Endemic and atypical Kaposi's sarcoma in Africa--histopathological aspects

An Sp1 response element in the Kaposi's sarcoma-associated herpesvirus open reading frame 50 promoter mediates lytic cycle induction by butyrate

Kaposi's sarcoma-associated herpesvirus (KSHV) can be driven into the lytic cycle in vitro by phorbol esters and sodium butyrate. This report begins to analyze the process by which butyrate activates the promoter of KSHV open reading frame 50 (ORF50), the key viral regulator of the KSHV latency to lytic cycle switch. A short fragment of the promoter, 134 nucleotides upstream of the translational start of ORF50, retained basal uninduced activity and conferred maximal responsiveness to sodium butyrate. The butyrate response element was mapped to a consensus Sp1-binding site. By means of electrophoretic mobility shift assays, both Sp1 and Sp3 were shown to form complexes in vitro with the ORF50 promoter at the Sp1 site. Butyrate induced the formation of a group of novel complexes, including several Sp3-containing complexes, one Sp1-containing complex, and several other complexes that were not identified with antibodies to Sp1 or Sp3. Formation of all butyrate-induced DNA-protein complexes was mediated by the consensus Sp1 site. In insect and mammalian cell lines, Sp1 significantly activated the ORF50 promoter linked to luciferase. Chromatin immunoprecipitation experiments in a PEL cell line showed that butyrate induced Sp1, CBP, and p300 binding to the ORF50 promoter in vivo in an on-off manner. The results suggest that induction of the KSHV lytic cycle by butyrate is mediated through interactions at the Sp1/Sp3 site located 103 to 112 nucleotides upstream of the translational initiation of ORF50 presumably by enhancing the binding of Sp1 to this site.

Epidemiology of AIDS-related malignancies an international perspective

Patients with HIV infection are at increased risk for developing Kaposi's sarcoma, non-Hodgkin's lymphoma, and several other cancers. The relative risks for the most common epithelial cancers in the general population--lung, breast, colon/rectum, stomach, liver, and prostate--are not increased substantially in people with AIDS, however. Accumulating data suggest that HIV-infected patients also are at increased risk for developing Hodgkin's lymphoma, cervical carcinoma in situ (CIS), other anogenital neoplasms (invasive cancer and CIS), leiomyosarcoma, and conjunctival squamous cell carcinoma. There is inconclusive evidence, however, with regard to HIV infection being associated with invasive cervical cancer, testicular seminoma, or hepatocellular carcinoma. Notably, other viral infections have been implicated in the etiology of many of these conditions. The introduction of highly active antiretroviral therapy (HAART) has decreased the incidence of AIDS-associated cancers in Western countries, but less than 1% of AIDS patients are receiving HAART in the HIV epicenter of sub-Saharan Africa. Further therapeutic advances that extend survival with HIV infection with varying reconstitution of immune competence may lead to additional alterations in cancer risk.

Kaposi's sarcoma: advances and perspectives

Kaposi's sarcoma (KS) is an unusual neoplasm that has proved to be an enigma in many ways since its original description by Kaposi in 1872. Its epidemiology has stimulated tremendous interest, amplified markedly in 1981 when it became known as an original defining part of the complex of immune disorders now known as AIDS. The cell of origin, etiology, and therapy for both AIDS-associated and AIDS-unassociated KS continue as matters of intense investigation. In fact, whether it is a reactive hyperplasia or a true malignancy is still a matter of debate, as is the concept of multicentricity versus metastases. Epidemiologic studies suggest that a separate agent apart from HIV-1 may cause KS. A newly postulated KS-associated herpes virus may be linked. The role of the HIV-1 tat gene product, basic fibroblast growth factor, scatter factor, oncostatin M, and other factors that regulate the growth of KS cells are discussed, as well as therapeutic options.

The spectrum of African Kaposi's sarcoma: is it consequential upon diverse immunological responses?

Kaposi's sarcoma (KS) is a complex, multicellular growth, the pathogenesis of which remains unclear. Endemic African Kaposi's Sarcoma (KS) is characterized by its epidemiological peculiarities, protean clinical manifestations and an unpredictable natural history. A wide spectrum of clinical manifestations occurs, although the reasons for the heterogeneity remain unclear. Clinical observations in the presentation of human immunodeficiency virus (HIV)-associated epidemic African KS show a considerable overlap with endemic African KS obscuring the conventional binomial concept of African KS which was developed in light of the HIV epidemic. It is probable that once the KS lesions are expressed clinically, the subsequent spectrum and behaviour of all forms of African KS are consequential upon a complex interplay between the nature of the host cell-mediated immune responses and the putative aetiological factor(s).

Radiation therapy in endemic (African) Kaposi's sarcoma

PURPOSE

Evaluating the role of radiation therapy in the treatment of the endemic, African variant of Kaposi's sarcoma. A retrospective analysis.

METHODS AND MATERIALS

Between 1978 and 1990, 28 symptomatic African patients with the African Human Immunodeficiency Virus negative type of Kaposi's sarcoma were referred to the Johannesburg General Hospital. Following staging, all patients were treated with radiation therapy. Doses ranged between 8-10 Gy (single fraction) or 14-24 Gy fractionated over 1-3 weeks.

RESULTS

Complete and partial regression of cutaneous lesions was achieved in 9 (32%) and 15 (54%) patients, retrospectively. A complete/near-complete alleviation of symptoms was achieved in all patients. Response rate and duration of response was not influenced by age, radiation modality or schedule. Side effects were minimal.

CONCLUSION

Our study emphasizes the high radiosensitivity of the endemic, African type of Kaposi's sarcoma, indicating its usefulness as the treatment of choice for this disease.