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MiR-210 promotes a hypoxic phenotype and increases radioresistance in human lung cancer cell lines.

ABSTRACT: The resistance of hypoxic cells to radiotherapy and chemotherapy is a major problem in the treatment of cancer. Recently, an additional level of Hypoxia Inducible Factor (HIF) dependent transcriptional regulation has emerged involving modulation of a specific set of miRNAs including miR-210. We have recently shown that HIF-1 induction of miR-210 also stabilizes HIF-1 through a positive regulatory loop. We therefore hypothesized that by stabilizing HIF-1 in normoxia, miR-210 may protect cancer cells from radiation. We developed Non-Small Cell Lung Cancer (NSCLC)-derived cell lines (A549 and H1975) stably expressing miR-210 (pmiR-210) or a control miRNA (pmiR-Ctl). MiR-210 expressing cells showed a significant stabilization of HIF-1 associated with mitochondrial defects and a glycolytic phenotype. The cells were subjected to radiation levels ranging from 0 to 10Gy in normoxia and hypoxia. Cells expressing miR-210 in normoxia had the same level of resistance than control cells in hypoxia. pmiR-210 cells under hypoxia showed a low mortality rate due to a decrease in apoptosis and an ability to grow even at 10Gy. We have established that radioresistance was independent of p53 and cell cycle status. In addition, we show here that genomic double strand breaks (DSB) foci disappeared faster in pmiR-210 than in pmiR-Ctl cells, suggesting that miR-210 expression promotes a more efficient DSB repair. Finally, HIF-1 invalidation in pmiR-210 cells (pmiR-210/HIF-1-) abolished radioresistance of cells showing that this mechanism was dependent upon HIF-1. In conclusion, miR-210 appears to be a major component in the radioresistance of hypoxic cancer cells. Given the high stability of most miRNAs, this advantage could even be used by tumor cells in conditions where hypoxia may not be present anymore and strongly suggests that strategies targeting miR-210 would enhance tumor radiosensitization.

ORGANISM(S): Homo sapiens

PROVIDER: GSE43622 | GEO | 2013/04/01

SECONDARY ACCESSION(S): PRJNA186848

REPOSITORIES: GEO

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Project description:The resistance of hypoxic cells to radiotherapy and chemotherapy is a major problem in the treatment of cancer. Recently, an additional level of Hypoxia Inducible Factor (HIF) dependent transcriptional regulation has emerged involving modulation of a specific set of miRNAs including miR-210. We have recently shown that HIF-1 induction of miR-210 also stabilizes HIF-1 through a positive regulatory loop. We therefore hypothesized that by stabilizing HIF-1 in normoxia, miR-210 may protect cancer cells from radiation. We developed Non-Small Cell Lung Cancer (NSCLC)-derived cell lines (A549 and H1975) stably expressing miR-210 (pmiR-210) or a control miRNA (pmiR-Ctl). MiR-210 expressing cells showed a significant stabilization of HIF-1 associated with mitochondrial defects and a glycolytic phenotype. The cells were subjected to radiation levels ranging from 0 to 10Gy in normoxia and hypoxia. Cells expressing miR-210 in normoxia had the same level of resistance than control cells in hypoxia. pmiR-210 cells under hypoxia showed a low mortality rate due to a decrease in apoptosis and an ability to grow even at 10Gy. We have established that radioresistance was independent of p53 and cell cycle status. In addition, we show here that genomic double strand breaks (DSB) foci disappeared faster in pmiR-210 than in pmiR-Ctl cells, suggesting that miR-210 expression promotes a more efficient DSB repair. Finally, HIF-1 invalidation in pmiR-210 cells (pmiR-210/HIF-1-) abolished radioresistance of cells showing that this mechanism was dependent upon HIF-1. In conclusion, miR-210 appears to be a major component in the radioresistance of hypoxic cancer cells. Given the high stability of most miRNAs, this advantage could even be used by tumor cells in conditions where hypoxia may not be present anymore and strongly suggests that strategies targeting miR-210 would enhance tumor radiosensitization. To identify the set of transcripts targeted by miR-210, we overexpressed has-miR-210 or a control miRNA (ce-miR-67) in human lung adenocarcinoma A549 cells by transduction using lentivirus. The resulting pmiR-67 and pmiR-210 that stably overexpress miR-210 were selected by puromycin. RNA samples were harvested at 2 different times following cell plating (24 hours or 48 hours). Experiments were performed in dye-swap.

Project description:Recent studies have identified miR-210 among a set of hypoxia-regulated miRNAs, and shown the central regulatory role played by HIF to control transcription of this miRNA. Contradictory data exist concerning the regulation and roles of miR-210 during cancer progression. miR-210 appears at the same time over-expressed in some solid tumors (breast, pancreas, head and neck carcinomas, gliomas) while often deleted in ovarian carcinoma. It has been shown that depending on the tissue type or cellular model, miR-210 was indeed able to either promote entry into the cell cycle and to inhibit apoptosis or rather repress tumor initiation. We show here deregulation of several miRNAs in human lung cancer biopsies, including an over-expression of miR-210 which appears specific of late-stages of the tumor (>stage 2). MiR-210 function was then analyzed in the lung adenocarcinoma cell line A549. We found that miR-210 induced a delayed inhibition of proliferation associated with an induction of cell death. We also observed that mir-210 induces a loss of mitochondrial membrane potential and the apparition of an aberrant mitochondrial phenotype. mRNA expression profiling of cells overexpressing mir-210 revealed a specific signature characterized by an enrichment in mir-210 predicted targets among the downregulated transcripts (57 out of 243, p<10-12). Functional annotation of this set of mir-210-regulated transcripts, which includes several subunits of Electron Transport Chain (ETC) complex I and complex II revealed enrichment for terms such as 'cell death' and 'mitochondrial dysfunction'. Two of these ETC subunits, predicted to be targets of mir-210 by several bioinformatics prediction tools, were experimentally confirmed after cloning of their respective 3'UTR in a luciferase reporter vector. Finally, we provide experimental evidence indicating that these mitochondrial alterations could modulate HIF via a positive regulatory loop. Overall, our data strongly suggest that mir-210 could mediate two apparently opposite functions: i) apoptosis through targeting of specific mitochondrial components ii) a modulation of HIF through a positive regulatory loop. We propose that this dual behavior can explain the contradictory data regarding the impact of miR-210 during cancer progression. Refer to individual Series. This SuperSeries is composed of the following subset Series: GSE18692: MiRNA and lung cancer (INCA project) - 40 miRNAs microarrays GSE18694: MiRNA and lung cancer (INCA project) - 26 RNG25k microarrays GSE18695: MiRNA and lung cancer (INCA Project) - 66 RNG25k microarrays

Project description:Recent studies have identified miR-210 among a set of hypoxia-regulated miRNAs, and shown the central regulatory role played by HIF to control transcription of this miRNA. Contradictory data exist concerning the regulation and roles of miR-210 during cancer progression. miR-210 appears at the same time over-expressed in some solid tumors (breast, pancreas, head and neck carcinomas, gliomas) while often deleted in ovarian carcinoma. It has been shown that depending on the tissue type or cellular model, miR-210 was indeed able to either promote entry into the cell cycle and to inhibit apoptosis or rather repress tumor initiation. We show here deregulation of several miRNAs in human lung cancer biopsies, including an over-expression of miR-210 which appears specific of late-stages of the tumor (>stage 2). MiR-210 function was then analyzed in the lung adenocarcinoma cell line A549. We found that miR-210 induced a delayed inhibition of proliferation associated with an induction of cell death. We also observed that mir-210 induces a loss of mitochondrial membrane potential and the apparition of an aberrant mitochondrial phenotype. mRNA expression profiling of cells overexpressing mir-210 revealed a specific signature characterized by an enrichment in mir-210 predicted targets among the downregulated transcripts (57 out of 243, p<10-12). Functional annotation of this set of mir-210-regulated transcripts, which includes several subunits of Electron Transport Chain (ETC) complex I and complex II revealed enrichment for terms such as 'cell death' and 'mitochondrial dysfunction'. Two of these ETC subunits, predicted to be targets of mir-210 by several bioinformatics prediction tools, were experimentally confirmed after cloning of their respective 3'UTR in a luciferase reporter vector. Finally, we provide experimental evidence indicating that these mitochondrial alterations could modulate HIF via a positive regulatory loop. Overall, our data strongly suggest that mir-210 could mediate two apparently opposite functions: i) apoptosis through targeting of specific mitochondrial components ii) a modulation of HIF through a positive regulatory loop. We propose that this dual behavior can explain the contradictory data regarding the impact of miR-210 during cancer progression. This SuperSeries is composed of the SubSeries listed below.

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MiR-210 promotes a hypoxic phenotype and increases radioresistance in human lung cancer cell lines.

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