Study on antibody therapeutics targeting lung cancer membrane

Abstract

Lung cancer is one of the most dangerous diseases to humanity which has the most mortality stake in cancer related death. The high mortality rate is due to the difficulty of early diagnosis and treatment of lung cancer. There are four types of lung cancers known as adenocarcinoma, small cell lung cancer, large cell lung cancer, squamous cell lung cancer, but current lung cancer treatments are limited to some types of lung cancers or the treatment is not effective enough. In this study, I developed a biomarker which detect all four types of lung cancer and used as a lung cancer therapy target. Cancer specific membrane proteins located outside of lung cancer cells can have a great advantage in diagnosis, and are also accessible when targeted for treatment. First, I analyzed the proteins from normal lung tissue and four types of lung cancer cells and selected the membrane proteins that only appear in lung cancer cells. After proteomic research, Dolichyl-diphosphooligosaccharide-Protein glycosyltransferase (DDOST) protein was selected as final as a lung cancer biomarker. Results with anti-DDOST antibody showed lung cancer specificity in all four types of lung cancer cell lines, and also cancer specific reaction in human lung tissues, indicating that DDOST can be an effective biomarker for all types of lung cancers. Treatment with anti-DDOST antibody showed complement-dependent cytotoxicity lung cancer cell lines, and tumor suppressing and targeting ability in animal lung cancer model. Next, I generated monoclonal antibody specific to the native structure of DDOST protein. Several antibody producing hybridoma clones were generated with recombinant DDOST protein antigen, and were tested through ELISA and immunocytochemistry selection. One of the native form DDOST targeting clones, DDOST-6D9 antibody showed strong signal in lung cancer cell immunocytochemistry. Also, DDOST-6D9 antibody showed lung cancer cell internalization which can be potential for therapeutic effect. Cell proliferation and migration assay showed that DDOST-6D9 antibody has anti-cancer effect in large cell lung cancer and squamous cell lung cancer cell. To evaluate antibody-mediated therapeutic effects, I made DDOST knock-down cell which produce DDOST gene targeting shRNA constantly. DDOST knock-down cell also had reduced cell proliferation and migration ability, indicating that DDOST-6D9 antibody work as inhibiting DDOST protein function. In conclusion, DDOST protein can be a promising biomarker for all four types of lung cancers and the internalizing monoclonal antibody targeting it, can work as a therapeutic treatment for squamous cell lung cancer and large cell lung cancer. Furthermore, study indicated that therapeutic effects of the antibody could be improved according to the target epitope.