Abstract 2389: Role of Midkine in molecular targeted therapy to TIP1 for lung cancer treatment

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Abstract Non-small cell lung cancer (NSCLC) ranks among the highest cancer-related mortalities world-wide. Targeted therapy has been a growing topic of investigation to improve therapeutic efficacy for NSCLC. A few targeted therapies that exploit aberrant protein expression profiles have been approved for NSCLC. However, marginal improvement in efficacy observed with these therapeutic approaches highlights the need for discovery of additional therapeutic targets. We identified Tax interacting protein 1 (TIP1) which is overexpressed in various cancers as a molecular targets. We focused on antibody-based targeting of the chaperone protein TIP1. The functional domain of TIP1 (PDZ domain) caps the C-terminus of many cellular proteins that regulate important cellular functions. Knocking down TIP1 revealed that it plays an important role in cell signaling, cancer development, and progression. Comparing antibodies targeting different epitopes of TIP1, we found that antibodies against the PDZ domain of TIP1 were most effective in inducing cytotoxicity of lung cancer cells but not normal cells. Anti-PDZ/TIP1 antibodies injected into mice bearing lung cancer bind specifically to cancer and substantially enhance tumor control. A mass spectrometry-based approach identified Midkine (MDK) as a putative protein that modulates this cytotoxicity by anti-TIP1 antibodies. Additional studies suggested that the β-catenin/Wnt signaling may be involved in induction of MDK after blocking of TIP1. These studies led to the hypothesis that MDK is upregulated by the anti-PDZ/TIP1 antibody via the β-catenin/Wnt signaling pathway, which subsequently modulates downstream signaling mechanisms. This project will systematically characterize the mechanisms of cytotoxicity by the anti-PDZ/TIP1 antibodies. To achieve this, a number of novel methodologies including genome-wide CRISPR knockout, proteomics and mass cytometry to characterize the link between TIP1 and MDK will be applied. The project will guide development of combination therapies to optimize efficacy of NSCLC treatment. One strategy proposed, is dual-targeting of TIP1 and MDK for enhanced efficacy. This project will lead to identification of novel molecular targets for NSCLC treatment that have never been considered before. Citation Format: Vaishali Kapoor, Abhay K. Singh, Dinesh Thotala, Dennis Hallahan. Role of Midkine in molecular targeted therapy to TIP1 for lung cancer treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2389.