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UV light and papilloma viruses are a dangerous combination, which leads increasingly to skin cancer
When it comes to skin cancer, many people think of UV rays first. These have long been considered a known risk factor for the development of skin cancer. Researchers have now found that infection with human papilloma viruses associated with UV light promotes the development of white skin cancer.
In their current investigation, the scientists of the German Cancer Research Center (DKFZ) found that a combination of UV rays together with a simultaneous infection with human papillomavirus favors the development of white skin cancer. The experts published a press release on the results of their study.
Researchers investigated why the viruses can only be detected in benign cancer precursors
It has long been believed that UV rays, along with human papillomavirus infection, could promote skin cancer. This is particularly true for organ transplant recipients, the researchers say. The scientists at the German Cancer Research Center have now been able to demonstrate for the first time in a natural system that papilloma viruses in connection with UV light can promote the development of white skin cancer. The results of the investigation provide an explanation as to why the viruses in human beings can be no longer detectable in benign pre-cancerous stages but in advanced cancer.
Every person gets infected with human papilloma viruses at some point
In the course of life, every person becomes infected with so-called skin-typical (cutaneous) human papilloma viruses (HPV). The infection usually occurs early in childhood. In healthy people, the immune system is able to fight off the viruses. The defense against the human papillomavirus decreases with age.
Donors of donor organs are particularly at risk
Donors of donor organs whose immune system is suppressed with medication in the long term are particularly at risk. Affected people have an up to 250-fold higher risk of developing white skin cancer, the authors say. The incidence of this cancer has also increased in recent years. UV radiation is an important known risk factor for the development of white skin cancer. This type of cancer occurs preferentially on parts of the body exposed to the sun, the doctors explain further. So far, however, there has been insufficient evidence of the influence of certain types of human papillomavirus (HPV) on the development of cancer.
Trials on mice gave evidence
Scientists at the German Cancer Research Center (DKFZ) under the leadership of Frank Rösl have now succeeded in providing evidence of this connection. In their study, the researchers examined mice, which usually develop an infection from papilloma viruses shortly after birth. Rösl and his team compared animals infected by the virus with non-infected peers. The mice were then treated with a dose of UV radiation which is comparable to exposure to the sun during a vacation in Mediterranean latitudes. Finally, only the infected animals developed white skin cancer (squamous cell carcinoma).
Viruses affect the stability of the genetic makeup of their host cell
One group of the tumors was horny, but the other group was not. The so-called horny tumors contained large amounts of viruses, such as those found in pre-cancerous diseases (so-called actinic keratosis) in humans, the experts say. The upper layers of the skin grow excessively, but still remind of the original structure of the skin. The results of the study showed that the viruses impair the stability of the genetic makeup of their host cell. This leads to a promotion of the accumulation of UV damage.
The tumor-promoting influence of cutaneous papilloma viruses was demonstrated for the first time
The second group of tumors examined did not contain viruses, as is the case with advanced carcinomas. In the course of the investigations, antibodies in the blood of the animals could also be found in such cases, which indicated a previous virus infection. Such tumors often show mutations in a gene that is particularly important for the cell (p53), the researchers explain. In humans, this gene is defective in the majority of squamous cell carcinomas. This leads to unhindered growth. "This is the first direct evidence of the tumor-promoting influence of cutaneous papilloma viruses in a natural system that is very similar to the situation of patients," says the expert Frank Rösl.
The amount of virus is related to the differentiation of the tumor
An uncontrolled growth of cells causes tumors to degenerate even further, the doctors explain. This prevents the viruses that have now become superfluous for tumor growth from multiplying further. The lack of viruses in advanced carcinomas has been a major argument against the involvement of cutaneous papilloma viruses in the development of cancer. “We are showing for the first time that the amount of virus is related to the differentiation of the tumor. This relationship has never been examined in detail in previous studies of patient biopsies, ”explains the lead author of the study, Daniel Hasche.
More research is needed
According to the doctors, the missing examinations should now be made up for. According to the scientists from the German Cancer Research Center, the findings are an important argument for the development of vaccines against cutaneous papillomaviruses. Such a drug would be particularly important for organ transplant recipients, because it is precisely these people who often develop white skin cancer, the authors add. (as)