Biology and treatment of multiple myeloma

Amyloidosis Presenting as Macroglossia and Restricted Tongue Movement

Amyloidosis (AL) is a well recognized cause of macroglossia. A case of localized deposition of systemic amyloidosis secondary to multiple myeloma is reported in a 63-year-old female presenting with restricted tongue movement in the dental setting. Amyloidosis secondary to multiple myeloma is well documented in the literature, with amyloid deposits being found at various sites throughout the oral cavity and systemically. This case emphasizes the importance of a full oral soft tissue examination, including the need to examine mobility of the tissues, as it was the restricted movement of the tongue that ultimately alerted the clinician to the diagnosis. This report also highlights other dental implications of managing patients with multiple myeloma and amyloidosis. Clinical relevance: To provide an understanding of what multiple myeloma and amyloidosis are whilst, importantly, relating this to how these conditions can impact on routine dental treatment.

Relationship of P-selectin glycoprotein ligand-1 to prognosis in patients with multiple myeloma

BACKGROUND

Changes occur in adhesion molecules in the disease course of multiple myeloma. P-selectin glycoprotein ligand-1 (PSGL-1, CD162) works as the ligand of selectin-neutrophil adhesion molecules. The aim of the present study was to investigate the relationship between PSGL-1 expression in the bone marrow and the known prognostic factors for multiple myeloma disease, disease stage, and survival.

MATERIALS AND METHODS

This research included 63 patients with multiple myeloma (26 women [41.3%]; 37 men [58.7%]). The bone marrow biopsy samples obtained at disease diagnosis for each patient were stained immunohistochemically in terms of CD162 expression using standard diagnostic immunohistochemical staining methods. The laboratory results, CD162 expression, overall survival, demographic characteristics of the disease, and the relationship between CD162 expression and the disease stage were evaluated.

RESULTS

Among the 63 patients included in the present study, the survival rate was 82.3% for 1 year, 73.2% for 2 years, 63.4% for 3 years, 51.7% for 4 years, 40.3% for 5 years, and 33.6% for 6 and 7 years. A statistically significant difference was not detected between the CD162 staining ratio and disease survival (P = .232). A statistically significant difference was not detected between the CD162 staining degree and survival rate (P = .184). However, the overall survival of the patients with no CD162 expression in the bone marrow was lower than that for the patients whose CD162 was stained 1, 2, and 3 degrees (12.33 ± 11.49, 28.65 ± 31.44, 37.25 ± 29.32, and 47.92 ± 45.29 months, respectively; P < .001).

CONCLUSION

In the present study, CD162 staining and the staining degree, with the other standard immunohistochemical stains, were shown to be beneficial in the diagnosis of multiple myeloma disease. However, the results did not provide information about the disease course. Studies of a larger number of patients to examine P-selectin and interleukin-6 levels are needed to investigate the disease course.

Loss of p53 exacerbates multiple myeloma phenotype by facilitating the reprogramming of hematopoietic stem/progenitor cells to malignant plasma cells by MafB

Multiple myeloma (MM) is a serious, mostly incurable human cancer of malignant plasma cells. Chromosomal translocations affecting MAFB are present in a significant percentage of multiple myeloma patients. Genetically engineered Sca1-MafB mice, in which MafB expression is limited to hematopoietic stem/progenitor cells (HS/P-Cs), display the phenotypic features of MM. Contrary to many other types of cancer, it is not yet known if the p53 gene plays any essential role in the pathogenesis of this disease. Here, we show, taking advantage of the Sca1-MafB MM mouse model, that loss of p53 does not rescue the multiple myeloma disease, but instead accelerates its development and exacerbates the MM phenotype. Therefore, the efficiency of the MafB-induced MM reprogramming of normal HS/P-Cs to terminally differentiated malignant plasma cells is enhanced by p53 deficiency, in analogy to what happens in reprogramming to pluripotency. These results raise caution about interfering with p53 function when treating multiple myeloma.

A novel molecular mechanism involved in multiple myeloma development revealed by targeting MafB to haematopoietic progenitors

Transgenic expression of the MafB oncogene in haematopoietic stem/progenitor cells induces plasma cell neoplasia reminiscent of human multiple myeloma and suggests DNA methylation as cause of malignant transformation.

Understanding the cellular origin of cancer can help to improve disease prevention and therapeutics. Human plasma cell neoplasias are thought to develop from either differentiated B cells or plasma cells. However, when the expression of Maf oncogenes (associated to human plasma cell neoplasias) is targeted to mouse B cells, the resulting animals fail to reproduce the human disease. Here, to explore early cellular changes that might take place in the development of plasma cell neoplasias, we engineered transgenic mice to express MafB in haematopoietic stem/progenitor cells (HS/PCs). Unexpectedly, we show that plasma cell neoplasias arise in the MafB-transgenic mice. Beyond their clinical resemblance to human disease, these neoplasias highly express genes that are known to be upregulated in human multiple myeloma. Moreover, gene expression profiling revealed that MafB-expressing HS/PCs were more similar to B cells and tumour plasma cells than to any other subset, including wild-type HS/PCs. Consistent with this, genome-scale DNA methylation profiling revealed that MafB imposes an epigenetic program in HS/PCs, and that this program is preserved in mature B cells of MafB-transgenic mice, demonstrating a novel molecular mechanism involved in tumour initiation. Our findings suggest that, mechanistically, the haematopoietic progenitor population can be the target for transformation in MafB-associated plasma cell neoplasias.