The development of gastric mucosaassociated lymphoid tissue (MALT) lymphoma is a multistep process and can be clinico-pathologically divided into Helicobacter pylori-associated gastritis, lowgrade tumors, and high-grade tumors. The molecular events underlying this progression are largely unknown. However, identification of the genes involved in MALT lymphoma-specific t(11;18)(q21; q21) and t(1;14)(p22;q32) has provided fresh insights into the pathogenesis of this disease. T(11;18)(q21;q21) results in a chimeric transcript between the API2 and the MALT1 genes, whereas t(1;14) (p22;q32) causes aberrant nuclear BCL10 expression. Significantly, nuclear BCL10 expression also occurs frequently in MALT lymphomas without t(1;14)(p22; q32), suggesting an important role for BCL10 in lymphoma development. Thirtythree cases of H pylori gastritis, 72 MALT lymphomas, and 11 mucosal diffuse large B-cell lymphomas (DLBCL) were screened for t(11;18)(q21;q21) by reverse transcription-polymerase chain reaction followed by sequencing. BCL10 expression in lymphoma cases was examined by immunohistochemistry. The API2-MALT1 fusion transcript was not detected in H pylori gastritis and mucosal DLBCL but was found in 25 of 72 (35%) MALT lymphomas of various sites. Nuclear BCL10 expression was seen in 28 of 53 (53%) of MALT lymphomas. Of the gastric cases, the largest group studied, the frequency of both t(11;18)(q21;q21) and nuclear BCL10 expression was significantly higher in tumors that showed dissemination to local lymph nodes or distal sites (14 of 18 ‫؍‬ 78% and 14 of 15 ‫؍‬ 93%, respectively) than those confined to the stomach (3 of 29 ‫؍‬ 10% and 10 of 26 ‫؍‬ 38%). Furthermore, t(11;18)(q21;q21) closely correlated with BCL10 nuclear expression. These results indicate that both t(11;18)(q21;q21) and BCL10 nuclear expression are associated with advanced MALT lymphoma and that their oncogenic activities may be related to each other. IntroductionThe development of mucosa-associated lymphoid tissue (MALT) lymphoma is a multistage process. 1 This is best understood in gastric MALT lymphoma, the most common form. Typically, low-grade gastric MALT lymphoma arises from mucosal lymphoid tissue that is acquired usually as a reaction to Helicobacter pylori infection. 2,3 Low-grade MALT lymphoma is initially confined to the gastric mucosa, and its growth depends critically on the contact help of H pylori-specific intratumoral T cells; therefore, it responds favorably to H pylori eradication therapy. [4][5][6] However, when the lymphoma invades the deep layers of the gastric wall and disseminates to local lymph nodes and distal sites, the tumor loses its dependence on H pylori-specific T cells and is no longer sensitive to H pylori eradication therapy. 7-9 Finally, low-grade gastric MALT lymphoma may transform into a more aggressive diffuse large B-cell lymphoma (DLBCL). 10,11 Direct 12-14 and indirect antigen stimulation 4,5 and several genetic factors, including genetic instability, 15 trisomy 3, 16 p53 mutation/LOH, 17 p16 deletion, 18 t(1;...

Infectious agents play a critical role in MALT lymphoma development. Studies from Italy showed Chlamydia psittaci infection in 87% of ocular adnexal MALT lymphomas and complete or partial regression of the lymphoma after C. psittaci eradication in four of nine cases. However, C. psittaci was not demonstrated in ocular adnexal MALT lymphomas from the USA. This study was thus designed to investigate further the role of C. psittaci, and other infectious agents commonly associated with chronic eye disease, in the development of ocular adnexal MALT lymphoma. The presence of C. psittaci, C. trachomatis, C. pneumoniae, herpes simplex virus 1 and 2 (HSV1, HSV2), and adenovirus 8 and 19 (ADV8, ADV19) was assessed separately by polymerase chain reaction in 142 ocular adnexal MALT lymphomas, 53 non-marginal zone lymphomas, and 51 ocular adnexal biopsies without a lymphoproliferative disorder (LPD), from six geographical regions. C. psittaci was detected at similar low frequencies in non-LPD and non-marginal zone lymphoma groups from different geographical regions (0-14%). Overall, the prevalence of C. psittaci was significantly higher in MALT lymphomas (22%) than in non-LPD (10%, p=0.042) and non-marginal zone lymphoma cases (9%, p=0.033). However, the prevalence of C. psittaci infection in MALT lymphoma showed marked variation among the six geographical regions examined, being most frequent in Germany (47%), followed by the East Coast of the USA (35%) and the Netherlands (29%), but relatively low in Italy (13%), the UK (12%), and Southern China (11%). No significant differences in the detection of C. pneumoniae, C. trachomatis, HSV1, HSV2, ADV8, and ADV19 were found between lymphomas and controls from different geographical regions. In conclusion, our results show that C. psittaci, but not C. pneumoniae, C. trachomatis, HSV1, HSV2, ADV8 or ADV19, is associated with ocular adnexal MALT lymphoma and that this association is variable in different geographical areas.

BackgroundImproved detection methods for diagnosis of malignant pleural mesothelioma (MPM) are essential for early and reliable detection as well as treatment. Since recent data point to abnormal levels of microRNAs (miRNAs) in tumors, we hypothesized that a profile of deregulated miRNAs may be a marker of MPM and that the levels of specific miRNAs may be used for monitoring its progress.Methods and ResultsmiRNAs isolated from fresh-frozen biopsies of MPM patients were tested for the expression of 88 types of miRNA involved in cancerogenesis. Most of the tested miRNAs were downregulated in the malignant tissues compared with the normal tissues. Of eight significantly downregulated, three miRNAs were assayed in cancerous tissue and adjacent non-cancerous tissue sample pairs collected from 27 formalin-fixed, paraffin-embedded MPM tissues by quantitative RT-PCR. Among the miRNAs tested, only miR-126 significantly remained downregulated in the malignant tissues. Furthermore, the performance of the selected miR-126 as biomarker was evaluated in serum samples of asbestos-exposed subjects and MPM patients and compared with controls. MiR-126 was not affected by asbestos exposure, whereas it was found strongly associated with VEGF serum levels. Levels of miR-126 in serum, and its levels in patients' serum in association with a specific marker of MPM, SMRPs, correlate with subjects at high risk to develop MPM.Conclusions and SignificanceWe propose miR-126, in association with SMRPs, as a marker for early detection of MPM. The identification of tumor biomarkers used alone or, in particular, in combination could greatly facilitate the surveillance procedure for cohorts of subjects exposed to asbestos.

Mucosa-associated lymphoid tissue (MALT) lymphoma is specifically associated with t(11;18)(q21;q21), t(1;14)(p22;q32) and t(14;18)(q32;q21). t(11;18)(q21;q21) fuses the N-terminus of the API2 gene to the C-terminus of the MALT1 gene and generates a functional API2-MALT1 product. t(1;14)(p22;q32) and t(14;18)(q32;q21) bring the BCL10 and MALT1 genes respectively to the IGH locus and deregulate their expression. The oncogenic activity of the three chromosomal translocations is linked by the physiological role of BCL10 and MALT1 in antigen receptor-mediated NFkappaB activation. In this study, MALT1 and BCL10 expression was examined in normal lymphoid tissues and 423 cases of MALT lymphoma from eight sites, and their expression was correlated with the above translocations, which were detected by molecular and molecular cytogenetic methods. In normal B-cell follicles, both MALT1 and BCL10 were expressed predominantly in the cytoplasm, high in centroblasts, moderate in centrocytes and weak/negative in mantle zone B-cells. In MALT lymphoma, MALT1 and BCL10 expression varied among cases with different chromosomal translocations. In 9/9 MALT lymphomas with t(14;18)(q32;q21), tumour cells showed strong homogeneous cytoplasmic expression of both MALT1 and BCL10. In 12/12 cases with evidence of t(1;14)(p22;q32) or variants, tumour cells expressed MALT1 weakly in the cytoplasm but BCL10 strongly in the nuclei. In all 67 MALT lymphomas with t(11;18)(q21;q21), tumour cells expressed weak cytoplasmic MALT1 and moderate nuclear BCL10. In MALT lymphomas without the above translocations, both MALT1 and BCL10, in general, were expressed weakly in the cytoplasm. Real-time quantitative RT-PCR showed a good correlation between MALT1 and BCL10 mRNA expression and underlining genetic changes, with t(14;18)(q32;q21)- and t(1;14)(p22;q32)-positive cases displaying the highest MALT1 and BCL10 mRNA expression respectively. These results show that MALT1 expression pattern is identical to that of BCL10 in normal lymphoid tissues but varies in MALT lymphomas, with high cytoplasmic expression of both MALT1 and BCL10 characterizing those with t(14;18)(q32;q21).