In a series of articles researchers at the University of North Carolina at Chapel Hill Lineberger Comprehensive Cancer Center have uncovered clues to the development of cancers in AIDS patients.
Dr. Dirk Dittmer of UNC's School of Medicine writes in a study paper published in the journal PLoS Pathogens in April that the Kaposi sarcoma associated herpesvirus (KSHV) is not only present in every tumor cell, but that the cells also transcribe microRNAs (miRNA) from the virus.
MicroRNAs are small molecules that regulate gene expression.
The research team-which also included clinicians from Beth Israel Hospital, the University of Miami and the Federal University in Bahia, Brazil-hypothesized that viruses can cause cancer through a mechanism where the viral genes take over the cell and induce cancerous growth through alteration of cell miRNA, since certain kinds of miRNA are responsible for putting the 'brakes' on uncontrolled cell growth.
Examining samples of tissue provided with the consent of Kaposi's sarcoma patients, the researchers found that specific miRNA biomarkers accurately identify stages of tumour progression.
They found that certain miRNAs were lost as the tumours progressed, effectively accelerating the cancer's growth. More aggressive tumour stages expressed higher levels of KSHV miRNA.
Another study published in the journal Blood on June 4 looked for the presence of tumour suppressor mRNAs in primary effusion lymphoma and Kaposi's Sarcoma.
"We chose these two cancers because, while they are both associated with the same virus, they occur in very different types of cells," Dittmer noted.
He and his colleagues observed that several miRNAs known to suppress tumour activity were significantly less active in both types of cancer.
"Micro RNAs are an exciting new class of cancer markers. Knowing which ones are present in a particular tumor will help us understand the biology and develop those micro RNAs as novel cancer therapy targets," he said.
The researchers believe that finding the mechanisms through which viruses take over cellular systems, resulting in cancer, is a promising strategy for cancer prevention and treatment, since it is much more feasible to block viral infection or develop specific inhibitors of the viral genes than try to inhibit all of the genetic changes within a cancer.