Dataset Information

Ect2-Dependent rRNA Synthesis Is Required for KRAS-TRP53-Driven Lung Adenocarcinoma.

ABSTRACT: The guanine nucleotide exchange factor (GEF) epithelial cell transforming sequence 2 (Ect2) has been implicated in cancer. However, it is not clear how Ect2 causes transformation and whether Ect2 is necessary for tumorigenesis in vivo. Here, we demonstrate that nuclear Ect2 GEF activity is required for Kras-Trp53 lung tumorigenesis in vivo and that Ect2-mediated transformation requires Ect2-dependent rDNA transcription. Ect2 activates rRNA synthesis by binding the nucleolar transcription factor upstream binding factor 1 (UBF1) on rDNA promoters and recruiting Rac1 and its downstream effector nucleophosmin (NPM) to rDNA. Protein kinase C? (PKC?)-mediated Ect2 phosphorylation stimulates Ect2-dependent rDNA transcription. Thus, Ect2 regulates rRNA synthesis through a PKC?-Ect2-Rac1-NPM signaling axis that is required for lung tumorigenesis.

SUBMITTER: Justilien V

PROVIDER: S-EPMC5310966 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Ect2-Dependent rRNA Synthesis Is Required for KRAS-TRP53-Driven Lung Adenocarcinoma.

Justilien Verline V Ali Syed A SA Jamieson Lee L Yin Ning N Cox Adrienne D AD Der Channing J CJ Murray Nicole R NR Fields Alan P AP

Cancer cell 20170119 2

The guanine nucleotide exchange factor (GEF) epithelial cell transforming sequence 2 (Ect2) has been implicated in cancer. However, it is not clear how Ect2 causes transformation and whether Ect2 is necessary for tumorigenesis in vivo. Here, we demonstrate that nuclear Ect2 GEF activity is required for Kras-Trp53 lung tumorigenesis in vivo and that Ect2-mediated transformation requires Ect2-dependent rDNA transcription. Ect2 activates rRNA synthesis by binding the nucleolar transcription factor ...[more]

PMID: 28110998

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Project description:Non-small-cell lung cancer, histologically classified into adenocarcinoma (AD) and squamous cell carcinoma, is one of the most deadly malignancies worldwide. Lung AD (LUAD) could benefit of a plethora of target therapies and, in the last few years, also of immunotherapies. Here we focused on a real-life cohort of LUAD and The Cancer Genome Atlas (TCGA)-LUAD dataset aiming to gain insights into the immune contexture of such a malignancy. We explored the mutational status of 41 genes and the expression of 94 genes, related to immune-checkpoint, inflammation, and stromal microenvironment. Surprisingly, we found that our cohort has a very low mutational burden if we consider our panel as its surrogate. Regarding gene expression data, we identified 31 genes significantly deregulated in tumor tissues compared with a pool of normal samples. Unsupervised hierarchical clustering of the deregulated genes is able to identify two clusters of tumor samples, differently enriched in alterations in actionable genes. In particular, we identified a cluster enriched in patients carrying KRAS alterations. In silico deconvolution, that is the inferring of tumor microenvironment composition by gene expression data, through TIMER algorithm has been performed to explore immune microenvironment. Estimation performed on our gene expression matrix showed that B cell infiltration is lower in the KRAS-mutated enriched cluster, as in the TCGA-LUAD dataset. Such a finding has been validated in situ through immunohistochemistry in an independent cohort. Moreover, cases in LUAD-TCGA with low B cell infiltration have a significantly worse overall survival than those with higher levels. In the real-life cohort we observed that cases belonging to cluster enriched in KRAS-mutated patients have a poor outcome. LUAD driven by KRAS mutation represents an unmet clinical need, being refractory to pharmacological inhibition. Our results link KRAS mutations to B cell infiltration. Thus, the present findings could be helpful in a better definition of immunotherapeutic approaches for KRAS mutated patients.

Dataset Information

Ect2-Dependent rRNA Synthesis Is Required for KRAS-TRP53-Driven Lung Adenocarcinoma.

Publications

Ect2-Dependent rRNA Synthesis Is Required for KRAS-TRP53-Driven Lung Adenocarcinoma.

Similar Datasets

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