Deubiquitinase USP7-mediated MCL-1 up-regulation enhances arsenic and benzo(a)pyrene co-exposure-induced cancer stem cell-like property and tumorigenesis

Ping Yang, Jie Xie, Yunfei Li, Hsuan Pei Lin, William Fenske, Marco Clementino, Yiguo Jiang, Chengfeng Yang, Zhishan Wang

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Rationale: MCL-1 is up-regulated in cancer and a target for cancer treatment. How MCL-1 is up-regulated and whether MCL-1 up-regulation plays a role in tumorigenic process is not well-known. Arsenic and benzo(a)pyrene (BaP) are well-recognized lung carcinogens and we recently reported that arsenic and BaP co-exposure acts synergistically in inducing cancer stem cell (CSC)-like property and lung tumorigenesis. This study was performed to further investigate the underlying mechanism focusing on the role of MCL-1. Methods: The spheroid formation assay and nude mouse tumorigenesis assay were used to determine the CSC-like property and tumorigenicity of arsenic plus BaP co-exposure-transformed human bronchial epithelial BEAS-2B cells, respectively. Biochemical, pharmacological and genetic approaches were used to manipulate gene expressions, dissect signaling pathways and determine protein-protein interactions. Both loss-of-function and gain-of-function approaches were used to validate the role of MCL-1 in arsenic plus BaP co-exposure-enhanced CSC-like property and tumorigenicity. Results: Arsenic plus BaP co-exposure-transformed cells express significantly higher protein levels of MCL-1 than the passage-matched control, arsenic or BaP exposure alone-transformed cells. Knocking down MCL-1 levels in arsenic plus BaP co-exposure-transformed cells significantly reduced their apoptosis resistance, CSC-like property and tumorigenicity in mice. Mechanistic studies revealed that arsenic plus BaP co-exposure up-regulates MCL-1 protein levels by synergistically activating the PI3K/Akt/mTOR pathway to increase the level of a deubiquitinase USP7, which in turn reduces the level of MCL-1 protein ubiquitination and prevents its subsequent proteasome degradation. Conclusions: The deubiquitinase USP7-mediated MCL-1 up-regulation enhances arsenic and BaP co-exposure-induced CSC-like property and tumorigenesis, providing the first evidence demonstrating that USP7 stabilizes MCL-1 protein during the tumorigenic process.

Original languageEnglish
Pages (from-to)9050-9065
Number of pages16
Issue number20
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© The author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License ( See for full terms and conditions.


  • Arsenic
  • Benzo(a)pyrene
  • Cancer stem cell-like property
  • MCL-1
  • USP7

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Pharmacology, Toxicology and Pharmaceutics (miscellaneous)


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