Impact of dose-dense immunochemotherapy on prognosis of germinal center and non germinal center origin of diffuse large B cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is the most common type of non-Hodgkin's lymphoma. Gene-expression profiling in DLCBL has brought insight into the biological heterogeneity of the disease. Two major subgroups have been identified: germinal center B (GCB) cell and non-germinal center (non-GCB). The aim of this study was to define retrospectively by immunohistochemistry the bcell origin of 69 patients treated with R-CHOP14 and to evaluate if dose-dense therapy could improve their clinical outcome. According to immunohistochemistry analysis 28 patients were derived from germinal center and 41 from non-germinal center. After a median period of observation of 46 months (range 3-101 months) the overall survival (OS) was 75% and progression-free survival (PFS) was 53% and no differences were observed according to cell origin. In conclusion, we can point out that intensification could enhance the efficacy of the R-CHOP regimen and improve overall survival in patients with non germinal lymphoma.     

MicroRNA expression distinguishes between germinal center B cell-like and activated B cell-like subtypes of diffuse large B cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is an aggressive malignancy that accounts for nearly 40% of all lymphoid tumors. This heterogeneous disease can be divided into germinal center B cell-like (GCB) and activated B cell-like (ABC) subtypes by gene expression and immunohistochemical profiling. Using microarray analysis on prototypic cell lines, we identified microRNAs (miR-155, miR-21 and miR-221) that were more highly expressed in ABC-type than GCB-type cell lines. These microRNAs were over-expressed in de novo DLBCL (n = 35), transformed DLBCL (n = 14) and follicular center lymphoma cases (n = 27) compared to normal B cells. Consistent with the cell line model, expression levels were higher in DLBCL cases with an ABC-type immunophenotype than those that were GCB-type (p < 0.05). Moreover, using multivariate analysis we found that expression of miR-21 was an independent prognostic indicator in de novo DLBCL (p < 0.05). Interestingly, expression levels of both miR-155 and miR-21 were also higher in nonmalignant ABC than in GCB cells. As we also demonstrate that expression of microRNAs can be measured reliably from routine paraffin-embedded biopsies of more than 8-years-old (p < 0.001), we suggest that microRNAs could be clinically useful molecular markers for DLBCL as well as other cancers.     

弥漫性大B细胞淋巴瘤中Bcl-2/IgH易位的初步研究

目的研究弥漫性大B细胞淋巴瘤中染色体Bcl-2/IgH易位及其与Bcl-2蛋白表达的关系。方法用PCR方法检测42例原发性DLBCL患者的Bcl-2/IgH易位,免疫组化方法检测Bcl-6和CD10的共表达（确认生发中心表型的标志）以及Bcl-2蛋白的表达。结果在42例DLBCL患者中13例为GC亚型病例;Bcl-2/IgH易位检出率为11.9%（5/42）,其中4例属于GC亚型,1例属于非GC亚型;5例易位阳性中3例有Bcl-2蛋白的表达。结论原发性DLBCL的Bcl-2/IgH易位率为11.9%,代表了一类由滤泡中心细胞起源的亚类,Bcl-2/IgH易位与Bcl-2蛋白表达无关。     

Distinctive patterns of BCL6 molecular alterations and their functional consequences in different subgroups of diffuse large B-cell lymphoma.

Gene expression profiling of diffuse large B-cell lymphoma (DLBCL) has revealed biologically and prognostically distinct subgroups: germinal center B-cell-like (GCB), activated B-cell-like (ABC) and primary mediastinal (PM) DLBCL. The BCL6 gene is often translocated and/or mutated in DLBCL. Therefore, we examined the BCL6 molecular alterations in these DLBCL subgroups, and their impact on BCL6 expression and BCL6 target gene repression. BCL6 translocations at the major breakpoint region (MBR) were detected in 25 (18.8%) of 133 DLBCL cases, with a higher frequency in the PM (33%) and ABC (24%) subgroups than in the GCB (10%) subgroup. Translocations at the alternative breakpoint region (ABR) were detected in five (6.4%) of 78 DLBCL cases, with three cases in ABC and one case each in the GCB and the unclassifiable subgroups. The translocated cases involved IgH and non-IgH partners in about equal frequency and were not associated with different levels of BCL6 mRNA and protein expression. BCL6 mutations were detected in 61% of DLBCL cases, with a significantly higher frequency in the GCB and PM subgroups (>70%) than in the ABC subgroup (44%). Exon-1 mutations were mostly observed in the GCB subgroup. The repression of known BCL6 target genes correlated with the level of BCL6 mRNA and protein expression in GCB and ABC subgroups but not with BCL6 translocation and intronic mutations. No clear inverse correlation between BCL6 expression and p53 expression was observed. Patients with higher BCL6 mRNA or protein expression had a significantly better overall survival. The biological role of BCL6 in translocated cases where repression of known target genes is not demonstrated is intriguing and warrants further investigation.     

bcl-2 translocation in Japanese B cell lymphoma: novel bcl-2 translocation with immunoglobulin heavy chain diversity segment

Breakpoints of a lymphoma case with bcl-2 gene rearrangement that did not show comigration of immunoglobulin (Ig) heavy chain joining (JH) fragment were cloned. Sequence analysis revealed that the translocation broke the 3' side of the Ig heavy chain diversity (DH) segment at the heptamer recombination signal and each end was ligated to the bcl-2 locus. Since Southern blot demonstrated that both alleles of JH were rearranged, this translocation was suggested to have occurred at the step of VH-DH, or DH-DHJH recombination, one step later than that of DH-JH recombination where the common pattern of bcl-2 rearrangement generally occurs. Cases that showed comigration with JH fragment were also studied by polymerase chain reaction with 5' bcl-2 oligomer and 3' JH consensus anti-sense oligomer since it has been demonstrated that bcl-2 translocation at the major breakpoint clustering region (mbr) in American cases clusters within an about 150 bp region in the mbr. The results demonstrated that four out of five cases studied were amplified, indicating that the same clustering mechanism exists for Japanese cases. The present study, together with our previous report on Ig kappa-bcl-2, indicated that bcl-2 translocation in Japanese B cell lymphomas might occur at a later stage of B cell development, as compared with that in American cases. Less involvement of bcl-2 in Japanese B cell lymphoma may also be in part explainable by low susceptibility to bcl-2 rearrangement at the step of DH-JH recombination.     

MYC translocation and/or BCL 2 protein expression are associated with poor prognosis in diffuse large B‐cell lymphoma

Genomic alterations and protein expression levels have been established as prognostic factors for survival in patients with diffuse large B‐cell lymphoma (DLBCL). In particular, double‐hit DLBCL (DHL), which exhibits translocations in MYC and BCL2 and/or BCL6, is known to be associated with a poor prognosis. However, the clinical significance of gene alterations and protein expression levels for MYC, B‐cell lymphoma (BCL)2, and BCL6 are unclear. In this study, we analyzed 61 adult patients diagnosed with DLBCL without DHL, who were treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone, or similar regimens. There were no differences in the distribution of MYC expression rates among the different MYC gene statuses. In log–rank tests, MYC translocation was a prognostic factor for overall survival (OS; P = 0.011), whereas BCL2 and BCL6 translocation were not prognostic indicators (P = 0.999 and P = 0.925, respectively). Although the expression levels of MYC and BCL6 were not significantly associated with OS, the expression of BCL2 was a prognostic factor for OS (P = 0.027). Furthermore, copy number gains in the MYC, BCL2, and BCL6 genes did not affect OS. MYC translocation (hazard ratio, 4.769; range, 1.518–14.98; P = 0.007) and BCL2 protein expression (hazard ratio, 3.072; range, 1.002–9.413; P = 0.049) were independent prognostic factors for survival in multivariate analyses. In conclusion, MYC translocation and BCL2 expression may need to be investigated at the initial diagnosis to predict prognosis in patients with DLBCL.     

Prostate cancer stem cells and their potential roles in metastasis

Most solid tumors have now been reported to contain stem cell-like cells called cancer stem cells (CSCs). These cells are endowed with high tumorigenic capacity and may be the cells that drive tumor formation, maintain tumor homeostasis, and mediate tumor metastasis. Since these self-renewing cancer cells may be the sole population to develop a primary tumor, it is predicted that CSCs may also represent the lethal seeds of metastasis, as supported by a flurry of recent studies on the relationship between CSCs and metastasis. Herein, we summarize current knowledge of stem/progenitor cells and CSCs, especially in the context of normal human prostate and prostate cancer. We further update the recently gained knowledge on the involvement of CSCs in metastasis. We also discuss the fundamental influence of tumor microenvironment on the manifestation of CSCs and metastasis. Finally, we discuss the clinical implication of CSC-based therapy.     

Dysregulated CXCR4 expression promotes lymphoma cell survival and independently predicts disease progression in germinal center B-cell-like diffuse large B-cell lymphoma

Abnormal expression of the chemokine receptor CXCR4 plays an essential role in tumor cell dissemination and disease progression. However, the significance of CXCR4 overexpression in de novo diffuse large B cell lymphoma (DLBCL) is unknown. In 743 patients with de novo diffuse large B cell lymphoma (DLBCL) who received standard Rituximab-CHOP immunochemotherapy, we assessed the expression of CXCR4 and dissected its prognostic significance in various DLBCL subsets. Our results showed that CXCR4⁺ patients was associated with male, bulky tumor, high Ki-67 index, activated B-cell-like (ABC) subtype, and Myc, Bcl-2 or p53 overexpression. Moreover, CXCR4⁺ was an independent factor predicting poorer progression-free survival in germinal-center B-cell-like (GCB)-DLBCL, but not in ABC-DLBCL; and in patients with an IPI of ≤2, but not in those with an IPI>2. The lack of prognostic significance of CXCR4 in ABC-DLBCL was likely due to the activation of p53 tumor suppressor attenuating CXCR4 signaling. Furthermore, concurrent CXCR4⁺ and BCL2 translocation showed dismal outcomes resembling but independent of MYC/BCL2 double-hit DLBCL. Gene expression profiling suggested that alterations in the tumor microenvironment and immune responses, increased tumor proliferation and survival, and the dissemination of CXCR4⁺ tumor cells to distant organs or tissues were underlying molecular mechanisms responsible for the CXCR4⁺ associated poor prognosis.     

Regulatory roles of cell surface sialylation in sphingolipid-induced cell death in human B cell lymphoma

Sphingolipid metabolites are important regulators of cell growth and death. In the present study, we examined the function of cell surface sialic acid in exogenous sphingosine-1-phosphate (S-1-P) or sphingosine-induced cell death. HBL-2 human diffuse large B cell lymphoma cells were incubated with or without Vibrio Cholerae neuraminidase followed by S-1-P or sphingosine. Flow cytometric analysis using Limax flavus agglutinin, a sialic acid-specific lectin, showed that sialylated glycoconjugates are present on the surface of HBL-2 cells and that they were removed by neuraminidase. In addition, the pretreatment with neuraminidase enhanced S-1-P- and sphingosine-induced cell death, an effect that was not dependent on caspase activation. Furthermore, the cell death induced by S-1-P and sphingosine was morphologically distinct from apoptosis. We further examined S-1-P-induced cell death in two clones of HBL-8 Burkitt lymphoma cells with different amounts of cell surface sialic acid. Clone 3G3, which is hypersialylated, was less sensitive to S-1-P than the 3D2 clone, which is hyposialylated, suggesting that the extent of surface sialylation influences the sensitivity to S-1-P. In conclusion, S-1-P and sphingosine induce cell death, and the sensitivity of human B lymphoma cells to these agents appears to depend on the amount of sialic acid on their cell surfaces.     

Embryonic stem cell miRNAs and their roles in development and disease

MicroRNAs have emerged as important modulators of gene expression. Both during development and disease, regulation by miRNAs controls the choice between self-renewal and differentiation, survival and apoptosis and dictates how cells respond to external stimuli. In mouse pluripotent embryonic stem cells, a surprisingly small set of miRNAs, encoded by four polycistronic genes is at the center of such decisions. miR-290-295, miR-302-367, miR-17-92 and miR-106b-25 encode for miRNAs with highly related sequences that seem to control largely overlapping gene sets. Recent studies have highlighted the importance of these miRNAs in the maintenance of 'stemness' and regulation of normal development and have linked the deregulation of their expression to a variety of human diseases.     

Establishment of a human herpes virus-8-negative malignant effusion lymphoma cell line (STR-428) carrying concurrent translocations of BCL2 and c-MYC genes

A new cell line, STR-428 was established from ascites tumor cells of a malignant effusion lymphoma patient without human herpes virus-8 (HHV-8) infection. STR-428 cells showed an immunophenotype of mature B-cells and produced few cytokines related to lymphomatous effusion. Karyotypic and genetic analysis revealed complex translocations including t(14;18)(q32;q21) effecting IgH/BCL2 and der(8)t(3;8)(q27;q24) involving c-MYC. STR-428 represents a unique, B-cell lymphoma cell line carrying concurrent rearrangement of BCL2 and c-MYC genes with features distinct from those of HHV-8-related primary effusion lymphoma. This cell line may be a valuable tool, other than HHV-8, to investigate the pathogenesis of primary lymphomatous effusion.     

Amplified and rearranged bcl-2 gene in two lymphoma cell lines, FL-218 and FL-318, carrying a 14;18 translocation

Two human B-cell lines carrying a 14;18 chromosome translocation [t(14;18)(q32;q21)], designated FL-218 and FL-318, were established from effusion cells of two Japanese patients manifesting the transformed histology of follicular lymphoma. The FL-218 and FL-318 cell lines were composed of cells in the hyperdiploid range, which had two and three or four 18q- chromosomes, respectively. These 18q- chromosomes were not distinguishable from an 18q- chromosome derived from t(14;18) since they exhibited the same banding pattern. Southern blot analysis revealed that in both cell lines, breakage of the bcl-2 gene occurred within the major breakpoint cluster region and the truncated gene juxtaposed to an immunoglobulin heavy chain gene locus. The autoradiographic intensity of the retained fragment each on 18q- chromosome was more enhanced than that of the translocated fragment on 14q+ chromosome. These findings suggest that the extra 18q- chromosome found in t(14;18)-positive cancer does not arise from de novo independent t(14;18) but from duplication of a preexisting 18q- chromosome.     

The regulatory roles of cell surface sialylation and N-glycans in human B cell lymphoma cell adhesion to galectin-1

Surface sialylation and glycosylation of tumor cells is known to affect various biological phenomena. In the present study, we analyzed the regulatory roles of cell surface sialylation in cell adhesion to galectin-1 in the human diffuse large B cell lymphoma (DLBCL) cell line, HBL-2, and Burkitt's lymphoma cell line, HBL-8. Vibrio cholerae neuraminidase treatment enhanced HBL-2 cell adhesion to galectin-1, suggesting that sialic acid inhibits HBL-2 cell adhesion to galectin-1. The data from employing two different neuraminidases, Vibrio cholerae and Newcastle disease virus neuraminidase, showed that alpha2,6-linked sialic acid plays an important role in the inhibition of HBL-2 cell adhesion to galectin-1. In addition, neuraminidase treatment enhanced the cell adhesion to galectin-1 much more with the highly sialylated HBL-8 3G3 clone than with the hyposialylated HBL-8 3D2 clone. Flow cytometric analysis revealed the expression of partially sialylated L-PHA reactive oligosaccharides on the surfaces of HBL-2 cells. Swainsonine (SW) treatment also enhanced HBL-2 cell adhesion to galectin-1. These data indicate that SW treatment decreased sialylated L-PHA reactive oligosaccharides resulting in cell surface desialylation and leading to enhancement of cell adhesion to galectin-1. In conclusion, alteration of cell surface sialylation or N-glycan expression regulates cell adhesion to galectin-1 in human malignant lymphoma.