Cancer, infection and epigenetic link emerges

Kathleen Blanchard's picture
Cancer and infection
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Researcher Richard A Stein, PhD, MD suggests an emerging link between infection, epigenetics and cancer. Changes brought about by inflammation from pathogens can turn cells into cancerous tumors. Many cancers are linked to viruses that promote reversible, epigenetic changes in the body’s cells that lead to tumors.

Twenty percent of cancers linked to infection

Today, “20% of cancers have been causally linked to human pathogens”, writes Dr. Stein in a commentary published in the Journal of the American Medical Association (JAMA). Why some cells turn into cancer is “still a mystery”, but epigenetic changes appear to play an important role in why cancer develops.

Changes in the way genes are expressed – or epigenetic changes in DNA – “varies from one cell to another”, says Stein, and within the same cell, those changes can mean the difference “between health and disease states.”

Dr. Stein suggests more focus is needed to understand the causal link already seen between some types of cancer and infectious diseases that could be controlled. Understanding why some infections turn cells into cancer would lead to new prevention and treatment strategies.

Infections that cause cancer

Stein explains viruses have been linked to cancer since 1911, when Peyton Rous showed cancer could be induced in healthy chickens by injecting a virus. Rouse won the Nobel Prize in Physiology or Medicine in 1966. His discovery that cancer was linked to virus was met with disbelief. Further research showed viruses and environmental factors may induce cancer or make it worse.

Stein writes, “A century after this major finding, more than 20% of cancers have been causally linked to human pathogens.”

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The Hepatitis B virus that raises the risk of liver cancer 100 fold, the human papillomavirus (HPV) that is linked to 70 percent of cervical cancers, respiratory papillomatosis and a portion of head and neck cancers are examples of cancer brought about by viruses that cause epigenetic changes, methylation of DNA and RNA disruption that lead to abnormal cell growth and cancerous tumors.

Stein also notes, “Epstein-Barr virus, the first virus to be associated with human cancer, infects more than 90% of the population worldwide and has been linked to nasopharyngeal carcinoma, Burkitt lymphoma, Hodgkin disease, and lymphoproliferative tumors in immunocompromised individuals.”

All three diseases are global health concerns, caused by viruses, and linked to cancer.

The interaction between viruses and DNA methylation and other changes in cells that lead to cancer are complex. Inflammation from infection that can lead to cancer are demonstrably “important steps during tumor genesis or progression”, explains Dr. Stein.

“Epigenetic changes increasingly emerge” as causing cancer, he adds, and those changes can be linked to viral infection. One pathogen or virus can modify genes in a variety of complex ways that can lead to cancer and should be further explored.

JAMA: 2011;305(14):1484-1485. doi: 10.1001/jama.2011.446
"Epigenetics—The Link Between Infectious Diseases and Cancer"
Richard A. Stein, MD, PhD
Department of Molecular Biology, Princeton University, Princeton, New Jersey

Image credit: Wikimedia commons
Source: Laboratory of Tumor Virus Biology

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