Promoting effect of ultra-low dose DMSO on fibroblast proliferation and its underlying mechanism

Abstract Objective To investigate the effect of ultra-low dose of dimethyl sulfoxide (DMSO) on the proliferation of skin fibroblasts and to explore its underlying molecular mechanism. Methods MTT assay was used to determine the effect of different concentrations of DMSO on the proliferation of skin fibroblasts. Pull-down assay with 7-methylguanosine triphosphate (7mGTP) and Western blotting was employed to detect the changes in eukaryotic initiation factor 4E (eIF4E) and its binding protein, 4E-BP1, and eukaryotic translation initiation factor 4G (eIF4G). After intervention with mTOR inhibitor, rapamycin, the alterations in the expression and phosphorylation levels of proteins within the PI3K/Akt/mTOR signaling pathway were examined with Western blotting. Results Treatment with 11.0 nmol/L DMSO significantly increased both the cell proliferation rate (P<0.05) and the activity of the cap-dependent translation initiation luciferase reporter gene (P<0.05). Results from 7mGTP pull-down assay and Western blotting demonstrated that 11.0 nmol/L DMSO notably inhibited the binding of 4E-BP1 to eIF4E (P<0.05) while promoting the binding of eIF4G to eIF4E (P<0.05). Compared with the control group, the phosphorylation levels of p-Akt (S473), p-mTOR (S2448), p-4E-BP1 (T37/46), and p-p70S6K (T421/424) were upregulated (P<0.05); the total protein expressions of Akt, mTOR, p70S6K, S6, eIF4E, and 4E-BP1 were increased to varying degrees(P<0.05). In the RAPA intervention group, the phosphorylation levels of p-Akt (S473), p-mTOR (S2448), p-p70S6K (T421/424), and p-S6 (S235/236) were significantly lower than those in the control group (P<0.05). When comparing the RA + DMSO group with the RA group, the phosphorylation levels of all aforementioned proteins were significantly upregulated except for p-eIF4E (S209) (P<0.05). For protein expression analysis: relative to the control group, the DMSO group exhibited increased expressions of Akt, p70S6K, and mTOR (P<0.05) except for 4E-BP1; the RAPA group showed significant downregulation in all these proteins (P<0.05); compared with the RA group, the RA + DMSO group displayed significantly higher expressions of all these proteins except for p70S6K (P<0.05). Conclusion Ultra-low dose of DMSO (11.0 nmol/L) promotes the proliferation of mouse skin fibroblasts by mediating the PI3K/Akt/mTOR signaling pathway, thereby potentially accelerating wound healing.