1,721,720 research outputs found
Funda Meric-Bernstam, MD
Full text linkhttps://openworks.mdanderson.org/legendsandlegacieschapters/1015/thumbnail.jp
Targeting PI3K/mTOR Signaling in Cancer
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The American Association for Cancer Research (AACR) Special Conference on Targeting PI3K/mTOR Signaling in Cancer was held in San Francisco, California from February 24 to 27, 2011. The meeting was cochaired by Drs. Lewis C. Cantley, David M. Sabatini, and Funda Meric-Bernstam. The main focus of this event was the therapeutic potential of drugs targeting the PI3K/mTOR signaling pathway for the treatment of cancer. This article summarizes the recent discoveries in the field, with particular emphasis on the major themes of the conference. Cancer Res; 71(24); 7351–9. ©2011 AACR.</jats:p
Abstract 5399: Investigating phenotypic plasticity in breast cancer with high-throughput nanogrid single-nucleus RNA sequencing
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Single-cell RNA sequencing (RNA-seq) is a powerful tool for investigating rare tumor subpopulations and resolving intra-tumor heterogeneity, but is low throughput, expensive, and requires fresh tissue samples. To address these limitations, we developed a 5’ high-throughput single-nucleus RNA sequencing (SNRS) approach that uses nanogrid technology to perform single-cell imaging and sequencing of 500-2500 nuclei in parallel. The automated image scanning procedure allowed us to exclude doublets and select live cells with DAPI/PI staining. This approach allows the transcriptomic profiling of frozen tissue samples, in which the cytoplasmic membrane is ruptured in cells, but leaves the nuclear membrane intact. We validated SNRS in a breast cancer cell line (SK-BR-3) and compared the transcriptomes of 500 nuclei to 500 whole cells, which revealed a high concordance in the number of genes expressed as well as their expression levels. We also performed bulk RNA-seq of isolated nuclear and cellular fractions from 5 breast cancer cell lines, which showed a high concordance in genes and expression levels. Differentially expressed genes in the nucleus mainly included lincRNAs, pseudogenes and mitochondria genes, but did not affect most cancer genes and pathway analysis. We further applied SNRS to sequence 500 nuclei from a triple-negative breast cancer patient and identified diverse phenotypes in tumor cells, including variation in cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition. These studies demonstrated the technical feasibility of using a nanogrid platform to perform high-throughput single-cell RNA sequencing and showed that nuclei from cell lines and tumors can be used to study signaling pathways and gene networks that play an important role in tumor progression.
Citation Format: Ruli Gao, Charissa Kim, Emi Sei, Jie Yang, Leo Chan, Maithreyan Srinivasan, Hong Zhang, Funda Meric-Bernstam, Nicholas E. Navin. Investigating phenotypic plasticity in breast cancer with high-throughput nanogrid single-nucleus RNA sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5399. doi:10.1158/1538-7445.AM2017-5399</jats:p
Abstract 135: Targeted therapy of hormone receptor-positive breast cancer harboring <i>PIK3CA</i> and <i>AKT1</i> genetic aberrations
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Introduction: Molecular alterations in the PI3K/Akt/mTOR pathway is implicated in the pathogenesis of ER positive breast cancer with high frequency and therefore is the major focus of drug development. Activating mutations of this signaling pathway occur in more than 70% of breast tumors. The genetic alterations affecting major components of PI3K/Akt/mTOR include genes encoding the PI3K catalytic subunits p110α (PIK3CA) and the PI3K effector AKT1. Despite the efficacy of the available small molecule inhibitors for targeting different components of PI3K pathway, the contribution of PIK3CA and AKT1 genetic alterations to targeted therapy is not well understood. We speculated that ER positive breast tumors with PIK3CA and AKT1 alterations are more sensitive to PI3K and Akt inhibitors due to differential downstream pathway effectors.
Methods: We used a panel of isogenic MCF7 cell lines with oncogenic mutations of PIK3CA and AKT1 established through somatic cell gene targeting. A series of pharmacological compounds currently approved for breast cancer therapy or in clinical trials in targeting PI3K/Akt/mTOR pathway were evaluated using viability, clonogenic and cell cycle analysis assays. We performed functional proteomic profiling using reverse phase proteomic analysis (RPPA) to investigate differential protein expression in response to PI3K pathway inhibition in PIK3CA and AKT1 mutants MCF7 cell lines. In vivo experiment was done to evaluate the efficacy of the inhibitors in suppressing tumor growth.
Results: We demonstrated that PIK3CA (E545K) and AKT1 (E17K) sensitized cells to the inhibitory effects of BYL719 (p110α catalytic subunit inhibitor) and AZD5363 (pan-AKT kinase inhibitor) on survival, cell cycle progression and colony formation ability. The presence of PIK3CA and AKT1 mutations conferred growth advantage and exhibited increased proliferation in vitro and in vivo. These alterations dramatically increased Akt phosphorylation and induced activation of PI3K downstream effectors. RPPA analysis revealed several proteins differentially expressed in PIK3CA and AKT1 mutant cells compared with wild type (p-value &lt; 0.05).
Conclusion: PIK3CA and AKT1 mutations showed distinct effects on sensitivity to targeted pathway inhibitors in an isogenic luminal breast cancer model. The presence of these genetic alterations in estrogen receptor (ER) positive breast cancer provided proliferative advantage and enhanced their sensitivity to targeted PI3K inhibition. These results will contribute to identify single agent and combination therapies targeting PI3K pathway with maximal activity at tolerated dose and selection for individuals most likely to be responsive based on their genomic alterations.
Citation Format: Maryam Shariati, Kurt W. Evans, Stephen M. Scott, Huiqin Chen, Funda Meric-Bernstam. Targeted therapy of hormone receptor-positive breast cancer harboring PIK3CA and AKT1 genetic aberrations [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 135. doi:10.1158/1538-7445.AM2017-135</jats:p
Risk of Ipsilateral and Contralateral Cancer in BRCA Mutation Carriers with Breast Cancer
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