Faculty Bibliography

UNLABELLED: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/UNASSIGNED: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.

Ferroptosis has emerged over the past decade as a compelling therapeutic avenue for cancer, prompting intense interest in strategies that selectively induce or inhibit this form of cell death. Although substantial progress has been made in identifying genes that regulate ferroptosis sensitivity and in developing small-molecule modulators, it remains unclear which molecular targets offer the greatest therapeutic potential in specific tissues and contexts. Here, we highlight fundamental differences between in vitro and in vivo ferroptosis modulation, with emphasis on the integration of different techniques, mouse models, and how the tumor microenvironment shapes two major ferroptosis surveillance pathways: glutathione peroxidase 4 and ferroptosis suppressor protein 1. We propose that integrating in vivo biological constraints and microenvironmental complexity is essential for the rational design and successful translation of ferroptosis-targeted therapies.

Lung cancer predominantly affects older individuals, yet how physiological ageing influences tumour evolution remains poorly understood¹. Here we show that ageing reprograms the evolutionary trajectory of KRAS-driven lung adenocarcinoma, limiting primary tumour growth while promoting metastatic dissemination through epigenetic activation of the integrated stress response (ISR). The ISR effector ATF4 drives epithelial and metabolic plasticity, conferring metastatic competence. Mechanistically, aged tumour cells show increased sensitivity to the PERK-eIF2α arm of the unfolded protein response, sustaining persistent ATF4 signalling. Targeting ISR-ATF4 genetically or pharmacologically abolishes these adaptations and limits dissemination, whereas ATF4 overexpression alone is sufficient to induce metastasis. The ageing-ATF4 axis imposes a dependency on glutamine metabolism, revealing a therapeutically actionable vulnerability. Clinical analyses confirm that ATF4 is enriched in aged tumours and correlates with poor survival and advanced-stage disease. Collectively, these results define epigenetic ISR-ATF4 activation as a causal driver of lineage plasticity and metastasis in aged tumours, revealing a therapeutic opportunity in older patients with lung adenocarcinoma, the most common yet understudied subset of lung cancer.

Cancer cells activate the integrated stress response (ISR) to adapt to stress and resist therapy¹. ISR signals converge on activating transcription factor 4 (ATF4), which controls cell-intrinsic transcriptional programs that are involved in metabolic adaptation, survival and growth^2,3. However, whether the ISR-ATF4 axis influences anti-tumour immune responses remains mostly unknown. Here we show that loss of ATF4 decreases tumour progression considerably in immunocompetent mice, but not in immunocompromised ones, by enhancing T cell-dependent anti-cancer immune responses. An unbiased genetic screen of ATF4-regulated genes identifies lipocalin 2 (LCN2) as the principal ATF4-dependent effector that impairs anti-tumour immunity by favouring infiltration with immunosuppressive interstitial macrophages. Furthermore, we find that LCN2 promotes T cell exclusion and immune evasion in preclinical mouse models, and correlates with decreased T cell infiltration in patients with lung and pancreatic adenocarcinomas. Anti-LCN2 antibodies promote robust anti-tumour T cell responses in mouse models of aggressive solid tumours. Our study shows that the ATF4-LCN2 axis has a cell-extrinsic role in suppressing anti-cancer immunity, and could pave the way for an immunotherapy approach that targets LCN2.

Emerging evidence indicates that cancer cells are susceptible to ferroptosis, a form of cell death that is triggered by uncontrolled lipid peroxidation^1-3. Despite broad enthusiasm about harnessing ferroptosis as a novel anti-cancer strategy, whether ferroptosis is a barrier to tumorigenesis and can be leveraged therapeutically remains unknown^4,5. Here, using genetically engineered mouse models of lung adenocarcinoma, we performed tumour-specific loss-of-function studies of two key ferroptosis suppressors, GPX4^6,7 and ferroptosis suppressor protein 1 (FSP1)^8,9, and observed increased lipid peroxidation and robust suppression of tumorigenesis, suggesting that lung tumours are highly sensitive to ferroptosis. Furthermore, across multiple pre-clinical models, we found that FSP1 was required for ferroptosis protection in vivo, but not in vitro, underscoring a heightened need to buffer lipid peroxidation under physiological conditions. Lipidomic analyses revealed that Fsp1-knockout tumours had an accumulation of lipid peroxides, and inhibition of ferroptosis with genetic, dietary or pharmacological approaches effectively restored the growth of Fsp1-knockout tumours in vivo. Unlike GPX4, expression of FSP1 (also known as AIFM2) was prognostic for disease progression and poorer survival in patients with lung adenocarcinoma, highlighting its potential as a viable therapeutic target. To this end, we demonstrated that pharmacologic inhibition of FSP1 had significant therapeutic benefit in pre-clinical lung cancer models. Our studies highlight the importance of ferroptosis suppression in vivo and pave the way for FSP1 inhibition as a therapeutic strategy for patients with lung cancer.

Retrons are a retroelement class found in diverse prokaryotes that can be adapted to augment CRISPR-Cas9 genome engineering technology to efficiently rewrite short stretches of genetic information in bacteria and yeast. However, efficiency in human cells has been limited by unknown factors. We identified non-coding RNA (ncRNA) instability and impaired Cas9 activity due to 5' sgRNA extension as key contributors to low retron editor efficiency in human cells. We re-engineered the Eco1 ncRNA to incorporate an exoribonuclease-resistant RNA pseudoknot from the Zika virus 3' UTR and devised an RNA processing strategy using Csy4 ribonuclease to minimize 5' sgRNA extension. This strategy increased steady-state ncRNA levels and rescued sgRNA activity, leading to increased templated repair. This work reveals a previously unappreciated role for ncRNA stability in retron editor efficiency in human cells and presents an enhanced Eco1 retron editor capable of precise genome editing in human cells from a single integrated lentivirus and, in the context of the nCas9 H840A nickase, without creating double-strand breaks.

Around 40% of the US population and 1 in 6 individuals worldwide have obesity, with the incidence surging globally^1,2. Various dietary interventions, including carbohydrate, fat and, more recently, amino acid restriction, have been explored to combat this epidemic^3-6. Here we investigated the impact of removing individual amino acids on the weight profiles of mice. We show that conditional cysteine restriction resulted in the most substantial weight loss when compared to essential amino acid restriction, amounting to 30% within 1 week, which was readily reversed. We found that cysteine deficiency activated the integrated stress response and oxidative stress response, which amplify each other, leading to the induction of GDF15 and FGF21, partly explaining the phenotype^7-9. Notably, we observed lower levels of tissue coenzyme A (CoA), which has been considered to be extremely stable¹⁰, resulting in reduced mitochondrial functionality and metabolic rewiring. This results in energetically inefficient anaerobic glycolysis and defective tricarboxylic acid cycle, with sustained urinary excretion of pyruvate, orotate, citrate, α-ketoglutarate, nitrogen-rich compounds and amino acids. In summary, our investigation reveals that cysteine restriction, by depleting GSH and CoA, exerts a maximal impact on weight loss, metabolism and stress signalling compared with other amino acid restrictions. These findings suggest strategies for addressing a range of metabolic diseases and the growing obesity crisis.