Identifying the impact of autocrine LIF signaling on myeloid cells.

Autocrine LIF signaling enhances tumorigenesis and inflammation.

Depletion of interstitial macrophages in Lkb1 mutant lung tumors after clodronate administration increases effector T cell function.

Autocrine LIF signaling induces Lkb1 mutant tumor plasticity.

Inhibition of autocrine LIF signaling enhances T cell effector function.

LIF neutralization eliminates a dedifferentiated stem-like tumor cell state.

Lkb1 mutant tumors transcriptionally upregulate the cytokine LIF.

Immune Analysis of Lkb1 mutant lung tumors by scRNA-seq.

Immune analysis of murine Lkb1 mutant lung tumors by flow cytometry.

LKB1 mutations in lung cancer promote an immunosuppressive tumor microenvironment, but the underlying mechanisms remain unknown. Using genetically engineered mouse models and human tumor samples, we demonstrate that LKB1 loss leads to high expression of the cytokine leukemia-inhibitory factor (LIF), which through a cancer cell-autonomous autocrine loop, orchestrates the infiltration of immunosuppressive SiglecFHi neutrophils and Arg1+ interstitial macrophages. Genetic deletion of Lifr, the receptor for LIF, on Lkb1-mutant lung tumors revealed that autocrine LIF signaling induces tumor plasticity and the emergence of a Sox17+ dedifferentiated inflammatory cell state. Antibody-mediated LIF neutralization selectively eliminates the Sox17+ tumor cell state, reduces immunosuppressive myeloid cells, and enhances antitumor T-cell responses. Our study uncovers a novel LKB1-LIF axis driving immune evasion and identifies LIF as a potential therapeutic target in LKB1-mutant lung cancer. This work highlights the interplay between tumor genetics, cellular plasticity, and immune regulation in lung cancer progression. SIGNIFICANCE:LKB1-mutant lung cancers express LIF, which induces an immunosuppressive Sox17+ tumor state. Anti-LIF therapy eliminates this state and restores antitumor immunity, revealing a novel vulnerability in this aggressive cancer subtype lacking effective targeted therapies.

Loss of function mutations in Lkb1 enhance tumorigenesis.

Loss of autocrine LIF signaling alters the immune infiltration of Lkb1 mutant tumors.

Immune analysis of human LKB1 mutant lung tumors.

Elevated or ectopic expression of neuronal receptors promotes tumour progression in many cancer types1,2; neuroendocrine (NE) transformation of adenocarcinomas has also been associated with increased aggressiveness3. Whether the defining neuronal feature, namely electrical excitability, exists in cancer cells and impacts cancer progression remains mostly unexplored. Small-cell lung cancer (SCLC) is an archetypal example of a highly aggressive NE cancer and comprises two major distinct subpopulations: NE cells and non-NE cells4,5. Here we show that NE cells, but not non-NE cells, are excitable, and their action potential firing directly promotes SCLC malignancy. However, the resultant high ATP demand leads to an unusual dependency on oxidative phosphorylation in NE cells. This finding contrasts with the properties of most cancer cells reported in the literature, which are non-excitable and rely heavily on aerobic glycolysis. Additionally, we found that non-NE cells metabolically support NE cells, a process akin to the astrocyte-neuron metabolite shuttle6. Finally, we observed drastic changes in the innervation landscape during SCLC progression, which coincided with increased intratumoural heterogeneity and elevated neuronal features in SCLC cells, suggesting an induction of a tumour-autonomous vicious cycle, driven by cancer cell-intrinsic electrical activity, which confers long-term tumorigenic capability and metastatic potential.

DNA mismatch repair deficiency (MMRd) is associated with a high tumor mutational burden (TMB) and sensitivity to immune checkpoint blockade (ICB) therapy. Nevertheless, most MMRd tumors do not durably respond to ICB and critical questions remain about immunosurveillance and TMB in these tumors. In the present study, we developed autochthonous mouse models of MMRd lung and colon cancer. Surprisingly, these models did not display increased T cell infiltration or ICB response, which we showed to be the result of substantial intratumor heterogeneity of mutations. Furthermore, we found that immunosurveillance shapes the clonal architecture but not the overall burden of neoantigens, and T cell responses against subclonal neoantigens are blunted. Finally, we showed that clonal, but not subclonal, neoantigen burden predicts ICB response in clinical trials of MMRd gastric and colorectal cancer. These results provide important context for understanding immune evasion in cancers with a high TMB and have major implications for therapies aimed at increasing TMB.

Figure S6 provides insight into gene expression analysis of other cancers where BRG1 is frequently mutated.

Figure S5 provides details about drug screens in H2009 cells, along with further in vitro and in vivo characterization of ATR inhibition responses in lung cancers with BRG1 mutations or loss.

Mutations and copy number alterations in PDX models used in this study

Supplementary Figures related to Figures 1-6

Tumor mutations can influence the surrounding microenvironment leading to suppression of anti-tumor immune responses and thereby contributing to tumor progression and failure of cancer therapies. Here we use genetically engineered lung cancer mouse models and patient samples to dissect how LKB1 mutations accelerate tumor growth by reshaping the immune microenvironment. Comprehensive immune profiling of LKB1 -mutant vs wildtype tumors revealed dramatic changes in myeloid cells, specifically enrichment of Arg1 + interstitial macrophages and SiglecF Hi neutrophils. We discovered a novel mechanism whereby autocrine LIF signaling in Lkb1 -mutant tumors drives tumorigenesis by reprogramming myeloid cells in the immune microenvironment. Inhibiting LIF signaling in Lkb1 -mutant tumors, via gene targeting or with a neutralizing antibody, resulted in a striking reduction in Arg1 + interstitial macrophages and SiglecF Hi neutrophils, expansion of antigen specific T cells, and inhibition of tumor progression. Thus, targeting LIF signaling provides a new therapeutic approach to reverse the immunosuppressive microenvironment of LKB1 -mutant tumors.