Abstract Disclosure: R. Stojchevski: None. A. Lavi: None. J. Bogdanov: None. N. Hadzi-Petrushev: None. M. Mladenov: None. L. Poretsky: None. D.B. Avtanski: None. The synthesis of monocarbonyl analogs of curcumin (MACs) presents a solution to the challenges posed by curcumin, a natural polyphenol extracted from the roots of the turmeric plant (Curcuma longa), which is known for its antioxidant and anti-inflammatory properties. The limitations of curcumin, including poor stability, low bioavailability, and rapid metabolism, hinder its application, and MACs, designed without a β-diketone moiety, address these drawbacks and exhibit enhanced stability and bioavailability. This study aimed to assess the effects of two monocarbonyl analogs of curcumin, (2E,6E)-2,6-bis[(2-trifluoromethyl)benzylidene]cyclohexanone (C66) and (2E,6E)-2,6-bis(2-bromobenzylidene)cyclohexanone (B2BrBC), on epithelial-to-mesenchymal transition (EMT) in MCF-7 breast cancer cells using western blot analysis. Our previous findings indicated that these analogs can potentially affect EMT by modulating the epithelial and mesenchymal gene expression. MCF-7 cells were cultured in complete medium supplemented with EMT-inducing factors for two days, followed by C66 and B2BrBC administration (100 µM) for three additional days. After the experiments, proteins were extracted, and western blot analyses were performed to measure the expression levels of various epithelial and mesenchymal markers (E-cadherin, N-cadherin, SNAI1, and Claudin-1). The results revealed that both C66 and B2BrBC increased the protein levels of the epithelial marker E-cadherin and suppressed those of the mesenchymal marker N-cadherin. Moreover, C66 and B2BrBC decreased the protein expression of the transcription factor SNAI1 and transmembrane protein Claudin-1. Between the two MACs, B2BrBC showed a more pronounced effect on N-cadherin expression, while C66 was more potent in suppressing SNAI1 protein expression. Our findings demonstrate that C66 and B2BrBC counteract EMT, contributing to the potential therapeutic applications of MACs in managing breast cancer progression. Presentation: 6/3/2024