PPIA dictates NRF2 stability to promote lung cancer progression.

Nuclear factor erythroid 2-related factor 2 (NRF2) hyperactivation has been established as an oncogenic driver in a variety of human cancers, including non-small cell lung cancer (NSCLC). However, despite massive efforts, no specific therapy is currently available to target NRF2 hyperactivation. Here, we identify peptidylprolyl isomerase A (PPIA) is required for NRF2 protein stability. Ablation of PPIA promotes NRF2 protein degradation and blocks NRF2-driven growth in NSCLC cells. Mechanistically, PPIA physically binds to NRF2 and blocks the access of ubiquitin/Kelch Like ECH Associated Protein 1 (KEAP1) to NRF2, thus preventing ubiquitin-mediated degradation. Our X-ray co-crystal structure reveals that PPIA directly interacts with a NRF2 interdomain linker via a trans-proline 174-harboring hydrophobic sequence. We further demonstrate that an FDA-approved drug, cyclosporin A (CsA), impairs the interaction of NRF2 with PPIA, inducing NRF2 ubiquitination and degradation. Interestingly, CsA interrupts glutamine metabolism mediated by the NRF2/KLF5/SLC1A5 pathway, consequently suppressing the growth of NRF2-hyperactivated NSCLC cells. CsA and a glutaminase inhibitor combination therapy significantly retard tumor progression in NSCLC patient-derived xenograft (PDX) models with NRF2 hyperactivation. Our study demonstrates that targeting NRF2 protein stability is an actionable therapeutic approach to treat NRF2-hyperactivated NSCLC.

TET2-STAT3-CXCL5 nexus promotes neutrophil lipid transfer to fuel lung adeno-to-squamous transition.

Phenotypic plasticity is a rising cancer hallmark, and lung adeno-to-squamous transition (AST) triggered by LKB1 inactivation is significantly associated with drug resistance. Mechanistic insights into AST are urgently needed to identify therapeutic vulnerability in LKB1-deficient lung cancer. Here, we find that ten-eleven translocation (TET)-mediated DNA demethylation is elevated during AST in KrasLSL-G12D/+; Lkb1L/L (KL) mice, and knockout of individual Tet genes reveals that Tet2 is required for squamous transition. TET2 promotes neutrophil infiltration through STAT3-mediated CXCL5 expression. Targeting the STAT3-CXCL5 nexus effectively inhibits squamous transition through reducing neutrophil infiltration. Interestingly, tumor-infiltrating neutrophils are laden with triglycerides and can transfer the lipid to tumor cells to promote cell proliferation and squamous transition. Pharmacological inhibition of macropinocytosis dramatically inhibits neutrophil-to-cancer cell lipid transfer and blocks squamous transition. These data uncover an epigenetic mechanism orchestrating phenotypic plasticity through regulating immune microenvironment and metabolic communication, and identify therapeutic strategies to inhibit AST.

Adeno-to-squamous transition drives resistance to KRAS inhibition in LKB1 mutant lung cancer.

KRASG12C inhibitors (adagrasib and sotorasib) have shown clinical promise in targeting KRASG12C-mutated lung cancers; however, most patients eventually develop resistance. In lung patients with adenocarcinoma with KRASG12C and STK11/LKB1 co-mutations, we find an enrichment of the squamous cell carcinoma gene signature in pre-treatment biopsies correlates with a poor response to adagrasib. Studies of Lkb1-deficient KRASG12C and KrasG12D lung cancer mouse models and organoids treated with KRAS inhibitors reveal tumors invoke a lineage plasticity program, adeno-to-squamous transition (AST), that enables resistance to KRAS inhibition. Transcriptomic and epigenomic analyses reveal ΔNp63 drives AST and modulates response to KRAS inhibition. We identify an intermediate high-plastic cell state marked by expression of an AST plasticity signature and Krt6a. Notably, expression of the AST plasticity signature and KRT6A at baseline correlates with poor adagrasib responses. These data indicate the role of AST in KRAS inhibitor resistance and provide predictive biomarkers for KRAS-targeted therapies in lung cancer.

EML4-ALK fusions drive lung adeno-to-squamous transition through JAK-STAT activation.

Human lung adenosquamous cell carcinoma (LUAS), containing both adenomatous and squamous pathologies, exhibits strong cancer plasticity. We find that ALK rearrangement is detectable in 5.1-7.5% of human LUAS, and transgenic expression of EML4-ALK drives lung adenocarcinoma (LUAD) formation initially and squamous transition at late stage. We identify club cells as the main cell-of-origin for squamous transition. Through recapitulating lineage transition in organoid system, we identify JAK-STAT signaling, activated by EML4-ALK phase separation, significantly promotes squamous transition. Integrative study with scRNA-seq and immunostaining identify a plastic cell subpopulation in ALK-rearranged human LUAD showing squamous biomarker expression. Moreover, those relapsed ALK-rearranged LUAD show notable upregulation of squamous biomarkers. Consistently, mouse squamous tumors or LUAD with squamous signature display certain resistance to ALK inhibitor, which can be overcome by combined JAK1/2 inhibitor treatment. This study uncovers strong plasticity of ALK-rearranged tumors in orchestrating phenotypic transition and drug resistance and proposes a potentially effective therapeutic strategy.

Proteogenomic characterization of small cell lung cancer identifies biological insights and subtype-specific therapeutic strategies.

We performed comprehensive proteogenomic characterization of small cell lung cancer (SCLC) using paired tumors and adjacent lung tissues from 112 treatment-naive patients who underwent surgical resection. Integrated multi-omics analysis illustrated cancer biology downstream of genetic aberrations and highlighted oncogenic roles of FAT1 mutation, RB1 deletion, and chromosome 5q loss. Two prognostic biomarkers, HMGB3 and CASP10, were identified. Overexpression of HMGB3 promoted SCLC cell migration via transcriptional regulation of cell junction-related genes. Immune landscape characterization revealed an association between ZFHX3 mutation and high immune infiltration and underscored a potential immunosuppressive role of elevated DNA damage response activity via inhibition of the cGAS-STING pathway. Multi-omics clustering identified four subtypes with subtype-specific therapeutic vulnerabilities. Cell line and patient-derived xenograft-based drug tests validated the specific therapeutic responses predicted by multi-omics subtyping. This study provides a valuable resource as well as insights to better understand SCLC biology and improve clinical practice.

Cryoablation triggers type I interferon-dependent antitumor immunity and potentiates immunotherapy efficacy in lung cancer.

BACKGROUND: Cryoablation is a minimally invasive option for patients with medically inoperable non-small cell lung cancer (NSCLC) and can trigger abscopal immune-regulatory effects. However, it remains unclear how cryoablation affects the host-level immune response in NSCLC. In this study, we investigated the local and systemic immunological effects of cryoablation and the potential of combining cryoablation with programmed cell death protein 1 (PD-1) blockade to boost immunotherapy efficacy in NSCLC. METHODS: We first investigated systemic immunological effects induced by cryoablation in patients with early-stage NSCLC. Subsequently, we explored cryoablation-induced antitumor immunity and the underlying biological mechanisms using KP (Kras G12D/+, Tp53 -/-) mutant lung cancer cell allograft mouse models. Moreover, the synergistic efficacy of cryoablation and PD-1 blockade was explored in both mouse models and patients with unresectable NSCLC. RESULTS: We found that cryoablation significantly increased circulating CD8+ T cell subpopulations and proinflammatory cytokines in patients with early-stage NSCLC. In lung cancer cell allograft mouse models, we demonstrated that cryoablation resulted in abscopal growth inhibition of contralateral, non-ablated tumors. Integrated analysis of bulk, single-cell RNA and T cell receptor (TCR) sequencing data revealed that cryoablation reprogrammed the intratumoral immune microenvironment and increased CD8+ T cell infiltration with higher effector signature, interferon (IFN) response, and cytolytic activity. Mechanistically, cryoablation promoted antitumor effect through the STING-dependent type I IFN signaling pathway, and type I IFN signaling blockade attenuated this antitumor effect. We also found that the combination of PD-1 blockade with cryoablation further inhibited tumor growth compared with either treatment alone in an allograft mouse model. Moreover, the combination therapy induced notable tumor suppression and CD8+ T cell infiltration in patients with unresectable NSCLC. CONCLUSIONS: Our results provide mechanistic insights into how cryoablation triggers the antitumor immune effect in lung cancer, thereby potentiating programmed cell death ligand 1 (PD-L1)/PD-1 blockade efficacy in the clinical treatment of NSCLC.

Med23 deficiency reprograms the tumor microenvironment to promote lung tumorigenesis.

BACKGROUND: Lung cancer is the leading cause of cancer-related death worldwide. We previously found that Mediator complex subunit 23 (MED23) is important for the tumourigenicity of lung cancer cells with hyperactive Ras activity in vitro, although the in vivo function of MED23 in lung tumourigenesis remains to be explored. METHODS: In this study, we utilized well-characterized KrasG12D-driven non-small cell lung cancer mouse model to investigate the role of MED23 in lung cancer. The lung tumour progression was evaluated by H&E and IHC analysis. Western blotting and qRT-PCR assays were performed to detect changes in gene expression. Immune cells were analyzed by FACS technology. RNA-seq and reporter assays were conducted to explore the mechanism. RESULTS: We observed that lung epithelial Med23 deletion by adeno-Cre resulted in a significant increase in KrasG12D tumour number and size, which was further verified with another mouse model with Med23 specifically deleted in alveolar type II cells. Mice with lung-specific Med23 deficiency also exhibited accelerated tumourigenesis, and a higher proliferation rate for tumour cells, along with increased ERK phosphorylation. Notably, the numbers of infiltrating CD4+ T cells and CD8+ T cells were significantly reduced in the lungs of Med23-deficient mice, while the numbers of myeloid-derived suppressor cells (MDSCs) and Treg cells were significantly increased, suggesting the enhanced immune escape capability of the Med23-deficient lung tumours. Transcriptomic analysis revealed that the downregulated genes in Med23-deficient lung tumour tissues were associated with the immune response. Specifically, Med23 deficiency may compromise the MHC-I complex formation, partially through down-regulating B2m expression. CONCLUSIONS: Collectively, these findings revealed that MED23 may negatively regulate Kras-induced lung tumourigenesis in vivo, which would improve the precise classification of KRAS-mutant lung cancer patients and provide new insights for clinical interventions.

Correction to: Identification of TAZ as the essential molecular switch in orchestrating SCLC phenotypic transition and metastasis.

[This corrects the article DOI: 10.1093/nsr/nwab232.].

Prognosis value of microscopic bile duct invasion in hepatocellular carcinoma: A multicenter study.

OBJECTIVE: To evaluate the prognostic significance of microscopic bile duct invasion (MiBDI) in hepatocellular carcinoma (HCC) following R0 resection. PATIENTS AND METHODS: Patients who underwent R0 resection for HCC at nine medical centers were stratified into five groups: neither bile duct nor vascular invasion (MiBDI-MVI-), microscopic bile duct invasion alone (MiBDI+MVI-), both microscopic bile duct and vascular invasion (MiBDI+MVI+), microscopic vascular invasion alone (MiBDI-MVI+), and macroscopic bile duct invasion (MaBDI). Overall survival (OS) was assessed using Kaplan-Meier analysis, and independent risk factors of OS were determined using Cox proportional hazards models. RESULTS: A total of 377 HCC cases were analyzed. The OS for MiBDI+MVI- was similar to that of MiBDI-MVI- (p > 0.05) but better than MiBDI+MVI+, MiBDI-MVI+, and MaBDI (all p < 0.05). Multivariate analysis indicated that MiBDI was not an independent risk factor for OS, while MVI and MaBDI were. CONCLUSIONS: Overall survival (OS) in patients with MiBDI was superior to those with MVI and MaBDI. Isolated MiBDI did not influence OS in patients with HCC after R0 resection.

Selective activator of human ClpP triggers cell cycle arrest to inhibit lung squamous cell carcinoma.

Chemo-activation of mitochondrial ClpP exhibits promising anticancer properties. However, we are currently unaware of any studies using selective and potent ClpP activators in lung squamous cell carcinoma. In this work, we report on such an activator, ZK53, which exhibits therapeutic effects on lung squamous cell carcinoma in vivo. The crystal structure of ZK53/ClpP complex reveals a π-π stacking effect that is essential for ligand binding selectively to the mitochondrial ClpP. ZK53 features on a simple scaffold, which is distinct from the activators with rigid scaffolds, such as acyldepsipeptides and imipridones. ZK53 treatment causes a decrease of the electron transport chain in a ClpP-dependent manner, which results in declined oxidative phosphorylation and ATP production in lung tumor cells. Mechanistically, ZK53 inhibits the adenoviral early region 2 binding factor targets and activates the ataxia-telangiectasia mutated-mediated DNA damage response, eventually triggering cell cycle arrest. Lastly, ZK53 exhibits therapeutic effects on lung squamous cell carcinoma cells in xenograft and autochthonous mouse models.

CBX4 deletion promotes tumorigenesis under KrasG12D background by inducing genomic instability.

Chromobox protein homolog 4 (CBX4) is a component of the Polycomb group (PcG) multiprotein Polycomb repressive complexes 1 (PRC1), which is participated in several processes including growth, senescence, immunity, and tissue repair. CBX4 has been shown to have diverse, even opposite functions in different types of tissue and malignancy in previous studies. In this study, we found that CBX4 deletion promoted lung adenocarcinoma (LUAD) proliferation and progression in KrasG12D mutated background. In vitro, over 50% Cbx4L/L, KrasG12D mouse embryonic fibroblasts (MEFs) underwent apoptosis in the initial period after Adeno-Cre virus treatment, while a small portion of survival cells got increased proliferation and transformation abilities, which we called selected Cbx4-/-, KrasG12D cells. Karyotype analysis and RNA-seq data revealed chromosome instability and genome changes in selected Cbx4-/-, KrasG12D cells compared with KrasG12D cells. Further study showed that P15, P16 and other apoptosis-related genes were upregulated in the primary Cbx4-/-, KrasG12D cells due to chromosome instability, which led to the large population of cell apoptosis. In addition, multiple pathways including Hippo pathway and basal cell cancer-related signatures were altered in selected Cbx4-/-, KrasG12D cells, ultimately leading to cancer. We also found that low expression of CBX4 in LUAD was associated with poorer prognosis under Kras mutation background from the human clinical data. To sum up, CBX4 deletion causes genomic instability to induce tumorigenesis under KrasG12D background. Our study demonstrates that CBX4 plays an emerging role in tumorigenesis, which is of great importance in guiding the clinical treatment of lung adenocarcinoma.

The intratumor mycobiome promotes lung cancer progression via myeloid-derived suppressor cells.

Although polymorphic microbiomes have emerged as hallmarks of cancer, far less is known about the role of the intratumor mycobiome as living microorganisms in cancer progression. Here, using fungi-enriched DNA extraction and deep shotgun metagenomic sequencing, we have identified enriched tumor-resident Aspergillus sydowii in patients with lung adenocarcinoma (LUAD). By three different syngeneic lung cancer mice models, we find that A. sydowii promotes lung tumor progression via IL-1ß-mediated expansion and activation of MDSCs, resulting in suppressed activity of cytotoxic T lymphocyte cells and accumulation of PD-1+ CD8+ T cells. This is mediated by IL-1ß secretion via ß-glucan/Dectin-1/CARD9 pathway. Analysis of human samples confirms that enriched A. sydowii is associated with immunosuppression and poor patient outcome. Our findings suggest that intratumor mycobiome, albeit at low biomass, promotes lung cancer progression and could be targeted at the strain level to improve patients with LUAD outcome.

Identification of XAF1 as an endogenous AKT inhibitor.

AKT kinase is a key regulator in cell metabolism and survival, and its activation is strictly modulated. Herein, we identify XAF1 (XIAP-associated factor) as a direct interacting protein of AKT1, which strongly binds the N-terminal region of AKT1 to block its K63-linked poly-ubiquitination and subsequent activation. Consistently, Xaf1 knockout causes AKT activation in mouse muscle and fat tissues and reduces body weight gain and insulin resistance induced by high-fat diet. Pathologically, XAF1 expression is low and anti-correlated with the phosphorylated p-T308-AKT signal in prostate cancer samples, and Xaf1 knockout stimulates the p-T308-AKT signal to accelerate spontaneous prostate tumorigenesis in mice with Pten heterozygous loss. And ectopic expression of wild-type XAF1, but not the cancer-derived P277L mutant, inhibits orthotopic tumorigenesis. We further identify Forkhead box O 1 (FOXO1) as a transcriptional regulator of XAF1, thus forming a negative feedback loop between AKT1 and XAF1. These results reveal an important intrinsic regulatory mechanism of AKT signaling.

Understanding SCLC heterogeneity and plasticity in cancer metastasis and chemotherapy resistance.

Small cell lung cancer (SCLC) accounts for approximately 15% of all lung cancer cases and features a strong predilection for early metastasis and extremely poor prognosis. Despite being highly sensitive to chemotherapy and/or radiotherapy initially, most SCLC patients develop therapeutic resistance within one year and die of distant metastases. Multiple studies have revealed the high heterogeneity and strong plasticity of SCLC associated with frequent metastases and early development of therapeutic resistance as well as poor clinical outcome. Importantly, different SCLC subtypes are associated with different therapeutic vulnerabilities, and the inflamed subtype tends to have the best response to immunotherapy, which highlights the importance of precision medicine in the clinic. Here, we review recent advances in SCLC heterogeneity and plasticity and their link to distant metastases and chemotherapy resistance. We hope that a better understanding of the molecular mechanisms underlying SCLC malignant progression will help to develop better intervention strategies for this deadly disease.

In vivo metabolomics identifies CD38 as an emergent vulnerability in LKB1 -mutant lung cancer.

LKB1/STK11 is a serine/threonine kinase that plays a major role in controlling cell metabolism, resulting in potential therapeutic vulnerabilities in LKB1-mutant cancers. Here, we identify the NAD + degrading ectoenzyme, CD38, as a new target in LKB1-mutant NSCLC. Metabolic profiling of genetically engineered mouse models (GEMMs) revealed that LKB1 mutant lung cancers have a striking increase in ADP-ribose, a breakdown product of the critical redox co-factor, NAD + . Surprisingly, compared with other genetic subsets, murine and human LKB1-mutant NSCLC show marked overexpression of the NAD+-catabolizing ectoenzyme, CD38 on the surface of tumor cells. Loss of LKB1 or inactivation of Salt-Inducible Kinases (SIKs)-key downstream effectors of LKB1- induces CD38 transcription induction via a CREB binding site in the CD38 promoter. Treatment with the FDA-approved anti-CD38 antibody, daratumumab, inhibited growth of LKB1-mutant NSCLC xenografts. Together, these results reveal CD38 as a promising therapeutic target in patients with LKB1 mutant lung cancer. SIGNIFICANCE: Loss-of-function mutations in the LKB1 tumor suppressor of lung adenocarcinoma patients and are associated with resistance to current treatments. Our study identified CD38 as a potential therapeutic target that is highly overexpressed in this specific subtype of cancer, associated with a shift in NAD homeostasis.

Counteracting lineage-specific transcription factor network finely tunes lung adeno-to-squamous transdifferentiation through remodeling tumor immune microenvironment.

Human lung adenosquamous cell carcinoma (LUAS), containing both adenomatous and squamous pathologies, harbors strong plasticity and is significantly associated with poor prognosis. We established an up-to-date comprehensive genomic and transcriptomic landscape of LUAS in 109 Chinese specimens and demonstrated LUAS development via adeno-to-squamous transdifferentiation. Unsupervised transcriptomic clustering and dynamic network biomarker analysis identified an inflammatory subtype as the critical transition stage during LUAS development. Dynamic dysregulation of the counteracting lineage-specific transcription factors (TFs), containing adenomatous TFs NKX2-1 and FOXA2, and squamous TFs TP63 and SOX2, finely tuned the lineage transition via promoting CXCL3/5-mediated neutrophil infiltration. Genomic clustering identified the most malignant subtype featured with STK11-inactivation, and targeting LSD1 through genetic deletion or pharmacological inhibition almost eradicated STK11-deficient lung tumors. These data collectively uncover the comprehensive molecular landscape, oncogenic driver spectrum and therapeutic vulnerability of Chinese LUAS.