PubMed · 1616963
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G W Middleton, R K Lau. AIDS lymphomas.. https://doi.org/10.1177/095646249200300304
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Mithramycin is a DNA-binding antibiotic that has been reported to selectively affect c-myc expression [Snyder, R. C. et al., (1991) Biochemistry 30, 4290-4297]. We used in vitro transcription to investigate the specificity of mithramycin action. We found that mithramycin inhibited transcription from the human c-myc P1 and P2 promoters, as well as from a minimal adenovirus-2 major late promoter, with equal efficiencies. Mithramycin also inhibited transcription elongation by creating kinetic blockades to the passage of RNA polymerase II. These data suggest that mithramycin may inhibit transcription non-specifically by affecting general processes such as transcription elongation.
The data presented here indicate that the pathogenesis of AIDS-NHL is variably associated with multiple genetic alterations including monoclonal EBV infection, oncogene activation (c-myc, N-, Ki-ras) and tumor suppressor gene (p53) inactivation. Up to three (3 cases) or four (1 case) different lesions have been observed in the same tumor. The distribution of these lesions among the various histotypes is heterogeneous, although some preferential associations have been found either between lesion and histotype or between lesions. The most notable case involves p53 mutations/loss that is exclusively associated with the SNCC lymphoma subtype. Since alterations of the c-myc gene occur at very high frequency in this same histotype it is possible that both lesions may be required for the pathogenesis of the BL phenotype. The consistent negativity of p53 lesions in other NHLs associated or non associated with HIV infection (18) reinforces this hypothesis. Finally, we note that the frequency of p53 mutations is significantly higher in AIDS-BL than in non HIV-related BL (18), although the significancy of this difference remains to be assessed. This study confirms the relatively low frequency of EBV infection in systemic AIDS-NHL in general, but reinforces the notion that EBV may be required for the pathogenesis of AIDS-LC-IBP, as recently suggested by the high frequency of EBV positivity in primary CNS AIDS-NHL which are mostly represented by LC-IBP (2). Conversely, the low frequency of EBV sequences in the AIDS-SNCC lymphomas appears similar to that observed in sBL. Only in a small minority of cases were ras oncogene mutations found, mostly associated with the BL type.(ABSTRACT TRUNCATED AT 250 WORDS)
Transplant recipients develop numerous benign and malignant cutaneous and mucosal lesions in which histological signs of human papillomavirus (HPV) infection are observed. To investigate the role of HPV and c-myc and c-Ha-ras cellular oncogenes' activation in transplanted patients lesions, we used in situ hybridization with biotinylated probes and Southern blot to detect HPV and oncogenes DNA. We analyzed 36 lesions from grafted patients: 11 common warts, 10 actinic keratoses, 13 squamous cell carcinomas and 2 anogenital papillomas. With in situ hybridization, HPV DNA was detected in 14/36 lesions, 10 of which contained several HPV types. Benign and potentially oncogenic HPV types were detected in warts as well as in squamous cell carcinomas. The Southern blot technique confirmed the distribution of HPV types. Group specific viral antigen was detected in 12 lesions, mainly warts. C-Ha-ras oncogene was amplified in 13 lesions and c-myc oncogene in 10 lesions, 9 of which showed both oncogene amplification. The results obtained with in situ hybridization for c-myc gene amplification were confirmed with the Southern blot technique in 11/14 cases. Ras and/or myc amplification was more frequent in squamous cell carcinomas and anogenital papillomas than in warts and actinic keratoses. The amplification was not always linked to the presence of HPV DNA; however, it was more frequent in lesions infected by potentially oncogenic HPV types than in lesions containing only benign HPV types. Myc and p21 oncoproteins were respectively localized in the nucleus and on the membrane of epithelial cells by immunofluorescence. Most lesions showed a good concordance between the detection of oncogene DNA and proteins. Our results suggest than c-Ha-ras and c-myc cellular oncogenes' activation and HPV infection could play a role in the cancerization of cutaneous lesions from transplant recipients.