Wnt and Hedgehog Are Critical Mediators of Cigarette Smoke-Induced Lung Cancer (original) (raw)
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Interdisciplinary Toxicology, 2014
The A/J mouse is highly susceptible to lung tumor induction and has been widely used as a screening model in carcinogenicity testing and chemoprevention studies. However, the A/J mouse model has several disadvantages. Most notably, it develops lung tumors spontaneously. Moreover, there is a considerable gap in our understanding of the underlying mechanisms of pulmonary chemical carcinogenesis in the A/J mouse. Therefore, we examined the differences between spontaneous and cigarette smokerelated lung tumors in the A/J mouse model using mRNA and microRNA (miRNA) profiling. Male A/J mice were exposed whole-body to mainstream cigarette smoke (MS) for 18 months. Gene expression interaction term analysis of lung tumors and surrounding nontumorous parenchyma samples from animals that were exposed to either 300 mg/m 3 MS or sham-exposed to fresh air indicated significant differential expression of 296 genes. Ingenuity Pathway Analysis® (IPA®) indicated an overall suppression of the humoral immune response, which was accompanied by a disruption of sphingolipid and glycosaminoglycan metabolism and a deregulation of potentially oncogenic miRNA in tumors of MS-exposed A/J mice. Thus, we propose that MS exposure leads to severe perturbations in pathways essential for tumor recognition by the immune system, thereby potentiating the ability of tumor cells to escape from immune surveillance. Further, exposure to MS appeared to affect expression of miRNA, which have previously been implicated in carcinogenesis and are thought to contribute to tumor progression. Finally, we identified a 50-gene expression signature and show its utility in distinguishing between cigarette smoke-related and spontaneous lung tumors.
Activation of the hedgehog pathway in a subset of lung cancers
Cancer Letters, 2006
Activation of the hedgehog pathway is reported in lung cancer, but its frequency remains unknown. We examine activation of this pathway in lung cancers by in situ hybridization and immunohistochemstry, and find that less than 10% of the tumors have elevated hedgehog target gene expression. We further identify a cell line NCI-H209 and two primary tumors with no detectable Su(Fu), a negative regulator of the pathway. Ectopic expression of Su(Fu) in NCI-H209 cells down-regulates hedgehog target gene expression and leads to inhibition of cell proliferation. These data indicate that activation of the hedgehog pathway is activated through Shh over-expression or Su(Fu) inactivation in only a subset of lung cancers.
Frequent requirement of hedgehog signaling in non-small cell lung carcinoma
Oncogene, 2007
Although it had previously been suggested that the hedgehog (HH) pathway might be activated in some lung tumors, the dependence of non-small cell lung carcinomas (NSCLC) for HH activity had not been comprehensively studied. During a screen of a panel of 60 human tumor cell lines with an HH antagonist, we observed that the proliferation of a subset of NSCLC cell lines was inhibited. These NSCLC cell lines express HH, as well as key HH target genes, consistent with them being activated through an autocrine mechanism. Interestingly, we also identified a number of NSCLC cell lines that express high levels of the downstream transcription factor GLI1 and harbor enhanced levels of HH activity, but appear insensitive to known HH antagonists. We hypothesized that the high levels of GLI1 in these cells would function downstream of the HH antagonist target, allowing them to bypass the antagonist-mediated block in proliferation. Consistent with this hypothesis, when the levels of GLI1 are knocked down in such cells, they become sensitive to these inhibitors. We go on to show that a large percentage of primary NSCLC samples express GLI1, consistent with constitutive activation of the HH pathway in these samples. Taken together, these results establish the involvement of the HH signaling pathway in a subset of NSCLCs.
Scientific Reports , 2020
Lung malignancies comprise lethal and aggressive tumours that remain the leading cancer-related death cause worldwide. Regarding histological classification, lung squamous cell carcinoma (LUSC) and adenocarcinoma (LUAD) account for the majority of cases. Surgical resection and various combinations of chemo-and radiation therapies are the golden standards in the treatment of lung cancers, although the five-year survival rate remains very poor. Notch, Hedgehog, Wnt and Erbb signalling are evolutionarily conserved pathways regulating pivotal cellular processes such as differentiation, proliferation, and angiogenesis during embryogenesis and post-natal life. However, to date, there is no study comprehensively revealing signalling networks of these four pathways in LUSC and LUAD. Therefore, the aim of the present study was the investigation profiles of downstream target genes of pathways that differ between LUSC and LUAD biology. Our results showed a few co-expression modules, identified through weighted gene co-expression network analysis (WGCNA), which significantly differentiated downstream signaling of Notch, ErbB, Hedgehog, and Wnt in LUSC and LUAD. Among co-expressed genes essential regulators of the cell cycle, DNA damage response, apoptosis, and proliferation have been found. Most of them were upregulated in LUSC compared to LUAD. In conclusion, identified downstream networks revealed distinct biological mechanisms underlying cancer development and progression in LUSC and LUAD that may diversify the clinical outcome of the disease. Lung carcinomas remain one of the most aggressive malignancies characterized by the highest mortality rate among men and women worldwide 1,2. Regarding histological classification lung squamous cell carcinoma (LUSC) and adenocarcinoma (LUAD) account for the majority of lung tumours in non-small cell carcinomas (NSCLCs). In general, the NSCLCs are treated with surgery, which remains the key treatment option, accompanied by various modalities of chemotherapy and radiation. Nevertheless, the five-year survival rate is very poor 3 and patients experience early events of relapse, metastasis and death 4. Despite that both LUAD and LUSC, belong to the family of NSCLCs, they seem very distinct in terms of prognosis as well as the composition of gene expression and signalling pathways profiles. Importantly, more and more often they are being considered as separate clinical entities 5. LUAD comprises about 40% of all lung cancer cases. In the majority of patients, LUAD mostly affects non-smokers but is also observed among smokers. Usually, the tumour is located more peripherally and grows slower than the other types, although it tends to form metastasis at the early stages of the disease. LUSC, in turn, is the second most common lung malignancy among tobacco smokers. Its pathogenesis is strongly associated with airway lesions that arise with smoking and is mostly located in the central parts of the lung. LUSC is also regarded as a very heterogeneous entity, among which two major subtypes may be distinguished such as basaloid and non-basaloid tumours 6. Interestingly, lung cancer shows one of the most diverse genetic landscape harbouring numbers of mutations and copy number
Toxicology, 2013
A generally accepted and validated laboratory model for smoking-associated pulmonary tumorigenesis would be useful for both basic and applied research applications, such as the development of early diagnostic endpoints or the evaluation of modified risk tobacco products, respectively. The A/J mouse is susceptible for developing both spontaneous and induced lung adenomas and adenocarcinomas, and increased lung tumor multiplicities were also observed in previous cigarette smoke inhalation studies. The present study was designed to collect data useful towards the validation of an 18-month mainstream smoke (MS) inhalation model. Male and female A/J mice were exposed whole-body at three MS concentration levels for 6 h/day, and the results were compared to a previous study in the same laboratory and with a similar design. A linear MS concentration-dependent increase in lung tumorigenesis was observed with similar slopes for both sexes and both studies and a maximal 5-fold increase in multiplicity beyond sham control. The minimal detectable difference in lung tumor multiplicity for the current study was 37%. In the larynx, papillomas were detectable in all MS-exposed groups in a non-concentration dependent manner. No other extra-pulmonary MS-dependent neoplastic lesions were found. Gene expression signatures of lung tumor tissues allowed a clear differentiation of sham-and high dose MS-exposed mice. In combination with data from previous smoke inhalation studies with A/J mice, the current data suggest that this model for MS inhalation-induced pulmonary tumorigenesis is reliable and relevant, two crucial requirements towards validation of such a model.
A Mouse Lung Tumor Model of Tobacco Smoke Carcinogenesis
Toxicological Sciences, 2002
We examined the possibility of developing an animal model of tobacco smoke carcinogenesis. Male Balb/c and SWR mice were exposed for 5 months to tobacco smoke (6 h/day, 5 days/week; average concentration, 122 mg/m 3 of total suspended particulates [TSP]) followed by a recovery period of 4 months in air. In both strains there was an increase in lung tumor multiplicities and incidence, although statistical significance was only observed with lung tumor multiplicity in the SWR mice. An analysis of 11 previous and independently conducted assays with strain A/J mice that followed the same protocol was performed. In each experiment, lung tumor multiplicities were significantly higher in tobacco smoke-exposed mice compared with air-exposed controls, and a good correlation between exposure (average tobacco smoke concentrations multiplied by length of exposure in months) and lung tumor multiplicities was found. In 7 experiments involving tobacco smoke concentrations greater than 100 mg/m 3 of TSP, lung tumor incidences were 5 times higher than in control mice. Tobacco smoke-exposed mice had a smaller percentage of adenomas with carcinomatous foci or adenocarcinomas than air-exposed controls, and no differences between the two groups were found in an analysis of Ki-ras mutations. After 6 h of exposure to tobacco smoke, plasma cotinine levels in mice were comparable to those found in active human smokers. The lung tumor model might be suitable for future evaluation of chemopreventive agents or modified tobacco products.
PLoS ONE, 2013
The majority of lung cancers (LC) belong to the non-small cell lung carcinoma (NSCLC) type. The two main NSCLC sub-types, namely adenocarcinoma (AC) and squamous cell carcinoma (SCC), respond differently to therapy. Whereas the link between cigarette smoke and lung cancer risk is well established, the relevance of non-canonical Wnt pathway up-regulation detected in SCC remains poorly understood. The present study was undertaken to investigate further the molecular events in canonical and non-canonical Wnt signalling during SCC development. A total of 20 SCC and AC samples with matched non-cancerous controls were obtained after surgery. TaqMan array analysis confirmed up-regulation of non-canonical Wnt5a and Wnt11 and identified down-regulation of canonical Wnt signalling in SCC samples. The molecular changes were tested in primary small airway epithelial cells (SAEC) and various lung cancer cell lines (e.g. A549, H157, etc). Our studies identified Wnt11 and Wnt5a as regulators of cadherin expression and potentiated relocation of b-catenin to the nucleus as an important step in decreased cellular adhesion. The presented data identifies additional details in the regulation of SCC that can aid identification of therapeutic drug targets in the future.
Genome medicine, 2015
The HHIP gene, encoding Hedgehog interacting protein, has been implicated in chronic obstructive pulmonary disease (COPD) by genome-wide association studies (GWAS), and our subsequent studies identified a functional upstream genetic variant that decreased HHIP transcription. However, little is known about how HHIP contributes to COPD pathogenesis. We exposed Hhip haploinsufficient mice (Hhip (+/-) ) to cigarette smoke (CS) for 6 months to model the biological consequences caused by CS in human COPD risk-allele carriers at the HHIP locus. Gene expression profiling in murine lungs was performed followed by an integrative network inference analysis, PANDA (Passing Attributes between Networks for Data Assimilation) analysis. We detected more severe airspace enlargement in Hhip (+/-) mice vs. wild-type littermates (Hhip (+/+) ) exposed to CS. Gene expression profiling in murine lungs suggested enhanced lymphocyte activation pathways in CS-exposed Hhip (+/-) vs. Hhip (+/+) mice, which was...
Hedgehog signaling pathway: the must, the maybe and the unknown
Journal of thoracic disease, 2013
Lung cancer treatment consists from the basic chemotherapeutic drugs (e.g., platinum analogues) and from pharmaceuticals targeting the different genome of lung tumors (e.g., tyrosine kinase inhibitors). During the last years pharmaceuticals targeting the tumor mutations are approved for first line treatment since they have provided increased overall survival in comparison to standard chemotherapy treatment. Furthermore, due to the increased interest in unrevealing the mechanisms of cell mutation, tumor evolution and tumor cell maintenance the hedgehog pathway has been elicited. Along with Notch and Wnt these three pathways are responsible for progenitor cell development and pulmonary organogenesis. Inhibitors of this pathway have been discovered and their application in the clinical practice is being investigated. However, further understanding of the mechanisms of regulation is needed.
Carcinogenesis, 2005
Although cigarette smoke has been epidemiologically associated with lung cancer in humans for many years, animal models of cigarette smoke-induced lung cancer have been lacking. This study demonstrated that life time whole body exposures of female B6C3F1 mice to mainstream cigarette smoke at 250 mg total particulate matter/m(3) for 6 h per day, 5 days a week induces marked increases in the incidence of focal alveolar hyperplasias, pulmonary adenomas, papillomas and adenocarcinomas. Cigarette smoke-exposed mice (n = 330) had a 10-fold increase in the incidence of hyperplastic lesions, and a 4.6-fold (adenomas and papillomas), 7.25-fold (adenocarcinomas) and 5-fold (metastatic pulmonary adenocarcinomas) increase in primary lung neoplasms compared with sham-exposed mice (n = 326). Activating point mutations in codon 12 of the K-ras gene were identified at a similar rate in tumors from sham-exposed mice (47%) and cigarette smoke-exposed mice (60%). The percentages of transversion and transition mutations were similar in both the groups. Hypermethylation of the death associated protein (DAP)-kinase and retinoic acid receptor (RAR)-beta gene promoters was detected in tumors from both sham- and cigarette smoke-exposed mice, with a tendency towards increased frequency of RAR-beta methylation in the tumors from the cigarette smoke-exposed mice. These results emphasize the importance of the activation of K-ras and silencing of DAP-kinase and RAR-beta in lung cancer development, and confirm the relevance of this mouse model for studying lung tumorigenesis.