BET protein inhibition evidently enhances sensitivity to PI3K/mTOR dual inhibition in intrahepatic cholangiocarcinoma

Xiaolong Miao,Yuancong Jiang,Xinyi Wang,Deqiang Kong,Xuhang Zhu,Chen Liu,Xing Yu,Rui Tian,Yao Wang,Zelai Wu,Weihua Gong

doi:10.1038/s41419-021-04305-3

Abstract

Intrahepatic cholangiocarcinoma (ICC), the second most common primary liver cancer, is a fatal malignancy with a poor prognosis and only very limited therapeutic options. Although molecular targeted therapy is emerged as a promising treatment strategy, resistance to molecular-targeted therapy occurs inevitably, which represents a major clinical challenge. In this study, we confirmed that mammalian target of rapamycin (mTOR) signaling is the most significantly affected pathways in ICC. As a novel phosphoinositide 3-kinase (PI3K)/mTOR dual inhibitor, BEZ235, exerts antitumour activity by effectively and specifically blocking the dysfunctional activation of the PI3K/serine/threonine kinase (AKT)/mTOR pathway. We generate the orthotopic ICC mouse model through hydrodynamic transfection of AKT and yes-associated protein (YAP) plasmids into the mouse liver. Our study confirmed that BEZ235 can suppress the proliferation, invasion and colony conformation abilities of ICC cells in vitro but cannot effectively inhibit ICC progression in vivo. Inhibition of PI3K/mTOR allowed upregulation of c-Myc and YAP through suppressed the phosphorylation of LATS1. It would be a novel mechanism that mediated resistance to PI3K/mTOR dual inhibitor. However, Bromo- and extraterminal domain (BET) inhibition by JQ1 downregulates c-Myc and YAP transcription, which could enhance the efficacy of PI3K/mTOR inhibitors. The efficacy results of combination therapy exhibited effective treatment on ICC in vitro and in vivo. Our data further confirmed that the combination of PI3K/mTOR dual inhibitor and BET inhibition induces M1 polarization and suppresses M2 polarization in macrophages by regulating the expression of HIF-1α. Our study provides a novel and efficient therapeutic strategy in treating primary ICC.

Highlights

Cholangiocarcinoma (CCA) is a heterogeneous group of cancers with pathologic features of intra- or extrahepatic biliary tract differentiation [1]
Previous evidence indicated that Nitidine chloride yes-associated protein (YAP) and c-Myc mediated resistance to the phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) dual treatment significantly enhanced the level of p-LATS1 in cancer inhibitor cells
In vivo, we found that the demonstrate the same conclusion by transwell assays (Suppleexpression levels of YAP and c-Myc were increased in the BEZ235 mental Figs. 2B and 3B)

Summary

INTRODUCTION

Cholangiocarcinoma (CCA) is a heterogeneous group of cancers with pathologic features of intra- or extrahepatic biliary tract differentiation [1]. CCK-8 assays showed a similar result delivered plasmids (AKT/YAP S127A) for sleeping beauty transposase to the EdU assay: BEZ235 significantly inhibited RBE cell via hydrodynamic injection to generate the ICC model. The phosphorylation of LATS1 inhibits YAP/TAZ, The PI3K/mTOR dual inhibitor increased c-Myc and YAP which is the main effector of the Hippo pathway [21]. MYC and YAP expression in BEZ235-treated RBE cells by RNA-seq This is a novel mechanism by which BEZ235 upregulates c-Myc analysis (Fig. 3A). Previous evidence indicated that Nitidine chloride YAP and c-Myc mediated resistance to the PI3K/mTOR dual treatment significantly enhanced the level of p-LATS1 in cancer inhibitor cells. The levels of p-LATS1 was markedly increased in response to RBE cells were transfected with YAP or c-Myc plasmids to Nitidine chloride treatment (Supplemental Fig. 4A).

DISCUSSION

Miao et al 7

METHODS AND MATERIALS

Findings

ETHICS STATEMENT