A high‐throughput RNAi screen for detection of immune‐checkpoint molecules that mediate tumor resistance to cytotoxic T lymphocytes

EMBO Molecular Medicine

Nisit Khandelwal²  Marco Breinig⁴  Tobias Speck²  Tillmann Michels²  Christiane Kreutzer⁵  Antonio Sorrentino²  Ashwini Kumar Sharma¹  Ludmila Umansky²  Heinke Conrad⁵  Isabel Poschke⁶  Rienk Offringa⁶  Rainer König¹  Helga Bernhard⁷  Arthur Machlenkin³  Michael Boutros⁴ 

[1] Division of Theoretical Bioinformatics, German Cancer Research Center (DKFZ), Heidelberg, Germany;Division of Translational Immunology, German Cancer Research Center (DKFZ), Heidelberg, Germany;Sharett Institute of Oncology, Hadassah-Hebrew University Hospital, Jerusalem, Israel;Division of Signaling and Functional Genomics, German Cancer Research Center (DKFZ), Heidelberg, Germany;Division of Immunogenetics, German Cancer Research Center (DKFZ), Heidelberg, Germany;Department of Molecular Oncology of Gastrointestinal Tumors, German Cancer Research Center (DKFZ) and Division of Pancreas Carcinoma Research, Surgery Clinic of Heidelberg University, Heidelberg, Germany;Department of Hematology/Oncology, Klinikum Darmstadt GmbH, Darmstadt, Germany

关键词: cancer immunotherapy;    immune suppression;    RNAi screen;   

DOI  :  10.15252/emmm.201404414

来源: Wiley

【 摘 要 】

Abstract

The success of T cell-based cancer immunotherapy is limited by tumor's resistance against killing by cytotoxic T lymphocytes (CTLs). Tumor-immune resistance is mediated by cell surface ligands that engage immune-inhibitory receptors on T cells. These ligands represent potent targets for therapeutic inhibition. So far, only few immune-suppressive ligands have been identified. We here describe a rapid high-throughput siRNA-based screening approach that allows a comprehensive identification of ligands on human cancer cells that inhibit CTL-mediated tumor cell killing. We exemplarily demonstrate that CCR9, which is expressed in many cancers, exerts strong immune-regulatory effects on T cell responses in multiple tumors. Unlike PDL1, which inhibits TCR signaling, CCR9 regulates STAT signaling in T cells, resulting in reduced T-helper-1 cytokine secretion and reduced cytotoxic capacity. Moreover, inhibition of CCR9 expression on tumor cells facilitated immunotherapy of human tumors by tumor-specific T cells in vivo. Taken together, this method allows a rapid and comprehensive determination of immune-modulatory genes in human tumors which, as an entity, represent the ‘immune modulatome’ of cancer.

Synopsis

A novel in vitro screening methodology involving high-throughput RNAi-based gene knockdown in short-term cocultures identifies immune-modulatory molecules that mediate tumor resistance to cytotoxic T cells.

• Breast cancer cells express on their surface multiple molecules that inhibit T cell-mediated tumor cell killing
• CCR9 strongly inhibits the destruction of breast cancer, as well as melanoma and pancreatic cancer, by tumor-specific cytotoxic T cells
• CCR9 directly inhibits T cell function in a cell–cell contact-dependent manner
• CCR9 engagement by T cells modulates effector cytokine secretion through the regulation of STAT pathway activation
• CCR9 knockdown in melanoma cells results in efficient rejection of xenotransplanted melanoma tumors in vivo

【 授权许可】

CC BY   
© 2015 The Authors. Published under the terms of the CC BY 4.0 license

Creative Commons Attribution 4.0 License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.