InVivoMAb anti-human EphA2

<i>In vitro</i> studies of liver stage (LS) development of the human malaria parasite <i>Plasmodium falciparum</i> are technically challenging; therefore, fundamental questions about hepatocyte receptors for invasion that can be targeted to prevent infection remain unanswered. To identify novel receptors and to further understand human hepatocyte susceptibility to <i>P. falciparum</i> sporozoite invasion, we created an optimized <i>in vitro</i> system by mimicking <i>in vivo</i> liver conditions and using the subcloned HC-04.J7 cell line that supports mean infection rates of 3-5% and early development of <i>P. falciparum</i> exoerythrocytic forms-a 3- to 5-fold improvement on current <i>in vitro</i> hepatocarcinoma models for <i>P. falciparum</i> invasion. We juxtaposed this invasion-susceptible cell line with an invasion-resistant cell line (HepG2) and performed comparative proteomics and RNA-seq analyses to identify host cell surface molecules and pathways important for sporozoite invasion of host cells. We identified and investigated a hepatocyte cell surface heparan sulfate proteoglycan, glypican-3, as a putative mediator of sporozoite invasion. We also noted the involvement of pathways that implicate the importance of the metabolic state of the hepatocyte in supporting LS development. Our study highlights important features of hepatocyte biology, and specifically the potential role of glypican-3, in mediating <i>P. falciparum</i> sporozoite invasion. Additionally, it establishes a simple <i>in vitro</i> system to study the LS with improved invasion efficiency. This work paves the way for the greater malaria and liver biology communities to explore fundamental questions of hepatocyte-pathogen interactions and extend the system to other human malaria parasite species, like <i>P. vivax</i>.

Background/aim: EPH receptor A2 (EPHA2) is highly expressed in aggressive types of human cancer, and is expected to be an excellent target molecule for antibody treatments. In this study, we investigated the therapeutic potential of antibody to EPHA2 against melanoma in vitro. Materials and methods: We generated three monoclonal antibodies (mAbs) to EPHA2 and examined cell-surface expression by flow cytometry. To investigate the ability to inhibit tumor cell migration therapy with mAbs to EPHA2, we performed a wound scratch assay and invasion assay. We investigated the therapeutic effects of immunotoxins consisting of toxin-conjugated EPHA2 mAbs. Results: All human melanoma cell lines studied expressed EPHA2. Like natural ligand ephrin-A1, one of EPHA2 mAbs, SHM16, inhibited metastatic behavior of cells, such as migration and invasion. In addition, drastic growth inhibition and cytotoxicity were found using immunotoxin-conjugated SHM16. Conclusion: These observations indicate a promising role for EPHA2 as a target in antibody treatments for melanoma, and demonstrate the potential therapeutic effects of an agonistic antibody to EPHA2.