Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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PMCA2 Regulates HER2 Expression, Cell-Surface Localization and Signaling, and Promotes HER2- Mediated Breast Cancer

ABSTRACT: In the normal breast, PMCA2 transports calcium into milk. It is also upregulated in breast cancer cells and high tumor levels predict increased mortality in patients. In this study, we examined interactions between PMCA2 and HER2. We find that PMCA2 and a scaffolding protein, NHERF1, interact together with HER2 in specific membrane domains protruding from the surface of breast cancer cells. Knocking down PMCA2 or NHERF1 increases intracellular calcium and leads to the ubiquitination, endocytosis and degradation of HER2 after receptor activation. This is associated with reductions in HER2 expression and signaling. Manipulating PMCA2 levels regulates proliferation and apoptosis of breast cancer cells in vitro and knocking out PMCA2 dramatically inhibits the formation of hyperplasia and tumors in MMTV-Neu mice. Gene expression profiling was performed on control SKBR3 cells vs. PMCA2, NHERFR1 and HER2 knock down cells. Each group has 6 duplicates.

ORGANISM(S): Homo sapiens

SUBMITTER: Jaekwang Jeong

PROVIDER: E-GEOD-62555 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Circulating tumour cells in women with advanced oestrogen-receptor (ER)-positive/human epidermal growth factor receptor 2 (HER2)-negative breast cancer acquire a HER2-positive subpopulation after multiple courses of therapy. In contrast to HER2-amplified primary breast cancer, which is highly sensitive to HER2-targeted therapy, the clinical significance of acquired HER2 heterogeneity during the evolution of metastatic breast cancer is unknown. Here we analyse circulating tumour cells from 19 women with ER+/HER2- primary tumours, 84% of whom had acquired circulating tumour cells expressing HER2. Cultured circulating tumour cells maintain discrete HER2+ and HER2- subpopulations: HER2+ circulating tumour cells are more proliferative but not addicted to HER2, consistent with activation of multiple signalling pathways; HER2- circulating tumour cells show activation of Notch and DNA damage pathways, exhibiting resistance to cytotoxic chemotherapy, but sensitivity to Notch inhibition. HER2+ and HER2- circulating tumour cells interconvert spontaneously, with cells of one phenotype producing daughters of the opposite within four cell doublings. Although HER2+ and HER2- circulating tumour cells have comparable tumour initiating potential, differential proliferation favours the HER2+ state, while oxidative stress or cytotoxic chemotherapy enhances transition to the HER2- phenotype. Simultaneous treatment with paclitaxel and Notch inhibitors achieves sustained suppression of tumorigenesis in orthotopic circulating tumour cell-derived tumour models. Together, these results point to distinct yet interconverting phenotypes within patient-derived circulating tumour cells, contributing to progression of breast cancer and acquisition of drug resistance. Seventy-four single candidate CTCs from two representative ER+/HER2- patients (BRx-42 and BRx-82) and 14 triple negative patients were isolated via micromanipulation and subjected to single-cell RNA-sequencing. Thirteen candidate CTCs expressed PTPRC at a level higher than 10 reads-per-million, so were deemed potential White Blood Cells and therefore dropped from further consideration. Expression profiles of CTCs expressing ERBB2 at a level greater than 10 RPM were compared with those expressing ERBB2 at a level less than 10 RPM.

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PMCA2 Regulates HER2 Expression, Cell-Surface Localization and Signaling, and Promotes HER2- Mediated Breast Cancer

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