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Transcription profiling of human breast tumors to identify age-specific differences of oncogenic pathway deregulation

ABSTRACT: Breast cancer arising in young women has a poorer prognosis, is less likely to be hormone sensitive, and represents a particularly challenging clinical entity. The biology driving the aggressive nature of breast cancer arising in young women has yet to be defined. Among 784 patients with early stage breast cancer, using prospectively-defined, age-specific cohorts (young <= 45 years; older >= 65 years), 411 eligible patients (n = 200 < 45 years; n = 211 >= 65 years) with clinically-annotated Affymetrix microarray data were identified. Gene set enrichment analyses, signatures of oncogenic pathway deregulation and predictors of chemotherapy sensitivity were evaluated within the two age-defined cohorts. In comparing deregulation of oncogenic pathways between age groups, a statistically higher probability of PI3K (p = 0.006) and Myc (p = 0.03) pathway deregulation was observed in the tumors of younger women. When evaluating unique patterns of pathway deregulation, a low probability of Src and E2F deregulation in tumors of younger women, concurrent with activation of PI3K, Myc, and beta-catenin, conferred a worse prognosis (HR = 4.15; p = 0.008). In contrast, a higher probability of Src and E2F pathway activation in tumors of older women, concurrent low probability of PI3K, Myc and beta-catenin deregulation, was associated with a poorer outcome (HR = 2.7; p = 0.006). Similar pathway differences were identified using gene set enrichment analysis. Importantly, in multivariate analyses including clinico-pathologic variables, genomic clusters of pathway deregulation were identified to be independent predictors of disease-free survival. Finally, a significant relationship (p = 0.02) between anthracycline sensitivity and genomic clusters was observed among women aged >= 65 years. Submitters do not have approval to publish the .CEL files Experiment Overall Design: n=78

ORGANISM(S): Homo sapiens

SUBMITTER: Anders CK

PROVIDER: S-ECPF-GEOD-7849 | biostudies-other | 2008

REPOSITORIES: biostudies-other

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Project description:Malignant pleural mesothelioma (MPM) is a lethal neoplasm exhibiting resistance to most treatment regimens and requires effective therapeutic options. Though an effective strategy in many cancer, targeted therapy is relatively unexplored in MPM because the therapeutically important oncogenic pathways and networks in MPM are largely unknown.We carried out gene expression microarray profiling of 53 surgically resected MPMs tumors along with paired normal tissue. We also carried out whole transcriptomic sequence (RNA-seq) analysis on eight tumor specimens. Taqman-based quantitative Reverse-transcription polymerase chain reaction (qRT-PCR), western analysis and immunohistochemistry (IHC) analysis of mitotic arrest deficient-like 1 (MAD2L1) was carried out on tissue specimens. Cell viability assays of MPM cell lines were carried out to assess sensitivity to specific small molecule inhibitors.Bioinformatics analysis of the microarray data followed by pathway analysis revealed that the mitotic spindle assembly checkpoint (MSAC) pathway was most significantly altered in MPM tumors with upregulation of 18 component genes, including MAD2L1 gene. We validated the microarray data for MAD2L1 expression using quantitative qRT-PCR and western blot analysis on tissue lysates. Additionally, we analyzed expression of the MAD2L1 protein by IHC using an independent tissue microarray set of 80 MPM tissue samples. Robust clustering of gene expression data revealed three novel subgroups of tumors, with unique expression profiles, and showed differential expression of MSAC pathway genes. Network analysis of the microarray data showed the cytoskeleton/spindle microtubules network was the second-most significantly affected network. We also demonstrate that a nontaxane small molecule inhibitor, epothilone B, targeting the microtubules have great efficacy in decreasing viability of 14 MPM cell lines.Overall, our findings show that MPM tumors have significant deregulation of the MSAC pathway and the microtubule network, it can be classified into three novel molecular subgroups of potential therapeutic importance and epothilone B is a promising therapeutic agent for MPM.

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Transcription profiling of human breast tumors to identify age-specific differences of oncogenic pathway deregulation

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