Investigating the influence of phospholipases onimmune evasion

Abstract public domain (NIH RePORTER)

PROJECT SUMMARY/ABSTRACT Cancer development and progression relies on genetic and epigenetic perturbations that disrupt normal tumor suppressive mechanisms. One such mechanism is immune surveillance, in which the immune system can detect and destroy malignant cells. Studies characterizing how certain tumors bypass immune surveillance have led to advances in immunotherapy, including immune checkpoint blockade (ICB) and chimeric antigen receptor (CAR) T cell therapy. However, only a subset of patients qualify for these therapies, and a number of those who undergo treatment fail to respond, suggesting that a complete understanding of immune evasion mechanisms remains elusive. Study of this phenomenon is further complicated by the genetic heterogeneity of cancer; each tumor contains a unique combination of germline and somatic variants that may have the potential to influence tumor-immune interactions. The central hypothesis of this proposal is that context- dependent somatic variation observed within cancer patients contributes to immune evasion and immunotherapy failure. An in vitro co-culture system amenable to high-throughput screening of thousands of patient-derived missense mutations engineered with base editing was developed to test this hypothesis. The screen and subsequent validation experiments identified genetic paralogs Plcg1 and Plcg2 as a putative immunomodulatory genes in pancreatic cancer. Now, two aims will be tested to elucidate how these mutations contribute to immune evasion across different contexts. Aim 1 will determine the mechanism of Plcg1/2- mediated immune evasion within different cell types through cellular, molecular, and biochemical experiments. Meanwhile, Aim 2 will test how tumor microenvironment and immunotherapy impact growth of Plcg1/2-mutant cancer. This research proposal is innovative because it uses precision genome editing to screen thousands of endogenously expressed, patient-derived missense mutations and identify genetic mediators of immune evasion. It is significant because it will provide mechanistic insight into how somatic variation influences tumor- immune interactions and could guide the development of new immunotherapies. The work proposed in this training plan will be conducted within the Koch Institute at MIT, a highly collaborative cancer research center with access to all of the necessary equipment, facilities, and collaborators needed to perform experimental work.

Public health relevance public domain (NIH RePORTER)

PROJECT NARRATIVE Tumors must avoid detection by the immune system in order to develop and progress. Currently, little is known about the role cancer-associated mutations play in contributing to immune evasion. This work aims to dissect the mechanism and context specificity of immune evasion and surveillance induced by missense mutations in phospholipase genes Plcg1 and Plcg2.