vFLIP-regulated competing endogenous RNA (ceRNA) networks targeting lytic induction for KSHV-associated malignancies

Kaposi's sarcoma-associated herpesvirus (KSHV) causes life-long latent infection and malignancies, including KS commonly found in AIDS patients. Lytic replication can be induced to kill tumor cells harboring latent KSHV, through viral cytopathic effects and the subsequent antiviral immune responses. Viral FLICE-inhibitory protein (vFLIP), encoded by KSHV ORF K13, inhibits KSHV lytic reactivation, implying that the competing endogenous RNA (ceRNA) networks regulated by vFLIP can be modulated to induce the lytic reactivation of latent KSHV, a promising strategy for KSHV-associated malignancies. Here, we performed whole-transcriptome sequencing to reveal the global landscape of noncoding RNAs and messenger RNAs (mRNAs) in iSLK-RGB-BAC16 cells and iSLK-RGB-K13 mutant cells. It showed that vFLIP regulated 227 differentially expressed (DE) long non-coding RNAs (lncRNAs), 57 DE circular RNAs (circRNAs), 20 DE microRNAs (miRNAs), and 1371 DE mRNAs. Enrichment analysis verified that riboflavin metabolism was simultaneously enriched in DE genes related to miRNAs, lncRNAs, and circRNAs. The upregulated hsa-miR-378i and hsa-miR-3654, and downregulated miR-4467, miR-3163, miR-4451, and miR-4257 were significantly enriched in the ceRNA complex network, which contained 9 upregulated and 7 downregulated circRNAs, 5 upregulated and 85 downregulated lncRNAs, 5 upregulated and 35 downregulated mRNAs. Finally, we constructed and validated two vFLIP-regulated ceRNA networks: circRNA hsa_circ_0070049/hsa-miR-378i/SPEG/FOXQ1 and lncRNA AL031123.1/hsa-miR-378i/SPEG/FOXQ1. Taken together, the two ceRNA networks may mediate KSHV reactivation. These novel findings refreshed the present understanding of ceRNA network in KSHV lytic induction and provided potential therapeutic targets for KSHV-associated malignancies.