Free Mitomycin C Research Articles

Treating colorectal peritoneal metastases with an injectable cytostatic loaded supramolecular hydrogel in a rodent animal model

Patients with peritoneal metastases (PM) of colorectal cancer have a very poor outcome. Intraperitoneal delivery of chemotherapy is the preferred route for PM treatment. The main limitation of the treatment options is the short residence time of the cytostatic, with subsequent short exposure of the cancer cells. To address this, a supramolecular hydrogel has been developed that allows both local and slow release of its encapsulated drug, mitomycin C (MMC) or cholesterol-conjugated MMC (cMMC), respectively. This experimental study investigates if drug delivery using this hydrogel improves the therapeutic efficacy against PM. PM was induced in WAG/Rij rats (n = 72) by intraperitoneally injecting syngeneic colon carcinoma cells (CC531) expressing luciferase. After seven days, animals received a single intraperitoneal injection with saline (n = 8), unloaded hydrogel (n = 12), free MMC (n = 13), free cMMC (n = 13), MMC-loaded hydrogel (n = 13), or cMMC-loaded hydrogel (n = 13). Primary outcome was overall survival with a maximum follow-up of 120 days. Intraperitoneal tumor development was non-invasive monitored via bioluminescence imaging. Sixty-one rats successfully underwent all study procedures and were included to assess therapeutic efficacy. After 120 days, the overall survival in the MMC-loaded hydrogel and free MMC group was 78% and 38%, respectively. A trend toward significance was found when comparing the survival curves of the MMC-loaded hydrogel and free MMC (p = 0.087). No survival benefit was found for the cMMC-loaded hydrogel compared to free cMMC. Treating PM with our MMC-loaded hydrogel, exhibiting prolonged MMC exposure, seems effective in improving survival compared to treatment with free MMC.

Functionalized Mesoporous Silica Nanoparticles for Drug-Delivery to Multidrug-Resistant Cancer Cells

BackgroundMultidrug resistance is a common reason behind the failure of chemotherapy. Even if the therapy is effective, serious adverse effects might develop due to the low specificity and selectivity of antineoplastic agents. Mesoporous silica nanoparticles (MSNs) are promising materials for tumor-targeting and drug-delivery due to their small size, relatively inert nature, and extremely large specific surfaces that can be functionalized by therapeutic and targeting entities. We aimed to create a fluorescently labeled MSN-based drug-delivery system and investigate their internalization and drug-releasing capability in drug-sensitive MCF-7 and P-glycoprotein-overexpressing multidrug-resistant MCF-7 KCR cancer cells.Methods and ResultsTo track the uptake and subcellular distribution of MSNs, particles with covalently coupled red fluorescent Rhodamine B (RhoB) were produced (RhoB@MSNs). Both MCF-7 and MCF-7 KCR cells accumulated a significant amount of RhoB@MSNs. The intracellular RhoB@MSN concentrations did not differ between sensitive and multidrug-resistant cells and were kept at the same level even after cessation of RhoB@MSN exposure. Although most RhoB@MSNs resided in the cytoplasm, significantly more RhoB@MSNs co-localized with lysosomes in multidrug-resistant cells compared to sensitive counterparts. To examine the drug-delivery capability of these particles, RhoB@Rho123@MSNs were established, where RhoB-functionalized nanoparticles carried green fluorescent Rhodamine 123 (Rho123) - a P-glycoprotein substrate – as cargo within mesopores. Significantly higher Rho123 fluorescence intensity was detected in RhoB@Rho123@MSN-treated multidrug-resistant cells than in free Rho123-exposed counterparts. The exceptional drug-delivery potential of MSNs was further verified using Mitomycin C (MMC)-loaded RhoB@MSNs (RhoB@MMC@MSNs). Exposures to RhoB@MMC@MSNs significantly decreased the viability not only of drug-sensitive but of multidrug-resistant cells and the elimination of MDR cells was significantly more robust than upon free MMC treatments.ConclusionThe efficient delivery of Rho123 and MMC to multidrug-resistant cells via MSNs, the amplified and presumably prolonged intracellular drug concentration, and the consequently enhanced cytotoxic effects envision the enormous potential of MSNs to defeat multidrug-resistant cancer.

Antitumor Activity of a Novel Double-Targeted System for Folate Receptor-Mediated Delivery of Mitomycin C.

In this study, we designed, formulated, and investigated the potential antitumor activity of a folate receptor (FR)-mediated double-targeted drug delivery system. The system comprised of the FR ligand folic acid (FA), glycine-phenylalanine-leucine-glycine (Gly-Phe-Leu-Gly, GFLG), which can be specifically cleaved by cathepsin B, and the anticancer drug mitomycin C (MMC). The antitumor effect of FA-GFLG-MMC was compared to that of MMC. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay revealed that FA-GFLG-MMC has a significantly higher inhibitory effect on HeLa, SiHa, and PC9 cells (high FR expression) than that on 16HBE and A549 cells (low FR expression). Furthermore, FA-GFLG-MMC inhibited cancer cell proliferation in a dose-dependent manner. Free MMC was toxic to both cancer and normal cells. Apoptosis of the HeLa, SiHa, and PC9 cells was higher than that of the A549 cells; however, the apoptotic effect on 16HBE cells was minimal. Proapoptotic protein bcl-2-associated X-protein (BAX) and antiapoptotic protein BCL-2 play critical roles in cellular defense and apoptotic signal transduction. BAX/BCL-2 ratio is used to determine the intensity of an apoptotic signal and assess whether a cell will survive or undergo apoptosis. BAX and BCL-2 expression in cells treated with 5 μM FA-GFLG-MMC was studied by Western blotting. FA-GFLG-MMC increased the BAX/BCL-2 ratio in HeLa, SiHa, and PC9 cells. The results show that FA-GFLG-MMC can effectively inhibit tumor cell proliferation by inducing apoptosis. Therefore, the system developed can enhance the delivery of anticancer drugs to cancer cells and thereby reduce their toxic effects on normal cells.

LHRH Targeted Chonderosomes of Mitomycin C in Breast Cancer: An In Vitro/ In Vivo Study.

Mitomycin C (MMC) is an anti-cancer drug used for the treatment of breast cancer with limited therapeutic index, extreme gastric adverse effects and bone marrow suppression. The purpose of the present study was the preparation of a dual-targeted delivery system of MMC for targeting CD44 and LHRH overexpressed receptors of breast cancer. MMC loaded LHRH targeted chonderosome was prepared by precipitation method and was characterized for their physicochemical properties. Cell cycle arrest and cytotoxicity tests were studied on cell lines of MCF-7, MDA-MB231 and 4T1 (as CD44 and LHRH positive cells) and BT-474 cell line (as CD44 negative receptor cells). The in vivo histopathology and antitumor activity of MMC-loaded chonderosomes were compared with free MMC in 4T1 cells inducing breast cancer in Balb-c mice. MMC loaded LHRH targeted chonderosomes caused 3.3 and 5.5 fold more cytotoxicity on MCF-7 and 4T1 cells than free MMC at concentrations of 100μM and 10μM, respectively. However, on BT-474 cells the difference was insignificant. The cell cycle test showed no change for MMC mechanism of action when it was loaded in chonderosomes compared to free MMC. The in vivo antitumor studies showed that MMC loaded LHRH targeted chonderosomes were 6.5 fold more effective in the reduction of tumor volume than free MMC with the most severe necrosis compared to non-targeted chonderosomes in pathological studies on harvested tumors. The developed MMC loaded LHRH targeted chonderosomes were more effective in tumor growth suppression and may be promising for targeted delivery of MMC in breast cancer.

Cytotoxicity and apoptosis enhancement in breast and cervical cancer cells upon coadministration of mitomycin C and essential oils in nanoemulsion formulations

The present study aimed to solubilize the antineoplastic agent, mitomycin C (MMC), in two nanoemulsions (NEs) consisting of different essential oils (ginger (Gi) and frankincense (Fr)) in order to examine their anticancer activities on the HeLa cervical cancer cells and MCF-7 breast cancer cells. The two NEs-based Gi and Fr oil were produced by a high-pressure homogenization technique followed by solubilizing of the MMC in both NE formulas. The produced formulas were physically characterized by zetasizer and were applied on HeLa and MCF-7 cells at various concentrations for 24 h. The cytotoxicity assays were performed in vitro, using MTT assay, Coomassie blue staining for cellular morphology evaluation, and DAPI fluorescent staining for molecular cell death assessment. The average droplet diameters of the blank NEs have markedly increased and the charges of the droplets were significantly reversed when MMC was loaded. The potential cytotoxicity of the blank and combined formulas on HeLa and MCF-7 cells were dose-dependent and significantly greater than the toxicities of the free MMC. Among the MMC-loaded NE formulas, Fr-MMC has endured the nuclear apoptosis in HeLa cells at a lower concentration and reported the least % of florescence uptake compared to Gi-MMC. In contrast, the combination formula, Gi-MMC, has the strongest apoptotic effect on the MCF-7 cell line since it has the least % florescence uptake compared to the other formulations. Mixing MMC with Gi-NE and Fr-NE has considerably improved its cytotoxicity on the MCF-7 and HeLa cells.

A new drug delivery system for Mitomycin C to improve intravesical instillation

The conventional administration of Mitomycin C (MMC) in intravesical instillations has its limitations. In this study, MMC was loaded onto an in situ forming depot consisting of chitosan (CS), β-glycerophosphate (GP) and Fe3O4 magnetic nanoparticles (Fe3O4-MNPs) to improve its effects. The features and effects of this new drug delivery mode were investigated. The new drug delivery system (Fe3O4-MMC-CS/GP) exhibited superior sol-gel transformation and magnetism. Sustained release of MMC was observed both in vitro and in vivo, and the retention, which lasted for 72h in the rat bladder, was further examined using frozen sections. The Cell-Counting Kit-8 (CCK-8) and flow cytometry assays revealed better anti-tumor activity of Fe3O4-MMC-CS/GP compared with the free MMC solution. Animal experiments showed that Fe3O4-MMC-CS/GP provided a favorable survival rate and inhibited the growth of bladder tumors. Moreover, this drug delivery system enhanced tumor cell apoptosis compared with the conventional route of MMC administration in rats.

Preclinical Evaluation of Promitil, a Radiation-Responsive Liposomal Formulation of Mitomycin C Prodrug, in Chemoradiotherapy

Toexamine the effect of radiation on invitro drug activation and release of Promitil, apegylated liposomal formulation of a mitomycin C (MMC) lipid-based prodrug; and examine the efficacy and toxicity of Promitil with concurrent radiation in colorectal cancer models. Promitil was obtained from Lipomedix Pharmaceuticals (Jerusalem, Israel). We tested the effects of radiation on release of active MMC from Promitil invitro. We next examined the radiosensitization effect of Promitil invitro. We further evaluated the toxicity of a single injection of free MMC or Promitil when combined with radiation by assessing the effects on blood counts and in-field skin andhair toxicity. Finally, we compared the efficacy of MMC and Promitil in chemoradiotherapy using mouse xenograft models. Mitomycin C was activated and released from Promitil in a controlled-release profile, and the rate of release was significantly increased in medium from previously irradiated cells. Both Promitil and MMC potently radiosensitized HT-29cells invitro. Toxicity of MMC (8.4mg/kg) was substantially greater than with equivalent doses of Promitil (30mg/kg). Mice treated with human-equivalent doses of MMC (3.3mg/kg) experienced comparable levels of toxicity as Promitil-treated mice at 30 mg/kg. Promitil improved the antitumor efficacy of 5-fluorouracil-based chemoradiotherapy in mouse xenograft models of colorectal cancer, while equitoxic doses of MMC did not. We demonstrated that Promitil is an attractive agent for chemoradiotherapy because it demonstrates a radiation-triggered release of active drug. We further demonstrated that Promitil is a well-tolerated and potent radiosensitizer at doses not achievable with free MMC. These results support clinical investigations using Promitil in chemoradiotherapy.

Sustained Release of Mitomycin C from Its Conjugate with Single-Walled Carbon Nanotubes Associated by Pegylated Peptide.

A novel sustained release formulation of mitomycin C (MMC) was developed by employing single-walled carbon nanotubes (SWCNTs) wrapped by designed peptide with polyethylene glycol (PEG) modification (pegylation) as a nano-scale molecular platform. The amino groups of polycationic and amphiphilic H-(-Cys-Trp-Lys-Gly-)(-Lys-Trp-Lys-Gly-)6-OH [CWKG(KWKG)6] peptide associated with SWCNTs were modified using PEG with 12 units (PEG12) to improve the dispersion stability of the composite. Then thiol groups of peptide were conjugated with MMC using N-ε-maleimidocaproic acid (EMCA) as a linker via transformation of aziridine group of MMC. The obtained SWCNTs-CWKG(KWKG)6-(PEG)12-C6-MMC composites particularly that with 13.6% PEG modification extent of amino groups, showed good dispersion stability both in water and in a cell culture medium for 24 h. The release of MMC from SWCNTs-CWKG(KWKG)6-(PEG)12-C6-MMC was confirmed to follow first-order kinetics being accelerated by the pH increase in good agreement with the results observed for MMC-dextran conjugate with the same conjugation structure. The SWCNTs-CWKG(KWKG)6-(PEG)12 composite exhibited a considerably low cytotoxicity against cultured human lung adenocarcinoma epithelial cell line (A549). In contrast, SWCNTs-CWKG(KWKG)6-(PEG)12-C6-MMC demonstrated delayed but relatively corresponding antitumor activity with free MMC at the same concentration. The results suggested the potential role of SWCNTs-CWKG(KWKG)6-(PEG)12 as a carrier for a controlled release drug delivery system (DDS).

Pharmacologic Studies of a Prodrug of Mitomycin C in Pegylated Liposomes (Promitil(®)): High Stability in Plasma and Rapid Thiolytic Prodrug Activation in Tissues.

Pegylated liposomal (PL) mitomycin C lipid-based prodrug (MLP) has recently entered clinical testing. We studied here the preclinical pharmacology of PL-MLP. The stability, pharmacokinetics, biodistribution, and other pharmacologic parameters of PL-MLP were examined. Thiolytic cleavage of MLP and release of active mitomycin C (MMC) were studied using dithiothreitol (DTT), and by incubation with tissue homogenates. MLP was incorporated in the bilayer at 10% molar ratio with nearly 100% entrapment efficiency, resulting in a formulation with high plasma stability. In vitro, DTT induced cleavage of MLP with predictable kinetics, generating MMC and enhancing pharmacological activity. A long circulation half-life of MLP (10-15h) was observed in rodents and minipigs. Free MMC is either extremely low or undetectable in plasma. However, urine from PL-MLP injected rats revealed delayed but significant excretion of MMC indicating in vivo activation of MLP. Studies in mice injected with H3-cholesterol radiolabeled PL-MLP demonstrated relatively greater tissue levels of H3-cholesterol than MLP. MLP levels were highest in tumor and spleen, and very low or undetectable in liver and lung. Rapid cleavage of MLP in various tissues, particularly in liver, was shown in ex-vivo experiments of PL-MLP with tissue homogenates. PL-MLP was less toxic in vivo than equivalent doses of MMC. Therapeutic studies in C26 mouse tumor models demonstrated dose-dependent improved efficacy of PL-MLP over MMC. Thiolytic activation of PL-MLP occurs in tissues but not in plasma. Liposomal delivery of MLP confers a favorable pharmacological profile and greater therapeutic index than MMC.

Single-step assembly of polymer-lipid hybrid nanoparticles for mitomycin C delivery.

Mitomycin C is one of the most effective chemotherapeutic agents for a wide spectrum of cancers, but its clinical use is still hindered by the mitomycin C (MMC) delivery systems. In this study, the MMC-loaded polymer-lipid hybrid nanoparticles (NPs) were prepared by a single-step assembly (ACS Nano 2012, 6:4955 to 4965) of MMC-soybean phosphatidyhlcholine (SPC) complex (Mol. Pharmaceutics 2013, 10:90 to 101) and biodegradable polylactic acid (PLA) polymers for intravenous MMC delivery. The advantage of the MMC-SPC complex on the polymer-lipid hybrid NPs was that MMC-SPC was used as a structural element to offer the integrity of the hybrid NPs, served as a drug preparation to increase the effectiveness and safety and control the release of MMC, and acted as an emulsifier to facilitate and stabilize the formation. Compared to the PLA NPs/MMC, the PLA NPs/MMC-SPC showed a significant accumulation of MMC in the nuclei as the action site of MMC. The PLA NPs/MMC-SPC also exhibited a significantly higher anticancer effect compared to the PLA NPs/MMC or free MMC injection in vitro and in vivo. These results suggested that the MMC-loaded polymer-lipid hybrid NPs might be useful and efficient drug delivery systems for widening the therapeutic window of MMC and bringing the clinical use of MMC one step closer to reality.

Therapeutic effect of folate-targeted and PEGylated phytosomes loaded with a mitomycin C-soybean phosphatidyhlcholine complex.

A mitomycin C (MMC)-soybean phosphatidyhlcholine complex loaded in phytosomes was previously reported for the purpose of developing a MMC drug delivery system (Mol. Pharmaceutics 2013, 10, 90-101), but this approach was limited by rapid elimination from the body and lack of target specificity. In this article, to overcome these limitations, MMC-soybean phosphatidyhlcholine complex-loaded phytosomes (MMC-loaded phytosomes) as drug carriers were surface-functionalized with folate-PEG (FA-PEG) to achieve reduced toxicity and a superior MMC-mediated therapeutic effect. For this purpose, FA was conjugated to DSPE-PEG-NH2, and the resultant DSPE-PEG-FA was introduced into the lipid moiety of the phytosomes via a postinsertion technique. The prepared FA-PEG-functionalized MMC-loaded phytosomes (FA-PEG-MMC-loaded phytosomes) have a particle size of 201.9 ± 2.4 nm, a PDI of 0.143 ± 0.010, a zeta potential of -27.50 ± 1.67 mV, a spherical shape, and sustained drug release. The remarkable features of FA-PEG-MMC-loaded phytosomes included increased cellular uptake in HeLa cells and higher accumulation in H22 tumor-bearing mice over that of the PEG-MMC-loaded phytosomes. Furthermore, FA-PEG-MMC-loaded phytosomes were associated with enhanced cytotoxic activity in vitro and an improved antitumor effect in vivo compared to that resulting from free MMC injection. These results suggest that FA-PEG-MMC-loaded phytosomes may be useful drug delivery systems for widening the therapeutic window of MMC in clinical trials.

Mitomycin C-soybean phosphatidylcholine complex-loaded self-assembled PEG-lipid-PLA hybrid nanoparticles for targeted drug delivery and dual-controlled drug release.

Most present drug-phospholipid delivery systems were based on a water-insoluble drug-phospholipid complex but rarely water-soluble drug-phospholipid complex. Mitomycin C (MMC) is a water-soluble anticancer drug extensively used in first-line chemotherapy but is limited by its poor aqueous stability in vitro, rapid elimination from the body, and lack of target specificity. In this article, we report the MMC-soybean phosphatidylcholine complex-loaded PEG-lipid-PLA hybrid nanoparticles (NPs) with Folate (FA) functionalization (FA-PEG-PE-PLA NPs@MMC-SPC) for targeted drug delivery and dual-controlled drug release. FA-PEG-PE-PLA NPs@MMC-SPC comprise a hydrophobic core (PLA) loaded with MMC-SPC, an amphiphilic lipid interface layer (PE), a hydrophilic shell (PEG), and a targeting ligand (FA) on the surface, with a spherical shape, a nanoscaled particle size, and high drug encapsulation efficiency of almost 95%. The advantage of the new drug delivery systems is the early phase controlled drug release by the drug-phospholipid complex and the late-phase controlled drug release by the pH-sensitive polymer-lipid hybrid NPs. In vitro cytotoxicity and hemolysis assays demonstrated that the drug carriers were cytocompatible and hemocompatible. The pharmacokinetics study in rats showed that FA-PEG-PE-PLA NPs@MMC-SPC significantly prolonged the blood circulation time compared to that of the free MMC. More importantly, FA-PEG-PE-PLA NPs@MMC-SPC presented the enhanced cell uptake/cytotoxicity in vitro and superior tumor accumulation/therapeutic efficacy in vivo while reducing the systemic toxicity. A significant accumulation of MMC in the nuclei as the site of MMC action achieved in FA-PEG-PE-PLA NPs@MMC-SPC made them ideal for MMC drug delivery. This study may provide an effective strategy for the design and development of the water-soluble drug-phospholipid complex-based targeted drug delivery and sustained/controlled drug release.

Riboflavin-Targeted Polymer Conjugates for Breast Tumor Delivery

In breast cancer, a significant decrease in riboflavin (RF) serum levels and increase in RF carrier protein occurs, indicating a potential role of RF in disease progression. To evaluate RF's ability to serve as a targeting agent, mitomycin C (MMC)-conjugated N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers were synthesized and targeted to the RF internalization pathway in human breast cancer cells. Competitive uptake studies were used to determine specificity of RF-targeted conjugates, and an MTT assay established the IC₅₀ for the conjugates. Endocytic mechanisms were investigated by confocal microscopy. Studies revealed a high-affinity endocytic mechanism for RF-specific internalization of fluorescently-labeled conjugates in both MCF-7 and SKBR-3 cells, whereas folic acid-mediated endocytosis showed high specificity only in SKBR-3 cells. MMC internalization was significantly higher following nontargeted and RF-targeted MMC-conjugate administration compared to that of free MMC. Cytotoxic analysis illustrated potent IC₅₀ values for RF-targeted MMC conjugates similar to free MMC. Maximum nuclear accumulation of MMC resulted from lysosomal release from RF-targeted and nontargeted MMC-conjugates following 6 h incubations, unlike that of free MMC seen within 10 min. Targeting polymer-MMC conjugates to the RF internalization pathway in breast cancer cells enabled an increase in MMC uptake and nuclear localization, resulting in potent cytotoxic activity.

477P - Liposomal Prodrug of Mitomycin C with Thiolytic Activation: Improved Therapeutic Index Over Mitomycin C in Preclinical Studies

ABSTRACT Disclosure A.A. Gabizon: I am the founder and Chief Scientist of Lipomedix Inc., a company with a vested interest in the product discussed in this presentation. Y. Amitay: Paid employee of Lipomedix, a product of which is discussed here. All other authors have declared no conflicts of interest. We have developed a formulation of a mitomycin-C lipid-based prodrug (MLP) in pegylated liposomes (PL) in which MLP is activated by thiolytic cleavage to mitomycin C (MMC). PL-MLP (PROMITIL™) was previously reported to have reduced toxicity and an improved therapeutic index as compared to MMC in human and mouse tumor models. In the following studies, we examined the pharmacokinetics, toxicity, and therapeutic activity of scaled-up batches of PL-MLP (prepared under the same protocol design as for clinical batches) in rodent and miniswine species. PL-MLP is a liquid suspension of vesicles of ∼100 nm diameter with MLP entrapped in the lipid bilayer at 10% molar ratio. Pharmacokinetic studies revealed major (>100-fold) differences in Cmax, AUC, plasma clearance and volume of distribution between MMC (i.v. 3 mg/kg) and PL-MLP (i.v. 6 mg/kg in MMC-equivalents). While MMC is cleared from blood within minutes and extensively distributed to peripheral tissues, PL-MLP is cleared very slowly with a mono-exponential half-life of ∼15 hours in rats and has a limited volume distribution roughly equivalent to the blood volume. In rat toxicity studies in rats, the MTD of PL-MLP was two to three-fold higher than that of MMC in mg-equivalent doses. Therapeutic studies in BALB/c mice inoculated i.p. with C26 tumor cells show a clear survival advantage for treatment with PL-MLP over free MMC at all dose levels tested, whether treatment was administered by the i.v. or by the i.p. route. In the porcine model, no acute infusion reaction to i.v. administration of PL-MLP was observed. PL-MLP appears to be a stable formulation with minimal prodrug activation and release of MMC in circulation, yet significant antitumor activity, indicating in vivo prodrug activation in tumors. PL-MLP may represent an effective therapeutic tool in a broad spectrum of malignancies, including multi-drug resistant tumors, with improved safety over free MMC, and is due to be tested in a human phase I study in 2012.

A novel nanoparticle formulation overcomes multiple types of membrane efflux pumps in human breast cancer cells.

Multidrug resistance (MDR) in cancer cells can involve overexpression of different types of membrane drug efflux pumps and other drug resistance mechanisms. Hence, inhibition of one resistance mechanism may not be therapeutically effective. Previously we demonstrated a new polymer lipid hybrid nanoparticle (PLN) system was able to circumvent drug resistance of P-glycoprotein (P-gp) overexpressing breast cancer cells. The objectives of the present study were 2-fold: (1) to evaluate the ability of the PLN system to overcome two other membrane efflux pumps-multidrug resistance protein 1 (MRP1+) and breast cancer resistance protein (BCRP+) overexpressed on human breast cancer cell lines MCF7 VP (MRP1+) and MCF7 MX (BCRP+); and (2) to evaluate possible synergistic effects of doxorubicin (Dox)-mitomycin C (MMC) in these cell lines. These objectives were accomplished by measuring in vitro cellular uptake, intracellular trafficking, and cytotoxicity (using a clonogenic assay and median effect analysis), of Dox, MMC, or Dox-MMC co-loaded PLN. Treatment of MDR cells with PLN encapsulating single anticancer agents significantly enhanced cell kill compared to free Dox or MMC solutions. Dox-MMC co-loaded PLN were 20-30-folds more effective in killing MDR cells than free drugs. Co-encapsulated Dox-MMC was more effective in killing MDR cells than single agent-encapsulated PLN. Microscopic images showed perinuclear localization of fluorescently labelled PLN in all cell lines. These results are consistent with our previous results for P-gp overexpressing breast cancer cells suggesting the PLN system can overcome multiple types of membrane efflux pumps increasing the cytotoxicity of Dox-MMC at significantly lower doses than free drugs.

Intracellular Delivery of Mitomycin C with Targeted Polysaccharide Conjugates Against Multidrug Resistance

Intracellular targeted conjugates of xyloglucan and mitomycin C (MMC) were synthesized with a lysosomally degradable peptide spacer and galactosamine, a terminal moiety that can be used to target polymeric conjugates to hepatoma. The content of the MMC was about 3.5% (mol) in this conjugate. In an in vitro cytotoxicity experiment, the targeted prodrugs have higher cytotoxicity than free MMC against the drug resistant HepG2 cells. In a human tumor xenograft nude mouse model, the targeted prodrugs generated higher therapeutic effect than non-targeted prodrugs or free MMC. Together, these results suggest that targeted prodrugs, which have improved transfer efficiency and hepatocyte specificity, may be useful for the reversion of drug resistant HepG2 cells.

Mitomycin C-dextran conjugate: a novel high molecular weight pro-drug of mitomycin C.

A high molecular weight derivative of mitomycin C (MMC), mitomycin C-dextran conjugate (MMC-D) has been synthesized and its biological and pharmacological properties investigated. MMC is released from MMC-D in vitro with a half-life of 24 h. After intraperitoneal injection of MMC-D, free MMC could be detected in plasma and urine of mouse for 5--8 h, while MMC administered as a free form was eliminated rapidly. After MMC-D, given to mice bearing Ehrlich ascites carcinoma or B16 melanoma there was a reduction in toxicitst that the high molecular weight MMC-dextran derivative is a kind of pro-drug which persists in the body giving a sustained release of free MMC thus significantly increasing the antitumour activity of the parent drug.

Hyaluronan-grafted particle clusters loaded with Mitomycin C as selective nanovectors for primary head and neck cancers

CD44, a well-documented cell surface receptor, is involved in cell proliferation, migration, signaling, adhesion, differentiation and angiogenesis, which are important properties for normal and cancerous cell function. We recently developed particle clusters coated with hyaluronan (termed gagomers; GAG), and showed that they can deliver the insoluble drug paclitaxel directly into CD44-over-expressing tumors in a mouse tumor model. Here, we tested primary head and neck cancers (HNC) and normal cells taken from the same patient, and found that although CD44 expression in both types of cells was high, GAGs bind only to the cancerous cells in a selective manner. We next formulated the anti cancer agent mitomycin C (MMC) in the GAGs. MMC-based chemoradiation is a potential treatment for HNC, however, due to patient’s toxicity, MMC is not part of the standard treatment of HNC. MMC encapsulation efficiency was about 70% with a half-life drug efflux of 1.2 ± 0.3 days. The Ex vivo study of the targeted MMC-GAG showed significant increase in the therapeutic effect on HNC cells (compared to free MMC), while it had no effect on normal cells taken from the same patient. These results demonstrate the specificity of the nanovectors towards head and neck cancers, which might be applicable as future therapy to many CD44-expressing tumors.

Using Activated Carbon Nanoparticles to Decrease the Genotoxicity and Teratogenicity of Anticancer Therapeutic Agents

One of the key obstacles against the success in cancer chemotherapy is the toxic and side effects of the chemotherapeutic agents. The avoidance of these toxic and side effects will greatly improve the therapeutic effects of anticancer drugs while decrease the pains of the patients. Here we show that activated carbon nanoparticles (ACNP), one of the mesoporous nanoparticles, can decrease the genotoxicity and teratogenicity of mitomycin C (MMC). To study the effects of ACNP on genotoxicity and teratogenicity of MMC, methods of PCE micronucleus test, Chinese hamster lung cell chromosome aberration experiment and rat teratogenicity were employed to observe the differences in genotoxicity and teratogenicity between ACNP-adsorbed MMC (ACNP-MMC) and free MMC. Results demonstrated that free MMC 0.16-5.0 microg/kg significantly increased the positive rate of PCE micronucleus test, the chromosome aberration rate and rat teratogenecity, but ACNP-MMC did not increased these heredity and reproduction toxicological indexes in a dose range of 0.625-10.0 microg/kg. From these results, it can be concluded that ACNP-MMC have significant effects to decrease the genotoxicity and teratogenicity effects of MMC. These results will have a considerable impact on the strategy of anticancer chemotherapy.

Antitumor activity of new liposomal prodrug of mitomycin C in multidrug resistant solid tumor: Insights of the mechanism of action

The antitumor activity of a novel thiolytically cleavable lipid-based prodrug of mitomycin C (MMC) delivered by STEALTH® liposomes (SL) was studied in drug resistant human ovarian carcinoma A2780/AD model and compared with free MMC and both free and SL forms of an established anticancer drug—doxorubicin (DOX). It was found that SL-prodrug (SL-pMMC) possessed enhanced antitumor activity when compared with the parent MMC, free DOX, and SL-DOX. An observance of the high antitumor efficiency of SL-pMMC was a result of its preferential accumulation in the tumor by the enhanced permeability and retention (EPR) effect, suppression of multidrug resistance (MDR) associated with P-glycoprotein and MRP drug efflux pumps, activation of caspase-dependent apoptosis signaling pathways and suppression of antiapoptotic cellular defense by increasing the BAX/BCL2 ratio. Consequently, the described SL-pMMC formulations can be considered good candidates for the chemotherapy of multidrug resistant tumors.