Abstract 530: The effect of cardamonin on PD-L1 expression in triple-negative breast cancer cells

Abstract

Abstract Triple-negative breast cancer (TNBC) accounts for about 10% of all breast cancers and does not express estrogen, progesterone, or HER2 receptors. It has an aggressive nature, it is highly metastatic, and because of the lack of therapies, it continues to be a challenge. These cancer cells employ mechanisms to escape the immune system that induce the upregulation of PD-L1 expression, a ligand encoded by the CD274 gene. Because cancer cells tend to produce higher levels of PD-L1 compared to normal cells, therapies that inhibit PD-L1 may be helpful. Evidence also shows that high levels of oxidative stress and inflammation may participate in both the initiation and progression of cancer. Cardamonin, an aromatic enone flavonoid, has displayed an array of pharmacological activities, including modulation of different signaling molecules involved in the development and progression of cancer. This work investigated the cardamonin’s ability to modulate PD-L1 expression and NF-KB in genetically distinct MDA-MB-231 (Caucasian) and MDA-MB-468 (African American) TNBC cell lines. The methodology included cytotoxic assays, ELISA, Real Time-Polymerase Chain Reaction (RT-PCR) assays, and Wes analysis. The results showed that cardamonin treatment caused a dose-dependent decrease in cell viability in both cell lines, ranging from 3.12 µM to 200 µM. The RT-PCR and ELISA data showed that even though IFN-γ stimulated MDA-MB-231 cells showed a higher expression of PD-L1, cardamonin reduced mRNA and protein expression of PD-L1 in both cell lines. As a possible molecular mechanism for PD-L1 inhibition, cardamonin modulated MUC-1, STAT3, and JAK, which are genes that activate the PD1/PD-L1 mechanism. Moreover, data also show that cardamonin modulated NF-KB1 and NF-KB2 genes involved in activating NF-KB signaling. NF-KB is a transcription factor of inflammation and immunity, emerging as a key positive regulator of PD-L1 expression in cancer. Therefore, cardamonin may have the potential utilization as a checkpoint inhibitor that acts by blocking PD-L1 protein, allowing the immune system to recognize and attack the TNBC cancer cells, providing a novel cancer therapy. (Supported by a grant from NIH-NIMHD U54 MD 007582) Citation Format: Patricia Mendonca, Bhonessa Kirpal, Sukhmandeep Kaur, Karam F. A. Soliman. The effect of cardamonin on PD-L1 expression in triple-negative breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 530.