[HTML][HTML] Sphingosine kinase-2 maintains viral latency and survival for KSHV-infected endothelial cells

L Dai, K Plaisance-Bonstaff, C Voelkel-Johnson… - PloS one, 2014 - journals.plos.org
PloS one, 2014journals.plos.org
Phosphorylation of sphingosine by sphingosine kinases (SphK1 and SphK2) generates
sphingosine-1-phosphate (S1P), a bioactive sphingolipid which promotes cancer cell
survival and tumor progression in vivo. We have recently reported that targeting SphK2
induces apoptosis for human primary effusion lymphoma (PEL) cell lines infected by the
Kaposi's sarcoma-associated herpesvirus (KSHV), and this occurs in part through inhibition
of canonical NF-κB activation. In contrast, pharmacologic inhibition of SphK2 has minimal …
Phosphorylation of sphingosine by sphingosine kinases (SphK1 and SphK2) generates sphingosine-1-phosphate (S1P), a bioactive sphingolipid which promotes cancer cell survival and tumor progression in vivo. We have recently reported that targeting SphK2 induces apoptosis for human primary effusion lymphoma (PEL) cell lines infected by the Kaposi’s sarcoma-associated herpesvirus (KSHV), and this occurs in part through inhibition of canonical NF-κB activation. In contrast, pharmacologic inhibition of SphK2 has minimal impact for uninfected B-cell lines or circulating human B cells from healthy donors. Therefore, we designed additional studies employing primary human endothelial cells to explore mechanisms responsible for the selective death observed for KSHV-infected cells during SphK2 targeting. Using RNA interference and a clinically relevant pharmacologic approach, we have found that targeting SphK2 induces apoptosis selectively for KSHV-infected endothelial cells through induction of viral lytic gene expression. Moreover, this effect occurs through repression of KSHV-microRNAs regulating viral latency and signal transduction, including miR-K12-1 which targets IκBα to facilitate activation of NF-κB, and ectopic expression of miR-K12-1 restores NF-κB activation and viability for KSHV-infected endothelial cells during SphK2 inhibition. These data illuminate a novel survival mechanism and potential therapeutic target for KSHV-infected endothelial cells: SphK2-associated maintenance of viral latency.
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