[Effects of theaflavins on the signal transduction pathway of epidermal growth factor receptor in airway mucous hypersecretion].
OBJECTIVE
To investigate the effects of theaflavins (TFs) on airway mucous hypersecretion and on the signal transduction pathway of epidermal growth factor receptor (EGFR).


METHODS
The cell model of mucous hypersecretion was made by human lung A549 cell stimulated by human neutrophil elastase (HNE), and treated with TFs and AG1478, a blocking agent of EGFR. The expression of mucin (MUC) 5AC, EGFR, P-EGFR, phosphorylation extracellular signal regulated kinase 1/2 (P-ERK1/2), P-p38, phosphorylation c-Jun N-terminal kinase (P-JNK) were detected. The cell activity after TFs treatment was assessed by methyl thiazolyl tetrazolium method. The cells were divided into 5 groups: a negative control group, an HNE treatment group, a TFs pre-treatment group, an AG1478 pre-treatment group and a TFs + AG1478 group. The changes of MUC5AC mRNA and EGFR mRNA were examined by the use of reverse transcriptase-polymerase chain reaction (RT-PCR). The protein expression changes of EGFR, P-EGFR, P-ERK1/2, P-p38 and P-JNK were measured by Western blot. The protein expression changes of MUC5AC were detected by enzyme-linked immunosorbent assay, while the protein morphological changes of MUC5AC were observed by immunofluorescence and confocal laser technology. The data were analyzed with SPSS 12.0 software. Differences between groups were assessed for significance by t test.


RESULTS
The expression levels of MUC5AC mRNA and its protein in the HNE group were (0.99 +/- 0.03) and (169 +/- 6) microg/mg, and those of EGFR were (0.98 +/- 0.02) and (0.89 +/- 0.03), both of them increased significantly as compared to those in the control group [(0.53 +/- 0.02), (105 +/- 4) microg/mg and (0.61 +/- 0.11), (0.21 +/- 0.05)]. The protein expressions of P-EGFR, P-ERK1/2, P-p38 were increased significantly as compared with the control group. But the increase of P-p38 was not significant as compared to P-ERK1/2. The protein expression of P-JNK did not change markedly. After the cells were pre-treated with TFs and AG1478 respectively, the above measurements were decreased significantly as compared with the HNE group. The decrease was more significant in the TFs + AG1478 group (t = 3.02, P < 0.05).


CONCLUSIONS
Theaflavins decreased the level of EGFR and inhibited the activation of EGFR, and attenuated airway mucous hypersecretion via the ERK pathway.
Wu
Hai-Qiao
HQ
Department of Respiratory Medicine, Second Affiliated Hospital, Chongqing Medical University, Chongqing 400010, China.
Li
Qi
Q
Zhou
Xiang-Dong
XD
D044946:Biflavonoids / Q000494:pharmacology*; D002392:Catechin / Q000494:pharmacology*; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D055271:Mucin 5AC / Q000378:metabolism; D010766:Phosphorylation; D011799:Quinazolines; D020545:Respiratory Mucosa / Q000187:drug effects* / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D020032:Tyrphostins / Q000378:metabolism
D044946:Biflavonoids; D055271:Mucin 5AC; D011799:Quinazolines; D020032:Tyrphostins; C101044:RTKI cpd; C056068:theaflavin; D002392:Catechin; C512478:EGFR protein, human; D066246:ErbB Receptors; D048031:JNK Mitogen-Activated Protein Kinases