A lysosome-targeted DNA nanodevice selectively targets macrophages to attenuate tumours

Activating CD8+ T cells by antigen cross-presentation is remarkably effective at eliminating tumours. Although this function is traditionally attributed to dendritic cells, tumour-associated macrophages (TAMs) can also cross-present antigens. TAMs are the most abundant tumour-infiltrating leukocyte. Yet, TAMs have not been leveraged to activate CD8+ T cells because mechanisms that modulate their ability to cross-present antigens are incompletely understood. Here we show that TAMs harbour hyperactive cysteine protease activity in their lysosomes, which impedes antigen cross-presentation, thereby preventing CD8+ T cell activation. We developed a DNA nanodevice (E64-DNA) that targets the lysosomes of TAMs in mice. E64-DNA inhibits the population of cysteine proteases that is present specifically inside the lysosomes of TAMs, improves their ability to cross-present antigens and attenuates tumour growth via CD8+ T cells. When combined with cyclophosphamide, E64-DNA showed sustained tumour regression in a triple-negative-breast-cancer model. Our studies demonstrate that DNA nanodevices can be targeted with organelle-level precision to reprogram macrophages and achieve immunomodulation in vivo.

Abstract 2766: Hypoxia-induced lactate production by tumor-associated macrophages promote tumorigenesis

Tumor-associated macrophages (TAMs) are the most prevalent immune cell in the tumor microenvironment (TME). They mainly adopt an M2-like phenotype that supports angiogenesis, attenuates anti-tumor immunity, and promotes metastasis. Blocking M2 activation of TAMs in pre-clinical models attenuates tumor growth and metastasis, and high abundance of M2-like TAMs is associated with poor patient survival across many cancer types. Despite of TAMs as a promising therapeutic target, the mechanisms producing their M2-like phenotype is poorly understood. This understanding is required to develop effective TAM-targeting therapeutics and identify patients that might benefit from them. One potential pathway to influence macrophage polarization is via metabolic reprogramming. The traditional view is that glycolysis supports a pro-inflammatory M1 phenotype in macrophages, while oxidative phosphorylation is required for their M2 phenotypes. Our recent work challenged this paradigm. We showed that treating macrophages with LPS or bacteria (conditions that support M1 activation) induces lactate production, which in turn drives a late phase switch to an M2-like phenotypes. The mechanism underlying this surprising observation involves a novel lactate-induced epigenetic modification termed histone lysine lactylation (Kla) that marks promoters of M2-like genes and directly promote transcription. In tumors, hypoxia is a key environmental stimulus that induces lactate production. The goal of this study was to examine if hypoxia-induced lactate production by TAMs metabolically reprograms them to promote Kla-M2 pathway to influence tumorigenesis. Here, we showed that hypoxia-induced lactate production by macrophages elevates the expression of M2-like genes, marked by Kla at their promotes. We further demonstrated the spatial and quantitative relationship between hypoxia, Kla, and M2-like phenotype within a single tumor (GEM model & human tumors) and across tumors with variable hypoxia (syngeneic models). Moreover, inhibiting endogenous lactate production by TAMs (via Ldha deletion) reduces tumor growth, attenuates M2-like phenotype of TAMs, and increases CD8+ T cells in tumor with high hypoxia, but not low hypoxia. Importantly, lactate level in TME is independent of tumor hypoxia or LDHA status, suggesting that this epigenetic pathway is primarily driven by endogenous lactate production by TAM rather than exogenous lactate in TME. Collectively, our studies demonstrated an important role for a “hypoxia-induced lactate-Kla-M2 pathway” in TAMs to promote tumorigenesis.

Citation Format: Chang Cui, kasturi Chakraborty, Kelly Schoenfelt, Guolin Zhou, Xu Anna Tang, Catherine Reardon, Di Zhang, Alexander Muir, Yingming Zhao, Lev Becker. Hypoxia-induced lactate production by tumor-associated macrophages promote tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2766.

Neutrophil elastase selectively kills cancer cells and attenuates tumorigenesis

Cancer cell genetic variability and similarity to host cells have stymied development of broad anti-cancer therapeutics. Our innate immune system evolved to clear genetically diverse pathogens and limit host toxicity; however, whether/how innate immunity can produce similar effects in cancer is unknown. Here, we show that human, but not murine, neutrophils release catalytically active neutrophil elastase (ELANE) to kill many cancer cell types while sparing non-cancer cells. ELANE proteolytically liberates the CD95 death domain, which interacts with histone H1 isoforms to selectively eradicate cancer cells. ELANE attenuates primary tumor growth and produces a CD8+T cell-mediated abscopal effect to attack distant metastases. Porcine pancreatic elastase (ELANE homolog) resists tumor-derived protease inhibitors and exhibits markedly improved therapeutic efficacy. Altogether, our studies suggest that ELANE kills genetically diverse cancer cells with minimal toxicity to non-cancer cells, raising the possibility of developing it as a broad anti-cancer therapy.