SIRT6 Inhibits the Proliferation and Collagen Synthesis of Keloid Fibroblasts through MAPK/ERK Pathway.

ABSTRACT

BACKGROUND: Keloid, a fibroproliferative disorder, significantly impacts patients' quality of life, yet effective therapies remain elusive. This study explored the role of silent information regulator 6 (SIRT6) in modulating the proliferation, invasion, and collagen synthesis of keloid fibroblasts. METHODS: Keloid and normal skin specimens were collected, and fibroblasts were isolated from the keloid tissue. SIRT6 recombinant adenovirus (Ad) was constructed to infect keloid fibroblasts to overexpress SIRT6. This study entails three groups Control group, adenovirus-Negative Control (Ad-NC) group, and Ad-SIRT6 group. SIRT6 protein and mRNA levels were measured via Western blotting and Quantitative reverse transcription polymerase chain reaction (qRT-PCR), respectively. Cell viability was determined using 5-ethynyl-2'-deoxyuridine (EdU) assay. Flow cytometry was exploited to measure cell apoptosis. To investigate cell migration, wound healing assay and Transwell assay were employed. Western blotting was also utilized to study the expression levels of apoptotic proteins, collagen deposition-related proteins, and Mitogen-Activated Protein Kinases (MAPK)/extracellular regulated protein kinases (ERK) pathway-related proteins. RESULTS: Compared to the control and Ad-NC groups, the Ad-SIRT6 group exhibited significantly elevated SIRT6 level; diminished cell proliferation, migration and invasion; reduced protein levels of α-smooth muscle actin (α-SMA), collagen I, collagen III, phospho SMAD Family Member 3 (p-Smad3), transforming growth factor-ß 1 (TGF-ß1), and MAPK/ERK pathway proteins (phospho extracellular signal-regulated protein kinase 1/2 (p-ERK1/2), phospho MAP kinase-ERK kinase (p-MEK) and phospho-c-Raf (p-c-Raf)). Treatment with epidermal growth factor (EGF), an MAPK/ERK pathway agonists, reversed the inhibitory effect of SIRT6 on cell activity and inhibited apoptosis in keloid fibroblasts. CONCLUSION: SIRT6 overexpression in keloid fibroblasts attenuates proliferation, invasion, and collagen synthesis, while fostering apoptosis, likely through the suppression of MAPK/ERK pathway activity. This suggests a potential therapeutic target for keloid treatment.