[Significance and contribution to the diagnosis of multiple myeloma according to the IGF1-R gene expression profile].

Multiple myeloma (MM) is a still incurable adult's severe hematologic malignancy. It is characterized by deregulation of several cytokines and their receptors. Among these cytokines, Insulin growth factor 1 (IGF1) and its receptor (IGF1-R) are well documented as major factor of malignant plasma cells growth and survival in multiple myeloma. The objective of this study was to analyze the expression of IGF1-R in multiple myeloma at diagnosis in correlation with clinical and biological data. IGF1-R gene plasma cells expression was studied in 47 patients and 17 controls by Taqman technology RT-PCR. IGF1-R gene was down expressed in the malignant plasma cells of MM patients at diagnosis compared to normal plasma cells, isolated from healthy donors (p = 0.01). Expression decrease was accentuated in the disease advanced stage IIIB. A negative correlation was found between IGF1-R malignant plasma cells expression and the percentage of bone marrow invasion (p = 0.03). Bone marrow infiltration greater than 30% was significantly associated with a low level of IGF1-R gene expression (p = 0.04). Our results suggest that the decreased expression of IGF1-R by malignant plasma cells is a prognostic factor associated with severe disease. Understanding of mechanisms involved in IGF1-R expression negative regulation may contribute to the discovery of new targets therapy in myeloma. the discovery of new targets therapy in myeloma.