Analysis of bcl-6 protein expression and gene rearrangement in diffuse large B-cell lymphoma / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate bcl-6 protein expression and gene rearrangement patterns in diffuse large B-cell lymphoma (DLBCL) and their clinicopathologic significance.</p><p><b>METHODS</b>Immunohistochemical studies for bcl-6 and CD10 proteins were performed on 51 cases of DLBCL paraffin-embedded tissues (including 22 nodal samples and 29 extranodal samples) and 10 cases of reactive lymphoid hyperplasia (RLH) paraffin-embedded tissues. Interphase fluorescence in-situ hybridization (FISH) with dual color breakapart probe was also used to identify rearrangement of bcl-6 gene in 32 cases of nodal DLBCL tissues (including 22 paraffin-embedded samples and 10 fresh samples) and 5 cases of RLH paraffin-embedded tissues.</p><p><b>RESULTS</b>(1) The rates of bcl-6 protein expression in nodal DLBCL, extranodal DLBCL and RLH were 72.7% (16/22), 75.9% (22/29) and 100.0% (10/10) respectively. The rates of CD10 expression were 40.9% (9/22), 41.4% (12/29) and 100.0% (10/10) respectively. All lymphoma samples which expressed CD10 also showed co-expression of bcl-6 protein. (2) The co-expression of bcl-6 and CD10 was observed in 40.9% (9/22) nodal DLBCL and 41.4% (12/29) extranodal DLBCL. Low clinical stage (stage I and II) was more frequently observed in cases with co-expression of bcl-6 and CD10 (P < 0.05). (3) The rates of bcl-6 gene rearrangement in nodal DLBCL was 28.1% (9/32), with 27.3% (6/22) in paraffin-embedded tissues and 30.0% (3/10) in fresh tissues. There was no statistically significant difference found between the two groups (P > 0.05). Bcl-6 gene rearrangement was not found in all the 5 cases of RLH, and there was a significant difference between RLH and DLBCL (P < 0.05).</p><p><b>CONCLUSIONS</b>The rate of bcl-6 protein expression is high in DLBCL cases, and the detection of bcl-6 and CD10 protein co-expression may help in the diagnosis and differential diagnosis of DLBCL. Those DLBCL cases with co-expression of bcl-6 and CD10 may also have a better prognostic implication. On the other hand, bcl-6 gene rearrangement can be identified by interphase FISH with dual color breakapart probe in both paraffin-embedded and fresh lymphoma tissues.</p>

Study of mutations in 5'-noncoding region of BCL-6 gene in B-cell non-Hodgkin's lymphomas / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate BCL-6 gene mutations in B-cell non-Hodgkin lymphomas (B-NHL) and their implications in lymphoma pathogenesis.</p><p><b>METHODS</b>Polymerase chain reaction (PCR) and direct DNA sequencing methods were used to identify mutations in the 5'-noncoding region of BCL-6 gene in 135 cases of B-NHL, 5 cases of T-NHL, 5 cases of nodular lymphocyte predominance Hodgkin's lymphoma (NLPHL) and 10 cases of reactive hyperplasia of lymph node.</p><p><b>RESULTS</b>Mutations were identified in 6 cases of nodal DLBCL (27.3%), 4 cases of FL (22.2%), 4 cases of MALT lymphoma (22.2%), 4 cases of extranodal DLBCL (20.7%) and 2 cases of LRH (20%). No mutations were detected in T-NHL and NLPHL (P < 0.05). There were no significant differences in incidences of BCL-6 gene mutations between nodal and extranodal DLBCL (P > 0.05). All mutations were base substitutions and the frequency of single-base change was 0.14 x 10(-2)/bp approximately 0.68 x 10(-2)/bp.</p><p><b>CONCLUSIONS</b>Mutations of the 5'non-coding region of BCL-6 gene may be involved in the pathogenesis and progression of B-NHL. Molecular demonstration of such mutations may provide a marker of lymphomas derived from the germinal center-related B cells.</p>

Mismatch pair defective phenotype in hereditary nonpolyposis colorectal cancer in the Chinese / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To study the protein expression pattern of DNA mismatch repair genes hMSH(2), hMLH(1) and the microsatellite instability (MSI) status in the tumor tissue from hereditary nonpolyposis colorectal cancer in the Chinese.</p><p><b>METHODS</b>Fifty-eight families fulfilling different clinical criteria including Amsterdam Criteria (AC) (22/24 families, 38 tumors), Japanese Criteria (JC) (12/15 families, 16 tumors) and Bethesda Guidelines (BG) (12/19 patients, 13 tumors) were studied. Monoclonal antibodies against hMSH(2), hMLH(1) proteins and a panel of microsatellite markers (5 loci) including BAT26, BAT25, D2S123, D5S346 and D17S250 were used for study.</p><p><b>RESULTS</b>MSI-H was identified in all 22 (100%) AC tumors, with 81.8% (18/22) showing altered hMSH(2) or hMLH(1) expression; in 14/15 (93.8%) JC cancer, 1/1 (100%) JC adenoma, with 45.5% (5/11) showing altered hMSH(2) or hMLH(1) expression; and in 7/13 (53.8%) BG tumors, with 4/7 showing loss of hMSH(2) or hMLH(1) gene expression.</p><p><b>CONCLUSION</b>The frequency of MSI-H and loss of mismatch repair protein are different in the families fulfilling different clinical criteria. Amsterdam Criteria and Japanese Criteria are the two most useful criterion systems for identifying mismatched repair defective tumors. However, Bethesda Guidelines should also be used for detecting more such tumors. The combination of immunohistochemical methods and microsatellite instability analysis is an effective strategy to detect the mismatch repair defective tumors. A close correlation does exist between hMSH(2), hMLH(1) protein expression pattern and MSI status.</p>

Mutation analysis of hMSH2 and hMLH1 genes in Chinese hereditary nonpolyposis colorectal cancer families / 中华病理学杂志

<p><b>OBJECTIVES</b>To determine the germ-line mutations of hMSH2 and hMLH1 genes in Chinese hereditary nonpolyposis colorectal cancer (HNPCC) families' probands or in patients fulfilling different clinical criteria or guidelines; to clarify the nature and distribution of the mutations; to evaluate the sensitivity of different clinical criteria in mutation prediction.</p><p><b>METHODS</b>The entire coding regions (35 exons including exon-intron boundaries) of hMSH2 and hMLH1 genes were directly sequenced in 24 Amsterdam criteria (AC) probands, 15 Japanese criteria (JC) probands (except AC kindreds) and 19 Bethesda guidelines (BG) patients (except two former groups). All available affected and unaffected members from families of those with mutations were screened for mutation.</p><p><b>RESULTS</b>In 16 unrelated families selected by the different clinical criteria, 17 germ-line mutations were found with 11 (64.7%) of hMLH1 and 6 (35.3%) of hMSH2. Two mutations were identified in one of the families. Among the 17 germ-line mutations, 12 had not been reported previously. A diversified mutation spectrum was found, but 6 hMLH1 mutations were found to be concentrated in the region encompassing exon 14, 15 and 16. There was a wide spectrum of mutation type including frame shift, nonsense, splice site mutation, in frame insertion or deletion and missense mutations. The mutation detection rate of hMSH2 and hMLH1 in the AC group was significantly higher than that in the JC group (12/24 vs. 3/15). On the other hand, a low mutation rate (1/19) was detected in 19 BG patients. The mutation cosegregated with disease. Besides, three different genotypes in tumors from probands of mutation-positive families were found.</p><p><b>CONCLUSIONS</b>hMSH2 and hMLH1 mutations in Chinese HNPCC families show a wide spectrum. It seems that hMLH1 gene is involved more frequently than hMSH2 gene in Chinese HNPCC families. Different clinical criteria predict mutations with different sensitivities. The Amsterdam Criteria are most sensitive, while Japanese Criteria are highly practical and the Bethesda Guidelines are also practical to some extent. Gene mutations cosegregate with the disease phenotype. Carriers with no symptom in HNPCC families are most vulnerable groups, follow-ups are required for this group to get early diagnosis and to prevent the development of CRCs.</p>