In silico designing and expression of novel recombinant construct containing the variable part of CD44 extracellular domain for prediagnostic breast cancer

Selective Hydrolysis of Ovalbumin by Zr-Based Lacunary Polyoxotungstate in Surfactant Solutions

This study aims to design an artificial metalloprotease based on a Zr-containing polyoxometalate Na8[Zr(W5O18)2] [Zr(W5)2] for the hydrolysis of ovalbumin (OVA) in the presence of different surfactants, which can be used in many areas of the biological and medical sciences, particularly for targeted proteolytic drug design. For this reason, parameters, including the free energy of binding, the chemical nature of amino acid residues, secondary structures, and electrostatic potentials, of Zr(W5)2-OVA and Zr(W5)2-OVA-surfactant were analyzed by molecular docking simulations. The investigations showed that the presence of surfactants decreases the binding affinity of Zr(W5)2 for OVA amino acids, and hydrogen bonds and van der Waals interactions are formed between Zr(W5)2 and OVA amino acids. Additionally, GROMACS further illustrated the significance of SDS and CTAB surfactants in influencing the conformational changes of the OVA that lead to selective protein hydrolysis. In agreement with molecular dynamics simulation results, the experimental analysis showed more protein hydrolysis for the Zr(W5)2-OVA-surfactant systems. For instance, circular dichroism spectroscopy indicated that Zr(W5)2-OVA-CTAB and Zr(W5)2-OVA-TX-100 were more hydrolytically efficient due to the increased level of β-structures rather than α-chains, which showed that surfactants can facilitate the accessibility of Zr(W5)2 to the cleavage sites by inducing partial unfolding of the OVA structure.

Preparation of chitosan nanoparticle containing recombinant CD44v antigen and evaluation of its immunization capacity against breast cancer in BALB/c mice

OBJECTIVE(S)

Breast tumors show heterogeneity containing cancer stem cells as a small subpopulation of a tumor mass. CD44 as a cancer stem cells antigen is abnormally expressed by carcinomas of epithelial origin. Also, overexpression of CD44 variable isoforms (CD44v) is associated with malignancy in breast cancer. In the present research, our objective was to evaluate the immunogenicity of prepared nanoparticles containing a novel recombinant CD44v (rCD44v) protein in the mouse model.

MATERIALS AND METHODS

CD44 gene was expressed in E. coli BL21 DE3 using the pET28a-CD44 vector. The expressed rCD44v protein was purified, encapsulated into the chitosan nanoparticles, and administered to BALB/c mice. ELISA was used to evaluate the immunoglobulin levels of immunized animals. For challenge experiment, 2 × 10⁶ 4T1-CD44 tumor cells were injected subcutaneously in mice, and tumor size, necrosis, and metastases were measured. Finally, cell proliferation assay, cytokines assay, and neutralization assay of the mouse anti-rCD44v on the human breast cancer cell line were examined.

RESULTS

The measured size of chitosan-rCD44v nanoparticles was 146.5 nm. Recombinant CD44v encapsulated by chitosan nanoparticles increases immunological responses via the adjuvant nature of chitosan nanoparticles. In the immunized mice, IgG and IgA titers were significantly increased. Tumor growth in injection and nano-injection test groups compared with the mice control groups displayed a significant reduction (P < 0.05). A high amount of splenocytes secreting IFNγ and IL-17 was seen in immunized mice with rCD44v (P < 0.05). Furthermore, a smaller size of lung metastases compared to the control mice groups was detected.

CONCLUSION

The encapsulated rCD44v within the chitosan nanoparticles induced a significant immune response in mice and can establish significant protection against breast cancer. Therefore, it can be considered a vaccine candidate for breast cancer therapeutic modalities.