Establishment and characterization of a SV40T-transformed human bronchial epithelial cell line

Prognostic value of molecular events from negative surgical margin of non-small-cell lung cancer

It is hypothesized that the molecular status in negative surgical margin (NSM) is associated with prognosis of cancer patients. In this study, the prognostic relevance of Epithelial-to-Mesenchymal Transition (EMT) molecular events in NSMs in patients with NSCLC was investigated. EMT model was developed, in which the mesenchymal transition of human immortalized bronchial epithelial cell line was induced by TGF-beta1. Gene expression of EMT-induced cells and NSMs from 60 lung squamous cell carcinoma (SCC) patients was profiled by microarray and validated by quantitative RT-PCR. Two independent cohorts (lung SCC, n = 50; NSCLC, n = 54) were employed to validate the prognostic value of candidate genes. A set of 1490 genes were identified in EMT model in vitro. An EMT-like gene-expression pattern by 33 essential genes was optimized in NSMs, and was significantly associated with tumor progression. The 33 genes also exhibited a site-dependent field cancerization effect in the normal-appearing airways adjacent to NSCLCs. In the independent lung SCC cohort, the EMT-like active pattern indicated poor outcome of patients (n = 50, log-rank p = 0.009). Furthermore, in the NSCLC cohort, patients with EMT-like active pattern had shorter predictive survival time (n = 54, log-rank p = 0.02). In conclusion, the existence of EMT-like gene expression in NSMs, may play critical role in tumor progression and be a potential biomarker for prognosis in patients with NSCLC.

Suppression of non-small cell lung cancer proliferation and tumorigenicity by DENND2D

DENND2D was identified as being down-regulated in lung cancer using a lung cancer low-expression suppression subtractive hybridization (SSH) library. In this study, DENND2D down-regulation has been observed not only in non-small cell lung cancer (NSCLC) cell lines and lung squamous cell carcinoma (SCC) tissues, but also in immortalized human bronchial epithelial (IHBE) cell lines and precancerous lesions, indicating that the down-regulation of DENND2D may be an early event in lung cancer. The relative DNA copy number and mRNA and protein expression levels of DENND2D were determined in vitro, and they revealed a complicated regulatory network at the genomic, transcriptional and translational levels. Over-expression of DENND2D significantly suppressed the proliferation of NSCLC cells in vitro and in vivo by inducing apoptosis. These results indicate that DENND2D might function as a tumor suppressor-like gene to prevent the survival and expansion of cells with genetic damage through apoptosis mechanism, and absence of DENND2D might play a permissive role, as an early event, in tumorigenesis.

Overexpression of OLC1, cigarette smoke, and human lung tumorigenesis

BACKGROUND

Exposure to cigarette smoke is a major risk factor for lung cancer, but how it induces cancer is unclear. The overexpressed in lung cancer 1 (OLC1) gene is one of 50 candidate lung cancer genes identified by suppression subtractive hybridization as having higher expression in squamous cell carcinoma (SCC) than normal lung epithelia.

METHODS

We used immunohistochemistry (IHC) to measure OLC1 protein levels in primary lung cancer samples from 559 patients and used fluorescence in situ hybridization to measure OLC1 copy number in primary SCC samples from 23 patients. We compared OLC1 protein expression in SCC samples of 371 patients with and without a smoking history using the Pearson chi(2) test. We assayed OLC1 protein levels by immunoblotting in H1299 human lung cancer cells, immortalized human bronchial epithelial cells, and primary cultured normal human bronchial epithelial cells that were treated with cigarette smoke condensate. We assayed tumor formation in athymic mice using NIH3T3 mouse fibroblast cells transfected with OLC1 (eight mice) and analyzed apoptosis and colony formation of H1299 and H520 lung cancer cells transfected with scrambled (negative) or OLC1 small interfering RNAs (siRNAs) (s1).

RESULTS

OLC1 protein was overexpressed in 387 of 464 (83.4%) of primary lung cancers, as detected by IHC, and OLC1 was amplified in 14 of 23 (60%) of SCC samples. OLC1 protein overexpression was more common in SCC patients with a smoking history than those without (77.1% vs 45.8%, P < .001). In addition, cigarette smoke condensate increased OLC1 protein levels in H1299 cells, immortalized human bronchial epithelial cells, and primary cultured normal human bronchial epithelial cells. Overexpression of OLC1 induced tumor formation in athymic mice (control vs OLC1, 0% vs 100%). Knockdown of OLC1 increased apoptosis (mean percentage of apoptotic H1299 cells, s1 vs negative: 30.3% vs 6.4%, difference = 23.9%, 95% confidence interval [CI] = 19.1% to 28.5%, P = .002; mean percentage of apoptotic H520 cells, s1 vs negative: 21.6% vs 4.9%, difference = 16.7%, 95% CI = 10.6% to 22.8%, P = .007) and decreased colony formation (mean no. of colonies of H1299 cells transfected with siRNAs, negative vs s1: 84 vs 4, difference = 80, 95% CI = 71 to 88, P < .001; mean no. of colonies of H520 cells transfected with siRNAs, negative vs s1: 103 vs 24, difference = 79, 95% CI = 40 to 116, P = .005).

CONCLUSIONS

OLC1 is a candidate oncogene in lung cancer whose expression may be regulated by exposure to cigarette smoke.

Identification of genes differentially expressed in human primary lung squamous cell carcinoma

To identify differentially expressed genes in lung squamous cell carcinomas (SCCs), the suppression subtractive hybridization method (SSH) was performed comparing six lung tumour tissues and 10 morphologically normal bronchial epithelial tissues. A cDNA library consisting of 220 upregulated genes in tumour tissue was established and named as LSCC (lung squamous cell carcinoma). Of them, six were tested using semi-quantitative reverse transcription-PCR on 27 pairs of tumour tissue and normal lung tissue. Differential expression was confirmed in five of these six genes, including IGFBP5, SQLE, RAP2B, CLDN1, and TBL1XR1. The elevated mRNA expression of RAP2B, CLDN1 and TBL1XR1, three genes located on chromosome 3q, were further validated in 64.3% (18/28), 82.1% (23/28), and 75.0% (21/28) of lung SCC tumour tissues, respectively, by quantitative real-time reverse transcription-PCR analysis. Moreover, western blot analysis showed that the protein expression of TBL1XR1 was also upregulated in 53.3% (8/15) of lung SCC tumour samples, as well as in five lung cancer cell lines and in one human immortalized bronchial epithelial cell line. All the initial characteristics of these genes were first reported in the lung SCCs. The differentially expressed genes reported in this study will provide a valuable resource for understanding the pathogenesis of lung SCCs and for discovery of novel diagnostic or therapeutic targets.

An approach to studying lung cancer-related proteins in human blood

Early stage lung cancer detection is the first step toward successful clinical therapy and increased patient survival. Clinicians monitor cancer progression by profiling tumor cell proteins in the blood plasma of afflicted patients. Blood plasma, however, is a difficult cancer protein assessment medium because it is rich in albumins and heterogeneous protein species. We report herein a method to detect the proteins released into the circulatory system by tumor cells. Initially we analyzed the protein components in the conditioned medium (CM) of lung cancer primary cell or organ cultures and in the adjacent normal bronchus using one-dimensional PAGE and nano-ESI-MS/MS. We identified 299 proteins involved in key cellular process such as cell growth, organogenesis, and signal transduction. We selected 13 interesting proteins from this list and analyzed them in 628 blood plasma samples using ELISA. We detected 11 of these 13 proteins in the plasma of lung cancer patients and non-patient controls. Our results showed that plasma matrix metalloproteinase 1 levels were elevated significantly in late stage lung cancer patients and that the plasma levels of 14-3-3 sigma, beta, and eta in the lung cancer patients were significantly lower than those in the control subjects. To our knowledge, this is the first time that fascin, ezrin, CD98, annexin A4, 14-3-3 sigma, 14-3-3 beta, and 14-3-3 eta proteins have been detected in human plasma by ELISA. The preliminary results showed that a combination of CD98, fascin, polymeric immunoglobulin receptor/secretory component and 14-3-3 eta had a higher sensitivity and specificity than any single marker. In conclusion, we report a method to detect proteins released into blood by lung cancer. This pilot approach may lead to the identification of novel protein markers in blood and provide a new method of identifying tumor biomarker profiles for guiding both early detection and therapy of human cancer.

Identification of differentially expressed genes in human lung squamous cell carcinoma using suppression subtractive hybridization

Lung cancer is one of the major causes of cancer-related deaths. Over the past decade, much has been known about the molecular changes associated with lung carcinogenesis; however, our understanding to lung tumorigenesis is still incomplete. To identify genes that are differentially expressed in squamous cell carcinoma (SCC) of the lung, we compared the expression profiles between primarily cultured SCC tumor cells and bronchial epithelial cells derived from morphologically normal bronchial epithelium of the same patient. Using suppression subtractive hybridization (SSH), two cDNA libraries containing up- and down-regulated genes in the tumor cells were constructed, named as LCTP and LCBP. The two libraries comprise 258 known genes and 133 unknown genes in total. The known up-regulated genes in the library LCTP represented a variety of functional groups; including metabolism-, cell adhesion and migration-, signal transduction-, and anti-apoptosis-related genes. Using semi-quantitative reverse transcription-polymerase chain reaction, seven genes chosen randomly from the LCTP were analyzed in the tumor tissue paired with its corresponding adjacent normal lung tissue derived from 16 cases of the SCC. Among them, the IQGAP1, RAP1GDS1, PAICS, MLF1, and MARK1 genes showed a consistent expression pattern with that of the SSH analysis. Identification and further characterization of these genes may allow a better understanding of lung carcinogenesis.

Roles of p38 and c-jun in the differentiation, proliferation and immortalization of normal human endometrial cells

BACKGROUND

It has been reported that p38 and c-jun operate as mediators of cell proliferation and differentiation. Therefore, by studying the roles of c-jun and p38 in the proliferation and differentiation of normal human endometrial cells, we can better understand the mechanism of these processes in endometrial cells.

METHODS

Separation of glandular and stromal components was based on a modification of the work of Satyaswaroop et al. To confirm the purification of the endometrial cells and the expression of the transfected SV40 large T antigen, immunocytochemical analysis and western blot analysis were performed.

RESULTS

There were polygonal shapes in the stromal cells in the early passage 1-2, while the aged endometrial stromal cells were spindle shaped. To investigate passage-dependent molecular events in endometrial cells, the c-jun and pp38 levels were examined. Both c-jun and pp38 were significantly reduced with cellular aging and passages. To understand the role of c-jun, endometrial stromal cells were treated with SP600125 which is a specific inhibitor of c-jun. SP600125 induced morphological changes of young endometrial stromal cells with polygonal shape; the young cells appeared as aged endometrial cells with spindle shape. In addition, an immortalized endometrial cell line was established and shown to express activated c-jun, similiar to normal endometrial cells.

CONCLUSIONS

These results suggest that the modulation of p38 and c-jun may play an important role in the differentiation and proliferation of human endometrial cells.

Identification of differentially expressed genes in immortalized human bronchial epithelial cell line as a model for in vitro study of lung carcinogenesis

Suppression subtractive hybridization (SSH) was applied to identify differentially expressed genes in the SV40LT immortalized human bronchial epithelial cell line Y-BE, with normal human bronchial epithelial cells (HBEC) as a control. Two cDNA libraries of up- and downregulated genes were generated, comprising 218 known genes and 131 unknown genes in total. The expression of 22 clones from the 2 libraries was investigated by Northern blot analysis, and 86.4% (19/22) of them showed differential expression between Y-BE cells and HBEC. Although the Y-BE cells are nontumorigenic in nude mice, Comparative genomic hybridization (CGH) detected some DNA imbalances in Y-BE cells that were similar to lung cancer cells. Our data demonstrate that the studied cell line Y-BE and SSH is a reliable approach for identifying new genes that are associated with immortalization and early tumor development that may help to understand the pathogenesis of lung cancer.

Molecular and cytogenetic alterations in early stage of carcinogenesis of human lung

In an attempt to reveal the genetic and epigenetic abnormalities in early stage of carcinogenesis of human lung cancer, a human bronchial epithelial cell line was immortalized by transfection with the Simian virus early region genes (SV40T); the biological features of the stable transfected cells were compared to human non-small cell lung cancer (NSCLC) specimens. The immortalized bronchial epithelial cells did not develop tumors but premalignant lesions in animal models. However, several genetic changes, including chromosome deletion and aneuploidy, altered expression of oncogenes and tumor suppressor genes occur not only in invasive NSCLC (human specimens) but also in the early stage of lung carcinogenesis (premalignant lesions) in this transfection model.

Chromosome 3 imbalances are the most frequent aberration found in non-small cell lung carcinoma

The chromosomal imbalances in nine cases of primary non-small cell lung cancer (NSCLC) and two cell lines derived from normal human bronchial epithelial (HBE) tissue were identified by comparative genomic hybridization (CGH). Gain of material from 3q and loss of 3p material were the most frequent changes in the primary tumors. Other commonly found imbalances included gain of material from 1q, 7p, 8q, 9q, 17q and 20q, and losses involving 4, 5q, 8p, 10 and 13q. High level gain was found in two cases, both encompassing the 3q23-q27 region. Loss of 3p was also found in both of the HBE cell lines suggesting that loss of one or more tumor supressor genes on 3p may be important for epithelial transformation and could be involved in the earlier stages of lung cancer development.