Page 2 - I. Chemical biology and drug discovery

[I. Chemical biology and drug discovery-1]

Target deconvolution using label-free method of autophagy

inhibitor and its antitumor activity in glioblastoma

Hui-Yun Hwang¹˙#, Yoon Sun Cho¹, Eun Ji Gwak¹, Jin Young Kim², Ki Na Yun², Jong Shin Yoo²,
Eunhyeong Lee³, Injune Kim³, György Marko-Varga¹˙⁴, Ho Jeong Kwon¹˙*

¹Department of Biotechnology, College of Life Science & Biotechnology, Yonsei University, Seoul 120-749, Korea,
²Biomedical Omics Group, Korea Basic Science Institute, Chungbuk 28119, Korea, ³Graduate School of Medical

Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea, ⁴Clinical

Protein Science & Imaging, Department of Biomedical Engineering, Lund University, Lund SE-221 84, Sweden

Manipulating autophagy is a promising strategy for treating cancer as several autophagy inhibitors are 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 used 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 Hsp70 as a key target protein of unmodified APZ in autophagy.
Either APZ treatment or Hsp70 inhibition attenuates integrity of lysosomes, which leads to autophagic cell death

exhibiting an excellent synergism with a clinical drug, temozolomide, in vitro, in vivo, and orthotropic glioma
xenograft model. These findings demonstrate the potential of APZ to induce autophagic cell death and its

development to combinational chemotherapeutic agent for glioma treatment. Collectively, our study demonstrated
that APZ, a new autophagy inhibitor, can be used as a potent antitumor drug candidate to get over unassailable

glioma and revealed a novel function of Hsp70 in lysosomal integrity regulation of autophagy.