Abstract
Erdheim–Chester disease (ECD) is characterized by excessive production and accumulation of histiocytes within multiple tissues and organs. ECD patients harbor recurrent mutations of genes associated with the RAS/RAF/MEK/ERK signaling pathway, particularly, the BRAFV600E mutation. Following our previous finding that miR-15a-5p is the most prominently downregulated microRNA in ECD patients compared to healthy individuals, we elucidated its role in ECD pathogenesis. Bioinformatics analysis followed by a luciferase assay showed that chemokine ligand 10 (CXCL10) is a target gene regulated by miRNA-15a-5p. This was confirmed in 24/34 ECD patients that had low expression of miR-15a-5p concurrent with upregulated CXCL10. Overexpression of miR-15a-5p in cell lines harboring BRAF or RAS mutations (Ba/F3, KG-1a and OCI-AML3) resulted in CXCL10 downregulation, followed by LIN28a and p-ERK signaling downregulation and let-7 family upregulation. Overexpression of miR-15a-5p inhibited cell growth and induced apoptosis by decreasing Bcl-2 and Bcl-xl levels. Analysis of sequential samples from 7 ECD patients treated with MAPK inhibitors (vemurafenib/cobimetinib) for 4 months showed miR-15a-5p upregulation and CXCL10 downregulation. Our findings suggest that miR-15a-5p is a tumor suppressor in ECD through the CXCL10-ERK-LIN28a-let7 axis, highlighting another layer of post-transcriptional regulation in this disease. Upregulation of miR-15a-5p in ECD patients may have a potential therapeutic role.
Highlights
INTRODUCTION ErdheimChester disease (ECD) is a rare histiocytic disorder with diverse clinical manifestations, ranging from indolent, localized presentations to a life-threatening, multi-system disease [1]
We have recently showed that the miRNA profile of Erdheim–Chester disease (ECD) patients differs from that of healthy controls [10]
Our results revealed that ECD patients have elevated levels of CXCL10, associated with downregulation of miR15a-5p
Summary
Bioinformatics analysis followed by a luciferase assay showed that chemokine ligand 10 (CXCL10) is a target gene regulated by miRNA-15a-5p This was confirmed in 24/34 ECD patients that had low expression of miR-15a-5p concurrent with upregulated CXCL10. 15a-5p resulted in CXCL10 downregulation, followed by downregulation of the oncogene LIN28a and p-ERK signaling, leading to upregulation of the tumor suppressor let-7 family miRNAs. miR-15a-5p inhibited cell growth and induced apoptosis. Analysis of sequential samples from 7 ECD patients treated with MAPK inhibitors (vemurafenib/cobimetinib) for 4 months resulted in upregulation of miR-15a-5p and downregulation of CXCL10. The diluted PreAmp product was used as a template for real-time PCR analysis as described above These findings show that miR-15a-5p may function as a tumor suppressor in ECD patients through the CXCL10-ERK-LIN28a-let axis, highlighting an additional layer of post-transcriptional regulation in this disease. We used a Discovery Ultra instrument with a multimer/DAB detection system (Ventana Medical Systems Inc., Tucson, AZ, USA) with appropriate negative and positive controls using the following antibodies targeting human tissue: anti-CXCL10 (IP-10) (clone JA10-82; Host Species: Rabbit mAb; dilution: 1:200; Thermo Fisher Scientific, Waltham, MA, USA) and phospho-
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
