Global gene expression profiling in the study of multiple myeloma.

Multiple myeloma (MM) is a rare but uniformly fatal malignancy of antibody-secreting plasma cells. Although several key molecular events in disease initiation or progression have been confirmed (eg, FGFR3/MMSET activation) or implicated (eg, chromosome 13 deletion), the mechanisms of MM development remain enigmatic. Although it is generally indistinguishable morphologically, MM importantly exhibits a tremendous degree of variability in its clinical course, with some patients surviving only months and others for many years. However, measures of current laboratory parameters can account for no more than 20% of this outcome variability. Furthermore, the means by which current drugs impart their anti-MM effect are mostly unknown. The development of serious comorbidities, such as osteopenia and/or focal lytic lesions of bone, is also poorly understood. Finally, very little knowledge exists concerning the molecular triggers for the conversion of benign monoclonal gammopathy of undetermined significance (MGUS) to overt MM. Given that abnormal gene expression lies at the heart of most if not all cancers, high-throughput global gene expression profiling has become a powerful tool for investigating the molecular biology and clinical behaviors Here I discuss recent progress made in addressing many of these issues through the molecular dissection of the transcriptome of normal plasma cells, MGUS, and MM.