BUSCADOR RECOLECTA

[Background]: Promoter hypermethylation of tumour suppressor genes is frequently observed during the malignant transformation of colorectal cancer (CRC). However, whether this epigenetic mechanism is functional in cancer or is a mere consequence of the carcinogenic process remains to be elucidated., [Results]: In this work, we performed an integrative multi-omic approach to identify gene candidates with strong correlations between DNA methylation and gene expression in human CRC samples and a set of 8 colon cancer cell lines. As a proof of concept, we combined recent CRISPR-Cas9 epigenome editing tools (dCas9-TET1, dCas9-TET-IM) with a customized arrayed gRNA library to modulate the DNA methylation status of 56 promoters previously linked with strong epigenetic repression in CRC, and we monitored the potential functional consequences of this DNA methylation loss by means of a high-content cell proliferation screen. Overall, the epigenetic modulation of most of these DNA methylated regions had a mild impact on the reactivation of gene expression and on the viability of cancer cells. Interestingly, we found that epigenetic reactivation of RSPO2 in the tumour context was associated with a significant impairment in cell proliferation in p53-/- cancer cell lines, and further validation with human samples demonstrated that the epigenetic silencing of RSPO2 is a mid-late event in the adenoma to carcinoma sequence., [Conclusions]: These results highlight the potential role of DNA methylation as a driver mechanism of CRC and paves the way for the identification of novel therapeutic windows based on the epigenetic reactivation of certain tumour suppressor genes., This work was supported by Health Institute Carlos III (Plan Nacional de I + D + I) co-funding FEDER (PI18/01527 and PI21/01067 to M.F.F. and A.F.F.; COV00624 to J.R.T. and M.F.F.), the Spanish Association Against Cancer (PROYE18061FERN to M.F.F.), the Asturias Government (PCTI) co-funding 2018-2023/FEDER (IDI/2018/146 and IDI/2021/000077 to M.F.F.), The Junta de Andalucía co-funding FEDER (PY20_00051 to T.R.-A.), ISPA-Jannsen (2021-048-INTRAMURAL NOV-TEVAR to J.R.T.) and the European Commission NextGenerationEU, through CSIC’s Global Health Platform (PTI Salud Global) and the Spanish Ministry of Science and Innovation through the Recovery, Transformation and Resilience Plan (SGL2021-03-39 and SGL2021-03-040). J.R.T. is supported by the Spanish Ministry of Science and Innovation (IJC2018-036825-I and RYC2021-031799-I). A.P. is supported by the ISCIII (FI19/00085). J.G.V. is supported by the Spanish Ministry of Universities (FPU20/04659). R.F.P. (BP17-114) and P.S.M. (BP17-165) are supported by the Severo Ochoa program. R.G.U. is supported by the Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER). J.J.A.L. is supported by the AECC fellowship (PRDAS21642ALBA). A.R. is supported by CSIC (SOLAUT_00038505 SGL2103040)., Peer reviewed