Abstract 6683: Melatonin and 17β-estradiol suppress TGFB1 and TGFBR2 in IDCs cells by target miR-93-5p

Abstract miR-93-5p exerts an oncogenic effect in a tissue-specific mode, and its activity is related to cancer progression and development. In breast cancer cells, miR-93 overexpression was associated with proliferation, invasion, migration, and metastasis. In addition, it targets TGFB1 and TGFBR2 genes, which are directly involved in mammary development. Activated TGFB1 is able to directly bind the TGFBR2 promoting the cascade of signaling. TGFB1 modulates many cellular processes. However, changes in its expression may show a controversial role, both inhibiting the development of early-stage lesions (during carcinoma initiation and progression) and participating in invasion and metastasis (in the late stages of tumor progression). It is known that epigenetics events can silencing TGFB1 pathway signaling. In this context, melatonin (Mel) has gained notoriety due to its oncostatic activities and mainly to modulate miRNAs. Additionally, estrogen signaling is often associated with the onset of breast cancer and directly interacts with TGFBR2. Our goal was to evaluate the effects of Mel and 17β-estradiol (E2) treatments in invasive ductal carcinoma cells (IDC) and to assess the expression of miR-93 and its target, TGFB1 and TGFBR2. IDC cells (MCF7 (ER+) and MDA-MB231 (triple-negative) were treated with 3000 µM Mel and 100 nM E2 isolated, and the two drugs were combined (M+E2), with daily replenishment. RNA was extracted and reverse transcription synthesis was performed. RT-PCR was carried out for miR-93, TGFB1 and TGFBR2 detection. Relative quantification was determined with ExpressionSuite Software v1.3. ER-positive IDC cells showed significant suppression of miR-93 expression with Mel (Fold: 0.494) and M+E2 (Fold: 0.488) treatments, compared to control. In addition, miR-93 expression was significantly lower with M+E2 treatment compared to E2. Lower expression of miR-93 leads to an increase of TFGB1, after the Mel (Fold: 2.607) and M+E2 (Fold: 3.433) treatments, related to control and E2 treatment. This same effect was observed in TGFBR2 expression, in which the inhibition of miR-93 promoted the expression of TGFBR2 after Mel (Fold: 2.551) and M+E2 (Fold: 2.988) treatments. In triple-negative IDC cells, lower expression of miR-93 was observed in Mel (Fold: 0.868), M+E2 (Fold: 0.814), and E2 (Fold: 0.780) treatments. Suppression of miR-93 after Mel and M+E2 treatments, increased TGFB1 expression by more than seven times (Mel Fold: 7.068, and M+E2 Fold: 7.342). However, even though E2 treatment also decreased the expression of miR-93, the expression of TGFB1 did not show significant changes. In addition, TGFBR2 also presented great expression with inhibition of miR-93, after Mel (Fold: 3.005) and M+E2 (Fold: 2.723) treatments. Overall, our findings provided evidence for the significant role of miR-93 in regulating the TGFB cascade and also introduced Mel as a new therapeutic agent for targeting oncogenic miRNAs in IDC cells. Supported by: FAPESP 2022/04174-2 and 2018/24224-9. Citation Format: Bruna Cristine De Almeida, Kelly Pedrozo Ferreira, José Maria Soares-Júnior, Juciara Costa Silva, Katia Candido Carvalho, Edmund Chada Baracat. Melatonin and 17β-estradiol suppress TGFB1 and TGFBR2 in IDCs cells by target miR-93-5p [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 6683.