Better Understanding of Tumor Growth
A new paper published by a research team from the PUPSMD (Plymouth Unverisity Peninsula Schools of Medicine and Dentistry), in the United Kingdom, reveals that if a specific tumor suppressing protein is lost, the result leads to an abnormal proliferation of nervous cells, thus leading to the development of tumors in both the central and peripheral nervous systems. The paper was published at the end of last week, in the journal Brain.
According to the research team there are numerous tumor suppressing proteins in the human cells. The loss of a specific tumor suppressing protein, called “Merlin” (also known as Neurofibromin-2 or schwannomin), causes the development of tumors in several types of cells that make up the nervous system. Each cell contains two copies of this tumor suppressing protein. One of the copies is inherited from the paternal chromosome, while the other is inherited from the maternal chromosome. Researchers say that there are two possible scenarios for the loss of “Merlin”. The first way the copies can be lost is by an accidental loss of both copies from a single cell. This loss could be the cause for sporadic nervous tumors. The second process involves the inheritance of one abnormal copy of the tumor suppressing protein, and the loss of the healthy copy throughout one’s life. This loss causes the onset of NF2 (Neurofibromatosis type 2).
Both pathways leading to the loss of the “Merlin” protein cause the development of tumors from myelinating Schwann cells. These are the cells that create the myelin sheath around the axons of both motor and sensory neurons. The tumors derived from Schwann cells are called schwannomas. However, the loss of the tumor suppressor can also lead to tumors forming from other cells from the nervous system, such as the cells responsible for the lining of the brain’s ventricular system and the spinal cord, known as ependymal cells.
Even though schwannomas are mostly benign (only 1% of schwannomas turn malignant) and have a slow growth rate, they occur frequently. Usually, a patient has more than one tumor, which eventually leads to hearing impairment, disability and even death. There have been reported cases of patients with more than 20 separate tumors at the same time. There is no known treatment for schwannomas, except for repeated surgical interventions and single-tumor targeted radiotherapy. Both treatment schemes are very unlikely to fully remove the cancerous tissue.
In their current study, researchers investigated the mechanism through which the loss of Sox10, another protein, causes the development of tumors. The Sox10 protein has been reported to play a major part in the growth of Schwann Cells, however, this is the first study that reveals its implication in the growth of schwannomas. Due to their understanding of the process, the researchers open a new path for future cancer therapies that might provide a more effective alternative to the already existing treatment plans.
Professor David Parkinson is the leader of the research team, comprised of scientists from PUPSMD, SUNY (State University of New York) and FAU (Friedrich-Alexander-UniversitÃ¤t Erlangen-NÃ¼rnberg). “We have for the first time shown that human schwannoma cells have reduced expression of Sox10 protein and messenger RNA. By identifying this correlation and gaining an understanding of the mechanism of this process, we hope that drug-based therapies may in time be created and introduced that will reduce or negate the need for multiple surgery or radiotherapy”, reported Parkinson as a conclusion.