Dataset Information

Induction of cellular senescence by doxorubicin is associated with upregulated miR-375 and induction of autophagy in K562 cells.

ABSTRACT:

Background

Cellular senescence is a specialized form of growth arrest that is generally irreversible. Upregulated p16, p53, and p21 expression and silencing of E2F target genes have been characterized to promote the establishment of senescence. It can be further aided by the transcriptional repression of proliferation-associated genes by the action of HP1?, HMGA, and DNMT proteins to produce a repressive chromatin environment. Therefore, senescence has been suggested to functions as a natural brake for tumor development and plays a critical role in tumor suppression and aging.

Methodology/principal findings

An in vitro senescence model has been established by using K562 cells treated with 50 nM doxorubicin (DOX). Since p53 and p16 are homozygously deleted in the K562 cells, the DOX-induced senescence in K562 cells ought to be independent of p53 and p16-pRb pathways. Indeed, no change in the expression of the typical senescence-associated premalignant cell markers in the DOX-induced senescent K562 cells was found. MicroRNA profiling revealed upregulated miR-375 in DOX-induced senescent K562 cells. Treatment with miR-375 inhibitor was able to reverse the proliferation ability suppressed by DOX (p<0.05) and overexpression of miR-375 suppressed the normal proliferation of K562 cells. Upregulated miR-375 expression was associated with downregulated expression of 14-3-3zeta and SP1 genes. Autophagy was also investigated since DOX treatment was able to induce cells entering senescence and eventually lead to cell death. Among the 24 human autophagy-related genes examined, a 12-fold increase of ATG9B at day 4 and a 20-fold increase of ATG18 at day 2 after DOX treatment were noted.

Conclusions/significance

This study has demonstrated that in the absence of p53 and p16, the induction of senescence by DOX was associated with upregulation of miR-375 and autophagy initiation. The anti-proliferative function of miR-375 is possibly exerted, at least in part, by targeting 14-3-3zeta and SP1 genes.

SUBMITTER: Yang MY

PROVIDER: S-EPMC3350486 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Induction of cellular senescence by doxorubicin is associated with upregulated miR-375 and induction of autophagy in K562 cells.

Yang Ming-Yu MY Lin Pai-Mei PM Liu Yi-Chang YC Hsiao Hui-Hua HH Yang Wen-Chi WC Hsu Jui-Feng JF Hsu Cheng-Ming CM Lin Sheng-Fung SF

PloS one 20120511 5

<h4>Background</h4>Cellular senescence is a specialized form of growth arrest that is generally irreversible. Upregulated p16, p53, and p21 expression and silencing of E2F target genes have been characterized to promote the establishment of senescence. It can be further aided by the transcriptional repression of proliferation-associated genes by the action of HP1γ, HMGA, and DNMT proteins to produce a repressive chromatin environment. Therefore, senescence has been suggested to functions as a na ...[more]

PMID: 22606351

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Project description:Osteoarthritis (OA) is a chronic joint disease characterized by articular cartilage calcification, loss of articular cartilage, bone changes, pain, and disability. Cartilage calcification is one hallmark of OA and is predominantly caused by basic calcium crystals formed due to an imbalance of the pyrophosphate pathway. Sortilin is a transmembrane protein that contributes to vascular calcification in atherosclerosis by externalizing alkaline phosphatase (ALP)-containing vesicles. Calcification in atherosclerosis and osteoarthritis has been associated with cellular senescence. The aim of this study was to investigate the potential role of sortilin and senescence in osteoarthritis-dependent cartilage calcification. Osteoarthritic cartilage from human knee joints was collected after joint replacement, and samples were analyzed by immunohistochemistry and quantitative RT-PCR analysis. Human chondrocytes were treated with osteogenic medium for up to 21 days to induce calcification. Western blots for sortilin and ALP, as well as an ALP activity assay, were performed. Human chondrocytes were treated with mitomycin C to induce senescence, and sortilin expression was quantified at the protein and gene levels. Sections of knee joints from a murine model of osteoarthritis were stained for sortilin and p16 and analyzed by immunohistochemistry. Treatment of wild-type chondrocytes using an osteogenic medium similar to human chondrocytes was performed. Osteoarthritic cartilage from mouse and human knee joints showed an increased number of sortilin and p16-positive chondrocytes compared to healthy cartilage. This observation was corroborated by increased gene expression of sortilin and p16 in mild and moderate osteoarthritic cartilage samples. To investigate the mechanism of sortilin regulation, human chondrocytes were treated with osteogenic medium to induce calcification. Sortilin protein levels and expression were increased after 7 days of stimulation, whereas ALP levels and activity were upregulated after 21 days of stimulation. Similar observations were made in a murine osteoarthritis model. Mechanistically, senescent chondrocytes induced by mitomycin C showed an upregulation of sortilin and ALP gene expression compared to non-senescent chondrocytes. Our data indicate that sortilin and ALP are upregulated during cartilage calcification, which is associated with chondrocyte senescence and thus might contribute to the pathogenesis of osteoarthritis. Cellular senescence seems to induce sortilin expression.

Dataset Information

Induction of cellular senescence by doxorubicin is associated with upregulated miR-375 and induction of autophagy in K562 cells.

Background

Methodology/principal findings

Conclusions/significance

Publications

Induction of cellular senescence by doxorubicin is associated with upregulated miR-375 and induction of autophagy in K562 cells.

Similar Datasets

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