Circular RNA CpG Island Hypermethylation-Associated Silencing in Human Cancer
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ABSTRACT:
PROVIDER: PRJNA431634 | ENA |
REPOSITORIES: ENA
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Project description:Although less than 2% of the human genome code for proteins, most studies in cancer research has focused in this small portion of our DNA. However, it has been recognized in the last years that non-coding RNAs (ncRNAs) also participate in cellular transformation. In this context, microRNAs and long noncoding RNAs (lncRNAs) can act as oncogenes or tumor suppressor genes. Recent work have also demonstrated that ncRNAs with growth-inhibitory functions can undergo promoter CpG island hypermethylation-associated silencing in tumorigenesis. Herein, we wondered whether circular RNAs (circRNAs), a type of RNA transcripts lacking 5’-3´ends and forming closed loops that are gaining relevance in cancer biology, are also a target of epigenetic inactivation in tumors. To tackle this issue, we have used cancer cells genetically deficient for the DNA methyltransferase enzymes in conjuction with circRNA expression microarrays. We have found that the loss of DNA methylation provokes a release of circRNA silencing. We have particularly identified that promoter CpG island hypermethylation of the genes TUSC3 (tumor suppressor candidate 3), POMT1 (protein O-mannosyltransferase 1), ATRNL1 (attractin-like 1) and SAMD4A (sterile alpha motif domain containing 4A) is linked to the transcriptional downregulation of both linear mRNA and the hosted circRNA. Although a role in the control of the parental gene has been shown for some circRNAs, we did not observe changes in TUSC mRNA levels upon TUSC3 circ104557 overexpression. Most importantly, data mining for 5’-end CpG island methylation of TUSC3, ATRNL1, POMT1 and SAMD4A in a large collection of human cancer cell lines and primary tumors showed that the epigenetic defect was commonly observed among different tumor types, where it was also associated with the diminished expression of the corresponding transcript. Our findings support a role for circRNA DNA methylation-associated loss in human cancer.
2018-06-13 | GSE109676 | GEO
Project description:Astrocytomas are common and lethal human brain tumors. Here, we have analyzed the methylation status of over 28,000 CpG islands and 18,000 promoters in normal human brain and in astrocytomas of various grades using the methylated-CpG island recovery assay (MIRA). We identified six to seven thousand methylated CpG islands in normal human brain. ~5% of the promoter-associated CpG islands in normal brain are methylated. Promoter CpG island methylation is inversely and intragenic methylation is directly correlated with gene expression levels in brain tissue. In astrocytomas, several hundred CpG islands undergo specific hypermethylation relative to normal brain with 428 methylation peaks common to more than 25% of the tumors. Genes involved in brain development and neuronal differentiation, such as POU4F3, GDNF, OTX2, NEFM, CNTN4, OTP, SIM1, FYN, EN1, CHAT, GSX2, NKX6-1, RAX, PAX6, DLX2, were strongly enriched among genes frequently methylated in tumors. There was an overrepresentation of homeobox genes and 31% of the most commonly methylated genes represent targets of the Polycomb complex. We identified several chromosomal loci in which many (sometimes more than 20) consecutive CpG islands were hypermethylated in tumors. Seven of such loci were near homeobox genes, including the HOXC and HOXD clusters, and the BARHL2, DLX1, and PITX2 genes. Two other clusters of hypermethylated islands were at sequences of recent gene duplication events. Our analysis offers mechanistic insights into brain neoplasia suggesting that methylation of genes involved in neuronal differentiation, perhaps in cooperation with other oncogenic events, may shift the balance from regulated differentiation towards gliomagenesis.
2010-01-01 | GSE19391 | GEO
Project description:Astrocytomas are common and lethal human brain tumors. Here, we have analyzed the methylation status of over 28,000 CpG islands and 18,000 promoters in normal human brain and in astrocytomas of various grades using the methylated-CpG island recovery assay (MIRA). We identified six to seven thousand methylated CpG islands in normal human brain. ~5% of the promoter-associated CpG islands in normal brain are methylated. Promoter CpG island methylation is inversely and intragenic methylation is directly correlated with gene expression levels in brain tissue. In astrocytomas, several hundred CpG islands undergo specific hypermethylation relative to normal brain with 428 methylation peaks common to more than 25% of the tumors. Genes involved in brain development and neuronal differentiation, such as POU4F3, GDNF, OTX2, NEFM, CNTN4, OTP, SIM1, FYN, EN1, CHAT, GSX2, NKX6-1, RAX, PAX6, DLX2, were strongly enriched among genes frequently methylated in tumors. There was an overrepresentation of homeobox genes and 31% of the most commonly methylated genes represent targets of the Polycomb complex. We identified several chromosomal loci in which many (sometimes more than 20) consecutive CpG islands were hypermethylated in tumors. Seven of such loci were near homeobox genes, including the HOXC and HOXD clusters, and the BARHL2, DLX1, and PITX2 genes. Two other clusters of hypermethylated islands were at sequences of recent gene duplication events. Our analysis offers mechanistic insights into brain neoplasia suggesting that methylation of genes involved in neuronal differentiation, perhaps in cooperation with other oncogenic events, may shift the balance from regulated differentiation towards gliomagenesis. Comparison of methylation patterns of 30 astrocytomas and 6 controls
2010-05-16 | E-GEOD-19391 | biostudies-arrayexpress
Project description:Noncoding RNAs (ncRNAs), such as microRNAs and long noncoding RNAs (lncRNAs), participate in cellular transformation. Work done in the last decade has also demonstrated that ncRNAs with growth-inhibitory functions can undergo promoter CpG island hypermethylation-associated silencing in tumorigenesis. Herein, we wondered whether circular RNAs (circRNAs), a type of RNA transcripts lacking 5'-3' ends and forming closed loops that are gaining relevance in cancer biology, are also a target of epigenetic inactivation in tumors. To tackle this issue, we have used cancer cells genetically deficient for the DNA methyltransferase enzymes in conjuction with circRNA expression microarrays. We have found that the loss of DNA methylation provokes a release of circRNA silencing. In particular, we have identified that promoter CpG island hypermethylation of the genes TUSC3 (tumor suppressor candidate 3), POMT1 (protein O-mannosyltransferase 1), ATRNL1 (attractin-like 1) and SAMD4A (sterile alpha motif domain containing 4A) is linked to the transcriptional downregulation of both linear mRNA and the hosted circRNA. Although some circRNAs regulate the linear transcript, we did not observe changes in TUSC3 mRNA levels upon TUSC3 circ104557 overexpression. Interestingly, we found circRNA-mediated regulation of target miRNAs and an in vivo growth inhibitory effect upon TUSC3 circ104557 transduction. Data mining for 5'-end CpG island methylation of TUSC3, ATRNL1, POMT1 and SAMD4A in cancer cell lines and primary tumors showed that the epigenetic defect was commonly observed among different tumor types in association with the diminished expression of the corresponding transcript. Our findings support a role for circRNA DNA methylation-associated loss in human cancer.
| S-EPMC6044373 | biostudies-literature
Project description:DNA methylation plays a key role in demarcation of regulatory regions, including promoter-associated CpG islands. While CpG islands are typically maintained in an unmethylated state in normal cells, a proportion of CpG islands are subject to hypermethylation in cancer cells. It still remains elusive how the exquisite demarcation of the bimodal methylation state is established and maintained at the CpG island flanks and conversely what triggers the erosion of CpG island DNA methylation in tumorigenesis. Here, we applied whole-genome bisulphite sequencing to study the comprehensive methylation patterns of prostate normal and cancer tissues. Alongside we performed TET-assisted bisulphite sequencing to study genome-wide DNA hydroxymethylation patterns of normal prostate and prostate cancer tissues.
2019-01-23 | GSE104789 | GEO
Project description:Cancer cells display DNA hypermethylation at specific CpG islands in comparison to their normal healthy counterparts, but the mechanism that drives this so-called CpG island methylator phenotype (CIMP) remains poorly understood. Here, we show that CpG island methylation in human T-cell acute lymphoblastic leukemia (T-ALL) mainly occurs at promoters of PRC2 target genes that are not expressed in normal or malignant T-cells and which display a reciprocal association with H3K27me3 binding. In addition, we found that this aberrant methylation profile shows a strong correlation with the epigenetic age of the leukemic T cells and elucidate that a similar CpG island methylation signature is gradually established in aging pre-leukemic thymocytes from CD2-Lmo2 transgenic mice. Finally, we unexpectedly uncover that this age-related CpG island hypermethylation signature is completely resistant to the FDA-approved hypomethylating agent Decitabine. Altogether, our work demonstrates that DNA methylation reflects the epigenetic history of leukemic T cells and suggests that methylation-based subtypes of human T-ALL have followed a different trajectory towards T-cell transformation, possibly mediated by differences in the self-renewing capacity of the putative T-ALL cell-of-origin. Given that the concept of preleukemic thymocytes has only been reported in T-ALL mouse models so far, we here provide, for the first time, conceptual evidence that a pre-leukemic phase might also be involved in the pathogenesis of the human disease.
2020-09-24 | GSE155335 | GEO
Project description:Cancer cells display DNA hypermethylation at specific CpG islands in comparison to their normal healthy counterparts, but the mechanism that drives this so-called CpG island methylator phenotype (CIMP) remains poorly understood. Here, we show that CpG island methylation in human T-cell acute lymphoblastic leukemia (T-ALL) mainly occurs at promoters of PRC2 target genes that are not expressed in normal or malignant T-cells and which display a reciprocal association with H3K27me3 binding. In addition, we found that this aberrant methylation profile shows a strong correlation with the epigenetic age of the leukemic T cells and elucidate that a similar CpG island methylation signature is gradually established in aging pre-leukemic thymocytes from CD2-Lmo2 transgenic mice. Finally, we unexpectedly uncover that this age-related CpG island hypermethylation signature is completely resistant to the FDA-approved hypomethylating agent Decitabine. Altogether, our work demonstrates that DNA methylation reflects the epigenetic history of leukemic T cells and suggests that methylation-based subtypes of human T-ALL have followed a different trajectory towards T-cell transformation, possibly mediated by differences in the self-renewing capacity of the putative T-ALL cell-of-origin. Given that the concept of preleukemic thymocytes has only been reported in T-ALL mouse models so far, we here provide, for the first time, conceptual evidence that a pre-leukemic phase might also be involved in the pathogenesis of the human disease.
2020-09-24 | GSE155338 | GEO
Project description:Cancer cells display DNA hypermethylation at specific CpG islands in comparison to their normal healthy counterparts, but the mechanism that drives this so-called CpG island methylator phenotype (CIMP) remains poorly understood. Here, we show that CpG island methylation in human T-cell acute lymphoblastic leukemia (T-ALL) mainly occurs at promoters of PRC2 target genes that are not expressed in normal or malignant T-cells and which display a reciprocal association with H3K27me3 binding. In addition, we found that this aberrant methylation profile shows a strong correlation with the epigenetic age of the leukemic T cells and elucidate that a similar CpG island methylation signature is gradually established in aging pre-leukemic thymocytes from CD2-Lmo2 transgenic mice. Finally, we unexpectedly uncover that this age-related CpG island hypermethylation signature is completely resistant to the FDA-approved hypomethylating agent Decitabine. Altogether, our work demonstrates that DNA methylation reflects the epigenetic history of leukemic T cells and suggests that methylation-based subtypes of human T-ALL have followed a different trajectory towards T-cell transformation, possibly mediated by differences in the self-renewing capacity of the putative T-ALL cell-of-origin. Given that the concept of preleukemic thymocytes has only been reported in T-ALL mouse models so far, we here provide, for the first time, conceptual evidence that a pre-leukemic phase might also be involved in the pathogenesis of the human disease.
2020-09-24 | GSE155337 | GEO
Project description:Cancer cells display DNA hypermethylation at specific CpG islands in comparison to their normal healthy counterparts, but the mechanism that drives this so-called CpG island methylator phenotype (CIMP) remains poorly understood. Here, we show that CpG island methylation in human T-cell acute lymphoblastic leukemia (T-ALL) mainly occurs at promoters of PRC2 target genes that are not expressed in normal or malignant T-cells and which display a reciprocal association with H3K27me3 binding. In addition, we found that this aberrant methylation profile shows a strong correlation with the epigenetic age of the leukemic T cells and elucidate that a similar CpG island methylation signature is gradually established in aging pre-leukemic thymocytes from CD2-Lmo2 transgenic mice. Finally, we unexpectedly uncover that this age-related CpG island hypermethylation signature is completely resistant to the FDA-approved hypomethylating agent Decitabine. Altogether, our work demonstrates that DNA methylation reflects the epigenetic history of leukemic T cells and suggests that methylation-based subtypes of human T-ALL have followed a different trajectory towards T-cell transformation, possibly mediated by differences in the self-renewing capacity of the putative T-ALL cell-of-origin. Given that the concept of preleukemic thymocytes has only been reported in T-ALL mouse models so far, we here provide, for the first time, conceptual evidence that a pre-leukemic phase might also be involved in the pathogenesis of the human disease.
2020-09-24 | GSE155336 | GEO
Project description:Cancer cells display DNA hypermethylation at specific CpG islands in comparison to their normal healthy counterparts, but the mechanism that drives this so-called CpG island methylator phenotype (CIMP) remains poorly understood. Here, we show that CpG island methylation in human T-cell acute lymphoblastic leukemia (T-ALL) mainly occurs at promoters of PRC2 target genes that are not expressed in normal or malignant T-cells and which display a reciprocal association with H3K27me3 binding. In addition, we found that this aberrant methylation profile shows a strong correlation with the epigenetic age of the leukemic T cells and elucidate that a similar CpG island methylation signature is gradually established in aging pre-leukemic thymocytes from CD2-Lmo2 transgenic mice. Finally, we unexpectedly uncover that this age-related CpG island hypermethylation signature is completely resistant to the FDA-approved hypomethylating agent Decitabine. Altogether, our work demonstrates that DNA methylation reflects the epigenetic history of leukemic T cells and suggests that methylation-based subtypes of human T-ALL have followed a different trajectory towards T-cell transformation, possibly mediated by differences in the self-renewing capacity of the putative T-ALL cell-of-origin. Given that the concept of preleukemic thymocytes has only been reported in T-ALL mouse models so far, we here provide, for the first time, conceptual evidence that a pre-leukemic phase might also be involved in the pathogenesis of the human disease.
2020-09-24 | GSE155334 | GEO