Objective:To investigate the role of epidermal growth factor receptor (EGFR)in the regulation of B[a]P-induced silent information regulator 1 (SIRT1 ) activation in the human bronchial epithelial cells (BEAS-2B),and to clarify the relationship between EGFR/SIRT1 signal transduction pathway and the occurrence and development lung cancer.Methods:The prediction analysis of transcriptional factor binding sites of SIRT1 was performed by MOTIF SearchTM software.The primary cultivated BEAS-2B cells were divided into control group (without B[a]P exposure)and B[a]P groups (the cells were exposed to B[a]P for 6,12,24,48 h).RT-PCR and Western blotting method were carried out to detect the EGFR mRNA and protein expression levels.The BEAS-2B cells transfected with SIRT1 promotor luciferase reporter gene plasmid were treated with human epidermal growth factor (hEGF)and Genistein (tyrosine protein kinase inhibitor)for 24 h,the morphology of BEAS-2B cells was observed by inverted microscope, and luciferase reporter assay was used to test the SIRT1 transcriptional activity.The human lung tissue biopsies were acquired and the immunohistochemical analysis was used to determine the EGFR protein expression level.Results:The transcriptional factor binding sites of SIRT1 contained EGF, 2Fe-2S and vWF.Compared with control group,the expression levels of EGFR mRNA in B [a]P groups were increased in a time-dependent manner,and reached the peak at 12 h (P < 0.05);the EGFR protein expression levels were also increased (P <0.05).The SIRT1 luciferase activity in hEGF group was increased compared with control group (P <0.05);when hEGF and B[a]P worked together,the SIRT1 luciferase activity was increased even further (P <0.001). The cells showed arrangement and morphologic changes gradually when the B[a]P concentration was above 30 μmol · L-1. Genistein (30 μmol · L-1 )inhibited the increase of SIRT1 luciferase activity induced by B [a]P ,and there was significant difference compared with control group (P <0.05).The immunohistochemistry results showed that EGFR expression level in lung cancer tissue was higher than that in normal lung tissue (P < 0.001).Conclusion:EGFR can regulate the B [a]P-induced SIRT1 expression in BEAS-2B cells,and to cause lung chronic inflammation;EGFR/SIRT1 signal transduction pathway may play a role in the occurrence and development of lung cancer.

ObjectiveTo compare the effects of different doses and withdrawal time of 4-vinylcyclohexene diepoxide （VCD） on the reproductive endocrine levels of female rats， and to explore the effective， stable， and safe dosage of VCD for constructing a premature ovarian insufficiency （POI） rat model. MethodSD rats with regular estrous cycles were randomly divided into three groups： blank group， low-dose VCD group （80 mg·kg^-1·d^-1）， and high-dose VCD group （160 mg·kg^-1·d^-1）， with 24 rats in each group. After drug intervention， samples were collected on the 15th day （D15） and the 45th day （D45） after intervention. The general condition， rate of estrous cycle disturbance， serum hormone levels， ovarian histomorphology， follicle count， pregnancy outcome， and the protein and mRNA expression of transforming growth factor （TGF）-β and Smad2/3 were assessed. ResultCompared with the blank group， the low-dose VCD group showed no significant differences in the rate of estrous cycle disturbance or serum follicle-stimulating hormone （FSH）， luteinizing hormone （LH）， and estradiol （E₂） levels. Ovarian tissue was damaged. Specifically， the number of primordial and primary follicles decreased on D15 （P<0.01）， and the number of secondary follicles （P<0.01） and antral follicles （P<0.05） further decreased on D45. The litter number decreased on D15 （P<0.05）， but there was no significant difference on D45. Furthermore， TGF-β protein levels increased on D15 （P<0.05） and D45 （P<0.01）. The Smad2/3 levels increased on D45 （P<0.01）， and TGF-β and Smad2/3 mRNA levels increased on D45 （P<0.05）. Compared with the results in the blank group， the disturbance rate of the estrous cycle increased on D45 in the high-dose VCD group （P<0.01）. The serum of FSH and LH increased （P<0.01）， while E₂ decreased （P<0.05）. Ovarian tissue was damaged， and the downward trend of follicles at all levels was similar to that in the low-dose VCD group. The litter number significantly decreased on D15 and D45. TGF-β and Smad2/3 protein levels increased （P<0.05，P<0.01）， and TGF-β mRNA increased on D45 （P<0.05）. ConclusionHigh-dose VCD is an ideal method for constructing a POI rat model， being effective， stable， and safe.