A protein previously thought to merely hinder the activity of a key cellular protein linked to cancer cell death, now appears to mimic the cellular signaling of that protein; potentially leading to the development of lymphoma. The findings, published in the Aug. 22 online edition of Proceedings of the National Academy of Sciences (PNAS), demonstrate that a viral protein associated with human herpesvirus 8, or HHV8, may help to cause lymphoma by activating a key pathway involved in the production of lymphocytes, a common cell type found in lymphoid tissue that divide over and over and eventually develop into lymphoma.
The protein, called vFLIP K13, had been thought to protect virally infected cells from attack by the body's own immune system by inhibiting the activity of a cellular protein called caspase 8 that is associated with apoptosis, or programmed cell death. However, when Preet M. Chaudhary, M.D. at the Univ. of Pittsburgh School of Medicine, and his colleagues analyzed transgenic mice expressing vFLIP K13, they found that vFLIP K13 failed to block cell death pathways and instead mimicked a recently discovered signaling function of caspase 8, which led to the proliferation of lymphocytes.
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