This SuperSeries is composed of the SubSeries listed below.
Reprogramming of the microRNA transcriptome mediates resistance to rapamycin.
Specimen part, Cell line
View SamplesThe mammalian target of rapamycin (mTOR) is a central regulator of cell proliferation. Inhibitors of mTOR are being evaluated as anti-tumor agents. Given the emerging role of microRNAs (miRNAs) in tumorgenesis we hypothesized that miRNAs could play important roles in the response of tumors to mTOR inhibitors. Rapamycin resistant myogenic cells developed by long-term rapamycin treatment showed extensive reprogramming of miRNAs expression, characterized by up-regulation of the mir-17~92 and related clusters and down-regulation of tumor-suppressor miRNAs. Antagonists of oncogenic miRNA families and mimics of tumor suppressor miRNAs (let-7) restored rapamycin sensitivity in resistant tumor cells. This study identified miRNAs as new downstream components of the mTOR-signaling pathway, which may determine the response of tumors to mTOR inhibitors.
Reprogramming of the microRNA transcriptome mediates resistance to rapamycin.
Specimen part, Cell line
View SamplesActivated phosphoinositide 3-kinase (PI3K)-AKT signaling appears to be an obligate event in the development of cancer. The highly related members of the mammalian FoxO transcription factor family, FoxO1, FoxO3, and FoxO4, represent one of several effector arms of PI3K-AKT signaling, prompting genetic analysis of the role of FoxOs in the neoplastic phenotypes linked to PI3K-AKT activation. While germline or somatic deletion of up to five FoxO alleles produced remarkably modest neoplastic phenotypes, broad somatic deletion of all FoxOs engendered a progressive cancer-prone condition characterized by thymic lymphomas and hemangiomas, demonstrating that the mammalian FoxOs are indeed bona fide tumor suppressors. Transcriptome and promoter analyses of differentially affected endothelium identified direct FoxO targets and revealed that FoxO regulation of these targets in vivo is highly context-specific, even in the same cell type. Functional studies validated Sprouty2 and PBX1, among others, as FoxO-regulated mediators of endothelial cell morphogenesis and vascular homeostasis.
FoxOs are lineage-restricted redundant tumor suppressors and regulate endothelial cell homeostasis.
Specimen part
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