Researchers from the Tokyo University of Science in Japan have identified a worrying side effect associated with popular anti-aging supplements. The scientists focused their attention on polyamines—natural compounds such as spermidine and putrescine—which are widely promoted as agents for life extension and combating senescence. The findings of this investigation are detailed in the Journal of Biological Chemistry.
Polyamines are present in every living cell and play a vital part in regulating cell growth and protein synthesis. Earlier animal studies did indeed confirm that spermidine could enhance memory and increase lifespan. However, this very ability to stimulate cellular processes renders these compounds potentially hazardous in the context of oncology.
The scientists aimed to determine how polyamines affect the metabolism of cancer cells, specifically their tendency toward aerobic glycolysis—the process of consuming sugar without utilizing oxygen, which serves as the primary energy source for malignant tumors. In experiments conducted on cultures of cervical and breast cancer cells, the researchers modulated polyamine levels and monitored the response of two crucial proteins: eIF5A1 and eIF5A2.
Despite their structural similarity, these proteins fulfill different roles. The former is essential for maintaining the health of normal cells, whereas the latter is implicated in tumor development and proliferation. It was discovered that polyamines not only push cancer cells toward an actively fed state but also directly boost the production of the “harmful” protein eIF5A2. This occurs by lifting the natural “brake”—an RNA molecule dubbed miR-6514-5p, which normally suppresses the synthesis of this protein.
When the investigators removed polyamines or the eIF5A2 protein from the cells, the proliferation of the cancer cells significantly slowed down. Reintroducing spermidine restored the tumor’s capacity for expansion, thus proving the critical involvement of these compounds in the proliferation of existing cancerous cells.
One of the study’s authors, biochemist Keihan Higashi, explained that the biological effect of polyamines mediated through the eIF5A proteins differs between healthy and cancerous tissues. Normally, they support mitochondrial function, but in pathologically altered cells, they drive multiplication.
It is important to emphasize that the study does not assert that polyamines cause cancer. The focus is elsewhere: if a cancerous process has already begun in the body, malignant cells are adept at hijacking the beneficial properties of these compounds and repurposing them for their own growth. Nevertheless, identifying the precise role of the eIF5A2 protein and the regulatory molecule miR-6514-5p opens up novel therapeutic avenues. Understanding this mechanism allows for the design of drugs that could intercept the interaction between polyamines and cancer cells, thereby inhibiting tumor advancement without detrimental effects on healthy tissues.
What are polyamines?
Polyamines (spermidine, spermine, putrescine) are organic compounds found in all living cells. They are involved in cell growth, proliferation, differentiation, and apoptosis. As individuals age, the level of polyamines in the body declines, which is why artificially replenishing them is considered a potential anti-aging strategy.
Where are polyamines found?
Foods rich in polyamines include:
- Soybeans (especially fermented varieties like natto, miso)
- Mushrooms
- Wheat germ
- Pumpkin seeds
- Grapefruit
- Green peas
- Aged cheeses
What is the essence of the Japanese scientists’ discovery?
The researchers uncovered the mechanism by which cancer cells “hijack” beneficial polyamines and exploit them for growth. Two proteins play a central role: eIF5A1 (beneficial, supports healthy cells) and eIF5A2 (detrimental, linked to tumor aggressiveness). Polyamines activate the production of eIF5A2 by removing the inhibitory effect of microRNA.
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