The receptor tyrosine kinase (EphB4), which produces erythropoietin, was identified as a molecular target for cancer. We identified six peptides as potential inhibitors of EphB4 using an integrated approach combining online bioinformatics tools. According to PeptideRanker, CSM-peptides, SCMTHP, and AcPEP analysis, all peptides are effective against cancer, with the exception of LTAPGQATLPT and VEQNLVPGLK. Furthermore, Toxin-Pred predicts that none of the peptides are toxic, and that only VQLPGWRVFP and TMKGPPDTLQ are potentially allergenic using AllerTop server. PepSite2, HPEPDOCK, and MDockPeP servers were utilized to perform molecular docking, and PacDock was used to examine molecular interactions. The docking score (kcal/mol) range of six promising anticancer peptides against EphB4 was recorded as follows: VQLPGWRVFP (-240.72), FTKDDEWSCFPF (-201.74), SYLPPLSAEVTAK (-177.52), LTAPGQATLPT (-162.23), VEQNLVPGLK (-157.30), TMKGPPDTLQ (-149.67). The main bindings on the allosteric site to VQLPGWRVFP were with R706, S815, R819 and P843 on EphB4. Collectively, our results demonstrated that M. oleifera peptides ameliorate cancer by inhibiting EphB4, and they are promising candidates for the prevention and treatment of cancer.

The erythropoietin-producing hepatocellular carcinoma (Eph) receptors are the largest receptor tyrosine kinases family. EphB4 is essential for cell adhesion and motility during embryogenesis. Pathologically, EphB4 is overexpressed and contributes to poor prognosis in various tumors. Therefore, sensitive monoclonal antibodies (mAbs) should be developed to predict the prognosis for multiple tumors with high EphB4 expression, including breast and gastric cancers. This study aimed to develop highly sensitive and specific anti-EphB4 mAbs for several applications using the Cell-Based Immunization and Screening (CBIS) method. EphB4-overexpressed Chinese hamster ovary (CHO)-K1 (CHO/EphB4) cells were immunized into mice, and we established an anti-EphB4 mAb (clone B4Mab-7), which is applicable for flow cytometry, western blotting, and immunohistochemistry. B4Mab-7 reacted with endogenous EphB4-positive breast cancer cell lines, MCF-7 and MDA-MB-468, but did not react with EphB4-knockout MCF-7 (BINDS-52) in flow cytometry. Dissociation constant (KD) values were determined to be 2.9 × 10‑9 M, 1.3 × 10‑9 M, and 3.3 × 10‑9 M by flow cytometric analysis for CHO/EphB4, MCF-7, and MDA-MB-468 cells, respectively. B4Mab-7 detected the EphB4 protein bands from breast cancer cells in western blotting, and stained breast cancer tissues immunohistochemistry. Altogether, B4Mab-7 demonstrated high sensitivity and specificity against EphB4 in various applications.