The effect of microenvironmental factors on the development of myeloma cells.

Multiple myeloma (MM) is a clonal B-cell malignancy characterized by the accumulation of monoclonal plasma cells (PCs) in the bone marrow and other tissues. Although there are several new therapies, MM remains fatal. The interaction between MM cells and the bone marrow microenvironment promotes drug resistance and cancer cells survival. In our present work, we compared the antigen expression pattern of normal and pathological PCs and investigated the possible connections between various surface receptors, adhesion molecules, and recurrent genetic aberrations. We showed that the expression of CD29, CD27, and CD81 is lower in MM cells than in normal PCs. We found correlation of chromosome 11 hyperdiploidity and the decrease of CD27 expression. We demonstrated that MM cells with CD20 positivity also have CD28 expression. Multiple myeloma patients with active CD29 showed better response to treatment. Our results suggest that these changes may result in an alteration of the interaction between stromal cell and MM cell facilitating cell survival and the development of a more aggressive and resistant phenotype.

Somatic hypermutation of IGVH genes and aberrant somatic hypermutation in follicular lymphoma without BCL-2 gene rearrangement and expression.

BACKGROUND: Follicular lymphoma is characterized by the t(14;18) translocation resulting in constitutive expression of BCL-2 protein; however approximately 10-15% of follicular lymphomas do not express BCL-2 protein, and a small fraction of these cases does not exhibit translocation of the BCL-2 gene either. It is highly debated whether cases of follicular lymphoma without BCL-2 gene rearrangement and expression represent a separate lymphoma entity with distinct biological characteristics, different from the BCL-2-positive cases. DESIGN AND METHODS: To further characterize follicular lymphomas without BCL-2 gene rearrangement and expression, we analyzed and compared the mutational status of IGVH genes as well as other genes (C-MYC, PAX-5 and RHOH) frequently involved in the specific type of genomic instability called aberrant somatic hypermutation in 11 cases of BCL-2-negative and 7 cases of BCL-2-positive follicular lymphomas. We also determined the levels of expression of activation-induced cytidine deaminase in these cases. RESULTS: The analyzed cases were grade 2 and grade 3A follicular lymphomas. Our findings demonstrate that follicular lymphomas without BCL-2 gene rearrangement and expression are associated with ongoing somatic hypermutation of the IGVH genes, low activity of aberrant somatic hypermutation and elevated activation-induced cytidine deaminase expression. These results were in concordance with the results found in the cases of BCL-2-positive follicular lymphoma. CONCLUSIONS: Although, BCL-2 protein overexpression is considered to be a critical pathogenic event in the development of follicular lymphoma, our findings suggest that follicular lymphomas with the same morphology, immunophenotype, mutational pattern and activation-induced cytidine deaminase expression may develop without the involvement of BCL-2 gene. The present data support the hypothesis that BCL-2-positive and BCL-2-negative follicular lymphomas (grades 1-3A) represent a homogenous group with different initial but several common additional molecular pathways.

Quantitative miR analysis in chronic lymphocytic leukaemia/small lymphocytic lymphoma - proliferation centres are characterized by high miR-92a and miR-155 and low miR-150 expression.

Proliferation centres (PCs) are histological hallmarks of lymph nodes in chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL). Chromosomal abnormalities have already been described to accumulate preferably in the PCs as opposed to the intervening small cell areas. To further characterize the pathogenic role of PCs, the expression levels of 17 selected miRs known to be involved in the development of CLL/SLL were compared in the PCs and the intervening small cell areas in lymph nodes of 15 patients with CLL/SLL. The miR expression levels were also compared to the cytogenetic alterations defined by FISH analysis. Our results show that two known oncomiRs, miR-155 and -92a were upregulated and the tumour suppressor miR-150 was downregulated in the PCs. Low expression of miR-150 was also associated with loss of 11q. In summary we found significantly higher expression of oncomiRs and lower expression of a tumour suppressor miR in PCs of CLL/SLL lymph nodes, which support the hypothesis that the PCs may drive the disease and play a role in progression.

Multiple constitutional chromosome translocations of familial nature in Philadelphia chromosome-positive chronic myeloid leukemia: a report on a unique case.

A case of Philadelphia chromosome-positive (Ph(+)) chronic myeloid leukemia (CML) featuring 2 additional balanced translocations, t(2;5) and t(6;12), as well as a robertsonian translocation, t(13;14), was diagnosed by routine bone marrow karyotyping. The breakpoints did not involve previously described CML-related chromosomal regions in any of the 3 translocations. Despite the patient's partial response following imatinib therapy, all Ph(-) bone marrow metaphases persistently had the 3 additional chromosomal changes. Moreover, stimulated peripheral B-lymphocytes from the patient also showed the same chromosomal changes, suggesting that we had found a complex constitutional chromosome aberration unrelated to the leukemia. Peripheral blood karyotype analyses of 6 of the 7 closest relatives from 3 generations demonstrated at least 1 of these aberrations, although in different combinations. Standard bone marrow or peripheral blood karyotyping of hematologic disorders may uncover otherwise symptomless, unrelated constitutional changes together with disease-specific chromosome aberrations.A triple constitutional chromosome aberration combined with a hematologic disorder has not been described until now. In addition, multiple constitutional aberrations persisting through at least 3 generations seem to be extremely rare. At present, no direct evidence exists to support a causative relationship between the familial translocations and leukemogenesis.

High rate of neoplastic cells with genetic abnormalities in proliferation centers of chronic lymphocytic leukemia.

In lymph nodes, chronic lymphocytic leukemia (CLL) cells (prolymphocytes and paraimmunoblasts) form proliferation centers (PCs), which are also known as pseudofollicles. To reveal whether PCs play a role in the accumulation of genetic alterations in CLL, we compared deletion at 11q22.3, 13q14.3, and 17p13.1 loci and trisomy 12 by the fluorescence in situ hybridization (FISH) technique in PCs versus surrounding small lymphocytes (SLs) in 12 formalin-fixed paraffin-embedded (FFPE) lymph nodes. The FFPE sections were stained with methylene blue and PCs were marked by laser beam. Subsequent FISH analysis was performed, relocalizing the previously defined regions. Loss of 11q was detected in five cases, loss of 13q in two cases, loss of 17p in two cases, and trisomy 12 in one case. In seven cases PCs contained a significantly higher ratio of cells with genetic alterations compared with the surrounding SLs. Our results show that CLL cells with genetic alterations tend to accumulate in PCs. The clonal expansion of the cell population carrying genetic alterations within PCs may contribute to CLL progression.

Malignant myoepithelioma of soft tissue: a case report with cytogenetic findings.

Soft tissue malignant myoepithelioma (STMM) is a particularly rare tumor displaying myoepithelial elements and lacking obvious ductal differentiation. From the one case report with cytogenetic data available in the literature, STMM seems to be a distinct entity with some resemblance to chordoma on the one hand and myoepithelioma on the other. The present case of STMM yielded novel data from high-resolution comparative genomic hybridization (HR-CGH) analysis. An 82-year-old female patient presented with a soft tissue tumor within the deep soft tissues in the right gluteal muscle measuring 16 x 13 x 11 cm. Histologically, the lesion was diagnosed as a myoepithelial carcinoma. Immunohistochemistry was focally positive for pancytokeratin, EMA, S-100 protein, and alpha smooth muscle actin. HR-CGH analysis revealed gains of 1p31 approximately p34, 1q21 approximately q23, 9q12 approximately q33, and 16q22 and losses of 1p11 approximately p22, 1q24 approximately q44, 3p, 10q11.1 approximately q22, 13q, 14q13 approximately q24, and 15q. Subsequent fluorescence in situ hybridization analysis confirmed deletion of 3p, gain of 16q, and monosomy of chromosomes 13 and 15. These results support the hypothesis that STMM is a distinct entity, not sharing the cytogenetic alterations of salivary gland myoepithelial carcinomas and ductal carcinomas of breast with myoepithelial differentiation.

IgVH gene mutation status and genomic imbalances in chronic lymphocytic leukaemia with increased prolymphocytes (CLL/PL).

Chronic lymphocytic leukaemia (CLL) with increased prolymphocytes (CLL/PL) has been defined by the World Health Organization (WHO) classification and considered as a progressive and clinically aggressive variant of CLL. To further characterize the biological features of this disease, we performed IgVH gene mutational status, FISH and high-resolution comparative genomic hybridization (HR-CGH) analysis in 17 cases of CLL/PL. All CLL/PL utilized members of VH1, VH3 and VH4 families, with the highest prevalence of the VH1-69 gene. In all but one cases analyzed, the VH genes were unmutated. The FISH and HR-CGH analyses showed frequent occurrence of trisomy 12, del(11)(q23), del(17)(p13) and genetic imbalances, but recurrent genetic lesion characteristic for CLL/PL was not found. The follow-up HR-CGH analysis of two cases showed that increase of prolymphocytes in the course of CLL or CLL/PL are associated with clonal evolution and selection of the tumour clone. In conclusion, this study suggests that CLL/PL is a relatively homogeneous disease regarding VH gene mutation, but heterogeneous regarding genetic lesions. The heterogeneity and high number of genomic imbalances found in CLL/PL suggest that a genome-wide instability of the neoplastic cells may play a role in the development of the disease.

Automated fluorescent in situ hybridization (FISH) analysis of t(9;22)(q34;q11) in interphase nuclei.

BACKGROUND: For chronic myeloid leukemia, the FISH detection of t(9;22)(q34;q11) in interphase nuclei of peripheral leukocytes is an alternative method to bone marrow karyotyping for monitoring treatment. With automation, several drawbacks of manual analysis may be circumvented. In this article, the capabilities of a commercially available automated image acquisition and analysis system were determined by detecting t(9;22)(q34;q11) in interphase nuclei of peripheral leukocytes. METHODS: Three peripheral blood samples of normal adults, 21 samples of CML patients, and one sample of a t(9;22)(q34;q11) positive cell-line were used. RESULTS: Single nuclei with correctly detected signals amounted to 99.6% of nuclei analyzed after exclusion of overlapping nuclei and nuclei with incorrect signal detection. A cut-off value of 0.84 mum was defined to discriminate between translocation positive and negative nuclei based on the shortest distance between signals. Using this value, the false positive rate of the automated analysis for negative samples was 7.0%, whereas that of the manual analysis was 5.8%. Automated and manual results showed strong correlation (R(2) = 0.985), the mean difference of results was only 3.7%. CONCLUSIONS: A reliable and objective automated analysis of large numbers of cells is possible, avoiding interobserver variability and producing statistically more accurate results than manual evaluation.