Neddylation pathway promotes FBXO21 degradation, stabilizing p53 and increasing p21 in lung cancer cells.

Lung cancer remains a leading cause of cancer-related mortality, with challenges in targeted therapies. The ubiquitin-proteasome system, particularly the SCF E3 ligase complex, is crucial in regulating protein stability and function in various physiological and pathological processes, including cancer. F-box proteins, like FBXO21, are key components of SCF, determining substrate specificity. However, the precise regulatory mechanisms governing FBXO21 degradation and its role in human cancers, specifically lung cancer, have been largely unexplored, representing a significant knowledge gap. Understanding these pathways could reveal new therapeutic targets.

Researchers investigated the regulation of FBXO21 in lung cancer cells. They employed mechanistic studies to identify the E3 ligase responsible for FBXO21 degradation. Specifically, they focused on the Neddylation pathway and its associated E3 ligase, ROC1. Experiments involved assessing protein levels and ubiquitination status of FBXO21, and investigating the downstream effects of FBXO21 depletion on p53 protein stability and p21 transcriptional levels, likely using techniques such as western blot and qPCR.

The study demonstrated that the Neddylation pathway, specifically through the ROC1 E3 ligase, directly regulates the protein level of FBXO21. Mechanistic investigations confirmed that Neddylation-ROC1 targets FBXO21 for ubiquitination and subsequent degradation. This finding establishes a direct link between the Neddylation machinery and FBXO21 stability.

Crucially, depletion of FBXO21 was found to increase p53 protein stability by significantly delaying its degradation. This stabilization of p53 subsequently led to an increase in the transcriptional level of p21, a known p53 target gene involved in cell cycle arrest. These results collectively reveal a novel regulatory axis where Neddylation controls FBXO21 degradation, which in turn modulates the critical p53-p21 signaling pathway in lung cancer cells.