Východiska: Výzkum posledního desetiletí potvrdil význam epigenetických procesů při vzniku, vývoji a léčbě nádorových onemocnění. Především sekvenování nové generace umožnilo zmapovat lidský epigenom a sledovat jeho změny během kancerogeneze. Tento přístup odhalil přímá napojení epigenetických abnormalit na mutace genů, které kontrolují metylaci DNA, sbalování a funkci DNA v chromatinu, nebo na metabolizmus buněk. Epigenetické změny DNA se vyskytují už v časných fázích vývoje nádorových onemocnění, a jsou tedy slibnými kandidáty na diagnostické a prognostické markery a současně epigenetické procesy představují vhodné cíle pro vývoj nových terapeutických látek. Získané poznatky o aberantní metylaci DNA umožňují dva různé pohledy na to, jak daná modifikace přispívá k vývoji nádorového onemocnění. První pohled předpokládá, že normální buňky podléhají transformaci vlivem řídicích mutací, kdy následné metylace de novo a demetylace DNA přispívají k řadě programových změn genové exprese. Alternativní přístup pohlíží na změny v metylaci DNA jako na důsledek např. stárnutí buněk. A právě tyto získané změny zvyšují citlivost DNA ke vzniku mutací a k následné onkogenní transformaci. Cíle: Cílem přehledového článku je shrnout dosud známé úlohy abnormální metylace DNA při vývoji nádorového onemocnění a představit již publikovanou alternativní teorii, která k dané problematice přistupuje méně obvyklým způsobem.
Background: Research in the last decade has confirmed the importance of epigenetic processes for the onset, development, and treatment of cancer. Next generation sequencing has allowed the inspection and mapping of the human epigenome and its monitoring for changes during carcinogenesis, which has revealed direct links between epigenetic abnormalities and mutations in genes that control DNA methylation and packing and those that function in chromatin dynamics and metabolism. Epigenetic changes that occur in the early stages of tumor progression thus represent promising candidates for diagnostic and prognostic markers, and epigenetic processes are suitable targets for the development of new therapeutic strategies. There are two contrasting views on how aberrant DNA methylation contributes to the development of cancer. The first view assumes that normal cells undergo transformation due to driver mutations and subsequent de novo methylation and DNA demethylation, resulting in global changes in gene expression. The second view considers changes in DNA methylation to be a consequence of cell aging, for example, and that the acquired changes increase the sensitivity of DNA to mutations and oncogenic transformation. Aims: The aim of the review article is to briefly summarize the role of abnormal DNA methylation in the development of cancer, and to present an alternative theory that considers the role of aberrant DNA methylation patterns in cancer from a new and unconventional perspective.
- MeSH
- CpG Islands MeSH
- Humans MeSH
- DNA Methylation * MeSH
- Neoplasms * etiology genetics MeSH
- Polycomb-Group Proteins MeSH
- Check Tag
- Humans MeSH
- Publication type
- Review MeSH
RNA methylation, especially 6-methyladenosine (m6A)-modified RNAs, plays a specific role in DNA damage response (DDR). Here, we also observe that RNA modified at 8-methyladenosine (m8A) is recruited to UVA-damaged chromatin immediately after microirradiation. Interestingly, the level of m8A RNA at genomic lesions was reduced after inhibition of histone deacetylases and DNA methyltransferases. It appears in later phases of DNA damage response, accompanied by active DNA demethylation. Also, PARP inhibitor (PARPi), Olaparib, prevented adenosine methylation at microirradiated chromatin. PARPi abrogated not only m6A and m8A RNA positivity at genomic lesions, but also XRCC1, the factor of base excision repair (BER), did not recognize lesions in DNA. To this effect, Olaparib enhanced the genome-wide level of γH2AX. This histone modification interacted with m8A RNAs to a similar extent as m8A RNAs with DNA. Pronounced interaction properties we did not observe for m6A RNAs and DNA; however, m6A RNA interacted with XRCC1 with the highest efficiency, especially in microirradiated cells. Together, we show that the recruitment of m6A RNA and m8A RNA to DNA lesions is PARP dependent. We suggest that modified RNAs likely play a role in the BER mechanism accompanied by active DNA demethylation. In this process, γH2AX stabilizes m6A/m8A-positive RNA-DNA hybrid loops via its interaction with m8A RNAs. R-loops could represent basic three-stranded structures recognized by PARP-dependent non-canonical m6A/m8A-mediated DNA repair pathway.
The DNA damage response is mediated by both DNA repair proteins and epigenetic markers. Here, we observe that N6-methyladenosine (m6A), a mark of the epitranscriptome, was common in RNAs accumulated at UV-damaged chromatin; however, inhibitors of RNA polymerases I and II did not affect the m6A RNA level at the irradiated genomic regions. After genome injury, m6A RNAs either diffused to the damaged chromatin or appeared at the lesions enzymatically. DNA damage did not change the levels of METTL3 and METTL14 methyltransferases. In a subset of irradiated cells, only the METTL16 enzyme, responsible for m6A in non-coding RNAs as well as for splicing regulation, was recruited to microirradiated sites. Importantly, the levels of the studied splicing factors were not changed by UVA light. Overall, if the appearance of m6A RNAs at DNA lesions is regulated enzymatically, this process must be mediated via the coregulatory function of METTL-like enzymes. This event is additionally accompanied by radiation-induced depletion of 2,2,7-methylguanosine (m3G/TMG) in RNA. Moreover, UV-irradiation also decreases the global cellular level of N1-methyladenosine (m1A) in RNAs. Based on these results, we prefer a model in which m6A RNAs rapidly respond to radiation-induced stress and diffuse to the damaged sites. The level of both (m1A) RNAs and m3G/TMG in RNAs is reduced as a consequence of DNA damage, recognized by the nucleotide excision repair mechanism.
- MeSH
- Adenosine analogs & derivatives metabolism MeSH
- Chromatin metabolism MeSH
- DNA Demethylation radiation effects MeSH
- Stress, Physiological radiation effects MeSH
- Guanosine analogs & derivatives metabolism MeSH
- DNA Methylation genetics radiation effects MeSH
- Methylation radiation effects MeSH
- Mice MeSH
- Cell Line, Tumor MeSH
- RNA, Untranslated metabolism MeSH
- Genomic Instability radiation effects MeSH
- DNA Damage MeSH
- RNA metabolism MeSH
- Ultraviolet Rays * MeSH
- Animals MeSH
- Check Tag
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Recent studies have highlighted the significant role of 5-hydroxymethylcytosine (5hmC) in carcinogenesis. However, the specific role of 5hmC in osteosarcoma (OS) remains largely unexplored. The-re-fore, this study aimed to investigate the function of 5hmC and TET3 in OS. In this study, we found a decreased total level of 5hmC in OS tissues. The expression of the TET3 protein was also decreased in OS. Importantly, the decreased levels of TET3 were associated with a decreased disease-free survival (DFS) rate in patients. To investigate the role of TET3 and 5hmC in OS, we manipulated the levels of TET3 in MG-63 cells. Silencing TET3 in these cells resulted in a twofold increase in proliferation. Additio-nally, the level of 5hmC decreased in these cells. Con-versely, over-expression of TET3 in MG-63 cells led to the expected inhibition of proliferation and invasion, accompanied by an increase in 5hmC levels. In conclusion, both 5hmC and TET3 protein levels were decreased in OS. Additionally, the over-expression of TET3 inhibited the proliferation of MG-63 cells, while the suppression of TET3 had the opposite effect. These findings suggest that decreased levels of 5hmC and TET3 may serve as potential markers for OS.
- MeSH
- 5-Methylcytosine * analogs & derivatives metabolism MeSH
- DNA Demethylation * MeSH
- Dioxygenases * metabolism MeSH
- Epigenesis, Genetic * MeSH
- Humans MeSH
- Cell Line, Tumor MeSH
- Bone Neoplasms genetics metabolism pathology MeSH
- Osteosarcoma genetics metabolism pathology MeSH
- Cell Proliferation * MeSH
- Proto-Oncogene Proteins metabolism genetics MeSH
- Gene Expression Regulation, Neoplastic MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
Závěrečná zpráva o řešení grantu Agentury pro zdravotnický výzkum MZ ČR
nestr.
Multiple myeloma (MM) is a still lethal plasma cell malignancy. Epigenetic mechanisms, such as DNA methylation are increasingly recognized as potent modulators of tumor cell survival and drug resistance. However, within the complex approach to the diagnostics, the contribution of DNA methylation has been discovered as important, druggable targets but have not been investigated in MM so far. Therefore, we aim to assess the impact of these modulations for MM pathogenesis and drug resistance. Specifically, we investigate the impact of DNA methylation pattern of prognostically important tumor-suppressor genes for MM. We will focus on the contribution of specific miRNA29 to methylation pattern and function of tumor suppressor genes. We will try to therapeutically modify (5 ́-Aza-2 ́-deoxycytidne) methylation patterns. Experiments will be performed also in a MM tumor-microenvironment model to mirror a possible in vivo relevance. Investigation of the usage of tumor-specific DNA methyltransferases and their possible therapeutic targeting are expected to open new avenues to combat MM.
Mnohočetný myelom (MM) vzniká jako důsledek vícestupňového transformačního procesu plazmatických buněk doprovázený častými genetickými změnami. Biochemické změny, jež jsou podstatou epigenetických procesů, zahrnují metylace DNA a posttranslační modifikace proteinů. Nejvíce studovanou epigenetickou modifikací je metylace DNA, ale v rámci komplexního přístupu v diagnostice a léčbě tohoto onemocnění se zdá být prospěšnější poznání vzájemných interakcí a návazností mezi metylacemi DNA a jinými epigenetickými změnami, jako jsou miRNA nebo metylace histonových proteinů. V našem návrhu bychom se chtěli zaměřit na přínos uvedených změn k hlubšímu pochopení patogeneze onemocnění a také na detekci metylace v důsledku vazby transkripčních faktorů na specifická místa DNA v promotorových oblastech prognosticky významných tumor-supresorových genů u mnohočetného myelomu.
- Keywords
- DNA methylation, hydroxymetylace, hydroxymethylation, mnohočetný myelom, multiple myeloma, metylace DNA, modifikace histonů, Metyltransferazy DNA, miRNA-29, Demetylace DNA, geny TET, DNA methyltransferases, Histone modifications, miRNA-29, Demethylation DNA, TET gene family,
- NML Publication type
- závěrečné zprávy o řešení grantu AZV MZ ČR
Závěrečná zpráva o řešení grantu Interní grantové agentury MZ ČR
Přeruš. str. : il., tab. ; 32 cm + 1 volná příloha (Ekonomická část)
Diagnosis of fraX positive patiens among mentaly retarded ones,determination of DXS548 and FRAXAC1,cloning of PCR products,assesment of non-B structures of DNA demethylation of DNA and study of stability of hypomethylated repetition.
Odběry krve pacientů suspektních fraX, odhalení podílu fraX pozitivních v populaci mentálně postižených, stanovení (CA)n, klonování PCR produktůů a analýza lokálních struktur DNA, demetylace DNA a vliv metylace na stabilizaci expandované (CGG)n.
- MeSH
- Chromosome Fragility MeSH
- DNA analysis MeSH
- Trinucleotide Repeat Expansion MeSH
- Intellectual Disability genetics MeSH
- Mass Screening MeSH
- Polymerase Chain Reaction utilization methods MeSH
- Fragile X Syndrome MeSH
- Conspectus
- Obecná genetika. Obecná cytogenetika. Evoluce
- NML Fields
- genetika, lékařská genetika
- biologie
- NML Publication type
- závěrečné zprávy o řešení grantu IGA MZ ČR
- MeSH
- DNA Demethylation MeSH
- Embryonic and Fetal Development genetics MeSH
- Enzymes metabolism MeSH
- Epigenomics * MeSH
- Gene Expression genetics MeSH
- Genome genetics MeSH
- Histones genetics MeSH
- Ascorbic Acid * genetics metabolism MeSH
- Humans MeSH
- Neoplasms metabolism MeSH
- Ascorbic Acid Deficiency metabolism MeSH
- Aging metabolism MeSH
- Child Development MeSH
- Check Tag
- Humans MeSH
