THU575 The Canonical Wnt/β-catenin Pathway Is Not Involved In Estrogen-induced Skeletal Muscle Fibrosis In A Mouse Model Of Inguinal Hernia

Abstract

Abstract Disclosure: T. You: None. H. Zhao: None. T. Potluri: None. P. Yin: None. S.E. Bulun: None. Inguinal hernias affect up to 27% of elderly men, with approximately 800,000 inguinal hernia repair surgeries performed annually. While these procedures are often effective, a significant subset of hernias are refractory to treatment, resulting in high mortality, high recurrence, and chronic pain. Until recently, little research has been done examining the molecular mechanisms that drive hernia-associated lower abdominal wall weakening. Our lab previously created a transgenic mouse model expressing the human aromatase gene (Aromhum) and showed that male Aromhum mice produced high levels of estrogen in the lower abdominal muscle (LAM) tissue, leading to extensive LAM fibrosis, muscle atrophy, and hernia formation. Single-cell analysis of fibrotic LAM tissue in these mice showed high expression of estrogen receptor alpha (ERα) in LAM fibroblasts as well as upregulation of Wnt signaling pathways in these ERα-positive fibroblasts. The canonical Wnt/β-catenin signaling pathway has been implicated in fibroblast activation and fibrosis in multiple organs, including the lung, heart, and skin. Thus, we hypothesized that canonical Wnt/β-catenin signaling acts as a downstream mediator of ERα to cause LAM fibroblast activation, tissue fibrosis, and hernia. To test our hypothesis, we cultured primary ERα-positive LAM fibroblasts from Aromhum mice in the presence of estrogen with or without siRNA knockdown (KD) of β-catenin. However, KD of β-catenin under these conditions did not alter fibroblast proliferation as measured by EdU assay, nor did it alter expression of genes involved in fibroblast activation or extracellular matrix formation. Furthermore, administration of LGK974, a Wnt signaling inhibitor, in male Aromhum mice did not prevent hernia development, decrease hernia size, or decrease the extent of LAM fibrosis and muscle atrophy. Thus, we concluded that the canonical Wnt/β-catenin signaling pathway does not serve as a downstream mediator of estrogen-induced skeletal muscle fibrosis in our Aromhum mouse model of inguinal hernia. Further studies are needed to evaluate the role of Wnt/β-catenin signaling in other inguinal hernia models or in humans. Presentation Date: Thursday, June 15, 2023