EZH2 endorses cell plasticity to non-small cell lung cancer cells facilitating mesenchymal to epithelial transition and tumour colonization

CGL was funded by the Consejería de Salud y Familias, Junta de Andalucía (RH-0139-2020) and SG-P is funded by Instituto de Salud Carlos III (CP19/00029, PI15/00336, PI19/01533). JAM is supported by RTI2018.101309B-C22 funded by MCIN/AEI/10.13039/501100011033/FEDER “Una manera de hacer Europa” and by the Chair “Doctors Galera-Requena in cancer stem cell research”. PCS is funded by Ministerio de Ciencia e Innovación (grant PID2020-119032RB-I00) and FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades (grants P20_00335 and B‐CTS‐40‐UGR20). The Landeira lab is supported by the Spanish ministry of science and innovation (PID2019-108108-100, EUR2021-122005), the Andalusian regional government (PC-0246-2017, PIER-0211-2019, PY20_00681) and the University of Granada (A-BIO-6-UGR20) grants.Reversible transition between the epithelial and mesenchymal states are key aspects of carcinoma cell dissemination and the metastatic disease, and thus, characterizing the molecular basis of the epithelial to mesenchymal transition (EMT) is crucial to find druggable targets and more effective therapeutic approaches in cancer. Emerging studies suggest that epigenetic regulators might endorse cancer cells with the cell plasticity required to conduct dynamic changes in cell state during EMT. However, epigenetic mechanisms involved remain mostly unknown. Polycomb Repressive Complexes (PRCs) proteins are well-established epigenetic regulators of development and stem cell differentiation, but their role in different cancer systems is inconsistent and sometimes paradoxical. In this study, we have analysed the role of the PRC2 protein EZH2 in lung carcinoma cells. We found that besides its described role in CDKN2A-dependent cell proliferation, EZH2 upholds the epithelial state of cancer cells by repressing the transcription of hundreds of mesenchymal genes. Chemical inhibition or genetic removal of EZH2 promotes the residence of cancer cells in the mesenchymal state during reversible epithelial–mesenchymal transition. In fitting, analysis of human patient samples and tumour xenograft models indicate that EZH2 is required to efficiently repress mesenchymal genes and facilitate tumour colonization in vivo. Overall, this study discloses a novel role of PRC2 as a master regulator of EMT in carcinoma cells. This finding has important implications for the design of therapies based on EZH2 inhibitors in human cancer patients.Junta de Andalucía (RH-0139-2020)Instituto de Salud Carlos III (CP19/00029, PI15/00336, PI19/01533)MCIN/AEI/10.13039/501100011033/FEDER “Una manera de hacer Europa” RTI2018.101309B-C22Chair “Doctors Galera-Requena in cancer stem cell research”Ministerio de Ciencia e Innovación (grant PID2020-119032RB-I00)FEDER/Junta de Andalucía-Consejería de Transformación Económica, Industria, Conocimiento y Universidades (grants P20_00335 and B‐CTS‐40‐UGR20)Spanish ministry of science and innovation (PID2019-108108-100, EUR2021-122005)Andalusian regional government (PC-0246-2017, PIER-0211-2019, PY20_00681)University of Granada (A-BIO-6-UGR20

The molecular basis of cell memory in mammals: The epigenetic cycle

Cell memory refers to the capacity of cells to maintain their gene expression program once the initiating environmental signal has ceased. This exceptional feature is key during the formation of mammalian organisms, and it is believed to be in part mediated by epigenetic factors that can endorse cells with the landmarks required to maintain transcriptional programs upon cell duplication. Here, we review current literature analyzing the molecular basis of epigenetic memory in mammals, with a focus on the mechanisms by which transcriptionally repressive chromatin modifications such as methylation of DNA and histone H3 are propagated through mitotic cell divisions. The emerging picture suggests that cellular memory is supported by an epigenetic cycle in which reversible activities carried out by epigenetic regulators in coordination with cell cycle transition create a multiphasic system that can accommodate both maintenance of cell identity and cell differentiation in proliferating stem cell populations.Grant (EUR2021-122005) funded by MCIN/AEI/10.13039/501100011033Spanish Ministry of Science and Innovation (PID2022-137060NB-I00 and PID2019-108108-100)Instituto de Salud Carlos III (IHRC22/00007)Andalusian regional government (PC-0246-2017, PIER-0211-2019, and PY20_00681)University of Granada (A-BIO-6-UGR20