Molecular and epigenetic mechanisms by which stat5 regulates polyfunctionality in antitumor cd4+ T cells.

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Presentation Time: 11:30 AM - 12:45 PM
Poster Board Number: B525
Abstract ID: 5430

Presenting Author:
Ogacheko D Okoko , PhD Candidate at Georgia Cancer Ctr.. Augusta Univ.

Abstract:

Recent clinical advances in adoptive T cell therapy (ACT) using genetically edited T cells expressing chimeric antigen receptors (CAR-T) has ushered in a new paradigm in the field of immuno-oncology. We have reported that the ectopic expression of a constitutively active form of STAT5 (CASTAT5) in CD4+ T cells reprograms the epigenetic landscape of the T cells to endow polyfunctionality and robust antitumor immunity. Here, we aim to determine the key effector molecules released by polyfunctional CD4+ T cells to exert the potent antitumor effects. We applied CRISPR/Cas9 gene-editing to knock down genes of interest (IFNg, Csf2, Ezh2). CASTAT5 CD4+ T cells lacking IFNg showed decreased donor CD4+ T cell expansion and loss of anti-tumor activity in the mouse model studied. Using CUT&Tag to analyze histone modifications, we identified active chromatin sites signifying increased transcriptional activity of Th2-type cytokines (IL4, IL13) in CASTAT5 CD4+ T cells, suggesting a role of these cytokines which are currently under investigation. Also, we showed that human T cells can be transduced with human CASTAT5, resulting in robust cytokine production (IFNg, Csf2, IL13) compared to control T cells. Human CASTAT5 T cells showed increased pSTAT5 and BCL2 levels, a downstream target of STAT5. In conclusion, our study establishes a robust experimental platform to investigate the molecular mechanisms underlying the multifaceted antitumor effects of STAT5-driven polyfunctional CD4+ T cells.