Thursday, March 29, 2018

Pearls collections: What we can learn about infectious disease and cancer

Pearls collections: What we can learn about infectious disease and cancer
Laura J. Knoll, Deborah A. Hogan, John M. Leong, Joseph Heitman , Richard C. Condit

Published: March 29, 2018


Viruses and cancer
Viruses account for an estimated 10% to 15% of human cancers [2]. Currently, the known cancer-causing viruses in humans include seven viruses comprising five virus families [2, 3]. Epstein–Barr virus (EBV)—a herpesvirus—is associated with a variety of malignancies, including for Burkitt lymphoma, diffuse large B cell lymphoma, Hodgkin lymphoma, nasopharyngeal carcinoma, gastric adenocarcinoma, leiomyosarcoma, and posttransplant lymphoproliferative disease. Kaposi sarcoma herpesvirus is the causative agent in Kaposi sarcoma, primary effusion lymphoma, and multicentric Castleman disease. Hepatitis B virus, a hepadnavirus, and hepatitis C virus, a flavivirus, both cause hepatocellular carcinoma. Human T-lymphotropic virus-1, a retrovirus, is responsible for adult T-cell leukemia. Human genital papillomavirus is the causative agent for cervical carcinoma, vulvar cancer, anal cancer, and a number of head and neck cancers. Finally, Merkel cell polyomavirus is responsible for a specific skin cancer called Merkel cell carcinoma. The mechanisms by which viruses cause cancer are under intense investigation and are varied but generally fall into two broad categories: direct and indirect. Direct causation represents the action of viral genes, known in this context as oncogenes, on cellular processes. Indirect causation represents the outcome of chronic inflammation resulting from a persistent viral infection. In no case is cancer the normal outcome of a virus infection. Rather, it is an incidental side effect of the action of viral gene products evolved for the normal process of infection, as in direct causation, or the circumstances of the immune response to infection, as in indirect causation. The identification of viruses as the etiological agent of a number of common cancers provides a unique opportunity to prevent cancer through the use of either vaccination or antiviral drug therapy. Ironically, due to their unique ability to target and kill cells selectively and stimulate a robust immune response, viruses are being developed as “oncolytic” agents to treat cancer.

This compendium of PLOS Pearls includes eight articles that together comprise a survey of the role of viruses in cancer, including mechanism, prevention, and oncolytic agents. Four articles address the mechanism or viral oncogenesis. Moore and Chang explore mechanisms in general and focus on the role of common commensal viruses in cancer [4]. Cavallin et al. discuss the complex mechanisms involved in the induction of Kaposi sarcoma by Kaposi sarcoma herpesvirus [5], and Price and Luftig describe the complexity of EBV latency and its implications for EBV oncogenesis [6]. McBride and Warburton examine the unique role that viral DNA integration into the cellular genome plays in papillomavirus oncogenesis [7]. Three articles address prevention of cancer using antiviral vaccines or drugs. DiMaio provides a succinct history of vaccination, culminating in the development of vaccines for hepatitis B virus and human papillomavirus [8]. Pogoda et al. explore in more depth the development of vaccines for human papillomavirus [9]. Horner and Naggie present an analysis of the successes and challenges surrounding the development of antiviral drugs to treat hepatitis C infections [10]. Lastly, a contribution by Cattaneo and Russell probes the use and potential of viruses to treat cancer, using as an example a remarkable success story on the use of the measles vaccine to treat multiple myeloma [11]. Together, these articles provide insight into the role of viruses in cancer and the hope for cancer therapy that this knowledge brings. The role of viruses in the cause and treatment of cancer is an exciting and expanding area of research, and we can expect significant advances in the future that provide both basic insights into cancer and promise for cancer therapy.
Continue reading this editorial @ PLOS Pathogens 

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