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Frank Feleppa

Bio: Frank Feleppa is an academic researcher from Royal Melbourne Hospital. The author has contributed to research in topics: Bone marrow & Population. The author has an hindex of 7, co-authored 9 publications receiving 1578 citations.

Papers
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Journal ArticleDOI
TL;DR: It is found that breast tissue from BRCA1 mutation carriers harbors an expanded luminal progenitor population that shows factor-independent growth in vitro, and the findings suggest that an aberrant luminalprogenitor population is a target for transformation in BRCa1-associated basal tumors.
Abstract: Basal-like breast cancers arising in women carrying mutations in the BRCA1 gene, encoding the tumor suppressor protein BRCA1, are thought to develop from the mammary stem cell. To explore early cellular changes that occur in BRCA1 mutation carriers, we have prospectively isolated distinct epithelial subpopulations from normal mammary tissue and preneoplastic specimens from individuals heterozygous for a BRCA1 mutation. We describe three epithelial subsets including basal stem/progenitor, luminal progenitor and mature luminal cells. Unexpectedly, we found that breast tissue from BRCA1 mutation carriers harbors an expanded luminal progenitor population that shows factor-independent growth in vitro. Moreover, gene expression profiling revealed that breast tissue heterozygous for a BRCA1 mutation and basal breast tumors were more similar to normal luminal progenitor cells than any other subset, including the stem cell-enriched population. The c-KIT tyrosine kinase receptor (encoded by KIT) emerged as a key marker of luminal progenitor cells and was more highly expressed in BRCA1-associated preneoplastic tissue and tumors. Our findings suggest that an aberrant luminal progenitor population is a target for transformation in BRCA1-associated basal tumors .

1,339 citations

Journal ArticleDOI
TL;DR: In vivo evidence is provided that BH3 mimetics can be used to sensitize primary breast tumors to chemotherapy and further suggest that elevated BCL-2 expression constitutes a predictive response marker in breast cancer.
Abstract: Overexpression of the prosurvival protein BCL-2 is common in breast cancer. Here we have explored its role as a potential therapeutic target in this disease. BCL-2, its anti-apoptotic relatives MCL-1 and BCL-XL, and the proapoptotic BH3-only ligand BIM were found to be coexpressed at relatively high levels in a substantial proportion of heterogeneous breast tumors, including clinically aggressive basal-like cancers. To determine whether the BH3 mimetic ABT-737 that neutralizes BCL-2, BCL-XL, and BCL-W had potential efficacy in targeting BCL-2–expressing basal-like triple-negative tumors, we generated a panel of primary breast tumor xenografts in immunocompromised mice and treated recipients with either ABT-737, docetaxel, or a combination. Tumor response and overall survival were significantly improved by combination therapy, but only for tumor xenografts that expressed elevated levels of BCL-2. Treatment with ABT-737 alone was ineffective, suggesting that ABT-737 sensitizes the tumor cells to docetaxel. Combination therapy was accompanied by a marked increase in apoptosis and dissociation of BIM from BCL-2. Notably, BH3 mimetics also appeared effective in BCL-2–expressing xenograft lines that harbored p53 mutations. Our findings provide in vivo evidence that BH3 mimetics can be used to sensitize primary breast tumors to chemotherapy and further suggest that elevated BCL-2 expression constitutes a predictive response marker in breast cancer.

174 citations

Journal ArticleDOI
TL;DR: Compared to other methods, CD138 trephine immunohistology consistently demonstrated greater plasma-cell infiltration as well as more accurate quantification of plasma cells in bone marrow samples.
Abstract: Accurate quantification of plasma cells in bone marrow samples is essential for the diagnosis, classification and prognosis of plasma-cell dyscrasias. Published comparisons between aspirate/trephine morphology, flow cytometry and immunohistochemistry are lacking. Bone marrow plasma cells from 100 patients with plasma cell myeloma or monoclonal gammopathy of undetermined significance were quantified by a 500-cell differential count on Romanowsky-stained aspirate slides, flow-cytometry gating of CD38bright+/CD138+ cells, hematoxylin and eosin trephine section examination and CD138 trephine immunohistology. The results of quantification by the different methods were compared. Compared to other methods, CD138 trephine immunohistology consistently demonstrated greater plasma-cell infiltration. Immunohistology is the most sensitive method for assessment of plasma-cell infiltration at diagnosis or post-therapy, especially in patients with minimal bone marrow involvement.

67 citations

Journal ArticleDOI
TL;DR: It is hypothesized that expression of mutated IDH1 may play a role in the pathogenesis of TAE in low grade gliomas.
Abstract: Summary Objective The isocitrate dehydrogenase 1 (IDH1) R132H mutation is the most common mutation in World Health Organization (WHO) grade II gliomas, reported to be expressed in 70–80%, but only 5–10% of high grade gliomas. Low grade tumors, especially the protoplasmic subtype, have the highest incidence of tumor associated epilepsy (TAE). The IDH1 mutation leads to the accumulation of 2-hydroxyglutarate (2HG), a metabolite that bears a close structural similarity to glutamate, an excitatory neurotransmitter that has been implicated in the pathogenesis of TAE. We hypothesized that expression of mutated IDH1 may play a role in the pathogenesis of TAE in low grade gliomas. Methods Thirty consecutive patients with WHO grade II gliomas were analyzed for the presence of the IDH1-R132H mutation using immunohistochemistry. The expression of IDH1 mutation was semiquantified using open-source biologic-imaging analysis software. Results The percentage of cells positive for the IDH1-R132H mutation was found to be higher in patients with TAE compared to those without TAE (median and interquartile range (IQR) 25.3% [8.6–53.5] vs. 5.2% [0.6–13.4], p = 0.03). In addition, we found a significantly higher median IDH1 mutation expression level in the protoplasmic subtype of low grade glioma (52.2% [IQR 19.9–58.6] vs. 13.8% [IQR 3.9–29.4], p = 0.04). Significance Increased expression of the IDH1-R132H mutation is associated with seizures in low grade gliomas and also with the protoplasmic subtype. This supports the hypothesis that this mutation may play a role in the pathogenesis of both TAE and low grade gliomas.

60 citations

Journal ArticleDOI
TL;DR: A study comparing cerbB2 (neu or Her2) expression as assessed immunohistochemically in breast neoplasia using a panel of 6 commercially available antibodies determined the practical utility of each antibody, assessing ease of use, specific and non-specific staining characteristics, and expense, thus allowing a specific recommendation as to antibody of choice.

51 citations


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TL;DR: The philosophy and design of the limma package is reviewed, summarizing both new and historical features, with an emphasis on recent enhancements and features that have not been previously described.
Abstract: limma is an R/Bioconductor software package that provides an integrated solution for analysing data from gene expression experiments. It contains rich features for handling complex experimental designs and for information borrowing to overcome the problem of small sample sizes. Over the past decade, limma has been a popular choice for gene discovery through differential expression analyses of microarray and high-throughput PCR data. The package contains particularly strong facilities for reading, normalizing and exploring such data. Recently, the capabilities of limma have been significantly expanded in two important directions. First, the package can now perform both differential expression and differential splicing analyses of RNA sequencing (RNA-seq) data. All the downstream analysis tools previously restricted to microarray data are now available for RNA-seq as well. These capabilities allow users to analyse both RNA-seq and microarray data with very similar pipelines. Second, the package is now able to go past the traditional gene-wise expression analyses in a variety of ways, analysing expression profiles in terms of co-regulated sets of genes or in terms of higher-order expression signatures. This provides enhanced possibilities for biological interpretation of gene expression differences. This article reviews the philosophy and design of the limma package, summarizing both new and historical features, with an emphasis on recent enhancements and features that have not been previously described.

22,147 citations

Journal ArticleDOI
25 Mar 2011-Science
TL;DR: It is suggested that metastasis can be portrayed as a two-phase process: the first phase involves the physical translocation of a cancer cell to a distant organ, whereas the second encompasses the ability of the cancer cellto develop into a metastatic lesion at that distant site.
Abstract: Metastasis causes most cancer deaths, yet this process remains one of the most enigmatic aspects of the disease. Building on new mechanistic insights emerging from recent research, we offer our perspective on the metastatic process and reflect on possible paths of future exploration. We suggest that metastasis can be portrayed as a two-phase process: The first phase involves the physical translocation of a cancer cell to a distant organ, whereas the second encompasses the ability of the cancer cell to develop into a metastatic lesion at that distant site. Although much remains to be learned about the second phase, we feel that an understanding of the first phase is now within sight, due in part to a better understanding of how cancer cell behavior can be modified by a cell-biological program called the epithelial-to-mesenchymal transition.

3,993 citations

Journal ArticleDOI
TL;DR: Triple-negative breast cancer, so called because it lacks expression of the estrogen receptor, progesterone receptor, and HER2, is often, but not always, a basal-like breast cancer.
Abstract: Triple-negative breast cancer, so called because it lacks expression of the estrogen receptor, progesterone receptor, and HER2, is often, but not always, a basal-like breast cancer. This review focuses on its origin, molecular and clinical characteristics, and treatment.

3,125 citations

Journal ArticleDOI
26 Aug 2010-Oncogene
TL;DR: This review will provide potential mechanistic explanations for the association between EMT induction and the emergence of CSCs, and highlight recent studies implicating the function of TGF-β-regulated noncoding RNAs in driving EMT and promoting CSC self-renewal.
Abstract: Tumors are cellularly and molecularly heterogeneous, with subsets of undifferentiated cancer cells exhibiting stem cell-like features (CSCs). Epithelial to mesenchymal transitions (EMT) are transdifferentiation programs that are required for tissue morphogenesis during embryonic development. The EMT process can be regulated by a diverse array of cytokines and growth factors, such as transforming growth factor (TGF)-β, whose activities are dysregulated during malignant tumor progression. Thus, EMT induction in cancer cells results in the acquisition of invasive and metastatic properties. Recent reports indicate that the emergence of CSCs occurs in part as a result of EMT, for example, through cues from tumor stromal components. Recent evidence now indicates that EMT of tumor cells not only causes increased metastasis, but also contributes to drug resistance. In this review, we will provide potential mechanistic explanations for the association between EMT induction and the emergence of CSCs. We will also highlight recent studies implicating the function of TGF-β-regulated noncoding RNAs in driving EMT and promoting CSC self-renewal. Finally we will discuss how EMT and CSCs may contribute to drug resistance, as well as therapeutic strategies to overcome this clinically.

2,342 citations

Journal ArticleDOI
TL;DR: It is confirmed that a prognostically relevant differentiation hierarchy exists across all breast cancers in which the claudin-low subtype most closely resembles the mammary epithelial stem cell.
Abstract: Introduction In breast cancer, gene expression analyses have defined five tumor subtypes (luminal A, luminal B, HER2-enriched, basal-like and claudin-low), each of which has unique biologic and prognostic features. Here, we comprehensively characterize the recently identified claudin-low tumor subtype.

1,991 citations