{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T08:33:34Z","timestamp":1786696414086,"version":"build-2736575974"},"reference-count":48,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T00:00:00Z","timestamp":1786665600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100018990","name":"Alfaisal University","doi-asserted-by":"publisher","award":["IRG# 25345"],"award-info":[{"award-number":["IRG# 25345"]}],"id":[{"id":"10.13039\/501100018990","id-type":"DOI","asserted-by":"publisher"}]},{"award":["IRG# 25345"],"award-info":[{"award-number":["IRG# 25345"]}],"id":[{"id":"https:\/\/ror.org\/00cdrtq48","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Cancers"],"abstract":"<jats:p>Background\/Objectives: Glioblastoma (GBM) is the most lethal primary brain malignancy in adults, with a median overall survival of approximately 15 months. Temozolomide (TMZ) resistance develops in virtually all patients, and no second-line regimen has improved outcomes over the past two decades. The DNA methyltransferase inhibitor decitabine (DAC) has attracted interest as a chemosensitizer, but whether it directly reverses the TMZ-resistance transcriptome or operates through distinct, complementary mechanisms has not been tested at multi-omics resolution. Methods: We performed an integrative six-layer multi-omics analysis across five public GEO datasets (bulk RNA-seq, EPIC 850K methylation, and 21,676 single cells) re-purposed from studies conducted for unrelated aims, formally tested DAC-mediated reversal of the TMZ-resistance transcriptome across 11,707 genes, mapped pharmacogenomic targets with DGIdb v5, and built an exploratory, hypothesis-generating 11-gene prognostic model internally validated in TCGA-GBM (n = 166) and externally tested in the independent CPTAC-GBM cohort (n = 96). Results: DAC reprogrammed transcription across 1114\u20131882 differentially expressed genes per cohort and reactivated 146 direct epigenetic targets, identifying INPP5D\/SHIP1 as the top-ranked direct epigenetic-reactivation target. Genome-wide reversal analysis across 11,707 co-detected genes showed a negligible effect (Spearman \u03c1 = 0.073), but single-cell analysis revealed significant per-cell attenuation of MES-like and stem-like programs (\u0394 = \u22120.071 and \u22120.135, respectively; both p &lt; 0.001). The 11-gene risk model achieved a Harrell\u2019s C-index of 0.706 (apparent); after correcting for the two-stage gene selection with a full-pipeline bootstrap, the optimism-corrected C-index was 0.63, and external validation in an independent cohort (CPTAC-GBM, n = 96) showed only near-chance discrimination (C-index 0.55), indicating that the signature does not generalize and is exploratory. Pharmacogenomic mapping yielded 734 unique therapeutic agents (230 FDA-approved) across 69 druggable targets after excluding AR. Most of these agents are not GBM-directed, so this catalog-level mapping is hypothesis-generating rather than a set of therapeutic recommendations. Conclusions: DAC does not broadly reverse the TMZ-resistant transcriptome but acts through three complementary mechanisms: epigenetic reactivation of INPP5D\/SHIP1, cancer-testis-antigen and type I interferon induction, and per-cell attenuation of mesenchymal\u2013stem-like transcriptional intensity, supporting hypotheses for rationally designed DAC-based combination therapy in TMZ-resistant GBM.<\/jats:p>","DOI":"10.3390\/cancers18162616","type":"journal-article","created":{"date-parts":[[2026,8,14]],"date-time":"2026-08-14T08:08:29Z","timestamp":1786694909000},"page":"2616","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Decitabine Reprograms Temozolomide-Resistant Glioblastoma Through Epigenetic Reactivation and Mesenchymal Attenuation: A Multi-Omics Study"],"prefix":"10.3390","volume":"18","author":[{"given":"Itika","family":"Arora","sequence":"first","affiliation":[{"name":"College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shamsa Hilal","family":"Saleh","sequence":"additional","affiliation":[{"name":"College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arshiya","family":"Akbar","sequence":"additional","affiliation":[{"name":"College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fareeha","family":"Arshad","sequence":"additional","affiliation":[{"name":"College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-1159-4573","authenticated-orcid":false,"given":"Volodymyr","family":"Mavrych","sequence":"additional","affiliation":[{"name":"College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-9496-9754","authenticated-orcid":false,"given":"Olena","family":"Bolgova","sequence":"additional","affiliation":[{"name":"College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3521-217X","authenticated-orcid":false,"given":"Faisal Abdulhameed","family":"Farrash","sequence":"additional","affiliation":[{"name":"King Faisal Specialist Hospital and Research Centre (KFSHRC), Riyadh 12713, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ahmed","family":"Abu-Zaid","sequence":"additional","affiliation":[{"name":"College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6125-3309","authenticated-orcid":false,"given":"Andleeb","family":"Khan","sequence":"additional","affiliation":[{"name":"Department of Biosciences, Faculty of Science, Integral University, Lucknow 226026, India"},{"name":"Stem Cell Biology Lab, Integral Center of Excellence for Interdisciplinary Research-4 (ICEIR-12), Integral University, Lucknow 226026, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sheikh","family":"Muskan","sequence":"additional","affiliation":[{"name":"Department of Biosciences, Faculty of Science, Integral University, Lucknow 226026, India"},{"name":"Stem Cell Biology Lab, Integral Center of Excellence for Interdisciplinary Research-4 (ICEIR-12), Integral University, Lucknow 226026, India"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohammed Imran","family":"Khan","sequence":"additional","affiliation":[{"name":"King Faisal Specialist Hospital and Research Centre (KFSHRC), Jeddah 23433, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7536-910X","authenticated-orcid":false,"given":"Ahmed","family":"Yaqinuddin","sequence":"additional","affiliation":[{"name":"College of Medicine, Alfaisal University, Riyadh 11533, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Oike, T., Suzuki, Y., Sugawara, K., Shirai, K., Noda, S.E., Tamaki, T., Nagaishi, M., Yokoo, H., Nakazato, Y., and Nakano, T. 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