Wednesday, June 17,
2009
In a series of recently-published articles, a research team from
the University of North Carolina at Chapel Hill Lineberger
Comprehensive Cancer Center has uncovered clues to the development
of cancers in AIDS patients.
In an April article published in the journal PLoS Pathogens, Dirk
Dittmer, Ph.D. associate professor of microbiology and immunology
at UNC's School of Medicine, demonstrated 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. This represents a collaborative effort between UNC
researchers and clinicians at Beth Israel Hospital, the University
of Miami and the Federal University in Bahia, Brazil.
MicroRNAs are small molecules that regulate gene expression.
Scientists have 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.
Dittmer's team examined samples of tissue provided with the consent
of Kaposi's sarcoma patients and found that specific miRNA
biomarkers accurately identify stages of tumor progression. They
found that certain miRNAs were lost as the tumors progressed,
effectively accelerating the cancer's growth. More aggressive tumor
stages expressed higher levels of KSHV miRNA.
In second study, published June 4 in the journal Blood, the team
looked for the presence of tumor 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.
His team found that several miRNAs known to suppress tumor 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.:"
Scientists 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.
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University of North Carolina School of Medicine
Thanks to University of North
Carolina School of Medicine for this article.