1. Academic Validation
  2. Downregulation of RIG-I mediated by ITGB3/c-SRC/STAT3 signaling confers resistance to interferon-α-induced apoptosis in tumor-repopulating cells of melanoma

Downregulation of RIG-I mediated by ITGB3/c-SRC/STAT3 signaling confers resistance to interferon-α-induced apoptosis in tumor-repopulating cells of melanoma

  • J Immunother Cancer. 2020 Mar;8(1):e000111. doi: 10.1136/jitc-2019-000111.
Yong Li  # 1 Yingqiu Song  # 2 Pindong Li 2 Mingxing Li 3 Haizhou Wang 4 5 Tao Xu 1 Xiongjie Yu 1 Yuandong Yu 1 YunYan Tai 1 Ping Chen 1 Xiaojun Cai 1 Xianhe Wang 1 Longchao Xiang 1 Rui Deng 1 Xiufang Zhang 1 Liping Gao 1 Xuanbin Wang 1 6 Jing Liu 7 5 Fengjun Cao 8 9
Affiliations

Affiliations

  • 1 Department of Oncology, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei, China.
  • 2 Cancer Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
  • 3 Department of Rehabilitation Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
  • 4 Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China.
  • 5 Hubei Clinical Center & Key Lab of Intestinal & Colorectal Diseases, Wuhan, Hubei, China.
  • 6 Laboratory of Chinese Herbal Pharmacology, Oncology Center, Renmin Hospital, Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Shiyan, Hubei, China.
  • 7 Department of Gastroenterology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, China fengjuncao@hbmu.edu.cn liujing_GI@whu.edu.cn.
  • 8 Department of Oncology, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei, China fengjuncao@hbmu.edu.cn liujing_GI@whu.edu.cn.
  • 9 Institute of Cancer Research, Renmin Hospital, Hubei University of Medicine, Shiyan, Hubei, China.
  • # Contributed equally.
Abstract

Background: Interferon-α (IFN-α) plays a pivotal role in host antitumor immunity, and the evasion of IFN-α signaling pathway can lead to IFN-α resistance during the treatment of Cancer. Although the interplay between IFN-α and tumor cells has been extensively investigated in differentiated tumor cells, much less attention has been directed to tumor-repopulating cells (TRCs).

Methods: Three-dimentional soft fibrin matrix was used to select and grow highly malignant and tumorigenic melanoma TRCs. The regulation of Integrin β3 (ITGB3)-c-SRC-STAT signaling pathway in melanoma TRCs was investigated both in vitro and in vivo. The relevant mRNA and protein expression levels were analyzed by qRT-PCR and western blot analysis. Immunoprecipitation and chromatin immunoprecipitation (ChIP) followed by qPCR (ChIP-qPCR) assays were performed to detect protein-protein and protein-DNA interactions. The clinical impacts of retinoic acid inducible gene-I (RIG-I) were assessed in melanoma datasets obtained from The Cancer Genome Atlas and Gene Expression Omnibus profiles.

Results: IFN-α-induced Apoptosis was decreased in melanoma TRCs. Compared with conventional flask-cultured cells, IFN-α-mediated STAT1 activation was diminished in melanoma TRCs. Decreased expression of RIG-I in melanoma TRCs led to diminished activation of STAT1 via enhancing the interaction between Src homology region 2 domain-containing phosphatase-1 and STAT1. In addition, low expression levels of RIG-I correlated with poor prognosis in patients with melanoma. STAT3 was highly phosphorylated in TRCs and knockdown of STAT3 reversed the downregulation of RIG-I in TRCs. Knockdown of STAT3 resulted in STAT1 activation and increased expression of the pro-apoptosis genes in IFN-α-treated TRCs. Combined treatment of STAT3 Inhibitor and IFN-α increased the Apoptosis rate of TRCs. Disruption of ITGB3/c-SRC/STAT3 signaling pathway significantly elevated the efficiency of IFN-α-induced Apoptosis of TRCs.

Conclusions: In melanoma TRCs, ITGB3-c-SRC-STAT3 pathway caused RIG-I repression and then affect STAT1 activation to cause resistance to IFN-α-induced Apoptosis. RIG-I is a prognostic marker in patients with melanoma. Combination of STAT3 Inhibitor and IFN-α could enhance the efficacy of melanoma treatment. Our findings may provide a new concept of combinatorial treatment for future immunotherapy.

Keywords

immunology; medicine; tumours.

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