Targeting Lymph Node Dependent Immune Tolerance in Cancer

Abstract public domain (NIH RePORTER)

Project Summary In most solid tumors, lymph node (LN) metastasis precedes further dissemination. We have shown that tumor cells infiltrating LNs activate transcriptional programs that dramatically alter LN-resident immune cells, leading to the induction of tumor-specific regulatory T cells (Tregs) that facilitate metastasis to distant sites. Recently, we discovered that macrophages expressing the erythropoietin receptor (EPOR) infiltrate LNs before tumor cells, promoting tumor invasion and Treg expansion. Additionally, histone deacetylase (HDAC) 11 is upregulated in LN-infiltrating tumor cells, enhancing transcription of interferon-responsive genes such as MHC Class I and enabling the tumors to evade NK cell attack and promote an immunosuppressive environment. Hypothesis and Objectives: We hypothesize that both LN-infiltrating EPOR+ macrophages and HDAC11 in tumor cells contribute to LN metastasis. Our objectives are to validate this hypothesis and show that targeting these mechanisms can prevent and eliminate LN metastases. Specific Aims: We will investigate 1) the mechanisms by which macrophages facilitate LN tumor invasion and promote tumor-specific Tregs; 2) the mechanism by which HDAC11-mediated epigenetic modifications in cancer cells enable LN metastasis and promote immunosuppression; and 3) the potential to pharmacologically target these distinct pathways to prevent and treat LN metastasis. Study Design: Using multiplex microscopy, flow cytometry, single-cell RNA sequencing and ATAC sequencing, and in-house generated mouse models of pancreatic ductal adenocarcinoma, colorectal cancer and melanoma, we will evaluate the role of macrophages in LN metastatic seeding and induction of tumor-specific Tregs (Aim 1), investigate the role of tumor-intrinsic HDAC11 in immune evasion and lymphatic spread (Aim 2), and use monoclonal antibodies, siEPOR-loaded lipid nanoparticles, and specific HDAC11-targeting molecules to evaluate their impact on LN metastasis, tumor burden, and sensitization to immune checkpoint blockade (Aim 3). Justification for the use of animal models: Experiments must be performed in mice, because only in mice are we able to perform time-dependent analysis of tumor spread to lymph nodes, identify the cells and molecules responsible for lymph node metastasis, and target them to prevent and treat such metastasis. Expected Results and Impact: Upon conclusion of these studies, we expect to have identified the mechanisms by which tumors spread to LNs and shown that targeting these mechanisms can prevent and treat LN metastasis.

Public health relevance public domain (NIH RePORTER)

Project Narrative Cancer typically spreads first to nearby lymph nodes (LNs) where they alter the immune system in a way that enables the cancer to spread to other tissues. We recently discovered that white blood cells called macrophages, along with a molecule in tumor cells called HDAC11, enable cancers to spread to LNs. We will study cancers in mice to determine how these cancer-promoting mechanisms work and test new treatments to block them with the promise that our discoveries will lead to new and more effective ways to treat human cancers.