ALKBH5 Drives Immune Suppression Via Targeting AXIN2 to Promote Colorectal Cancer and Is a Target for Boosting Immunotherapy

Jianning Zhai; Huarong Chen; Chi Chun Wong; Yao Peng; Hongyan Gou; Jingwan Zhang; Yasi Pan; Danyu Chen; Yufeng Lin; Shiyan Wang; Wei Kang; Ka Fai To; Zhiwei Chen; Yuqiang Nie; Housheng Hansen He; Joseph Jao-Yiu Sung; Jun Yu

doi:10.1053/j.gastro.2023.04.032

ALKBH5 Drives Immune Suppression Via Targeting AXIN2 to Promote Colorectal Cancer and Is a Target for Boosting Immunotherapy

Gastroenterology. 2023 Aug;165(2):445-462. doi: 10.1053/j.gastro.2023.04.032. Epub 2023 May 9.

Authors

Jianning Zhai¹, Huarong Chen², Chi Chun Wong¹, Yao Peng³, Hongyan Gou¹, Jingwan Zhang¹, Yasi Pan¹, Danyu Chen¹, Yufeng Lin¹, Shiyan Wang⁴, Wei Kang⁵, Ka Fai To⁵, Zhiwei Chen⁶, Yuqiang Nie⁷, Housheng Hansen He⁴, Joseph Jao-Yiu Sung⁸, Jun Yu⁹

Affiliations

¹ Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong.
² Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong; Department of Anesthesia and Intensive Care and Peter Hung Pain Research Institute, The Chinese University of Hong Kong, Hong Kong.
³ Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong; Department of Gastroenterology, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, China.
⁴ Princess Margaret Cancer Centre, University Health Network, Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
⁵ Department of Anatomical and Cellular Pathology, State Key Laboratory of Oncology in South China, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong.
⁶ AIDS Institute and Department of Microbiology, State Key Laboratory of Emerging Infectious Disease, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong.
⁷ Department of Gastroenterology, Guangzhou First People's Hospital, Guangzhou Medical University, Guangzhou, China.
⁸ Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong; Lee Kong Chian School of Medicine, Nanyang Technology University, Singapore.
⁹ Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong-Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong. Electronic address: junyu@cuhk.edu.hk.

PMID: 37169182
DOI: 10.1053/j.gastro.2023.04.032

Abstract

Background & aims: Immune checkpoint blockade therapy benefits only a small subset of patients with colorectal cancer (CRC), and identification of CRC-intrinsic events modulating immune checkpoint blockade efficacy is an unmet need. We found that AlkB homolog 5 (ALKBH5), an RNA N⁶-methyladenosine eraser, drives immunosuppression and is a molecular target to boost immune checkpoint blockade therapy in CRC.

Methods: Clinical significance of ALKBH5 was evaluated in human samples (n = 205). Function of ALKBH5 was investigated in allografts, CD34⁺ humanized mice, and Alkbh5 knockin mice. Immunity change was determined by means of flow cytometry, immunofluorescence, and functional investigation. Methylated RNA immunoprecipitation sequencing and RNA sequencing were used to identify ALKBH5 targets. Vesicle-like nanoparticle-encapsulated ALKBH5-small interfering RNA was constructed for targeting ALKBH5 in vivo.

Results: High ALKBH5 expression predicts poor prognosis in CRC. ALKBH5 induced myeloid-derived suppressor cell accumulation but reduced natural killer cells and cytotoxic CD8⁺ T cells to induce colorectal tumorigenesis in allografts, CD34⁺ humanized mice, and intestine-specific Alkbh5 knockin mice. Mechanistically, AXIN2, a Wnt suppressor, was identified as a target of ALKBH5. ALKBH5 binds and demethylates AXIN2 messenger RNA, which caused its dissociation from N⁶-methyladenosine reader IGF2BP1 and degradation, resulting in hyperactivated Wnt/β-catenin. Subsequently, Wnt/β-catenin targets, including Dickkopf-related protein 1 (DKK1) were induced by ALKBH5. ALKBH5-induced DKK1 recruited myeloid-derived suppressor cells to drive immunosuppression in CRC, and this effect was abolished by anti-DKK1 in vitro and in vivo. Finally, vesicle-like nanoparticle-encapsulated ALKBH5-small interfering RNA, or anti-DKK1 potentiated anti-PD1 treatment in suppressing CRC growth by enhancing antitumor immunity.

Conclusions: This study identified an ALKBH5-N⁶-methyladenosine-AXIN2-Wnt-DKK1 axis in CRC, which drives immune suppression to facilitate tumorigenesis. Targeting of ALKBH5 is a promising strategy for sensitizing CRC to immunotherapy.

Keywords: Colorectal Cancer; DKK1; MDSCs; Wnt/β-Catenin Signaling; m(6)A Modification.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

AlkB Homolog 5, RNA Demethylase / genetics
AlkB Homolog 5, RNA Demethylase / metabolism
Animals
Axin Protein
CD8-Positive T-Lymphocytes / metabolism
Carcinogenesis / genetics
Cell Transformation, Neoplastic
Colorectal Neoplasms* / drug therapy
Colorectal Neoplasms* / therapy
Humans
Immune Checkpoint Inhibitors / therapeutic use
Immunosuppression Therapy
Immunotherapy
Mice
RNA, Small Interfering / metabolism
beta Catenin* / genetics
beta Catenin* / metabolism

Substances

beta Catenin
Immune Checkpoint Inhibitors
RNA, Small Interfering
AXIN2 protein, human
Axin Protein
ALKBH5 protein, human
AlkB Homolog 5, RNA Demethylase