Rewarding its previous success, the National Cancer Institute recently renewed a $7.5 million, five-year grant supporting research into viral causes of cancer at the Yale University School of Medicine.

The “Molecular Basis of Viral and Cellular Transformation” grant, currently in its 31st year, supports the research of Daniel DiMaio, the program’s principal investigator, and the work of professors Joan Steitz, George Miller and Joann Sweasy. Understanding viral cancers is critical to trying to fight them, DeMaio said.

“Worldwide about 15 percent of cancers are caused by viruses,” DiMaio said. “Viruses are an important cause of cancer, particularly in the developing world, but they also provide opportunities for treatment and prevention of cancer.”

May Wong, the program director for DNA virus studies at the National Cancer Institute who oversees the grant, said the previously performed research was outstanding and the DiMaio group did “very well in their peer review.”

The different researchers have their own areas of expertise.

DiMaio researches human papillomaviruses and their role in cervical cancer. In large scale studies, more than 95 percent of cervical cancer cases are HPV related.

“It appears to be a necessary cause for cervical cancer, but not sufficient — other things have to go wrong,” DiMaio said.

Most cervical cancer is found outside the United States and is the most common cause of female cancer death in developing countries. While vaccines are being created to combat HPV, DiMaio said they would only be effective in preventing the progression of cancer if administered before infection. Additionally, vaccine researchers need to contend with many strains of HPV to create a vaccine, similar to the process of making a vaccine for many strains of flu virus.

Steitz examines the role of RNA and RNA protein complexes in virus-related cancers, including the Epstein-Barr virus. This virus makes small RNAs in the latent stage of the infection process and is associated with Burkitt’s lymphoma and nasopharyngeal cancer.

“We know that the virus makes small RNAs. The question is what the small RNAs do to the cell,” Steitz said.

Miller also studies the Epstein-Barr virus, along with Kaposi’s sarcoma herpes virus, and focuses on the viruses ability to remain latent and later become activated.

Another aspect of the program focuses on mutant DNA polymerases and their role in causing cancer. Sweasy said she has found that error-prone DNA polymerases can replicate faulty DNA that could cause cancer.

The program’s research has broader applications. Studying virus-related cancers could have an impact on other cancer research. Wong said studying viruses aids scientists’ understanding of cell transformation and what causes a normal cell to become malignant.

“The mechanisms that viruses use to cause tumors are in general related to the mechanisms in non-viral cancers as well,” DiMaio said. “The insights we might gain from studying these particular cancers may also be true in cancers that arise due to other mechanisms.”

By influencing subsequent cancer studies and discoveries, Steitz said the research provides for numerous future applications.