NUMB x p53

Excessive glycogen deposition is a common feature of liver enlargement, liver adenoma, and liver cancer, yet the underlying mechanisms remain poorly understood. In this study, we found that NUMB, a well-known cell fate determinant, is downregulated in glycogen-rich adenomas and hepatocellular carcinoma (HCC). NUMB-deficient livers developed excessive glycogen accumulation and adenoma formation particularly in aged mice. Surprisingly, the Alb-Cre:Trp53^loxP/loxP liver displayed no similar defective morphology and function, although p53 is considered an important downstream target of NUMB and closely related to glucose metabolism. Instead, we observed a synergistic interaction between NUMB and p53 in regulating glycogen metabolism in HCC tissues and cell lines. Combined knockout of NUMB and p53 in mice significantly enhances glycogen accumulation and hepatomegaly, particularly when mice are subjected to a high sugar diet (HSD), leading to higher cancer incidence. Mechanistically, NUMB deficiency disrupts the PTEN-PI3K/AKT signaling pathway, promoting glycogen accumulation. Subsequently, successive glycogen deposition triggers hepatomegaly and tumorigenesis via the Hippo signaling pathway. Our results suggest that NUMB plays a crucial role in maintaining the homeostasis of glucose metabolism and suppressing the development of liver tumors associated with glycogen deposition.

NUMB is a tumor suppressor gene that functions by inhibiting the action of the NOTCH proto‐oncogene and enhancing the levels and activity of the tumor suppressor protein p53. In breast cancer (BC), NUMB loss of function (LOF), mediated by various molecular mechanisms, is a frequent and causal event. Herein, it is established that loss of NUMB protein, resulting from protein hyper‐degradation, is the prevalent mechanism of NUMB LOF in BC. Through an RNAi‐based screening, the CRL7 FBXW8 complex is identified as the E3 ligase complex responsible for NUMB hyper‐degradation in BC. Genetic and pharmacological inhibition of CRL7 FBXW8 rescues the transformation‐related phenotypes induced by NUMB LOF in BC cell lines and in patient‐derived xenografts. These effects are directly dependent on the restoration of NUMB protein levels. Thus, enhanced CRL7 FBXW8 activity, through its interference with the tumor suppressor activity of NUMB, is a causal alteration in BC, suggesting it as a potential therapeutic target for precision medicine.

Developing and identifying effective medications and targets for treating hepatic fibrosis is an urgent priority. Our previous research demonstrated the efficacy of artesunate (ART) in alleviating liver fibrosis by eliminating activated hepatic stellate cells (HSCs). However, the underlying mechanism remains unclear despite these findings. Notably, endocytic adaptor protein (NUMB) has significant implications for treating hepatic diseases, but current research primarily focuses on liver regeneration and hepatocellular carcinoma. The precise function of NUMB in liver fibrosis, particularly its ability to regulate HSCs, requires further investigation. This study aims to elucidate the role of NUMB in the anti-hepatic fibrosis action of ART in HSCs. We observed that the expression level of NUMB significantly decreased in activated HSCs compared to quiescent HSCs, exhibiting a negative correlation with the progression of liver fibrosis. Additionally, ART induced senescence in activated HSCs through the NUMB/P53 tumor suppressor (P53) axis. We identified NUMB as a crucial regulator of senescence in activated HSCs and as a mediator of ART in determining cell fate. This research examines the specific target of ART in eliminating activated HSCs, providing both theoretical and experimental evidence for the treatment of liver fibrosis.