Project description:CTNNB1 is the most frequently mutated gene in hepatocellular carcinoma (HCC). However, its clinical relevance remains controversial. We determined an evolutionarily conserved β-catenin signature by comparative analysis of gene expression data from human HCC (GSE43619) and a mouse model.
Project description:In rodent liver, a single injection of N-nitrosodiethylamine (DEN) followed by chronic treatment with the antiepileptic drug phenobarbital (PB) promotes the outgrowth of hepatocellular tumors with activating mutations in Ctnnb1, encoding the transcription factor β-catenin. We now studied long-term effects of PB treatment in livers of transgenic mice with hepatocyte-specific knockout (KO) of Apc, a negative regulator of β-catenin signaling. The number of Apc KO hepatocytes present in the liver decreased with age, indicative of a selective disadvantage of Apc KO cells in the absence of PB. Following liver tumor promotion by PB in Apc KO mice for 9 months, tumor burden was quantified and histological appearance, gene expression profiles, and activity of oncogenic signaling pathways of the tumors were analyzed. In Apc KO mice fed with PB, we observed an increased hepatic tumor volume fraction and tumor multiplicity, as compared to non-promoted animals. Tumors in the PB-treated Apc KO group were mostly eosinophilic hepatocellular adenoma with activated β-catenin, due to the deletion of Apc. These tumors exhibited striking phenotypic similarities to DEN-induced Ctnnb1-mutated tumors, regarding histological appearance and expression of marker proteins and mRNAs. A particular sub-population of tumors, Apc KO-driven basophilic hepatocellular carcinomas, exclusively appeared in the non-PB-treated group but was absent from PB-promoted livers. In conclusion, phenobarbital promotes the outgrowth of Apc-deficient, β-catenin-activated hepatocellular adenoma while simultaneously inhibiting the formation of a certain population of Apc-driven hepatocellular carcinoma.
Project description:Up to 41% of hepatocellular carcinomas (HCCs) result from activating mutations in the CTNNB1 gene encoding β-catenin. β-catenin has dual cellular functions as a component of the Wnt signaling pathway and adherens junctions. HCC-associated CTNNB1 mutations stabilize the β-catenin protein, leading to nuclear and/or cytoplasmic localization of β-catenin and downstream activation of Wnt target genes. In patient HCC samples, β-catenin nuclear and cytoplasmic localization are typically patchy, even among HCC with highly active CTNNB1 mutations. The functional and clinical relevance of this heterogeneity in β-catenin activation are not well understood. To define mechanisms of β-catenin-driven HCC initiation, we generated a Cre-lox system that enabled switching on activated β-catenin in 1) a small number of hepatocytes in early development; or 2) the majority of hepatocytes in later development or adulthood. We discovered that switching on activated β-catenin in a subset of larval hepatocytes was sufficient to drive HCC initiation. To determine the role of Wnt/β-catenin signaling heterogeneity later in hepatocarcinogenesis, we performed RNA-seq analysis of zebrafish β-catenin-driven HCC. Ingenuity Pathway Analysis of differentially expressed genes in the Cre-lox HCC model revealed that “Cancer” and “Liver Tumor” categories were significantly altered, indicating transcriptional similarities with human HCC and other vertebrate HCC models. At the single-cell level, 2.9% to 15.2% of hepatocytes from zebrafish β-catenin-driven HCC expressed two or more of the Wnt target genes axin2, mtor, glula, myca, and wif1, indicating focal activation of Wnt signaling in established tumors. Thus, heterogeneous β-catenin activation drives HCC initiation and persists throughout hepatocarcinogenesis.
Project description:Up to 41% of hepatocellular carcinomas (HCCs) result from activating mutations in the CTNNB1 gene encoding β-catenin. β-catenin has dual cellular functions as a component of the Wnt signaling pathway and adherens junctions. HCC-associated CTNNB1 mutations stabilize the β-catenin protein, leading to nuclear and/or cytoplasmic localization of β-catenin and downstream activation of Wnt target genes. In patient HCC samples, β-catenin nuclear and cytoplasmic localization are typically patchy, even among HCC with highly active CTNNB1 mutations. The functional and clinical relevance of this heterogeneity in β-catenin activation are not well understood. To define mechanisms of β-catenin-driven HCC initiation, we generated a Cre-lox system that enabled switching on activated β-catenin in 1) a small number of hepatocytes in early development; or 2) the majority of hepatocytes in later development or adulthood. We discovered that switching on activated β-catenin in a subset of larval hepatocytes was sufficient to drive HCC initiation. To determine the role of Wnt/β-catenin signaling heterogeneity later in hepatocarcinogenesis, we performed RNA-seq analysis of zebrafish β-catenin-driven HCC. Ingenuity Pathway Analysis of differentially expressed genes in the Cre-lox HCC model revealed that “Cancer” and “Liver Tumor” categories were significantly altered, indicating transcriptional similarities with human HCC and other vertebrate HCC models. At the single-cell level, 2.9% to 15.2% of hepatocytes from zebrafish β-catenin-driven HCC expressed two or more of the Wnt target genes axin2, mtor, glula, myca, and wif1, indicating focal activation of Wnt signaling in established tumors. Thus, heterogeneous β-catenin activation drives HCC initiation and persists throughout hepatocarcinogenesis.
Project description:Aberrant activation of Wnt/β-catenin signaling is observed in numerous cancers. In hepatocellular carcinoma activating mutations in CTNNB1 (20-25%) or loss of function mutations in AXIN1 (10%), AXIN2 (2%) and APC (1-2%) are observed. All these mutations lead to aberrant stabilization of β-catenin, which constitutively activates downstream Wnt/β-catenin target genes and triggers a genetic program resulting in tumor formation. However, in relation to AXIN1 mutations some reports have challenged whether these indeed result in tumor growth by enhancing β-catenin signaling (e.g. PMID: 16964294, 29525529). Several alternative pathways have also been linked to AXIN1 (ENSG00000103126), such as TGFβ, SAPK/JNK, p53, YAP/TAZ and c-myc. To identify which one of these or other unknown signaling routes are linked to AXIN1, using CRISPR-Cas9 genome editing, we have successfully repaired the homozygous p.R712* AXIN1 mutation present in the SNU449 hepatocellular carcinoma cell line. Next, using RNA sequencing the RNA expression patterns of 3 independent repaired clones were compared with 3 clones retaining the AXIN1 mutation. Surprisingly, only 5 genes were significantly altered in the repaired clones, among which AXIN2, a well-established β-catenin target gene. Thus, this analysis leads to the surprising observation that a commonly observed mutation in a hepatocellular tumor suppressor gene, is associated with minimal alterations in gene expression, at least in the SNU449 cell line.
Project description:CTNNB1 is the most frequently mutated gene in hepatocellular carcinoma (HCC). However, its clinical relevance remains controversial. We determined an evolutionarily conserved β-catenin signature by comparative analysis of gene expression data from human HCC and a mouse model (GSE43628). We generated gene expression data from the tumors of 88 HCC patients who underwent surgical resection as the primary treatment. We used these gene expression data to develop a new prognostification model for prognosis of HCC after surgery. We generated gene expression data from the tumors of 88 HCC patients who underwent surgical resection as the primary treatment.
Project description:CTNNB1 is the most frequently mutated gene in hepatocellular carcinoma (HCC). However, its clinical relevance remains controversial. We determined an evolutionarily conserved β-catenin signature by comparative analysis of gene expression data from human HCC and a mouse model (GSE43628). We generated gene expression data from the tumors of 88 HCC patients who underwent surgical resection as the primary treatment. We used these gene expression data to develop a new prognostification model for prognosis of HCC after surgery.
Project description:The Wnt signaling pathway is involved in many differentiation events during embryonic development and can lead to tumor formation after aberrant activation of its components. Β-catenin, a cytoplasmic component, plays a major role in the transduction of the canonical wnt/ β-catenin signaling. The aim of this study was to identify novel genes that are regulated by active β-catenin/TCF signaling in hepatocellular carcinoma. We selected and expanded isogenic clones from hepatocellular carcinoma-derived Huh7 cells with high and low β-catenin/TCF activities. We showed that, high TCF activity Huh7 cells lead to bigger and more aggressive tumors when xenografted into nude mice. We used SAGE (Serial Analysis of Gene Expression), genome-wide microarray and in silico promoter analysis in parallel, to compare gene expression between low (basal) and high (transfected) β-catenin/TCF activity clones, those had been xenografted into nude mice. We compared and contrasted SAGE and genome-wide microarray data, in parallel. Finally; after combined analysis, we identified BRI3 and HSF2 as novel targets of Wnt/β-catenin signaling in hepatocellular carcinoma. Experiment Overall Design: High TCF activity Huh7 cell line (Huh7-S33Y) was compared to control Huh7 cell line (Huh7-Vec) by using 10 ug of total RNA isolated from each sample (15 ug of labeled cRNA was hybridized to the arrays). Triplicates are coming from same total RNA extraction.
Project description:Stable activation of the WNT signaling effector beta-catenin (CTNNB1(ex3) in ovarian granulosa cells results in the formation of premalignant lesions that develop into granulosa cell tumors (GCTs) spontaneously later in life. Loss of the tumor suppressor gene Pten accelerates GCT formation in the CTNNB1 strain. Conversely, expression of oncogenic KRASG12D causes the dramatic arrest of proliferation, differentiation and apoptosis in granulosa cells, and consequently, small abnormal follicle-like structures devoid of oocytes accumulate in the ovary. Because of the potent anti-proliferative effects of KRASG12D in granulosa cells, we sought to determine if KRASG12D would block precancerous lesion and tumor formation in follicles of the CTNNB1 mutant mice. Unexpectedly, transgenic Ctnnb1;Kras mutant mice developed early-onset GCTs leading to premature death in a manner similar to theCtnnb1;Pten mutant mice. Moreover, the GCTs in the Ctnnb1;Kras mutant mice exhibited increased GC proliferation, decreased apoptosis and impaired differentiation. Microarray and RT-PCR analyses revealed that ovaries from mice expressing dominant-stable CTNNB1 with either Pten loss or KRAS activation were unpredictably similar. Specifically, gene regulatory processes induced by CTNNB1 were mostly enhanced by either KRAS activation or Pten loss in remarkably similar patterns and degree. Furthermore, the concomitant activation of CTNNB1 and KRAS in Sertoli cells resulted in the development of granulosa cell tumors of the testis. RT-PCR studies showed a partial overlap in gene regulatory processes associated with tumor development in the ovary and testis. Together, these results suggest that KRAS activation and Pten loss induce GCT development from premalignant lesions via highly similar molecular mechanisms. four samples: average of two wild type samples (previously submitted as GSM403220 and GSM403221), beta-Catenin constitutively active mutant, beta-Catenin;Pten double mutant, and beta-Catenin;Kras(G12D) double mutant