Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0596263 (carcinogenesis)
 64,820 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The process of bronchial carcinogenesis is characterized by accumulated genetic abnormalities which ultimately lead to malignant transformation of bronchial epithelial cells, followed by invasion and metastasis. One of the most common and consistent of these genetic lesions is inactivation of the p53 tumor suppressor gene by mutation or deletion. The frequency of p53 alterations in lung cancer is highest in those subtypes of bronchial carcinomas that are most consistently associated with smoking, especially SCLC and squamous cell carcinomas. The frequency is lower in adenocarcinomas, in which the association with smoking, although present, is not as strong. The frequency of p53 abnormalities is higher in patients with greater cumulative tobacco exposure. Tobacco-specific carcinogens, in particular BPDE, cause a unique spectrum of p53 mutations, quite distinct from those found in cancers that are not associated with smoking. This characteristic genetic "signature" may persist even decades following smoking cessation. The prognostic significance of p53 mutations in lung cancer is not entirely clear despite the multitude of clinical studies that have been carried out. Nevertheless, the majority of clinical studies suggest that lung cancers with p53 alterations carry a worse prognosis. Furthermore, those tumors with mutant p53 may be relatively more resistant to chemotherapy and radiation. An understanding of the role of p53 in human lung cancer may lead to more rational targeted approaches for treating this disease. For example, the observation that the introduction of wild-type p53 into lung cancer cells with mutant or deleted p53 may reverse the malignant phenotype despite the presence of multiple other genetic abnormalities (14) suggests that replacement of this gene may be an effective clinical strategy. Preclinical and early clinical studies indicate that this is a promising approach, but clearly more effective means of gene delivery to the tumor cells are required (127-129), as discussed elsewhere in this volume.
 ...
PMID:Clinical implications of p53 mutations in lung cancer. 1240 35

TMS1 (target of methylation-induced silencing) is a CpG island-associated gene that functions in the regulation of apoptosis and encodes a caspase recruitment domain, a recently described motif found in apoptotic signaling molecules. Recent evidence suggests that silencing of genes in the apoptotic pathway contribute to human carcinogenesis. We examined the DNA methylation status of the TMS1 promoter in lung and breast tumor tissues, tumor cell lines and nonmalignant tissues by methylation-specific polymerase chain reaction (MSP) and its mRNA expression by reverse transcription PCR. Aberrant methylation of TMS1 was present in 70% (40 of 57) of small cell lung cancer (SCLC) cell lines and 41% (13 of 32) of SCLC tumor tissues, 48% (29 of 61) of non small cell lung cancer (NSCLC) cell lines and 40% (28 of 70) of NSCLC tumor tissues and 46% (12 of 26) of breast cancer cell lines and 32% (20 of 63) of breast tumor tissues. Methylation was absent in the peripheral blood lymphocytes and buccal epithelium from healthy volunteers, as well as in nonmalignant lung tissues and was rare in nonmalignant breast tissues 7% (2 of 30). DNA methylation was confirmed by sequence analysis and the methylation status correlated inversely with TMS1 RNA expression in 18 cell lines tested. RNA expression was restored by treatment with the demethylating agent 5-aza-2'-deoxycytidine, in 4 of 4 methylated cell lines that lacked the TMS1 transcript. Our results suggest that methylation of TMS1 may play a role in the pathogenesis of small cell and non small lung and breast cancers.
 ...
PMID:Aberrant methylation of TMS1 in small cell, non small cell lung cancer and breast cancer. 1280 Jan 94

DNA repair plays a critical role in protecting the genome from insults of cancer-causing agents, such as those found in tobacco smoke. Therefore, reduced DNA repair capacity can increase the susceptibility to smoking-related cancers. Recently, several polymorphisms have been identified in the xeroderma pigmentosum group G (XPG) gene, and it is possible that these polymorphisms may affect the DNA repair capacity, thereby modulating cancer susceptibility. We investigated the relationship between the His1104Asp polymorphism in the XPG gene and the risk of lung cancer. The study population consisted of 310 lung cancer patients and 311 healthy controls who were frequency (1:1) matched based on age and sex. The Asp/Asp genotype was more frequent in the controls (28.9%) than in the cases (18.7%) and associated with a significantly decreased risk of lung cancer [adjusted odds ratio (OR) = 0.54, 95% confidence interval (CI) = 0.37-0.80] when the combined His/His and His/Asp genotype was used as the reference. The protective effect of the Asp/Asp genotype against lung cancer was statistically significant in the older subjects (adjusted OR = 0.51, 95% CI = 0.37-0.80), males (adjusted OR = 0.54, 95% CI = 0.35-0.83), and lighter smokers (adjusted OR = 0.48, 95% CI = 0.25-0.94) in a stratification analysis. When the lung cancers were analyzed by histologic type, the Asp/Asp genotype was associated with a significantly decreased risk of squamous cell carcinoma (adjusted OR = 0.55, 95% CI = 0.34-0.88) and small cell lung cancer (adjusted OR = 0.44, 95% CI = 0.20-0.97), but non-significant decreased risk of adenocarcinoma (adjusted OR = 0.64, 95% CI = 0.36-1.12). These results suggest that the XPG codon 1104 polymorphism contributes to genetic susceptibility to lung cancer.
Carcinogenesis 2003 Oct
PMID:Relationship between XPG codon 1104 polymorphism and risk of primary lung cancer. 1286 23

Many cancer and immortal cells exhibit telomerase activity that stabilizes telomere lengths, possibly contributing to cell immortality and carcinogenesis. The aim of this study was to elucidate the clinicopathological relationship between telomerase activity and telomerase reverse transcriptase subunit (hTERT) status in non small cell lung cancer. hTERT status in non small cell lung cancer using telomeric repeat amplification protocol (TRAP) and RT-PCR assay, respectively. Telomerase activity and hTERT were detected in 85.7 and 80.3% of cancerous tissues, respectively. Telomerase activity does not correlate with clinicopathological variables. However, there was an association between p53-correlated expression and hTERT negative status. Lung cancer patients without telomerase activity survived for a significantly longer period than those with telomerase activity. In addition, hTERT was not associated with the prognosis. TERT expression did not correlate well with any clinical parameter. Reactivated telomerase activity may be a poor prognostic factor in NSCLCs.
 ...
PMID:Loss of telomerase activity may be a potential favorable prognostic marker in lung carcinomas. 1287 79

p120 RasGTPase-activating protein (RasGAP), the main regulator of Ras GTPase family members, is cleaved at low caspase activity into an N-terminal fragment that triggers potent anti-apoptotic signals via activation of the Ras/PI-3 kinase/Akt pathway. When caspase activity is increased, RasGAP fragment N is further processed into two fragments that effectively potentiate apoptosis. Expression of RasGAP protein and its cleavage was assessed in human lung cancer cells with different histology and responsiveness to anticancer drug-induced apoptosis. Here we show that therapy-sensitive small lung carcinoma cell (SCLC) lines have lower RasGAP expression levels and higher spontaneous cleavage with formation of fragment N compared to therapy-resistant non-small cell lung carcinoma cell (NSCLC) lines. The first RasGAP cleavage event strongly correlated with the increased level of spontaneous apoptosis in SCLC. However, generation of protective RasGAP fragment N also related to the potency of SCLC to develop secondary therapy-resistance. In response to etoposide (ET), RasGAP fragment N was further cleaved in direct dependence on caspase-3 activity, which was more pronounced in NSCLC cells. Caspase inhibition, while effectively preventing the second cleavage of RasGAP, barely affected the first cleavage of RasGAP into fragment N that was always detectable in NSCLC and SCLC cells. These findings suggest that different levels of RasGAP and fragment N might play a significant role in the biology and different clinical course of both subtypes of lung neoplasms. Furthermore, constitutive formation of RasGAP fragment N can potentially contribute to primary resistance of NSCLC to anticancer therapy by ET but also to secondary therapy-resistance in SCLC.
Carcinogenesis 2004 Jun
PMID:RasGTPase-activating protein is a target of caspases in spontaneous apoptosis of lung carcinoma cells and in response to etoposide. 1474 24

Aberrant activation of the Wingless-type (Wnt)/beta-catenin signaling pathway is associated with a variety of human cancers. Little is known regarding the role that Wnt ligands play in human carcinogenesis. To test whether a Wnt-1 signal is a survival factor in human cancer cells and thus may serve as a potential cancer therapeutic target, we investigated the effect of inhibition of Wnt-1 signaling in a variety of human cancer cell lines, including non small cell lung cancer, breast cancer, mesothelioma, and sarcoma. Both monoclonal antibody and RNA interference (RNAi) were used to inhibit Wnt-1 signaling. We found that incubation of a monoclonal anti-Wnt-1 antibody induced apoptosis and caused downstream protein changes in cancer cells overexpressing Wnt-1. In contrast, apoptosis was not detected in cells lacking or having minimal Wnt-1 expression after the antibody incubation. RNAi targeting of Wnt-1 in cancer cells overexpressing Wnt-1 demonstrated similar downstream protein changes and induction of apoptosis. The antibody also suppressed tumor growth in vivo. Our results indicate that both monoclonal anti-Wnt-1 antibody and Wnt-1 siRNA inhibit Wnt-1 signaling and can induce apoptosis in human cancer cells. These findings hold promise as a novel therapeutic strategy for cancer.
 ...
PMID:A monoclonal antibody against Wnt-1 induces apoptosis in human cancer cells. 1506 66

Neuroblastoma is a neural crest-derived neoplasm of infancy with poor outcome in patients with advanced disease. The oncogenic transcription factor PAX5 is an important developmental regulator and is implicated in the pathogenesis of several malignancies. Screening of neuroblastoma cell lines revealed PAX5 expression in a malignant subset of neuroblastoma cells, so-called 'N-type' cells, but not in the more benign 'S-type' neuroblastoma cells. PAX5 expression was also detected in small cell lung cancer, an aggressive tumor of neural crest origin. Based on this observation we hypothesized that there could be a relationship between PAX5 expression and the more malignant phenotype of N-type cells. Stable PAX5 expression was established in several clones of the S-type cell line CA-2E. A noticeable difference in morphology of these transfectants was observed and there was also a significant increase in the proliferation rate. Moreover, PAX5 expressing clones gained the ability to form colonies in a soft agar assay, a marker of tumorigenicity. Down-regulation of PAX5 in several N-type cell lines and one small cell lung cancer cell line utilizing small interfering RNA resulted in a significant decrease in growth rate. Taken together we propose PAX5 as an important factor for the maintenance of the proliferative and tumorigenic phenotype of neuroblastoma. Our data, together with a recent study on the role of PAX genes in cancer suggest that PAX5 and other PAX transcription factors might be valuable targets for cancer therapy.
Carcinogenesis 2004 Oct
PMID:The PAX5 oncogene is expressed in N-type neuroblastoma cells and increases tumorigenicity of a S-type cell line. 1515 32

Lung cancer continues to be the leading cause of cancer death in developed countries. With smoking the major etiological factor for lung cancer, there is a great need for the development of chemopreventive treatments that inhibit the progression of initiated cells and premalignant lesions into overt lung cancer in smokers who quit. Although the major focus of chemoprevention research has been on agents that inhibit the metabolic activation of genotoxic chemicals contained in tobacco products, some of these agents may additionally modulate growth-regulating signal transduction. In turn, the function of such signaling pathways is highly cell type-specific, with a given pathway inhibiting the growth of one cell type while stimulating the growth of others. The current experiment has tested the hypothesis that green tea and the methylxanthine theophylline contained in tea inhibit the progression of neuroendocrine lung carcinogenesis in hamsters with hyperoxic lung injury and initiated with the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) while promoting the development of Clara cell-derived pulmonary adenocarcinomas initiated by NNK in healthy hamsters. This hypothesis is based on published evidence that human small cell lung cancer as well as the neuroendocrine hamster tumors are regulated via autocrine signaling pathways that activate Raf-1 and the mitogen-activated (MAP) kinase pathway whereas human pulmonary adenocarcinomas of Clara cell lineage and the hamster model of this cancer type are regulated by a beta-adrenergic pathway involving the activation of cyclic adenosine 3',5'-monophosphate (cAMP) and the arachidonic acid (AA) cascade. In turn, it was hypothesized that theophylline would inhibit Raf-1-dependent tumor progression while promoting cAMP-dependent tumor progression due to its documented ability to inhibit the enzyme cAMP-phophodiesterase. The experimental design simulated chemoprevention in former smokers in that treatments with tea or theophylline started after completion of a 10-week tumor induction period with NNK. Our data show that green tea as well as theophylline significantly inhibited lung tumor multiplicity in the neuroendocrine cancer model whereas identical chemopreventive treatments significantly promoted the lung tumor multiplicity in the adenocarcinoma model. These findings indicate that green tea and theophylline as well as other chemopreventive agents that modulate signal transduction may have opposite effects on cancers of different histolopathology and cell lineage. At the current state of knowledge such chemopreventive treatments should only be used as adjuvant to cancer therapy of cancers that have been fully characterized at the pathology and molecular level.
 ...
PMID:Neuroendocrine lung carcinogenesis in hamsters is inhibited by green tea or theophylline while the development of adenocarcinomas is promoted: implications for chemoprevention in smokers. 1519 29

alpha CP-4 is an RNA-binding protein coded by PCBP4, a gene mapped to 3p21, a common deleted region in lung cancer. In this study we characterized the expression of alpha CP-4 and alpha CP-4a, an alternatively spliced variant of alpha CP-4, in lung cancer cell lines and non-small cell lung cancer (NSCLC) samples from early stage lung cancer patients. In NSCLC biopsies, an immunocytochemical analysis showed cytoplasmic expression of alpha CP-4 and alpha CP-4a in normal lung bronchiolar epithelium. In contrast, alpha CP-4 immunoreactivity was not found in 47% adenocarcinomas and 83% squamous cell carcinomas, whereas all of the tumors expressed alpha CP-4a. Besides, lack of alpha CP-4 expression was associated with high proliferation of the tumor (determined by Ki67 expression). By fluorescence in situ hybridization, >30% of NSCLC cell lines and tumors showed allelic losses at PCBP4, correlating with the absence of the protein. On the other hand, no mutations in the coding region of the gene were found in any of the 24 cell lines analyzed. By Northern blotting and real-time reverse transcription-PCR, we detected the expression of alpha CP-4 and alpha CP-4a messages in NSCLC and small cell lung cancer cell lines. Our data demonstrate an abnormal expression of alpha CP-4 in lung cancer, possibly associated with an altered processing of the alpha CP-4 mRNA leading to a predominant expression of alpha CP-4a. This may be considered as an example of alternative splicing involved in tumor suppressor gene inactivation. Finally, induction of alpha CP-4 expression reduced cell growth, in agreement with its proposed role as a tumor suppressor, and suggesting an association of this RNA-binding protein with lung carcinogenesis.
 ...
PMID:Alpha CP-4, encoded by a putative tumor suppressor gene at 3p21, but not its alternative splice variant alpha CP-4a, is underexpressed in lung cancer. 1520 28

The identification of genes undergoing genetic or epigenetic alterations and contributing to the development of cancer is critical to our understanding of the molecular mechanisms of carcinogenesis. A new approach in identifying alterations of genes that might be relevant to the process of tumor development was used in this study by examining the gene expression profile in human lung cancer cells exposed to 5-aza-2'-deoxycytidine (5-aza-dC). A cDNA array analysis was carried out on 5-aza-dC-treated and untreated non small cell lung cancer (NSCLC) cell line NCI-H522. Sixteen and 14 genes were upregulated and downregulated, respectively, by 5-aza-dC treatment. Among them, downregulation of tyrosine protein kinase ABL2 (ABL2) gene and upregulation of hint/protein kinase C inhibitor 1 (Hint/PKCI-1), DVL1, TIMP-1, and TRP-1 genes were found in expanded observations in two or three of five 5-aza-dC-treated NSCLC cell lines. Among these genes, we found that cDNA transfer of Hint/PKCI-1 resulted in a significant in vitro growth inhibition in two cell lines exhibiting 5-aza-dC-induced upregulation of Hint/PKCI-1 and significantly reduced in vivo tumorigenicity of one NSCLC cell line. Hint/PKCI-1, which is the only other characterized human histidine triad (HIT) nucleotide-binding protein in addition to tumor-suppressor gene FHIT, might be involved in lung carcinogenesis.
 ...
PMID:Aberrant gene expression in human non small cell lung carcinoma cells exposed to demethylating agent 5-aza-2'-deoxycytidine. 1525 63


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>