U. Md. researchers show how bacterial infections can contribute to cancer


WASHINGTON — About 20 percent of cancers involve bacterial or viral infections — and medical researchers at the University of Maryland are zeroing in on an explanation.

Researchers at the University of Maryland School of Medicine’s virology institute say a protein found in a family of bacteria could be a trigger in a series of events that lead to cancer.

The villain in this story is a specific DNA sequence involving the chaperone protein DnaK, found in a genus of bacteria called mycoplasma — a group of microorganisms linked to cancers, especially in people with HIV.

“The majority of bacteria don’t carry this precise (DnaK) sequence … but, what we have found is that the bacteria that do carry this sequence are those, in fact, that have been reported by others to be associated with an increased cancer risk,” said Dr. Robert Gallo, director of the school’s Institute of Human Virology. “So, we’re putting two and two together.”

Gallo said the new research shows that bacteria with the DnaK gene sequence are friendly to cancer in three ways. They inhibit the ability of cells to repair themselves, suppress a “guardian” protein that would normally cause defective cells to self-destruct, and also inhibit the effectiveness of certain cancer-fighting drugs.

Gallo imagines a future where, after more research, clinical trials and ongoing work with oncologists, there might be a new way to help prevent cancer in at-risk groups.

“If these particular bacteria are around, and if we have safe therapy against those particular bacteria, I would foster considering antibiotic therapy,” he said.

“We have a lot more to do,” Gallo said, while noting there has yet to be human clinical trials on this. The newly reported findings involve research with immune-compromised mice and their propensity for developing lymphoma when infected with bacteria carrying this particular sequence of DnaK.

So, what’s next?

“We want to study a number of other bacteria that harbor this sequence and show that they have the same damaging effect in cells,” Gallo said.

He added, “We want to see if we can show demonstrably that those bacteria’s gene products also harm the ability for DNA to repair itself and for the ‘guardian of the genome’ to be itself impaired. We want to extend (the research) out to other bacteria.”