Expression Of hnRNP B1 Research Articles

Mechanisms underlying regulation of cell cycle and apoptosis by hnRNP B1 in human lung adenocarcinoma A549 cells.

Overexpression of heterogeneous nuclear ribonucleoprotein B1 (hnRNP B1), a nuclear RNA binding protein, has been reported to occur in early-stage lung cancer and in premalignant lesions. DNA-dependent protein kinase (DNA-PK) is known to be involved in the repair of double-strand DNA breaks. Reduced capacity to repair DNA has been associated with the risk of lung cancer. We investigated a link between hnRNP B1 and DNA-PK and their effects on proliferation, cell cycle, and apoptosis in the human lung adenocarcinoma cell line A549. We found that hnRNP B1 and DNA-PK interact with each other in a complex fashion. Reducing hnRNP B1 expression in A549 cells with the use of RNAi led to upregulation of p53 activity through upregulation of DNA-PK activity but without inducing p53 expression. Further, suppression of hnRNP B1 in A549 cells slowed cell proliferation, promoted apoptosis, and induced cell cycle arrest at the G1 stage. The presence of NU7026 reduced the arrest of cells at the G1 stage and reduced the apoptosis rate while promoting cell growth. Taken together, our results demonstrate that by regulating DNA-PK activity, hnRNP B1 can affect p53-mediated cell cycle progression and apoptosis, resulting in greater cell survival and subsequent proliferation.

Comparison of Osteopontin, β-catenin and hnRNP B1 Expression in Lung Carcinomas

This study was performed to compare osteopontin (OPN), beta-catenin and heterogeneous nuclear ribonucleoprotein B1 (hnRNP B1) immunreactivities in small cell lung carcinomas (SCLC) and non-small cell lung carcinomas (NSCLC). Correlation of these three antibodies with grade and clinicopathologic stage of the tumor in NSCLC was also investigated. Twenty-nine SCLC, 6 large cell carcinoma, 36 adenocarcinoma and 30 squamous cell carcinoma (SCC), totally 101 cases, were included in this study. OPN, beta-catenin and hnRNP B1 expressions were immunohistochemically evaluated. OPN positivity was 6.9% in SCLC and 67% in NSCLC. When NSCLC types were individually considered, OPN positivity was 66.7% in large cell carcinoma, 80% in SCC and 55.6% in adenocarcinomas. beta-catenin positivity was observed in 48.6% of NSCLC and none of SCLC cases. These results were statistically significant (p < 0.05). Neither grade nor stage of NSCLC was correlated with osteopontin, beta-catenin or hnRNP B1 immunreactivity. We observed that OPN and beta-catenin are useful in differentiating SCLC from NSCLC. This may be helpful in small lung biopsies where morphology is obscured by crush artifacts.

The Expression Inhibition of HnRNP B1 in Lung Cell Line A549 by Small Interfering RNA

Background: Preliminary studies indicate a relative link between the expression of heterogeneous nuclear ribonucleoproteins (hnRNPs) and cancer. Overexpression of hnRNP B1 correlated with the eventual development of lung cancer. Here we describe inhibition of HnRNP B1 replication in human lung cell line A549 by siRNAs targeted to various regions of hnRNP B1 sequences. Methods: Small interfering RNA technique was used to interfer the expression of hnRNPB1 in Lung Cell Line A549 in vitro; the RT-PCR and Western blot technique were used to detect the quantity of hnRNPB1 mRNA and its protein; flow cytometry was used to detect the apoptosis; then the cells were transfected to nude mice. Results: We demonstrated that plasmidderived siRNAs could inhibit hnRNP B1 mRNA and protein expression, and the siRNA expressed from activated plasmid in A549 cells could suppress the cell proliferation by increasing the G1 cells. Our experiment also found that siRNA could induce apoptosis. Conclusions: These results demonstrated the effectiveness of siRNA in lung cancer cells, which indicated a possible clinical therapy method for lung cancer development.

Expression and value of hnRNP B1 in sputum of patients with lung cancer by immunohistochemistry method

The expression of heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 increases significantly in lung cancer tissues. The aim of this study is to investigate the expression of hnRNP B1 in exfoliative cells in the sputum of patients with lung cancer and its sensitivity and specificity in diagnosis of lung cancer. The expression of hnRNP B1 in sputum was detected by immunohistochemistry (IHC) using anti-hnRNP B1 monoclonal antibody in 70 patients with lung cancer and 30 normal subjects (control group). The results of sputum exfoliative cytology were 27 positive in 70 samples diagnosed with lung cancer, whose sensitivity and specificity were 38.6% and 100.0% respectively. The results of sputum immunohistochemistry were 50 positive in 70 samples, with 23 positive in 29 squamous cell carcinoma and 17 positive in 26 adenocarcinoma and 10 positive in 15 small cell lung carcinoma. Sputum IHC of hnRNP B1 gave a sensitivity of 71.4% and specificity of 93.3%. Sputum IHC of hnRNP B1 was more sensitive than sputum exfoliative cytology (P < 0.05). hnRNP B1 overexpresses in sputum exfoliative cells and its sensitivity is better than sputum exfoliative cytology in diagnosis of lung cancer.

Expression of hnRNP A2/B1 in human lung cancer cell lines

To explore the mRNA expression of heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 in human lung cancer cell lines. Expression of hnRNP A2/B1 and hnRNP B1 mRNA was detected by RT-PCR using specific primers. Expression of hnRNP B1 protein was examined by immunocytochemistry using specific anti-hnRNP B1 antibody. RT-PCR indicated that the hnRNP A2/B2 and hnRNP B1 mRNA existed in the lung adenocarcinoma cell lines SPC-A1 and Y-90, squamous cell carcinoma cell line A431 and small cell lung cancer cell line NCI-H446. According to immunocytochemistry results, the expression of hnRNP B1 was observed in lung cancer cell lines, but the expression in squamous cell carcinoma cell line A431 and small cell lung cancer cell line NCI-H446 was markedly higher than that in adenocarcinoma cell lines SPC-A1 and Y-90. The results suggest that the human lung cancer cell lines detected have overexpression of hnRNP A2/B1 and hnRNP B1.

HnRNP B1 protein may be a possible prognostic factor in squamous cell carcinoma of the lung

Heterogeneous nuclear ribonucleoprotein (hnRNP) B1 is an RNA-binding protein that is required for the maturation of mRNA precursor. It was previously reported that hnRNP A2/B1 was overexpressed at the early clinical stage of lung cancer, and that hnRNP B1 protein, a splicing variant of hnRNP A2 mRNA, was elevated in lung cancer tissues. In this study, we applied the immunohistochemical method, using anti-hnRNP B1 antibody to analyze the usefulness of the hnRNP B1 antibody as a prognostic marker and also as a marker useful for early detection. A total of 206 specimens were examined. Histological examination revealed this protein to be positive in 79 (71.2%) of 111 squamous cell carcinomas and in 45 (64.3%) of 70 adenocarcinomas, respectively. This protein was also expressed in 24 (63.2%) of 38 roentgenographically occult carcinomas and in seven (63.6%) of 11 dysplastic lesions. These findings suggest the possible participation of this protein in early carcinogenesis. Furthermore, the survival curve of the squamous cell carcinoma patients with hnRNP B1 overexpresseion showed a better prognosis compared with that of the patients without hnRNP B1 expression ( P=0.014), whereas in adenocarcinoma patients, there was no such a difference between them ( P=0.889). These findings indicate that hnRNP B1 could be a useful marker for the early detection of bronchogenic squamous cell carcinoma and that it may be a prognostic factor in this cell type.

HnRNP B1 expression in benign and malignant lung disease.

Evidence is accumulating to suggest that hnRNP B1 expression may be a useful tool in the early diagnosis of lung cancer. This study examined the immunohistochemical expression of hnRNP B1 in archived sections of resected lung cancers and compared the patterns of expression with those seen in similar archived sections of non-neoplastic lung. Particular attention was paid to the expression of hnRNP B1 in the benign bronchial cells in both cases, to establish if overexpression of this protein in respiratory epithelial cells is specific for malignancy. Nineteen cases of different types of non-small cell carcinoma were examined (eight squamous cell, six adenocarcinomas, two carcinosarcomas, two undifferentiated large cell carcinomas, and one mucoepidermoid carcinoma) and compared with sections from 16 open lung biopsies (three cases of cryptogenic fibrosing alveolitis, two cases of sarcoidosis, two cases of organizing pneumonia, and one case each of tuberculosis, extrinsic allergic alveolitis, non-specific interstitial pneumonitis, pneumocystis pneumonia, aspergilloma, respiratory bronchiolitis-interstitial lung disease, mineral dust disease, Sjögren's syndrome and systemic sclerosis vascular variant). All the tumours showed positive staining, with the vast majority, 16/19 (84%), showing strong diffuse nuclear staining. The background cells of these cases showed positive staining in alveolar macrophages, lymph node germinal centres, bronchial mucous glands, and bronchial epithelial cells. No significant difference was seen in the percentage of positive bronchial epithelial cells in bronchi adjacent to the tumour compared with the resection margins. In the benign lung cases, positive bronchial epithelial cells were seen in a small percentage, 3/16 (18%), of cases, but the majority of cases showed no or very focal staining. The levels of expression between benign epithelial cells of malignant cases, compared with benign, showed a significant difference when the staining was assessed in percentage of positive nuclei (p = 0.001, Fisher's exact test). The results confirm that hnRNP B1 is widely expressed in a range of lung carcinomas; that expression is seen in benign bronchial epithelial cells and inflammatory cells; and that expression in background bronchial epithelial cells appears to be higher in malignant than in benign lung disease. It is feasible that this biomarker may be of use in the detection of early lung cancer, provided that levels of expression can be accurately quantified.

Heterogeneous nuclear ribonucleoprotein B1 expressed in esophageal squamous cell carcinomas as a new biomarker for diagnosis.

We recently reported that heterogeneous nuclear ribonucleoprotein (hnRNP) B1 was overexpressed in most human lung cancers, especially squamous cell carcinoma (SCC), as well as human oral SCC. To find the significance of hnRNP B1 in cancer diagnosis, we studied hnRNP B1 expression in 16 paraffinized sections of esophageal SCC, using immunohistochemical staining with antihnRNP B1 polyclonal antibody, raised in a rabbit. We compared the expression of hnRNP B1 in cancerous and noncancerous regions of the same specimen: enhanced expression was observed in 63% of cancerous regions (10/16), whereas none of the noncancerous regions showed enhanced expression. The enhanced expression of hnRNP B1 in cancerous regions was compared with that in noncancerous tissue in relation to histopathological grade: 83% for well differentiated (5/6), 83% for moderately differentiated (5/6) and 0% for poorly differentiated (0/4). Histologically, enhanced expression of hnRNP B1 was observed around cancer pearls, as well as in the cells of nests lacking keratinization in well and moderately differentiated SCC. Western blotting analysis revealed enhanced expression in three frozen specimens of moderately differentiated SCC. Using esophageal cancer cell lines, we further confirmed the decreased expression in poorly differentiated SCC cells, compared with other differentiation types. All our results support the significance of hnRNP B1 expression in esophageal SCC as a unique diagnostic marker with regard to association between expression level and histopathological grading.