Treatment with 1,25-dihydroxyvitamin D3 (1,25[OH]2 D3) suppresses leptin-mediated growth of ovarian cancer cells and administration of a 1,25(OH)2 D3 analogue suppresses ovarian tumour growth induced by a high-fat diet in mice, show new findings. The anti-leptin effects of 1,25(OH)2 D3 are mediated by a microRNA, miR-498, which downregulates expression of telomerase reverse transcriptase mRNA.