Project description:Inherited mutation in LKB1 results in the Peutz-Jeghers syndrome (PJS), characterized by intestinal hamartomas and a modestly increased frequency of gastrointestinal and breast cancer1. Somatic inactivation of LKB1 occurs in human lung adenocarcinoma2-4, but its tumor suppressor role in this tissue is unknown. Here we show that somatic Lkb1 deficiency strongly cooperates with somatic K-rasG12D activating mutation to accelerate the development of mouse lung tumorigenesis. Lkb1 deficiency in the setting of K-rasG12D mutation (K-ras Lkb1L/L) was associated with decreased tumor latency and increased tumor aggressiveness including metastasis. Furthermore, tumors from K-ras Lkb1L/L mice demonstrated histologies--squamous, adenosquamous and large cell--not seen with K-rasG12D mutation, Ink4a/Arf inactivation, or p53 inactivation alone or in combination. Experiments in vitro suggest that LKB1 suppresses lung tumorigenesis and progression through both p16INK4a-ARF-p53 dependent and independent mechanisms. These data indicate that LKB1 regulates lung tumor progression and differentiation. Keywords: cancer research To analyze the role of LKB1 in lung cancer progression and differentiation, we have dissected the lung tumors from mice with/without lkb1 loss and performed the microarray analyses to compare their gene expression pattern. In addition, we have also performed microarray analysis in both A549 and H2126 cell lines after reconsistitution of either wt-lkb1 or the kinase dead form of lkb1 (lkb1-KD) to confirm what we observed from in vivo studies.
Project description:Inherited mutation in LKB1 results in the Peutz-Jeghers syndrome (PJS), characterized by intestinal hamartomas and a modestly increased frequency of gastrointestinal and breast cancer1. Somatic inactivation of LKB1 occurs in human lung adenocarcinoma2-4, but its tumor suppressor role in this tissue is unknown. Here we show that somatic Lkb1 deficiency strongly cooperates with somatic K-rasG12D activating mutation to accelerate the development of mouse lung tumorigenesis. Lkb1 deficiency in the setting of K-rasG12D mutation (K-ras Lkb1L/L) was associated with decreased tumor latency and increased tumor aggressiveness including metastasis. Furthermore, tumors from K-ras Lkb1L/L mice demonstrated histologies--squamous, adenosquamous and large cell--not seen with K-rasG12D mutation, Ink4a/Arf inactivation, or p53 inactivation alone or in combination. Experiments in vitro suggest that LKB1 suppresses lung tumorigenesis and progression through both p16INK4a-ARF-p53 dependent and independent mechanisms. These data indicate that LKB1 regulates lung tumor progression and differentiation. Keywords: cancer research
Project description:Group 2 innate lymphoid cells (ILC2s) mediate type 2 immune responses involved in anti-helminth immunity, allergic inflammation, and metabolic homeostasis. Recently, they have emerged as key players in regulating tumor immunity. The tumor suppressor liver kinase B1 (LKB1) inactivating mutations is associated with a variety of human cancers, but the role of LKB1 in ILC2 function and ILC2-mediated tumor immunity remains unknown. Here, we show that LKB1 is required for mature ILC2 survival. Ablation of LKB1 in ILC2s results in impaired proliferation and a marked decrease in type 2 cytokine production upon activation, accompanied with the expression of exhaustion signature genes and reduced cellular metabolism, which promote the development of lung melanoma metastasis. In addition, LKB1 deficiency leads to a marked increase of programmed cell death protein-1 (PD-1) expression in ILC2s through activation of nuclear factor of activated T cells (NFAT) pathway. Blockade of PD-1 can restore type 2 cytokine production in LKB1-deficient ILC2 and reverse its exhaustion state, leading to enhanced antitumor immune responses in vivo. Together, our results reveal that LKB1 retrains ILC2 exhaustion state to maintain immune homeostasis and their antitumor immunity.
Project description:Inherited mutation in LKB1 results in the Peutz-Jeghers syndrome (PJS), characterized by intestinal hamartomas and a modestly increased frequency of gastrointestinal and breast cancer1. Somatic inactivation of LKB1 occurs in human lung adenocarcinoma2-4, but its tumor suppressor role in this tissue is unknown. Here we show that somatic Lkb1 deficiency strongly cooperates with somatic K-rasG12D activating mutation to accelerate the development of mouse lung tumorigenesis. Lkb1 deficiency in the setting of K-rasG12D mutation (K-ras Lkb1L/L) was associated with decreased tumor latency and increased tumor aggressiveness including metastasis. Furthermore, tumors from K-ras Lkb1L/L mice demonstrated histologies--squamous, adenosquamous and large cell--not seen with K-rasG12D mutation, Ink4a/Arf inactivation, or p53 inactivation alone or in combination. Experiments in vitro suggest that LKB1 suppresses lung tumorigenesis and progression through both p16INK4a-ARF-p53 dependent and independent mechanisms. These data indicate that LKB1 regulates lung tumor progression and differentiation. Keywords: cancer research To analyze the role of LKB1 in lung cancer progression and differentiation, we have dissected the lung tumors from mice with/without lkb1 loss and performed the microarray analyses to compare their gene expression pattern. In addition, we have also performed microarray analysis in both A549 and H2126 cell lines after reconsistitution of either wt-lkb1 or the kinase dead form of lkb1 (lkb1-KD) to confirm what we observed from in vivo studies.
Project description: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 aggressive 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 during tumor development and subsequent Lkb1 restoration in established tumors. Restoration of Lkb1 in oncogenic KRAS-driven lung tumors suppressed proliferation and promoted tumor stasis. Lkb1 restoration activated targets of C/EBP transcription factors and drove the transition of 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. Thus, we uncover a role for a critical tumor suppressor in the regulation of key lineage-specific transcription factors, thereby constraining lung tumor development through the enforcement of differentiation.
Project description:LKB1 is a tumor suppressor lost in approximately 30% of lung adenocarcinomas. It is a serine-threonine kinase involved in regulating metabolism, proliferation, and cell polarity. We have characterized its association with mRNA expression profiles in resected tumors and in cell lines, but little is known about the direct effects of LKB1 on the regulation of these genes. This study investigates the effects of LKB1 activity on mRNA expression in two LKB1-mutant lung adenocarcinoma cell lines, H2122 and A549. Wild-type LKB1 has been stably expressed in these cell lines using a pBABE retrovirus as well as an empty pBABE control and a kinase-dead mutant of LKB1 (K78I) control (Addgene). Samples submitted are two cell lines, three experimental conditions, and three replicates, for a total of 17 samples (one sample was excluded for poor RNA quality). Gene expression of these samples are analyzed to determine transcriptional regulatory effects of LKB1 expression. Results of this analysis are compared to our analysis of resected human tumors to determine gene patterns that are differentially expressed between LKB1-deficient and LKB1-wild-type tumors whose expression is also affected by restoration of LKB1 in vitro. RMA gene expression was taken from two cell lines stably expressing LKB1 or controls of K78I mutant LKB1 or empty pBABE vector. Log2 average expression differences are calculated and compared to results from analysis of gene expression associated with LKB1 loss in resected human tumors.
Project description:Background: 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 aggressive cancer state that stems from Lkb1 deficiency can be reverted remains unknown.Purpose: To assess the acute transcriptional response to Lkb1 restoration within established lung tumors in a genetically engineered mouse model of oncogenic KRAS-driven lung adenocarcinoma. Approach: To control LKB1 function in vivo, we generated an Lkb1XTR allele, which enables Cre-mediated disruption of Lkb1 expression during tumor development and subsequent FLPo-ERT2-mediated reactivation of Lkb1 within established tumors. Lung tumors were initiated in KrasLSL-G12D/+;R26LSL-tdTomato (KT; Lkb1 wild-type), KT;Lkb1XTR/XTR (non-restorable), and KT;Lkb1XTR/XTR;FLPo-ERT2 (restorable) mice with Lenti-Cre. Prior isolating neoplastic cells by FACS for gene expression profiling by RNA-seq, lung tumor-bearing were treated with either corn oil vehicle or tamoxifen for two weeks following tumor development. Results: Lkb1 restoration resulted in higher expression of markers of alveolar type II epithelial cells as well as gene sets relating to immunomodulation and lipid metabolism export, which are important functions of mature alveolar type II epithelial cells. Conclusions: LKB1 promotes the expression of C/EBP target genes and consequently drives features of alveolar type II epithelial cell differentiation.
Project description:Background: LKB1 is among the most frequently altered tumor suppressors in lung adenocarcinoma. Despite being implicated in the regulation of a variety of cellular processes, the mechanisms by which LKB1 constrains lung tumor growth and progression remains an area of intense investigation. Purpose: To determine the extent of overlap in terms of the transcriptomic states arising from either Lkb1 deletion or Sik-targeting within cancer cells isolated from genetically engineered mouse models of oncogenic Kras-driven lung adenocarcinoma Approach: Cancer cells sorted from mouse lung tumors of defined genotypes were profiled by RNA-seq. Results: A strong overlap existed between Lkb1-deficient and Sik-targeted cancer cells both at the gene and pathways levels. Conclusions: Given the strong transcriptional overlap, loss of either Lkb1 or Sik appear to be functionally related.
Project description:Background: 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 aggressive cancer state that stems from Lkb1 deficiency can be reverted remains unknown. Restoration of Lkb1 in established lung tumors promotes the expression of C/EBP target genes as well as features of alveolar type II cell differentiation, which requires the activity of C/EBP transcription factors in the developmental setting. Purpose: To determine the extent to which the disruption of C/EBP transcription factors recapitulates the transcriptional changes induced by the inactivation of Lkb1.Approach: To assess the changes gene expression induced by CRISPR/Cas9-mediated disruption of either C/EBP transcription factors or Lkb1, we induced lung tumors in KrasLSL-G12D/+;R26LSL-tdTomato;H11LSL-Cas9 mice using Lenti-sgNeo1/sgNT/sgNeo2/Cre (sgInert), Lenti-sgLkb1/Cre (sgLkb1), or Lenti-sgCebpa/sgCebpb/sgCebpd/Cre (sgCebpa/b/d). Neoplastic cells were then isolated from lung tumors by FACS for gene expression profiling by RNA-seq. Results: The disruption of C/EBP transcription factors partially recapitulates the gene expression changes induced by Lkb1 inactivation. Among the genes that are jointly dependent upon C/EBP transcription factors and LKB1 is an enrichment of NKX2-1-dependent target genes. Conclusions: C/EBP transcription factors likely operate downstream of LKB1 in an indirect manner, collaborating with another key developmental regulator, NKX2-1, to enforce alveolar type II cell differentiation to constrain tumor growth.