Roscopy Core Facility is gratefully acknowledged. Conflicts of Interest: The authors
Roscopy Core Facility is gratefully acknowledged. Conflicts of Interest: The authors declare no conflict of interest. The funders had no function within the design of your study; within the collection, analyses, or interpretation of information; in the writing on the manuscript, or within the selection to publish the outcomes.Cancers 2021, 13,18 of
cancersArticleFrequent Epigenetic Inactivation of PK 11195 manufacturer DIRAS-1 and DIRAS-2 Contributes to Chemo-Resistance in GliomasTanja Rothhammer-Hampl 1 , Franziska Liesenberg 2 , Natalie Hansen 2 , Sabine Hoja 1 , Sabit Delic 1 , Guido Reifenberger 2,3 and Markus J. Riemenschneider 1, Department of Neuropathology, Regensburg University Hospital, 93053 Regensburg, Germany; [email protected] (T.R.-H.); [email protected] (S.H.); [email protected] (S.D.) Institute of Neuropathology, Health-related Faculty, University Hospital D seldorf, Heinrich Heine University, 40225 D seldorf, Germany; [email protected] (F.L.); [email protected] (N.H.); [email protected] (G.R.) German Cancer Consortium (DKTK), Partner Website Essen/D seldorf, 40225 D seldorf, Germany Correspondence: [email protected]; Tel.: 49-941-Citation: Rothhammer-Hampl, T.; Liesenberg, F.; Hansen, N.; Hoja, S.; Delic, S.; Reifenberger, G.; Riemenschneider, M.J. Frequent Epigenetic Inactivation of DIRAS-1 and DIRAS-2 Contributes to Chemo-Resistance in Gliomas. Cancers 2021, 13, 5113. https:// doi.org/10.3390/cancers13205113 Academic Editor: Chiara Laezza Received: 25 August 2021 Accepted: eight October 2021 Published: 12 OctoberSimple Summary: We investigated the genes DIRAS-1 and DIRAS-2 in terms of their regulation and functional relevance in brain tumors (gliomas). We located that in a majority of individuals the expression of both genes is strongly downregulated on the mRNA level when comparing tumors with healthful brain tissue. We could show that epigenetic mechanisms account for this downregulation. Both promoter methylation and histone modifications are accountable. We performed experiments in tumor tissues (direct bisulfite sequencing and chromatin-immunoprecipitation) and we treated glioblastoma cell lines within a strategy to overcome epigenetic inactivation of both genes. When genes were re-expressed, the tumor cells turned out additional sensitive to alkylating chemotherapeutic agents like Lomustin. Modifications in intracellular pathways associated to p53-mediated DNA harm response might explain for this observation. Abstract: We previously reported that DIRAS-3 is regularly inactivated in oligodendrogliomas as a consequence of promoter hypermethylation and loss in the chromosomal arm 1p. DIRAS-3 inactivation was connected with improved general AZD4625 Data Sheet survival. Consequently, we now investigated regulation and function of its members of the family DIRAS-1 and DIRAS-2. We discovered that DIRAS-1 was strongly downregulated in 65 and DIRAS-2 in one hundred of analyzed glioma samples compared to non-neoplastic brain tissue (NNB). In addition, a significant down-regulation of DIRAS-1 and -2 was detected in glioma data obtained from the TCGA database. Mutational analyses didn’t reveal any inactivating mutations in the DIRAS-1 and -2 coding regions. Evaluation in the DIRAS-1 and -2 promoter methylation status showed substantially larger methylation in IDH-mutant astrocytic and IDH-mutant and 1p/19q-codeleted oligodendroglial tumors in comparison with NNB. Remedy of U251MG and Hs683 glioblastoma cells lines with 5-azacytidine led to significant re-expression of DIRAS-1 and -2. For IDH.