ASPO019 - The oncogenic microRNA miR-21 is upregulated in lymphatic malformation tissue and may drive endothelial migration and proliferation by targeting PDCD4
Saturday, April 30, 2022
10:30 AM – 11:05 AM CT
Location: Landmark C
Ravi Sun, BE1, Haihong Zhang, MD/PhD1, Stephanie Byrum, PhD2, June Wu, MD3, Carrie Shawber, PhD4, Gresham Richter, MD1, Jonathan Perkins, DO5, Graham Strub, MD/PhD1
Graham Strub, MD/PhD1;
1Otolaryngology, Univ. of Arkansas for Med. Sci., Little Rock, AR, 2Biochemistry and Molecular Biology, Univ. of Arkansas for Med. Sci., Little Rock, AR, 3Surgery, Columbia Univ. Med. Ctr., New York, NY, 4Obstetrics/Gynecology and Surgery, Columbia Univ. Med. Ctr., New York, NY, 5Otolaryngology, Univ. of Washington Sch. of Med., Seattle, WA.
Assistant Professor University of Arkansas for Medical Sciences/Arkansas Children's Hospital University of Arkansas for Medical Sciences/Arkansas Children's Hospital Little Rock, Arkansas
INTRODUCTION: MicroRNAs (miRNAs) are produced by all eukaryotic cells and function by attenuating protein synthesis by targeting messenger RNAs (mRNAs). Pediatric lymphatic malformations (LMs) contain endothelial cells (LM-ECs) which harbor mutations in PIK3CA; however, the function of miRNAs in LMs and LM-ECs is unknown. Here we demonstrate that miR-21, a known oncogenic miRNA, is highly expressed in LM tissue when compared to adjacent normal tissue. LM-ECs express miR-21, which targets the tumor suppressor PDCD4 (programmed cell death 4). PDCD4 binds to the translation initiation factor eIF4A and inhibits the transcription factor AP-1, leading to reduced proliferation and migration and increased apoptosis. We propose that inhibition of miR-21 in LMs with anti-miR-21 may be a novel molecular therapeutic modality in the treatment of LMs.
OBJECTIVE: To identify dysregulated miRNAs in LM-ECs which may be potential therapeutic targets.
METHODS: LM tissue/fluid and adjacent normal tissue was collected from 20 patients undergoing surgical treatment for LMs. LM-ECs were isolated using magnetic beads and cultured. RT-PCR analysis of 6 miRNAs known to function in lymphangiogenesis and migration/proliferation was performed and compared between LM tissue/normal tissue and LM-ECs/normal lymphatic endothelial cells (HDLECs). LM-ECs were transfected with antagomir or miR-mimic and expression was determined with RT-PCR, and the expression of the miR-21 target PDCD4 was determined with proteomics and western blot. LM-EC proliferation and migration assays in the presence or absence of antagomir/mimic were performed to determine the effect of miRNA manipulation.
RESULTS: miR-21 was upregulated in LM tissue when compared to surrounding normal tissue. LM-ECs are culturable and express miR-21, which is inhibited by transfection with anti-miR-21. LM-ECs proliferate and migrate at higher rates than HDLECs, and proliferation of LM-ECs appears attenuated in the presence of anti-miR-21. The tumor suppressor PDCD4 is downregulated in LM-ECs and is a direct target of miR-21.
CONCLUSION: The oncomir miR-21 is upregulated in LMs and may drive proliferation and migration of LM-ECs by targeting PDCD4, which is reversible with anti-miR-21. This represents a novel pathway for developing molecular-based treatments for LMs.