OBJECTIVE To investigate the effect and mechanism of gracillin from Reineckia carnea on autophagy in non- small cell lung cancer A549 cells. METHODS Using A549 cells as subjects， the effects of different concentrations of gracillin （0.25， 0.5， 1， 2， 4 μmol/L） on the proliferation of cells were detected by CCK-8 after being treated for different time （12， 24， 48 h）. Compared with the control group without medication， the effect of gracillin （2 μmol/L） on the formation of autophagosomes in cells was observed by transmission electron microscope after 24 h of exposure. The aggregation of GFP-LC3 on autophagosome membrane was detected by GFP-LC3 plasmid transfection after being treated with gracillin （0.25， 0.5， 1， 2 μmol/L） for 24 h. Quantitative real-time PCR and Western blot assay were used to detect the mRNA and protein expressions of family with sequence similarity 102 member A（FAM102A）， the expressions of autophagy-related proteins [p62， Beclin-1， microtubule-associated protein 1 light chain 3B （LC3B）]， and the expressions of phosphoinositide 3-kinase （PI3K）/protein kinase B （Akt） signaling pathway-related proteins in A549 cells after being treated with gracillin （0.25， 0.5， 1 and 2 μmol/L） for 24 h. RESULTS Gracillin significantly inhibited the proliferation of A549 cells in a concentration- and time-dependent manner. The IC50 was 2.55 μmol/L at 24 h. After 24 h of gracillin treatment， autophagosomes with bilayer membrane structure were found in the cell cytoplasm， and GFP-LC3 green fluorescent spots on autophagosome membrane were obvious， representing an increasing trend as drug concentration. Compared with the control group， mRNA and protein expressions of FAM102A （0.5， 1， 2 μmol/L groups）， protein expression of Beclin-1 （1， 2 μmol/L groups） and LC3B-Ⅱ/LC3B-Ⅰ ratio （2 μmol/L group） were significantly increased in different concentrations of gracillin groups， while the protein expression of p62 （1， 2 μmol/L groups）， and the protein phosphorylations of Akt （1， 2 μmol/L groups） and PI3K （2 μmol/L group） were all decreased significantly （P＜0.05 or P＜0.01）. CONCLUSIONS Gracillin can promote excessive autophagy in A549 cells by up-regulating mRNA and protein expressions of FAM102A and inhibiting PI3K/Akt signaling pathway， thus inhibiting cell proliferation.

Regeneration and repair are two different forms of human skin wound healing. Adult wounds can form scars through fibrous repair, while fetal skin wounds heal well without scars, and can even regenerate, completely restoring the structure and function of the original tissue. Understanding the different mechanisms of fetal wound healing is essential for developing new scar prevention therapies. In this review, the author summarized the recent research progress in scarless healing of fetal wounds, especially new discoveries in skin cells such as fibroblasts, mesenchymal stem cells and their exosomes and gene expression, immune cells and inflammation. It will be beneficial to develop new method to promote the development of adult wounds to scarless healing, and to provide new ideas for scar treatment and skin regeneration and repair by learning from the mechanism of fetal wound healing.

Regeneration and repair are two different forms of human skin wound healing. Adult wounds can form scars through fibrous repair, while fetal skin wounds heal well without scars, and can even regenerate, completely restoring the structure and function of the original tissue. Understanding the different mechanisms of fetal wound healing is essential for developing new scar prevention therapies. In this review, the author summarized the recent research progress in scarless healing of fetal wounds, especially new discoveries in skin cells such as fibroblasts, mesenchymal stem cells and their exosomes and gene expression, immune cells and inflammation. It will be beneficial to develop new method to promote the development of adult wounds to scarless healing, and to provide new ideas for scar treatment and skin regeneration and repair by learning from the mechanism of fetal wound healing.