Abstract 275: Increased expression levels of <i>KISS1</i> in IDCC breast cancer induced by melatonin treatment

Abstract Introduction: Tumor suppressors encode proteins commonly expressed in non-cancer cells that avoid abnormal events that culminate to neoplasms development. In a deregulated expression case, they are useful as biomarkers for pathological stages or tumor progression. KISS1 (KiSS-1 metastasis suppressor), is a known metastatic suppressor and its expression is commonly downregulated in the metastatic tumors of various origins, including breast cancer. In this context, some researches showed that melatonin (Mel) can improve survival rates, suggesting that its application may be a tool for therapeutic use in some breast tumors. Thereby, we aimed to identify mRNA levels of KISS1 in invasive ductal carcinoma cells (IDCC) with metastasis in pleural effusion (MCF7) treated with Mel and compare with MCF7 non-treated cells (CC). Methods: MCF7 (ER+) cell line was cultured with RPMI 1640 (Sigma-Aldrich, Germany), with 10% fetal bovine serum (FBS - Gibco, USA) treated with activated charcoal, inactivated, sodium bicarbonate, pyruvic acid and antibiotics as recommended by ATCC and subsequently treated with 3000 μM Mel. After treatment the RNA was extracted using mirVana miRNA Isolation Kit (Ambion, USA) and then, purity and concentration of total RNA were accessed. The Reverse transcription synthesis was performed using High-Capacity cDNA Reverse Transcription Kit (ThermoFisher Scientific, Lithuania). Expression profile of 91 mRNA, including KISS1 and, 5 housekeeping mRNAs was performed by TaqMan Array Plates using Real-Time PCR (Applied Biosystems, USA). Data analysis was obtained by ExpressionSuit Software v1.3 (ThermoFisher Scientific). Results: The concentration of melatonin tested in MCF7 cells (ER+) from metastasis showed, a significant increase of mRNA KISS1 expression levels when compared to the levels presented in MCF7 cells that did not receive melatonin treatment (control cell - CC). Conclusion: Melatonin treatment was able to increase the expression of KISS1 in MCF7 cells, indicating that its use may bring benefits associated to an improved prognosis for similar tumors. Further studies are ongoing to confirm and expand our results. Citation Format: Kelly P. Ferreira, Bruna C. Almeida, Edmund C. Baracat, Katia C. Carvalho. Increased expression levels of KISS1 in IDCC breast cancer induced by melatonin treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 275.