A small but highly specific stem cell population is responsible for melanoma, the most aggressive skin cancer.
Melanoma is one of the most aggressive cancer that can affect the body: it is the skin cancer that currently affects over 100,000 people in the world , whose incidence has increased by 15 percent over the past ten years
In Europe, melanoma shows the highest incidence rates among the inhabitants of northern countries, with complexion and light eyes. Every year in Italy, we have identified about 10-12 new cases per 100,000 population.
sunlight exposure, especially during the hottest hours of the day and often concentrated in a few weeks a year, is the most important risk factor.
PROGNOSIS The prognosis of cutaneous melanoma, the rate of growth of the tumor is closely tied to the thickness it has reached into the skin at the time of diagnosis and subsequent removal.
In recent years, the survival of this tumor is significantly improved. Through capillary
prevention campaigns and the development of more sensitive diagnostic techniques, it is possible to reach making diagnosis very early, that is when the melanoma has not yet reached the thickness of a millimeter. In these cases the prognosis is very favorable, with survival rates between 87% and 97%. At a time when the thickness of the tumor is greater than three millimeters, the survival rate can drop to 50%.
CANCER STEM CELLS
By definition, the stem cell is a highly undifferentiated cells, with distinct replicative capacity that makes it virtually immortal.
Traditionally, the pathogenic mechanism underlying the tumor development involves the accumulation of a series of random mutations in the DNA of the cell, which ultimately lead the cell itself to an uncontrolled replication.
It is believed that cancer stem cells, also called zero cell, constitutes the very origin of this process, representing the last and most malignant tumor bulwark against drug therapies.
These stem cells, although representing a small part of the pool of tumor cells have a growth rate much lower than the rest of the tumor. This allows them to circumvent the action of the majority of anticancer drugs.
Then, after the apparent eradication of the tumor and the suspension of drug therapy, cancer stem cells are able replicate, generating new cancer cells quickly. In most cases, even these new cells give rise to a tumor more aggressive than the first.
STEM CELLS IN MELANOMA
far, had not been identified stem cells within the melanoma.
A group of researchers at Stanford University School of Medicine in California published in the journal Nature the first identification of cells, classified as stem cells within the melanoma, the most aggressive skin cancer.
The molecule CD271 has in fact been used as the specific marker for the presence of stem cells in melanoma.
stem cells, CD271 positive on their membranes, are rather devoid of other molecules, used as specific targets of anticancer drugs, usually used in the treatment of melanoma.
California Researchers have demonstrated the replicative capacity of cells in tumorigenic CD271 positive sense: in fact, these stem cells are able to generate a melanoma from fragments of human skin transplanted into the experimental model in mice. In contrast, CD271 negative cells are not pout to generate any tissue tumor.
FORWARD
For a long time it was thought that aggression and resistance to drug therapy, proper to the tumors, were due to the very characteristics of malignant cells.
Today, both in melanoma and other cancers, is shedding new light on the very essence of their malignancy and invasiveness.
Within the population of tumor cells, there is a small group of stem cells, immune to many treatments certainly taken to date and able to generate new cancer cells. The discovery of these stem will focus the search for new therapies directly testing the resistance of these cells.
After the recent announcement at the World Congress of Oncology meeting in Chicago (46th Congress of the American Society of Clinical Oncology, ASCO) 's efficacy of a monoclonal antibody (ipilimumab) in activating the immune system against melanoma, overall, even in the face of new knowledge on cancer stem cells, opens new and promising scenarios for the treatment of aggressive skin cancer .
(by Roberto Insolia - Press-Stampa.net)
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