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Proteasome inhibitor interacts synergistically with autophagy inhibitor to suppress proliferation and induce apoptosis in hepatocellular carcinoma
Author(s) -
Hui Bo,
Shi YingHong,
Ding ZhenBin,
Zhou Jian,
Gu ChengYu,
Peng YuanFei,
Yang Hua,
Liu WeiRen,
Shi GuoMing,
Fan Jia
Publication year - 2012
Publication title -
cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.052
H-Index - 304
eISSN - 1097-0142
pISSN - 0008-543X
DOI - 10.1002/cncr.27586
Subject(s) - autophagy , propidium iodide , bortezomib , apoptosis , proteasome inhibitor , proteasome , cell growth , cancer research , tunel assay , programmed cell death , microbiology and biotechnology , biology , chemistry , immunology , biochemistry , multiple myeloma
BACKGROUND: The ubiquitin‐proteasome system and autophagy‐lysosome system are 2 major protein degradation pathways in eukaryotic cells, which are tightly linked to cancer. Proteasome inhibitors have been approved in clinical use against hematologic malignancies, but their application in solid tumors is uncertain. Moreover, the role of autophagy after proteasome inhibition is controversial. METHODS: Two proteasome inhibitors, 2 autophagy inhibitors, and 3 hepatocellular carcinoma (HCC) cell lines were investigated in the current study. In vitro, cell proliferation was evaluated by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assay, cell apoptosis was evaluated by flow cytometry analysis of annexin‐V/propidium iodide staining, and autophagy was evaluated by green fluorescent protein‐light chain 3 (GFP‐LC3) redistribution and LC3 Western blot analysis. In vivo, Ki‐67 staining was used to detect cell proliferation, terminal deoxynucleotidyl transferase‐mediated deoxyuridine triphosphate nick‐end labeling (TUNEL) staining was used to detect apoptosis, and electron microscopy and p62 immunohistochemical staining were used to detect autophagy. RESULTS: Proteasome inhibitors suppressed proliferation, induced apoptosis, and activated autophagy in HCC cell lines in vitro, and autophagy exerted a protective role after proteasome inhibition. In vivo, anticancer effects of bortezomib on the MHCC‐97H orthotopic model (human HCC cells) were different from the effects observed on the Huh‐7 subcutaneous model (human HCC cells). The autophagy inhibitor chloroquine interacted synergistically with bortezomib to suppress proliferation and induce apoptosis in both tumor models. CONCLUSIONS: The current results indicated that simultaneous targeting of the proteasome and autophagy pathways may represent a promising method for HCC treatment. Cancer 2012. © 2012 American Cancer Society.