Correlation of gamma-catenin expression with good prognosis in medulloblastomas.

OBJECT: Medulloblastoma is a malignant cerebellar tumor of childhood and is difficult to cure due to frequent cerebrospinal fluid dissemination. Amplification of the c-myc gene (4%) and messenger (mRNA) overexpression (50%) are known to be adverse prognostic indicators. Because mRNA overexpression cannot be explained by gene amplification alone, mechanisms other than gene amplification are postulated. Molecules on the Wnt signal pathway in primary tumors were examined. METHODS: Immunohistochemical and cytogenetic examinations of beta- and gamma-catenin, c-myc, N-myc, and cyclin D1 in 24 primary medulloblastomas were conducted, and their clinical relevance was evaluated. Cytoplasmic/membranous staining of beta- and gamma-catenin was detected in 19 (79%) and nine (37%) cases, respectively, and nuclear expression of cyclin D1 and c-myc was detected in six (25%) and 21 (83%) cases, respectively. The expression levels of gamma-catenin in Western blot analysis and immunohistochemistry were similar. By differential polymerase chain reaction, c-myc and N-myc were amplified separately in two large cell/anaplastic medulloblastomas. No cyclin D1 amplification, or beta- or gamma-catenin mutations were found. Kaplan-Meier analysis revealed no dissemination at diagnosis (Chang Grade M0) and gamma-catenin expression was correlated with good prognosis (p = 0.0002 and 0.003, respectively). Expression of gamma-catenin was also significant in the M0 group (p = 0.022). Expression of cyclin D1 showed a trend toward adverse outcome (p = 0.057) and all patients in whom cyclin D1 expression was found died of disease. CONCLUSIONS: Expression of gamma-catenin is of great prognostic value and its immunohistochemistry may be useful for further stratification of treatment. Cyclin D expression may have the potential to be an adverse prognostic indicator.

Monoclonal CD5+ and CD5- B-lymphocyte expansions are frequent in the peripheral blood of the elderly.

The responsiveness and diversity of peripheral B-cell repertoire decreases with age, possibly because of B-cell clonal expansions, as suggested by the incidence of serum monoclonal immunoglobulins and of monoclonal chronic lymphocytic leukemia (CLL)-like B lymphocytes in clinically silent adults. We phenotyped peripheral blood cells from 500 healthy subjects older than 65 years with no history or suspicion of malignancies and no evidence of lymphocytosis. In 19 cases (3.8%) a kappa/lambda ratio of more than 3:1 or less than 1:3 was found: 9 were CD5+, CD19+, CD23+, CD20low, CD79blow, sIglow (classic CLL-like phenotype); 3 were CD5+, CD19+, CD23+, CD20high, CD79blow, sIglow (atypical CLL-like), and 7 were CD5-, CD19+, CD20high, CD23-, CD79bbright, FMC7+, sIgbright (non-CLL-like). In 2 subjects, 2 phenotypically distinct unrelated clones were concomitantly evident. No cases were CD10+. Polymerase chain reaction (PCR) analysis demonstrated a monoclonal rearrangement of IgH genes in 15 of 19 cases. No bcl-1 or bcl-2 rearrangements were detected. Using a gating strategy based on CD20/CD5/CD79 expression, 13 additional CLL-like B-cell clones were identified (cumulative frequency of classic CLL-like: 5.5%). Thus, phenotypically heterogeneous monoclonal B-lymphocyte expansions are common among healthy elderly individuals and are not limited to classic CLL-like clones but may have the phenotypic features of different chronic lymphoproliferative disorders, involving also CD5- B cells.

Lack of intraclonal diversification in Ig heavy and light chain V region genes expressed by CD5+IgM+ chronic lymphocytic leukemia B cells: a multiple time point analysis.

To analyze the modalities of clonal expansion of chronic lymphocytic leukemia (CLL) cells, we sequenced at multiple time points the V(D)J genes expressed by CD5+IgM+CLL B cells in three patients. All three V(D)J gene sequences were found to be point mutated. The mutation frequency in the Ig VH (3.96 x 10(-2) and 2.41 x 10(-2) change/bp) and Vkappa and Vlambda (6.67 x 10(-2) and 1.74 x 10(-2) change/bp) genes of two CLLs (1.19 and 1.32, respectively) was similar, and higher than that in the corresponding gene segments of the third CLL (1.69; 3.4 x 10(-3) and 6.67 x 10(-3) change/bp). In all three CLLs, there was no preferential representation of nucleotide changes yielding amino acid replacement (R mutations), nor was there any preferential segregation of R mutations within the Ig V gene complementarity-determining regions. In all three CLLs, the somatic mutations were all identical in multiple Ig VHDJH transcripts at any given time point, and were all conserved at multiple time points throughout a 2-yr period. The lack of concentration of R mutations in the complementarity-determining regions and the lack of intraclonal heterogeneity suggest that Ag may no longer be able to play a significant role in the clonal expansion of these cells. This conclusion would be strengthened further by the germline configuration of the bcl-1 and bcl-2 proto-oncogenes that are translocated in neoplastic B cells that display significant traces of intraclonal diversification and Ag-dependent selection, such as B-prolymphocytic leukemia and low grade follicular non-Hodgkin lymphoma.