Polyamines are small molecules found naturally in every living cell, where they play a central role in essential biological functions such as cell growth and specialization. In recent years, these compounds, particularly spermidine, have attracted widespread attention in the longevity field. Spermidine is now marketed as a dietary supplement and is also found in foods like wheat germ, soybeans, mushrooms, and aged cheese, with some studies suggesting it may act as a “geroprotector” that supports healthy aging and potentially extends lifespan.
Research indicates that polyamines can stimulate protective cellular processes such as autophagy, the internal recycling system that clears damaged components and helps maintain cellular health. This beneficial effect largely depends on a protein called eukaryotic translation initiation factor 5A (eIF5A1), which helps regulate protein synthesis and mitochondrial function.
However, this promising anti-aging potential comes with a troubling contradiction. Elevated levels of polyamines are consistently observed in many types of cancer, where they are associated with rapid cell proliferation and aggressive tumor growth. This paradox has raised important questions about how the same molecules linked to longevity may also contribute to cancer progression under certain conditions.
The Polyamine Paradox in Cancer
Although polyamines are clearly associated with cancer, the molecular details of how they actively drive tumor development have remained uncertain. Cancer cells are known to rewire their metabolism. For example, they depend heavily on aerobic glycolysis to generate energy. However, the specific role that polyamines play in reshaping these metabolic pathways has not been fully explained.
There is another layer of complexity. While eIF5A1 has well documented functions in normal cells, a closely related protein called eIF5A2 has been implicated in cancer development. The two proteins share 84% of their amino acid sequence. Despite this similarity, their biological effects appear to differ dramatically.
