CAGE Binds to Beclin1, Regulates Autophagic Flux and CAGE-Derived Peptide Confers Sensitivity to Anti-cancer Drugs in Non-small Cell Lung Cancer Cells.

Minjeong Yeon,Hyun Suk Jung,Dooil Jeoung,Misun Kim,Doyong Jeon,Jaewhan Byun,Youngmi Kim,Hyuna Kim

doi:10.3389/fonc.2018.00599

Minjeong Yeon, Hyun Suk Jung + Show 6 more

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https://doi.org/10.3389/fonc.2018.00599

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Abstract

The objective of this study was to determine the role of CAGE, a cancer/testis antigen, in resistance of non-small cell lung cancers to anti-cancer drugs. Erlotinib-resistant PC-9 cells (PC-9/ER) with EGFR mutations (ex 19 del + T790M of EGFR), showed higher level of autophagic flux than parental sensitive PC-9 cells. Erlotinib and osimertinib increased autophagic flux and induced the binding of CAGE to Beclin1 in PC-9 cells. The inhibition or induction of autophagy regulated the binding of CAGE to Beclin1 and the responses to anti-cancer drugs. CAGE showed binding to HER2 while HER2 was necessary for binding of CAGE to Beclin1. CAGE was responsible for high level of autophagic flux and resistance to anti-cancer drugs in PC-9/ER cells. A peptide corresponding to the DEAD box domain of CAGE, 266AQTGTGKT273, enhanced the sensitivity of PC-9/ER cells to erlotinib and osimertinib, inhibited the binding of CAGE to Beclin1 and regulated autophagic flux in PC-9/ER cells. Mutant CAGE-derived peptide 266AQTGTGAT273 or 266AQTGTGKA273 did not affect autophagic flux or the binding of CAGE to Beclin1. AQTGTGKT peptide showed binding to CAGE, but not to Beclin1. FITC-AQTGTGKT peptide showed co-localization with CAGE. AQTGTGKT peptide decreased tumorigenic potentials of PC-9/ER and H1975 cells, non-small cell lung cancer (NSCLC) cells with EGFR mutation (L885R/T790M), by inhibiting autophagic fluxand inhibiting the binding of CAGE to Beclin1. AQTGTGKT peptide also enhanced the sensitivity of H1975 cells to anti-cancer drugs. AQTGTGKT peptide showed tumor homing potential based on ex vivo homing assays of xenograft of H1975 cells. AQTGTGKT peptide restored expression levels of miR-143-3p and miR-373-5p, decreased autophagic flux and conferred sensitivity to anti-cancer drugs. These results present evidence that combination of anti-cancer drug with CAGE-derived peptide could overcome resistance of non-small cell lung cancers to anti-cancer drugs.

Highlights

CAGE, a cancer/testis antigen, shows wide expression among tumor tissues while its expression is limited to testis among normal tissues [1]
We found that CAGE could regulate autophagic flux and responses to anti-cancer drugs in non-small cell lung cancer cells with EGFR mutations such as PC-9/ER cells and H1975 cells
Our results revealed that PC-9/ER cells had higher levels of autophagic flux than PC-9 parental anti-cancer drug-sensitive non-small cell lung cancer cells (Figure 1C)

Summary

Introduction

CAGE, a cancer/testis antigen, shows wide expression among tumor tissues while its expression is limited to testis among normal tissues [1]. CAGE is present in the sera of patients with various cancers [1, 2]. CAGE possesses oncogenic potential and promotes cell cycle progression by inducing AP-1- and E2F-dependent expression of cyclins D1 and E [6]. It stimulates angiogenesis [7, 8], binds to HDAC2 and confers resistance to anti-cancer drugs in various cancer cells [9]. Histone deacetylase-3 directly regulates the expression of CAGE and pEGFRY845 to confer sensitivity to anticancer drugs [10]. Peptides corresponding to the DEAD box helicase domain of CAGE such as AQTGTGKT shows anti-cancer activity by preventing CAGE from binding to GSK3β [11]

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