Cellular process discovery may lead to new cancer treatments
Ed Schmidt, a molecular geneticist at Montana State University, has discovered a backup cellular system that produces the amino acid cysteine when primary disulfide reductase systems fail, according to a study published May 21 in Nature Chemical Biology. This process involves severing a carbon-sulfur bond in cystine, providing a survival mechanism that may allow cancer cells to resist chemotherapy and radiation.
How does the backup cysteine production system work?
Mammalian cells typically obtain cysteine by chemically splitting an oxidized form called cystine through a disulfide reductase system. Schmidt’s research reveals a previously unknown alternative: when the primary system fails, a backup system severs an adjacent carbon-sulfur bond in the cystine to release the necessary cysteine.
Cysteine is essential for cell survival. It allows cells to build proteins and defend against damage. According to Schmidt, the amino acid also enables the formation of disulfide bonds, which stabilize proteins and maintain the cell’s three-dimensional shape.
Why does this discovery impact cancer treatment?
The same mechanism that protects healthy cells from electrophilic toxins—organic molecules used by some organisms to kill others—likely protects cancer cells from medical intervention. Schmidt stated that this pathway probably helps cancer cells survive exposure to immune therapies, radiation, and chemotherapies.
Because this backup system acts as a defense mechanism, Schmidt suggests that disabling it could make tumors more vulnerable. By precisely targeting this pathway, clinicians might increase the effectiveness of existing cancer therapies.
How was this “impossible” cellular process discovered?
The discovery resulted from a nine-year project that began with a contradiction in established science. In 2014, Schmidt observed a colony of mice surviving despite lacking the disulfide reductase system. At the time, scientific consensus held that no living cell could survive without this system.
Schmidt had genetically engineered these mice to lack specific disulfide reductases in the liver. After seeing physiological responses that contradicted existing theories, he spent seven years investigating the mechanism. He partnered with Peter Nagy of the Hungarian National Institute of Oncology in Budapest, who provided the analytical tools needed to identify the carbon-sulfur bond cleavage.
What are the evolutionary origins of this system?
Schmidt believes this backup system evolved in early multicellular ancestors. It likely served as a survival strategy to resist electrophilic toxins found in the environment or in the prey those organisms consumed.
Sreekala Bajwa, dean of the agricultural college at Montana State University, noted that the breakthrough redefines what scientists thought was possible regarding cellular survival and opens new avenues for global health impact.
Comparison: Primary vs. Backup Cysteine Production
| Feature | Primary System | Backup System |
|---|---|---|
| Mechanism | Disulfide reductase system | Carbon-sulfur bond cleavage |
| Status | Essential/Standard | Emergency/Backup |
| Clinical Role | General cell maintenance | Toxin and therapy resistance |
Frequently Asked Questions
What is cysteine?
Cysteine is an amino acid required by all cells to build proteins, maintain structural shape, and protect against cellular damage.
Where was this research published?
The findings were published in the scientific journal Nature Chemical Biology on May 21.
Who led the study?
The study was led by Ed Schmidt, a professor of genetics and development at Montana State University, in collaboration with Peter Nagy of the Hungarian National Institute of Oncology.
Can this lead to a cure for cancer?
While not a cure itself, the discovery identifies a specific defense mechanism in cancer cells. Disabling this system may make current therapies more effective.
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