The methionine cycle and its cancer implications.

The essential amino acid methionine is a crucial regulator of sulfur metabolism in a variety of interconnected biochemical pathways. The methionine cycle is intricately linked to the folate cycle, forming the one-carbon metabolism, a crucial regulator of S-adenosylmethionine, SAM. Recent work highlights methionine's critical role in tumor growth and progression, maintaining polyamine synthesis, and playing a crucial role in the regulation of SAM both in altered chromatin states, depending on p53 status, as well as facilitating m6A methylation of NR4A2 mRNA, hence regulating proliferation in esophageal carcinoma. Accordingly, Celecoxib, a specific NR4A2 inhibitor, is a potentially powerful inhibitor of tumor growth at least in this specific model. Additionally, formaldehyde, from endogenous or exogenous sources, can directly regulate both SAM steady-state-levels and the one-carbon metabolism, with relevant implication in cancer progression. These recent scientific advancements have provided a deeper understanding of the molecular mechanisms involved in cancer development, and its potential therapeutic regulation.