Repurposing cytarabine for treating primary effusion lymphoma by targeting KSHV latent and lytic replications

Oncogenic Kaposis sarcoma-associated herpesvirus (KSHV) is etiologically linked to primary effusion lymphoma (PEL), an aggressive and non-treatable malignancy commonly found in AIDS patients. In this study, we performed a high throughput screening of 3,731 characterized compounds, and identified cytarabine approved by FDA for treating numerous types of cancer as a potent inhibitor of KSHV-induced PEL. We showed the high efficacy of cytarabine in the growth inhibition of various PEL cells by inducing cell cycle arrest and apoptosis. Cytarabine inhibited host DNA and RNA syntheses and therefore induced cellular cytotoxicity. Furthermore, cytarabine inhibited viral DNA and RNA syntheses and induced the the rapid degradation of KSHV major latent protein LANA, leading to the suppression of KSHV latent replication. Importantly, cytarabine effectively inhibited active KSHV replication and virion production in PEL cells. Finally, cytarabine treatments not only effectively inhibited the initiation and progression of PEL tumors, but also induced regression of grown PEL tumors in a xenograft mouse model. Together, our study has identified cytarabine as novel therapeutic agent for treating PEL as well as eliminating KSHV persistent infection.\n\nImportancePrimary effusion lymphoma is an aggressive malignancy caused by Kaposis sarcoma-associated herpesvirus. The outcome of primary effusion lymphoma is dismal without specific treatment. Through a high throughput screening of characterized compounds, we identified a FDA-approved compound cytarabine as a potent inhibitor of primary effusion lymphoma. We showed that cytarabine induced regression of PEL tumors in a xenograft mouse model. Cytarabine inhibited host and viral DNA and RNA syntheses, resulting in the induction of cytotoxicity. Of interest, cytarabine induced the degradation of KSHV major latent protein LANA, hence suppressing KSHV latent replication, which is required for PEL survival. Furthermore, cytarabine inhibited KSHV lytic replication program, preventing virion production. Our findings identified cytarabine as novel therapeutic agent for treating PEL as well as for eliminating KSHV persistent infection. Since cytarabine is already approved by the FDA, it might be an ideal candidate for repurposing for PEL therapy and for further evaluation in advanced clinical trials.