Abstract Metastasis Associated in Colon Cancer 1 (MACC1) is a key metastatic molecule, used as a prognostic and predictive biomarker for metastasis formation and therapy outcomes. A high expression predicts poor survival and therapy resistance to common chemotherapeutics. Recently we have identified a novel transcriptional inhibitor of the MACC1 gene. This tetrazolo-pyridazine-based compound (compound 22) was discovered through a high-throughput screen (HTS) using the human MACC1 promoter coupled to a luciferase reporter gene. 1,2,3,4-tetrazolo1,5-bpyridazine-based compounds can act as effective MACC1 inhibitors in vitro by reducing MACC1-induced cancer cell motility. This translates in reduced metastasis formation in mice, and thus pose them promising candidates for anti-metastatic therapies particularly for patients with MACC1-overexpressing cancers, that are at high risk to develop metastases. To identify the mode of action, we used RNA-sequencing to reveal the gene expression changes under compound 22 treatment which displayed the TNF-α signaling via NFκB was attenuated. Subsequent gene ontology analysis of the differentially expressed genes showed changes in biological functions such as cell cycle progression and intermediate filament-based processes. These render the cells less proliferative and with more epithelial characteristics. Molecular analysis of the NFκB pathway revealed a reduced p65 and p50 activity with reduced nuclear translocation and activity on the MACC1 promoter. In silico predictions revealed p105 as a possible protein target. Further, the novel compound blocks the TNF-α induced phosphorylation of p105. Although further experimental data is needed to address the potential binding of the identified tetrazolo-pyridazine-based compound to p105, this study revealed that the NFκB signaling pathway is strongly reduced under the treatment with this novel compound. This in turn reduces the MACC1 gene expression and thereby the metastatic potential of cancer cells. Citation Format: Ulrike S. Stein. Novel MACC1 transcriptional inhibitor act via reduced NFκB signaling pathway to reduce metastasis formation abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2237.
Ulrike Stein (Fri,) studied this question.