Aggressive Form of Leukemia Associated with Defective Ribosomes

Twenty to forty percent of the patients with multiple myeloma - a type of leukemia - have a defect in the ribosomes, the protein factories of the cell. Patients with the defect have a poorer prognosis than patients with intact ribosomes. At the same time, these patients respond better to a drug that already exists. These are the findings of a study by the Laboratory for Disease Mechanisms in Cancer at KU Leuven (University of Leuven), Belgium, and collaborators, and published online on December 2, 2016 in the journal Leukemia. The article is titled “RPL5 on 1p22.1 Is Recurrently Deleted in Multiple Myeloma and Its Expression Is Linked to Bortezomib Response. Multiple myeloma (MM, also known as Kahler's disease) is a blood cancer in which the plasma cells in the bone marrow start proliferating malignantly. MM cannot be cured and is most common among older people. Various treatments exist to temporarily suppress the disease, but the challenge is determining to which treatment the patient will respond best. Doctoral student Isabel Hofman (KU Leuven) discovered defects in the ribosomes of MM patients. “In MM patients, one part of the ribosome is produced less in 20 to 40 percent of the patients, depending on how aggressive the cancer is. We suspect that their cells are still producing protein, but that the balance is somewhat disrupted. In any case, we found that these people have a poorer prognosis than MM patients with an intact ribosome," explained Professor Kim De Keersmaecker (photo), head of the KU Leuven Laboratory for Disease Mechanisms in Cancer. One possible treatment for MM is the use of proteasome inhibitors. "The proteasome is the protein demolition machine in a cell,” Dr. Keersmaecker said. “There's a type of drug, including bortezomib, that inhibits its functioning.
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