MALAT1 Knockdown Inhibits the Proliferation, Migration, and Collagen Deposition of Human Hypertrophic Scar Fibroblasts Via Targeting MiR-29a-3p/Smurf2 Axis

Purpose: Hypertrophic scarring (HS) is commonly described as an abnormal post-traumatic tissue repair characterized by excessive hypercellularity and extracellular matrix (ECM) deposition. Mounting evidence suggests that MALAT1 is maladjusted in many fibrotic diseases, but its contribution to HS progression remains poorly understood. Hence, we sought to elucidate the fundamental role of MALAT1 in HS.

Methods: The expression of MALAT1, miR-29a-3p, and Smurf2 in skin tissues and fibroblasts was assessed by RT-qPCR and Western blotting. Furthermore, lentiviruses, RNAi, or plasmids were utilized to transfect hypertrophic scar fibroblasts (HSFs) for gene overexpression or downregulation. The biological behaviors of HSFs were quantified by the CCK-8 assay, wound healing assay, transwell assay, and flow cytometry. Mechanistically, bioinformatics analysis, dual-luciferase reporter assays, and rescue experiments were performed to verify the relationship between miR-29a-3p and MALAT1 or Smurf2.

Results: Our data indicate that MALAT1, Smurf2 were overexpressed while miR-29a-3p was suppressed in HS tissues and fibroblasts. Downregulation of MALAT1 may lead to decreased proliferation, migration, and invasion of fibroblasts, accompanied by enhanced apoptosis, reduced TGF-β signal transduction, and ECM accumulation in HSFs, by enhancing miR-29a-3p and suppressing Smurf2 expression. Mechanistically, MALAT1 acted as a sponge for miR-29a-3p, while miR-29a-3p directly targeted Smurf2. More importantly, rescue experiments suggested that MALAT1 downregulation induced impact on the proliferation, migration, and invasion of HSFs could be partially overturned through miR-29a-3p knockdown or Smurf2 overexpression.

Conclusion: MALAT1 knockdown inhibits the proliferation, migration, invasion, and collagen deposition of HSFs via targeting the miR-29a-3p/Smurf2 axis, which may reveal a promising therapeutic exploitable vulnerability to HS.