Doxorubicin-Conjugated Anti-Midkine Monoclonal Antibody as a Potential Anti-Tumor Drug

Precise Photodynamic Therapy by Midkine Nanobody-Engineered Nanoparticles Remodels the Microenvironment of Pancreatic Ductal Adenocarcinoma and Potentiates the Immunotherapy

Pancreatic ductal adenocarcinoma (PDAC) is notorious for its resistance against chemotherapy and immunotherapy due to its dense desmoplastic and immunosuppressive tumor microenvironment (TME). Traditional photodynamic therapy (PDT) was also less effective for PDAC owing to poor selectivity, insufficient penetration, and accumulation of photosensitizers in tumor sites. Here, we designed a light-responsive novel nanoplatform targeting the TME of PDAC through tumor-specific midkine nanobodies (Nbs), which could efficiently deliver semiconducting polymeric nanoparticles (NPs) to the TME of PDAC and locally produce abundant reactive oxygen species (ROS) for precise photoimmunotherapy. The synthesized nanocomposite can not only achieve multimodal imaging of PDAC tumors (fluorescence and photoacoustic imaging) but also lead to apoptosis and immunogenic cell death of tumor cells via ROS under light excitation, ultimately preventing tumor progression and remodeling the immunosuppressive TME with increased infiltration of T lymphocytes. Combined with a PD-1 checkpoint blockade, the targeted PDT platform showed the best antitumor performance and markedly extended mice survival. Conclusively, this work integrating Nbs with photodynamic NPs provides a novel strategy to target formidable PDAC to achieve tumor suppression and activate antitumor immunity, creating possibilities for boosting efficacy of immunotherapy for PDAC tumors through the combination with precise local PDT.

The role of midkine in health and disease

Midkine (MDK) is a neurotrophic growth factor highly expressed during embryogenesis with important functions related to growth, proliferation, survival, migration, angiogenesis, reproduction, and repair. Recent research has indicated that MDK functions as a key player in autoimmune disorders of the central nervous system (CNS), such as Multiple Sclerosis (MS) and is a promising therapeutic target for the treatment of brain tumors, acute injuries, and other CNS disorders. This review summarizes the modes of action and immunological functions of MDK both in the peripheral immune compartment and in the CNS, particularly in the context of traumatic brain injury, brain tumors, neuroinflammation, and neurodegeneration. Moreover, we discuss the role of MDK as a central mediator of neuro-immune crosstalk, focusing on the interactions between CNS-infiltrating and -resident cells such as astrocytes, microglia, and oligodendrocytes. Finally, we highlight the therapeutic potential of MDK and discuss potential therapeutic approaches for the treatment of neurological disorders.

Role of Midkine in Cancer Drug Resistance: Regulators of Its Expression and Its Molecular Targeting

Molecules involved in drug resistance can be targeted for better therapeutic efficacies. Research on midkine (MDK) has escalated in the last few decades, which affirms a positive correlation between disease progression and MDK expression in most cancers and indicates its association with multi-drug resistance in cancer. MDK, a secretory cytokine found in blood, can be exploited as a potent biomarker for the non-invasive detection of drug resistance expressed in various cancers and, thereby, can be targeted. We summarize the current information on the involvement of MDK in drug resistance, and transcriptional regulators of its expression and highlight its potential as a cancer therapeutic target.

Shedding more light on the role of Midkine in hepatocellular carcinoma: New perspectives on diagnosis and therapy

One of the most common malignant tumors is hepatocellular carcinoma (HCC). Progression of HCC mainly results from highly complex molecular and pathological pathways. Midkine (MDK) is a growth factor that impacts viability, migration, and other cell activities. Since MDK has been involved in the inflammatory responses, it has been claimed that MDK has a crucial role in HCC. MDK acts as an anti-apoptotic factor, which mediates tumor cell viability. In addition, MDK blocks anoikis to promote metastasis. There is also evidence that MDK is involved in angiogenesis. It has been shown that the application of anti-MDK approaches might be promising in the treatment of HCC. Besides, due to the elevated expression in HCC, MDK has been proposed as a biomarker in the prognosis and diagnosis of HCC. In this review, we will discuss the role of MDK in HCC. It is hoped that the development of new strategies concerning MDK-based therapies will be promising in HCC management.

Gemcitabine-(5'-phosphoramidate)-[anti-IGF-1R]: molecular design, synthetic organic chemistry reactions, and antineoplastic cytotoxic potency in populations of pulmonary adenocarcinoma (A549)

One molecular-based approach that increases potency and reduces dose-limited sequela is the implementation of selective 'targeted' delivery strategies for conventional small molecular weight chemotherapeutic agents. Descriptions of the molecular design and organic chemistry reactions that are applicable for synthesis of covalent gemcitabine-monophosphate immunochemotherapeutics have to date not been reported. The covalent immunopharmaceutical, gemcitabine-(5'-phosphoramidate)-[anti-IGF-1R] was synthesized by reacting gemcitabine with a carbodiimide reagent to form a gemcitabine carbodiimide phosphate ester intermediate which was subsequently reacted with imidazole to create amine-reactive gemcitabine-(5'-phosphorylimidazolide) intermediate. Monoclonal anti-IGF-1R immunoglobulin was combined with gemcitabine-(5'-phosphorylimidazolide) resulting in the synthetic formation of gemcitabine-(5'-phosphoramidate)-[anti-IGF-1R]. The gemcitabine molar incorporation index for gemcitabine-(5'-phosphoramidate)-[anti-IGF-R1] was 2.67:1. Cytotoxicity Analysis - dramatic increases in antineoplastic cytotoxicity were observed at and between the gemcitabine-equivalent concentrations of 10-9  M and 10-7  M where lethal cancer cell death increased from 0.0% to a 93.1% maximum (100.% to 6.93% residual survival), respectively. Advantages of the organic chemistry reactions in the multistage synthesis scheme for gemcitabine-(5'-phosphoramidate)-[anti-IGF-1R] include their capacity to achieve high chemotherapeutic molar incorporation ratios; option of producing an amine-reactive chemotherapeutic intermediate that can be preserved for future synthesis applications; and non-dedicated organic chemistry reaction scheme that allows substitutions of either or both therapeutic moieties, and molecular delivery platforms.

Design of a doxorubicin-peptidomimetic conjugate that targets HER2-positive cancer cells

Doxorubicin (DOX) belongs to the anthracycline class of drugs that are used in the treatment of various cancers. It has limited cystostatic effects in therapeutic doses, but higher doses can cause cardiotoxicity. In the current approach, we conjugated a peptidomimetic (Arg-aminonaphthylpropionic acid-Phe, compound 5) known to bind to HER2 protein to DOX via a glutaric anhydride linker. Antiproliferative assays suggest that the DOX-peptidomimetic conjugate has activity in the lower micromolar range. The conjugate exhibited higher toxicity in HER2-overexpressed cells than in MCF-7 and MCF-10A cells that do not overexpress HER2 protein. Cellular uptake studies using confocal microscope experiments showed that the conjugate binds to HER2-overexpressed cells and DOX is taken up into the cells in 4 h compared to conjugate in MCF-7 cells. Binding studies using surface plasmon resonance indicated that the conjugate binds to the HER2 extracellular domain with high affinity compared to compound 5 or DOX alone. The conjugate was stable in the presence of cells with a half-life of nearly 4 h and 1 h in human serum. DOX is released from the conjugate and internalized into the cells in 4 h, causing cellular toxicity. These results suggest that this conjugate can be used to target DOX to HER2-overexpressing cells and can improve the therapeutic index of DOX for HER2-positive cancer.

Anti-Neoplastic Cytotoxicity of Gemcitabine-(C4-amide)-[anti-EGFR] in Dual-combination with Epirubicin-(C3-amide)-[anti-HER2/neu] against Chemotherapeutic-Resistant Mammary Adenocarcinoma (SKBr-3) and the Complementary Effect of Mebendazole

AIMS

Delineate the feasibility of simultaneous, dual selective "targeted" chemotherapeutic delivery and determine if this molecular strategy can promote higher levels anti-neoplastic cytotoxicity than if only one covalent immunochemotherapeutic is selectively "targeted" for delivery at a single membrane associated receptor over-expressed by chemotherapeutic-resistant mammary adenocarcinoma.

METHODOLOGY

Gemcitabine and epirubicin were covalently bond to anti-EGFR and anti-HER2/neu utilizing a rapid multi-phase synthetic organic chemistry reaction scheme. Determination that 96% or greater gemcitabine or epirubicin content was covalently bond to immunoglobulin fractions following size separation by micro-scale column chromatography was established by methanol precipitation analysis. Residual binding-avidity of gemcitabine-(C4-amide)-[anti-EG-FR] applied in dual-combination with epirubicin-(C3-amide)-[anti-HER2/neu] was determined by cell-ELIZA utilizing chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3) populations. Lack of fragmentation or polymerization was validated by SDS-PAGE/immunodetection/chemiluminescent autoradiography. Anti-neoplastic cytotoxic potency was determined by vitality stain analysis of chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3) monolayers known to uniquely over-express EGFR (2 × 105/cell) and HER2/neu (1 × 106/cell) receptor complexes. The covalent immunochemotherapeutics gemcitabine-(C4-amide)-[anti-EGFR] and epirubicin-(C3-amide)-[anti-HER2/neu] were applied simultaneously in dual-combination to determine their capacity to collectively evoke elevated levels of anti-neoplastic cytotoxicity. Lastly, the tubulin/microtubule inhibitor mebendazole evaluated to determine if it's potential to complemented the anti-neoplastic cytotoxic properties of gemcitabine-(C4-amide)-[anti-EGFR] in dual-combination with epirubicin-(C3-amide)-[anti-HER2/neu].

RESULTS

Dual-combination of gemcitabine-(C4-amide)-[anti-EGFR] with epirubicin-(C3-amide)-[anti-HER2/neu] produced greater levels of anti-neoplastic cytotoxicity than either of the covalent immunochemotherapeutics alone. The benzimidazole microtubule/tubulin inhibitor, mebendazole complemented the anti-neoplastic cytotoxicity of gemcitabine-(C4-amide)-[anti-EGFR] in dual-combination with epirubicin-(C3-amide)-[anti-HER2/neu].

CONCLUSIONS

The dual-combination of gemcitabine-(C4-amide)-[anti-EGFR] with epirubicin-(C3-amide)-[anti-HER2/neu] produced higher levels of selectively "targeted" anti-neoplastic cytotoxicity against chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3) than either covalent immunochemotherapeutic alone. The benzimidazole tubulin/microtubule inhibitor, mebendazole also possessed anti-neoplastic cytotoxicity against chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3) and complemented the potency and efficacy of gemcitabine-(C4-amide)-[anti-EGFR] in dual-combination with epirubicin-(C3-amide)-[anti-HER2/neu].

Novel peptide-doxorubucin conjugates for targeting breast cancer cells including the multidrug resistant cells

The efficacy of chemotherapeutic doxorubucin (Dox) in cancer treatment is limited by two main factors, nonspecific toxicity and the emergence of tumor resistance. To overcome these hurdles, in this study peptide-Dox conjugates were prepared. A decapeptide 18-4a (NH₂-WxEAAYQkFL-CONH₂) [corrected] with high specificity for breast cancer cells and improved proteolytic stability was conjugated to Dox to give peptide-Dox ester (1) and amide (2) conjugates. Cell uptake studies showed that the conjugates were 6-10 times selective for breast cancerous cells (MCF-7 and MDA-MB-435) over noncancerous cells (HUVECs and MCF-10A). Conjugate 1 displayed similar toxicity as free Dox toward the breast cancerous cells and was about 40 times less toxic toward the noncancerous cells and 4-fold more toxic toward the Dox resistant MDA-MB-435-MDR cells than the free Dox. These data suggest that conjugate 1 can be used as a potential prodrug for improving the therapeutic index of Dox and potentially many other cytotoxic drugs.

Transferrin as a drug carrier: Cytotoxicity, cellular uptake and transport kinetics of doxorubicin transferrin conjugate in the human leukemia cells

Leukemias are one of most common malignancies worldwide. There is a substantial need for new chemotherapeutic drugs effective against this cancer. Doxorubicin (DOX), used for treatment of leukemias and solid tumors, is poorly efficacious when it is administered systemically at conventional doses. Therefore, several strategies have been developed to reduce the side effects of this anthracycline treatment. In this study we compared the effect of DOX and doxorubicin-transferrin conjugate (DOX-TRF) on human leukemia cell lines: chronic erythromyeloblastoid leukemia (K562), sensitive and resistant (K562/DOX) to doxorubicin, and acute lymphoblastic leukemia (CCRF-CEM). Experiments were also carried out on normal cells, peripheral blood mononuclear cells (PBMC). We analyzed the chemical structure of DOX-TRF conjugate by using mass spectroscopy. The in vitro growth-inhibition assay XTT, indicated that DOX-TRF is more cytotoxic for leukemia cells sensitive and resistant to doxorubicin and significantly less sensitive to normal cells compared to DOX alone. During the assessment of intracellular DOX-TRF accumulation it was confirmed that the tested malignant cells were able to retain the examined conjugate for longer periods of time than normal lymphocytes. Comparison of kinetic parameters showed that the rate of DOX-TRF efflux was also slower in the tested cells than free DOX. The results presented here should contribute to the understanding of the differences in antitumor activities of the DOX-TRF conjugate and free drug.

Biodistribution, kinetics, and biological fate of SPION microbubbles in the rat

Background

In the present investigation, we studied the kinetics and biodistribution of a contrast agent consisting of poly(vinyl alcohol) (PVA) microbubbles containing superparamagnetic iron oxide (SPION) trapped between the PVA layers (SPION microbubbles).

Methods

The biological fate of SPION microbubbles was determined in Sprague-Dawley rats after intravenous administration. Biodistribution and elimination of the microbubbles were studied in rats using magnetic resonance imaging for a period of 6 weeks. The rats were sacrificed and perfusion-fixated at different time points. The magnetic resonance imaging results obtained were compared with histopathologic findings in different organs.

Results

SPION microbubbles could be detected in the liver using magnetic resonance imaging as early as 10 minutes post injection. The maximum signal was detected between 24 hours and one week post injection. Histopathology showed the presence of clustered SPION microbubbles predominantly in the lungs from the first time point investigated (10 minutes). The frequency of microbubbles declined in the pulmonary vasculature and increased in pulmonary, hepatic, and splenic macrophages over time, resulting in a relative shift from the lungs to the spleen and liver. Meanwhile, macrophages showed increasing signs of cytoplasmic iron accumulation, initially in the lungs, then followed by other organs.

Conclusion

The present investigation highlights the biological behavior of SPION microbubbles, including organ distribution over time and indications for biodegradation. The present results are essential for developing SPION microbubbles as a potential contrast agent and/or a drug delivery vehicle for specific organs. Such a vehicle will facilitate the use of multimodality imaging techniques, including ultrasound, magnetic resonance imaging, and single positron emission computed tomography, and hence improve diagnostics, therapy, and the ability to monitor the efficacy of treatment.

A human anti-c-Met Fab fragment conjugated with doxorubicin as targeted chemotherapy for hepatocellular carcinoma

c-Met is over-expressed in hepatocellular carcinoma(HCC) but is absent or expressed at low levels in normal tissues. Therefore we generated a novel conjugate of a human anti-c-Met Fab fragment (MetFab) with doxorubicin (DOX) and assessed whether it had targeted antitumor activity against HCC and reduced the side-effects of DOX. The MetFab was screened from human phage library, conjugated with DOX via chemical synthesis, and the conjugation MetFab-DOX was confirmed by HPLC. The drug release patterns, the binding efficacy, and cellular distribution of MetFab-DOX were assessed. MetFab-DOX was stable at pH7.2 PBS while release doxorubicin quickly at pH4.0, the binding efficacy of MetFab-DOX was similarly as MetFab, and the cellular distribution of the MetFab-DOX is distinct from free DOX. The cytotoxicity of MetFab-DOX was analyzed by the MTT method and the nude mouse HCC model. The MetFab-DOX demonstrated cytotoxic effects on c-Met expressing-tumor cells, but not on the cells without c-Met expression. MetFab-DOX exerted anti-tumor effect and significantly reduced the side effect of free DOX in mice model. Furthermore, the localization of conjugate was confirmed by immunofluorescence staining of tumor tissue sections and optical tumor imaging, respectively, and the tissue-distribution of drug was compared between free DOX and MetFab-DOX treatment by spectrofluorometer. MetFab-DOX can localize to the tumor tissue, and the concentration of doxorubicin in the tumor was higher after MetFab-DOX administration than after DOX administration. In summary, MetFab-DOX can target c-Met expressing HCC cells effectively and have obvious antitumor activity with decreased side-effects in preclinical models of HCC.

Structure–function analysis of full-length midkine reveals novel residues important for heparin binding and zebrafish embryogenesis

Midkine is a heparin-binding di-domain growth factor, implicated in many biological processes as diverse as angiogenesis, neurogenesis and tumorigenesis. Elevated midkine levels reflect poor prognosis for many carcinomas, yet the molecular and cellular mechanisms orchestrating its activity remain unclear. At the present time, the individual structures of isolated half domains of human midkine are known and its functionally active C-terminal half domain remains a popular therapeutic target. In the present study, we determined the structure of full-length zebrafish midkine and show that it interacts with fondaparinux (a synthetic highly sulfated pentasaccharide) and natural heparin through a previously uncharacterized, but highly conserved, hinge region. Mutating six consecutive residues in the conserved hinge to glycine strongly abates heparin binding and midkine embryogenic activity. In contrast with previous in vitro studies, we found that the isolated C-terminal half domain is not active in vivo in embryos. Instead, we have demonstrated that the N-terminal half domain is needed to enhance heparin binding and mediate midkine embryogenic activity surprisingly in both heparin-dependent and -independent manners. Our findings provide new insights into the structural features of full-length midkine relevant for embryogenesis, and unravel additional therapeutic routes targeting the N-terminal half domain and conserved hinge.

ADAM17-overexpressing breast cancer cells selectively targeted by antibody-toxin conjugates

A disintegrin and metalloproteinase 17 (ADAM17) is significantly upregulated not only in malignant cells but also in the pro-inflammatory microenvironment of breast cancer. There, ADAM17 is critically involved in the processing of tumor-promoting proteins. Therefore, ADAM17 appears to be an attractive therapeutic target to address not only tumor cells but also the tumor-promoting environment. In a previous study, we generated a monoclonal anti-ADAM17 antibody (A300E). Although showing no complement-dependent cytotoxicity or antibody-dependent cellular cytotoxicity, the antibody was rapidly internalized by ADAM17-expressing cells and was able to transport a conjugated toxin into target cells. As a result, doxorubicin-coupled A300E or Pseudomonas exotoxin A-loaded A300E was able to kill ADAM17-expressing cells. This effect was strictly dependent on the presence of ADAM17 on the surface of target cells. As a proof of principle, both immunotoxins killed MDA-MB-231 breast cancer cells in an ADAM17-dependent manner. These data suggest that the use of anti-ADAM17 monoclonal antibodies as a carrier might be a promising new strategy for selective anti-cancer drug delivery.

Synthesis of Gemcitabine-(C4-amide)-[anti-HER2/neu] Utilizing a UV-Photoactivated Gemcitabine Intermediate: Cytotoxic Anti-Neoplastic Activity against Chemotherapeutic-Resistant Mammary Adenocarcinoma SKBr-3

Gemcitabine is a pyrimidine nucleoside analog that becomes triphosphorylated intracellularly where it competitively inhibits cytidine incorporation into DNA strands. Another mechanism-of-action of gemcitabine (diphosphorylated form) involves irreversible inhibition of the enzyme ribonucleotide reductase thereby preventing deoxyribonucleotide synthesis. Functioning as a potent chemotherapeutic gemcitabine promote decreases in neoplastic cell proliferation and apoptosis which is frequently found to be effective for the treatment of several leukemias and a wide spectrum of carcinomas. A brief plasma half-life in part due to rapid deamination and chemotherapeutic-resistance restricts the utility of gemcit-abine in clinical oncology. Selective "targeted" delivery of gemcitabine represents a potential molecular strategy for simultaneously prolonging its plasma half-life and minimizing innocient tissues and organ systems exposure to chemotherapy. The molecular design and an organic chemistry based synthesis reaction is described that initially generates a UV-photoactivated gemcitabine intermediate. In a subsequent phase of the synthesis method the UV-photoactivated gemcitabine intermediate is covalently bonded to a monoclonal immunoglobulin yielding an end-product in the form of gemcitabine-(C₄-amide)-[anti-HER2/neu]. Analysis by SDS-PAGE/chemiluminescent auto-radiography did not detect evidence of gemcitabine-(C₄-amide)-[anti-HER2/neu] polymerization or degradative fragmentation while cell-ELISA demonstrated retained binding-avidity for HER2/neu trophic membrane receptor complexes highly over-expressed by chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3). Compared to chemotherapeutic-resistant mammary adenocarcinoma (SKBr-3), the covalent immunochemotherapeutic, gemcitabine-(C₄-amide)-[anti-HER2/neu] is anticipated to exert greater levels of cytotoxic anti-neoplastic potency against other neoplastic cell types like pancreatic carcinoma, small-cell lung carcinoma, neuroblastoma, glioblastoma, oral squamous cell carcinoma, cervical epitheliod carcinoma, or leukemia/lymphoid neoplastic cell types based on their reported sensitivity to gemcitabine and gemcitabine covalent conjugates.

Synthesis of a covalent epirubicin-(C(3)-amide)-anti-HER2/neu immunochemotherapeutic utilizing a UV-photoactivated anthracycline intermediate

The C(3)-monoamine on the carbohydrate moiety (daunosamine -NH(2)-3') of epirubicin was reacted under anhydrous conditions with succinimidyl 4,4-azipentanoate to create a covalent UV-photoactivated epirubicin-(C(3)-amide) intermediate with primary amine-reactive properties. A synthetic covalent bond between the UV-photoactivated epirubicin-(C(3)-amide) intermediate and the ɛ-amine of lysine residues within the amino acid sequence of anti-HER2/neu monoclonal immunoglobulin was subsequently created by exposure to UV light (354 nm) for 15 minutes. Size-separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis combined with immunodetection analysis and chemiluminescent autoradiographic imaging revealed a lack of IgG-IgG polymerization or degradative protein fragmentation of the covalent epirubicin-(C(3)-amide)-[anti-HER2/neu] immunochemotherapeutic. Retained binding-avidity of epirubicin-(C(3)-amide)-[anti-HER2/neu] was validated by cell-ELISA utilizing monolayer populations of chemotherapeutic-resistant mammary adenocarcinoma SKBr-3 which highly overexpress membrane-associated HER2/neu complexes. Between epirubicin-equivalent concentrations of 10(-10) to 10(-6) M the covalent epirubicin-(C(3)-amide)-[anti-HER2/neu] immunochemotherapeutic consistently evoked levels of cytotoxic anti-neoplastic potency that were highly analogous to chemotherapeutic-equivalent concentrations of epirubicin. Cytotoxic anti-neoplastic potency of epirubicin-(C(3)-amide)-[anti-HER2/neu] against chemotherapeutic-resistant mammary adenocarcinoma SKBr-3 challenged with epirubicin-(C(3)-amide)-[anti-HER2/neu] at an epirubicin-equivalent concentration of 10(-6) M was 88.5% (e.g., 11.5% residual survival). Between final epirubicin-equivalent concentrations of 10(-8) and 10(-7) M there was a marked threshold increase in the mean cytotoxic anti-neoplastic activity for epirubicin-(C(3)-amide)-[anti-HER2/neu] from 9.9% to 66.9% (90.2% to 33.1% residual survival).

A conjugate of an anti-midkine single-chain variable fragment to doxorubicin inhibits tumor growth

Doxorubicin (DOX) was conjugated to a single-chain variable fragment (scFv) against human midkine (MK), and the conjugate (scFv-DOX) was used to target the chemotherapeutic agent to a mouse solid tumor model in which the tumor cells expressed high levels of human MK. The His-tagged recombinant scFv was expressed in bacteria, purified by metal affinity chromatography, and then conjugated to DOX using oxidative dextran (Dex) as a linker. The molecular formula of this immunoconjugate was scFv(Dex)_1.3(DOX)₂₀. In vitro apoptosis assays showed that the scFv-DOX conjugate was more cytotoxic against MK-transfected human adenocarcinoma cells (BGC823-MK) than untransfected cells (55.3 ± 2.4 vs 22.4 ± 3.8%) for three independent experiments. Nude mice bearing BGC823-MK solid tumors received scFv-DOX or equivalent doses of scFv + DOX for 2 weeks and tumor growth was more effectively inhibited by the scFv-DOX conjugate than by scFv + DOX (51.83% inhibition vs 40.81%). Histological analysis of the tumor tissues revealed that the highest levels of DOX accumulated in tumors from mice treated with scFv-DOX and this resulted in more extensive tumor cell death than in animals treated with the equivalent dose of scFv + DOX. These results show that the scFv-DOX conjugate effectively inhibited tumor growth in vivo and suggest that antigen-specific scFv may be competent drug-carriers.

Molecular aptamers for drug delivery

The active targeting of drugs in a cell-, tissue- or disease-specific manner represents a potentially powerful technology with widespread applications in medicine, including the treatment of cancers. Aptamers have properties such as high affinity and specificity for targets, easy chemical synthesis and modification, and rapid tissue penetration. They have become attractive molecules in diagnostics and therapeutics rivaling and, in some cases, surpassing other molecular probes, such as antibodies. In this review, we highlight the recent progress in aptamer-mediated delivery for therapeutics and disease-targeting based on aptamer integration with a variety of nanomaterials, such as gold nanorods, DNA micelles, DNA hydrogels and carbon nanotubes.

Epirubicin-[Anti-HER2/neu] Synthesized with an Epirubicin-(C13-imino)-EMCS Analog: Anti-Neoplastic Activity against Chemotherapeutic-Resistant SKBr-3 Mammary Carcinoma in Combination with Organic Selenium

PURPOSE

Discover the anti-neoplastic efficacy of epirubicin-(C₁₃-imino)-[anti-HER2/neu] against chemotherapeutic-resistant SKBr-3 mammary carcinoma and delineate the capacity of selenium to enhance it's cytotoxic anti-neoplastic potency.

METHODS

In molar excess, EMCH was combined with epirubicin to create a covalent epirubicin-(C₁₃-imino)-EMCH-maleimide intermediate with sulfhydryl-reactive properties. Monoclonal immunoglobulin selective for HER2/neu was then thiolated with 2-iminothiolane at the terminal ε-amine group of lysine residues. The sulfhydryl-reactive epirubicin-(C₁₃-imino)-EMCH intermediate was then combined with thiolated anti-HER2/neu monoclonal immunoglobulin. Western-blot analysis was utilized to characterize the molecular weight profiles while binding of epirubicin-(C₁₃-imino)-[anti-HER2/neu] to membrane receptors was determined by cell-ELISA utilizing populations of SKBr-3 mammary carcinoma that highly over-expresses HER2/neu complexes. Anti-neoplastic potency of epirubicin-(C₁₃-imino)-[anti-HER2/neu] between the epirubicin-equivalent concentrations of 10^-12 M and 10^-7 M was determined by vitality staining analysis with and without the presence of selenium (5 μM).

RESULTS

Epiribucin-(C₁₃-imino)-[anti-HER2/neu] between epirubicin-equivalent concentrations of 10^-8 M to 10^-7 M consistently evoked higher anti-neoplastic potency than "free" non-conjugated epirubicin which corresponded with previous investigations utilizing epirubicin-(C₃-amide)-[anti-HER2/neu] and epirubicin-(C₃-amide)-[anti-EGFR]. Selenium at 5 mM consistently enhanced the cytotoxic anti-neoplastic potency of epirubicin-(C13-imino)-[anti-HER2/neu] at epirubicin equivalent concentrations (10-12 to 10-7 M).

CONCLUSIONS

Epirubicin-(C₁₃-imino)-[anti-HER2/neu] is more potent than epirubicin against chemotherapeutic-resistant SKBr-3 mammary carcinoma and selenium enhances epirubicin-(C₁₃-imino)-[anti-HER2/neu] potency. The methodology applied for synthesizing epirubicin-(C₁₃-imino)-[anti-HER2/neu] is relatively time convenient and has low instrumentation requirements.

Synthesis of a covalent gemcitabine-(carbamate)-[anti-HER2/neu] immunochemotherapeutic and its cytotoxic anti-neoplastic activity against chemotherapeutic-resistant SKBr-3 mammary carcinoma

Gemcitabine is a potent chemotherapeutic that exerts cytotoxic activity against several leukemias and a wide spectrum of carcinomas. A brief plasma half-life in part due to rapid deamination and chemotherapeutic-resistance frequently limit the utility of gemcitabine in clinical oncology. Selective 'targeted' delivery of gemcitabine represents a potential molecular strategy for simultaneously prolonging its plasma half-life and minimizing exposure of innocent tissues and organ systems.

MATERIALS AND METHODS

Gemcitabine was combined in molar excess with N-[p-maleimidophenyl]-isocyanate (PMPI) so that the isocyanate moiety of PMPI which exclusively reacts with hydroxyl groups preferentially created a carbamate covalent bond at the terminal C(5)-methylhydroxy group of gemcitabine. Monoclonal immunoglobulin with binding-avidity specifically for HER2/neu was thiolated with 2-iminothiolane at the terminal ε-amine group of lysine amino acid residues. The gemcitabine-(carbamate)-PMPI intermediate with a maleimide moiety that exclusively reacts with reduced sulfhydryl groups was then combined with thiolated anti-HER2/neu monoclonal immunoglobulin. Western-blot analysis was utilized to delineate the molecular weight profile for gemcitabine-(carbamate)-[anti-HER2/neu] while cell binding characteristics were determined by cell-ELISA utilizing SKBr-3 mammary carcinoma which highly over-expresses HER2/neu receptors. Cytotoxic anti-neoplastic potency of gemcitabine-(carbamate)-[anti-HER2/neu] between the gemcitabine-equivalent concentrations of 10(-12) and 10(-6)M was determined utilizing vitality staining analysis of chemotherapeutic-resistant SKBr-3 mammary carcinoma.

RESULTS

Gemcitabine-(carbamate)-[anti-HER2/neu] was synthesized at a molar incorporation index of 1:1.1 (110%) and had a molecular weight of 150kDa that was indistinguishable from reference control immunoglobulin fractions. Cell-ELISA detected progressive increases in SKBr-3 mammary carcinoma associated immunoglobulin with corresponding increases in covalent gemcitabine immunochemotherapeutic concentrations. The in vitro cytotoxic anti-neoplastic potency of gemcitabine-(carbamate)-[anti-HER2/neu] was approximately 20% and 32% at 10(-7) and 10(-6)M (gemcitabine-equivalent concentrations) after a 182-h incubation period.

DISCUSSION

The investigations describes for the first time a methodology for synthesizing a gemcitabine anti-HER2/neu immunochemotherapeutic by creating a covalent bond structure between the C(5)-methylhydroxy group of gemcitabine and thiolated lysine amino acid residues of monoclonal antibody or other biologically active protein fractions. Gemcitabine-(carbamate)-[anti-HER2/neu] possessed binding-avidity at HER2/neu receptors highly over-expressed by chemotherapeutic-resistant SKBr-3 mammary carcinoma. Alternatively, gemcitabine can be covalently linked at its C(5)-methylhydroxy group to monoclonal immunoglobulin fractions that possess binding-avidity for other receptors and membrane complexes uniquely highly over-expressed by a variety of neoplastic cell types. Compared to chemotherapeutic-resistant SKBr-3 mammary carcinoma, gemcitabine-(carbamate)-[anti-HER2/neu] immunochemotherapeutic is anticipated to exert higher levels of cytotoxic anti-neoplastic potency against other neoplastic cell types like pancreatic carcinoma, small-cell lung carcinoma, neuroblastoma, glioblastoma, oral squamous cell carcinoma, cervical epithelioid carcinoma, or leukemia/lymphoid neoplastic cell types based on their reportedly greater sensitivity to gemcitabine and gemcitabine covalent conjugates.

Novel method of doxorubicin-SPION reversible association for magnetic drug targeting

A new method of reversible association of doxorubicin (DOX) to superparamagnetic iron oxide nanoparticles (SPION) is developed for magnetically targeted chemotherapy. The efficacy of this approach is evaluated in terms of drug loading, delivery kinetics and cytotoxicity in vitro. Aqueous suspensions of SPION (ferrofluids) were prepared by coprecipitation of ferric and ferrous chlorides in alkaline medium followed by surface oxidation by ferric nitrate and surface treatment with citrate ions. The ferrofluids were loaded with DOX using a pre-formed DOX-Fe(2+) complex. The resulting drug loading was as high as 14% (w/w). This value exceeds the maximal loading known from literature up today. The release of DOX from the nanoparticles is strongly pH-dependent: at pH 7.4 the amount of drug released attains a plateau of approximately 85% after 1h, whereas at pH 4.0 the release is almost immediate. At both pH, the released drug is iron-free. The in vitro cytotoxicity of the DOX-loaded SPION on the MCF-7 breast cancer cell line is similar to that of DOX in solution or even higher, at low-drug concentrations. The present study demonstrates the potential of the novel method of pH-sensitive DOX-SPION association to design novel magnetic nanovectors for chemotherapy.

New frontiers in nanotechnology for cancer treatment

Nanotechnology is a field of research at the crossroads of biology, chemistry, physics, engineering, and medicine. Design of multifunctional nanoparticles capable of targeting cancer cells, delivering and releasing drugs in a regulated manner, and detecting cancer cells with enormous specificity and sensitivity are just some examples of the potential application of nanotechnology to oncological diseases. In this review we discuss the recent advances of cancer nanotechnology with particular attention to nanoparticle systems that are in clinical practice or in various stages of development for cancer imaging and therapy.

siRNA targeting midkine inhibits gastric cancer cells growth and induces apoptosis involved caspase-3,8,9 activation and mitochondrial depolarization

Midkine (MK), a heparin-binding growth factor, is expressed highly in various malignant tumors, so it acts as attractive therapeutic target. In the present study, we used siRNA targeting MK to downregulate human MK expression in human gastric cancer cell line BGC823 and SGC7901 so as to determine the advantages of this anticancer therapeutic. The cell proliferation was evaluated by a WST-8 (4-[3-(2-methoxy-4-nitrophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1, 3-benzene disulfonate sodium salt) assay and colony formation assay. Apoptosis was determined by flow cytometer analysis and colorimetric assay. Our results showed that the BGC823 and SGC7901 cell growth were significantly inhibited by knockdown of MK gene. The loss of mitochondrial membrane potential, release of cytochrome c from the mitochondria into cytosol and increased activity of caspase-3, 8 and 9 occurred concomitantly with inhibition of MK gene. These results indicated that siRNA targeting MK gene can inhibit gastric cancer cells growth and induce apoptosis via mitochondrial depolarization and caspase-3 activation. MK siRNA may be a promising novel and potential therapeutic strategy for the treatment of gastric cancers.