Dataset Information

Molecular Portrait of Hypoxia in Breast Cancer: A Prognostic Signature and Novel HIF-Regulated Genes.

ABSTRACT: Intratumoral hypoxia has been associated with invasion, metastasis, and treatment failure, prompting the need for a global characterization of the response to hypoxic conditions. The current study presents the results of a large-scale RNA sequencing (RNA-seq) effort, analyzing 31 breast cancer cell lines representative of breast cancer subtypes or normal mammary epithelial (NME) cells exposed to control tissue culture conditions (20% O2) or hypoxic conditions (1% O2). The results demonstrate that NME have a stronger response to hypoxia both in terms of number of genes induced by hypoxia as well as level of expression. A conserved 42-gene hypoxia signature shared across PAM50 subtypes and genes that are exclusively upregulated in Luminal A, Luminal B, and normal-like mammary epithelial cells is identified. The 42-gene expression signature is enriched in a subset of basal-like cell lines and tumors and differentiates survival among patients with basal-like tumors. Mechanistically, the hypoxia-inducible factors (HIF-1 and/or HIF-2) mediate the conserved hypoxic response. Also, four novel hypoxia-regulated and HIF-1-responsive genes were identified as part of the conserved signature. This dataset provides a novel resource to query transcriptional changes that occur in response to hypoxia and serves as a starting point for a clinical assay to aid in stratifying patients that would benefit from hypoxia-targeted therapies, some of which are currently in clinical trials. IMPLICATIONS: RNA-seq of 31 breast cancer cells exposed to control or hypoxic conditions reveals a conserved genomic signature that contains novel HIF-regulated genes and is prognostic for the survival of patients with triple-negative breast cancer.

SUBMITTER: Ye IC

PROVIDER: S-EPMC6279594 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

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Molecular Portrait of Hypoxia in Breast Cancer: A Prognostic Signature and Novel HIF-Regulated Genes.

Ye I Chae IC Fertig Elana J EJ DiGiacomo Josh W JW Considine Michael M Godet Inês I Gilkes Daniele M DM

Molecular cancer research : MCR 20180723 12

Intratumoral hypoxia has been associated with invasion, metastasis, and treatment failure, prompting the need for a global characterization of the response to hypoxic conditions. The current study presents the results of a large-scale RNA sequencing (RNA-seq) effort, analyzing 31 breast cancer cell lines representative of breast cancer subtypes or normal mammary epithelial (NME) cells exposed to control tissue culture conditions (20% O<sub>2</sub>) or hypoxic conditions (1% O<sub>2</sub>). The r ...[more]

PMID: 30037853

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Project description:BACKGROUND: Hypoxia-inducible factor 1 (HIF-1) is a master transcriptional regulator of genes regulating oxygen homeostasis. The HIF-1 protein is composed of two HIF-1alpha and HIF-1beta/aryl hydrocarbon receptor nuclear translocator (ARNT) subunits. The prognostic relevance of HIF-1alpha protein overexpression has been shown in breast cancer. The impact of HIF-1alpha alternative splice variant expression on breast cancer prognosis in terms of metastasis risk is not well known. METHODS: Using real-time quantitative reverse transcription PCR assays, we measured mRNA concentrations of total HIF-1alpha and 4 variants in breast tissue specimens in a series of 29 normal tissues or benign lesions (normal/benign) and 53 primary carcinomas. In breast cancers HIF-1alpha splice variant levels were compared to clinicopathological parameters including tumour microvessel density and metastasis-free survival. RESULTS: HIF-1alpha isoforms containing a three base pairs TAG insertion between exon 1 and exon 2 (designated HIF-1alphaTAG) and HIF-1alpha736 mRNAs were found expressed at higher levels in oestrogen receptor (OR)-negative carcinomas compared to normal/benign tissues (P = 0.009 and P = 0.004 respectively). In breast carcinoma specimens, lymph node status was significantly associated with HIF-1alphaTAG mRNA levels (P = 0.037). Significant statistical association was found between tumour grade and HIF-1alphaTAG (P = 0.048), and total HIF-1alpha (P = 0.048) mRNA levels. HIF-1alphaTAG mRNA levels were also inversely correlated with both oestrogen and progesterone receptor status (P = 0.005 and P = 0.033 respectively). Univariate analysis showed that high HIF-1alphaTAG mRNA levels correlated with shortened metastasis free survival (P = 0.01). CONCLUSIONS: Our results show for the first time that mRNA expression of a HIF-1alphaTAG splice variant reflects a stage of breast cancer progression and is associated with a worse prognosis.See commentary: http://www.biomedcentral.com/1741-7015/8/45.

Project description:BackgroundHypoxia, which affects the development, metastasis and prognosis of cancer, represents a key feature of cancer. This study describe a hypoxia risk factor model, with predicting the prognosis of cervical cancer.MethodsBased on hypoxia pathway related genes, we divided cervical cancer samples into high and low expression groups. A cox analysis was then performed. Genes from these cervical cancer samples showing a significant impact on OS were selected for cluster analysis to obtain two subtypes. The TPM dataset of TCGA was divided into training and validation sets. For the training set, a lasso analysis was conducted as based on cox analysis of meaningful genes and a risk factor model was constructed. The constructed model was verified in internal and external data sets. Finally, RT-PCR, immunohistochemistry were used to detect the expression of relative genes or proteins and functional assays were used to evaluate the biological function of signature genes.ResultsTwo molecular subtypes were obtained, Cluster2 vs Cluster1.These subtypes were obtained by clustering with a total of 149 DEGs (Differential expressed genes) being in line with this standard, of which 27 were up-regulated and 122 were down-regulated. The five genes with lambda = 0.0571 were selected to construct the model, the RiskScore = AK4*0.042 + HK2*0.021 + P4HA1*0.22 + TGFBI*0.1 + VEGFA*0.077. Further, in order to verify the signature, we used TCGA-test and GSE44001 chip datasets to test, and finally got a good risk prediction effect in those datasets. Moreover, the result of RT-PCR and immunohistochemistry demonstrated that AK4, HK2, P4HA1, TGFBI and VEGFA were all highly expressed in these cervical cancer tissue samples. The functional study shown that expression of AK4, HK2, P4HA1, TGFBI and VEGFA can regulate the proliferation, migration, and invasion ability of cervical cancer cells in vitro.ConclusionsIn summary, we developed a 5-gene signature prognostic hierarchical system based on the hypoxic pathway of cervical cancer, which is independent of clinical characteristics. And also conducted experimental verifications on these signature gene. Therefore, we propose that use of this classifier as a molecular diagnostic test can provide an effective means for evaluating the prognostic risk of cervical cancer patients, and provide potential targets for the treatment of cervical cancer patients.

Dataset Information

Molecular Portrait of Hypoxia in Breast Cancer: A Prognostic Signature and Novel HIF-Regulated Genes.

Publications

Molecular Portrait of Hypoxia in Breast Cancer: A Prognostic Signature and Novel HIF-Regulated Genes.

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