Mossmann, D. | bioRxiv Science

bioRxiv2026

Antizyme regulates polyamine uptake via ATP13A3

Intracellular polyamine levels are tightly regulated and frequently elevated in cancer. While the regulation of polyamine synthesis is well characterized, the regulation of polyamine uptake is poorly understood. Here we identify ATP13A3 as a plasma membrane polyamine transporter. An increase in intracellular polyamine levels, due to polyamine supplementation or induction of polyamine synthesis, causes rapid internalization of the transporter and inhibition of polyamine uptake. Mechanistically, increased polyamine concentrations lead to expression of antizyme (AZ) which binds ATP13A3 and triggers its internalization. Mutations in the AZ binding site of ATP13A3 prevent AZ binding and lead to polyamine toxicity through uncontrolled polyamine influx. These findings establish ATP13A3 as a key polyamine transporter and provide a framework for targeting polyamine metabolism in cancer.

cell biology↗

bioRxiv2022

Elevated arginine levels in liver tumors promote metabolic reprogramming and tumor growth

Arginine auxotropy, due to reduced expression of urea cycle genes, is common in cancer. However, little is known about the levels of arginine in these cancers. Here, we report that arginine levels are elevated in hepatocellular carcinoma (HCC) despite reduced expression of urea cycle enzymes. Liver tumors accumulate high levels specifically of arginine via increased uptake and, more importantly, via suppression of arginine-to-polyamine conversion due to reduced arginase 1 (ARG1) and agmatinase (AGMAT) expression. Furthermore, the high levels of arginine are required for tumor growth. Mechanistically, high levels of arginine promote tumorigenesis via transcriptional regulation of metabolic genes, including upregulation of asparagine synthetase (ASNS). ASNS-derived asparagine further enhances arginine uptake, creating a positive feedback loop to sustain high arginine levels and oncogenic metabolism. Thus, arginine is a novel second messenger-like molecule that reprograms metabolism to promote tumor growth.

cancer biology↗