PBRM1 and the glycosylphosphatidylinositol biosynthetic pathway promote tumor killing mediated by MHC-unrestricted cytotoxic lymphocytes.

Abstract

Major histocompatibility complex (MHC)-unrestricted cytotoxic lymphocytes (CLs) such as natural killer (NK) cells can detect and destroy tumor and virus-infected cells resistant to T cell-mediated killing. Here, we performed genome-wide genetic screens to identify tumor-intrinsic genes regulating killing by MHC-unrestricted CLs. A group of genes identified in our screens encode enzymes for the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor, which is not involved in tumor response to T cell<b>-</b>mediated cytotoxicity. Another gene identified in the screens was <i>PBRM1</i>, which encodes a subunit of the PBAF form of the SWI/SNF chromatin-remodeling complex. <i>PBRM1</i> mutations in tumor cells cause resistance to MHC-unrestricted killing, in contrast to their sensitizing effects on T cell<b>-</b>mediated killing. PBRM1 and the GPI biosynthetic pathway regulate the ligands of NK cell receptors in tumor cells and promote cytolytic granule secretion in CLs. The regulators identified in this work represent potential targets for cancer immunotherapy.