Kaposi's sarcoma and human chorionic gonadotropin: mechanisms, moieties and mysteries

Kaposi's Sarcoma (KS) is a highly angiogenic neoplasm associated with infection by the human gamma-herpesvirus, HHV-8 or Kaposi's sarcoma herpes virus (KSHV). When in 1872 the Hungarian scientist Moritz Kaposi described the sarcoma, which was later named after him, he was dealing with a rare dermatologic disease. Today, KS is a more common pathology due to its high incidence in AIDS, in immuno-suppressed transplantation patients and, in its endemic form, in Africa. The introduction of highly active antiretroviral therapy (HAART) has led to a drastic reduction of KS incidence in HIV-infected patients, but in some cases KS resists the treatment. KS is more common in men than in women. The observation of spontaneous remissions during pregnancy stimulated investigations into the potential anti-KS activity of the pregnancy hormone human chorionic gonadotropin (hCG). The variable effect in clinical trials using urinary preparations of the hormone (u-hCG) has led to the hypothesis that contaminating moieties present in these preparations may account for the anti-KS effect observed in vitro. While the discrepancy between laboratory tests and clinical trials remains a mystery, little is known about potential anti-KS mechanisms of the hormone itself and/or other active moieties present in u-hCG.