A SREBF2-dependent gene program drives an immunotolerant dendritic cell population during cancer progression.

Unlabelled: Dendritic cells (cDCs) are essential mediators of anti-tumor immunity. Cancers have developed mechanisms to render DCs dysfunctional within the tumor microenvironment. Utilizing CD63 as a unique surface marker, we demonstrate that mature regulatory DCs (mregDCs) suppress DC antigen cross-presentation while driving T 2 and regulatory T cell differentiation within tumor-draining lymph node tissues. Transcriptional and metabolic studies show that mregDC functionality is dependent upon the mevalonate biosynthetic pathway and the master transcription factor, SREBP2. Melanoma-derived lactate activates DC SREBP2 in the tumor microenvironment (TME) and drives mregDC development from conventional DCs. DC-specific genetic silencing and pharmacologic inhibition of SREBP2 promotes anti-tumor CD8 T cell activation and suppresses melanoma progression. CD63 mregDCs reside within the sentinel lymph nodes of melanoma patients. Collectively, this work describes a tumor-driven SREBP2-dependent program that promotes CD63 mregDC development and function while serving as a promising therapeutic target for overcoming immune tolerance in the TME.

One Sentence Summary: The metabolic transcription factor, SREBF2, regulates the development and tolerogenic function of the mregDC population within the tumor microenvironment.