Poster Presentation HUPO 2019 - 18th Human Proteome Organization World Congress

Quantitative proteomics analysis using label-free DARTS and LC-MS/MS method reveals a target protein of cancer therapeutic small molecule (#586)

Hui-Yun Hwang 1 , Yoon Sun Cho 1 , Jin Young Kim 2 , Ki Na Yun 2 , Jong Shin Yoo 2 , Eun hyeong Lee 3 , In june Kim 3 , Gy├Ârgy Marko-Varga 1 4 , Ho Jeong Kwon 1
  1. Chemical Genomics Global Research Laboratory, Department of Biotechnology, Yonsei University, Seoul, South Korea
  2. Biomedical Omics Group, Korea Basic Science Institute, Chungbuk, South Korea
  3. Biomedical Science and Engineering Interdisciplinary Program, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
  4. Clinical Protein Science & Imaging, Department of Biomedical Engineering, Lund University, Lund, Sweden

Manipulating autophagy is a promising strategy for treating cancer with several autophagy inhibitors shown to induce autophagic cell death. One of these, autophagonizer (APZ), induces apoptosis-independent cell death by binding an unknown target via an unknown mechanism. To identify APZ targets we developed a label-free drug affinity responsive target stability (DARTS) approach with a liquid chromatography/tandem mass spectrometry (LC-MS/MS) readout. Of 35 protein interactors, we identified APZBP as a key target protein of unmodified APZ in autophagy. Additionally, sequence coverage analysis in DARTS LC-MS proteome revealed that specific peptide fragments in the nucleotide binding domain (NBD, ATPase domain) of APZBP were protected by APZ in the pronase-treated proteome. APZBP inhibition through siRNA knockdown or by a specific inhibitor, inhibited autophagy in HeLa cells similar to APZ treatment, whereas APZBP overexpression overcame inhibition induced by APZ. Additionally, APZ exhibited significant synergism with TMZ (temozolomide), which has been used for chemotherapeutic agent of glioblastoma, in vitro and orthotopic mouse model. These findings demonstrate the potential of APZ to induce autophagic cell death and its development as a potent anticancer drug. Our study showed that combined DARTS and LC-MS/MS-based target identification of non-tagging bioactive small molecule of interest is effective for novel protein target identification and revealed a novel function for APZBP as cancer therapeutic target.