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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Basal cell carcinoma (BCC) is typically a slow-growing malignant tumour, composed of cells similar to those in the basal area of the epidermis. We investigated the expression of bcl-2 (B-cell leukaemia/lymphoma-2) in BCC, and also in squamous cell carcinoma (SCC) of the skin. The proto-oncogene bcl-2 encodes a protein which inhibits programmed cell death (apoptosis). The protein is expressed in basal cells in normal human epithelium, but not in the suprabasal cell layers. Immunohistochemical localization using a monoclonal anti-Bcl-2 antibody revealed bcl-2 expression in all the BCCs (15 patients). SCCs did not express bcl-2 (five patients). The positive Bcl-2 staining of BCC tumour cells supports the hypothesis that BCCs originate from the basal layer of the epidermis. The bcl-2 expression of BCC tumour cells also suggests a neoplastic transformation caused by extended cell survival rather than increased cell proliferation. This type of neoplastic growth is possibly associated with less aggressive tumour behaviour.
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PMID:Expression of the apoptosis-suppressing protein Bcl-2 in non-melanoma skin cancer. 777 78

Programmed cell death is a controlled process that leads to the elimination of single cells via apoptosis, a mode of cell death with a characteristic morphology. During epidermal differentiation, keratinocytes migrate outward to become terminally differentiated cornified cells in a process involving programmed cell death pathway(s) and apoptosis. The molecular mechanisms regulating epidermal differentiation and apoptosis have not yet been elucidated. Here we show that a mouse keratinocyte cell line, Pam212, undergoes spontaneous apoptosis in culture. Apoptosis of Pam212 cells is demonstrated by both morphology and DNA oligonucleosomal degradation. The expression of bcl-2, a gene implicated in the negative control of apoptosis, was down-regulated in these cells by transfecting a bcl-2-antisense expression vector. The cells that down-regulate bcl-2 expression exhibit enhanced apoptosis and further progress in the epidermal differentiation pathway. We analyzed the expression patterns of several genes that have been implicated in apoptosis in other systems. We show that the mRNA levels of c-myc, c-myb, c-fos, tumor necrosis factors (TNF) alpha and beta, TNF receptors I and II, interleukin 1 alpha, IFN-gamma, and transforming growth factor beta increase in the antisense-transfected cells. We suggest that bcl-2 influences epidermal differentiation in Pam212 keratinocyte cells, and maybe in vivo, by negatively regulating several genes that are involved in apoptosis.
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PMID:Apoptosis in Pam212, an epidermal keratinocyte cell line: a possible role for bcl-2 in epidermal differentiation. 779 92

The apoptotic cells in situ of normal tissues and human brain tumors were analyzed by the modified method of TUNEL, and the relationship between the localization of apoptotic cells and the expression of bcl-2 protein was examined. The localization of apoptotic cells in normal tissue was situated at fast renewing tissues, and differed from the localization of the expression of bcl-2 protein. In the cases of medulloblastoma, 7 out of 8 cases (87.5%) showed apoptotic cells. In contrast to the results of high frequency of apoptotic cells in medulloblastoma and germinoma, the expression of bcl-2 protein was found very low incidence in those tumors, which were thought to be sensitive against radiation or chemotherapy. These results suggested that the detection of apoptosis in situ by this method could predict the sensitivity of radiation or chemotherapy of the tumor cells.
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PMID:Localization of apoptotic cells in situ of brain tumors. 779 25

The bcl-2 protooncogene was initially discovered at the t(14;18) chromosomal breakpoint in follicular lymphomas. It has been demonstrated that bcl-2 protein (Bcl-2) expression blocks apoptosis and plays an important role in cell development and maturation. In the present study, Bcl-2 expression was immunohistochemically examined in 103 cases of gastric carcinoma, as well as 64 cases of non-carcinous gastric mucosa, and its correlation with apoptosis, cell proliferation and p53 immunoreactivity was investigated. Bcl-2 was detected in 18.0% of differentiated-type gastric carcinomas (9 of 50) and 7.5% of the undifferentiated type (4 of 53). In adjacent intestinal metaplastic gastric epithelium, the incidence of Bcl-2 positivity in the incomplete type (21/23, 91.3%) was significantly higher than in the complete type (23/41, 56.1%) (P < 0.04). Double immunostaining for Bcl-2 and Ki-67 clearly revealed the majority of Bcl-2-positive cancer cells to be in a nonproliferating state, although some cancer cells expressed both proteins together. Statistical assessment demonstrated that the average Ki-67 labeling index and apoptotic labeling index in Bcl-2-positive foci were significantly lower than in Bcl-2-negative foci (P < 0.0001, P < 0.0003). In addition, a significant dissociation between Bcl-2 and p53 immunoreactivity was found in cancer tissues. These results indicate that aberrant Bcl-2 expression in gastric carcinomas possibly originates from intestinal metaplastic epithelium, and suggest a possible role in tumor development and growth.
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PMID:Bcl-2 expression and its association with cell kinetics in human gastric carcinomas and intestinal metaplasia. 779 1

We investigated 34 cases of T-cell neoplasm [15 cases of T-cell granular lymphocytic leukemia (T-GLL), 10 cases of T-cell non-Hodgkin's lymphoma (T-NHL), six cases of T-cell chronic lymphocytic leukemia (T-CLL), and three cases of cutaneous T-cell lymphoma] to study their association with Epstein-Barr virus (EBV). In 4 (three T-NHL and one T-GLL) of 34 cases, EBV genome was detected in a single episomal form, while polyclonal EBV-DNA was detected in one (T-NHL) of the remaining cases. All three cases of T-NHL having monoclonal EBV episome showed histologically diffuse large-cell lymphoma and developed leukemic conversion. Phenotypic analysis showed that two of these four cases were CD4+, CD8-, and the remaining two cases were CD4-, CD8+. The cells from all four cases were confirmed to be in T-cell lineage by detecting the rearrangement of T-cell receptor (TCR) beta or gamma chain gene. By reverse transcription-polymerase chain reaction (RT-PCR), EBNA-1 was detected at low levels, and neither EBNA-2 nor LMP-1 were found in any of the three cases examined. Lack of the expression of EBNA-2 and LMP-1 was also confirmed by immunocytochemical staining. The cells of these four cases did not show rearrangement or overexpression of c-myc and bcl-2 genes by Southern and Northern blots, and the mutation of p53 gene was detected in only one patient. These results suggest that other latent gene products of EBV or other cellular oncogenes are involved in the development of Japanese T-cell neoplasm after EBV infection.
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PMID:Lack of the expression of EBNA-2 and LMP-1 in T-cell neoplasms possessing Epstein-Barr virus. 781 2

The posttransplantation lymphoproliferative disorders (PT-LPDs) are a morphologically heterogeneous group of Epstein-Barr virus (EBV)-driven lymphoid proliferations of varying clonal composition. Some PT-LPDs regress after a reduction in immunosuppression, while others progress in spite of aggressive therapy. Previously defined morphologic categories do not correlate with clonality, and neither morphology nor clonality has reliably predicted the clinical behavior of PT-LPDs. We investigated 28 PT-LPD lesions occurring in 22 patients for activating alterations involving the bcl-1, bcl-2, c-myc, and H-, K- and N-ras proto-oncogenes and for mutations involving the p53 tumor suppressor gene. We correlated the results of these studies with the morphology of the lesions, their clonality based on Ig heavy and light chain gene rearrangement analysis, and the presence and clonality of EBV infection. We found that the PT-LPDs are divisible into three distinct categories as follows: (1) plasmacytic hyperplasia: most commonly arise in the oropharynx or lymph nodes, are nearly always polyclonal, usually contain multiple EBV infection events or only a minor cell population infected by a single form of EBV, and lack oncogene and tumor suppressor gene alterations; (2) polymorphic B-cell hyperplasia and polymorphic B-cell lymphoma: may arise in lymph nodes or various extranodal sites, are nearly always monoclonal, usually contain a single form of EBV, and lack oncogene and tumor suppressor gene alterations; and (3) immunoblastic lymphoma or multiple myeloma: present with widely disseminated disease, are monoclonal, contain a single form of EBV, and contain alterations of one or more oncogene or tumor suppressor genes (N-ras gene codon 61 point mutation, p53 gene mutation, or c-myc gene rearrangement). The PT-LPDs are divisible into three categories exhibiting distinct morphologic and molecular genetic characteristics. Alterations involving the N-ras and c-myc proto-oncogenes and the p53 tumor suppressor gene may play an important role in the development and/or progression of the PT-LPDs.
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PMID:Correlative morphologic and molecular genetic analysis demonstrates three distinct categories of posttransplantation lymphoproliferative disorders. 781 11

Although T-cell-rich B-cell lymphoma (TCRBCL) is a recently recognized form of non-Hodgkin's lymphoma (NHL), limited information regarding its incidence, cellular origin, morphologic spectrum, and biologic behavior is currently available. In this study, the clinicopathologic features of eight patients with TCRBCL are presented. This neoplasm comprised about 1% of all NHLs seen at Emory University Hospital over 2 years. The male-to-female ratio was 1.6, and the mean age at diagnosis was 60 years. At presentation, TCRBCL was nodal in 88% of the patients and widely disseminated in 50% of the patients. A complete remission was seen in three of the five patients treated with combination chemotherapy that was directed at intermediate grade NHL. Three patients received inadequate or incomplete chemotherapy. One of these patients later achieved a complete remission with more intensive therapy. Two of the patients were not evaluable for response to therapy. The actuarial and disease-free survival rates of the group at 5 years were 72% and 21%, respectively. Morphologically, the lymph nodes in seven of eight cases were diffusely obliterated, whereas one had markedly expanded interfollicular zones that lead to an initial diagnosis of T-zone lymphoma. All tumors were characterized by no more than 25% large lymphoid cells, which were scattered in a background of small lymphocytes with round or irregular nuclei. The presence of numerous histiocytes imparted a lymphoepithelioid appearance in two cases. Although immunoperoxidase stains of frozen tissue were initially suggestive of a peripheral T-cell lymphoma in some cases, paraffin immunoperoxidase stains clearly established the B-cell nature of the large cells, whereas most of the small cells were T lymphocytes. The clonal nature of the large cells was confirmed in seven cases by monotypic immunoglobulin (Ig) light chain restriction or Ig gene rearrangements. Epstein-Barr virus genomic DNA was detected in two of the six cases tested by polymerase chain reaction or Southern blot analysis, but no evidence of a bcl-2 rearrangement was found in any of the five cases examined. These findings indicate that TCRBCL is an uncommon form of NHL with a therapeutic response and overall survival consistent with intermediate grade lymphoma. Paraffin immunoperoxidase stains and occasionally genotypic analysis are required to exclude the diagnosis of PTCL or diffuse lymphocyte predominant Hodgkin's disease. The authors found no morphologic or molecular evidence to support a follicular center cell origin in these cases of TCRBCL.
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PMID:T-cell-rich B-cell lymphoma. A clinicopathologic study of eight cases. 781 42

The realization that malignant tumors may grow not only due to proliferation but also because cells don't die when they should provides absolute new directions in basic and clinical tumor research. Thus, apoptosis, the programmed cell death is very hot now in the scientific community. In the center of interest are the regulation mechanisms of apoptosis and its significance in different tumor entities. Recently, numerous studies on apoptosis during embryogenesis, different stages of tissue development and in epithelial and hormone dependent tumors have been published. The data suggested an important role of bcl-2 in regulation of apoptosis. In this view the demonstration of bcl-2 oncogene expression in osteosarcoma, a mesenchymal tumor, is of potential great interest.
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PMID:[Apoptosis: bcl-2 as a key protein for programmed cell death]. 785 1

We report overexpression of the proto-oncogene bcl-2 in gastrointestinal adenocarcinoma and its precursor lesions. The bcl-2 proto-oncogene is centrally involved in the oncogenesis of human follicular lymphoma via a chromosomal translocation t(14;18)(q32;q21) and is also expressed in the epithelial regenerative compartment or the basal crypts of the normal colon and small intestine. We describe an immunohistochemical analysis of fixed, paraffin-embedded tissue using both a polyclonal rabbit and a monoclonal mouse antibody to the Bcl-2 protein. In addition to confirming bcl-2 expression in normal colonic and small intestinal crypts, we also observed expression in the gastric epithelial regenerative compartment, the mucous neck region. No increased expression was found in nonneoplastic or inflammatory gastrointestinal conditions, including ulcerative colitis, Crohn's disease, or inflammatory or hamartomatous polyps. Increased bcl-2 expression, however, was present in hyperplastic colonic polyps and in the majority of dysplastic lesions, from the earliest precursors through large adenomas, high grade flat dysplasia, and adenocarcinoma, all in comparison with adjacent internal control normal epithelium. Increased expression was present in dysplastic glandular lesions from all gastrointestinal sites, including colon, small bowel, and stomach. Furthermore, bcl-2 expression was frequently abnormal in nondysplastic epithelium surrounding dysplastic lesions, suggesting that altered expression occurred before the development of morphological dysplasia. Specifically, directly contiguous morphologically nondysplastic epithelium often showed abnormal bcl-2 expression throughout the full length of the crypt-villus axis. This expression pattern gradually diminished to involve only the crypt base (the normal pattern of expression), proceeding away from malignant or dysplastic lesions. Abnormal bcl-2 immunoreactivity in 1), the earliest precursor dysplastic lesions and its persistence throughout neoplastic progression and 2), contiguous morphologically unaltered nondysplastic epithelium suggests that bcl-2 alterations occur early during the morphological and molecular sequence of events leading to gastrointestinal epithelial neoplasia.
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PMID:The bcl-2 proto-oncogene and the gastrointestinal epithelial tumor progression model. 785 28

bcl-2 protein (BCL-2) expression was immunohistochemically studied in 140 varied central nervous system tumors. The protein was most frequently expressed in neurinomas and ependymomas, and in normal ependymal cells and Schwann cells. Most pituitary adenomas could be classified into one of two subgroups, diffusely positive or diffusely negative tumors, while BCL-2 localized heterogeneously in normal pituitary glands. Although the protein was not detected in normal astrocytes, it was positive in reactive hypertrophic astrocytes observed in various pathological conditions. Similarly, astrocytic tumor cells often expressed BCL-2. Since low-grade astrocytomas more often exhibited the protein than malignant gliomas, the degree of BCL-2 expression appeared to be related to the degree of malignancy of the gliomas. On the other hand, 7 out of 17 recurrent gliomas and medulloblastomas showed an increase in the frequency of protein expression compared with specimens from initial treatments. One recurrent astrocytic tumor which demonstrated anaplastic change showed a decrease in the frequency of BCL-2-positive cells. It is concluded that the frequency of BCL-2 expression in CNS tumors is increased when the non-neoplastic counterparts of the tumors exhibit the protein. Although it has been reported that overexpression of BCL-2 protects cells from damage by radiation and/or chemotherapy, we could not find any significant relationship between the degree of BCL-2 expression and the length of survival of patients with glioblastomas or medulloblastomas.
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PMID:bcl-2 protein expression in tumors of the central nervous system. 787 98


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