Single-chain fragment antibody disrupting the EphA4 function as a therapeutic drug for gastric cancer

Area of Science:

• Oncology
• Molecular Biology
• Immunotherapy

Background:

• Elevated EphA4 expression in gastric cancer correlates with poor prognosis.
• EphA4 presents a potential therapeutic target alongside HER-2/neu.

Purpose of the Study:

• To investigate the efficacy of a novel single-chain variable fragment (scFv) S3 targeting EphA4 in gastric cancer.
• To elucidate the mechanisms underlying scFv S3's anti-cancer effects.

Main Methods:

• Characterization of scFv S3 binding to endogenous EphA4 on gastric cancer cells.
• Assessment of scFv S3's impact on cancer cell growth, migration, and signaling pathways (pAKT, pERK, pSTAT3).
• In vivo studies using a xenograft model to evaluate therapeutic effects and EphA4 degradation.

Main Results:

• scFv S3 demonstrated significant membrane staining and inhibited gastric cancer cell growth and migration.
• Antibody treatment induced EphA4 degradation, involving lysosomal pathways (LAMP1, LAMP2).
• scFv S3 reduced key signaling molecules (pAKT, pERK, pSTAT3) and showed superior efficacy over trastuzumab in a xenograft model.
• In vivo, scFv S3 degraded tumor EphA4, decreased proliferation marker Ki67, and increased cleaved C3 expression.

Conclusions:

• scFv S3 effectively targets EphA4, inhibiting gastric cancer progression through molecular degradation and pathway modulation.
• scFv S3 exhibits therapeutic potential for gastric cancer patients with EphA4 overexpression, outperforming trastuzumab in preclinical models.
• The specific interaction between scFv S3 and R162 on EphA4 is crucial for its function.