Aberrant DNA methylation observed in cancer can provide survival benefits to cells by silencing genes essential for anti-tumor activity. DNA-demethylating agents such as Decitabine (DAC)/Azacitidine (AZA) activate otherwise silenced tumor suppressor genes, alter immune response and epigenetically reprogram tumor cells. In this study, we show that non-cytotoxic nanomolar DAC concentrations modify the bladder cancer transcriptome to activate NOTCH1 at the mRNA and protein level, increase double-stranded RNA sensors and CK5-dependent differentiation. Importantly, DAC treatment increases ICN1 expression (the active intracellular domain of NOTCH1) significantly inhibiting cell proliferation and causing changes in cell size inducing morphological alterations reminiscent of senescence. These changes were not associated with β-galactosidase activity or increased p16 levels, but instead were associated with substantial IL-6 release. Increased IL-6 release was observed in both DAC-treated and ICN1 overexpressing cells as compared to control cells. Exogenous IL-6 expression was associated with a similar enlarged cell morphology that was rescued by the addition of a monoclonal antibody against IL-6. Treatment with DAC, overexpression with ICN1 or addition of exogenous IL-6 showed CK5 reduction, a surrogate marker of differentiation. Overall this study suggests that in MIBC cells, DNA hypomethylation increases NOTCH1 expression and IL-6 release to induce CK5-related differentiation.
Cell death & disease. 2017 Dec 14*** epublish ***
Swathi Ramakrishnan, Qiang Hu, Nithya Krishnan, Dan Wang, Evelyn Smit, Victoria Granger, Monika Rak, Kristopher Attwood, Candace Johnson, Carl Morrison, Roberto Pili, Gurkamal Chatta, Khurshid Guru, Geraldine Gueron, Lacey McNally, Jianmin Wang, Anna Woloszynska-Read
Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY, 14263, USA., Department of Bioinformatics and BioStatistics, Roswell Park Cancer Institute, Buffalo, NY, 14263, USA., Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków 31-007, Poland., Department of Medicine, Indiana University, Bloomington, IN, 47405, USA., Department of Medicine, Roswell Park Cancer Institute, Buffalo, NY, 14263, USA., Department of Biological Chemistry, School of Sciences, University of Buenos Aires, IQUIBICEN-CONICET, Intendente Guiraldes 2160, CABA, Buenos Aires 1428, Argentina., Department of Medicine, University of Louisville, Louisville, KY, 40292, USA., Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY, 14263, USA. .