Although extensively studied, the exact nature of Kaposi's sarcoma (KS), the most common tumors in AIDS patients worldwide, is still controversial. KS is a highly vascularised tumor, apparently induced by HHV8 infection of vascular precursors, endothelial cells, circulating endothelial and/or haematopoietic progenitors. Cell lines derived from KS biopsies show similar characteristics: a mixture of mesenchymal and vascular markers. Given the growing interest in cancer stem cells as a new perspective in cancer treatment, we decided to isolate and characterize the potential stem sub-populations in KS cultures and to study whether the interaction of these cells with the microenvironment may influence their tumorigenicity.
Two KS cell lines (KS-IMM and SLK), cultured out of biopsy material from KS patients, were used to asses stemness capability of this tumor.
KS cells were karyotypically characterized, analyzed by functional genomics with Affymetrix arrays and then grown in specific serum-free stem cell medium. Cell proliferation assay showed an anchorage-independent growth capability of KS and SLK cell lines forming spheroid structures. With increasing passages, these KS-derived spheroids showed an increase in proliferation potential and sphere forming efficiency.
Surface expression markers on spheroids were evaluated through flow cytometry and compared to parental cell lines. Consistent increase in CD34 and CD326 and decrease in CD133 and CD144 were found in cells derived from KS-IMM spheroid compared to parental cells, while only ABCG2 is consistently decreased in SLK spheroids. Preliminary results suggest the existence of a KS subpopulation showing stemness features.
(C) 2012 Lippincott Williams & Wilkins, Inc.