| Bromodomain containing protein 4(BRD4) belongs to the protein of the bromodomain and extraterminal domain(BET) family. Similar to its BET family members, BRD4 includes two bromodomains that recognize acetylated lysine residues. BRD4 is the best studied member of the BET family and it plays an important role in various biological processes by means of its two bromodomains(BRDs). More importantly, recent studies have also showed that BRD4 activation may also predict the overall survival of patients with several tumors, such as melanoma, hepatocellular carcinoma, multiple myeloma, Burkitt’s lymphoma, acute myeloid leukemia and breast cancer. In addition, the ectopic fusion product BRD4-NUT is associated to more than half of the invasive tumors. Our previous screens also showed that BRD4 closely correlated to the invasion of NSCLC, thus BRD4 can be used as a potential prognosticator of NSCLC. The present study detected the expression level of BRD4 in NSCLC and their corresponding adjacent normal lung tissues. Using tissue microarray technique, we analyzed the relationship between BRD4 expression and clinicopathological characteristics of NSCLC and as well its prognostic value. In addition, by RNA interference, we observed that BRD4 was closely associated to tumor proliferation, invasion, migration and apoptosis of NSCLC. Thus, we concluded that BRD4 had potential prognostic value and could be served as a novel therapeutic target, which brought NSCLC patients with new prospects.Part 1 High expression of BRD4 in Non-Small Cell Lung Cancer Objective: To investigate the expression of BRD4 in NSCLC tumor and peritumor tissues and its role in carcinogenesis of NSCLC.Methods: The expression of BRD4 was evaluated in NSCLC tissues and adjacent non-tumorous tissues by q RT-PCR, Western Blot and immunohistochemistry.Results: The results of all the above mentioned methods consistently showed BRD4 expression was elevated in NSCLC tissues compared to corresponding adjacent peritumor tissues(P<0.05).Conclusions: BRD4 highly expressed in NSCLC tissues and might be related to the carcinogenesis of NSCLC.Part 2 The prognostic value of BRD4Objective: To investigate the association between BRD4 level and clinicalpathological characteristics of NSCLC and as well as its prognostic value.Methods: Immunohistochemistry was applied in the TMA of 208 NSCLC patients’ samples to detect the expression of BRD4, then the correlation between BRD4 expression and the clinicalpathological characteristics and prognosis was analyzed by SPSS 19.0.Results: The results showed that high level of BRD4 was associated with lung squamous cell cancer, lymphatic metastasis, TNM stage III-IV and poor differentiation in NSCLC tissues(P<0.05). Compared with BRD4 lo patients, BRD4 hi patients had a lower OS(P<0.05). BRD4 was an independent prognosis factor for OS in univariate and multivariate analysis.Conclusions: BRD4 expression was closely related to histopathological types,lymphatic metastasis, TNM stage and differentiation and the high level of BRD4 could indicate poor prognosis in NSCLC patients.Part 3 The influences of BRD4 exerting on NSCLC cell biological behaviors Objective: To investigate the relationship of BRD4 with the proliferation, invasion,migration and apoptosis in NSCLC cells.Methods: BRD4 expression was knocked down in A549 and 95-D cells by RNA interference. Decreased BRD4 expression was validated by Western Blot and FACS.The wound healing, transwell, CCK-8, Brd U and FACS assays were respectively used to determine the cells’ migration, invasion, proliferation and apoptosis.Results: BRD4 expression in A549 and 95-D cells was reduced by vsh RNA successfully. Decreased BRD4 expression was accompanied by weakenedproliferation, impaired invasiveness and migration and increased apoptosis in NSCLC cells(P<0.05).Conclusions: BRD4 possesses the potential of promoting proliferation, invasion,migration and inhibiting apoptosis in NSCLC cells. |
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