Immunization with a recombinant GnRH vaccine fused to heat shock protein 65 inhibits mammary tumor growth in vivo

Active immunization with recombinant GnRH6-CRM197 inhibits reproductive function of male rats

Gonadotropin-releasing hormone (GnRH) vaccines have been successfully used for the inhibition of gonadal development and function, but current GnRH-based vaccines often present variability in the response. Cross-reactive material 197 (CRM197) has been used as carrier molecules to enhance an immune response to associated antigens. So, the synthetic mammalian tandem-repeated GnRH hexamer (GnRH6) gene was integrated into the expression plasmid pET-21a. Recombinant GnRH6-CRM197 protein was subsequently overexpressed in Escherichia coli strain BL21 and purified through Nickel column affinity chromatography and the antigenicity and biological effects of GnRH6-CRM197 were evaluated in rats. Sixteen 4-month-old adult male rats were randomly divided into two groups: the GnRH6-CRM197 group (n = 8) and the control group (n = 8). The GnRH6-CRM197 group rats were subcutaneously immunized with 100 μg of GnRH6-CRM197, administered thrice at 2-week intervals with GnRH6-CRM197.The control group received only a white oil adjuvant. Following the initial immunization, the weights of animals were recorded, and blood samples were collected from the orbital sinus at 4, 4.5, 5, 5.5, 6, 6.5, and 7 months. Serum antibody titers and testosterone concentrations were quantified using ELISA and CLIA, respectively. Additionally, testicular tissues were collected for morphological examination. The results revealed a significant increase in serum GnRH antibody titers (p < 0.05), but a significant decrease in serum testosterone concentrations (p < 0.05), and the weight, length, width, and girth of the testis, and the number of spermatogonia cells, spermatocytes, and sperm cells in the immunized rats. Furthermore, seminiferous tubules revealed significant atrophy and no sperm were observed in the immunized animals. Thus, GnRH6-CRM197 may be an effective antigen and a potential immunocastration vaccine.

Novel molecules as the emerging trends in cancer treatment: an update

As per World Health Organization cancer remains as a leading killer disease causing nearly 10 million deaths in 2020. Since the burden of cancer increases worldwide, warranting an urgent search for anti-cancer compounds from natural sources. Secondary metabolites from plants, marine organisms exhibit a novel chemical and structural diversity holding a great promise as therapeutics in cancer treatment. These natural metabolites target only the cancer cells and the normal healthy cells are left unharmed. In the emerging trends of cancer treatment, the natural bioactive compounds have long become a part of cancer chemotherapy. In this review, we have tried to compile about eight bioactive compounds from plant origin viz. combretastatin, ginsenoside, lycopene, quercetin, resveratrol, silymarin, sulforaphane and withaferin A, four marine-derived compounds viz. bryostatins, dolastatins, eribulin, plitidepsin and three microorganisms viz. Clostridium, Mycobacterium bovis and Streptococcus pyogenes with their well-established anticancer potential, mechanism of action and clinical establishments are presented.

Mycobacteria-Based Vaccines as Immunotherapy for Non-urological Cancers

The arsenal against different types of cancers has increased impressively in the last decade. The detailed knowledge of the tumor microenvironment enables it to be manipulated in order to help the immune system fight against tumor cells by using specific checkpoint inhibitors, cell-based treatments, targeted antibodies, and immune stimulants. In fact, it is widely known that the first immunotherapeutic tools as immune stimulants for cancer treatment were bacteria and still are; specifically, the use of Mycobacterium bovis bacillus Calmette-Guérin (BCG) continues to be the treatment of choice for preventing cancer recurrence and progression in non-invasive bladder cancer. BCG and also other mycobacteria or their components are currently under study for the immunotherapeutic treatment of different malignancies. This review focuses on the preclinical and clinical assays using mycobacteria to treat non-urological cancers, providing a wide knowledge of the beneficial applications of these microorganisms to manipulate the tumor microenvironment aiming at tumor clearance.

Inhibition of mouse RM-1 prostate cancer and B16F10 melanoma by the fusion protein of HSP65 & STEAP1 186-193

The research of tumor vaccine plays a crucial role in tumor immunotherapy. This study has constructed and prepared a fusion protein vaccine of heat shock protein 65 (HSP65) and the octapeptide epitope 186-193 of the six transmembrane epithelial antigen of the prostate 1 (STEAP1 _186-193), and investigated the inhibitory effect of the fusion protein on mouse RM-1 prostate cancer and B16F10 melanoma xenografts. The fusion protein His-HSP65-STEAP1 _186-193 (HHST1), His-HSP65-2×STEAP1 _186-193 (HHST2) and His-HSP65-6×STEAP1 _186-193 (HHST6) were obtained by setting different copy number of STEAP1 _186-193 and adding His purification tag before HSP65. Firstly the inhibitory effect of fusion protein on mouse RM-1 prostate cancer xenografts has been studied, which could be the basis of the study the inhibitory effect of the best fusion protein on mouse B16F10 melanoma xenografts. All studies compared with the fusion protein His-HSP65 (HHSP65), the fusion proteins HHST1, HHST2 and HHST6 all could significantly inhibit the growth of mouse RM-1 prostate cancer xenografts. In addition, the fusion protein HHST2 was proved to be the best compared with the fusion proteins HHST1 and HHST6 (P<0.05). Apart from this, compared with the fusion protein HHSP65, the fusion protein HHST2 also significantly inhibited the growth of mouse beared B16F10 melanoma. The results above indicate that HSP65 and STEAP1 _186-193 can significantly inhibit the growth of mouse RM-1 prostate cancer and B16F10 melanoma xenografts, and the appropriate increase of copy number can effectively improve that the fusion protein has an excellent anti-tumor ability.

Humoral immune responses against gonadotropin releasing hormone elicited by immunization with phage-peptide constructs obtained via phage display

Phage display is based on genetic engineering of phage coat proteins resulting in fusion peptides displayed on the surface of phage particles. The technology is widely used for generation of phages with novel characteristics for numerous applications in biomedicine and far beyond. The focus of this study was on development of phage-peptide constructs that stimulate production of antibodies against gonadotropin releasing hormone (GnRH). Phage-peptide constructs that elicit production of neutralizing GnRH antibodies can be used for anti-fertility and anti-cancer applications. Phage-GnRH constructs were generated via selection from a phage display library using several types of GnRH antibodies as selection targets. Such phage constructs were characterized for sequence similarities to GnRH peptide and frequency of their occurrence in the selection rounds. Five of the constructs with suitable characteristics were tested in mice as a single dose 5×10(11) virions (vir) vaccine and were found to be able to stimulate production of GnRH-specific antibodies, but not to suppress testosterone (indirect indicator of GnRH antibody neutralizing properties). Next, one of the constructs was tested at a higher dose of 2×10(12) vir per mouse in combination with a poly(lactide-co-glycolide) (PLGA)-based adjuvant. This resulted in multifold increase in GnRH antibody production and significant reduction of serum testosterone, indicating that antibodies produced in response to the phage-GnRH immunization possess neutralizing properties. To achieve optimal immune responses for desired applications, phage-GnRH constructs can be modified with respect to flanking sequences of GnRH-like peptides displayed on phage. Anticipated therapeutic effects also might be attained using optimized phage doses, a combination of several constructs in a single treatment, or application of adjuvants and advanced phage delivery systems.

Immunocontraception for Animals: Current Status and Future Perspective

An alternative to surgical sterilization for fertility control of animals (wild, zoo, farm, and domestic) is needed to prevent problems related to overpopulation, including culling and relocation. A PubMed and Google Scholar database search was conducted using the keywords 'contraceptive vaccine animals,' 'immunocontraception animals,' 'non-surgical sterilization animals,' 'PZP vaccine,' and 'GnRH vaccine.' The searches from 1972 to 2015 yielded over 1500 publications. These articles were read, and 375 were selected for detailed analysis. Articles referenced in these publications were also thoroughly examined. PZP and GnRH contraceptive vaccines (CVs) have been extensively investigated for fertility control of wild, zoo, farm, and domestic animal populations. Both vaccines have shown tremendous success with PZP vaccines taking the lead. Novel technologies and targets are being developed to improve existing vaccines and generate second-generation CVs. Single-shot vaccines, which can be delivered remotely, will greatly advance the field of immunocontraception for animal use with potential human application.

Detection of antibodies against customized epitope: use of a coating antigen employing VEGF as fusion partner

Diagnosis of many infectious, autoimmune diseases and cancers depends on the detection of specific antibodies against peptide epitope by enzyme-linked immunosorbent assay (ELISA). However, small peptides are difficult to be coated on the plate surfaces. In this study, we selected GnRH as a model hapten to evaluate whether VEGF121 would be suitable as an irrelevant hapten-carrier to develop a universal platform for specific antibodies detection. Firstly, GnRH was fused to the C terminus of VEGF121 and the resultant fusion protein VEGF-GnRH expressed effectively as inclusion bodies in Escherichia coli. Thereafter, VEGF-GnRH was easily purified to near homogeneity with a yield of about 235 mg from 2.1 L induced culture. At last, VEGF-GnRH was used to perform ELISA and western blot, and our results suggested that VEGF-GnRH was capable of detecting anti-GnRH antibodies in sera both qualitatively and quantitatively. Indeed, previous studies of our laboratory had demonstrated that other fusion proteins such as VEGF-Aβ10, VEGF-GRP, VEGF-CETPC, and VEGF-βhCGCTP37 were able to detect their corresponding antibodies specifically. Therefore, VEGF121 may be a suitable irrelevant fusion partner of important diagnostic peptide markers. Our works would shed some light on the development of a universal platform for detection of specific antibodies.