Dataset Information

HER2/neu Immunostaining in Invasive Breast Cancer: Analysis of False Positive Factors.

ABSTRACT: OBJECTIVES: HER2/neu gene amplification by Fluorescent in situ hybridization and protein expression by immunohistochemistry have been used for prognosis and guidance for the treatment of invasive ductal carcinoma of the breast with Trastuzumab. False positive results are a significant problem where immunohistochemistry is exclusively used to test HER2/neu protein over expression. A minority of cases of breast cancer scoring HER2 (3+) by immunohistochemistry using Hercep test may not be associated with amplification of the HER2/neu gene by FISH, a test which is a more specific and sensitive than immunohistochemistry. This study aims to examine the factors contributing to false positive results by immunohistochemistry and subsequently not showing HER2/neu gene amplification by FISH analysis. METHODS: A retrospective analysis of 18 cases (3+) by immunohistochemistry in the pathology laboratory not associated with HER2/neu gene amplification was performed. The histological review of these cases was done, the technical error (i.e staining of blood vessels or benign ducts) and the interpretation errors were evaluated. RESULTS: Polysomy 17 was absent in all the cases studied by FISH analysis. By immunohistochemistry, five of the 18 cases were purely interpretation errors and the remaining were a combination of technical and interpretational errors. CONCLUSION: False positive results related to technical and interpretational errors can be prevented by properly educating the technologist and pathologist to perform high quality immunostains and to render an accurate diagnosis respectively. This issue is of utmost importance as it may have deleterious effects on the selection of therapeutic arsenal in invasive ductal carcinoma of the breast.

SUBMITTER: Arafah M

PROVIDER: S-EPMC3191663 | biostudies-other | 2010 Oct

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:BackgroundHER2/neu-positive breast cancer cells have recently been shown to use a unique Warburg-like metabolism for survival and aggressive behavior. These cells exhibit increased fatty acid synthesis and storage compared to normal breast cells or other tumor cells. Disruption of this synthetic process results in apoptosis. Since the addition of physiological doses of exogenous palmitate induces cell death in HER2/neu-positive breast cancer cells, the pathway is likely operating at its limits in these cells. We have studied the response of HER2/neu-positive breast cancer cells to physiological concentrations of exogenous palmitate to identify lipotoxicity-associated consequences of this physiology. Since epidemiological data show that a diet rich in saturated fatty acids is negatively associated with the development of HER2/neu-positive cancer, this cellular physiology may be relevant to the etiology and treatment of the disease. We sought to identify signaling pathways that are regulated by physiological concentrations of exogenous palmitate specifically in HER2/neu-positive breast cancer cells and gain insights into the molecular mechanism and its relevance to disease prevention and treatment.MethodsTranscriptional profiling was performed to assess programs that are regulated in HER2-normal MCF7 and HER2/neu-positive SKBR3 breast cancer cells in response to exogenous palmitate. Computational analyses were used to define and predict functional relationships and identify networks that are differentially regulated in the two cell lines. These predictions were tested using reporter assays, fluorescence-based high content microscopy, flow cytometry and immunoblotting. Physiological effects were confirmed in HER2/neu-positive BT474 and HCC1569 breast cancer cell lines.ResultsExogenous palmitate induces functionally distinct transcriptional programs in HER2/neu-positive breast cancer cells. In the lipogenic HER2/neu-positive SKBR3 cell line, palmitate induces a G2 phase cell cycle delay and CHOP-dependent apoptosis as well as a partial activation of the ER stress response network via XBP1 and ATF6. This response appears to be a general feature of HER2/neu-positive breast cancer cells but not cells that overexpress only HER2/neu. Exogenous palmitate reduces HER2 and HER3 protein levels without changes in phosphorylation and sensitizes HER2/neu-positive breast cancer cells to treatment with the HER2-targeted therapy trastuzumab.ConclusionsSeveral studies have shown that HER2, FASN and fatty acid synthesis are functionally linked. Exogenous palmitate exerts its toxic effects in part through inducing ER stress, reducing HER2 expression and thereby sensitizing cells to trastuzumab. These data provide further evidence that HER2 signaling and fatty acid metabolism are highly integrated processes that may be important for disease development and progression.

Project description:Overexpression of the oncogene HER2/neu (c-erbB-2) occurs in up to 30% of breast cancers and is correlated with reduced survival, especially in node-positive disease. The aim of this study was to identify genes associated with the aggressive phenotype of HER2/neu-positive breast cancer cells using cDNA microarrays. RNA was extracted from three HER2/neu-positive and three HER2/neu-negative breast cancer cell lines. Pooled RNA was hybridized in duplicate to the breast specific microarray filters from Research Genetics containing 5184 unique cDNAs. Subsequently, a similar comparison was performed for pooled RNAs from 10 node-positive, ER-positive invasive ductal carcinomas, half of which were HER2/neu overexpressers. In HER2/neu overexpressing breast cancer cell lines, 90 (1.7%) genes were up-regulated and 46 (0.9%) were down-regulated, compared to cell lines with low HER2/neu protein levels. In contrast, in HER2/neu overexpressing primary breast cancers, more genes were down-regulated (N = 132, 2.5%) than up-regulated (N = 19, 0.4%). Many of the differentially expressed genes have previously not been known to play a role in human neoplasia, and some of them may represent novel tumor suppressor or oncogenes. No genes were up-regulated, and only a small number of genes were down-regulated both in cell lines and in carcinomas with high HER2/neu protein levels. These included transforming acidic coiled-coil containing protein 1, glycogen phosphorylase BB, complement 1q and one EST. The differential expression of select genes was confirmed by Northern blotting (trefoil factor 3) or by immunocytochemistry (glycogen phosphorylase BB, vimentin, KAI1). In an extended validation study, 18 of 41 ER-negative, but none of 46 ER-positive, breast carcinomas were found to express vimentin, and all but one of the vimentin-positive tumors were confined to the HER2/neu-negative subgroup (P = 0.0019). Our findings support an important role of the mammary stroma in determining the clinical breast cancer phenotype.

Dataset Information

HER2/neu Immunostaining in Invasive Breast Cancer: Analysis of False Positive Factors.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets