION

The study demonstrated that Hsp70-SPION conjugate intravenously administered in C6 glioma model accumulated in the tumors and enhanced the contrast of their MR images.

Thermal potentiation of chemotherapy by magnetic nanoparticles

Clinical studies have demonstrated the effectiveness of hyperthermia as an adjuvant for chemotherapy and radiotherapy. However, significant clinical challenges have been encountered, such as a broader spectrum of toxicity, lack of patient tolerance, temperature control and significant invasiveness. Hyperthermia induced by magnetic nanoparticles in high-frequency oscillating magnetic fields, commonly termed magnetic fluid hyperthermia, is a promising form of heat delivery in which thermal energy is supplied at the nanoscale to the tumor. This review discusses the mechanisms of heat dissipation of iron oxide-based magnetic nanoparticles, current methods and challenges to deliver heat in the clinic, and the current work related to the use of magnetic nanoparticles for the thermal-chemopotentiation of therapeutic drugs.

Magnetic nanoparticles of Fe3O4 enhance docetaxel-induced prostate cancer cell death

Docetaxel (DTX) is one of the most important anticancer drugs; however, the severity of its adverse effects detracts from its practical use in the clinic. Magnetic nanoparticles of Fe₃O₄ (MgNPs-Fe₃O₄) can enhance the delivery and efficacy of anticancer drugs. We investigated the effects of MgNPs-Fe₃O₄ or DTX alone, and in combination with prostate cancer cell growth in vitro, as well as with the mechanism underlying the cytotoxic effects. MgNPs-Fe₃O₄ caused dose-dependent increases in reactive oxygen species levels in DU145, PC-3, and LNCaP cells; 8-hydroxydeoxyguanosine levels were also elevated. MgNPs-Fe₃O₄ alone reduced the viability of LNCaP and PC-3 cells; however, MgNPs-Fe₃O₄ enhanced the cytotoxic effect of a low dose of DTX in all three cell lines. MgNPs-Fe₃O₄ also augmented the percentage of DU145 cells undergoing apoptosis following treatment with low dose DTX. Expression of nuclear transcription factor κB in DU145 was not affected by MgNPs-Fe₃O₄ or DTX alone; however, combined treatment suppressed nuclear transcription factor κB expression. These findings offer the possibility that MgNPs-Fe₃O₄–low dose DTX combination therapy may be effective in treating prostate cancer with limited adverse effects.

Intravenous magnetic nanoparticle cancer hyperthermia

Magnetic nanoparticles heated by an alternating magnetic field could be used to treat cancers, either alone or in combination with radiotherapy or chemotherapy. However, direct intratumoral injections suffer from tumor incongruence and invasiveness, typically leaving undertreated regions, which lead to cancer regrowth. Intravenous injection more faithfully loads tumors, but, so far, it has been difficult achieving the necessary concentration in tumors before systemic toxicity occurs. Here, we describe use of a magnetic nanoparticle that, with a well-tolerated intravenous dose, achieved a tumor concentration of 1.9 mg Fe/g tumor in a subcutaneous squamous cell carcinoma mouse model, with a tumor to non-tumor ratio > 16. With an applied field of 38 kA/m at 980 kHz, tumors could be heated to 60°C in 2 minutes, durably ablating them with millimeter (mm) precision, leaving surrounding tissue intact.

Paclitaxel-Fe3O4 nanoparticles inhibit growth of CD138(-) CD34(-) tumor stem-like cells in multiple myeloma-bearing mice

BACKGROUND

There is growing evidence that CD138(-) CD34(-) cells may actually be tumor stem cells responsible for initiation and relapse of multiple myeloma. However, effective drugs targeted at CD138(-) CD34(-) tumor stem cells are yet to be developed. The purpose of this study was to investigate the inhibitory effect of paclitaxel-loaded Fe3O4 nanoparticles (PTX-NPs) on CD138(-) CD34(-) tumor stem cells in multiple myeloma-bearing mice.

METHODS

CD138(-) CD34(-) cells were isolated from a human U266 multiple myeloma cell line using an immune magnetic bead sorting method and then subcutaneously injected into mice with nonobese diabetic/severe combined immunodeficiency to develop a multiple myeloma-bearing mouse model. The mice were treated with Fe3O4 nanoparticles 2 mg/kg, paclitaxel 4.8 mg/kg, and PTX-NPs 0.64 mg/kg for 2 weeks. Tumor growth, pathological changes, serum and urinary interleukin-6 levels, and molecular expression of caspase-3, caspase-8, and caspase-9 were evaluated.

RESULTS

CD138(-) CD34(-) cells were found to have tumor stem cell characteristics. All the mice developed tumors in 40 days after injection of 1 × 10(6) CD138(-) CD34(-) tumor stem cells. Tumor growth in mice treated with PTX-NPs was significantly inhibited compared with the controls (P < 0.005), and the groups that received nanoparticles alone (P < 0.005) or paclitaxel alone (P < 0.05). In addition, the PTX-NPs markedly inhibited interleukin-6 secretion, increased caspase-8, caspase-9, and caspase-3 expression, and induced apoptosis of tumor cells in the treated mice.

CONCLUSION

PTX-NPs proved to be a potent anticancer treatment strategy that may contribute to targeted therapy for multiple myeloma tumor stem cells in future clinical trials.