RESUMO
Multiple myeloma (MM) is a clonal disorder of terminally differentiated B cells. In some cases the premalignant state is monoclonal gammopathy of undetermined significance (MGUS). Neoplastic plasma cells in both entities carry multiple and complex chromosomal abnormalities that make understanding of the disease development difficult. New insight into malignant mechanisms that underlie multiple myeloma may come from forkhead box P1 transcription factor (FOXP1) analysis in neoplastic plasma cells. FOXP1 is known to be important for B-cell maturation and differentiation and could play a significant role in plasma cell tumors. The purpose of the present study was therefore to analyze FOXP1 protein presence and FOXP1 gene abnormalities in 13 cases of MGUS and 60 cases of MM. It was found that FOXP1 protein was expressed in neoplastic plasma cells, unlike in their normal counterparts, and that additional FOXP1 gene copies could be found in both MGUS and MM. Based on FOXP1 presence in MM and its role in diffuse large B-cell lymphoma and extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, FOXP1 might play an important role in plasma cell neoplasm.
Assuntos
Fatores de Transcrição Forkhead/metabolismo , Gamopatia Monoclonal de Significância Indeterminada/metabolismo , Mieloma Múltiplo/metabolismo , Proteínas Repressoras/metabolismo , Idoso , Biomarcadores Tumorais/análise , Feminino , Fatores de Transcrição Forkhead/genética , Expressão Gênica , Humanos , Imuno-Histoquímica , Hibridização in Situ Fluorescente , Masculino , Gamopatia Monoclonal de Significância Indeterminada/genética , Gamopatia Monoclonal de Significância Indeterminada/patologia , Mieloma Múltiplo/genética , Mieloma Múltiplo/patologia , Proteínas Repressoras/genéticaRESUMO
Notch signaling is implicated in the pathogenesis of multiple myeloma expressing high level of active Notch proteins NOTCH1 and JAGGED1 in tumor plasma cells. We investigated expression of NOTCH1 and JAGGED1 in bone marrow trephine biopsies of 80 newly diagnosed multiple myeloma and 20 monoclonal gammopathy of undetermined significance patients using immunohistochemical methods. The number of positive tumor cells was counted per 1000 tumor cells and the intensity of staining was assessed semi quantitatively. Multiple myelomas expressed NOTCH1 in 92.31% (72/78) and JAGGED1 in 92.21% (71/77) cases. NOTCH1 staining was strong in the majority of cases (59.7%), whereas JAGGED1 was predominately weak (67.6% of cases). In contrast, both markers were negative in all monoclonal gammopathy of undetermined significance cases. However, upon progression of disease from monoclonal gammopathy of undetermined significance to multiple myeloma (seen in 4 patients), analysis of the subsequent bone marrow biopsy showed weak expression of both markers in tumorous plasma cells. Immunohistochemistry results were compared with the pattern of bone marrow infiltration, plasma cell differentiation, and the presence of t(11;14)(q13,q32), t(14;16)(q32;q23),and t(4;14)(p16.3;q23) and overall survival in multiple myeloma patients. A significant correlation was found between strong NOTCH1 staining in multiple myeloma plasma cells and the diffuse type of bone marrow infiltration (P = .002) and an immature morphologic type of plasma cells (P = .043). After a median follow-up of 20.3 months, in multiple myeloma patients no difference in overall survival between NOTCH1 (P = .484) and JAGGED1 (P = .822) positive and negative cases were found. In conclusion, our results indicate importance of NOTCH1 and JAGGED1 expression in plasma cell neoplasia and a possible diagnostic value of their immunohistochemical evaluation of bone marrow infiltrates for multiple myeloma.