PMID- 34987649 OWN - NLM STAT- MEDLINE DCOM- 20220307 LR - 20220716 IS - 1838-7640 (Electronic) IS - 1838-7640 (Linking) VI - 12 IP - 1 DP - 2022 TI - Targeting protumor factor chitinase-3-like-1 secreted by Rab37 vesicles for cancer immunotherapy. PG - 340-361 LID - 10.7150/thno.65522 [doi] AB - Background: Chitinase 3-like-1 (CHI3L1) is a secretion glycoprotein associated with the immunosuppressive tumor microenvironment (TME). The secretory mode of CHI3L1 makes it a promising target for cancer treatment. We have previously reported that Rab37 small GTPase mediates secretion of IL-6 in macrophages to promote cancer progression, whereas the roles of Rab37 in the intracellular trafficking and exocytosis of CHI3L1 are unclear. Methods: We examined the concentration of CHI3L1 in the culture medium of splenocytes and bone marrow derived macrophages (BMDMs) from wild-type or Rab37 knockout mice, and macrophage or T cell lines expressing wild type, active GTP-bound or inactive GDP-bound Rab37. Vesicle isolation, total internal reflection fluorescence microscopy, and real-time confocal microscopy were conducted. We developed polyclonal neutralizing-CHI3L1 antibodies (nCHI3L1 Abs) to validate the therapeutic efficacy in orthotopic lung, pancreas and colon cancer allograft models. Multiplex fluorescence immunohistochemistry was performed to detect the protein level of Rab37 and CHI3L1, and localization of the tumor-infiltrating immune cells in allografts from mice or tumor specimens from cancer patients. Results: We demonstrate a novel secretion mode of CHI3L1 mediated by the small GTPase Rab37 in T cells and macrophages. Rab37 mediated CHI3L1 intracellular vesicle trafficking and exocytosis in a GTP-dependent manner, which is abolished in the splenocytes and BMDMs from Rab37 knockout mice and attenuated in macrophage or T cell lines expressing the inactive Rab37. The secreted CHI3L1 activated AKT, ss-catenin and NF-kappaB signal pathways in cancer cells and macrophages to foster a protumor TME characterized by activating M2 macrophages and increasing the population of regulatory T cells. Our developed nCHI3L1 Abs showed the dual properties of reducing tumor growth/metastases and eliciting an immunostimulatory TME in syngeneic orthotopic lung, pancreas and colon tumor models. Clinically, high plasma level or intratumoral expression of CHI3L1 correlated with poor survival in 161 lung cancer, 155 pancreatic cancer and 180 colon cancer patients. Conclusions: These results provide the first evidence that Rab37 mediates CHI3L1 secretion in immune cells and highlight nCHI3L1 Abs that can simultaneously target both cancer cells and tumor microenvironment. CI - (c) The author(s). FAU - Yang, Pei-Shan AU - Yang PS AD - Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Yu, Min-Hua AU - Yu MH AD - Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Hou, Ya-Chin AU - Hou YC AD - Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan. AD - Department of Clinical Medical Research, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Chang, Chih-Peng AU - Chang CP AD - Department of Microbiology and Immunology, College of Medicine, National Cheng Kung University, Tainan, Taiwan. AD - Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Lin, Shao-Chieh AU - Lin SC AD - Colorectal Division, Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Kuo, I-Ying AU - Kuo IY AD - Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan. AD - Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Su, Pei-Chia AU - Su PC AD - Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Cheng, Hung-Chi AU - Cheng HC AD - Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Su, Wu-Chou AU - Su WC AD - Division of Oncology, Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Shan, Yan-Shen AU - Shan YS AD - Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan. AD - Department of Clinical Medical Research, College of Medicine, National Cheng Kung University, Tainan, Taiwan. AD - Division of General Surgery, Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan. FAU - Wang, Yi-Ching AU - Wang YC AD - Department of Pharmacology, College of Medicine, National Cheng Kung University, Tainan, Taiwan. AD - Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan. LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20220101 PL - Australia TA - Theranostics JT - Theranostics JID - 101552395 RN - 0 (CHI3L1 protein, human) RN - 0 (Chitinase-3-Like Protein 1) RN - EC 3.6.1.- (Rab37 protein, human) RN - EC 3.6.5.2 (rab GTP-Binding Proteins) SB - IM MH - Animals MH - Cell Line, Tumor MH - Chitinase-3-Like Protein 1/*immunology MH - Cohort Studies MH - Gene Expression Regulation, Neoplastic MH - Immunotherapy/*methods MH - Mice MH - Mice, Knockout MH - *Neoplasms/immunology/therapy MH - Tumor Microenvironment MH - rab GTP-Binding Proteins/*immunology PMC - PMC8690922 OTO - NOTNLM OT - Rab37 OT - chitinase 3-like-1 OT - exocytosis OT - neutralizing antibody OT - tumor microenvironment COIS- Competing Interests: The authors have declared that no competing interest exists. EDAT- 2022/01/07 06:00 MHDA- 2022/03/08 06:00 PMCR- 2022/01/01 CRDT- 2022/01/06 05:55 PHST- 2021/07/30 00:00 [received] PHST- 2021/10/26 00:00 [accepted] PHST- 2022/01/06 05:55 [entrez] PHST- 2022/01/07 06:00 [pubmed] PHST- 2022/03/08 06:00 [medline] PHST- 2022/01/01 00:00 [pmc-release] AID - thnov12p0340 [pii] AID - 10.7150/thno.65522 [doi] PST - epublish SO - Theranostics. 2022 Jan 1;12(1):340-361. doi: 10.7150/thno.65522. eCollection 2022.