Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

BK virus (BKV) is a member of the polyomavirus family that persistently infects 75-80% of the human population. BKV encodes a large T antigen which is responsible for the transforming functions of the virus. Recent studies have shown an association of BKV DNA with a variety of human tumours including pancreatic islet, brain, urinary tract and Kaposi's sarcoma. Despite the detection of BKV DNA in several human tumours, there is no clear evidence for a causative role in tumour formation. We have sought to characterize the interactions of BKV TAg with cellular tumour suppressor proteins including p53, pRb, p107, and p130 in an attempt to further understand the molecular mechanisms of transformation by BKV. We have shown that BKV TAg can bind to and functionally inhibit p53 and the p53-mediated response to DNA damage. Additionally, we have shown that low levels of BKV TAg are sufficient to induce free E2F and a serum-independent phenotype despite the absence of detectable interactions with pRb family members. Taken together, these results suggest that BKV TAg can both inhibit the cellular response to DNA damage and induce proliferation, allowing for potential accumulation of mutations in cellular growth control genes. These results suggest a possible role for BKV TAg in cellular transformation and tumour formation in the human host.
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PMID:BK virus as a potential co-factor in human cancer. 977 29

The aim of this study was the evaluation of p53/MDM-2 protein overexpression in different subtypes of human sarcomas, and their correlation with proliferative activity and patient outcome. We selected 40 cases of human sarcomas comprising 6 malignant fibrous histiocytomas (MFH), 1 fibrosarcoma, 1 dermatofibrosarcoma protuberans, 5 liposarcomas, 9 leiomyosarcomas, 1 rhabdomyosarcoma, 3 synovial sarcomas, 2 osteosarcomas, 1 chondrosarcoma, 4 Ewing's sarcomas, 2 Kaposi's sarcomas, 1 malignant haemangiopericytoma, 1 phylloides cystosarcoma, 1 neuroblastoma, 1 chordoma and 1 unclassified sarcoma. All the immunohistochemical markers, which had been used for the characterization of these sarcomas were re-examined. Additionally, the Streptavidin-Biotin peroxidase method was performed on paraffin sections using the monoclonal antibodies: anti-p53 antibody DO7, anti-MDM-2 antibody IF2 and anti-Ki-67 antibody MIB-1. According to our results, p53 protein nuclear expression was detected in 20% (8/40) of the tumours (1 fibrosarcoma, 2 liposarcomas, 1 leiomyosarcoma, 1 rhabdomyosarcoma, 2 Ewing's sarcomas and 1 unclassified sarcoma). MDM-2 nuclear staining was determined in 7.5% (3/40) of the cases (1 MFH and 2 liposarcomas). A high proliferative index was demonstrated in 27.5% (11/40) of the tumours (2 MFH, 4 leiomyosarcomas, 1 rhabdomyosarcoma, 1 osteosarcoma, 2 Ewing's sarcomas and 1 unclassified sarcoma). p53 overexpression was associated with high tumour grade (p < 0.05) and MIB-1 expression was correlated with reduced survival (p < 0.05), but p53 overexpression was not significantly associated with either MIB-1 score or with overall survival of the patients. In conclusion, from this limited and heterogeneous sample of cases, we suggest that the p53/MDM-2 pathway is involved in the tumourigenesis of several sarcoma subtypes, but it is unclear if the overexpression of these genes may become prognostic marker for patients affected with these highly aggressive tumours.
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PMID:p53/MDM-2 immunohistochemical expression correlated with proliferative activity in different subtypes of human sarcomas: a ten-year follow-up study. 989 39

The vast majority of the human experience with viral infections is associated with acute symptoms, such as malaise, fever, chills, rhinitis and diarrhea. With this acute or lytic phase, the immune system mounts a response and eliminates the viral agent while acquiring antibodies to that specific viral subtype. With latent or chronic infections, the viral agent becomes incorporated into the human genome. Viral agents capable of integration into the host's genetic material are particularly dangerous and may commandeer the host's ability to regulate normal cell growth and proliferation. The oncogenic viruses may immortalize the host cell, and facilitate malignant transformation. Cell growth and proliferation may be enhanced by viral interference with tumor suppressor gene function (p53 and pRb). Viruses may act as vectors for mutated proto-oncogenes (oncogenes). Overexpression of these oncogenes in viral-infected cells interferes with normal cell function and allows unregulated cell growth and proliferation, which may lead to malignant transformation and tumour formation. Development of oral neoplasms, both benign and malignant, has been linked to several viruses. Epstein-Barr virus is associated with oral hairy leukoplakia, lymphoproliferative disease, lymphoepithelial carcinoma, B-cell lymphomas, and nasopharyngeal carcinoma. Human herpesvirus-8 has been implicated in all forms of Kaposi's sarcoma, primary effusion lymphomas, multiple myeloma, angioimmunoblastic lymphadenopathy, and Castleman's disease. Human herpesvirus-6 has been detected in lymphoproliferative disease, lymphomas, Hodgkin's disease, and oral squamous cell carcinoma. The role of human papillomavirus in benign (squamous papilloma, focal epithelial hyperplasia, condyloma acuminatum, verruca vulgaris), premalignant (oral epithelial dysplasia), and malignant (squamous cell carcinoma) neoplasms within the oral cavity is well recognized. Herpes simplex virus may participate as a cofactor in oral squamous cell carcinoma development by enhancing activation, amplification, and overexpression of pre-existing oncogenes within neoplastic tissues. Because of the integral role of viruses in malignant transformation of host cells, innovative antiviral therapy may prevent tumour development, involute neoplastic proliferations, or arrest malignant progression.
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PMID:Molecular piracy: the viral link to carcinogenesis. 993 Mar 54

A recently identified herpesvirus, human herpesvirus-8 (HHV-8), also known as Kaposi's sarcoma (KS)-associated herpesvirus, has been found in nonmalignant bone marrow dendritic cells of patients with multiple myeloma. The virus is also detectable in the peripheral blood of most patients; its absence suggests earlier-stage disease. HHV-8 is not detected in the blood of family members and sexual partners of myeloma patients. Sequencing of HHV-8 open-reading frames (ORFs) shows differences between individual myeloma patients, as well as between myeloma patients and those with other HHV-8-related malignancies. Consistent expression of the viral homolog of both interferon regulatory factor (IRF) and interleukin-8 receptor (IL-8R) suggests a possible role for these transforming viral genes in the pathogenesis of myeloma. Detailed analysis of myeloma cell lines has shown that myeloma is characterized by frequent chromosome translocations involving the switch regions of the immunoglobulin heavy-chain (IgH) locus on 14q32. The three partner chromosomes most commonly involved are 11q13 (cyclin D1), 4p16 (FGFR3), and 16q23 (c-maf). Mutations have also been identified in N- and K-ras and, less frequently, involving p53. Monosomy 13q is common. These findings have implications for immunotherapy. Angiogenesis increases with progressive disease and appears to be a prognostic factor. In at least one patient, this process appears to have been reversed with thalidomide therapy. The underlying mechanisms for the increased vascularization in myeloma have not been identified, and several possibilities have been proposed.
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PMID:Initiation and maintenance of multiple myeloma. 998 83

Seventy three cases of Kaposi's sarcoma (KS) from the 3 histological subtypes (patch, plaque and nodular) were assessed for bcl-2 and p53 protein expression. The aim was to determine the level of expression of these proteins in KS and in the different subtypes. Commercially available antibodies to bcl-2 and p53 were applied after both microwave and pressure cooking antigen retrieval. Bcl-2 immunoexpression increased from the patch stage (36%) to the plaque stage (45%) to the nodular stage (70.83%). Better immunostaining for bcl-2 was obtained after pressure cooking. p53 on the other hand, was not expressed in the patch or plaque stages, but 54.16% of cases in the nodular stage were immunopositive. These results show a progression of immunoexpression of both bcl-2 and p53 from the early histological stages to the late tumor stage, implying that these proteins are upregulated late in the evolution of KS.
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PMID:Bcl-2 and p53 immunoprofile in Kaposi's sarcoma. 1007 72

In many neoplasms, the finding p53 immunoreactivity correlates with striking cytologic atypia, a high tumor cell proliferation rate, and poor prognosis. The literature regarding p53 and Ki-67 (a nuclear proliferation-associated antigen) immunoreactivity in Kaposi's sarcoma is limited. We aimed to: (1) evaluate the role of p53 in the development of Kaposi's sarcoma; (2) determine whether there is a correlation between p53 and Ki-67 protein expression; and (3) determine possible differences between classical Kaposi's sarcoma, known usually to have a benign course, and iatrogenic Kaposi's sarcoma, the course of which is unpredictable, by studying the differential expression of p53 and Ki-67. Among 26 cases of classic KS and 19 of iatrogenic KS, 12 were classified histopathologically as early type and 33 as mixed or spindle-cell type. P53 and Ki-67 immunoreactivity correlated significantly with the histopathologic stage of KS (r=0.63, p=0.0001; r=0.42, p=0.0084, respectively). P53 was not detected in any of the cases in an early histopathologic stage but was present in 55% of the cases in a more advanced stage. The spindle cells increased in proportion with the histopathologic progression and were more often positive (p=0.019) and displayed more extensive staining than the endothelial cells (p=0.0001). There was a strong positive correlation between p53 and Ki-67 protein expression (r=0.43, p=0.0087). There was no correlation between the expression of either p53 or Ki-67 and the extent of the eruption. The expression of p53 and Ki-67 was significantly lower in iatrogenic cases than in the classic cases (p=0.009, p=0.0014, respectively), although no statistical difference was found between the histopathologic stages in the two clinical forms of KS. P53 immunoreactivity was detected in 79% of the cases of classic Kaposi's sarcoma in the mixed or spindle cell stage but in only 21.5% of the iatrogenic cases showing the same histopathologic stage (p=0.001), and the percentage of spindle cells as well as the endothelial cells expressing p53 was higher in the classic cases than in the iatrogenic cases (p=0.0032, p=0.0142, respectively). We conclude that p53 immunoexpression is a marker of tumor progression in classic Kaposi's sarcoma but not in most cases of iatrogenic Kaposi's sarcoma. The proliferative activity of the tumor cells in classic Kaposi's sarcoma is much higher than in iatrogenic Kaposi's sarcoma. Our work implies that the molecular steps involved in classic and iatrogenic Kaposi's sarcoma differ.
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PMID:Differential expression of p53 and Ki-67 proteins in classic and iatrogenic Kaposi's sarcoma. 1069 26

Kaposi's sarcoma (KS) is the most frequent malignancy associated with HIV infection (AIDS-KS), a complication that leads to high mortality and morbidity. AIDS-KS cells are resistant to killing by chemotherapeutic drugs/NK cells and Fas-induced apoptosis, suggesting that the acquisition of antiapoptotic characteristics by AIDS-KS cells may contribute to their prolonged survival. Apo-2 ligand (Apo-2L)/TNF-related apoptosis-inducing ligand, a new member of the TNF family, has been identified as an apoptosis-inducing molecule. In this study we examined the sensitivity of 10 different AIDS-KS isolates to Apo-2L-mediated cytotoxicity. AIDS-KS cells were relatively resistant to Apo-2L; however, Apo-2L and actinomycin D (Act D) used in combination synergistically potentiated the induction of cell death in nine of the 10 isolates. Apo-2L induced apoptosis in >80% of AIDS-KS cells pretreated with Act D. The caspase inhibitors, zIETD-fmk and zDEVD-fmk, inhibited apoptosis in AIDS-KS by sApo-2L, suggesting that caspase 3-like and caspase 8 or 10 activities are essential for Apo-2L-mediated apoptosis. Act D treatment of AIDS-KS cells markedly and selectively down-regulated Bcl-xL expression, while the expressions of decoy receptors 1 and 2, Bax, cellular FLICE (Fas-associated death domain protein-like IL-1-converting enzyme) inhibitory protein, FADD (Fas-associated death domain protein), procaspase 8, and p53 were not affected. These findings suggest the possible involvement of Bcl-xL in Act D-induced sensitization of AIDS-KS cells to Apo-2L-mediated apoptosis. Furthermore, Act D did not sensitize PBMC or fibroblast cells to Apo-2L. Thus, Apo-2L and Act D used in combination may be of therapeutic value in the treatment of AIDS-KS.
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PMID:Sensitization of AIDS-Kaposi's sarcoma cells to Apo-2 ligand-induced apoptosis by actinomycin D. 1022 45

Kaposi's sarcoma-associated herpesvirus (KSHV) has a key etiological role in development of Kaposi's sarcoma (KS). v-Cyclin is a KSHV-encoded homologue to D-type cyclins that associates with cellular cyclin-dependent kinase 6 (CDK6). v-Cyclin promotes S-phase entry of quiescent cells and has been suggested to execute functions of both D- and E-type cyclins. In this study, expression of v-cyclin in cells with elevated levels of CDK6 led to apoptotic cell death after the cells entered S phase. The cell death required the kinase activity of CDK6 because cells expressing a kinase-deficient form of CDK6 did not undergo apoptosis upon v-cyclin expression. Studies on the mechanisms involved in this caspase-3-mediated apoptosis indicated that it was independent of cellular p53 or pRb status, and it was not suppressed by Bcl-2. In contrast, the KSHV-encoded v-Bcl-2 efficiently suppressed v-cyclin-/CDK6-induced apoptosis, demonstrating a marked difference in the antiapoptotic properties of c-Bcl-2 and v-Bcl-2. In KS lesions, high CDK6 expression was confined to a subset of cells, some of which displayed signs of apoptosis. These results suggest that v-cyclin may exert both growth-promoting and apoptotic functions in KS, depending on factors regulating CDK6 and v-Bcl-2 levels.
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PMID:Kaposi's sarcoma-associated herpesvirus-encoded v-cyclin triggers apoptosis in cells with high levels of cyclin-dependent kinase 6. 1051 12

We studied 21 HIV-associated lymphomas with cutaneous presentation to determine whether they showed features of primary cutaneous lymphoma arising fortuitously or whether they represented the cutaneous involvement of AIDS systemic lymphoma. Besides rare mycosis fungoides (n = 3), which shared typical clinicopathologic lesions, nonepidermotropic large-cell lymphomas (n = 18) were predominant. They frequently presented as a solitary nodule or tumor. Seven of the eight large T-cell lymphomas had a CD30-positive (CD30+) phenotype but did not express ALK protein. Overexpression of p53 protein was observed in six cases. Although EBV-EBER transcripts were detected in two of them, LMP1 protein was absent. Except for their original prevalence, the features of these T-cell CD30+ cutaneous lymphomas were the same as in immunocompetent patients. The 10 B-cell cutaneous lymphoma were immunoblastic or centroblastic lymphomas, with a differential expression of BCL-6 and Syndecan. Four of them expressed CD30, EBER-EBV transcripts, and LMP1 and p53 proteins. This B-cell CD30+ EBV+ phenotype contrasts with cutaneous lymphoma in immunocompetent patients. Human herpesvirus 8 was not involved in lymphomagenesis since its sequences were detected in a single patient with Kaposi's sarcoma and Castleman's disease. These lymphomas occurred in severely immunocompromised patients with a low CD4 count. Death was due to immunodepression rather than to lymphoma spread, suggesting avoiding aggressive immunosuppressive treatment in such patients.
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PMID:The Spectrum of Cutaneous Lymphomas in HIV infection: a study of 21 cases. 1052 21

Viruses are etiologically linked to approximately 20% of all malignancies worldwide. Retroviruses account for approximately 8%-10% of the total. For human T-cell leukemia virus 1 (HTLV-I), the viral regulatory tax gene product is responsible for enhanced transcription of viral and cellular genes that promote cell growth by stimulating various growth factors and through dysregulation of cellular regulatory suppressor genes, such as p53. After a long latent period, adult T-cell leukemia/lymphoma (ATL) occurs in 1 per 1000 carriers per year, resulting in 2500-3000 cases per year worldwide and over half of the adult lymphoid malignancies in endemic areas. Human immunodeficiency virus 1 (HIV-1) accounts for a significant cancer burden, and its transactivating regulatory protein Tat enhances direct and indirect cytokine and immunological dysregulation to cause diverse cancers. Kaposi's sarcoma (KS) is a very rare tumor except after HIV-1 infection, when its incidence is greatly amplified reaching seventy thousand-fold in HIV-infected homosexual men. Human herpesvirus 8 (HHV-8), which is also known as Kaposi's sarcoma-associated virus (KSHV), is a necessary but not sufficient etiological factor in KS. The dramatic decline of KS since the introduction of highly active antiretroviral therapy (HAART) could be due to suppression of HIV-1 tat. B-cell non-Hodgkin's lymphoma occurs as their first acquired immunodeficiency syndrome-defining diagnosis in 3%-4% of HIV-infected patients. Hodgkin's lymphoma is also associated with HIV infection but at a lower risk. Human papillomaviruses are linked to invasive cervical cancer and anogenital cancers among HIV-infected patients. Human retroviruses cause malignancy via direct effects as well as through interactions with other oncogenic herpesviruses and other viruses.
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PMID:Human retroviruses: their role in cancer. 1059 Oct 85


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