Treatment with 5′-aza-2-deoxycytidine restored miR-204-5p and TRPM3 expressions, suggesting that DNA methylation epigenetically silences miR-204-5p expression, as already demonstrated in papillary thyroid carcinoma [32], in cutaneous squamous cell carcinoma [53], in glioma [54] and in leukaemia [55], indicating that DNA methylation could be a common regulatory mechanism of miR-204-5p expression in cancer. The gene discussed is TRPM3; the disease is central nervous system cancer.