Morphological Criteria, expression of Cyclin D1 and p53 and beta-2 microglobulin level at different stages of Multiple Myeloma

Introduction.
The bone marrow biopsies in patients with multiple myeloma (MM) are usually analyzed by some morphological criteria which can help to make survival rate prognosis, which can be: plasma cell morphology (size, blastic or pleomorphic features etc.), the volume of infiltration and the pattern of neoplastic growth (Sailer M et al., 1995; Bartl R., et al. 2002; Subramanian R, et al., 2009). Malignant plasma cells express such aberrant markers as p53, cyclin D1 and the role of them in the prognosis and survival in literature is reflected contradictory (Ngo,et al., 2009; Teoh, Chng, 2014; Athanasiou, et al., 2001).
The aim of the study was to analyze morphological and immunohistochemical features of bone marrow in correlation with different stages by Salmon- Durie (SD) and β-2 microglobulin level (β-2MG)
Material and methods.
We have analyzed 122 patients with primary diagnosed MM from 2011 to 2015 in Riga Eastern Clinical University Hospital’s Hematology centre at different SD stages and
β-2MG level. All bone marrow biopsies were stained with hematoxylin-eosin, Gordon-Sweet's reticulin silver and Cyclin D1 and p53 were detected. Statistical analysis was performed with Graph Pad Prism 5 version software.
Results.
Analyzed patients were at such SD clinical stages: I (20%, n =24); II (45%, n = 55); III (35%, n = 43). Mean age of patients was (Mean ±SD) 64.88 ± 10.01 years, β-2MG mean level was 4.9 ± 4.47 mg / dL.
We proved that increased β-2MG level statistically significantly correlated with increased BM cellularity (p < 0.0001; r = +0.45), increased plasma cells in BM (p < 0.0001; r = +0.47), high level of plasmocytes with plasmoblastic differentiation (p = 0.0001; r = +0.34), the bone marrow infiltration type with plasma cells (p < 0.0001; r = +0.43), overexpression of p53 (p = 0.0025; r = +0.27) and Cyclin D1 (p = 0,033; r = +0,19).
Cyclin D1 positive patients group had statistically significant (p = 0.034) higher β-2MG level (5.5 ± 4.58 mg / dL) than those of the Cyclin D1 negative group (4.27 ± 4.3 mg / dL).
Patients with p53 + myeloma cells had statistically significant (p = 0.029) higher β-2MG level 5.84 ± 4.66 mg / dL than those of the p53 negative group 4.37 ± 4.37 mg / dL.
Statistically significant associations were found between MM advanced SD clinical stage and increased bone marrow cellularity (p < 0.0001; r = +0.4) as well as with increased amount of myeloma cell (p < 0.0001; r = +0.5), high number plasmoblastic differentiation of MM cells and BM infiltration type of myeloma cells (p < 0.0001; r = +0.44).
Positive correlation was found between Cyclin D1 expression and SD clinical staging system (p = 0,002; r = +0, 28), as well as were obtained with p53 (p < 0.0001; r = +0.41) expression and SD stages.
Cyclin D1 and p53+ patients group showed late stages of MM by SD classification than those with the lack of Cyclin D1 (p = 0.0025) and p53 (p < 0.0001)
Cyclin D1+ patients group accordingly S-D staging was: I (10%, n = 6); II (45%, n = 28) ; III (45%, n = 28), but Cyclin D1 negative patients stages: I (30%, n = 18); II (45%, n = 27); III (25%, n = 15).
But S-D stages in patients with p53 expression was: I (5%, n = 2): II (36%, n = 16) : III (59%, n = 26), but patients with lack of p53 antigen SD staging ratio was: I (28%, n = 22) : II (50%, n = 39) : III (22%, n = 17).

Conclusions.
1. Our study showed that high BM cellularity and plasma cells level, as well as high number of plasmocytes with plasmoblastic differentiation and BM diffuse infiltration of plasma cells significantly correlated with advanced SD stages and high β-2MG level and demonstrated poorer prognosis for MM patients.

2. Increased p53 and cyclin D1 expression possibly influence the progression of MM, expression of Cyclin D1 correlated with late stages of MM and this marker is indicator for poorer prognosis for patients.