Presence of simian virus 40 DNA sequences in diffuse large B-cell lymphomas in Tunisia correlates with aberrant promoter hypermethylation of multiple tumor suppressor genes

Potential Pathogenic Impact of Cow’s Milk Consumption and Bovine Milk-Derived Exosomal MicroRNAs in Diffuse Large B-Cell Lymphoma

Epidemiological evidence supports an association between cow’s milk consumption and the risk of diffuse large B-cell lymphoma (DLBCL), the most common non-Hodgkin lymphoma worldwide. This narrative review intends to elucidate the potential impact of milk-related agents, predominantly milk-derived exosomes (MDEs) and their microRNAs (miRs) in lymphomagenesis. Upregulation of PI3K-AKT-mTORC1 signaling is a common feature of DLBCL. Increased expression of B cell lymphoma 6 (BCL6) and suppression of B lymphocyte-induced maturation protein 1 (BLIMP1)/PR domain-containing protein 1 (PRDM1) are crucial pathological deviations in DLBCL. Translational evidence indicates that during the breastfeeding period, human MDE miRs support B cell proliferation via epigenetic upregulation of BCL6 (via miR-148a-3p-mediated suppression of DNA methyltransferase 1 (DNMT1) and miR-155-5p/miR-29b-5p-mediated suppression of activation-induced cytidine deaminase (AICDA) and suppression of BLIMP1 (via MDE let-7-5p/miR-125b-5p-targeting of PRDM1). After weaning with the physiological termination of MDE miR signaling, the infant’s BCL6 expression and B cell proliferation declines, whereas BLIMP1-mediated B cell maturation for adequate own antibody production rises. Because human and bovine MDE miRs share identical nucleotide sequences, the consumption of pasteurized cow’s milk in adults with the continued transfer of bioactive bovine MDE miRs may de-differentiate B cells back to the neonatal “proliferation-dominated” B cell phenotype maintaining an increased BLC6/BLIMP1 ratio. Persistent milk-induced epigenetic dysregulation of BCL6 and BLIMP1 expression may thus represent a novel driving mechanism in B cell lymphomagenesis. Bovine MDEs and their miR cargo have to be considered potential pathogens that should be removed from the human food chain.

Viral Agents as Potential Drivers of Diffuse Large B-Cell Lymphoma Tumorigenesis

Among numerous causative agents recognized as oncogenic drivers, 13% of total cancer cases occur as a result of viral infections. The intricacy and diversity of carcinogenic processes, however, raise significant concerns about the mechanistic function of viruses in cancer. All tumor-associated viruses have been shown to encode viral oncogenes with a potential for cell transformation and the development of malignancies, including diffuse large B-cell lymphoma (DLBCL). Given the difficulties in identifying single mechanistic explanations, it is necessary to combine ideas from systems biology and viral evolution to comprehend the processes driving viral cancer. The potential for more efficient and acceptable therapies lies in targeted medicines that aim at viral proteins or trigger immune responses to either avoid infection or eliminate infected or cancerous cells. In this review, we aim to describe the role of viral infections and their mechanistic approaches in DLBCL tumorigenesis. To the best of our knowledge, this is the first review summarizing the oncogenic potential of numerous viral agents in DLBCL development.

Role of Virus-Induced Host Cell Epigenetic Changes in Cancer

The tumor viruses human T-lymphotropic virus 1 (HTLV-1), hepatitis C virus (HCV), Merkel cell polyomavirus (MCPyV), high-risk human papillomaviruses (HR-HPVs), Epstein-Barr virus (EBV), Kaposi’s sarcoma-associated herpes virus (KSHV) and hepatitis B virus (HBV) account for approximately 15% of all human cancers. Although the oncoproteins of these tumor viruses display no sequence similarity to one another, they use the same mechanisms to convey cancer hallmarks on the infected cell. Perturbed gene expression is one of the underlying mechanisms to induce cancer hallmarks. Epigenetic processes, including DNA methylation, histone modification and chromatin remodeling, microRNA, long noncoding RNA, and circular RNA affect gene expression without introducing changes in the DNA sequence. Increasing evidence demonstrates that oncoviruses cause epigenetic modifications, which play a pivotal role in carcinogenesis. In this review, recent advances in the role of host cell epigenetic changes in virus-induced cancers are summarized.

Investigation of simian virus 40 (SV40) and human JC, BK, MC, KI, and WU polyomaviruses in glioma

The gliomagenesis remains not fully established and their etiological factors still remain obscure. Polyomaviruses were detected and involved in several human tumors. Their potential implication in gliomas has been not yet surveyed in Africa and Arab World. Herein, we investigated the prevalence of six polyomaviruses (SV40, JCPyV, BKPyV, MCPyV, KIPyV, and WUPyV) in 112 gliomas from Tunisian patients. The DNA sequences of polyomaviruses were examined by PCR assays. Viral infection was confirmed by DNA in situ hybridization (ISH) and/or immunohistochemistry (IHC). The relationships between polyomavirus infection and tumor features were evaluated. Specific SV40 Tag, viral regulatory, and VP1 regions were identified in 12 GBM (10.7%). DNA ISH targeting the whole SV40 genome and SV40 Tag IHC confirmed the PCR findings. Five gliomas yielded JCPyV positivity by PCR and DNA ISH (2.7%). However, no BKPyV, KIPyV, and WUPyV DNA sequences were identified in all samples. MCPyV DNA was identified in 30 gliomas (26.8%). For GBM samples, MCPyV was significantly related to patient age (p = 0.037), tumor recurrence (p = 0.024), and SV40 (p = 0.045) infection. No further significant association was identified with the remaining tumor features (p > 0.05) and patient survival (Log Rank, p > 0.05). Our study indicates the presence of SV40, JCPyV, and MCPyV DNA in Tunisian gliomas. Further investigations are required to more elucidate the potential involvement of polyomaviruses in these destructive malignancies.

Association Between Simian Virus 40 and Human Tumors

Simian virus 40 (SV40) is a small DNA tumor virus of monkey origin. This polyomavirus was administered to human populations mainly through contaminated polio vaccines, which were produced in naturally infected SV40 monkey cells. Previous molecular biology and recent immunological assays have indicated that SV40 is spreading in human populations, independently from earlier SV40-contaminated vaccines. SV40 DNA sequences have been detected at a higher prevalence in specific human cancer specimens, such as the brain and bone tumors, malignant pleural mesotheliomas, and lymphoproliferative disorders, compared to the corresponding normal tissues/specimens. However, other investigations, which reported negative data, did not confirm an association between SV40 and human tumors. To circumvent the controversies, which have arisen because of these molecular biology studies, immunological researches with newly developed indirect ELISA tests were carried out in serum samples from patients affected by the same kind of tumors as mentioned above. These innovative indirect ELISAs employ synthetic peptides as mimotopes/specific SV40 antigens. SV40 mimotopes do not cross-react with the homologous human polyomaviruses, BKPyV, and JCPyV. Immunological data obtained from indirect ELISAs, using SV40 mimotopes, employed to analyze serum samples from oncological patients, have indicated that these sera had a higher prevalence of antibodies against SV40 compared to healthy subjects. The main data on (i) the biology and genetics of SV40; (ii) the epidemiology of SV40 in the general population, (iii) the mechanisms of SV40 transformation; (iv) the putative role of SV40 in the onset/progression of specific human tumors, and (v) its association with other human diseases are reported in this review.

Clinical aspects of TP53 gene inactivation in diffuse large B-cell lymphoma

Background

The knowledge about specific mechanisms generating TP53 dysfunction in diffuse large B-cell lymphoma is limited. The aim of the current study was to comprehensively explore TP53 gene variability resulting from somatic mutations, promoter methylation, and allelic imbalance in tumorous tissue of diffuse large B-cell lymphoma (DLBCL).

Methods

DNA samples from 74 patients with DLBCL were used. Genomic DNA was isolated from paraffin blocks of lymph nodes or from extranodal biopsies of tumors by the phenol–chloroform extraction method with guanidine. Analysis of coding sequences of the TP53 gene was based on Sanger’s direct sequencing method. The methylation status of the TP53 promoter was analyzed using by methylation-specific PCR on bisulfite-converted DNA. Assessment of the detected mutations was carried out in the IARC TP53 Database and the TP53 UMD mutation database of human cancer.

Results

The mutations in regions coding for the DNA-binding domain were prevalent (95%). In the analyzed sample of patients, codons 275, 155, 272, and 212 were hotspots of mutations in the TP53 gene. In addition, functionally significant intron mutations (IVS6-36G > C and IVS5 + 43G > T) were detected. Instances of TP53 promoter methylation were observed only in a few samples of diffuse large B-cell lymphoma tissue. Furthermore, loss of heterozygosity was revealed only in the subgroup of patients with altered status of the gene (mutations were detected in five patients and promoter methylation in one case).

Conclusions

Thus, the results suggest that there are two sequential events in the formation of diffuse large B-cell lymphoma in at least some cases. The first event is mutation or methylation of the TP53 promoter, leading to appearance of a cell with increased risk of malignant transformation. The second event is the loss of an intact allele of the gene; this change is necessary for tumorigenesis. We identified TP53 mutation patterns in a Russian cohort of patients with de novo DLBCL who were treated with R-CHOP and R-CHOP-like regimens and confirmed that TP53 mutation status is a valuable prognostic biomarker.

Identification of DNA methylation regulated novel host genes relevant to inhibition of virus replication in porcine PK15 cell using double stranded RNA mimics and DNA methyltransferase inhibitor

During RNA viruses's replication, double-stranded RNA (dsRNA) is normally produced and induce host innate immune response. Most of gene activation due cytokine mediated but which are due to methylation mediated is still unknown. In the study, DNA methylome was integrated with our previous transcriptome data to investigate the differentially methylated regions and genes using MeDIP-chip technology. We found that the transcriptional expressions of 15, 37 and 18 genes were negatively related with their promoter DNA methylation levels in the cells treated by PolyI:C, Aza-CdR, as well as PolyI:C plus Aza-CdR, respectively, compared with the untreated cells. GO analysis revealed hypo-methylated genes (BNIP3L and CDK9) and a hyper-methylated gene (ZC3HAV1) involved in the host response to viral replication. Our results suggest that these novel genes targeted by DNA methylation can be potential markers relevant to virus replication and host innate immune response to set up a medical model of infectious diseases.

DNA Tumor Virus Regulation of Host DNA Methylation and Its Implications for Immune Evasion and Oncogenesis

Viruses have evolved various mechanisms to evade host immunity and ensure efficient viral replication and persistence. Several DNA tumor viruses modulate host DNA methyltransferases for epigenetic dysregulation of immune-related gene expression in host cells. The host immune responses suppressed by virus-induced aberrant DNA methylation are also frequently involved in antitumor immune responses. Here, we describe viral mechanisms and virus–host interactions by which DNA tumor viruses regulate host DNA methylation to evade antiviral immunity, which may contribute to the generation of an immunosuppressive microenvironment during cancer development. Recent trials of immunotherapies have shown promising results to treat multiple cancers; however, a significant number of non-responders necessitate identifying additional targets for cancer immunotherapies. Thus, understanding immune evasion mechanisms of cancer-causing viruses may provide great insights for reversing immune suppression to prevent and treat associated cancers.

The G-BHQ synergistic effect: Improved double quenching molecular beacons based on guanine and Black Hole Quencher for sensitive simultaneous detection of two DNAs

We designed two double quenching molecular beacons (MBs) with simple structure based on guanine (G base) and Black Hole Quencher (BHQ), and developed a new analytical method for sensitive simultaneous detection of two DNAs by synchronous fluorescence analysis. In this analytical method, carboxyl fluorescein (FAM) and tetramethyl-6-carboxyrhodamine (TAMRA) were respectively selected as fluorophore of two MBs, Black Hole Quencher 1 (BHQ-1) and Black Hole Quencher 2 (BHQ-2) were respectively selected as organic quencher, and three continuous nucleotides with G base were connected to organic quencher (BHQ-1 and BHQ-2). In the presence of target DNAs, the two MBs hybridize with the corresponding target DNAs, the fluorophores are separated from organic quenchers and G bases, leading to recovery of fluorescence of FAM and TAMRA. Under a certain conditions, the fluorescence intensities of FAM and TAMRA all exhibited good linear dependence on their concentration of target DNAs (T1 and T2) in the range from 4 × 10^-10 to 4 × 10^-8molL^-1 (M). The detection limit (3σ, n = 13) of T1 was 3 × 10^-10M and that of T2 was 2×10^-10M, respectively. Compared with the existing analysis methods for multiplex DNA with MBs, this proposed method based on double quenching MBs is not only low fluorescence background, short analytical time and low detection cost, but also easy synthesis and good stability of MB probes.

Aberrant promoter methylation of cancer-related genes in human breast cancer

The clinical relevance of aberrant DNA methylation is being increasingly recognized in breast cancer. The present study aimed to evaluate the promoter methylation status of seven candidate genes and to explore their potential use as a biomarker for the diagnosis of breast cancer. A total of 70 Chinese patients with breast cancer were recruited, and matched with 20 patients with benign breast disease (BBD). Methylation-specific polymerase chain reaction was performed to measure the methylation status of selected genes. The protein expression of candidate genes was determined by immunohistochemistry. Hypermethylation of Breast cancer 1, early onset; DNA repair associated (BRCA1), glutathione S-transferase pi 1 (GSTP1), cyclin dependent kinase inhibitor 2A, O-6-methylguanine-DNA methyltransferase, phosphatase and tensin homolog, retinoic acid receptor beta 2 and cyclin D2 was observed to be more common in cancerous tissues (24.3, 31.4, 40.0, 27.1, 48.6, 55.7 and 67.1%, respectively) as compared with BBD controls (0.0, 0.0, 20.0, 25.0, 40.0, 40.0 and 45.0%, respectively). Immunohistochemical analysis demonstrated a correlation between the methylation of the target gene and downregulation of protein expression. When BRCA1 and GSTP1 were combined as the biomarker, the area under the receiver operating characteristic curve reached 0.721 (95% confidence interval, 0.616–0.827). The present findings indicated that promoter methylation of cancer-related genes was frequently observed in patients with breast cancer and was associated with various clinical features. Hypermethylation of BRCA1 and GSTP1 may be used as promising biomarkers for breast cancer.

Specific Antibodies Reacting with SV40 Large T Antigen Mimotopes in Serum Samples of Healthy Subjects

Simian Virus 40, experimentally assayed in vitro in different animal and human cells and in vivo in rodents, was classified as a small DNA tumor virus. In previous studies, many groups identified Simian Virus 40 sequences in healthy individuals and cancer patients using PCR techniques, whereas others failed to detect the viral sequences in human specimens. These conflicting results prompted us to develop a novel indirect ELISA with synthetic peptides, mimicking Simian Virus 40 capsid viral protein antigens, named mimotopes. This immunologic assay allowed us to investigate the presence of serum antibodies against Simian Virus 40 and to verify whether Simian Virus 40 is circulating in humans. In this investigation two mimotopes from Simian Virus 40 large T antigen, the viral replication protein and oncoprotein, were employed to analyze for specific reactions to human sera antibodies. This indirect ELISA with synthetic peptides from Simian Virus 40 large T antigen was used to assay a new collection of serum samples from healthy subjects. This novel assay revealed that serum antibodies against Simian Virus 40 large T antigen mimotopes are detectable, at low titer, in healthy subjects aged from 18–65 years old. The overall prevalence of reactivity with the two Simian Virus 40 large T antigen peptides was 20%. This new ELISA with two mimotopes of the early viral regions is able to detect in a specific manner Simian Virus 40 large T antigen-antibody responses.

DNA methylation patterns in EBV-positive and EBV-negative Hodgkin lymphomas

PURPOSE

Hodgkin lymphoma (HL) is characterized by the presence of Hodgkin and Reed-Sternberg cells. Epstein-Barr virus (EBV) infection is thought to play an important role in the development of HL. Although epigenetic alterations, such as aberrant DNA methylation, are known to contribute to the pathogenesis of various malignancies, little is known about such alterations in HL and their putative relationships with EBV infection.

METHODS

We investigated promoter methylation patterns of seven tumor-associated genes in 53 primary HL cases using methylation-specific PCR (MS-PCR). Concomitantly, the EBV infection status was assessed using PCR, in situ hybridization and immunohistochemistry.

RESULTS

The gene promoter hypermethylation frequencies observed were 77.3 % for P16, 58.5 % for RASSF1A, 50.9 % for CDH1, 45.3 % for DAPK, 43.4 % for GSTP1, 37.7 % for SHP1 and 24.3 % for MGMT. SHP1 gene promoter hypermethylation was more frequently observed in patients at extreme ages (i.e., ≤ 15 and >54 years) than in adult patients (p = 0.006) and in patients with B symptoms (p = 0.03). Interestingly, most of the analyzed gene promoters were more frequently hypermethylated in EBV-negative than in EBV-positive cases, in particular the DAPK gene promoter (58 % versus 27 %, p = 0.04). Furthermore, hypermethylation of multiple gene promoters (≥ 3) was encountered more frequently in females than in males (86 % versus 57 %, p = 0.04), whereas EBV-positive cases were more common among males than females (55 % versus 30 %, p = 0.02).

CONCLUSIONS

Our results indicate that epigenetic changes frequently occur in both EBV-positive and EBV-negative HL. The rates of these changes were found to vary according to clinico-pathological parameters. These observations probably reflect the multitude of factors involved in HL development and the complexity of their interactions with genetic and/or hormonal factors.

Investigation of miR9-1, miR9-2 and miR9-3 Methylation in Hodgkin Lymphoma

BACKGROUND

miR9 is an important tumor suppressor microRNA regulated by DNA methylation in various types of cancers.

METHODS

We analyzed the methylation status of the 3 members of the miR9 family in 58 cases of Hodgkin lymphoma (HL) in comparison to 15 reactive lymph nodes. We also assessed the relationships between miR9 methylation and Epstein-Barr virus (EBV) infection and several clinicopathological parameters.

RESULTS

We found that 84.5% of HL cases had a methylation in at least 1 of the 3 loci of miR9, whereas none of the nontumoral samples was methylated. The highest rate of methylation was found in miR9-2 (5q14.3) in 74.1% of the HL cases, followed by miR9-3 (15q26.1) in 56.9% and miR9-1 (1q22) in only 8.6% (p < 0.001). The promoter methylation of miR9-3 was more frequent in patients older than 15 years than in children (p = 0.02) and among women rather than men (p = 0.02). However, no significant correlation was found between miR9 methylation and EBV infection.

CONCLUSION

These results indicate that miR9 methylation, especially miR9-2, is a frequent event in HL and may be involved in HL pathogenesis, irrespective of EBV infection.

Immunologic evidence of a strong association between non-Hodgkin lymphoma and simian virus 40

BACKGROUND

Non-Hodgkin lymphoma (NHL), the most common cancer of the lymphatic system, is of unknown etiology. The identification of etiologic factors in the onset of NHL is a key event that could facilitate the prevention and cure of this malignancy. Simian virus 40 (SV40) has been considered an oncogenic agent in the onset/progression of NHL.

METHODS

In this study, an indirect enzyme-linked immunosorbent assay with 2 synthetic peptides that mimic SV40 antigens of viral capsid proteins 1 to 3 was employed to detect specific antibodies against SV40. Serum samples were taken from 2 distinct cohorts of NHL-affected patients (NHL1 [n = 89] and NHL2 [n = 61]) along with controls represented by oncologic patients affected by breast cancer (BC; n = 78) and undifferentiated nasopharyngeal carcinoma (UNPC; n = 64) and 3 different cohorts of healthy subjects (HSs; HS1 [n = 130], HS2 [n = 83], and HS3 [n = 87]).

RESULTS

Immunologic data indicated that in serum samples from NHL patients, antibodies against SV40 mimotopes were detectable with a prevalence of 40% in NHL1 patients and with a prevalence of 43% in NHL2 patients. In HSs of the same median age as NHL patients, the prevalence was 16% for the HS1 group (57 years) and 14% for the HS2 group (65 years). The difference was statistically significant (P < .0001 and P < .001). Interestingly, the difference between NHL1/NHL2 patients and BC patients (40%/43% vs 15%, P < .001) and between NHL1/NHL2 patients and UNPC patients (40%/43% vs 25%, P < .05) was significant.

CONCLUSIONS

Our data indicate a strong association between NHL and SV40 and thus a need for innovative therapeutic approaches for this hematologic malignancy.

Methylation of miR124a-1, miR124a-2, and miR124a-3 in Hodgkin lymphoma

Deregulation of the microRNA miR124a by DNA methylation has been implicated in various malignancies, but no study reported its methylation status in Hodgkin lymphoma (HL). We evaluated the methylation of the three loci encoding for miR124a using methylation-specific PCR in 64 HL patients and 15 reactive lymph nodes obtained from patients with nonmalignant diseases. Results were correlated with clinicopathological parameters. Methylation rates of miR124a-1, miR124a-2, and miR124a-3 in HL were 17, 50, and 28%, respectively. None of the nontumoral samples showed aberrant hypermethylation in any of the miR tested. In HL cases, we found that miR124a-1 methylation correlates with high-risk International Prognostic Score (IPS) (score >3, p = 0.04) and that miR124a-2 methylation was more frequent in children (82.3%, p = 0.006) and men (63.9%, p = 0.01). Methylation of miR124a-3 was associated with advanced Ann-Arbor stages (p = 0.007). The survival analysis showed that methylation of at least one of the miR124a genes was associated with shortened event-free survival in univariate (p = 0.03) and multivariate (p = 0.02) analyses. These results suggest that miR124a methylation is associated with aggressive HL disease and may be an interesting factor for predicting treatment response.

Neutralizing and IgG antibodies against simian virus 40 in healthy pregnant women in Italy

OBJECTIVE

Polyomavirus simian virus 40 (SV40) sequences have been detected in various human specimens and SV40 antibodies have been found in human sera from both healthy individuals and cancer patients. This study analyzed serum samples from healthy pregnant women as well as cord blood samples to determine the prevalence of SV40 antibodies in pregnancy.

METHODS

Serum samples were collected at the time of delivery from two groups of pregnant women as well as cord bloods from one group. The women were born between 1967 and 1993. Samples were assayed by two different serological methods, one group by neutralization of viral infectivity and the other by indirect ELISA employing specific SV40 mimotopes as antigens. Viral DNA assays by real-time polymerase chain reaction were carried out on blood samples.

RESULTS

Neutralization and ELISA tests indicated that the pregnant women were SV40 antibody-positive with overall prevalences of 10.6% (13/123) and 12.7% (14/110), respectively. SV40 neutralizing antibodies were detected in a low number of cord blood samples. Antibody titers were generally low. No viral DNA was detected in either maternal or cord bloods.

CONCLUSIONS

SV40-specific serum antibodies were detected in pregnant women at the time of delivery and in cord bloods. There was no evidence of transplacental transmission of SV40. These data indicate that SV40 is circulating at a low prevalence in the northern Italian population long after the use of contaminated vaccines.

RB1 gene in Merkel cell carcinoma: hypermethylation in all tumors and concurrent heterozygous deletions in the polyomavirus-negative subgroup

Sequestration of the tumor suppressor retinoblastoma protein (RB) by the Merkel cell polyomavirus (MCV) is a crucial step in the pathogenesis of Merkel cell carcinoma (MCC). RB expression is frequently lost, particularly in MCV-negative MCC tumors, through yet unknown mechanisms. We compared the genomic copy number changes of 13 MCV-positive and 13 -negative MCC tumors by array comparative genomic hybridization. The analysis revealed increased genomic instability, amplification of 1p34.3-1p34.2, and losses of 11p in the absence of MCV infection. Deletions of the RB1 locus were also detected at high rates in MCV-negative tumors. None of the tumors with heterozygous RB1 losses expressed RB in immunohistochemistry. RB1 promoter hypermethylation was studied with a methylation-specific multiplex ligation-dependent probe amplification technique. The RB1 promoter was methylated in all tumor specimens at CpG islands located close to the ATG start codon, albeit at low levels. The pattern of hypermethylation was similar in all MCC samples, despite RB expression, survival or MCV status. In conclusion, the frequent heterozygous losses of the RB1 locus could partly explain the decreased RB expression in MCV-negative MCC tumors, although the effects of RB1 mutations, coinciding promoter hypermethylation and, for example, miRNA regulation, cannot be excluded.

Antibodies reacting with Simian virus 40 mimotopes in serum samples from patients with thalassaemia major

BACKGROUND

Simian virus 40 (SV40) is a small DNA tumour virus. Footprints of the virus have been detected in different humam lymphoproliferative disorders and in blood specimens of blood from healthy blood donors. This study was carried out to verify whether SV40 antibodies can be detected in serum samples from multiply transfused patients with thalassaemia major.

MATERIALS AND METHODS

An indirect enzyme-linked immunosorbent assay was employed, using SV40 specific synthetic peptides mimicking the antigens of the viral capsid proteins 1-2-3, to test for the presence of antibodies to SV40 in serum samples taken from patients affected by transfusion-dependent thalassaemia major (n=190) and healthy blood donors (n=251).

RESULTS

The prevalence of antibodies against SV40 was higher in patients than in controls (24% vs 17%). The prevalence increased and was significantly higher in the older age group of patients affected by thalassemia major than in controls (38% vs 20%, p<0.04).

DISCUSSION

The higher prevalence of serum antibodies against simian virus 40 in older, multiply transfused patients with thalassamia major than in controls suggests that this virus, or a closely related yet unknown human polyomavirus, could have been transmitted in the past by transfusion with whole blood. At the same time, our data indicate no significant differences in prevalence of SV40 antibodies in patients and controls of younger age thus suggesting that current transfusion methods with leucodepletion and filtered red cells are safe.

DNMT3B7 expression related to MENT expression and its promoter methylation in human lymphomas

DNA methyltransferase (DNMT) 3B7 is the most expressed DNMT3B splice variant. It was reported that the loss of DNMT3B function led to overexpression of the MEthylated in Normal Thymocyes (MENT) and accelerated mouse lymphomagenesis. We investigated the DNMT3B7 expression and its relationship to MENT expression and promoter methylation in human lymphomas. DNMT3B7 and MENT expression were significantly (p<0.0001, p<0.01) higher in lymphomas than in non-malignant. Expression of DNMT3B7 and MENT were associated with MENT promoter hypomethylation. DNMT3B7 overexpression might interfere with the normal DNA methylation mechanism required for silencing the MENT proto-oncogene, and may accelerate human lymphomagenesis.

Detection of human JCPyV and BKPyV in diffuse large B-cell lymphoma of the GI tract

Previous studies have demonstrated that infection with human polyomavirus, such as JCPyV and BKPyV, might be associated with various human tumors. However, an association between human JCPyV and BKPyV infection and diffuse large B-cell lymphoma (DLBCL) has not been reported. The purpose of this study was to examine DLBCLs of the gastrointestinal tract for evidence of human polyomavirus infection. Nested PCR and DNA sequencing were employed for viral DNA detection and viral genotype identification. In addition, two viral proteins, the large tumor antigen (LT) and the major structural protein (VP1), were detected by immunohistochemistry (IHC). Human JCPyV and BKPyV DNA was detected in 14 out of 16 tissue samples (87.5%), whereby nine cases were infected with JCPyV and five cases were infected with BKPyV. Both archetypal and rearranged genotypes of JCPyV and BKPyV were detected in the tissues. LT was detected in 11 tissue samples (68.75%). However, VP1 was not detected in any of the tissue samples. The presence of human JCPyV and BKPyV DNA and protein in DLBCL tissues of gastrointestinal tract were first reported in this study. The current results provide evidence of a possible association between human JCPyV and BKPyV infection and DLBCL.

Detection of human JCPyV and BKPyV in diffuse large B-cell lymphoma of the GI tract

Previous studies have demonstrated that infection with human polyomavirus, such as JCPyV and BKPyV, might be associated with various human tumors. However, an association between human JCPyV and BKPyV infection and diffuse large B-cell lymphoma (DLBCL) has not been reported. The purpose of this study was to examine DLBCLs of the gastrointestinal tract for evidence of human polyomavirus infection. Nested PCR and DNA sequencing were employed for viral DNA detection and viral genotype identification. In addition, two viral proteins, the large tumor antigen (LT) and the major structural protein (VP1), were detected by immunohistochemistry (IHC). Human JCPyV and BKPyV DNA was detected in 14 out of 16 tissue samples (87.5%), whereby nine cases were infected with JCPyV and five cases were infected with BKPyV. Both archetypal and rearranged genotypes of JCPyV and BKPyV were detected in the tissues. LT was detected in 11 tissue samples (68.75%). However, VP1 was not detected in any of the tissue samples. The presence of human JCPyV and BKPyV DNA and protein in DLBCL tissues of gastrointestinal tract were first reported in this study. The current results provide evidence of a possible association between human JCPyV and BKPyV infection and DLBCL.

Genome-wide effects of DNA methyltransferase inhibitor on gene expression in double-stranded RNA transfected porcine PK15 cells

Double-stranded RNA (dsRNA) is produced in host cells during viral replication. The effects of DNA demethylation on gene expression in dsRNA transfected swine cells are unclear. The study aims to profile the transcriptome changes which are induced by DNA methyltransferase inhibitor (Aza-CdR) in porcine PK15 cells transfected with viral-like dsRNA (Poly(I:C)). A total of 44, 76 and 952 differentially expressed genes (DEGs) were detected in the cells treated by Poly(I:C) plus Aza-CdR (P+A), Poly(I:C) (P) or Aza-CdR (A) alone compared to the controls (C). Immune response-related pathways are observed in the comparison of A vs. C and P vs. C, and the genes in the pathways were recovered in the comparison of (P+A) vs. C. GO analysis indicated that Aza-CdR has negative regulatory effects on viral reproduction. The results suggest that the stimulant of Poly(I:C) could be regressed by Aza-CdR. These observations provide new insights into the epigenetic regulatory effects on viral replication.

Genetic methylation and lymphoid malignancies: biomarkers of tumor progression and targeted therapy

Lymphoid malignancies, mainly including lymphocytic leukemia and lymphoma, are a group of heterogeneous diseases. Although the clinical outcome of patients has been significantly improved with current immuno-chemotherapy, definitive biomarkers remain to be investigated, particularly those reflecting the malignant behavior of tumor cells and those helpful for developing optimal targeted therapy. Recently, genome-wide analysis reveals that altered genetic methylations play an important role in tumor progression through regulation of multiple cellular transduction pathways. This review describes the pathogenetic effect of the aberrant genetic methylation in lymphoid malignancies, with special emphasis on potential therapeutic strategies targeting key signaling networks.

Extended lifespan of normal human B lymphocytes experimentally infected by SV40 or transfected by SV40 large T antigen expression vector

SV40 footprints were detected in different lymphoproliferative disorders and in blood specimens of healthy donors. However, little is known on the ability of SV40 to infect/transform normal human B-lymphocytes. In this in vitro study, experimental SV40 infection and SV40 Tag transfection of normal human B-lymphocytes from healthy blood donors were carried out. In SV40 infected/transfected purified B-cells, during the time course analyses, viral DNA sequences were detected by PCR, while Tag mRNA and protein were revealed by RT-PCR and immunocytochemistry, respectively. Trypan blue and Alamar blue assays showed an increase in number of cells and cell viability of infected/transfected B-cells up to day 50, then a drastic and constant cell number reduction was observed in cultures. Approximately 50% of both infected and transfected B-cells appeared morphologically transformed. SV40 viral progeny and its titer from infected B-cells was determined by plaque assay in permissive CV-1 cells. Our data indicate that human B-cells can be efficiently infected by SV40, release a viral progeny, while at the same time are transformed. SV40 infected/Tag transfected B-cells may represent an experimental model of study for investigating new biomarkers and targets for innovative therapeutic approaches in human B-cell malignancies.

Dysfunction of the TP53 tumor suppressor gene in lymphoid malignancies

Mutations of the TP53 gene and dysregulation of the TP53 pathway are important in the pathogenesis of many human cancers, including lymphomas. Tumor suppression by p53 occurs via both transcription-dependent activities in the nucleus by which p53 regulates transcription of genes involved in cell cycle, DNA repair, apoptosis, signaling, transcription, and metabolism; and transcription-independent activities that induces apoptosis and autophagy in the cytoplasm. In lymphoid malignancies, the frequency of TP53 deletions and mutations is lower than in other types of cancer. Nonetheless, the status of TP53 is an independent prognostic factor in most lymphoma types. Dysfunction of TP53 with wild-type coding sequence can result from deregulated gene expression, stability, and activity of p53. To overcome TP53 pathway inactivation, therapeutic delivery of wild-type p53, activation of mutant p53, inhibition of MDM2-mediated degradation of p53, and activation of p53-dependent and -independent apoptotic pathways have been explored experimentally and in clinical trials. We review the mechanisms of TP53 dysfunction, recent advances implicated in lymphomagenesis, and therapeutic approaches to overcoming p53 inactivation.

Patterns of aberrant DNA hypermethylation in nasopharyngeal carcinoma in Tunisian patients

BACKGROUND

Aberrant methylation in the promoter of tumor-related genes is associated closely with epigenetically mediated gene silencing. The aim of the present study was to evaluate the methylation profile of Tunisian nasopharyngeal carcinoma (NPC) and to determine the clinicopathological features of tumors showing this epigenetic alteration.

METHODS

Thirty-six archival NPC biopsies were investigated in comparison with 19 non-tumor nasopharyngeal tissue specimens. DNA methylation status of ten tumor-suppressor and related genes was analyzed by using methylation-specific PCR. The Epstein-Barr virus (EBV) presence was verified by PCR and in situ hybridization and the LMP1 oncoprotein expression was analyzed by immunohistochemistry. Findings were then correlated with clinicopathological variables (Patients' gender and age, tumor histological subtype and stage).

RESULTS

Hypermethylation frequencies of the investigated genes in NPC biopsies were 75% for RASSFIA, 58.3% for SHP1, 47.2% for DAPK, 33.3% for P16, 31% for RARβ2, 19.4% for GSTP1 and TIMP3, 11% for APC and CDH1, and 5.5% for MGMT. In non-tumor nasopharyngeal samples, hypermethylation was detected in lower frequencies in 6 genes (SHP 26.3%, P16 21%, RARβ2 21%, DAPK 15.8%, TIMP3 10.5%, and GSTP 5.3%). Hypermethylation of RARβ2 promoter was more frequent in tumors with lymph node metastasis than those without metastasis (43.5% vs 0%, p=0.03). Methylation of RASSF1A was more frequently detected in non-keratinizing NPC than in undifferentiated subtype (100% vs 66.7%; p=0.05). A trend toward positive association was found between an increased number of methylated genes and LMP1 expression (p=0.07). However, no significant association was found for the remaining variables.

CONCLUSIONS

This study indicates that hypermethylation of multiple genes is a common alteration in nasopharyngeal carcinomas in Tunisian patients and that this epigenetic change may play a role in the nasopharyngeal carcinogenesis.

Simian virus 40 transformation, malignant mesothelioma and brain tumors

Simian virus 40 (SV40) is a DNA virus isolated in 1960 from contaminated polio vaccines, that induces mesotheliomas, lymphomas, brain and bone tumors, and sarcomas, including osteosarcomas, in hamsters. These same tumor types have been found to contain SV40 DNA and proteins in humans. Mesotheliomas and brain tumors are the two tumor types that have been most consistently associated with SV40, and the range of positivity has varied about from 6 to 60%, although a few reported 100% of positivity and a few reported 0%. It appears unlikely that SV40 infection alone is sufficient to cause human malignancy, as we did not observe an epidemic of cancers following the administration of SV40-contaminated vaccines. However, it seems possible that SV40 may act as a cofactor in the pathogenesis of some tumors. In vitro and animal experiments showing cocarcinogenicity between SV40 and asbestos support this hypothesis.

Down-regulation of promoter methylation level of CD4 gene after MDV infection in MD-susceptible chicken line

Background

Marek’s disease virus (MDV) is an oncovirus that induces lymphoid tumors in susceptible chickens, and may affect the epigenetic stability of the CD4 gene. The purpose of this study was to find the effect of MDV infection on DNA methylation status of the CD4 gene differed between MD-resistant (L6₃) and –susceptible (L7₂) chicken lines.

Methods

Chickens from each line were divided into two groups with one group infected by MDV and the other group as uninfected controls. Then, promoter DNA methylation levels of the CD4 gene were measured by Pyrosequencing; and gene expression analysis was performed by quantitative PCR.

Results

Promoter methylation of the CD4 gene was found to be down-regulated in L7₂ chickens only after MDV infection. The methylation down-regulation of the CD4 promoter is negatively correlated with up-regulation of CD4 gene expression in the L7₂ spleen at 21 dpi.

Conclusions

The methylation fluctuation and mRNA expression change of CD4 gene induced by MDV infection suggested a unique epigenetic mechanism existed in MD-susceptible chickens.

Fibroblast-derived HB-EGF promotes Cdx2 expression in esophageal squamous cells

The molecular basis of attaining columnar phenotype in Barrett's esophagus is poorly understood. One hypothesis states that factors locally produced by cells of mesenchymal origin in chronic reflux esophagitis induce metaplastic transformation. This study was performed to elucidate the factors secreted from fibroblasts that cause columnar phenotype in adjacent squamous epithelium. Human fibroblast cells were exposed to acidified medium for 20 min, followed by medium neutralization for 2 h, and then total RNA was hybridized to Sentrix Human-6 Expression BeadChips. Furthermore, esophageal mucosal biopsy specimens from reflux esophagitis patients were examined for HB-EGF expression using immunohistochemistry. In addition, cells from the human esophageal squamous epithelial cell line HET1A were treated with recombinant HB-EGF, and changes in expressions of Cdx2 and columnar markers were analyzed. The gene expression profile revealed significant upregulation of a variety of growth factors and inflammatory chemokines in response to acid exposure. Among them, HB-EGF was upregulated more than 10-fold. Biopsy specimens from reflux esophagitis patients showed a strong expression of HB-EGF in fibroblast cells underlying the damaged epithelium. Furthermore, in vitro stimulation of HET1A cells with HB-EGF increased Cdx2 in dose-dependent manners. Functional analysis of human Cdx2 promoter also revealed its upregulation by HB-EGF stimulation, showing the role of potential responsive elements (AP-1 and NF-kappaB) for its transcriptional activation. Moreover, the columnar markers cytokeratin 7 and villin were also upregulated by HB-EGF stimulation. HB-EGF induces several genes characteristics of columnar phenotypes of esophageal squamous epithelium in a paracrine manner.

DNA methyltransferase DNMT3b protein overexpression as a prognostic factor in patients with diffuse large B-cell lymphomas

Diffuse large B-cell lymphomas (DLBCL) are the most common type of aggressive lymphomas, with considerable heterogeneity in clinical presentation, molecular characteristics, and outcome. Previous studies have showed significant correlations between DNA methyltransferase (DNMT) overexpression and unfavorable prognosis in human cancers. Therefore, we investigated in this study the biological and prognostic significance of DNMT1, DNMT3a, and DNMT3b protein expression in DLBCL. DNA methyltransferase (DNMT) expression was analyzed by immunohistochemistry in 81 DLBCL cases and correlated with clinicopathological parameters. Kaplan-Meier curves were used to estimate survival rates, and the Cox proportional hazard regression model was used to evaluate the prognostic impact of DNMT expression. Our results showed that overexpression of DNMT1, DNMT3a, and DNMT3b were detected in 48%, 13%, and 45% of investigated cases, respectively. DNA methyltransferase 1 (DNMT1) and DNMT3b overexpression was significantly correlated with advanced clinical stages (P = 0.028 and P = 0.016, respectively). Moreover, concomitant expression of DNMT1 and DNMT3b was significantly correlated with resistance to treatment (P = 0.015). With regard to survival rates, although data was available only for 40 patients, DNMT3b overexpression was significantly correlated with shorter overall survival (P = 0.006) and progression-free survival (P = 0.016). Interestingly, multivariate analysis demonstrated that DNMT3b overexpression was an independent prognostic factor for predicting shortened overall survival (P = 0.004) and progression-free survival (P = 0.024). In conclusion, DNMT3b overexpression was identified as an independent prognostic factor for predicting shortened survival of patients with DLBCL and could be, therefore, useful in identifying patients who would benefit from aggressive therapy.

The presence of JC virus in gastric carcinomas correlates with patient's age, intestinal histological type and aberrant methylation of tumor suppressor genes

JC virus (JCV) is a neurotropic polyomavirus and the causative agent of progressive multifocal leukoencephalopathy. A role for JCV in gastrointestinal malignancies has been recently suggested. This study was carried out to determine the prevalence of polyomaviruses including JCV, BKV and SV40 in gastric cancers in Tunisia and to determine the clinicopathological characteristics of virus-associated gastric carcinomas. The presence of polyomaviruses DNA sequences was surveyed in 61 cases of primary gastric carcinomas and in 53 paired non-tumor gastric mucosa by PCR. Findings were correlated to clinicopathological parameters, p53 expression and methylation status of 11 tumor-related genes. Using PCR assays, JCV T-antigen sequence was more frequently detected in gastric carcinomas than in non-tumor gastric mucosa (26 vs 6%, P=0.03), while those of SV40 and BKV were not detected in any cases. Correlation analysis showed that JCV had higher frequency in patients older than 55 years (P=0.034) and in the intestinal histological type (P=0.04). With regard to methylation status, P16 and P14 showed significantly higher methylation frequencies in JCV-positive gastric carcinomas than in JCV-negative cases (P=0.007 and P=0.003, respectively). Moreover, the mean of the methylation index was significantly higher in JCV-positive than in JCV-negative cases (P=0.024). In multivariate logistic regression analysis, age of patients and the methylation index are only the two independent factors associated with JCV infection. Kaplan-Meier survival analysis showed a trend toward better survival for JCV-associated gastric carcinomas patients (log-rank, P=0.11). Our study suggests a role of JCV as cofactor in the pathogenesis of the intestinal type of gastric carcinomas in older persons.

Variable frequency of polyomavirus SV40 and herpesvirus EBV in lymphomas from two different urban population groups in Houston, TX

BACKGROUND

Studies have reported differing frequencies of detection of polyomavirus simian virus 40 (SV40) in association with human lymphomas.

OBJECTIVE

We addressed the hypothesis that SV40 positivity in lymphomas can vary among sampled populations.

STUDY DESIGN

Archival paraffin-embedded lymphoma specimens (n=171) from patients at two urban hospitals in Houston, TX, USA, were analyzed following a cross-sectional study design. Extracted DNAs were characterized by quantitative polymerase chain reaction for the cellular RNase P gene and for SV40 and herpesvirus Epstein-Barr virus (EBV) sequences.

RESULTS

Patient characteristics of the two study populations differed significantly whereas the classification of tumor types studied did not. SV40 DNA was detected more frequently in lymphomas from the public hospital population (10/44, 23%) than in lymphomas from the veterans' hospital (VAMC) (4/127, 3%; P<0.0001). EBV detection in lymphomas also differed between the two groups (17/44, 39% vs. 23/127, 18%; P=0.01). SV40 positivity was associated with a younger age category of VAMC lymphoma patients (P=0.02). Expression of T-antigen was detected by immunohistochemistry in half of lymphomas that contained SV40 DNA. Variation was observed in the quality and quantity of DNA recovered from paraffin-embedded specimens, but there was no difference in recoveries of DNA from samples from the two hospitals.

CONCLUSIONS

This study demonstrated that, in a direct comparison, the prevalence of SV40 DNA in lymphomas can differ significantly between groups with different demographic distributions.

Macrophages of multiple sclerosis patients display deficient SHP-1 expression and enhanced inflammatory phenotype

Recent studies in mice have demonstrated that the protein tyrosine phosphatase SHP-1 is a crucial negative regulator of proinflammatory cytokine signaling, TLR signaling, and inflammatory gene expression. Furthermore, mice genetically lacking SHP-1 (me/me) display a profound susceptibility to inflammatory CNS demyelination relative to wild-type mice. In particular, SHP-1 deficiency may act predominantly in inflammatory macrophages to increase CNS demyelination as SHP-1-deficient macrophages display coexpression of inflammatory effector molecules and increased demyelinating activity in me/me mice. Recently, we reported that PBMCs of multiple sclerosis (MS) patients have a deficiency in SHP-1 expression relative to normal control subjects indicating that SHP-1 deficiency may play a similar role in MS as to that seen in mice. Therefore, it became essential to examine the specific expression and function of SHP-1 in macrophages from MS patients. Herein, we document that macrophages of MS patients have deficient SHP-1 protein and mRNA expression relative to those of normal control subjects. To examine functional consequences of the lower SHP-1, the activation of STAT6, STAT1, and NF-kappaB was quantified and macrophages of MS patients showed increased activation of these transcription factors. In accordance with this observation, several STAT6-, STAT1-, and NF-kappaB-responsive genes that mediate inflammatory demyelination were increased in macrophages of MS patients following cytokine and TLR agonist stimulation. Supporting a direct role of SHP-1 deficiency in altered macrophage function, experimental depletion of SHP-1 in normal subject macrophages resulted in an increased STAT/NF-kappaB activation and increased inflammatory gene expression to levels seen in macrophages of MS patients. In conclusion, macrophages of MS patients display a deficiency of SHP-1 expression, heightened activation of STAT6, STAT1, and NF-kappaB and a corresponding inflammatory profile that may be important in controlling macrophage-mediated demyelination in MS.

Biological significance of promoter hypermethylation of tumor-related genes in patients with gastric carcinoma

BACKGROUND

DNA promoter hypermethylation is a potential means of inactivating tumor-related genes in several types of cancers.

METHODS

We investigated aberrant promoter hypermethylation of eleven tumor-related genes in 68 gastric carcinomas and 53 adjacent non-tumor tissues using methylation-specific PCR, and we correlated the findings with clinico-pathological features.

RESULTS

In gastric carcinoma tissues, hypermethylation frequencies of the investigated genes were 61.8% for RASSFIA, 52.9% for APC, 36.8% for MGMT, 30.9% for DAPK, 29.4% for P16, 26.5% for P14, 25% for SHP1, 23.5% for RAR-beta2, 20.6% for GSTP1, 13.2% for TIMP3, and 8.8% for hMLH1. For adjacent non-tumor samples, the frequencies of methylation were respectively 5.7, 37.7, 5.7, 24.5, 3.8, 5.7, 20.8, 5.7, 1.9, 3.8, and 0%. Hypermethylation of P16 correlates with intestinal subtype and cardiac location (P = 0.044 and P = 0.004, respectively), whereas methylation of GSTP1 correlates with diffuse subtype (P = 0.050). Methylation of SHP1 was associated with EBV infection (P = 0.014). Methylation of APC and RAR-beta2 genes were significantly associated with improved patient's outcome (P = 0.007 and P = 0.042, respectively).

CONCLUSIONS

Our data suggest that methylation of multiple genes may be involved in the pathogenesis and correlated with the prognosis of gastric carcinomas.

Microbe-induced epigenetic alterations in host cells: the coming era of patho-epigenetics of microbial infections. A review

It is well documented that the double-stranded DNA (dsDNA) genomes of certain viruses and the proviral genomes of retroviruses are regularly targeted by epigenetic regulatory mechanisms (DNA methylation, histone modifications, binding of regulatory proteins) in infected cells. In parallel, proteins encoded by viral genomes may affect the activity of a set of cellular promoters by interacting with the very same epigenetic regulatory machinery. This may result in epigenetic dysregulation and subsequent cellular dysfunctions that may manifest in or contribute to the development of pathological changes (e.g. initiation and progression of malignant neoplasms; immunodeficiency). Bacteria infecting mammals may cause diseases in a similar manner, by causing hypermethylation of key cellular promoters at CpG dinucleotides (promoter silencing, e.g. by Campylobacter rectus in the placenta or by Helicobacter pylori in gastric mucosa). I suggest that in addition to viruses and bacteria, other microparasites (protozoa) as well as macroparasites (helminths, arthropods, fungi) may induce pathological changes by epigenetic reprogramming of host cells they are interacting with. Elucidation of the epigenetic consequences of microbe-host interactions (the emerging new field of patho-epigenetics) may have important therapeutic implications because epigenetic processes can be reverted and elimination of microbes inducing patho-epigenetic changes may prevent disease development.

Evidence for a role of the Simian Virus 40 in human breast carcinomas

AIMS OF THE STUDY

The aim of this study was to investigate whether the Simian Virus 40 (SV40) is implicated in human breast carcinomas (BC).

EXPERIMENTAL DESIGN

SV40 presence was investigated by PCR assays targeting the Tag, the regulatory, and the VP1 regions in 109 invasive breast ductal carcinomas from Tunisian women. We also examined the relationship between the presence of SV40 and promoter methylation status of 15 tumor-related genes. Immunohistochemistry was used to investigate the expression of Tag, estrogen and progesterone receptors, HER2, and P53.

RESULTS

SV40 DNA sequences were detected in 22% of tumors and in only 1.8% of the matched non-tumoral tissues. Using immunohistochemistry, SV40 was detected in the tumor cells. Hypermethylation frequencies were 78% for RASSF1A, 66% for SHP1, 61% for HIN1 and BRCA1, 47% for P16 and ER, 42% for CDH1 and APC, 40% for BLU, 35% for DAPK, 34% for RARbeta2, 27% for GSTP1, 17% for TIMP3, 14% for CCND2, and 8% for hMLH1. Interestingly, the frequencies of RASSF1A, SHP1, BRCA1, and TIMP3 methylation, and the mean of the methylation index (MI) were significantly higher in SV40-positive than in SV40-negative cases (P-values ranging from 0.043 to 0.003). Moreover, SV40 presence correlates with P53 protein accumulation (32.7% vs. 13.3%; P=0.015) and HER2 low expression (3.7% vs. 28%; P=0.008). We also found SV40 more frequently in patients over 50 years than in younger patients (34.8% vs. 12.3%; P=0.006).

CONCLUSIONS

This study is the first to demonstrate the presence of SV40 in human BC and provides data supporting a role for this virus in the pathogenesis of these tumors.

SV40 lymphomagenesis in Syrian golden hamsters

Simian virus 40 (SV40) isolates differ in oncogenic potential in Syrian golden hamsters following intraperitoneal inoculation. Here we describe the effect of intravenous exposure on tumor induction by SV40. Strains SVCPC (simple regulatory region) and VA45-54(2E) (complex regulatory region) were highly oncogenic following intravenous inoculation, producing a spectrum of tumor types. Three lymphoma cell lines were established; all expressed SV40 T-antigen, were immortalized for growth in culture, and were tumorigenic following transplantation in vivo. New monoclonal antibodies directed against hamster lymphocyte surface antigens are described. The cell lines expressed MHC class II and macrophage markers and were highly phagocytic, indicating a histiocytic origin. Many hamsters that remained tumor-free developed SV40 T-antigen antibodies, suggesting that viral replication occurred. This study shows that route of exposure influences the pathogenesis of SV40-mediated carcinogenesis, that SV40 strain VA45-54(2E) is lymphomagenic in hamsters, that hamster lymphoid cells of histiocytic origin can be transformed in vivo and established in culture, and that reagents to hamster leukocyte differentiation molecules are now available.

Detection of polyomavirus SV40 in tonsils from immunocompetent children

BACKGROUND

BK virus (BKV), JC virus (JCV) and simian virus 40 (SV40) are nonenveloped DNA viruses, members of the family Polyomaviridae. BK and JC viruses establish persistent infections in humans, and evidence suggests that SV40 can infect humans, as well. Whether persistence occurs in the lymphoid system is unknown.

METHODS

Paraffin-embedded tonsils from 220 immunocompetent children (mean age 9.3 years) were examined by polymerase chain reaction (PCR) to detect viral DNA of BKV, JCV, SV40, and Epstein-Barr virus (EBV).

RESULTS

Polyomavirus-specific DNA sequences were detected in 8.3% (29/351) of specimens collected from 220 children. Twenty-one (9.5%) children had polyomavirus DNA present in at least one tonsil, with sequences identified as SV40 (n=20) and BKV (n=1). Polyomavirus JCV was not detected. Among patients positive for SV40, 8 of 14 (57%) contained viral DNA in both available tonsils. EBV DNA was detected in 99 (28.2%) samples from 67 (30.5%) patients. Eleven samples (3.1%) from 8 (3.6%) children were positive for both polyomavirus and EBV. SV40-positive children were significantly older than the SV40-negative subjects (P<0.001). T-antigen expression was detected in an SV40 DNA-positive tonsil by immunohistochemistry.

CONCLUSIONS

These results suggest that SV40 can infect tonsils, that lymphoid tissue may represent a site for polyomavirus persistence, and that immunohistochemistry is not a useful detection assay when there are very few virus-infected cells in a tissue.

Prognostic significance of aberrant promoter hypermethylation of CpG islands in patients with diffuse large B-cell lymphomas

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) exhibits heterogeneous clinical features and a marked variable response to treatment.

PATIENTS AND METHODS

We investigated the prognostic significance of the methylation status of DAPK, GSTP1, P14, P15, P16, P33, RB1, SHP1, CDH1, APC, BLU, VHL, TIMP3, and RASSF1A genes in 46 DLBCL specimens from Tunisian patients. Methylation status of each gene was correlated with clinicopathological parameters including the International Prognostic Index (IPI), the germinal center immunophenotype, and response to treatment and survival. Overall survival (OS) and disease-free survival (DFS) rates were calculated by the Kaplan-Meier method and differences were compared with the log-rank test.

RESULTS

Hypermethylation of SHP1 was associated with elevated lactate dehydrogenase level (P = 0.031). P16 and VHL were frequently hypermethylated in patients with high IPI scores (P = 0.006 and 0.004) and a performance status of two or more (P = 0.007 and 0.047). In addition, hypermethylation of P16 was significantly associated with advanced clinical stages and B symptoms (P = 0.041 and 0.012). Interestingly, hypermethylation of DAPK was significantly correlated with resistance to treatment (P = 0.023). With regard to survival rates, promoter hypermethylation of DAPK, P16, and VHL were significantly associated with shortened OS (P = 0.003, 0.001, and 0.017, respectively) and DFS (P = 0.006, 0.003, and 0.046, respectively). In multivariate analysis, hypermethylation of DAPK remains an independent prognostic factor in predicting shortened OS (P = 0.001) and DFS (P = 0.024), as well as the IPI and the germinal center status.

CONCLUSIONS

This study demonstrates that DLBCLs with hypermethylated P16, VHL, DAPK, and SHP1 commonly show a biologically aggressive phenotype and worse prognosis. Interestingly, hypermethylation of DAPK was found to be an independent prognostic factor that may be used in conjunction with the conventional prognostic factors such as the IPI and the germinal center status.

Presence of simian virus 40 in diffuse large B-cell lymphomas in Tunisia correlates with germinal center B-cell immunophenotype, t(14;18) translocation, and P53 accumulation

Previously we have reported the presence of simian virus 40 DNA in 56% of diffuse large B-cell lymphomas in Tunisia. Here, we investigated the relationship between the status of simian virus 40 and t(14;18) translocation, germinal center status, and P53 and BCL2 expression to assess the clinical and biological relevance of simian virus 40 presence in diffuse large B-cell lymphomas. Therefore, we evaluated by immunohistochemistry the expression patterns of CD10, BCL6, MUM1, BCL2, and P53 in 86 diffuse large B-cell lymphomas (48 simian virus 40-positive and 38 simian virus 40-negative cases). The t(14;18) translocation was investigated by polymerase chain reaction. Immunostaining patterns for CD10, BCL6, and MUM1 were used to subclassify diffuse large B-cell lymphoma cases as germinal center or non-germinal center phenotypes. Germinal center phenotype, t(14;18), P53, and BCL2 expression were found in 71, 30, 55, and 65% of cases, respectively. Interestingly, germinal center phenotype, t(14;18), and P53 accumulation were found to be more frequent in simian virus 40-positive cases than in simian virus 40-negative ones (81, 44, 69 vs 58, 13, 37%; P=0.018, 0.002, and 0.003, respectively). However, there were no correlations between the presence of simian virus 40 and the expression of CD10, BCL6, MUM1 and BCL2, patient's age and gender, clinical stage, or the International Prognosis Index. Multivariate logistic regression analyses revealed that the germinal center phenotype, P53 accumulation, and t(14;18) were independent factors for simian virus 40 association (P=0.029, 0.006, and 0.014, respectively). There were no significant differences in overall survival regarding P53, BCL2, or t(14;18) status. However, patients with germinal center phenotype or low International Prognosis Index scores displayed a significantly better survival than those with non-germinal center phenotype or high International Prognosis Index scores (P=0.003 and 0.0001, respectively). These two prognosis factors remain independent in multivariate analyses (P=0.001 and <0.0001, respectively). Interestingly, among patients with germinal center phenotype, simian virus 40-positive subgroup displayed a significantly shorter survival than simian virus 40-negative subgroup (P=0.034). In summary, these findings support a role of simian virus 40 in the pathogenesis of diffuse large B-cell lymphomas. On other hand, they suggest that a significant proportion of diffuse large B-cell lymphoma cases with germinal center phenotype may result from early transformation by simian virus 40, mainly those harboring the t(14;18). Modern Pathology (2008) 21, 282-296; doi:10.1038/modpathol.3800993; published online 28 December 2007.

SHP-1 deficiency and increased inflammatory gene expression in PBMCs of multiple sclerosis patients

Recent studies in mice have demonstrated that the protein tyrosine phosphatase SHP-1 is a crucial negative regulator of cytokine signaling, inflammatory gene expression, and demyelination in central nervous system. The present study investigates a possible similar role for SHP-1 in the human disease multiple sclerosis (MS). The levels of SHP-1 protein and mRNA in PBMCs of MS patients were significantly lower compared to normal subjects. Moreover, promoter II transcripts, expressed from one of two known promoters, were selectively deficient in MS patients. To examine functional consequences of the lower SHP-1 in PBMCs of MS patients, we measured the intracellular levels of phosphorylated STAT6 (pSTAT6). As expected, MS patients had significantly higher levels of pSTAT6. Accordingly, siRNA to SHP-1 effectively increased the levels of pSTAT6 in PBMCs of controls to levels equal to MS patients. Additionally, transduction of PBMCs with a lentiviral vector expressing SHP-1 lowered pSTAT6 levels. Finally, multiple STAT6-responsive inflammatory genes were increased in PBMCs of MS patients relative to PBMCs of normal subjects. Thus, PBMCs of MS patients display a stable deficiency of SHP-1 expression, heightened STAT6 phosphorylation, and an enhanced state of activation relevant to the mechanisms of inflammatory demyelination.