Δευτέρα 26 Σεπτεμβρίου 2011

ECCO 2011-MERKEL POLYOMAVIRUS MECHANISM OF ACTION

Merkel cell polyomavirus causes 80% of Merkel cell carcinoma

20.09.11
Category: Scientific News

The first polyomavirus to be consistently associated with human cancer


Scientists at the University of Pittsburgh Cancer Institute have begun to uncover how the virus that causes most Merkel cell carcinoma – a rare and aggressive skin cancer – operates, meaning that a rational chemotherapeutic target for this cancer could be developed in the near future.

Dr Patrick Moore, an American Cancer Society professor in the laboratory of Yuan Chang and Patrick Moore at the University of Pittsburgh Cancer Institute presented these study results at the Second AACR International Conference on Frontiers in Basic Cancer Research, held in San Francisco, USA (14-18 September, 2011).

Merkel cell carcinoma is a rare and highly aggressive cancer, the incidence of which has increased fourfold during the last 20 years, particularly in immunosuppressed populations.

Merkel cell carcinoma is difficult to treat and clinical trials of chemotherapy agents have been disappointing in term of impact on clinical course of the disease and survival. According to the study authors, discovery of the molecular cause for this cancer provides opportunities to directly target the cellular pathways that are perturbed by the virus.

In 2008, Dr Moore and colleagues discovered Merkel cell polyomavirus (MCV), the virus that causes most Merkel cell carcinoma. Their laboratory previously discovered the herpes virus that causes Kaposi's sarcoma, cancer that commonly occurs in patients with AIDS.

MCV is a natural component of the human skin and is usually harmless meaning that most adults carry the virus in some part of their skin cells. However, if someone becomes immunodeficient and the virus undergoes specific mutations, then it can generate Merkel cell carcinoma. 

In the three years since researchers from Pittsburgh discovered MCV, the group has also discovered several of the unique characteristics of the virus. Most recently, their studies showed that MCV small T antigen protein is a new oncogene that can contribute to abnormal cell growth in both rodent and human cells. In addition, MCV does not act the same as other polyomaviruses that have served as classic models of cancer. These other polyomaviruses depend on viral interaction with the enzyme PP2A and heat-shock proteins; MCV interacts with them, but does not depend on them.

Researcher found that MCV could still cause the abnormal cell growth even after abolishing PP2A and heat-shock protein binding sites. The researchers hope to develop treatments that will directly target the cellular pathways affected by this virus. They have tested more than 1350 drugs to identify better methods to treat this virus-caused cancer.

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