Actinomycin D-mediated sensitization of AIDS-Kaposi's sarcoma cells to Fas-mediated apoptosis: involvement of the mitochondrion-dependent pathway.

Fas engagement rapidly induces formation of the death-inducing signaling complex (DISC) that consists of Fas, FADD and pro-caspase-8. Activated caspase-8 at the DISC directly activates downstream caspases, resulting in induction of apoptosis of the independent mitochondria. In this study, we have obtained evidence demonstrating that Fas-mediated apoptosis in AIDS-KS cells takes place in a mitochondria-dependent manner.

p38MAP kinase is a negative regulator for ERK1/2-mediated growth of AIDS-associated Kaposi's sarcoma cells.

AIDS-associated Kaposi's sarcoma (KS) is a cytokine-mediated tumor, at least in the early stages of this disease; however, there is at present no definitive consensus regarding the exact role of intracellular signaling pathways involved in growth of KS cells. We found that KS cell growth factors oncostatin M, sIL-6R/IL-6, TNFalpha, and IL-1beta all activate ERK1/2, and selective blockage of this kinase by PD98059 resulted in a profound inhibition of the cytokine-induced KS cell growth. Concurrently with activation of ERK1/2, these growth factors phosphorylated and activated p38MAPK.

Oncostatin M (OM) promotes the growth of DU 145 human prostate cancer cells, but not PC-3 or LNCaP, through the signaling of the OM specific receptor.

Background: Oncostain M (OM) is a member of the interleukin-6 (IL-6) cytokine family and all members utilize gp130 as a common signal transducing receptor. Tyrosine phosphorylation of the transcription factor STAT3 plays an important role in IL-6 cytokine family-mediated reactions. OM signals are transduced through two different OM receptor complexes: a leukemia inhibitory factor (LIF)/OM receptor (a heterodimer of LIFR beta and gp130) and an OM specific receptor (a heterodimer of OMR beta and gp130).

Sensitization of AIDS-Kaposi's sarcoma cells to Apo-2 ligand-induced apoptosis by actinomycin D.

Kaposi's sarcoma (KS) is the most frequent malignancy associated with HIV infection (AIDS-KS), a complication that leads to high mortality and morbidity. AIDS-KS cells are resistant to killing by chemotherapeutic drugs/NK cells and Fas-induced apoptosis, suggesting that the acquisition of antiapoptotic characteristics by AIDS-KS cells may contribute to their prolonged survival. Apo-2 ligand (Apo-2L)/TNF-related apoptosis-inducing ligand, a new member of the TNF family, has been identified as an apoptosis-inducing molecule.