MDM-2 protein expression in nasopharyngeal carcinomas. Comparative study with p53 protein expression

Epstein-Barr Virus in Nasopharyngeal Carcinoma of Guatemalan and Brazilian Patients

BACKGROUND

Nasopharyngeal carcinoma (NPC) is highly associated with Epstein-Barr virus (EBV), particularly the undifferentiated nonkeratinizing subtype. Prevalence of EBV in NPC in countries such as Guatemala and Brazil has not been studied.

METHODS

We analyzed 19 cases of NPC, 11 from Guatemala and 8 from Brazil, for the presence of EBV by in situ hybridization and immunohistochemistry. Additionally, 19 hyperplastic adenoids from children were analyzed for EBV by in situ hybridization, 12 from Guatemala and 7 from Brazil.

RESULTS

All the NPC cases from Guatemala and 5 from Brazil were of the undifferentiated nonkeratinizing type. EBV-negative cases comprised 2 keratinizing NPC and 1 differentiated nonkeratinizing NPC. All undifferentiated nonkeratinizing NPC from both samples showed intense positivity for EBER, while LMP-1 only focally and scarcely expressed. EBER was positive in 75% and 43% of the adenoids from Guatemala and Brazil, respectively.

CONCLUSIONS

All undifferentiated nonkeratinizing NPC irrespective of origin from Guatemala or Brazil were highly associated with EBV.

p53 protein expression in non-Hodgkin's lymphoma. Comparative study with the wild type p53 induced proteins mdm2 and p21/waf1

Aims-To investigate the pattern of expression of p53 protein and two wild type p53 induced proteins (mdm2 and p21/waf1) as an indirect way of assessing p53 gene status in non-Hodgkin's lymphoma.Methods-Formalin fixed, paraffin wax embedded tissue from 87 cases of nodal non-Hodgkin's lymphoma, comprising 52 high grade and 35 low grade tumours, was stained by immunohistochemistry for p53, mdm2 and p21/waf1 proteins.Results-p53, mdm2 and waf1/p21 proteins were expressed in 36/52, 21/52 and 31/52 high grade and 3/35, 21/35 and 3/35 low grade non-Hodgkin's lymphomas, respectively. Parallel p53/mdm2 protein expression was found in 23 cases (21 high grade and two low grade). These 23 cases were also positive for p21/waf1 protein expression. Discordant p53 positive/mdm2 negative protein expression was found in 16 cases (15 high grade and one low grade). Eleven (10 high grade and one low grade) of these 16 cases were p21/waf1 positive and the remaining five high grade non-Hodgkin's lymphomas were p21/waf1 negative. Mdm2 and p21/waf1 proteins were not expressed in the absence of p53 protein expression.Conclusions-p53, mdm2 and waf1/p21 protein expression is more frequently associated with aggressive histotypes of non-Hodgkin's lymphoma. Parallel expression of p53, mdm2 and p21 proteins may represent non-Hodgkin's lymphomas with a wild type p53 gene as mdm2 and p21 proteins can be induced by the wild type gene. In these cases p53 protein expression may result from stabilisation via complex formation with the mdm2 protein. This could be important in the pathogenesis of these cases as mdm2 may deregulate the p53 dependent growth suppressive pathway. Discordant p53 positive/mdm2 negative/p21 negative protein expression may represent non-Hodgkin's lymphoma with p53 gene mutations unable to activate expression of mdm2 and p21 proteins. Non-Hodgkin's lymphoma with p53 positive/mdm2 negative/p21 positive protein expression may have either wild type p53 with deregulated mdm2 gene expression or mutated p53 gene with p53 independent p21 expression.

Epstein-Barr virus-associated high-grade anaplastic plasmacytoma in a renal transplant patient

Allograft transplant patients have an increased risk of developing polyclonal or monoclonal lymphoproliferative disorders, but high-grade anaplastic plasmacytomas are extremely rare in these patients. We present a renal transplant patient who developed multiple extramedullary high-grade anaplastic plasmacytomas in the oral cavity, the left maxillary antrum, the scalp, the thigh and the upper abdominal wall with no evidence of diffuse bone marrow infiltration. Epstein-Barr virus (EBV) mRNA transcripts were detected within the myeloma cells by in situ hybridization using EBER1-2 probes. Following discontinuation of immunosuppression applied, the patient was treated with a cyclophosphamide-prednisone regimen followed by local irradiation, and a complete remission was achieved within four weeks. We concluded that EBV-associated high-grade anaplastic plasmacytomas constitute one more type of post-transplant lymphoproliferative disorder, and that despite their characterization as highly malignant neoplasms, their clinical behavior is not always aggressive.

Altered expression of the p53-regulated proteins, p21Waf1/Cip1, MDM2, and Bax in ultraviolet-irradiated human skin

The distribution of p21WAf1/CiP1, MDM2, and Bax/Bcl-2 proteins in ultraviolet (UV)-irradiated and nonirradiated human skin was examined immunohistochemically and compared with p53 protein levels. Sun-protected buttock skin from three volunteers was exposed to solar simulated irradiation, and biopsies were performed 0.5, 1, 2, 4, and 24 hours after irradiation as well as control unirradiated skin from the opposite buttock. A similar staining pattern was observed in each of the three volunteers. P53 protein was detectable in all skin samples examined. P21Waf1/CiP1 protein was visible in the nuclei of cells at 4 hours, and staining intensity increased at 24 hours. MDM2 protein expression was noted in isolated nuclei in the epidermis at 24 hours. Bax cytoplasmic staining was evident in the basal layer of the epidermis of all samples, and this staining appeared to increase in intensity in the 4- and 24-hour specimens. There was no Bcl-2 immunohistochemical staining in any sample. These results suggest that p53 and genes/proteins under the control of p53 are altered/ activated in normal human skin in response to UV exposure.