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Original research
Loss of ARID1A activates mTOR signaling and SOX9 in gastric adenocarcinoma—rationale for targeting ARID1A deficiency
  1. Xiaochuan Dong1,2,
  2. Shumei Song1,
  3. Yuan Li1,3,
  4. Yibo Fan1,
  5. Lulu Wang4,
  6. Ruiping Wang5,
  7. Longfei Huo1,
  8. Ailing Scott1,
  9. Yan Xu1,3,
  10. Melissa Pool Pizzi1,
  11. Lang Ma1,
  12. Ying Wang1,
  13. Jiangkang Jin1,
  14. Wei Zhao1,
  15. Xiaodan Yao1,
  16. Randy L Johnson6,
  17. Linghua Wang5,
  18. Zhenning Wang3,
  19. Guang Peng4,
  20. Jaffer A Ajani1
  1. 1Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
  2. 2Department of Pathology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
  3. 3Department of Surgical Oncology and General Surgery, The First Hospital of China Medical University, Shenyang, P.R.China
  4. 4Department of Clinical Cancer Prevention, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
  5. 5Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
  6. 6Department of Cancer Biology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
  1. Correspondence to Dr Shumei Song, Department of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA; ssong{at}mdanderson.org; Dr Jaffer A Ajani, Department of Gastrointestinal Medical Oncology, Unit 426, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Bouulevard, Houston, TX, USA, 77030-4009; jajani{at}mdanderson.org

Abstract

Background Gastric adenocarcinoma (GAC) is a lethal disease with limited therapeutic options. Genetic alterations in chromatin remodelling gene AT-rich interactive domain 1A (ARID1A) and mTOR pathway activation occur frequently in GAC. Targeting the mechanistic target of rapamycin (mTOR) pathway in unselected patients has failed to show survival benefit. A deeper understanding of GAC might identify a subset that can benefit from mTOR inhibition.

Methods Genomic alterations in ARID1A were analysed in GAC. Mouse gastric epithelial cells from CK19-Cre-Arid1Afl/fl and wild-type mice were used to determine the activation of oncogenic genes due to loss of Arid1A. Functional studies were performed to determine the significance of loss of ARID1A and the sensitivity of ARID1A-deficient cancer cells to mTOR inhibition in GAC.

Results More than 30% of GAC cases had alterations (mutations or deletions) of ARID1A and ARID1A expression was negatively associated with phosphorylation of S6 and SOX9 in GAC tissues and patient-derived xenografts (PDXs). Activation of mTOR signalling (increased pS6) and SOX9 nuclear expression were strongly increased in Arid1A−/− mouse gastric tissues which could be curtailed by RAD001, an mTOR inhibitor. Knockdown of ARID1A in GAC cell lines increased pS6 and nuclear SOX9 and increased sensitivity to an mTOR inhibitor which was further amplified by its combination with fluorouracil both in vitro and in vivo in PDXs.

Conclusions The loss of ARID1A activates pS6 and SOX9 in GAC, which can be effectively targeted by an mTOR inhibitor. Therefore, our studies suggest a new therapeutic strategy of clinically targeting the mTOR pathway in patients with GAC with ARID1A deficiency.

  • cancer
  • gastric cancer
  • gastric neoplasia
  • gastrointestinal cancer
  • gene expression

Data availability statement

Data are available upon reasonable request.

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Data availability statement

Data are available upon reasonable request.

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Footnotes

  • Contributors Conception and design: SS and JAA. Development of methodology: XD, SS, LH, YF, JJ and YL. Acquisition of data (provided animals, acquired and managed patients, provided facilities, etc): XD, YL, YF, YX, JJ, AS, WZ, LM, LW, XY, MPP and SS. Analysis and interpretation of data (eg, statistical analysis, biostatistics, computational analysis): SS, RW and LW. Writing, review, and/or revision of the manuscript: XD, SS, LH and JAA. Administrative, technical, or material support (ie, reporting or organising data, constructing databases): SS, XD, GP and RLJ. Study supervision: SS. Other (financial support): JAA and SS.

  • Funding This work was supported by Public Health Service Grant DF56338, which supports the Texas Medical Center Digestive Diseases Center (SS); The University of Texas MD Anderson Cancer Center Institutional Research Grant (3-0026317, SS); U.S. Department of Defense grants CA160433, CA170906(SS); and and National Institutes of Health/National Cancer Institute grants CA129906, CA138671, and CA172741 (JAA). This work was also supported by the NIH/NCI under award number P30CA016672 and under award number P30CA016672 for MDACC core facilities.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Please add Dr. Jaffer A Ajani's ORCID ID: 0000-0001-9946-0629; and adding: Dr. Guang Peng's ORCID ID: 0000-0002-4392-1497 thanks.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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