Detection of Merkel cell polyomavirus with a tumour-specific signature in non-small cell lung cancer.

BACKGROUND: We searched for a viral aetiology for non-small cell lung cancer (NSCLC), focusing on Merkel cell polyomavirus (MCPyV). METHODS: We analysed 112 Japanese cases of NSCLC for the presence of the MCPyV genome and the expressions of RNA transcripts and MCPyV-encoded antigen. We also conducted the first analysis of the molecular features of MCPyV in lung cancers. RESULTS: PCR revealed that 9 out of 32 squamous cell carcinomas (SCCs), 9 out of 45 adenocarcinomas (ACs), 1 out of 32 large-cell carcinomas, and 1 out of 3 pleomorphic carcinomas were positive for MCPyV DNA. Some MCPyV DNA-positive cancers expressed large T antigen (LT) RNA transcripts. Immunohistochemistry showed that MCPyV LT antigen was expressed in the tumour cells. The viral integration sites were identified in one SCC and one AC. One had both episomal and integrated/truncated forms. The other carried an integrated MCPyV genome with frameshift mutations in the LT gene. CONCLUSION: We have demonstrated the expression of a viral oncoprotein, the presence of integrated MCPyV, and a truncated LT gene with a preserved retinoblastoma tumour-suppressor protein-binding domain in NSCLCs. Although the viral prevalence was low, the tumour-specific molecular signatures support the possibility that MCPyV is partly associated with the pathogenesis of NSCLC in a subset of patients.

Intracellular localization of tyrosine kinase substrates beneath crosslinked surface immunoglobulins in B cells.

Crosslinking of surface immunoglobulins (sIg) in B cells led to the accumulation of submembranal phosphotyrosine, which was followed morphologically with the PY20 antiphosphotyrosine monoclonal antibody. Phosphotyrosine was not detected before sIg crosslinking. After sIg crosslinking, phosphotyrosine-containing proteins were redistributed from scattered small clusters near the plasma membrane to a juxtanuclear region, where immunofluorescent staining decreased with time. Double immunofluorescent staining of individual cells showed accumulation of phosphotyrosine beneath crosslinked sIg molecules at the cell surface. The sIg molecules were subsequently internalized more rapidly than the phosphotyrosine-containing molecules were redistributed. Genistein, a protein tyrosine kinase (PTK) inhibitor, blocked intracellular tyrosine phosphorylations but not cell surface patching of crosslinked sIg. When polyacrylamide beads coated with anti-Ig antibodies were added to the cells, intracellular tyrosine phosphorylation occurred beneath the regions of contact with the beads. This study provides an independent line of evidence confirming recent biochemical experiments that show that crosslinking of the antigen receptor induces PTK activity in B cells, and that components of the newly described sIg complex are among the PTK substrates. The surprising finding that the bulk of the induced phosphotyrosine remains associated with crosslinked sIg for many minutes suggests a role for complex local protein interactions in phosphotyrosine-mediated signal transduction through the antigen receptor of B cells.

An Asian variant of intravascular lymphoma: unique clinical and pathological manifestation in the gallbladder.

We here present a rare case of intravascular lymphoma (IVL) in a Japanese man. 4 months after cholecystectomy due to cholecystitis, a diagnosis of intravascular lymphoma (IVL) was strongly suspected. Lymphoma cells were diffusely observed in the bone marrow parenchyma, but were absent in the vascular spaces. The patient died of respiratory failure and at autopsy a small number of lymphoma cells in the extravascular parenchyma of the adrenal gland and bone marrow were seen. Serial sections of the surgically resected gallbladder retrospectively confirmed the diagnosis of IVL. In addition, congestion and edema were observed in the connective tissue layer. It is possible that edema or ischemia in the gallbladder wall or at other anatomic sites due to the circulation disturbance induced by the intravascular obstruction of lymphoma cells may have caused the initial symptoms. In conclusion, clinicians and pathologists should keep in mind that the gallbladder may be initially involved in IVL.

Different breakage-prone regions on chromosome 1 detected in t(11;14)-positive mantle cell lymphoma cell lines and multiple myeloma cell lines are associated with different tumor progression-related mechanisms.

To better define secondary aberrations that occur in addition to translocation t(11;14)(q13;q32) in mantle cell lymphomas (MCL) and in multiple myelomas (MM), seven t(11;14)-positive MCL cell lines and four t(11;14)-positive MM cell lines were analysed by fluorescence R-banding and spectral karyotyping (SKY). Compared with published data obtained by G-banding, most chromosome aberrations were redefined or further specified. Furthermore, several additional chromosome aberrations were identified. Thus, these cytogenetically well defined t(11;14)-positive MCL and MM cell lines may be useful tools for the identification and characterization of genes that might be involved in the pathogenesis of MCL and MM, respectively. Since MCL and MM were found to have different alterations of chromosome 1, these were investigated in more detail by fluorescence in situ hybridization (FISH) and multicolor banding (MCB) analyses. The most frequently altered and deletion-prone loci in MCL cell lines were regions 1p31 and 1p21. In contrast, breakpoints in MM cell lines most often involved the heterochromatic regions 1p12-->p11, and the subcentromeric regions 1q12 and 1q21. These data are in accordance with previously published data of primary lymphomas. Our findings may indicate that different pathways of clonal evolution are involved in these morphologically distinct lymphomas harboring an identical primary chromosome aberration, t(11;14).

Bridging necrosis and reticulin bridging fibrosis induced by intrahepatic involvement of acute biphenotypic leukemia.

A 47-year-old Japanese woman was diagnosed as having acute biphenotypic leukemia with association of t(9;22)(q34;q11). Cholestatic liver dysfunction arose, and she died of cachexia and intracranial hemorrhage. Autopsy showed unusual hepatic fibrosis. In the liver, bridging infiltration, bridging necrosis and bridging fibrosis by leukemic cells were seen. It seemed that the degree of fibrosis was associated with the number of aggregates of infiltrating leukemic cells. The fibrotic foci were predominantly composed of reticulin and collagen fibers, and distortion of the lobules was observed. Immunohistochemically, dense bundles of alpha-smooth muscle actin (ASMA)-positive stromal cells, namely activated hepatic stellate cells (HSCs), were observed in the immature fibrotic foci as well as along the sinusoids densely infiltrated by leukemic cells. No cells positive for TGF-beta1 or PDGF-BB were identified. In conclusion, extensive intrahepatic involvement by neoplastic cells in adult acute biphenotypic leukemia may cause the unusual "disorganized" hepatic fibrosis.

Angioimmunoblastic lymphadenopathy with disseminated human herpesvirus 6 infection in a patient with acute myeloblastic leukemia.

A 47-year-old man with acute myeloblastic leukemia (AML) developed angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) 4 months after induction chemotherapy for AML. During a leukopenic period, the patient suffered from pericarditis with massive pericardial effusion in which human herpesvirus 6 (HHV-6) DNA was detected. Although complete remission of AML was achieved, fever persisted and atypical skin rash followed by generalized lymphadenopathy along with polyclonal hypergammaglobulinemia appeared. A diagnosis of AILD was made on a biopsy specimen of the inguinal lymph node. The patient died of fulminant hepatitis and the autopsy showed lymphomatous infiltrates involving the liver, bone marrow, lungs, spleen, kidneys and heart. HHV-6 DNA sequences were identified in the biopsy specimen of the lymph node and in the involved organ tissues. HHV-6 in this patient was variant B. It is known that HHV-6 can be reactivated in immunocompromised patients and causes severe complications. This unusual clinical course suggests that the immunosuppression associated with AML and the additional iatrogenic immunosuppression following cytopenia-inducing chemotherapy predisposed the patient to reactivated HHV-6 infection. The sequential detection of this virus before and after manifestation of AILD may support the evidence that HHV-6 infection could directly or indirectly trigger AILD. This is the first time that such a sequence of events has been reported to our knowledge. The possibility of HHV-6 infection should be considered when unexplained fever and generalized lymphadenopathy are seen in patients with leukemia, and administration of antiviral agents should be considered for the diagnostic evaluation.

Analysis of the Smad2 gene in hematological malignancies.

A total of 34 leukemia and lymphoma samples (17 clinical samples and 17 cell lines) were analyzed for mutations of the Smad2 gene by reverse transcriptase-polymerase chain reaction single strand conformation polymorphism (RT-PCR-SSCP) analysis. Nine of the 34 samples had 18q chromosomal abnormalities. No shifted bands were detected in any of the hematological malignancies. Our results suggest that resistance to cell growth inhibitory effects of TGF-beta in hematological malignancies is not due to alterations of the Smad2 gene.

Gastric lymphoma associated with human T-cell leukemia virus type I.

A 41-year-old woman presented with a gastric lymphoma. A total gastrectomy was performed, and the tumor was found to consist of T cells of the helper/inducer (E+, Leu-1+, Leu-2a-, Leu-3a+) phenotype. The patient was seropositive for T-cell leukemia virus type I, and the tumor cells contained the proviral genome.

More efficient peptide binding to MHC class II molecules during cathepsin B digestion of Ii than after Ii release.

The binding of a T cell-presented peptide to MHC class II alpha,beta chains occurs as a concurrent process with the release of the associated invariant chain (Ii) by cathepsin B. Ii was digested by cathepsin B from solubilized, MHC class II alpha,beta,Ii complexes in the presence of N-hydroxysuccinimidyl-4-azidobenzoate-conjugated, 125I-labeled, influenza virus matrix (18-29) peptide. The peptide was crosslinked where it became bound. This HLA-DR1-restricted peptide bound about three times more efficiently to class II alpha,beta chains of DR1-positive B cells when present during cathepsin B digestion of Ii than when added afterward, also at pH 5.0. Binding was competed by similarly DR-restricted peptides. Cathepsin D cleaved Ii but did not enhance peptide binding. However, a trace level of cathepsin D, added to the assay for peptide binding in the presence of cathepsin B, further enhanced peptide binding about three times. These experiments support an hypothesis for the staged release of Ii fragments by cathepsin D and cathepsin B, catalyzing at one point the insertion of a peptide into the antigen binding site formed by class II alpha and beta chains.

Cathepsin B cleavage and release of invariant chain from MHC class II molecules follow a staged pattern.

A staged pattern of cathepsin B cleavage of MHC class II alpha, beta-bound invariant (Ii) chain and release of fragments was defined. Charge-loss mutations in the Ii chain were created in three clusters of cathepsin B putative cleavage sites R78K80K83K86, K137K143, and R151K154. Products of HLA-DR1 alpha, beta and wild type (WT) or mutant Ii genes, co-transfected into COS1 cells, were cleaved by cathepsin B and immunoprecipitated by antibodies either to MHC class II chains or to different Ii epitopes. In WT Ii, cathepsin B digestion generated two forms of p21 Ii fragments: a p21 recognized by anti-C-terminus antibodies and a p21 recognized by an antibody to a determinant near the N-terminus. C-terminal p21 was released from MHC class II alpha, beta chains upon its formation while N-terminal p21 remained associated with MHC class II alpha, beta chains. Mutations at K137K143 inhibited the generation of N-terminal p21 by cathepsin B. Mutation at R78K80K83K86 led to an accumulation of MHC class II-bound N-terminal p21 without the appearance of MHC class II-bound p14, p10, and p6 fragments after cathepsin B digestion. These results indicate that cathepsin B cleaves wild type Ii first about K137K143 to produce a MHC class II-associated N-terminal p21, which is then cleaved about R78K80K83K86 to generate p14, p10 and finally p6 which still associates with MHC class II alpha, beta chains. This pattern of staged cleavage and release of Ii might be related to a concerted mechanism regulating the binding of antigenic peptides to MHC class II molecules.

Co-infection of HHV-6 and HHV-8 is rare in primary effusion lymphoma.

The presence and distribution of Epstein-Barr virus (EBV), as well as human herpesvirus-6 and-8 (HHV-6 and HHV-8) was investigated by polymerase chain reaction in 191 samples from a variety of lymphoproliferative disorders. HHV-6 DNA was detected in 18% (30 of 169) of non-HHV-8 related lymphoproliferative disorders, with the highest frequency in AIDS-related lymphomas (8 of 25, 32%). In contrast, HHV-6 DNA was present in less than 5% (1 of 22) of HHV-8 related lymphoproliferative disorders [21 primary effusion lymphomas (PEL), and 1 cases of Castleman disease]. As compared to HHV-6, EBV DNA was frequently detected in PEL (11 of 19 samples, 58%). This study suggests that transformation to PEL is not enhanced by HHV-6, furthermore HHV-6 and -8 may interfere with each other.

Constitutional t(3;11)(p21;q23) in a family, including one member with lymphoma: establishment of novel cell lines with this translocation.

We describe a family with an inherited constitutional chromosome translocation (3;11) (p21;q23). Of three proven translocation carriers, one had duodenal malignant lymphoma (B-cell diffuse lymphoma, medium-sized cell type). The t(3;11)(p21;q23) was detected not only in hematopoietic cells including the patient's lymphoma cells, non-pathological bone marrow, and phytohemagglutinin-stimulated peripheral blood, but also in fibroblasts of the skin. We have successfully established an Epstein-Barr virus-transformed B-cell line and a Herpesvirus saimiri-transformed T-cell line from the patient, and found that both cell lines also carried this translocation. The patient's asymptomatic mother and sister had the same chromosomal abnormality. Chromosomal abnormalities of the 11q23 band occur frequently in various hematopoietic malignant disorders, and 3q21 has been linked to the pathogenesis of several solid tumors including carcinomas of the kidney, lung, and breast. Although 11q23 is known to recombine with many different chromosomal segments, t(3;11)(p21;q23) has not been reported to our knowledge. Further assessment is warranted to clarify if this constitutional translocation predisposes to certain malignancies. Our cell lines carrying the novel chromosome translocation would be useful for the molecular analysis of the rearranged genes involving both 3p21 and 11q23.

Human herpesviruses in primary ocular lymphoma.

Several human lymphotropic herpesviruses have been found in certain lymphoproliferative disorders and implicated as possible etiologic factors or as modulating elements of the diseases. To assess a possible association of the human herpesviruses with lymphomas arising from mucosa-associated lymphoid tissue (MALT), we evaluated the presence of four human herpesviruses, Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), HHV-7, and HHV-8, in the biopsied specimens from 14 patients with primary ocular MALT lymphomas. EBV DNA sequences were detected in four specimens by polymerase chain reaction (PCR), and four cases were positive for HHV-6 DNA. In situ hybridization showed that three and two of 14 cases were positive for EBV mRNA and HHV-6 DNA, respectively. Neither HHV-7 nor HHV-8 sequences could be detected by PCR. These findings would stimulate further investigation as to the involvement of these lymphotropic viruses in the pathogenesis of a subset of low-grade primary ocular lymphomas.

[Human herpesvirus 6(HHV-6) and HHV-8 in malignant lymphoma].

Over the past 14 years three new human herpesviruses(HHV-6, -7 and -8) have been recognized and implicated as etiological agents of several human diseases. HHV-6 has been cited as a possible cause or as a modulating element of certain human lymphoproliferative disorders, particularly malignant lymphomas including Hodgkin's disease and Burkitt's lymphoma. Despite the genomic homology and serological cross-reactivity between HHV-6 and HHV-7, evidence for the association of HHV-7 with lymphoproliferative diseases has been scarce. HHV-8 was originally found in patients with Kaposi's sarcoma, and subsequently shown to be implicated in primary effusion lymphoma(PEL), a novel lymphoma entity. We found that HHV-6 genome is integrated into host DNA of lymphoma cells. Further studies are warranted to determine whether chromosomally integrated HHV-6 has any role in the pathogenesis of viral genome-positive lymphoproliferative diseases.