Anti-PEc: Development of a novel monoclonal antibody against prostate cancer

Background: The Ec peptide (PEc) that defines the IGF-1Ec isoform, is associated with prostate cancer progression by inducing proliferation, metastases, and tumour repair. On these grounds, an anti-PEc monoclonal antibody (MAb) was developed. Our objective is to examine the effects of this antibody on prostate cancer and its possible side effects. Methods: The effects of the obtained MAb were examined in cancer and non-cancerous cell lines (unmodified and modified either to overexpress or silence PEc) and in tumours in SCID mice injected with unmodified prostate cancer cells. The investigation was obtained with respect to cellular proliferation, migration, invasion, toxicity to tumours, effects on the cell cycle, immune response activation, effects on mesenchymal stem cell mobilisation leading to tumour repair, tissue distribution, and toxicity to mice. Results: Anti-PEc MAb treatment led to a significant decrease in cellular proliferation, migration, and invasion compared to the untreated cell lines (p < 0.0005 in every case). Mechanistically, these effects were associated with the downregulation of pERK1/2 and vimentin and the upregulation of E-Cadherin. In vivo, anti-PEc MAb treatment was associated with a significant decrease in tumour size and metastases rate (p < 0.0005 in every case) by reversing the tumours mesenchymal phenotype. It also inhibited host stem cell mobilisation towards the tumour, leading to apoptosis. Anti-PEc MAb assessment in respect to distribution and toxicity, indicated its tumour specificity and lack of toxicity. Conclusions: These data indicate that the therapeutic targeting of PEc with the anti-PEc MAb may have considerable clinical benefit for prostate cancer patients.