Upregulation of RAF and RalGDS gene expression by TGF-β in systemic sclerosis dermal fibroblasts: a controlled in vitro study.

INTRODUCTION

Systemic sclerosis is an autoimmune rheumatic disorder characterized by uncontrolled fibroblast activation, skin thickening, and fibrosis. Activated Ras and ERK signaling significantly affect fibrosis and EMT upon TGF-β treatment. RalGDS may play an important role in inflammatory and oncogenic processes. This study investigates the expression of RAF and RalGDS genes in SSc patients compared to healthy individuals before and after treatment with TGF-β.

METHODS

This research included 20 patients with systemic sclerosis and 18 healthy controls matched for age and sex. Skin biopsies were collected, and fibroblasts were grown and expanded. The identity of fibroblasts was confirmed using immunofluorescence labeling. Fibroblasts were subjected to TGF-β1 treatment, and the expression levels of A-RAF, B-RAF, C-RAF, and RalGDS genes were assessed via real-time PCR.

RESULTS

Gene expression analysis revealed no significant baseline changes in RAF and RalGDS between groups; however, TGF-β therapy dramatically raised both genes in SSc cells relative to controls. A positive association was identified between the expression levels of the RAF and RalGDS genes.

CONCLUSIONS

This study investigated A-RAF, B-RAF, C-RAF, and RalGDS gene expression in fibroblasts from SSc patients and healthy controls, focusing on their response to TGF-β treatment. While baseline expression levels were similar between groups, TGF-β significantly upregulated these genes in SSc fibroblasts more than in controls. This suggests that TGF-β signaling may contribute to the dysregulation of RAF and RalGDS pathways in SSc, highlighting their potential as biomarkers and therapeutic targets for the disease. Key Points • No significant difference in gene expression levels between SSc and healthy fibroblasts. • SSc and healthy fibroblasts exhibit upregulated RAF and RalGDS expression at the mRNA level in response to TGF-β treatment. • Positive correlation between the expression levels of A-RAF and B-RAF, B-RAF and C-RAF, and finally between C-RAF and RalGDS genes.