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Gene expression analysis of metastatic adrenocortical tumors

ABSTRACT: Background: Adrenocortical carcinoma (ACC) is a rare, often-aggressive neoplasm of the adrenal cortex, with a 14.5-month median overall survival. We asked whether tumors from patients with advanced or metastatic ACC would offer clues as to putative genes that might have critical roles in disease progression or in more aggressive disease biology. Methods: We conducted comprehensive genomic and expression analyses of 43 ACCs. Results: Copy number gains and losses matched that previously reported. We identified a median mutation rate of 3.38 per megabase (Mb), somewhat higher than in a previous study possibly related to the more advanced disease. The mutational signature was characterized by a predominance of C>T, C>A and T>C transitions. As in previously reports, only cancer genes TP53 (26%) and beta-catenin (CTNNB1, 14%) were mutated in more than 10% of samples. The TCGA-identified putative cancer genes MEN1 and PRKAR1A were found in low frequency – 4.7% and 2.3%, respectively. Most of the mutations were in genes not implicated in the etiology or maintenance of cancer. Specifically, amongst the 38 genes that were mutated in more than 9% of samples, only four were represented in Tier 1 of the 576 COSMIC Cancer Gene Census (CCGC). Thus, 82% of genes found to have mutations likely have no role in the etiology or biology of ACC; while the role of the other 18%, if any, remains to be proven. Finally, the transcript length for the 38 most frequently mutated genes in ACC is statistically longer than the average of all coding genes, raising the question of whether transcript length in part determined mutation probability. Conclusions: We conclude that the mutational and expression profiles of advanced and metastatic tumors is very similar to those from newly diagnosed patients –with very little in the way of genomic aberration to explain it. Our data and that in the previous analyses finds the rate of mutations in ACCs lower than that in other cancers and suggests an epigenetic basis for the disease should be the focus of future studies. The Affymetrix PrimeView platform was used for the gene expression profiling.

ORGANISM(S): Homo sapiens

PROVIDER: GSE143383 | GEO | 2020/09/25

REPOSITORIES: GEO

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Project description:Background: Adrenocortical carcinoma (ACC) is a rare, often-aggressive neoplasm of the adrenal cortex, with a 14.5-month median overall survival. We asked whether tumors from patients with advanced or metastatic ACC would offer clues as to putative genes that might have critical roles in disease progression or in more aggressive disease biology. Methods: We conducted comprehensive genomic and expression analyses, including microRNA profiling, of 33 ACCs and 6 normal adrenals. Results: Copy number gains and losses matched that previously reported. We identified a median mutation rate of 3.38 per megabase (Mb), somewhat higher than in a previous study possibly related to the more advanced disease. The mutational signature was characterized by a predominance of C>T, C>A and T>C transitions. As in previously reports, only cancer genes TP53 (26%) and beta-catenin (CTNNB1, 14%) were mutated in more than 10% of samples. The TCGA-identified putative cancer genes MEN1 and PRKAR1A were found in low frequency – 4.7% and 2.3%, respectively. Most of the mutations were in genes not implicated in the etiology or maintenance of cancer. Specifically, amongst the 38 genes that were mutated in more than 9% of samples, only four were represented in Tier 1 of the 576 COSMIC Cancer Gene Census (CCGC). Thus, 82% of genes found to have mutations likely have no role in the etiology or biology of ACC; while the role of the other 18%, if any, remains to be proven. Finally, the transcript length for the 38 most frequently mutated genes in ACC is statistically longer than the average of all coding genes, raising the question of whether transcript length in part determined mutation probability. Conclusions: We conclude that the mutational and expression profiles of advanced and metastatic tumors is very similar to those from newly diagnosed patients –with very little in the way of genomic aberration to explain it. Our data and that in the previous analyses finds the rate of mutations in ACCs lower than that in other cancers and suggests an epigenetic basis for the disease should be the focus of future studies. The Exiqon miRCURY LNA microRNA array v.11.0 platform was used for the microRNA profiling.

Project description:Adrenocortical carcinoma (ACC) is an aggressive malignancy with a low but variable overall survival rate. Even after complete tumor resection, over half of patients develop recurrent disease. Long noncoding RNAs (lncRNAs) have been found to be involved in cancer initiation/progression and as markers of cancer prognosis. The role of lncRNAs in ACC is poorly understood. Thus, in this study we performed lncRNA expression profiling in ACC, adrenocortical adenoma (ACA) and normal adrenal cortex (NAC). Total RNA was extracted from fresh frozen tissue samples (11 ACA, nine ACC and five NAC samples) with histopathological confirmed diagnosis. ArrayStar Human LncRNA/mRNA Expression Microarray V3.0 was used for transcriptome analysis. Differentially expressed lncRNAs were validated using TaqMan real-time quantitative PCR in a validation cohort including an additional 10 ACCs. The ACC dataset from the Cancer Genome Atlas (TCGA) project was used to evaluate the prognostic utility of lncRNAs found to be differentially expressed in ACC. Survival curves were plotted by Kaplan-Meier analysis, and differences in survival rates were assessed using a log-rank test. P < 0.05 was considered significant. Gene Set Enrichment Analysis (GSEA) was performed to identify lncRNA-associated biological signaling pathways. Unsupervised hierarchical and heat map clustering showed distinct clustering of ACC samples compared with NAC and ACA samples by lncRNA expression profiles. A total of 874 lncRNAs were differentially expressed between ACC and NAC, including known carcinogenesis-related lncRNAs such as HOTTIP, HOXA11-AS1, CRNDE, LINC00271 and TBXAS1. One thousand seventy-six lncRNAs were differentially expressed between ACC and ACA. LINC00271 was a prognostic marker, with patients with low LINC00271 expression surviving significantly shorter than patients with a high LINC00271 expression. Median survival time (MST) for the low-expression group was 1788 days, whereas the MST was not reached for the high-expression group (P < 0.019). Importantly, low LINC00271 expression was positively associated with WNT signaling, cell cycle, chromosome segregation and tissue morphogenesis pathways. ACC has a distinct lncRNA expression profile. LINC00271 is a prognostic marker in ACC and is involved in biological pathways commonly dysregulated in ACC.

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Gene expression analysis of metastatic adrenocortical tumors

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