A role for LKB1 gene in human cancer beyond the Peutz-Jeghers syndrome

Liver kinase B1 expression is associated with improved prognosis and tumor immune microenvironment features in small cell lung cancer

Background

Small cell lung cancer (SCLC) is characterized by early metastatic potential and poor prognosis. Liver kinase B1 (LKB1) is a tumor suppressor and a cell metabolism regulator. LKB1 downregulation has been associated with a cold tumor immune microenvironment (TIME). We aimed to analyze the role of LKB1 in SCLC in relation to its association with overall survival (OS) and TIME components.

Methods

We retrospectively evaluated SCLC patients consecutively treated at our institution from 1996 to 2020 with available tissue. LKB1, PD-L1 on tumor cells and on tumor immune-infiltrating cells, CD8, and FOXP3 were evaluated by immunohistochemistry (IHC), categorized according to predefined cutoffs. The primary endpoint was the description of LKB1 expression, and the secondary endpoints were the association with prognosis and TIME features.

Results

Tissue samples of 138 out of 481 SCLCs were adequate for molecular analyses. Eighty patients had limited stage (LS) at diagnosis and 58 had extended stage (ES). The median LKB1 IHC score was 4. Patients with IHC score >4 (n = 67) were classified as LKB1-positive. The probability of LKB1 positivity was higher in LS [odds ratio 2.78, 95% confidence interval (95% CI) 1.18-7.14]. At the data cutoff (2 January 2024), 123 patients died. The median OS (mOS) was 14.0 months (95% CI 11.5-19.4). mOS was significantly longer in patients with LKB1-positive expression [32.4 months (95% CI 13.6-62.4) vs. 11.2 months (95% CI 8.7-14.7); p < 0.001]. At multivariate analysis, positive LKB1 expression, LS, and no weight loss at diagnosis were confirmed as independent positive prognostic factors. TIME features were evaluated in 70 patients. Unexpectedly, LKB1-negative samples were more likely to show CD8+ tumor-infiltrating lymphocytes (TILs; p = 0.013). No association with PD-L1 expression nor the presence of FOXP3+ TILs was found.

Conclusion

LKB1 expression is a potential positive prognostic marker in SCLC. In this series, LKB1 expression was negatively associated with the presence of CD8+ TILs.

STK11 genetic alterations in metastatic EGFR mutant lung cancer

This study was conducted to investigate the relationship between STK11 genetic alterations and the outcomes of patients with metastatic EGFR mutant lung cancer. Clinical characteristics and genomic data were downloaded from the cBioPortal database. The information of the case with STK11 mutation was collected from Jiangyin People's Hospital. Univariate and multivariate analyses were performed to distinguish the prognostic differences. Outcomes were analyzed before and after propensity score matching (PSM). A patient with STK11 mutation was insensitive to osimertinib and had an extremely poor prognosis. Further analysis showed that STK11 mutations had a strong mutual exclusion with EGFR mutations. A total of 960 patients with metastatic EGFR mutant lung adenocarcinoma were enrolled in the prognostic analysis. STK11 alternation was a significant predictor of worse outcomes in univariate or multivariate analyses. After PSM, patients with STK11 alternations still exhibited poor prognoses. Cell culture experiments also showed that the loss of STK11 could contribute to the resistance of osimertinib. Functionally, STK11 mutation was positively associated with metabolic signaling pathways and immune infiltrates negatively. Through drug screening, trametinib was identified to sensitize osimertinib in the STK11-deficient cell. This study found that STK11 genetic alterations portend a worse prognosis for patients with metastatic EGFR mutant lung cancer and led to osimertinib resistance potentially. MEK inhibitors could sensitize osimertinib in the STK11-deficient cell.

Lobular endocervical glandular hyperplasia diagnosed during surveillance for Peutz-Jeghers Syndrome: A case report

Background

Lobular endocervical glandular hyperplasia (LEGH) is a benign cervical condition that has been proposed as a precursor lesion to minimal deviation adenocarcinoma (MDA), a rare but highly aggressive subtype of well-differentiated gastric-type endocervical adenocarcinoma (GAS). MDA is more frequently observed in patients with Peutz-Jeghers syndrome (PJS) and is strongly associated with mutations in the STK11 gene. While LEGH is not inherently linked to PJS, its potential progression to MDA warrants vigilance, particularly in patients with PJS due to their heightened risk of gynecologic malignancies. Here, we report a case of LEGH diagnosed during surveillance for PJS, analyzed via whole genome sequencing. LEGH is a benign cervical condition, considered a precursor lesion to minimal deviation adenocarcinoma, often observed in patients with Peutz-Jeghers syndrome (PJS) and potentially linked to mutations in the STK11 gene.

Case

A 23-year-old woman, diagnosed with PJS at age 11, was referred to a gynecologist after a cystic lesion was detected in the cervix during a follow-up computed tomography scan. Initial examinations, including imaging and colposcopy, did not indicate LEGH or a malignant tumor. Imaging alone is insufficient to exclude premalignant or malignant conditions, as abnormal cervical lesions often require biopsy for a definitive diagnosis. However, cervical cytology showed nuclear atypia was minimal, but some clusters exhibited disordered alignment, and the cytoplasm contained yellowish mucus suggestive of LEGH. Based on these findings, cytology follow-up was planned. However, the patient did not return for further follow-up. After one year and five months, the patient presented with increased mucous vaginal discharge. Cervical cytology indicated atypical glandular cells, and magnetic resonance imaging with contrast enhancement revealed an enlarged cervical lesion, suggesting minimal deviation adenocarcinoma. We performed cervical conization, and a histopathological examination helped confirm LEGH. High-throughput next-generation sequencing of the excised cervical tissue revealed a missense mutation in the serine/threonine kinase 11 (STK11) gene on chromosome 19 (c.1062C > G) and three missense mutations in STK11 interacting protein (STK11IP) on chromosome 2 (c.2G > T, c.1687G > A, c.2255C > T). Mutations in STK11, particularly those affecting its regulatory domains, may significantly increase cancer risk in patients with PJS, and that STK11IP plays a crucial role in modulating STK11 activity. The patient, seeking to preserve fertility, has been monitored for five years post-surgery without evidence of malignant transformation. Continuous monitoring with periodic imaging and cytological assessments has shown no evidence of malignant transformation. The absence of elevated tumor markers further supports the conservative approach. While there are no tumor markers specific to cervical cancer, carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), and carbohydrate antigen 19-9 (CA19-9) were measured as part of the screening process in this case.

Conclusion

We conclude that whole genome sequencing in patients with PJS and LEGH could be pivotal in predicting cervical malignancy. This case emphasizes the utility of whole genome sequencing in predicting the risk of cervical malignancy in patients with PJS and LEGH and highlighting the critical role of genetic factors in the management and surveillance of these patients. Continuous monitoring post-surgery showed no evidence of malignant transformation, supporting a conservative approach in fertility-preserving treatment scenarios.

AMPK: An energy sensor for non-small cell lung cancer progression and treatment

Lung cancer (LC) is the leading cause of cancer-related morbidity and mortality in China, with non-small cell lung cancer (NSCLC) accounting for 85 % of the overall lung cancer cases. AMP-activated protein kinase (AMPK) is a key regulator of energy balance and homeostasis, and its dysregulation is a common feature in various malignancies, particularly in NSCLC with mutations in Liver kinase B1 (LKB1). Studies have shown that the AMPK signalling pathway has a dual role in NSCLC progression, both inhibiting and promoting the progression of malignant tumours. Therefore, drugs targeting the AMPK signalling pathway may hold significant promise for therapeutic application in NSCLC. This review aims to examine the manifestations and mechanisms by which AMPK and its associated signalling molecules influence NSCLC progression and treatment. Firstly, we discuss the critical importance of AMPK within the mutational context of NSCLC. Secondly, we summarise the drugs and related substances that modulate the AMPK signalling pathway in NSCLC and evaluate the evidence from preclinical studies on combination AMPK-targeted therapies to address the issue of drug resistance in NSCLC under current clinical treatments. In summary, this paper highlights the critical importance of developing AMPK-targeted drugs to enhance therapeutic efficacy in NSCLC, as well as the potential for applying these drugs in clinical therapy to overcome drug resistance.

A meta-analysis of epigenome-wide association studies of ultra-processed food consumption with DNA methylation in European children

BACKGROUND/OBJECTIVE

There is limited knowledge on how diet affects the epigenome of children. Ultra-processed food (UPF) consumption is emerging as an important factor impacting health, but mechanisms need to be uncovered. We therefore aimed to assess the association between UPF consumption and DNA methylation in children.

METHODS

We conducted a meta-analysis of epigenome-wide association studies (EWAS) from a total of 3152 children aged 5-11 years from four European studies (HELIX, Generation XXI, ALSPAC, and Generation R). UPF consumption was defined applying the Nova food classification system (group 4), and DNA methylation was measured in blood with Illumina Infinium Methylation arrays. Associations were estimated within each cohort using robust linear regression models, adjusting for relevant covariates, followed by a meta-analysis of the resulting EWAS estimates.

RESULTS

Although no CpG was significant at FDR level, we found suggestive associations (p-value < 10-5) between UPF consumption and methylation at seven CpG sites. Three of them, cg00339913 (PHYHIP), cg03041696 (intergenic), and cg03999434 (intergenic), were negatively associated, whereas the other four, cg14665028 (NHEJ1), cg18968409 (intergenic), cg24730307 (intergenic), and cg09709951 (ATF7), were positively associated with UPF intake. These CpGs have been previously associated with health outcomes such as carcinomas, and the related genes are mainly involved in pathways related to thyroid hormones and liver function.

CONCLUSION

We only found suggestive changes in methylation at 7 CpGs associated with UPF intake in a large EWAS among children: although this shows a potential impact of UPF intake on DNAm, this might not be a key mechanism underlying the health effects of UPFs in children. There is a need for more detailed dietary assessment in children studies and of intervention studies to assess potential epigenetic changes linked to a reduction in UPF in the diet.

Evaluating Safety and Clinical Activity of Front-line Treatment with Cadonilimab plus Chemotherapy in Advanced/Metastatic Nonsmall Cell Lung Cancer Harboring STK11 Genetic Aberration: A Protocol of Phase II Study

BACKGROUND

Cadonilimab is a first-in-class bispecific PD-1/CTLA-4 antibody. Serine/threonine kinase (STK11) mutation was shown to be related to low PD-L1 expression and objective response rate (ORR) in nonsmall cell lung cancer (NSCLC), resulting in poor progression-free survival (PFS) and overall survival (OS). Herein, we hypothesized that combining cadonilimab with chemotherapy could enhance antitumor immunity and extend survival in these patients. Consequently, we designed this study to explore the clinical activity and safety of cadonilimab combined with chemotherapy in patients with advanced/metastatic NSCLC harboring STK11 alteration.

TRIAL DESIGN

This single-center, open-label, single-arm phase II trial is conducted at the first affiliated hospital of Guangzhou Medical University. Treatment-naïve advanced/metastatic NSCLC patients harboring STK11 mutation will be enrolled in this study. Eligible patients will receive either cadonilimab (10mg/kg on Day 1) plus pemetrexed (500 mg/m2) and carboplatin (AUC = 5) for nonsquamous NSCLC or abraxane (100 mg/m2) and carboplatin (AUC = 5) for squamous NSCLC for 4 cycles, followed by maintenance therapy (cadonilimab plus pemetrexed or abraxane). The treatment will be discontinued when disease progression, intolerability to cadonilimab, and/or chemotherapy occurs. Measurable lesions were assessed according to the Response Evaluation Criteria in Solid Tumors (1.1). The main endpoint is ORR and safety. Subordinate endpoints include PFS, disease control rate, and duration of response.

RESULTS

The study commenced enrolment in September 2023, with preliminary findings regarding the primary endpoint anticipated by January 2025.

Integrated proteomic and glycoproteomic analysis reveals heterogeneity and molecular signatures of brain metastases from lung adenocarcinomas

Brain metastasis is a major cause of poor prognosis and death in lung adenocarcinoma (LUAD); however, the understanding of therapeutic strategies and mechanisms for brain metastases from LUAD (BM-LUAD) remains notably limited, especially at the proteomics levels. To address this issue, we conducted integrated proteomic and glycoproteomic analyses on 49 BM-LUAD tumors, revealing two distinct subtypes of the disease: BM-S1 and BM-S2. Whole exome sequencing analysis revealed that somatic mutations in STK11 and KEAP1, as well as copy number deletions on chr19p13.3, such as STK11, UQCR11, and SLC25A23, were more frequently detected in BM-S2. In BM-S1 tumors, we observed significant infiltration of GFAP + astrocytes, as evidenced by elevated levels of GFAP, GABRA2, GABRG1 and GAP43 proteins and an enrichment of astrocytic signatures in both our proteomic data and external spatial transcriptomic data. Conversely, BM-S2 tumors demonstrated higher levels of PD-1 immune cell infiltration, supported by the upregulation of PD-1 and LAG-3 genes. These findings suggest distinct microenvironmental adaptations required by the different BM-LUAD subtypes. Additionally, we observed unique glycosylation patterns between the subtypes, with increased fucosylation in BM-S1 and enhanced sialylation in BM-S2, primarily affected by glycosylation enzymes such as FUT9, B4GALT1, and ST6GAL1. Specifically, in BM-S2, these sialylation modifications are predominantly localized to the lysosomes, underscoring the critical role of N-glycosylation in the tumor progression of BM-LUAD. Overall, our study not only provides a comprehensive multi-omic data resource but also offers valuable biological insights into BM-LUAD, highlighting potential mechanisms and therapeutic targets for further investigation.

Impact of protein and small molecule interactions on kinase conformations

Protein kinases act as central molecular switches in the control of cellular functions. Alterations in the regulation and function of protein kinases may provoke diseases including cancer. In this study we investigate the conformational states of such disease-associated kinases using the high sensitivity of the kinase conformation (KinCon) reporter system. We first track BRAF kinase activity conformational changes upon melanoma drug binding. Second, we also use the KinCon reporter technology to examine the impact of regulatory protein interactions on LKB1 kinase tumor suppressor functions. Third, we explore the conformational dynamics of RIP kinases in response to TNF pathway activation and small molecule interactions. Finally, we show that CDK4/6 interactions with regulatory proteins alter conformations which remain unaffected in the presence of clinically applied inhibitors. Apart from its predictive value, the KinCon technology helps to identify cellular factors that impact drug efficacies. The understanding of the structural dynamics of full-length protein kinases when interacting with small molecule inhibitors or regulatory proteins is crucial for designing more effective therapeutic strategies.

Effect of the STK11 mutation on therapeutic efficacy and prognosis in patients with non-small cell lung cancer: a comprehensive study based on meta-analyses and bioinformatics analyses

BACKGROUND

This study aimed to systematically analyze the effect of a serine/threonine kinase (STK11) mutation (STK11mut) on therapeutic efficacy and prognosis in patients with non-small cell lung cancer (NSCLC).

METHODS

Candidate articles were identified through a search of relevant literature published on or before April 1, 2023, in PubMed, Embase, Cochrane Library, CNKI and Wanfang databases. The extracted and analyzed data included the hazard ratios (HRs) of PFS and OS, the objective response rate (ORR) of immune checkpoint inhibitors (ICIs), and the positive rates of PD-L1 expression. The HR of PFS and OS and the merged ratios were calculated using a meta-analysis. The correlation between STK11mut and clinical characteristics was further analyzed in NSCLC datasets from public databases.

RESULTS

Fourteen retrospective studies including 4317 patients with NSCLC of whom 605 had STK11mut were included. The meta-analysis revealed that the ORR of ICIs in patients with STK11mut was 10.1% (95%CI 0.9-25.2), and the positive rate of PD-L1 expression was 41.1% (95%CI 25.3-57.0). STK11mut was associated with poor PFS (HR = 1.49, 95%CI 1.28-1.74) and poor OS (HR = 1.44, 95%CI 1.24-1.67). In the bioinformatics analysis, PFS and OS in patients with STK11 alterations were worse than those in patients without alterations (p < 0.001, p = 0.002). Nutlin-3a, 5-fluorouracil, and vinorelbine may have better sensitivity in patients with STK11mut than in those with STK11wt.

CONCLUSIONS

Patients with STK11-mutant NSCLC had low PD-L1 expression and ORR to ICIs, and their PFS and OS were worse than patients with STK11wt after comprehensive treatment. In the future, more reasonable systematic treatments should be explored for this subgroup of patients with STK11-mutant NSCLC.

Development of a Genetically Engineered Mouse Model Recapitulating LKB1 and PTEN Deficiency in Gastric Cancer Pathogenesis

The LKB1 and PTEN genes are critical in gastric cancer (G.C.) development. LKB1, a robust tumor suppressor gene, encodes a serine/threonine kinase that directly triggers the activation of AMPK-an integral cellular metabolic kinase. The role of the LKB1 pathway extends to maintaining the stability of epithelial junctions by regulating E-cadherin expression. Conversely, PTEN, a frequently mutated tumor suppressor gene in various human cancers, emerges as a pivotal negative regulator of the phosphoinositide 3-kinase (PI3K) signaling pathway. This study is set to leverage the H+/K+ ATPase Cre transgene strain to precisely target Cre recombinase expression at parietal cells within the stomach. This strategic maneuver seeks to selectively nullify the functions of both LKB1 and PTEN in a manner specific to the stomach, thereby instigating the development of G.C. in a fashion akin to human gastric adenocarcinoma. Moreover, this study endeavors to dissect the intricate ways in which these alterations contribute to the histopathologic advancement of gastric tumors, their potential for invasiveness and metastasis, their angiogenesis, and the evolving tumor stromal microenvironment. Our results show that conditional deletion of PTEN and LKB1 provides an ideal cancer microenvironment for G.C. tumorigenesis by promoting cancer cell proliferation, angiogenesis, and metastasis.

Identification of a novel mitochondria-localized LKB1 variant required for the regulation of the oxidative stress response

The tumor suppressor Liver Kinase B1 (LKB1) is a multifunctional serine/threonine protein kinase that regulates cell metabolism, polarity, and growth and is associated with Peutz-Jeghers Syndrome and cancer predisposition. The LKB1 gene comprises 10 exons and 9 introns. Three spliced LKB1 variants have been documented, and they reside mainly in the cytoplasm, although two possess a nuclear-localization sequence (NLS) and are able to shuttle into the nucleus. Here, we report the identification of a fourth and novel LKB1 isoform that is, interestingly, targeted to the mitochondria. We show that this mitochondria-localized LKB1 (mLKB1) is generated from alternative splicing in the 5' region of the transcript and translated from an alternative initiation codon encoded by a previously unknown exon 1b (131 bp) hidden within the long intron 1 of LKB1 gene. We found by replacing the N-terminal NLS of the canonical LKB1 isoform, the N-terminus of the alternatively spliced mLKB1 variant encodes a mitochondrial transit peptide that allows it to localize to the mitochondria. We further demonstrate that mLKB1 colocalizes histologically with mitochondria-resident ATP Synthase and NAD-dependent deacetylase sirtuin-3, mitochondrial (SIRT3) and that its expression is rapidly and transiently upregulated by oxidative stress. We conclude that this novel LKB1 isoform, mLKB1, plays a critical role in regulating mitochondrial metabolic activity and oxidative stress response.

Opportunities and Challenges of Kava in Lung Cancer Prevention

Lung cancer is the leading cause of cancer-related deaths due to its high incidence, late diagnosis, and limited success in clinical treatment. Prevention therefore is critical to help improve lung cancer management. Although tobacco control and tobacco cessation are effective strategies for lung cancer prevention, the numbers of current and former smokers in the USA and globally are not expected to decrease significantly in the near future. Chemoprevention and interception are needed to help high-risk individuals reduce their lung cancer risk or delay lung cancer development. This article will review the epidemiological data, pre-clinical animal data, and limited clinical data that support the potential of kava in reducing human lung cancer risk via its holistic polypharmacological effects. To facilitate its future clinical translation, advanced knowledge is needed with respect to its mechanisms of action and the development of mechanism-based non-invasive biomarkers in addition to safety and efficacy in more clinically relevant animal models.

Phe354Leu polymorphism of the liver kinase B1 gene as a prognostic factor in adult egyptian patients with acute myeloid leukemia

Background

The human liver kinase B1 (LKB1) gene is a significant tumor suppressor widely expressed in all fetal and adult tissues. Despite its established role in solid tumors, the biological and clinical implications of LKB1 gene alterations in hematological malignancies have not been sufficiently recognized.

Aim

This study aimed to determine the frequency of the LKB1 Phe354Leu polymorphism in adult Egyptian patients with cytogenetically normal AML (CN-AML), evaluate its clinical prognostic significance, and investigate its effect on the therapeutic outcome and patient survival.

Methods

Direct sequencing of amplified exon eight of the LKB1 gene was performed to detect the Phe354Leu polymorphism in 72 adult de novo CN-AML patients.

Results

The LKB1 Phe354Leu polymorphism was detected in 16.7% of patients and associated with younger age and lower hemoglobin levels (p < 0.001). Patients in the mutated group had significantly higher total leukocytic count and bone marrow blasts (p = 0.001 and p < 0.001, respectively). The most common FAB subtypes in mutated patients were M4 and M2. The relapse rate was significantly higher in the mutated group (p = 0.004). There was a significant association between the FLT3-ITD polymorphism and LKB1 F354L (p < 0.001). The mutated group had shorter overall survival (p = 0.003). In multivariate analysis, the Phe354Leu polymorphism was a significant independent prognostic variable for the overall and disease-free survival of the studied patients (p = 0.049).

Conclusion

The LKB1 Phe354Leu polymorphism was diagnosed at younger ages in Egyptian CN-AML patients and represented a poor independent prognostic factor in CN-AML. Patients who carried this polymorphism had shorter overall survival and more frequent relapses. Our findings may provide insight into the design of therapeutic targets, and molecular testing of the LKB1 gene is recommended for proper risk stratification of CN-AML patients.

Loss of liver kinase B1 in human seminoma

Testicular cancer is a common malignancy of young males and is believed to be originated from defective embryonic or adult germ cells. Liver kinase B1 (LKB1) is a serine/threonine kinase and a tumor suppressor gene. LKB1 is a negative regulator of the mammalian target of rapamycin (mTOR) pathway, often inactivated in many human cancer types. In this study, we investigated the involvement of LKB1 in the pathogenesis of testicular germ cell cancer. We performed immunodetection of LKB1 protein in human seminoma samples. A 3D culture model of human seminoma was developed from TCam-2 cells, and two mTOR inhibitors were tested for their efficacy against these cancer cells. Western blot and mTOR protein arrays were used to show that these inhibitors specifically target the mTOR pathway. Examination of LKB1 showed reduced expression in germ cell neoplasia in situ lesions and seminoma compared to adjacent normal-appearing seminiferous tubules where the expression of this protein was present in the majority of germ cell types. We developed a 3D culture model of seminoma using TCam-2 cells, which also showed reduced levels of LKB1 protein. Treatment of TCam-2 cells in 3D with two well-known mTOR inhibitors resulted in reduced proliferation and survival of TCam-2 cells. Overall, our results support that downregulation or loss of LKB1 marks the early stages of the pathogenesis of seminoma, and the suppression of downstream signaling to LKB1 might be an effective therapeutic strategy against this cancer type.

Phosphorylation of LKB1 by PDK1 Inhibits Cell Proliferation and Organ Growth by Decreased Activation of AMPK

The master kinase LKB1 is a key regulator of se veral cellular processes, including cell proliferation, cell polarity and cellular metabolism. It phosphorylates and activates several downstream kinases, including AMP-dependent kinase, AMPK. Activation of AMPK by low energy supply and phosphorylation of LKB1 results in an inhibition of mTOR, thus decreasing energy-consuming processes, in particular translation and, thus, cell growth. LKB1 itself is a constitutively active kinase, which is regulated by posttranslational modifications and direct binding to phospholipids of the plasma membrane. Here, we report that LKB1 binds to Phosphoinositide-dependent kinase (PDK1) by a conserved binding motif. Furthermore, a PDK1-consensus motif is located within the kinase domain of LKB1 and LKB1 gets phosphorylated by PDK1 in vitro. In Drosophila, knockin of phosphorylation-deficient LKB1 results in normal survival of the flies, but an increased activation of LKB1, whereas a phospho-mimetic LKB1 variant displays decreased AMPK activation. As a functional consequence, cell growth as well as organism size is decreased in phosphorylation-deficient LKB1. Molecular dynamics simulations of PDK1-mediated LKB1 phosphorylation revealed changes in the ATP binding pocket, suggesting a conformational change upon phosphorylation, which in turn can alter LKB1's kinase activity. Thus, phosphorylation of LKB1 by PDK1 results in an inhibition of LKB1, decreased activation of AMPK and enhanced cell growth.

LKB1 Loss Assessed by Immunohistochemistry as a Prognostic Marker to First-Line Therapy in Advanced Non-Small-Cell Lung Cancer

(1) Background: Liver kinase B1 (LKB1) is a tumor suppressor gene involved in cell growth and metabolism. However, its alterations are not routinely assessed for guiding therapy in clinical practice. We assessed LKB1 expression by immunohistochemistry as a potential biomarker. (2) Methods: This bicentric retrospective cohort study analyzed data from patients with advanced NSCLC who initiated platinum-based chemotherapy or epidermal growth factor receptor- tyrosine kinase inhibitor (EGFR-TKI) between January 2016 and December 2020. Kaplan-Meier and Cox regression models were used for survival curves and multivariate analysis. (3) Results: 110 patients were evaluated, and the clinical stage IV predominated the lung adenocarcinoma histology. LKB1 loss was observed in 66.3% of cases. LKB1 loss was associated with non-smokers, the absence of wood smoke exposure and an EGFR wild-type status. The median progression-free survival (PFS) and overall survival (OS) in the population were 11.1 and 26.8 months, respectively, in the loss group, compared with cases exhibiting a positive expression. After an adjustment by age, smoking status, Eastern Cooperative Oncology Group Performance Score (ECOG-PS), EGFR status and type of administered therapy, LKB1 loss was significantly associated with worse PFS and OS. (4) Conclusion: Patients with an LKB1 loss had worse clinical outcomes. This study warrants prospective assessments to confirm the prognostic role of the LKB1 expression in advanced NSCLC.

Genetic variants in LKB1/AMPK/mTOR pathway are associated with clinical outcomes of chemotherapy in non-small cell lung cancer

This study was conducted to investigate the relationship between genetic variants in LKB1/AMPK/mTOR pathway and treatment outcomes of patients with non-small cell lung cancer (NSCLC) treated with chemotherapy. A total of 379 patients with NSCLC who underwent first-line paclitaxel-cisplatin chemotherapy was enrolled. The associations between 19 single nucleotide variants (SNVs) in the LKB1/AMPK/mTOR pathway and the chemotherapy response and overall survival (OS) were analyzed. Among the SNVs analyzed, AKT1 rs2494750G>C and TSC1 rs2809244C>A were associated with clinical outcomes after chemotherapy in multivariate analyses. The AKT1 rs2494750G>C was significantly associated with a better response to chemotherapy (adjusted odds ratio [aOR]: 1.92, 95% confidence interval [CI]: 1.02-3.62, p = 0.04). The TSC1 rs2809244C>A were significantly associated with better OS (adjusted hazard ratio [aHR]: 0.79, 95% CI: 0.62-0.99, p = 0.04). When stratified by tumor histology, AKT1 rs2494750G>C exhibited a significant association with the chemotherapy response only in adenocarcinoma and TSC1 rs2809244C>A was also significantly associated with OS only in adenocarcinoma. This result suggests that the AKT1 rs2494750G>C and TSC1 rs2809244 C>A may be useful for predicting the clinical outcome of first-line paclitaxel-cisplatin chemotherapy in NSCLC.

The Distinct Roles of LKB1 and AMPK in p53-Dependent Apoptosis Induced by Cisplatin

Liver kinase B1 (LKB1) is a serine/threonine protein kinase that acts as a key tumor suppressor protein by activating its downstream kinases, such as AMP-activated protein kinase (AMPK). However, the regulatory actions of LKB1 and AMPK on DNA damage response (DDR) remain to be explored. In this study, we investigated the function of LKB1 in DDR induced by cisplatin, a representative DNA-damaging agent, and found that LKB1 stabilizes and activates p53 through the c-Jun N-terminal kinase (JNK) pathway, which promotes cisplatin-induced apoptosis in human fibrosarcoma cell line HT1080. On the other hand, we found that AMPKα1 and α2 double knockout (DKO) cells showed enhanced stabilization of p53 and increased susceptibility to apoptosis induced by cisplatin, suggesting that AMPK negatively regulates cisplatin-induced apoptosis. Moreover, the additional stabilization of p53 and subsequent apoptosis in AMPK DKO cells were clearly canceled by the treatment with the antioxidants, raising the possibility that AMPK suppresses the p53 activation mediated by oxidative stress. Thus, our findings unexpectedly demonstrate the reciprocal regulation of p53 by LKB1 and AMPK in DDR, which provides insights into the molecular mechanisms of DDR.

LKB1 phosphorylation and deactivation in lung cancer by NNAL, a metabolite of tobacco-specific carcinogen, in an isomer-dependent manner

LKB1 loss of function is one key oncogenic event in lung cancer. Clinical data suggest that LKB1 loss of function is associated with patients' smoking status. The responsible ingredients and molecular mechanisms in tobacco for LKB1 loss of function, however, are not defined. In this study, we reported that NNAL, a major metabolite of a tobacco-specific carcinogen NNK, induces LKB1 phosphorylation and its loss of function via the β-AR/PKA signaling pathway in an isomer-dependent manner in human lung cancer cells. NNAL exposure also resulted in enhanced lung cancer cell migration and chemoresistance in an LKB1-dependent manner. A 120-day NNAL exposure in lung cancer cells, mimicking its chronic exposure among smokers, resulted in more prominent LKB1 phosphorylation, cell migration, and chemoresistance even in the absence of NNAL, indicating the long-lasting LKB1 loss of function although such an effect eventually disappeared after NNAL was removed for two months. These observations were confirmed in a lung cancer xenograft model. More importantly, human lung cancer tissues revealed elevated LKB1 phosphorylation in comparison to the paired normal lung tissues. These results suggest that LKB1 loss of function in human lung cancer could be extended to its phosphorylation, which may be mediated by NNAL from tobacco smoke in an isomer-dependent manner via the β-AR/PKA signaling pathway.

Clinical characteristics and prognostic analysis of multiple primary malignant neoplasms in female patients with breast cancer or genitalia malignancies

Background

As public awareness of health has increased and diagnostic and treatment options have improved, the survival of patients with malignant tumors has continued to extend, and the population has been aging, the number of multiple primary malignant neoplasms has gradually increased in recent years. There are few reports concerning female patients with multiple primary malignant neoplasms of breast cancer or genitalia malignancies. In this study, we aimed to analyze the clinical characteristics and prognosis of multiple primary malignant neoplasms in female patients with breast cancer or genitalia malignancies, as well as further explore the factors that affect the survival.

Methods

We collected clinical data on 80 female patients diagnosed with multiple primary malignant neoplasms of the breast or genitalia, described their clinical features. Furthermore, we calculated the survival and prognostic factors for 52 participants.

Results

In our study, the prevalence rate of multiple primary malignant neoplasms was 0.66% (367/55404). Corresponding to female patients with multiple primary malignant neoplasms of breast cancer or genitalia malignancies, it was 1.4% (80/5707). the median age of diagnosis for the first tumor was 48 years, and the median age of diagnosis for the second tumor was 52 years. Regarding the interval, 67.57% (50/74) of patients were within five years. Most tumors were located in the breast (44.68%), followed by the uterus (20.21%), the ovary (17.02%), and the cervix (15.96%). The overall 12-, 36-and 60-month survival rates of the patients were 86.4%, 74.3%, and 69.8%. For the female patients, the stage (III-IV) (P = 0.046), non-radical surgery (P = 0.002), and types of the last tumor (breast cancer or genitalia malignancies) (P = 0.019) were associated with the poor prognosis.

Conclusions

Female patients with breast cancer or genital malignancies should pay attention to screening for the second tumor, especially within 4 years after the first tumor diagnosed. Furthermore, during tumor screening, it may be recommended for these patients to focus on colorectal cancer and lung cancer. Compared with previous studies, in addition to clinical staging and types of surgery, we found whether the last tumor was breast cancer or genitalia malignancies should also be considered a prognostic factor.

LKB1: Can We Target an Hidden Target? Focus on NSCLC

LKB1 (liver kinase B1) is a master regulator of several processes such as metabolism, proliferation, cell polarity and immunity. About one third of non-small cell lung cancers (NSCLCs) present LKB1 alterations, which almost invariably lead to protein loss, resulting in the absence of a potential druggable target. In addition, LKB1-null tumors are very aggressive and resistant to chemotherapy, targeted therapies and immune checkpoint inhibitors (ICIs). In this review, we report and comment strategies that exploit peculiar co-vulnerabilities to effectively treat this subgroup of NSCLCs. LKB1 loss leads to an enhanced metabolic avidity, and treatments inducing metabolic stress were successful in inhibiting tumor growth in several preclinical models. Biguanides, by compromising mitochondria and reducing systemic glucose availability, and the glutaminase inhibitor telaglenastat (CB-839), inhibiting glutamate production and reducing carbon intermediates essential for TCA cycle progression, have provided the most interesting results and entered different clinical trials enrolling also LKB1-null NSCLC patients. Nutrient deprivation has been investigated as an alternative therapeutic intervention, giving rise to interesting results exploitable to design specific dietetic regimens able to counteract cancer progression. Other strategies aimed at targeting LKB1-null NSCLCs exploit its pivotal role in modulating cell proliferation and cell invasion. Several inhibitors of LKB1 downstream proteins, such as mTOR, MEK, ERK and SRK/FAK, resulted specifically active on LKB1-mutated preclinical models and, being molecules already in clinical experimentation, could be soon proposed as a specific therapy for these patients. In particular, the rational use in combination of these inhibitors represents a very promising strategy to prevent the activation of collateral pathways and possibly avoid the potential emergence of resistance to these drugs. LKB1-null phenotype has been correlated to ICIs resistance but several studies have already proposed the mechanisms involved and potential interventions. Interestingly, emerging data highlighted that LKB1 alterations represent positive determinants to the new KRAS specific inhibitors response in KRAS co-mutated NSCLCs. In conclusion, the absence of the target did not block the development of treatments able to hit LKB1-mutated NSCLCs acting on several fronts. This will give patients a concrete chance to finally benefit from an effective therapy.

Role of STK11 in ALK-positive non-small cell lung cancer

Anaplastic lymphoma kinase (ALK) inhibitors have been shown to be effective in treating patients with ALK-positive non-small cell lung cancer (NSCLC), and crizotinib, ceritinib and alectinib have been approved as clinical first-line therapeutic agents. The availability of these inhibitors has also largely changed the treatment strategy for advanced ALK-positive NSCLC. However, patients still inevitably develop resistance to ALK inhibitors, leading to tumor recurrence or metastasis. The most critical issues that need to be addressed in the current treatment of ALK-positive NSCLC include the high cost of targeted inhibitors and the potential for increased toxicity and resistance to combination therapy. Recently, it has been suggested that the serine/threonine kinase 11 (STK11) mutation may serve as one of the biomarkers for immunotherapy in NSCLC. Therefore, the main purpose of this review was to summarize the role of STK11 in ALK-positive NSCLC. The present review also summarizes the treatment and drug resistance studies in ALK-positive NSCLC and the current status of STK11 research in NSCLC.

The Tumor Suppressor Kinase LKB1: Metabolic Nexus

Liver kinase B1 (LKB1) is a multitasking tumor suppressor kinase that is implicated in multiple malignancies such as lung, gastrointestinal, pancreatic, and breast. LKB1 was first identified as the gene responsible for Peutz-Jeghers syndrome (PJS) characterized by hamartomatous polyps and oral mucotaneous pigmentation. LKB1 functions to activate AMP-activated protein kinase (AMPK) during energy stress to shift metabolic processes from active anabolic pathways to active catabolic pathways to generate ATP. Genetic loss or inactivation of LKB1 promotes metabolic reprogramming and metabolic adaptations of cancer cells that fuel increased growth and division rates. As a result, LKB1 loss is associated with increased aggressiveness and treatment options for patients with LKB1 mutant tumors are limited. Recently, there has been new insights into the role LKB1 has on metabolic regulation and the identification of potential vulnerabilities in LKB1 mutant tumors. In this review, we discuss the tumor suppressive role of LKB1 and the impact LKB1 loss has on metabolic reprograming in cancer cells, with a focus on lung cancer. We also discuss potential therapeutic avenues to treat malignancies associated with LKB1 loss by targeting aberrant metabolic pathways associated with LKB1 loss.

LKB1 drives stasis and C/EBP-mediated reprogramming to an alveolar type II fate in lung cancer

LKB1 is among the most frequently altered tumor suppressors in lung adenocarcinoma. Inactivation of Lkb1 accelerates the growth and progression of oncogenic KRAS-driven lung tumors in mouse models. However, the molecular mechanisms by which LKB1 constrains lung tumorigenesis and whether the cancer state that stems from Lkb1 deficiency can be reverted remains unknown. To identify the processes governed by LKB1 in vivo, we generated an allele which enables Lkb1 inactivation at tumor initiation and subsequent Lkb1 restoration in established tumors. Restoration of Lkb1 in oncogenic KRAS-driven lung tumors suppressed proliferation and led to tumor stasis. Lkb1 restoration activated targets of C/EBP transcription factors and drove neoplastic cells from a progenitor-like state to a less proliferative alveolar type II cell-like state. We show that C/EBP transcription factors govern a subset of genes that are induced by LKB1 and depend upon NKX2-1. We also demonstrate that a defining factor of the alveolar type II lineage, C/EBPα, constrains oncogenic KRAS-driven lung tumor growth in vivo. Thus, this key tumor suppressor regulates lineage-specific transcription factors, thereby constraining lung tumor development through enforced differentiation.

Rare Hereditary Gynecological Cancer Syndromes

Hereditary cancer syndromes, which are characterized by onset at an early age and an increased risk of developing certain tumors, are caused by germline pathogenic variants in tumor suppressor genes and are mostly inherited in an autosomal dominant manner. Therefore, hereditary cancer syndromes have been used as powerful models to identify and characterize susceptibility genes associated with cancer. Furthermore, clarification of the association between genotypes and phenotypes in one disease has provided insights into the etiology of other seemingly different diseases. Molecular genetic discoveries from the study of hereditary cancer syndrome have not only changed the methods of diagnosis and management, but have also shed light on the molecular regulatory pathways that are important in the development and treatment of sporadic tumors. The main cancer susceptibility syndromes that involve gynecologic cancers include hereditary breast and ovarian cancer syndrome as well as Lynch syndrome. However, in addition to these two hereditary cancer syndromes, there are several other hereditary syndromes associated with gynecologic cancers. In the present review, we provide an overview of the clinical features, and discuss the molecular genetics, of four rare hereditary gynecological cancer syndromes; Cowden syndrome, Peutz-Jeghers syndrome, DICER1 syndrome and rhabdoid tumor predisposition syndrome 2.

Inactivation of AMPK Leads to Attenuation of Antigen Presentation and Immune Evasion in Lung Adenocarcinoma

PURPOSE

Mutations in STK11 (LKB1) occur in 17% of lung adenocarcinoma (LUAD) and drive a suppressive (cold) tumor immune microenvironment (TIME) and resistance to immunotherapy. The mechanisms underpinning the establishment and maintenance of a cold TIME in LKB1-mutant LUAD remain poorly understood. In this study, we investigated the role of the LKB1 substrate AMPK in immune evasion in human non-small cell lung cancer (NSCLC) and mouse models and explored the mechanisms involved.

EXPERIMENTAL DESIGN

We addressed the role of AMPK in immune evasion in NSCLC by correlating AMPK phosphorylation and immune-suppressive signatures and by deleting AMPKα1 (Prkaa1) and AMPKα2 (Prkaa2) in a Kras^G12D -driven LUAD. Furthermore, we dissected the molecular mechanisms involved in immune evasion by comparing gene-expression signatures, AMPK activity, and immune infiltration in mouse and human LUAD and gain or loss-of-function experiments with LKB1- or AMPK-deficient cell lines.

RESULTS

Inactivation of both AMPKα1 and AMPKα2 together with Kras activation accelerated tumorigenesis and led to tumors with reduced infiltration of CD8⁺/CD4⁺ T cells and gene signatures associated with a suppressive TIME. These signatures recapitulate those in Lkb1-deleted murine LUAD and in LKB1-deficient human NSCLC. Interestingly, a similar signature is noted in human NSCLC with low AMPK activity. In mechanistic studies, we find that compromised LKB1 and AMPK activity leads to attenuated antigen presentation in both LUAD mouse models and human NSCLC.

CONCLUSIONS

The results provide evidence that the immune evasion noted in LKB1-inactivated lung cancer is due to subsequent inactivation of AMPK and attenuation of antigen presentation.

Modulating Tumor Microenvironment: A Review on STK11 Immune Properties and Predictive vs Prognostic Role for Non-small-cell Lung Cancer Immunotherapy

The quest for immunotherapy (IT) biomarkers is an element of highest clinical interest in both solid and hematologic tumors. In non-small-cell lung cancer (NSCLC) patients, besides PD-L1 expression evaluation with its intrinsic limitations, tissue and circulating parameters, likely portraying the tumor and its stromal/immune counterparts, have been proposed as potential predictors of IT responsiveness. STK11 mutations have been globally labeled as markers of IT resistance. After a thorough literature review, STK11 mutations condition the prognosis of NSCLC patients receiving ICI-containing regimens, implying a relevant biological and clinical significance. On the other hand, waiting for prospective and solid data, the putative negative predictive value of STK11 inactivation towards IT is sustained by less evidence. The physiologic regulation of multiple cellular pathways performed by STK11 likely explains the multifaceted modifications in tumor cells, stroma, and tumor immune microenvironment (TIME) observed in STK11 mutant lung cancer, particularly explored in the molecular subgroup of KRAS co-mutation. IT approaches available thus far in NSCLC, mainly represented by anti-PD-1/PD-L1 inhibitors, are not promising in the case of STK11 inactivation. Perceptive strategies aimed at modulating the TIME, regardless of STK11 status or specifically addressed to STK11-mutated cases, will hopefully provide valid therapeutic options to be adopted in the clinical practice.

Gene of the month: STK11

STK11 encodes for the protein liver kinase B1, a serine/threonine kinase which is involved in a number of physiological processes including regulation of cellular metabolism, cell polarity and the DNA damage response. It acts as a tumour suppressor via multiple mechanisms, most classically through AMP-activated protein kinase-mediated inhibition of the mammalian target of rapamycin signalling pathway. Germline loss-of-function mutations in STK11 give rise to Peutz-Jeghers syndrome, which is associated with hamartomatous polyps of the gastrointestinal tract, mucocutaneous pigmentation and a substantially increased lifetime risk of many cancers. In the sporadic setting, STK11 mutations are commonly seen in a subset of adenocarcinomas of the lung in addition to a number of other tumours occurring at various sites. Mutations in STK11 have been associated with worse prognoses across a range of malignancies and may be a predictor of poor response to immunotherapy in a subset of lung cancers, though further studies are needed before the presence of STK11 mutations can be implemented as a routine clinical biomarker.

Biomarkers of Targeted Therapy and Immuno-Oncology in Cancers Metastatic to the Breast

The breast is a rare site for metastases, and their molecular characteristics have not been studied yet. Intrinsic molecular genetics, cancer characteristics, and breast tissue immune responses in diverse metastases to the breast have not been previously studied. We identified 64 patients with cancers metastatic to the breast: 51 carcinomas and 13 melanomas. Programmed death ligand 1 (PD-L1), steroid receptors, and HER2/neu expressions were evaluated using immunohistochemistry. Gene sequencing, copy number alterations, microsatellite instability, and tumor mutational burden were performed using next-generation sequencing platforms. The 3 most common primary sites for metastatic carcinomas were lung (37%), ovary (29%), and fallopian tubes/peritoneum (14%). TP53 mutations were commonly (50%) observed among the carcinoma cases, while other mutations were characteristic for the primary cancers (VHL in renal, BRCA1 in the fallopian tube, and BRAF in melanomas). High tumor mutational burden was detected in 5/14 carcinomas and 3/7 melanomas. Tumor cell PD-L1 expression was detected in 6 carcinomas, but not in any of the melanomas, whereas immune cells' expression of PD-L1 was seen in 17 carcinomas and 6 melanomas. Estrogen receptor status was positive in 13/49 carcinomas including 12 adenocarcinomas originating from the ovary and fallopian tube or peritoneum and 1 duodenal neuroendocrine carcinoma. No carcinoma was HER2/neu positive. Intrinsic genetic characteristics of the metastases to the breast followed the pattern commonly seen in primary tumors. Biomarkers of potential benefit to immune checkpoint inhibition therapy were limited to PD-L1-positive non-small cell lung cancer. No common characteristics of the heterogeneous group of tumor metastases to this organ were identified.

LKB1 inactivation modulates chromatin accessibility to drive metastatic progression

Metastasis is the leading cause of cancer-related deaths and enables cancer cells to compromise organ function by expanding in secondary sites. Since primary tumours and metastases often share the same constellation of driver mutations, the mechanisms that drive their distinct phenotypes are unclear. Here we show that inactivation of the frequently mutated tumour suppressor gene LKB1 (encoding liver kinase B1) has evolving effects throughout the progression of lung cancer, which leads to the differential epigenetic re-programming of early-stage primary tumours compared with late-stage metastases. By integrating genome-scale CRISPR-Cas9 screening with bulk and single-cell multi-omic analyses, we unexpectedly identify LKB1 as a master regulator of chromatin accessibility in lung adenocarcinoma primary tumours. Using an in vivo model of metastatic progression, we further show that loss of LKB1 activates the early endoderm transcription factor SOX17 in metastases and a metastatic-like sub-population of cancer cells within primary tumours. The expression of SOX17 is necessary and sufficient to drive a second wave of epigenetic changes in LKB1-deficient cells that enhances metastatic ability. Overall, our study demonstrates how the downstream effects of an individual driver mutation can change throughout cancer development, with implications for stage-specific therapeutic resistance mechanisms and the gene regulatory underpinnings of metastatic evolution.

Resistance to durvalumab and durvalumab plus tremelimumab is associated with functional STK11 mutations in non-small-cell lung cancer patients and is reversed by STAT3 knockdown

Mutations in the STK11 (LKB1) gene regulate resistance to PD-1/PD-L1 blockade. This study evaluated this association in patients with nonsquamous non-small-cell lung cancer enrolled in three Phase 1/2 trials. STK11 mutations were associated with resistance to the anti-PD-L1 antibody durvalumab (alone/with the anti-CTLA-4 antibody tremelimumab) independently of KRAS mutational status, highlighting STK11 as a potential driver of resistance to checkpoint blockade. Retrospective assessments of tumor tissue, whole blood and serum revealed a unique immune phenotype in patients with STK11 mutations, with increased expression of markers associated with neutrophils (i.e. CXCL2, IL6), Th17 contexture (i.e. IL17A) and immune checkpoints. Associated changes were observed in the periphery. Reduction of STAT3 in the tumor microenvironment using an antisense oligonucleotide reversed immunotherapy resistance in preclinical STK11 knockout models. These results suggest that STK11 mutations may hinder response to checkpoint blockade through mechanisms including suppressive myeloid cell biology, which could be reversed by STAT3-targeted therapy.

PIM kinases inhibit AMPK activation and promote tumorigenicity by phosphorylating LKB1

BACKGROUND

The oncogenic PIM kinases and the tumor-suppressive LKB1 kinase have both been implicated in the regulation of cell growth and metabolism, albeit in opposite directions. Here we investigated whether these kinases interact with each other to influence AMPK activation and tumorigenic growth of prostate and breast cancer cells.

METHODS

We first determined how PIM and LKB1 kinases affect AMPK phosphorylation levels. We then used in vitro kinase assays to demonstrate that LKB1 is phosphorylated by PIM kinases, and site-directed mutagenesis to identify the PIM target sites in LKB1. The cellular functions of PIM and LKB1 kinases were evaluated using either pan-PIM inhibitors or CRISPR/Cas9 genomic editing, with which all three PIM family members and/or LKB1 were knocked out from PC3 prostate and MCF7 breast cancer cell lines. In addition to cell proliferation assays, we examined the effects of PIM and/or LKB1 loss on tumor growth using the chick embryo chorioallantoic membrane (CAM) xenograft model.

RESULTS

We provide both genetic and pharmacological evidence to demonstrate that inhibition of PIM expression or activity increases phosphorylation of AMPK at Thr172 in both PC3 and MCF7 cells, but not in their derivatives lacking LKB1. This is explained by our observation that all three PIM family kinases can phosphorylate LKB1 at Ser334. Wild-type LKB1, but not its phosphodeficient derivative, can restore PIM inhibitor-induced AMPK phosphorylation in LKB1 knock-out cells. In the CAM model, loss of LKB1 enhances tumorigenicity of PC3 xenografts, while cells lacking both LKB1 and PIMs exhibit slower proliferation rates and form smaller tumors.

CONCLUSION

PIM kinases are novel negative regulators of LKB1 that affect AMPK activity in an LKB1-dependent fashion. The impairment of cell proliferation and tumor growth in cells lacking both LKB1 and PIMs indicates that these kinases possess a shared signaling role in the context of cancer. These data also suggest that PIM inhibitors may be a rational therapeutic option for LKB1-deficient tumors. Video Abstract.

STK11 alterations in the pan-cancer setting: prognostic and therapeutic implications

BACKGROUND

STK11 is an important tumour suppressor gene reported to confer immunotherapy resistance in non-small-cell lung cancers (NSCLC) especially in the presence of KRAS co-alterations.

METHODS

This study analysed 4446 patients for whom next-generation sequencing of tissue and/or circulating tumour DNA (ctDNA) had been performed.

RESULTS

Overall, 60 of 4446 tumours (1.35%) harboured STK11 alterations. STK11 alterations were associated with shorter median time to progression and overall survival (OS) across cancers from diagnosis: 6.4 months (5.1-7.9) versus 12 months (11.7-12.3; p = 0.001); and 20.5 (17.4-23.5) versus 29.1 (26.9-31.3; p = 0.03), respectively (pan-cancer). Pan-cancers, the median progression-free survival (PFS; 95% CI) for first-line therapy (regardless of treatment type) for those with co-altered STK11 and KRAS (N = 27; versus STK11-altered and KRAS wild type [N = 33]), was significantly shorter (3 [1.3-4.7] versus 10 [4.9-15.7] months, p < 0.0005, p multivariate, 0.06); the median OS also was also shorter (p multivariate = 0.02). In pan-cancer patients treated with checkpoint blockade, STK11 and KRAS co-altered versus STK11-altered/KRAS wild type had a shorter median PFS and trend toward shorter OS (p = 0.04 and p = 0.06, respectively). In contrast, in examining STK11-altered versus wild-type pan-cancer patients treated with checkpoint blockade immunotherapy, the two groups showed no difference in outcome (PFS [p = 0.4]; OS [p = 0.7]); STK11-altered versus wild-type lung cancer patients also did not fare worse on immunotherapy.

CONCLUSIONS

Across cancers, STK11 alterations correlated with a poor prognosis regardless of therapy. However, STK11 alterations alone did not associate with inferior immunotherapy outcome in the pan-cancer setting or in NSCLC. Pan-cancer patients with co-altered STK11/KRAS did worse, regardless of treatment type.

Inhibition of β-Catenin Activity Abolishes LKB1 Loss-Driven Pancreatic Cystadenoma in Mice

Pancreatic cancer (PC) is the seventh leading cause of cancer death worldwide, and remains one of our most recalcitrant and dismal diseases. In contrast to many other malignancies, there has not been a significant improvement in patient survival over the past decade. Despite advances in our understanding of the genetic alterations associated with this disease, an incomplete understanding of the underlying biology and lack of suitable animal models have hampered efforts to develop more effective therapies. LKB1 is a tumor suppressor that functions as a primary upstream kinase of adenine monophosphate-activated protein kinase (AMPK), which is an important mediator in the regulation of cell growth and epithelial polarity pathways. LKB1 is mutated in a significant number of Peutz–Jeghers syndrome (PJS) patients and in a small proportion of sporadic cancers, including PC; however, little is known about how LKB1 loss contributes to PC development. Here, we report that a reduction in Wnt/β-catenin activity is associated with LKB1 tumor-suppressive properties in PC. Remarkably, in vivo functional analyses of β-catenin in the Pdx-1-Cre LKB1^L/L β-catenin^L/L mouse model compared to LKB1 loss-driven cystadenoma demonstrate that the loss of β-catenin impairs cystadenoma development in the pancreas of Pdx-1Cre LKB1^L/L mice and dramatically restores the normal development and functions of the pancreas. This study further determined the in vivo and in vitro therapeutic efficacy of the β-catenin inhibitor FH535 in suppressing LKB1 loss-driven cystadenoma and reducing PC progression that delineates the potential roles of Wnt/β-catenin signaling in PC harboring LKB1 deficiency.

LKB1 Down-Modulation by miR-17 Identifies Patients With NSCLC Having Worse Prognosis Eligible for Energy-Stress-Based Treatments

INTRODUCTION

Preclinical models recently unveiled the vulnerability of LKB1/KRAS comutated NSCLC to metabolic stress-based treatments. Because miR-17 is a potential epigenetic regulator of LKB1, we hypothesized that wild-type LKB1 (LKB1^WT) NSCLC with high miR-17 expression may be sensitive to an energetic stress condition, and eligible for metabolic frailties-based therapeutic intervention.

METHODS

We took advantage of NSCLC cell lines with different combinations of KRAS mutation and LKB1 deletion and of patient-derived xenografts (PDXs) with high (LKB1^WT/miR-17 high) or low (LKB1^WT/miR-17 low) miR-17 expression. We evaluated LKB1 pathway impairment and apoptotic response to metformin. We retrospectively evaluated LKB1 and miR-17 expression levels in tissue specimens of patients with NSCLC and PDXs. In addition, a lung cancer series from The Cancer Genome Atlas data set was analyzed for miR-17 expression and potential correlation with clinical features.

RESULTS

We identified miR-17 as an epigenetic regulator of LKB1 in NSCLC and confirmed targeting of miR-17 to LKB1 3' untranslated region by luciferase reporter assay. We found that miR-17 overexpression functionally impairs the LKB1/AMPK pathway. Metformin treatment prompted apoptosis on miR-17 overexpression only in LKB1^WT cell lines, and in LKB1^WT/miR-17 high PDXs. A retrospective analysis in patients with NSCLC revealed an inverse correlation between miR-17 and LKB1 expression and highlighted a prognostic role of miR-17 expression in LKB1^WT patients, which was further confirmed by The Cancer Genome Atlas data analysis.

CONCLUSIONS

We identified miR-17 as a mediator of LKB1 expression in NSCLC tumors. This study proposes a miR-17 expression score potentially exploitable to discriminate LKB1^WT patients with NSCLC with impaired LKB1 expression and poor outcome, eligible for energy-stress-based treatments.

AMPKα-like proteins as LKB1 downstream targets in cell physiology and cancer

One of the key events in cancer development is the ability of tumor cells to overcome nutrient deprivation and hypoxia. Among proteins performing metabolic adaptation to the various cellular nutrient conditions, liver kinase B 1 (LKB1) and its main downstream target adenosine monophosphate (AMP)-activated protein kinase α (AMPKα) are important sensors of energy requirements within the cell. Although LKB1 was originally described as a tumor suppressor, given its role in metabolism, it potentially acts as a double-edged sword. AMPKα, a master regulator of cell energy demands, is activated when ATP level drops under a certain threshold, responding accordingly through its downstream targets. Twelve downstream kinase targets of LKB1 have been described as AMPKα-like proteins. This group is comprised of novel (nua) kinase family (NUAK) kinases (NUAK1 and 2) linked to cell cycle progression and ultraviolet (UV)-damage; microtubule affinity regulating kinases (MARKs) (MARK1, MARK2, MARK3, and MARK4) that are involved in cell polarity; salt inducible kinases (SIK) (SIK1, SIK2, also known as Qin-induced kinase or QIK and SIK3) that are implicated in cell metabolism and adipose tissue development and mitotic regulation; maternal embryonic leuzine zipper kinase (MELK) that regulate oocyte maturation; and finally brain selective kinases (BRSKs) (BRSK1 and 2), which have been mainly characterized in the brain due to their role in neuronal polarization. Thus, many efforts have been made in order to harness LKB1 kinase and its downstream targets as a possible therapeutic hub in tumor development and propagation. In this review, we describe LKB1 and its downstream target AMPK summarize major functions of various AMPK-like proteins, while focusing on biological functions of BRSK1 and 2 in different models.

Beyond bevacizumab: a review of targeted agents in metastatic small bowel adenocarcinoma

Small bowel cancers are rare tumors with an incidence 50-100-fold less than colorectal cancer. These tumors carry a poor prognosis. Owing to its rarity, treatment of this disease, particularly in its advanced stages, has not been optimized and is derived mainly from treatment regimens for colorectal cancer. Based on recent studies bevacizumab, an antibody directed against vascular endothelial growth factor and used in the management of metastatic CRC, has been added to treatment guidelines for metastatic small bowel adenocarcinoma. We investigate in this review the evidence behind other targeted treatments that may be beneficial in the treatment of metastatic small bowel adenocarcinoma. These are agents against EGFR, VEGFR-2, HER2, and NTRK as well as immune checkpoint inhibitors. The last class of drugs appears to hold the greatest promise based on the preponderance of evidence supporting its use. However, overall data remains sparse. Results of studies currently underway will be valuable in shedding more light on the management of this aggressive cancer.

LKB1 and cancer: The dual role of metabolic regulation

Liver kinase B1 (LKB1) is an essential serine/threonine kinase frequently associated with Peutz-Jeghers syndrome (PJS). In this review, we provide an overview of the role of LKB1 in conferring protection to cancer cells against metabolic stress and promoting cancer cell survival and invasion. This carcinogenic effect contradicts the previous conclusion that LKB1 is a tumor suppressor gene. Here we try to explain the contradictory effect of LKB1 on cancer from a metabolic perspective. Upon deletion of LKB1, cancer cells experience increased energy as well as oxidative stress, thereby causing genomic instability. Meanwhile, mutated LKB1 cooperates with other metabolic regulatory genes to promote metabolic reprogramming that subsequently facilitates adaptation to strong metabolic stress, resulting in development of a more aggressive malignant phenotype. We aim to specifically discuss the contradictory role of LKB1 in cancer by reviewing the mechanism of LKB1 with an emphasis on metabolic stress and metabolic reprogramming.

LKB1/STK11 Expression in Lung Adenocarcinoma and Associations With Patterns of Recurrence

BACKGROUND

Mutations in the serine/threonine kinase 11 (STK11)/liver kinase B1 (LKB1) have been implicated in mediating resistance to checkpoint blockade among patients with advanced lung adenocarcinoma. We sought to examine the associations between clinicopathologic characteristics, tumor LKB1 expression, features of the immune microenvironment, and postoperative prognosis among patients with early stage lung adenocarcinoma undergoing surgical therapy.

METHODS

Formalin-fixed, paraffin-embedded specimens of patients undergoing resection of stage I to III, chemotherapy-naïve adenocarcinomas (1997 to 2008) were analyzed using tissue microarray sectioning. Sublobar resections were excluded. Intratumoral LKB1/STK11 expression was quantified as H-score. In a subset, tumor-associated immune cell populations were quantified using whole tumor sections in peritumoral and intratumoral compartments.

RESULTS

In all, 104 patients met inclusion criteria. Expression of LKB1/STK11 (median H-score 102.9) was higher in women (median 123.3) than in men (100, P = .004) and in never-smokers (median 145) than in former/current smokers (100, P = .002). Expression of LKB1/STK11 was positively correlated with intratumoral infiltration of cluster of differentiation (CD) 3⁺ (r = 0.351, P = .005), CD4⁺ (r = 0.436, P < .001), and CD8⁺ (r = 0.263, P = .049) cells. Patients with extrathoracic recurrence had lower tumor expression of LKB1/STK11 than did other patients with recurrent disease. On multivariate analysis, low LKB1/STK11 expression remained independently associated with poor disease-free survival and distant disease-free survival.

CONCLUSIONS

Low LKB1/STK11 expression is associated with specific patient characteristics and poor postoperative prognosis in chemotherapy-naïve lung adenocarcinoma. Further investigation is warranted to delineate its clinical significance in the context of evaluating novel therapeutic agents in patients with resectable disease.

The role of ubiquitination in tumorigenesis and targeted drug discovery

Ubiquitination, an important type of protein posttranslational modification (PTM), plays a crucial role in controlling substrate degradation and subsequently mediates the "quantity" and "quality" of various proteins, serving to ensure cell homeostasis and guarantee life activities. The regulation of ubiquitination is multifaceted and works not only at the transcriptional and posttranslational levels (phosphorylation, acetylation, methylation, etc.) but also at the protein level (activators or repressors). When regulatory mechanisms are aberrant, the altered biological processes may subsequently induce serious human diseases, especially various types of cancer. In tumorigenesis, the altered biological processes involve tumor metabolism, the immunological tumor microenvironment (TME), cancer stem cell (CSC) stemness and so on. With regard to tumor metabolism, the ubiquitination of some key proteins such as RagA, mTOR, PTEN, AKT, c-Myc and P53 significantly regulates the activity of the mTORC1, AMPK and PTEN-AKT signaling pathways. In addition, ubiquitination in the TLR, RLR and STING-dependent signaling pathways also modulates the TME. Moreover, the ubiquitination of core stem cell regulator triplets (Nanog, Oct4 and Sox2) and members of the Wnt and Hippo-YAP signaling pathways participates in the maintenance of CSC stemness. Based on the altered components, including the proteasome, E3 ligases, E1, E2 and deubiquitinases (DUBs), many molecular targeted drugs have been developed to combat cancer. Among them, small molecule inhibitors targeting the proteasome, such as bortezomib, carfilzomib, oprozomib and ixazomib, have achieved tangible success. In addition, MLN7243 and MLN4924 (targeting the E1 enzyme), Leucettamol A and CC0651 (targeting the E2 enzyme), nutlin and MI-219 (targeting the E3 enzyme), and compounds G5 and F6 (targeting DUB activity) have also shown potential in preclinical cancer treatment. In this review, we summarize the latest progress in understanding the substrates for ubiquitination and their special functions in tumor metabolism regulation, TME modulation and CSC stemness maintenance. Moreover, potential therapeutic targets for cancer are reviewed, as are the therapeutic effects of targeted drugs.

Effectiveness of Olaparib Treatment in a Patient with Gallbladder Cancer with an ATM-Inactivating Mutation

Here, we report a case of postoperative recurrence of gallbladder carcinoma (GBC) in a patient who declined systemic chemotherapy. ATM S1905Ifs*25 and STK11 K262Sfs*25 mutations were detected by next-generation sequencing. Oral administration of olaparib was initiated. One month later, the patient experienced relief of clinical symptoms, a decrease in CA19-9 level, and a reduction in abnormal signal in the subcapsular region. The tumor response remained stable for approximately 13 months. This is the first case to demonstrate the clinical benefits of olaparib treatment in a patient with GBC harboring an ATM-inactivating mutation. This observation helps to better inform treatment options to enhance the care of patients with advanced GBC. KEY POINTS: A patient with gallbladder carcinoma harboring an ATM-inactivating mutation responded to olaparib with a progression-free survival of 13 months. This is the first report that demonstrates the clinical benefits of olaparib treatment in a patient with gallbladder carcinoma with an ATM-inactivating mutation. It also highlights the importance of next-generation sequencing, which can provide valuable information for planning effective targeted therapies for gallbladder carcinoma. Evidence-based decisions help determine the best choice of treatment for individualized patient care.

An LKB1-SIK Axis Suppresses Lung Tumor Growth and Controls Differentiation

The kinase LKB1 is a critical tumor suppressor in sporadic and familial human cancers, yet the mechanisms by which it suppresses tumor growth remain poorly understood. To investigate the tumor-suppressive capacity of four canonical families of LKB1 substrates in vivo, we used CRISPR/Cas9-mediated combinatorial genome editing in a mouse model of oncogenic KRAS-driven lung adenocarcinoma. We demonstrate that members of the SIK family are critical for constraining tumor development. Histologic and gene-expression similarities between LKB1- and SIK-deficient tumors suggest that SIKs and LKB1 operate within the same axis. Furthermore, a gene-expression signature reflecting SIK deficiency is enriched in LKB1-mutant human lung adenocarcinomas and is regulated by LKB1 in human cancer cell lines. Together, these findings reveal a key LKB1-SIK tumor-suppressive axis and underscore the need to redirect efforts to elucidate the mechanisms through which LKB1 mediates tumor suppression. SIGNIFICANCE: Uncovering the effectors of frequently altered tumor suppressor genes is critical for understanding the fundamental driving forces of cancer growth. Our identification of the SIK family of kinases as effectors of LKB1-mediated tumor suppression will refocus future mechanistic studies and may lead to new avenues for genotype-specific therapeutic interventions.This article is highlighted in the In This Issue feature, p. 1469.

LKB1/AMPK Pathway and Drug Response in Cancer: A Therapeutic Perspective

Inactivating mutations of the tumor suppressor gene Liver Kinase B1 (LKB1) are frequently detected in non-small-cell lung cancer (NSCLC) and cervical carcinoma. Moreover, LKB1 expression is epigenetically regulated in several tumor types. LKB1 has an established function in the control of cell metabolism and oxidative stress. Clinical and preclinical studies support a role of LKB1 as a central modifier of cellular response to different stress-inducing drugs, suggesting LKB1 pathway as a highly promising therapeutic target. Loss of LKB1-AMPK signaling confers sensitivity to energy depletion and to redox homeostasis impairment and has been associated with an improved outcome in advanced NSCLC patients treated with chemotherapy. In this review, we provide an overview of the interplay between LKB1 and its downstream targets in cancer and focus on potential therapeutic strategies whose outcome could depend from LKB1.

Determinants of immunological evasion and immunocheckpoint inhibition response in non-small cell lung cancer: the genetic front

The incorporation into clinical practice of immune-checkpoint inhibitors (ICIs), such as those targeting the cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and the programmed cell death 1 (PD-1) and its ligand (PD-L1), has represented a major breakthrough in non-small cell lung cancer (NSCLC) treatment, especially in cases where the cancer has no druggable genetic alterations. Despite becoming the standard of care in certain clinical settings, either alone or in combination with chemotherapy, a proportion of patients do not respond while others actually progress during treatment. Therefore, there is a clinical need to identify accurate predictive biomarkers and to develop novel therapeutic strategies based on ICIs. Although they have limitations, the current markers evaluated to select which patients will undergo ICI treatment are the levels of PD-L1 and the tumor mutational burden. In this paper we describe what is currently known about the dynamic interaction between the cancer cell and the immune system during carcinogenesis, with a particular focus on the description of the functions and gene alterations that preclude the host immunoresponse in NSCLC. We emphasize the deleterious gene alterations in components of the major histocompatibility complex (HLA-I or B2M) and of the response to IFNγ (such as JAK2) which are mutually exclusive and can affect up to one fifth of the NSCLCs. The participation of other gene alterations, such as those of common oncogenes and tumor suppressors, and of the epigenetic alterations will also be discussed, in detail. Finally, we discuss the potential use of the tumor's genetic profile to predict sensitivity to ICIs.

Inactivation of Lkb1 in postnatal chondrocytes leads to epiphyseal growth-plate abnormalities and promotes enchondroma-like formation

Liver serine-threonine kinase B1 (LKB1) is a tumor suppressor that has been linked to many types of tumors. However, the role of LKB1 in cartilaginous tumorigenesis is still poorly understood. In this study, we find that cartilage-specific, tamoxifen-inducible Lkb1 knockout results in multiple enchondroma-like lesions adjacent to the disorganized growth plates. We showed that chondrocytes retain an immature status caused by loss of Lkb1, which may lead to the dramatic expansion of growth-plate cartilage and the formation of enchondroma-like lesions. Additionally, increased mammalian target of rapamycin complex 1 (mTORC1) activity is observed in the Lkb1 conditional knockout (cKO) chondrocytes, and rapamycin (mTORC1 inhibitor) treatment significantly alleviates the expansion of growth-plate cartilage and eliminates the enchondroma-like lesions in Lkb1 cKO mice. Thus, our findings indicate that loss of Lkb1 leads to the expansion of chondrocytes and the formation of enchondroma-like lesions during postnatal cartilage development, and that the up-regulated mTORC1-signaling pathway is implicated in this process. Our findings suggest that modulation of LKB1 and related signaling is a potential therapy in cartilaginous tumorigenesis.-Zhou, S., Li, Y., Qiao, L., Ge, Y., Huang, X., Gao, X., Ju, H., Wang, W., Zhang, J., Yan, J., Teng, H., Jiang, Q. Inactivation of Lkb1 in postnatal chondrocytes leads to epiphyseal growth-plate abnormalities and promotes enchondroma-like formation.

Loss of LKB1 Protein Expression Correlates with Increased Risk of Recurrence and Death in Patients with Resected, Stage II or III Colon Cancer

PURPOSE

The purpose of this study was to investigate the prognostic significance of liver kinase b1 (LKB1) loss in patients with operable colon cancer (CC).

Materials and Methods

Two hundred sixty-two specimens from consecutive patients with stage III or high-risk stage II CC, who underwent surgical resection with curative intent and received adjuvant chemotherapy with fluoropyrimidine and oxaliplatin, were analyzed for LKB1 protein expression loss, by immunohistochemistry as well as for KRAS exon 2 and BRAFV600E mutations by Sanger sequencing and TS, ERCC1, MYC, and NEDD9 mRNA expression by real-time quantitative reverse transcription polymerase chain reaction.

RESULTS

LKB1 expression loss was observed in 117 patients (44.7%) patients and correlated with right-sided located primaries (p=0.032), and pericolic lymph nodes involvement (p=0.003), BRAFV600E mutations (p=0.024), and TS mRNA expression (p=0.041). Patients with LKB1 expression loss experienced significantly lower disease-free survival (DFS) (hazard ratio [HR], 1.287; 95% confidence interval [CI], 1.093 to 1.654; p=0.021) and overall survival (OS) (HR, 1.541; 95% CI, 1.197 to 1.932; p=0.002), compared to patients with LKB1 expressing expressing tumors. Multivariate analysis revealed LKB1 expression loss as independent prognostic factor for both decreased DFS (HR, 1.217; 95% CI, 1.074 to 1.812; p=0.034) and decreased OS (HR, 1.467; 95% CI, 1.226 to 2.122; p=0.019).

CONCLUSION

Loss of tumoral LKB1 protein expression, constitutes an adverse prognostic factor in patients with operable CC.

Lkb1 deletion in periosteal mesenchymal progenitors induces osteogenic tumors through mTORC1 activation

Bone osteogenic sarcoma has a poor prognosis as the exact cell of origin and the signaling pathways underling tumor formation remain undefined. Here, we report an osteogenic tumor mouse model based on the conditional knockout of liver kinase b1 (Lkb1; also known as Stk11) in Cathepsin K (Ctsk)-Cre expressing cells. Lineage tracing studies demonstrated that Ctsk-Cre could label a population of periosteal cells. The cells functioned as mesenchymal progenitors with regard to markers and functional properties. LKB1 deficiency increased proliferation and osteoblast differentiation of Ctsk+ periosteal cells, while downregulation of mTORC1 activity, using Raptor genetic mouse model or mTORC1 inhibitor treatment, ameliorated tumor progression of Ctsk-Cre Lkb1fllfl mice. Xenograft mouse models, using human osteosarcoma cell lines, also demonstrated that LKB1 deficiency promoted tumor formation, while mTOR inhibition suppressed xenograft tumor growth. In summary, we identified periosteum-derived Ctsk-Cre expressing cells as a cell of origin for osteogenic tumor and suggested the LKB1-mTORC1 pathway as a promising target for treatment of osteogenic tumor.

Adaptive Transcriptional Responses by CRTC Coactivators in Cancer

Adaptive stress signaling networks directly influence tumor development and progression. These pathways mediate responses that allow cancer cells to cope with both tumor cell-intrinsic and cell-extrinsic insults and develop acquired resistance to therapeutic interventions. This is mediated in part by constant oncogenic rewiring at the transcriptional level by integration of extracellular cues that promote cell survival and malignant transformation. The cAMP-regulated transcriptional coactivators (CRTCs) are a newly discovered family of intracellular signaling integrators that serve as the conduit to the basic transcriptional machinery to regulate a host of adaptive response genes. Thus, somatic alterations that lead to CRTC activation are emerging as key driver events in the development and progression of many tumor subtypes.

LKB1 signaling is activated in CTNNB1-mutated HCC and positively regulates β-catenin-dependent CTNNB1-mutated HCC

Hepatocellular carcinomas (HCCs) are known to be highly heterogenous. Within the extensive histopathological and molecular heterogeneity of HCC, tumors with mutations in CTNNB1, encoding β-catenin (CTNNB1-mutated HCC), constitute a very homogeneous group. We previously characterized a distinctive metabolic and histological phenotype for CTNNB1-mutated HCC. They were found to be well-differentiated, almost never steatotic, and often cholestatic, with a microtrabecular or acinar growth pattern. Here, we investigated whether LKB1, which controls energy metabolism, cell polarity, and cell growth, mediates the specific phenotype of CTNNB1-mutated HCC. The LKB1 protein was overexpressed in CTNNB1-mutated HCC and oncogenic activation of β-catenin in human HCC cells induced the post-transcriptional accumulation of the LKB1 protein encoded by the LKB1 (STK11) gene. Hierarchical clustering, based on the expression of a murine hepatic liver Lkb1 (Stk11) signature in a human public dataset, identified a HCC cluster, composed of almost all the CTNNB1-mutated HCC, that expresses a hepatic liver LKB1 program. This was confirmed by RT-qPCR of an independent cohort of CTNNB1-mutated HCC and the suppression of the LKB1-related profile upon β-catenin silencing of CTNNB1-mutated human hepatoma cell lines. Previous studies described an epistatic relationship between LKB1 and CTNNB1 in which LKB1 acts upstream of CTNNB1. Thus, we also analyzed the consequences of Lkb1 deletion on the zonation of hepatic metabolism, known to be the hallmark of β-catenin signaling in the liver. Lkb1 was required for the establishment of metabolic zonation in the mouse liver by positively modulating β-catenin signaling. We identified positive reciprocal cross talk between the canonical Wnt pathway and LKB1, both in normal liver physiology and during tumorigenesis that likely participates in the amplification of the β-catenin signaling by LKB1 and the distinctive phenotype of the CTNNB1-mutated HCC. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.