THU553 Anti-tumor Effect Of Rosiglitazone Via Upregulating 15-PDGH In Prolactin Secreting Adenoma

Disclosure: C. Kang: None. J. Oh: None. E. Wang: None. S. Lee: None. J. Nam: None. J. Hong: None. E. Lee: None. C. Ku: None. Background: Rosiglitazone, a synthetic peroxisome proliferator-activated receptor γ (PPAR γ) ligand, are used to treat type II diabetes. Over the last few years, PPAR γ has received much attention for its ability to exert variable tumors. Objective: The aim of this study is to investigate the anti-tumor effect of rosiglitazone on prolactin secreting pituitary adenomas and its mechanism. Materials & Methods: Lactotroph cell line (GH4, MMQ) were treated with Phosphate-buffered saline (PBS) or rosiglitazone. In vitro analysis such as qPCR, immunoblot, prolactin (PRL) ELISA, Cell proliferation assay, and Fluorescence-activating cell sorting (FACS) analysis were performed to examine the effect of rosiglitazone on Lactotroph cell lines. Result: To investigate the direct effect of rosiglitazone on PRL secretion of the pituitary adenomas, GH4 and MMQ cells were treated with rosiglitazone 1, 5, 10, 50 μM for 72 hr. Both PRL mRNA and secretion levels were significantly decreased by rosiglitazone in a dose-dependent manner. In previous studies, 15-PDGH has been implicated as a tumor suppressor gene with the property that inhibits the tumor growth. Interestingly, 5 μM rosiglitazone upregulated the mRNA and protein levels of 15-PDGH in both GH4 (4.73-fold) and MMQ (4.04-fold) cells. Next, we investigated whether rosiglitazone had any effects on the proliferation of prolactinoma cells. Proliferation of the GH4 and MMQ cells were significantly decreased by rosiglitazone in a dose-dependent manner after treatment. Rosiglitazone potently induced cell cycle arrest in sub-G1inGH4 and MMQ cells. Furthermore, rosiglitazone treatment significantly increased both early (2.31-fold) and late apoptosis (1.9-fold) of GH4 and MMQ cells. Conclusion: These results collectively position 15-PDGH as a potential new therapeutic target for prolactinomas and implicate rosiglitazone as a possible alternative pharmacological approach for prolactinomas. Presentation: Thursday, June 15, 2023