In silico approach to probe the binding affinity between OMVs harboring the ZEGFR affibody and the EGF receptor

There is a growing interest in designing a nanocarrier containing an EGFR targeting affibody to direct toward cancer cells. Here, cytolysin A was cloned at the N-terminus of Z_EGFR:1907 affibody to guarantee its surface presentation on the OMVs while targeting the epidermal growth factor receptors (EGFRs). A separate construct including a fusogenic peptide (GALA) was also designed for the endosomal escape of the nanocarrier. Binding of the two constructs ClyA-affi_EGFR and ClyA-affi_EGFR-GALA to domain III of EGFR was investigated using molecular docking and molecular dynamic simulations. The higher stability of the ClyA-affi_EGFR-GALA/EGFR as compared to the ClyA-affi_EGFR/EGFR complex was evident. The ClyA-affi_EGFR-GALA structure showed a higher RMSD during the first half of the simulation time implying a much less stable behavior. Plateau state of the radius of gyration plot of ClyA-affi_EGFR-GALA confirmed a well-folded structure in the presence of the GALA sequence. Solvent accessible surface area for both proteins was in the same range. The data obtained from hydrogen bond analysis revealed a more equilibrated and stable form of the ClyA-affi_EGFR-GALA structure upon interaction with EGFR. The data provided here was a requisite for our biological evaluation of the synthesized constructs as a component of a novel drug delivery system.

Surface Engineering of Escherichia coli-Derived OMVs as Promising Nano-Carriers to Target EGFR-Overexpressing Breast Cancer Cells

Bacterial outer membrane vesicles (OMVs) have recently drawn a great deal of attention due to their therapeutic efficiency and ability to target specific cells. In the present study, we sought to probe engineered OMVs as novel and promising carriers to target breast cancer cells. Following the fusion of the affi_EGFR-GALA structure to the C-terminal of ClyA as an anchor protein, the ClyA-affi_EGFR-GALA construct was successfully expressed on the surface of ∆msbB/∆pagP E. coli W3110-derived OMVs. Morphological features of the engineered and wild-type OMVs were identical. The engineered OMVs induced no endotoxicity, cytotoxicity, or immunogenicity, indicating the safety of their application. These OMVs could specifically bind to EGF receptors of MDA-MB-468 cells expressing high levels of EGFR and not to those with low levels of EGFR (HEK293T cells). Interestingly, despite a lower binding affinity of the engineered OMVs relative to the positive control Cetuximab, it was strong enough to identify these cells. Moreover, confocal microscopy revealed no uptake of the modified OMVs by the EGFR-overexpressing cells in the presence of EGFR competitors. These results suggest that OMVs might internalize into the cells with EGF receptors, as no OMVs entered the cells with any EGFR expression or those pretreated with EGF or Cetuximab. Regarding the EGFR-binding affinity of the engineered OMVs and their cellular uptake, they are presented here as a potential carrier for cell-specific drug delivery to treat a wide variety of cancer cells. Interestingly, the engineered OMVs are capable of reaching the cytoplasm while escaping the endosome due to the incorporation of a fusogenic GALA peptide in the construct.

Anti-proliferative and apoptotic activities of constituents of chloroform extract of Juglans regia leaves

OBJECTIVES

To evaluate anti-proliferative as well as apoptotic activities of compounds identified in chloroform extract of Juglans regia leaves, on human breast and oral cancer cell lines (MCF-7 and BHY).

MATERIALS AND METHODS

Column chromatography, MTT assay, flowcytometry and western blotting have all been used in the study.

RESULTS

Bioassay-guided fractionation of chloroform extract of J. regia afforded isolation of 5-hydroxy-3,7,4'-trimethoxyflavone [1], lupeol [2], daucosterol [3], 4-hydroxy-α-tetralone [4], β-sitosterol [5], 5,7- dihydroxy-3,4'-dimethoxyflavone [6] and regiolone [7]. Structures of the compounds were established on the basis of spectroscopic analyses [Nuclear magnetic resonance (NMR) and mass]. All compounds inhibited proliferation of MCF-7 (human breast adenocarcinoma) and BHY (human oral squamous carcinoma) cells in a concentration-dependent manner. Compounds 6 and 7 had potent cytotoxic effects on both MCF-7 and BHY cells (IC50 21-51 μm), yet were not toxic to normal cells. MCF-7 growth inhibition was attributed to apoptosis; population of apoptotic cells increased from 1.12% in controls to 5.64 and 8.1% after 48-h treatment with compounds 6 and 7, indicating their potential at inducing early and late apoptosis. The caspase cascade was not activated, as indicated by only insignificant cleavage of caspase-3.

CONCLUSIONS

Our results suggest that compounds 6 and 7 can induce apoptosis in MCF-7 cells through the caspase-3 independent pathway.

Cytotoxicity effects of various Juglans regia (walnut) leaf extracts in human cancer cell lines

CONTEXT

Currently, natural products have been shown to present interesting biological and pharmacological activities and are used as chemotherapeutic agents. Plants have historically been used in treating cancer and are recognized for their ability to produce secondary metabolites. Juglans regia L. (Juglandaceae) has medicinal applications to treat a wide range of diseases such as cancer.

OBJECTIVE

The current study was designed to evaluate the antiproliferative activity of total extract as well as several fractions from the leaves of J. regia.The total phenolics, flavonoids, and condensed tannins content of these extracts were also determined to obtain further information on the correlation between the contents of phenolic compounds and antiproliferative effects as well as the leaf developmental stages.

MATERIALS AND METHODS

Antiproliferative activity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and flow cytometry methods against human oral cancer, breast adenocarcinoma and colon adenocarcinoma cell lines. The total phenolics, flavonoids, and condensed tannins were determined by Folin-Ciocalteu, aluminum chloride and butanol-HCl colorimetric methods.

RESULTS

Our present study has shown that chloroform fraction has the lowest IC(50) values (0.36-0.81 mg/mL) and also induces cell cycle arrest (G0\G1 phase) after a 24 h treatment. The colorimetric methods showed the highest amount of total phenolics, flavonoids, and condensed tannins in the methanol fraction (120.28 ± 2.32, 59.44 ± 0.87, 227.00 ± 4.91 mg/g of dry weight of extract).

DISCUSSION AND CONCLUSION

The results obtained herein indicate that walnut chloroform fraction may contain effective compounds which can be used as a chemotherapeutic agent.