melitten and Neoplasm-Metastasis

In a series of in vivo and in vitro experiments, it was shown that membrane disrupting lytic peptides (Hecate, Phor14, or Phor21) conjugated to a 15 amino acid segment of the beta chain of CG or to LHRH were able to target and destroy hormone dependent and independent human prostate cancer xenografts in nude mice. In vitro sensitivity of the cells to the drugs was directly related to LH/CG receptor expression, and pretreatment in vitro or in vivo with estrogens or FSH to enhance LH/CG receptor expression capacity and increased sensitivity to the drugs. Administration of unconjugated Hecate and LHRH was ineffective. Most importantly, all of the lytic peptide-betaCG conjugates tested were highly effective in destroying prostate cancer metastatic cells in lymph nodes, bones and lungs.

Topics: Animals; Carcinoma; Cell Survival; Chorionic Gonadotropin, beta Subunit, Human; Gonadotropin-Releasing Hormone; Humans; Male; Melitten; Necrosis; Neoplasm Metastasis; Prostatic Neoplasms

Melittin is the peptide toxin found in bee venom and is effective against cancer cells. To enhance its activity, a branched dimeric form of melittin was designed. The monomeric form of the peptide was more cytotoxic against gastric cancer cells at low concentrations (1-5 μM) than the dimer form, while the cytotoxic effect was comparable at higher concentrations (10 μM). Confocal microscopy showed that both the monomer and dimer forms of melittin with fluorescent label at the C terminus penetrated the cytoplasm and localized at the cell nucleus and disrupted the cell membrane. The results indicated that both peptides localized in the nucleus and no significant difference in penetration was observed between monomer and dimer of melittin. Although the C and N termini are important for melittin activity, using C terminus for dimerization of the peptide resulted in similar activity for the monomer and dimer against bacteria and gastric cancer cells.

Topics: Animals; Anti-Bacterial Agents; Antineoplastic Agents; Bee Venoms; Cell Line, Tumor; Cell Movement; Cell Survival; Dimerization; Female; Gram-Negative Bacteria; Hemolysis; Humans; Melitten; Mice; Mice, Inbred BALB C; Mice, Nude; Microscopy, Confocal; Neoplasm Metastasis; Nuclear Envelope; Protein Conformation; Reactive Oxygen Species; Solid-Phase Synthesis Techniques; Stomach Neoplasms

Specific drug delivery to metastatic tumors remains a great challenge for antimetastasis therapy. We herein report a bioengineered macrophage-based delivery system (LD-MDS) that can be preferentially delivered to lung metastases and intelligently transformed into nanovesicles and secondary nanovesicles for antimetastasis therapy. LD-MDS was prepared by anchoring a legumain-specific propeptide of melittin (legM) and cytotoxic soravtansine (DM4) prodrug onto the membrane of living macrophages. LD-MDS is responsively activated by legumain protease and converted into DM4-loaded exosome-like nanovesicles (DENs), facilitating efficient internalization by metastatic 4T1 cancer cells and considerable cell death. Afterward, the damaged 4T1 cells can release secondary nanovesicles and free drug molecules to destroy neighboring cancer cells. In vivo, LD-MDS displays superior targeting efficiency for lung metastatic lesions with diameters less than 100 μm and remarkably inhibits lung metastasis. This study provides a new opportunity to explore endogenous macrophages as living drug delivery vehicles with controlled drug release to target metastatic lung tumors.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Survival; Cysteine Endopeptidases; Drug Carriers; Drug Liberation; Humans; Lung Neoplasms; Macrophages; Maytansine; Melitten; Mice, Nude; Nanoparticles; Neoplasm Metastasis; Prodrugs

The cause of most cancer deaths is incurable dissemination of cancer cells into vital organs. Current systemic therapies for disseminated cancers provide limited efficacy and are often accompanied by toxic side effects. We have recently shown that local application of epidermal growth factor receptor (EGFR)-targeted polyinosine-cytosine (polyIC) eradicates preestablished EGFR-overexpressing tumors. Here we show for the first time the high efficiency of systemic application of polyIC/melittin-polyethyleneimine-polyethyleneglycol-EGF (polyIC/MPPE) in combination with human immune cells.. Cancer-targeted activation of immune cells was examined in vitro and in vivo following transfection with polyIC/MPPE. The therapeutic efficiency of the strategy was then examined on disseminated EGFR-overexpressing tumors grown in severe combined immunodeficient (SCID) mice.. Intravenous delivery of polyIC/MPPE followed by intraperitoneal injection of peripheral blood mononuclear cells induced the complete cure of SCID mice with preestablished disseminated EGFR-overexpressing tumors, with no adverse toxic effects. The immune cells and the cytokines they produce are localized to the tumor site of the treated animal and contribute decisively to the demise of the tumor cells. The immune system homes to the tumors, due to the chemokines produced by the internalized polyIC.. The EGFR-homing vector loaded with polyIC can be used to treat and possibly cure patients with disseminated EGFR-overexpressing tumors. The possibility of adopting this strategy to treat other tumors that express a protein capable of ligand induced internalization is discussed.

Topics: Animals; Cell Line, Tumor; Epidermal Growth Factor; ErbB Receptors; Gene Expression; Melitten; Mice; Mice, SCID; Neoplasm Metastasis; Neoplasms, Experimental; Poly I-C; Polyethylene Glycols; Polyethyleneimine; RNA, Double-Stranded; Xenograft Model Antitumor Assays

Melittin, a water-soluble toxic peptide derived from bee venom of Apis mellifera was reported to have inhibitory effects on hepatocellular carcinoma (HCC). However, its role in antimetastasis and the underlying mechanism remains elusive. By utilizing both HCC cell lines and an animal model based assay system, we found that Rac1, which has been shown to be involved in cancer cell metastasis, is highly expressed in aggressive HCC cell lines and its activity correlated with cell motility and cytoskeleton polymerization. In addition, Rac1-dependent activity and metastatic potential of aggressive HCC cells are remarkably high in both cellular and nude mouse models. We provide evidence here that melittin inhibits the viability and motility of HCC cells in vitro, which correlates with its suppression of Rac1-dependent activity, cell motility, and microfilament depolymerization. Furthermore, melittin suppresses both HCC metastasis and Rac1-dependent activity in nude mouse models. The specificity of the effect of melittin on Rac1 was confirmed in HCC cells both in vitro and in vivo.. Melittin inhibits tumor cell metastasis by reducing cell motility and migration via the suppression of Rac1-dependent pathway, suggesting that melittin is a potential therapeutic agent for HCC.

Topics: Actin Cytoskeleton; Animals; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Movement; Cell Survival; Disease Models, Animal; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; MAP Kinase Kinase 4; Melitten; Mice; Mice, Nude; Neoplasm Metastasis; rac1 GTP-Binding Protein; Signal Transduction; Xenograft Model Antitumor Assays

In a series of in vivo and in vitro experiments, the concept has been established that breast cancer cells that express LH/CG or LHRH receptors can be targeted and destroyed by constructs consisting of a lytic peptide moiety and a 15-amino acid segment of the beta-chain of CG or by an LHRH lytic peptide conjugate. Data obtained in vitro established the validity of this concept, showed the specificities of the Hecate-betaCG, and Phor14 and Phor21-betaCG conjugates in killing cells that express functional LH/CG receptors and proved that the LH/CG receptor capacity is directly related to the compound's specificity. In in vivo experiments, Hecate-betaCG, Phor14-betaCG, and Phor21-betaCG(ala) each caused highly significant reductions of tumor volume and tumor burden in nude mice bearing breast cancer xenografts; Hecate and Phor21 alone or conjugated with non-specific peptides were not effective. Most importantly, the lytic peptide conjugates were all highly effective in targeting and destroying disseminated breast cancer metastases in lymph nodes, bones, lungs and other organs.

Topics: Amino Acid Sequence; Animals; Breast Neoplasms; Cell Death; Chorionic Gonadotropin, beta Subunit, Human; Female; Gonadotropin-Releasing Hormone; Luciferases; Lung; Lymph Nodes; Melitten; Mice; Mice, Nude; Molecular Sequence Data; Neoplasm Metastasis; Neoplasm Transplantation; Peptide Fragments; Peptides; Spinal Cord; Tumor Burden