BCL-6 mRNA expression in higher grade transformation of follicle center lymphoma: correlation with somatic mutations in the 5' regulatory region of the BCL-6 gene.

Follicle center lymphoma (FCL) is an indolent low-grade B cell non-Hodgkin's lymphoma (NHL) that frequently transforms to aggressive diffuse large B cell lymphoma (DLBCL). Histological transformation of FCL is commonly associated with accumulation of secondary genetic alterations. The BCL-6 gene is commonly implicated in the pathogenesis of DLBCL and its expression may be altered by clonal rearrangements and somatic point mutations in its 5' non-translated regulatory region. Recently, somatic mutations of the BCL-6 gene were associated with the transformation process. Here, we examined BCL-6 mRNA expression and BCL-6 mutations in paired biopsies from the same patients obtained at the time of FCL diagnosis and after transformation. BCL-6 mRNA expression markedly increased upon transformation (1.9- to 4.8-fold) in three cases, remained unchanged in one case and decreased compared to the diagnosis FCL specimens in four cases. The three specimens that demonstrated an increase in the BCL-6 mRNA expression upon transformation harbored BCL-6 gene mutations in the 5' region of the first intron that overlapped with the previously reported negative regulatory region of the gene. Accumulation of new mutations in this region was not observed in DLBCL biopsies in which the BCL-6 mRNA expression did not increase. The present study demonstrates that although BCL-6 gene mutations do accumulate during the transformation process and, depending on their location within the first intron, may deregulate BCL-6 mRNA expression, increase in BCL-6 mRNA expression is not uniformly required for transformation from FCL to DLBCL.     

Genetic instability is associated with histological transformation of follicle center lymphoma.

Follicle center lymphoma (FCL) is an indolent B cell non-Hodgkin's lymphoma (NHL) characterized genetically by the t(14;18) translocation. Histological transformation and clinical progression of FCLs are frequently associated with secondary genetic alterations at both nucleic acid and chromosomal levels. To determine the type and pattern of genomic instability occurring in histological transformation of FCLs and the role of DNA mismatch repair defects in this procedure, we have performed microsatellite analysis, comparative genomic hybridization (CGH) and mutational analysis of hMLH1 and hMSH2 genes on serial biopsy specimens from patients with FCL transformed to diffuse large cell lymphoma (DLCL). Paired biopsy samples of eight patients were analyzed for microsatellite instability and structural alterations for hMLH1 and hMSH2 genes, and tumor samples of five patients were subjected to CGH analysis. A high level of microsatellite instability was associated with histological transformation of two cases of FCL, but no mutations of the hMLH1 and hMSH2 genes were detected in any of the lymphoma samples. In the five cases subjected to CGH analysis, the histological transformation of FCLs was associated with genomic imbalances at 21 chromosomal regions. The genomic abnormalities found were rather heterogeneous and none of the genetic changes were overrepresented in the transformed DLCLs. These data suggest that histological transformation of FCLs to DLCL is frequently associated with genome wide instability at both nucleic acid and chromosomal levels, although mutations of the hMSH1 and hMLH2 genes are not involved in this process.     

Primary cutaneous follicle center lymphoma associated with alopecia areata

We report a patient who presented simultaneously with primary cutaneous follicle center lymphoma (PCFCL) of the face and scalp and alopecia areata of the scalp and beard bearing a clonal T-cell receptor gene rearrangement. To our knowledge, alopecia areata has not been previously reported in association with PCFCL. Both lesions regressed with topical imiquimod and systemic steroids, which suggests an inter-relationship in this case between the clonal B-cell and T-cell populations in driving outgrowth of these lesions.     

Follicle center lymphoma is associated with significantly elevated levels of BCL-6 expression among lymphoma subtypes, independent of chromosome 3q27 rearrangements.

The BCL-6 gene, located on chromosome 3q27, is implicated in the normal germinal center formation and is frequently rearranged in a wide spectrum of lymphomas. However the links between genetic alterations and expression of the gene are not clearly determined. We established a quantitative RT-PCR assay based on TaqMan technology to quantify BCL-6 mRNA expression in different subtypes of lymphomas and to compare the level of expression in lymphomas characterized by the presence or absence of BCL-6 translocation. Total RNA was extracted from 105 nodes biopsies (35 diffuse large B cell lymphomas (DLBCL); 26 follicle center lymphomas (FCL); 7 marginal zone lymphomas (MZL); 6 mantle cell lymphomas (MCL); 6 chronic lymphocytic leukemia (CLL); 5 T cell lymphomas (TCL); 7 classical Hodgkin diseases (HD); 6 nodal metastasis (NM); and 7 reactive hyperplasia (RH)). BCL-6 gene rearrangement was assessed by Southern blot analysis in 75% of 3q27(+) DLBCL (n = 20) cases and 67% of 3q27(+) cases (n = 10). The highest level of relative BCL-6 expression was observed in FCL (9.12 +/- 7.28) comparatively to the other lymphoma subtypes including DLBCL (2.53 +/- 1.82; P < 0.001), MCL (1.23 +/- 0.73), MZL (1.49 +/- 1.3), HD (1.60 +/- 1.00), TCL (1.75 +/- 1.64), but also RH (3.91 +/- 3.12) or NM (1.95 +/- 2.6). Among the 26 FCL cases, we observed a lower expression in grade 3 (n = 8) than in grade 1/2 (P < 0.001). Conversely, we failed to show any difference between 3q27(+) DLBCL and 3q27(-)DLBCL cases (P = 0.42). Paradoxically BCL-6 expression in 3q27(+) FCL (n = 10) was significantly lower than in 3q27(-) FCL cases (P = 0.035). Finally, this study showed that BCL-6 expression in lymphoma is largely independent of chromosome 3q27 rearrangement and is more related to the histological subtype. Clinical implication and alternative deregulation pathways of BCL-6 expression remain to be determined.     

Mutation of the ATM gene is not involved in the pathogenesis of either follicle center lymphoma or its transformation to higher-grade lymphoma

Loss of function of the ataxia-telangiectasia mutated (ATM) gene, located on human chromosome 11q22-23, is the cause of ataxia-telangiectasia (A-T), which is associated with an extremely high risk for lymphoma. Abnormalities in 11q22-23, including deletions and mutations of the ATM gene, have been reported in T-cell prolymphocytic leukemias, B-CLL and in mantle cell lymphoma. In a survey of gene expression in follicle center lymphomas (FCL) and diffuse large B-cell lymphomas (DLBCL), almost all FCL expressed significant levels of ATM and the majority of DLBCL expressed low levels of ATM. This finding raised the possibility that the transformation of some FCL to DLBCL might be associated with inactivation of the ATM gene. Therefore, we analyzed biopsy specimens of 17 patients with FCL obtained at the time of diagnosis, four subsequent biopsies obtained at the time of FCL relapse and seven subsequent biopsies at the time of transformation to DLBCL. A comprehensive analysis of the ATM gene was performed by denaturing high performance liquid chromatography and sequencing. The analysis covered all of the 66 exons including the 9168 base pairs of ATM coding sequence as well as 16,676 base pairs of non-coding sequence. Twenty-eight known polymorphisms and rare sequence variants were observed, but no classic A-T mutations were detected. In 11 tumors, both tumor B-cells and normal T-cells were sorted for separate examination, and in each case, polymorphisms and rare variants were present in both tumor and normal cells. No new ATM gene mutations were associated with transformation from FCL to DLBCL. Thus, ATM gene mutations do not play a pivotal role either in the pathogenesis of FCL or in its transformation to DLBCL.     

BCL-6与弥漫性大B细胞淋巴瘤的相关性

弥漫性大B细胞淋巴瘤(DLBCL)是非霍奇金淋巴瘤中发病最多的一型,与BCL-6基因高度相关.BCL-6主要分布于生发中心及生发中心起源的淋巴瘤中,在DLBCL中易发生易位、突变、缺失从而导致表达失调,作用于与细胞活化、分化、周期、凋亡相关的基因,使细胞处于快速增殖、幼稚状态.BCL-6对DLBCL预后的意义尚有争议,不同的统计数据得出了不同结论.     

A polymorphism in the CYP17 gene is associated with prostate cancer risk

CYP17 encodes the enzyme cytochrome P-450c17 alpha, which mediates both 17 alpha-hydroxylase and 17,20-lyase in the steroid biosynthesis pathway. A polymorphism in the 5; promoter region of the CYP17 gene has been described. Steroid hormones, especially androgens, are believed to play a key role in the etiology of prostate cancer. Therefore, polymorphisms in genes involved in the androgen metabolism may affect the risk of prostate cancer. We conducted a case-control study of 63 patients with untreated histologically proven prostate cancer and 126 age-matched control men with benign prostatic hyperplasia (BPH) to determine whether a polymorphism in the CYP17 gene is associated with prostate cancer risk. This polymorphism was investigated by PCR/RFLP using DNA from lymphocytes. The transition (T-->C) in the risk allele (A2) creates a new recognition site for the restriction enzyme MspAI, which permits designation of the wildtype (A1) and the risk allele (A2). The prevalence of the A2/A2 genotype was significantly higher (P = 0.03) in the cancer group (23.8%) than in the BPH control group (9.5%). We found an increased risk in men carrying 2 A2 alleles (OR = 2.80, 95%CI = 1.02-77.76). For carrier with at least 1 A2 allele, the OR was 0.90 (95%CI = 0.43-1.89). After stratification by median age (66 years) at time of diagnosis, a marked increased risk was found in carriers of the A2/A2 genotype older than 66 years (OR = 8.93, 95%CI = 1.78-49.19, P = 0.01). Although the sample size is rather small and the controls are BPH patients, our results suggest that the CYP17A2/A2 genotype may be a biomarker for prostate cancer risk, especially for older men.     

A novel single nucleotide polymorphism in ERCC6 gene is associated with oral cancer susceptibility in Taiwanese patients

The DNA repair gene ERCC6, an important caretaker of the overall genome stability, is thought to play a role in the development of human malignancy. However, the polymorphic variants of ERCC6, has never been reported about their association with oral cancer susceptibility. In this hospital-based case-control study, the association of ERCC6 codon 399, 1097 and 1413 polymorphisms with oral cancer risk in a Central Taiwanese population was first investigated. In total, 292 patients with oral cancer and 290 age- and gender-matched healthy controls recruited from the China Medical Hospital in Central Taiwan were genotyped. We found a significant different distribution in the frequency of the ERCC6 codon 399 genotypes, but not the ERCC6 codon 1097 or 1413 genotypes, between the oral cancer and control groups. Those who had homozygous A/A or heterozygous A/G at ERCC6 codon 399 showed a 1.82- and 1.22-fold (95% confidence interval=1.19-2.79 and 0.83-1.78, respectively) increased risk of oral cancer compared to those with G/G. As for ERCC6 codon 1097 or 1413, there was no difference in distribution between the oral cancer and control groups. Gene-environment interactions with smoking and betel quid chewing, but not alcohol drinking, were significant for ERCC6 polymorphisms. ERCC6 codon 399, G/A+A/A ever user groups exhibited an increased risk of 2.36 (95% CI=1.36-4.10) for smoking and 2.72 (95% CI=1.31-5.63) for betel quid chewing. Our results firstly suggest that the heterozygous and homozygous A allele of the ERCC6 codon 399 may be associated with the development of oral cancer and may be a novel useful marker for primary prevention and anticancer intervention.     

A polymorphism in the CYP17 gene is associated with male breast cancer.

The CYP17 gene codes for the cytochrome P450c17alpha enzyme that is involved in the synthesis of oestrogens. This case-control study from the South East of Scotland shows that a polymorphism of the CYP17 gene is associated with an increased risk of male breast cancer.     

Protein expression of B-cell lymphoma gene 6 (BCL-6) in invasive breast cancer is associated with cyclin D1 and hypoxia-inducible factor-1alpha (HIF-1alpha)

B-cell lymphoma gene (BCL-6) upregulation contributes to immortalization of mouse embryo fibroblast and primary B cells via upregulation of cyclin D1. As cyclin D1 overexpression is a common phenomenon in different cancers, BCL-6 protein overexpression may not be restricted to lymphomas. In this study, expression of BCL-6 was investigated by immunohistochemistry on paraffin-embedded specimens from 150 breast cancer patients and 10 specimens of normal breast tissue. The results showed BCL-6 overexpression (> or =10% of cells) in 24/150 (16%) breast cancer patients, whereas in normal breast low expression (<1%) of BCL-6 was observed. In linear regression analysis BCL-6 expression was associated with cyclin D1 (r=0.197, P=0.016). Further, in chi2 analyses, BCL-6-positivity was associated with overexpression of p53 (P=0.016), and hypoxia-inducible factor-1alpha (P<0.001). Involvement of BCL-6 in breast carcinogenesis is further underscored by comparative genomic hybridization analysis that showed gains at the BCL-6 locus (3q27) in 14/86 (16%) breast cancer tissues. The cases with amplification in BCL-6 showed an increased (25%) incidence of BCL-6 protein overexpression. Thus, this study is the first to show that BCL-6 oncogene activation plays a role in cancers other than lymphomas.     

Single nucleotide polymorphism in 5'-flanking region of BCL6 is not associated with increased risk of non-Hodgkin's lymphoma

Mutations in the 5'-regulatory region of BCL6 were suggested to play a role in non-Hodgkin's lymphoma (NHL) progression and in the transformation of follicular lymphoma to more aggressive diffuse large B-cell type. The aim of this study was to explore association between polymorphism G397C in the 5'-region of BCL6 and both incidence and progression of NHL in 154 NHL cases and 362 controls. Neither frequencies of the rare BCL6 allele 397C nor particular genotypes differed significantly between NHL cases and controls. There was no significant association of histological type of NHL and clinical characteristics with this polymorphism.     

A microsatellite polymorphism in the heme oxygenase-1 gene promoter is associated with risk for melanoma

Heme oxygenase-1 (HO-1) has been demonstrated to play an important role in the regulation of signaling systems, which are involved in the control of cell cycle progression and apoptosis. Recently, a (GT)n dinucleotide repeat polymorphism in the HO-1 promoter was shown to modulate HO-1 gene expression. Short (<25 GT) repeats are associated with an increased HO-1 upregulation after stimulation than are longer repeats. Malignant melanoma (MM) is the most serious cutaneous malignancy with high tendency to aggressive growth and resistance to apoptosis. Therefore, we sought to study the influence of this polymorphism on the progression of MM. We determined the HO-1 promoter genotype in 152 patients with MM and 398 healthy controls and studied their association in regard to susceptibility to MM, Breslow thickness and disease-free survival. In our study, the homozygous short allele with <25 (GT)n repeats (S/S) was found more frequently in the melanoma group compared to the healthy control population (21 and 12%, respectively). The calculated risk for acquiring primary MM in S/S carriers was 2-fold higher compared to those with L-allele types (95% confidence interval: 1.2-2.4, p = 0.03). Additionally, the S/S genotype was significantly associated with primary tumors with deeper Breslow thickness compared to L-allele (>25 repeats) carriers (mean Breslow thickness: 4.0 +/- 2.9 mm versus 3.1 +/- 1.7 mm, p = 0.03). These data suggest that HO-1 might render a higher risk for MM in S/S genotype individuals and could represent an important candidate gene in the pathogenesis and growth of malignant melanoma.     

The expression of IgM is helpful in the differentiation of primary cutaneous diffuse large B cell lymphoma and follicle center lymphoma

Diffuse large B-cell infiltration of the skin includes mainly primary cutaneous follicle center lymphoma (PCFCL) with diffuse architecture and diffuse large B cell lymphoma (PCDLBCL), leg type. Differentiation of these lymphomas on morphology may be troublesome. Immunohistochemistry panel, including CD20, CD79a, bcl-6, bcl-2, MUM-1, FOX-P1 is mandatory. However, in minority of cases, these markers would not suffice. In order to search the value of another marker, IgM, 30 cases of PCFCL and 10 cases of PCDLBCL, leg type were included in the study. As suggested in a recent literature, our study denoted that expression of IgM was useful as an additional tool for differentiation.     

A polymorphism in Werner syndrome gene is associated with breast cancer susceptibility in Chinese women

RecQ helicases play a central role in maintaining genome stability and may interact with some important cancer-related proteins such as BRCA1. Mutations of the human RecQ helicase genes WRN and BLM lead to rare autosomal recessive disorders, Werner and Bloom syndromes, which are associated with premature aging and cancer predisposition, including breast cancer. In this case–control study of 1,004 breast cancer cases and 1,008 controls, we tested the hypothesis that non-conservative amino acid exchanges in WRN (leu1074Phe), BLM (Met298Thr) and BRCA1 (Pro871Leu) are independently or jointly associated with the risk of breast cancer in Chinese women. We found that the variant genotype of WRN Leu1074Phe was associated with a 1.36-fold significantly increased risk of breast cancer (OR = 1.36, 95% CI = 1.06–1.74). Moreover, a significant gene–environment interaction was evident between WRN leu1074Phe and age at menarche (P _int = 0.02). Subjects carrying Phe/Phe genotype and with earlier age at menarche had 3.58-fold increased risk of breast cancer (OR = 3.58, 95% CI = 2.54–5.05). However, we did not find the significant main effect of polymorphisms in BLM and BRCA1 and also no locus–locus interactions were identified between WRN, BLM and BRCA1. These findings indicate that WRN leu1074Phe variant may contribute to the susceptibility of breast cancer in Chinese women.     

Analysis of FAS (CD95) gene mutations in higher-grade transformation of follicle center lymphoma

The FAS antigen (CD95/APO-1) is suggested to be a tumor suppressor gene since mice and patients with congenital FAS mutations are prone to B cell lymphomas and somatic FAS mutations are described in hematological and solid tumors. Indeed, mutations of the FAS antigen have been found in 13% of multiple myelomas, 6% of follicle center lymphomas (FCL) and 21% of diffuse large B-cell lymphomas (DLBCL). To assess the possible role of FAS mutations in higher-grade transformation of FCL, biopsy specimens from 16 FCL patients were analyzed by denaturing high performance liquid chromatography and direct sequencing. Overall, 17 biopsy specimens obtained at the time of FCL diagnosis (2 biopsy specimens from one patient), 4 sequential biopsies obtained at the time of FCL relapse and 14 sequential biopsies from the time of morphologic transformation to DLBCL were evaluated. Ten polymorphisms were detected, only 4 of which have been reported previously. Nine of the polymorphisms occurred in non-translated regions, while one silent mutation was located in exon 7. Neither loss of heterozygosity nor occurrence of new mutations was observed upon higher-grade transformation of FCL to DLBCL.     

PRKCH gene polymorphism is associated with the risk of severe gastric atrophy

Background  

Individuals infected with Helicobacter pylori do not necessarily develop gastric atrophy (GA) and gastric cancer (GC). Several factors, including genetic polymorphism, can regulate the development of GA and GC. A G/A single nucleotide polymorphism (rs3783799) of the PRKCH gene, which encodes the η isozyme of protein kinase C (PKCη), has been reported to be a tag single nucleotide polymorphism (SNP) of the PRKCH gene linked to a functional 1425G/A SNP in exon 9 (rs2230500). To elucidate its applicability in the development of GA and GC, this study aimed to investigate the associations of the PRKCH polymorphism with the risks of GA and GC.