Date: Saturday, June 5, 2021
Session Time: 6:00pm-7:00pm
Presentation Time: 6:15pm-6:20pm
*Purpose: The platelet-derived growth factor and its receptor (PDGFRb) signaling pathway can be activated by epithelial mesenchymal transition which facilitates fibrosis. It is not known how PDGFRb is regulated following human transplant. We found that a tumor suppressor gene, liver kinase B1 (LKB1) knockdown induced epithelial mesenchymal transition in BEAS-2B airway epithelial cells. Furthermore, LKB1 was down regulated in lung transplant recipients diagnosed with chronic lung allograft dysfunction (CLAD). Since LKB1, a protein kinase 1, can regulate fibrosis, we investigated the role of LKB1 in the regulation of PDGFRb and, therefore, fibrosis leading to CLAD.
*Methods: To investigate the relationship between LKB1 and PDGFRb signaling pathways to define the mechanisms of development of CLAD following lung transplant. LKB1 was knocked down by siRNA in an airway epithelial cell line, BEAS-2B. The effect of LKB1 knockdown on gene regulation was measured by nanoSTRING technology. Differential gene expression analysis was performed to identify genes which were up-regulated or downregulated by LKB1 siRNA or control siRNA. Further downstream analysis was done by knocking down PDGFRb using siRNA and the effect was measured by western blot analysis. We also analyzed PDGFRb expression by real-time PCR in BOS biopsies (n=5) and stable biopsies (n=5).
*Results: In nanoSTRING platform, LKB1 knockdown significantly induced PDGFRb expression in BEAS-2B cells compared to the control siRNA (p=0.005). Densitometry analysis showed knocking down PDGFRb in BEAS-2B cells significantly inhibited NFκB (p=0.04), TNF-α (p=0.001), and phosphorylation of STAT3 (p=0.001). Kα1T (p=<0.05) and fibronectin (p=<0.05) expression were also significantly down-modulated following PDGFRb knockdown. We also analyzed the level of PDGFRb in human lung biopsies diagnosed as BOS and compared with biopsies from stable patients by real time PCR. We found PDGFRb expression was significantly increased in BOS biopsies when compared to stable biopsies (p=0.04).
*Conclusions: We identified a novel molecular mechanism in which LKB1 knockdown induces PDGFRb expression and regulates the NFκB-TNFα-STAT3 signaling pathways. Therefore, LKB1 downregulation, can play a significant role in the pathogenesis of CLAD after lung transplant.
To cite this abstract in AMA style:Rahman M, Lee J, Ravichandran R, Fleming T, Smith M, Bremner R, Mohanakumar T. Liver Kinase B1 Knockdown Induces Platelet-Derived Growth Factor Receptor B Expression in Human Airway Epithelial Cells: A Potential Mechanism for Development of Fibrosis Leading to Chronic Lung Allograft Dysfunction [abstract]. Am J Transplant. 2021; 21 (suppl 3). https://atcmeetingabstracts.com/abstract/liver-kinase-b1-knockdown-induces-platelet-derived-growth-factor-receptor-b-expression-in-human-airway-epithelial-cells-a-potential-mechanism-for-development-of-fibrosis-leading-to-chronic-lung-allog/. Accessed June 18, 2021.
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