Regulation of STAT5 phosphorylation and interaction with SHP1 by lnc-AC004893, a long non-coding RNA overexpressed in myeloproliferative neoplasms.

Objectives: Constitutive activation of Janus kinase 2 (JAK2)/signal transducer and activator of transcription (STAT) signaling pathway is central to the pathogenesis of myeloproliferative neoplasms (MPNs). Long noncoding RNAs (lncRNAs) regulate diverse biological processes. However, the role of lncRNAs in MPN pathogenesis is not well studied.
Methods: The expression of lnc-AC004893 in MPN patients was measured by quantitative real-time PCR (qRT-PCR). Gene-specific short hairpin RNAs (shRNAs) were designed to inhibit the expression of lnc-AC004893, and western blot was performed to explore the role of lnc-AC004893 via regulating the JAK2/STAT5 signaling pathway. Furthermore, co-IP was performed to determine the binding ability of lnc-AC004893 and STAT5 protein. Finally, the BaF3-JAK2V617F-transplanted mouse model was used to assess the biological role of lnc-ac004893 in vivo .
Results: We report that lnc-AC004893, a poorly conserved pseudogene-209, is substantially upregulated in MPN cells compared with normal controls (NCs). Knockdown of lnc-AC004893 by specific shRNAs suppressed cell proliferation and decreased colony formation. Furthermore, the knockdown of lnc-AC004893 reduced the expression of p-STAT5 but not total STAT5 in HEL and murine IL-3-dependent Ba/F3 cells, which present constitutive and inducible activation of JAK2/STAT5 signaling. In addition, inhibition of murine lnc-ac004893 attenuated BaF3-JAK2V617F-transplanted phenotypes and extended the overall survival. Mechanistically, knockdown of lnc-AC004893 enhanced the binding ability of STAT5 and protein tyrosine phosphatase SHP1. Furthermore, knockdown of lnc-AC004893 decreased STAT5-lnc-AC004893 interaction but not SHP1-lnc-AC004893 interaction.
Conclusion: Lnc-AC004893 regulates STAT5 phosphorylation by affecting the interaction of STAT5 and SHP1. Lnc-AC004893 might be a potential therapeutic target for MPN patients.