Molecular mechanisms of gallic acid-induced growth inhibition, apoptosis, and necrosis in hypertrophic scar fibroblasts

To explore the effect and molecular mechanism of gallic acid (GA) on the cytostatic and cytotoxicity of hypertrophic scar fibroblasts (HSFs).HSFs were treated with a serial dose of GA for indicated time. The cytostatic and cytotoxicity of GA were evaluated by microscopy, trypan blue exclusion assay and LDH releasing. The mechanisms of GA-induced cytostatic were examined by cell cycle distribution assay and the expression of cell cycle-relative protein. GA-elicited apoptosis were verified by TUNEL assay, mitochondria membrane potential, caspase activity and the expression of apoptosis-relative protein. GA-induced necrosis was confirmed by lysosome rupture using acridine orange stain. Various blockers, including intracellular calcium chelator; BAPTA-AM, IP3R blocker; 2-APB, calpain inhibitor, ALLM and ALLN were used to address the signaling cascade in GA-induced HSF necrosis.GA-induced growth inhibition, apoptosis, and necrosis in HSFs depend on increasing dose. HSFs treated with GA at non-cytotoxic concentrations (50 to 75μM) significant increased both the S- and G2/M-phase HSFs population, and this event was accompanied with down-regulation of cyclin A, cyclin B, CDK1 and CDK2. Incubation of HSFs with 100-150μM of GA induced apoptosis through Bcl2/Bax-mitochondrial-dependent pathway. While the concentrations up to 200μM of GA that elicited necrosis via a calcium/calpain I/lysosome rupture signaling axis. Interestingly, GA at 200μM did not harm to keratinocyte.These results revealed that GA might have the potential to be developed as a treatment for patients with hypertrophic scar.