A novel recombinant anti-epidermal growth factor receptor peptide vaccine capable of active immunization and reduction of tumor volume in a mouse model.

Over-expression of epidermal growth factor receptor (EGFR) has been reported in a number of human malignancies. Strong expression of this receptor has been associated with poor survival in many such patients. Active immunizations that elicit antibodies of the desired type could be an appealing alternative to conventional passive immunization. In this regard, a novel recombinant peptide vaccine capable of prophylactic and therapeutic effects was constructed. A novel fusion recombinant peptide base vaccine consisting of L2 domain of murine extra-cellular domain-EGFR and EGFR mimotope (EM-L2) was constructed and its prophylactic and therapeutic effects in a Lewis lung carcinoma mouse (C57/BL6) model evaluated. Constructed recombinant peptide vaccine is capable of reacting with anti-EGFR antibodies. Immunization of mice with EM-L2 peptide resulted in antibody production against EM-L2. The constructed recombinant peptide vaccine reduced tumor growth and increased the survival rate. Designing effective peptide vaccines could be an encouraging strategy in contemporary cancer immunotherapy. Investigating the efficacy of such cancer immunotherapy approaches may open exciting possibilities concerning hyperimmunization, leading to more promising effects on tumor regression and proliferation.

Cancer immunotherapy by a recombinant phage vaccine displaying EGFR mimotope: an in vivo study.

To date, several small molecule inhibitors and monoclonal-antibodies (like ICR-62) have been used to treat tumors over-expressing epidermal growth factor receptor (EGFR). However, the limitations associated with these conventional applications accentuate the necessity of alternative approaches. Mimotopes as compelling molecular tools could rationally be employed to circumvent these drawbacks. In the present study, an M13 phage displaying ICR-62 binding peptide mimotope is exploited as a vaccine candidate. It exhibited high affinity towards ICR62 and polyclonal anti-P-BSA antibodies. Following the mice immunization, phage-based mimotope vaccine induced humoral immunity. Elicited anti-EGFR mimotope antibodies were detected using ELISA method. Moreover, the phage vaccine was tested on the Lewis lung carcinoma mice model to investigate the prophylactic and therapeutic effects. The tumor volume was measured and recorded in different animal groups to evaluate the anti-tumor effects of the vaccine. Our data indicate that the reported phage-based mimotope could potentially elicit specific antibodies resulting in low titers of EGFR-specific antibodies and reduced tumor growth. However, in vivo experiments of prophylactic or therapeutic vaccination showed no specific advantage. Furthermore, phage-mimotope vaccine might be a promising approach in the field of cancer immunotherapy.

Epitope mapping of epidermal growth factor receptor (EGFR) monoclonal antibody and induction of growth-inhibitory polyclonal antibodies by vaccination with EGFR mimotope.

One of the proposed approaches in cancer therapy is to induce and direct the patient's own immune system against cancer cells. In this study, we determined the epitope mapping of the rat anti-human epidermal growth factor receptor (EGFR) monoclonal antibody ICR-62 using a phage display of random peptide library and identified a 12 amino acids peptide, which was recognized as a mimotope. The peptide was synthesized and conjugated to bovine serum albumin (BSA) as carrier protein (P-BSA). We have shown that ICR-62 can react specifically with P-BSA as well as native EGFR. Two rabbits were immunized either by BSA or P-BSA and the rabbits IgGs were purified and examined for binding to the antigens, mimotope and the EGFR protein purified from the EGFR overexpressing A431 cell line. We showed that the rabbit IgG generated against the mimotope is capable of inhibiting the growth of A431 cells by 15%, but does not have any effect on the growth of EGFR-negative MDA-MB-453 cell line in vitro. Our results support the need for further investigations on the potential of vaccination with either mimotope of the EGFR or epitope displayed on the surface of phage particles for use in active immunotherapy of cancer.

Construction of a Recombinant Phage-vaccine Capable of Reducing the Growth Rate of an Established LL2 Tumor Model.

Over expression of the epidermal growth factor receptor (EGFR) in many human epithelial tumors has been correlated with disease progression and poor prognosis. EGFR-inhibiting immunotherapy has already been introduced in cancer therapy. Peptide displaying phage particles in eukaryotic hosts can behave as antigen carriers, able to activate the innate immune system and to elicit adaptive immunity. Herein, the M13-pAK8-VIII phagemid plasmid was engineered to contain the sequences for an EGFR mimotope along with the L2 extracellular domain of EGFR (EM-L2) which would produce the final peptide-phage vaccine. The prophylactic and therapeutic effects of this novel vaccine were evaluated on the Lewis lung carcinoma induced mouse (C57/BL6) model. The recombinant peptide was confirmed to be displayed on the surface of M13 phage as an extension for phage's PVIII protein. Immunization of mice with peptide-phage vaccine resulted in antibody production against EM-L2 and significant reduction of tumor growth rate by nearly 25 percent. In conclusion, EM-L2 displaying phage particles could be deemed as an encouraging strategy in contemporary cancer immunotherapy.

A Novel Molecular Design for a Hybrid Phage-DNA Construct Against DKK1.

Nucleic acid immunization has recently exhibited a great promise for immunotherapy of various diseases. However, it is now clear that powerful strategies are imminently needed to improve their efficiency. In this regard, whole bacteriophage particles have been described as efficient DNA vaccine delivery vehicles, capable of circumventing the limitations of naked DNA immunization. Moreover, phage particles could be engineered to display specific peptides on their surfaces. Given these inherent characteristics of phages, we have designed a novel hybrid phage-DNA immunization vector using both M13 and pAAV plasmid elements. Following the construction and in vitro confirmation of the designed vectors, they were used for comparative mice immunization, carrying the same DNA sequence. The results indicated the efficacy of the designed hybrid phage particles, to elicit higher humoral immunity, in comparison to conventional DNA-immunization vectors (pCI). In light of these findings, it could be concluded that using adeno-associated virus (AAV) expression cassette along with displaying TAT peptide on the surface of the phage particle could be deemed as an appealing strategy to enhance the DNA-immunization and vaccination efficacy.

Construction of genetically engineered M13K07 helper phage for simultaneous phage display of gold binding peptide 1 and nuclear matrix protein 22 ScFv antibody.

The most common techniques of antibody phage display are based on the use of M13 filamentous bacteriophages. This study introduces a new genetically engineered M13K07 helper phage displaying multiple copies of a known gold binding peptide on p8 coat proteins. The recombinant helper phages were used to rescue a phagemid vector encoding the p3 coat protein fused to the nuclear matrix protein 22 (NMP22) ScFv antibody. Transmission electron microscopy (TEM), UV-vis absorbance spectroscopy, and field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDX) analysis revealed that the expression of gold binding peptide 1 (GBP1) on major coat protein p8 significantly enhances the gold-binding affinity of M13 phages. The recombinant bacteriophages at concentrations above 5×104 pfu/ml red-shifted the UV-vis absorbance spectra of gold nanoparticles (AuNPs); however, the surface plasmon resonance of gold nanoparticles was not changed by the wild type bacteriophages at concentrations up to 1012 pfu/ml. The phage ELISA assay demonstrated the high affinity binding of bifunctional bacteriophages to NMP22 antigen at concentrations of 105 and 106 pfu/ml. Thus, the p3 end of the bifunctional bacteriophages would be able to bind to specific target antigen, while the AuNPs were assembled along the coat of virus for signal generation. Our results indicated that the complex of antigen-bacteriophages lead to UV-vis spectral changes of AuNPs and NMP22 antigen in concentration range of 10-80µg/ml can be detected by bifunctional bacteriophages at concentration of 104 pfu/ml. The ability of bifunctional bacteriophages to bind to antigen and generate signal at the same time, makes this approach applicable for identifying different antigens in immunoassay techniques.

Attenuation of morphine withdrawal signs, blood cortisol and glucose level with forced exercise in comparison with clonidine.

BACKGROUND: Morphine withdrawal usually results in undesired outcomes, despite partial benefits of alternative medication such as methadone, because of the lack of mental sedation during the withdrawal period, may not lead to the desired result. In this study, forced exercise by treadmill is used to manage morphine dependence in animal model. MATERIALS AND METHODS: Forty adult male mice were divided into 5 groups, from which 4 groups became dependent by increasing daily doses of morphine for 6 days (20-45 mg/kg, SC). Afterwards, the animals were treated for 21 days by either of the following protocol: Positive control (dependent) received once daily 45 mg/kg of morphine sulfate (SC) for 21 day, group under treatment by clonidine (0.4 mg/kg, SC) for 21 day group under treatment by forced exercise by treadmill for 21 day, group under treatment by combination of clonidine (0.4 mg/kg, SC) and forced exercise by treadmill for 21day and the negative control group(independent) received saline injection like other groups. Each of this administration was injected at 8 AM. Finally, in the test day (day 28), all animals received a single dose of naloxone (3 mg/kg, SC) at 8 AM and then were observed for withdrawal signs, and Total Withdrawal Score (TWS) was determined as described previously. After withdrawal sign evaluation for evaluation of stress level of dependent mice, blood cortisol and glucose level were measured in non-fasting situations well. RESULTS: This study showed that TWS significantly decreased in all treatment groups in comparison with positive control group (P < 0.001). Moreover, blood cortisol and glucose level significantly decreased in group under treatment by clonidine (0.4 mg/kg) and group under treatment by combination of clonidine (0.4 mg/kg) and forced exercise by treadmill groups in comparison with control positive (dependent) (P < 0.05). CONCLUSION: This study suggested that forced exercise can be useful as adjunct therapy in dependent people and can ameliorate side effects and stress situation of withdrawal syndrome periods.