New SMAD2 phosphorylation inhibitors screening and application for restraining fibroblast activation

Background and Purpose: Tissue fibrosis remains a significant clinical challenge due to the lack of specific, effective treatments. Current therapeutic strategies targeting TGF-β, a key driver of fibrosis, have shown limited efficacy and are often associated with severe side effects. This highlights the urgent need for novel therapeutic approaches to effectively modulate the TGF-β signaling and prevent fibrosis progression. Experimental Approach: We screened a lead compound library to interfere with SMAD2 phosphorylation, based on the structure and phosphorylation site of SMAD2. Surface plasmon resonance was used to determine the binding affinities of the compounds to SMAD2. LX-2 cell line was utilized to examine compounds’ effect on TGF-β signaling. SMAD2 phosphorylation was tested to verify the inhibition effect of candidate compounds. The mRNA expression of COL1A1 and ACTA2 was detected to evaluate the role of SMAD2. The protein level of COLLAGEN I and α-SMA were confirmed by Enzyme-linked immuno sorbent assay and Immunofluorescence. Key Results: Eight compounds were identified as targeting the phosphorylation of SMAD2. Of these, two compounds 6253-0511 and 8005-4391 were confirmed to be highly effective in inhibiting TGF-β-induced increases in COLLAGEN I and α-SMA levels in hepatic stellate cells, thus blocking the fibrotic process. Conclusion and Implications: In this study, we addressed the modulate TGF-β signaling pathway gap by focusing on SMAD2, a critical downstream mediator of TGF-β signaling. Two compounds were confirmed to effectively inhibit the fibrotic process, providing new insight into the therapeutic potential of targeting SMAD2 phosphorylation as a strategy for combating fibrosis.