1. Academic Validation
  2. STAT3 palmitoylation initiates a positive feedback loop that promotes the malignancy of hepatocellular carcinoma cells in mice

STAT3 palmitoylation initiates a positive feedback loop that promotes the malignancy of hepatocellular carcinoma cells in mice

  • Sci Signal. 2023 Dec 5;16(814):eadd2282. doi: 10.1126/scisignal.add2282.
Yi Jiang 1 Yuejie Xu 2 3 Chengliang Zhu 4 5 Guifang Xu 2 Lei Xu 2 Zijian Rao 4 Lixing Zhou 6 Ping Jiang 2 Sara Malik 7 Jingyuan Fang 1 Hening Lin 8 Mingming Zhang 1 8
Affiliations

Affiliations

  • 1 Division of Gastroenterology and Hepatology; Shanghai Institute of Digestive Disease; NHC Key Laboratory of Digestive Diseases; State Key Laboratory for Oncogenes and Related Genes; Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200001, China.
  • 2 Department of Gastroenterology, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing University, Nanjing 210008, China.
  • 3 Department of Traditional Chinese Medicine, Nanjing Drum Tower Hospital Clinical College of Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing 210046, China.
  • 4 Institute of Pharmacology and Toxicology, Zhejiang Province Key Laboratory of Anti-Cancer Drug Research, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, China.
  • 5 Center for Drug Safety Evaluation and Research of Zhejiang University, Zhejiang University, Hangzhou 310058, China.
  • 6 Center of Gerontology and Geriatrics, West China Hospital, Sichuan University, Chengdu, 610041, China.
  • 7 Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
  • 8 Howard Hughes Medical Institute; Department of Chemistry and Chemical Biology; Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
Abstract

Constitutive activation of the transcription factor STAT3 (signal transducer and activator of transcription 3) contributes to the malignancy of many cancers such as hepatocellular carcinoma (HCC) and is associated with poor prognosis. STAT3 activity is increased by the reversible palmitoylation of Cys108 by the palmitoyltransferase DHHC7 (encoded by ZDHHC7). Here, we investigated the consequences of S-palmitoylation of STAT3 in HCC. Increased ZDHHC7 abundance in HCC cases was associated with poor prognosis, as revealed by bioinformatics analysis of patient data. In HepG2 cells in vitro, DHHC7-mediated palmitoylation enhanced the expression of STAT3 target genes, including HIF1A, which encodes the hypoxia-inducible transcription factor HIF1α. Inhibiting DHHC7 decreased the S-palmitoylation of STAT3 and decreased HIF1α abundance. Furthermore, stabilization of HIF1α by cyclin-dependent kinase 5 (CDK5) enabled it to promote the expression of ZDHHC7, which generated a positive feedback loop between DHHC7, STAT3, and HIF1α. Perturbing this loop reduced the growth of HCC cells in vivo. Moreover, DHHC7, STAT3, and HIF1α were all abundant in human HCC tissues. Our study identifies a pathway connecting these proteins that is initiated by S-palmitoylation, which may be broadly applicable to understanding the role of this modification in Cancer.

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