[Reading Science] Cause of 'Spinal Metastasis' in Terminal Cancer Patients Identified

US Research Team Discovers 'Cheokchu Golkyeok Julgi Sae Po'
MFGE8 Protein Secretion Linked to Cancer Cells

Terminal cancer patients often suffer severe pain as the cancer frequently metastasizes to the spine before they pass away. The reason for this has not yet been clarified, but recently, a group of scientists published research results that may explain the cause, drawing significant attention.

A research team from Weill Cornell Medicine in New York, USA, published a paper on this topic in the international journal Nature on the 13th (local time). The symptom of cancer cells metastasizing to the spine is commonly observed in breast cancer, lung cancer, prostate cancer, kidney cancer, and others. However, the reason for this has remained unknown. In the 1940s, a theory was proposed suggesting that strong physical impacts such as coughing could momentarily reverse blood flow, causing cancer cells to flow into the spine.

The research team hypothesized that the spine, which exists only in vertebrates, might have been formed through a specialized mechanism because it lacks certain proteins that other bones have. To test this, they extracted stem cells from the spinal bones and thigh bones of mice and analyzed them, confirming that the two types of stem cells express significantly different sets of genes. Furthermore, when spinal stem cells were injected into the muscles of mice, they observed that these stem cells divided into cells resembling spinal cells rather than muscle cells.

Based on this, the research team concluded that these stem cells are a distinct type called 'vertebral skeletal stem cells (vSSCs),' which have different characteristics from those forming other bones. This is a new discovery that challenges the long-held belief among most scientists that all bones in the human body are formed from the same tissue, i.e., the same stem cells. It suggests that stem cells expressed may differ depending on the bone.

In particular, the research team found that this new type of stem cell could explain previously unidentified patterns of cancer metastasis. They focused on the 'MFGE8' protein secreted by vertebral skeletal stem cells. In mouse experiments, removing this protein resulted in a surprising reduction of cancer metastasis to the spine by two-thirds.

The team also extracted and analyzed vertebral skeletal stem cells from patients undergoing spinal surgery. They found that vertebral skeletal stem cells secreting the MFGE8 protein were more likely to interact with cancer cells than those that did not. Professor Noriaki Ono of the University of Texas explained, "We cannot say that one protein causes everything, but (the MFGE8 protein appears to be) a very important factor in causing cancer metastasis to the spine."

The fact that the spine has a unique skeletal formation mechanism different from other bones not only explains the cause of cancer metastasis but may also impact improvements in other orthopedic treatments. For example, spinal fusion surgery, which is attempted to treat conditions such as scoliosis, often fails for unknown reasons. Slavisht Rai, a spinal specialist at a specialized surgical hospital in New York who participated in this study, said, "We hope that further research on vertebral skeletal stem cells will increase the success rate of spinal fusion surgeries."