Researchers Find New Link Between Human Papillomavirus and Cancer
Findings in today's issue of EMBO Journal
September 15, 1999
A University of Rochester Medical Center researcher has found how human papillomavirus, a sexually transmitted virus that causes nearly all cases of cervical cancer, arrests the life cycle of cervical cells to allow itself to flourish. The findings, reported in today's issue of the Journal of the European Molecular Biology Organization, also suggest how the virus keeps its presence hidden from the body's immune system.
Cervical cancer is the most common cancer-related cause of death worldwide. Primarily a sexually transmitted disease, human papillomavirus (HPV) is most rampant in third world countries where there are no regular Pap smear tests. Pap smears show early signs of HPV infection, but are not always accurate. Understanding exactly how HPV manipulates a cell could lead to better detection or treatment of the infection.
In order to thrive, HPV must stop a cell from going through a natural process called differentiation. For differentiation to occur, two proteins, called co-activators, must connect like a plug and electrical outlet. HPV, however, has a protein called E6 that acts like a childproof outlet cover, sticking to the outlet and preventing the plug from inserting.
"The broad implications of these findings are that they may help to explain how E6 acts in concert with other viral proteins to inhibit cell differentiation with the subsequent development of cancer," explains Dennis McCance, Ph.D., professor of Microbiology and Immunology at the University of Rochester. "In fact, cervical cancer is probably the best understood example of how viral infections can lead to cancer."
HPV delivers a one-two punch as it attacks a cell. After it inhibits differentiation, it inhibits an effective immune response because the same plug-and-outlet proteins that E6 has blocked would normally alert the immune system.
Until McCance's findings, scientists knew that the co-activators were integral to cell differentiation and that E6 disrupted cell differentiation, but this is the first time there has been a clear connection drawn between the two.