Efficient identification of new small molecules targeting succinate dehydrogenase in non-small cell lung cancer.

Background: Lung cancer treatment efficacy remains a challenge due to limited therapeutic targets. Succinate dehydrogenase (SDH) enzyme, a crucial enzyme linking the citric acid cycle and the electron transport chain, is implicated in cancer metabolism. While existing compounds target metabolic diseases in vitro, SDH-targeted therapy for lung cancer remains elusive.

Methods: We assessed SDH expression levels in non-small cell lung (NSCLC) tissues and cell lines. Leveraging AtomNet® technology for compound identification, coupled with mitochondria- and cell-based enzyme activity assays, we discovered new SDH inhibitors. Using 2D monolayer, 3D organoid culture, and assays for cell viability, migration, mitochondrial reactive oxygen species, oxygen consumption rate, succinate accumulation, and apoptosis, we elucidated their mechanism targeting lung malignancy.

Results: SDH subunits were found to be overexpressed in NSCLC tissues compared to tumor-adjacent normal tissues. Two new SDH inhibitors were identified from 96 predicted candidates. Cellular thermal shift assay confirmed direct binding of these small molecules to SDH subunits in lung cancer cells. Mechanistically, treatment increased cellular and mitochondrial reactive oxygen species, succinate accumulation, and induced apoptosis by damaging mitochondria and DNA, while modulating SDH protein expression. Functionally, these molecules reduced growth, migration, and 3D organoid formation in lung cancer cell lines in vitro, both short and long term.

Conclusions: Our SDH inhibitors halt tumor growth and migration by targeting key substrate binding sites, showing superior efficacy over existing small molecule antagonists. They also modulate SDH protein expression, suggesting a promising dual-targeting strategy for cancer therapy. This study sheds light on SDH function in cancer-related metabolic dysfunction and underscores the potential of SDH modulation as a therapeutic strategy for lung cancer and beyond.