Preclinical evaluation of pharmacological inhibition of SIRT1 on the growth of tumoral and metastatic granulosa cells

Abstract Background Clinical management of patients with recurrent ovarian granulosa cell tumor (GCT) remains poor. Sirtuin-1 (SIRT1), a deacetylase enzyme involved in the regulation of tumor growth and metastasis, may represent a therapeutic target due to the availability of selective pharmacological inhibitors with minimal toxicity. Methods We assessed the possible overexpression of SIRT1 during tumorigenesis by Western blot and immunohistochemistry. We tested the effects of SIRT1 inhibition by EX-527 on growth, proliferation, death, migration and gene expression by RNA sequencing and RT-qPCR in vitro on three GCT cell lines (AT29, KGN, COV434). Tumor growth in response to EX-527 treatment was examined in nude mice carrying subcutaneous GCT cell grafts using an electronic caliper and in GCT of AT83 mice by 3D ultrasound imaging system. Results SIRT1 abundance increased during tumorigenesis. In vitro treatment with EX-527 efficiently reduced cell growth, either by inducing apoptosis or by inhibiting proliferation. EX-527 induced alterations in pathways driven by mTOR, Myc and E2F, and in pathways controlling cell metabolism and oxidative stress. The administration of this treatment for 4 weeks efficiently reduced tumor progression in vivo . Conclusions Our study reveals a new therapeutic potential of SIRT1 targeting as a treatment option for patients with recurrent GCT.