Decreased lung tumorigenesis in mice genetically deficient in cytosolic phospholipase A2.

Epidemiological investigations suggest that chronic lung inflammation increases lung cancer risk. Pharmacologic and genetic evidence in mouse models indicates that lipid mediators released during pulmonary inflammation enhance lung tumor formation. Cytosolic phospholipase A2 (cPLA2) catalyzes arachidonic acid (AA) release from membrane phospholipids.

Pol iota is a candidate for the mouse pulmonary adenoma resistance 2 locus, a major modifier of chemically induced lung neoplasia.

In this study, we performed systematic candidate gene analyses of the Pulmonary adenoma resistance 2 locus. Differential gene expression in lung tissues and nucleotide polymorphisms in coding regions between A/J and BALB/cJ mice were examined using reverse transcription-PCR and direct sequencing. Although not all genes in the interval were analyzed at this moment due to the recent database updating, we have found that the Pol iota gene, encoding the DNA polymerase iota, contains 25 nucleotide polymorphisms in its coding region between A/J and BALB/cJ mice, resulting in a total of ten amino acid changes.

Cancer chemopreventive activity of a mixture of Chinese herbs (antitumor B) in mouse lung tumor models.

Antitumor B (ATB), also known as Zeng Sheng Ping, is a Chinese herbal mixture composed of six plants. Previously, clinical studies have shown a significant chemopreventive efficacy of ATB against human esophageal and lung cancers. In the present study, A/J mice harboring a dominant-negative p53 and/or heterozygous deletion of Ink4a/Arf and treated with benzo[a]pyrene were used to investigate the chemopreventive effects of ATB on chemically induced lung tumorigenesis.

CpG methylation in the Fhit regulatory region: relation to Fhit expression in murine tumors.

To determine if: (1) 5' CpG island methylation is related to Fhit inactivation; (2) there are tumor or carcinogen-specific methylation patterns, we examined 35 CpG sites in the promoter, exon and intron 1 of the mouse Fhit gene. In primary tumors of lung, urinary bladder and tongue, induced by different carcinogens, 15-35% of sites were methylated, with specific methylation patterns associated with each cancer type, suggesting cancer- or tissue-specific methylation patterns. The methylation patterns were associated with reduced Fhit expression, as determined by immunohistochemical analyses.

A chemically induced model for squamous cell carcinoma of the lung in mice: histopathology and strain susceptibility.

Lung cancer, primarily associated with tobacco use, is the leading cause of cancer morbidity and mortality in the United States. Squamous cell carcinoma (SCC) is one of the four major histological types of lung cancer. Although there are several established models for lung adenoma and adenocarcinomas, there is no well-established mouse model for lung SCC.

Carcinogen-specific targeting of chromosome 12 for loss of heterozygosity in mouse lung adenocarcinomas: implications for chromosome instability and tumor progression.

Genotoxic carcinogens exert their tumorigenic effects in part by inducing genomic instability. We recently showed that loss of heterozygosity (LOH) on chromosome 12 associates significantly with the induction of chromosome instability (CIN) by the likely human lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and vinyl carbamate (VC) during mouse lung carcinogenesis. Here, we demonstrate the carcinogen specificity of this event and its effect on lung tumor evolution.

CD24 is a genetic modifier for risk and progression of multiple sclerosis.

Multiple sclerosis (MS) is a chronic neurological disease of unknown etiology, but a genetic basis for the disease is undisputed. We have reported that CD24 is required for the pathogenicity of autoreactive T cells in experimental autoimmune encephalomyelitis, the mouse model of MS. Here we investigate the contribution of CD24 to MS by studying single-nucleotide polymorphism in the ORF among 242 MS patients and 207 population controls.

Molecular profiling of mouse lung tumors: association with tumor progression, lung development, and human lung adenocarcinomas.

We have performed oligonucleotide array analysis on various murine lung tissues [normal lungs, lung adenomas, and lung adenocarcinomas (ACs)] using Affymetrix U74Av2 GeneChips to examine the complex genetic changes occurring during lung carcinogenesis. Analysis yielded 20 novel genes differentially expressed in both lung adenomas and ACs versus normal lungs, including the tumor suppressor APC2 and the oncogene Ros 1. In addition, 50 genes were found to be differentially expressed in lung adenomas versus lung ACs, including the differentiation factor Hox C6, the oncogene Ets 2, and the Ras nuclear transport factor, nuclear transport factor 2.

Tnfa and Il-10 deficiencies have contrasting effects on lung tumor susceptibility: gender-dependent modulation of IL-10 haploinsufficiency.

Epidemiologic evidence suggests that pulmonary diseases with a prominent chronic inflammatory component elevate lung cancer risk. Genetic manipulations of mouse models of lung inflammation and tumorigenesis can be used to investigate this association. The genes encoding pro-inflammatory tumor necrosis factor-alpha (TNFalpha) and antiinflammatory IL-10 cytokines map within quantitative trait loci that regulate susceptibility to lung tumor development in mice; sensitive A/J and resistant C57BL/6J (B6) mice have different Tnfa and Il-10 alleles.

Positional cloning of the major quantitative trait locus underlying lung tumor susceptibility in mice.

Pulmonary adenoma susceptibility 1 (Pas1), located on chromosome 6, is the major locus affecting inherited predisposition to lung tumor development in mice. We have fine mapped the Pas1 locus to a region of approximately 0.5 megabases by using congenic strains of mice, constructed by placing the Pas1 region of chromosome 6 from A/J mice onto the genetic background of C57BL/6J mice.

A high performance test of differential gene expression for oligonucleotide arrays.

Logit-t employs a logit-transformation for normalization followed by statistical testing at the probe-level. Using four publicly-available datasets, together providing 2,710 known positive incidences of differential expression and 2,913,813 known negative incidences, performance of statistical tests were: Logit-t provided 75% positive-predictive value, compared with 5% for Affymetrix Microarray Suite 5, 6% for dChip perfect match (PM)-only, and 9% for Robust Multi-array Analysis at the p < 0.01 threshold.

RASSF1A promoter methylation and Kras2 mutations in non small cell lung cancer.

In the present studies, we investigated the correlation between RASSF1A promoter methylation status and Kras2 mutations in 65 primary non small cell lung cancer (NSCLC) including 33 adenocarcinomas, 12 large cell carcinomas, and 20 squamous cell carcinomas. Mutational analysis of Kras2 showed: 30% (10 of 33) of adenocarcinomas, 25% (3 of 12) of large cell carcinomas, and only 5% (1 of 20) of squamous cell carcinomas contained activated Kras2 mutation at codon 12 or 13. RASSF1A promoter region CpG island methylation was detected in adenocarcinomas (55%), large cell carcinomas (25%), and squamous cell carcinomas (25%).

Farnesyltransferase inhibitors are potent lung cancer chemopreventive agents in A/J mice with a dominant-negative p53 and/or heterozygous deletion of Ink4a/Arf.

Mutations in the Kras2 gene are seen in both human and mouse lung adenocarcinomas. The protein product (p21ras) encoded by the Kras2 gene must be post-translationally modified at a terminal CAAX motif in order to be biologically active. In this study, we systematically investigated the chemopreventive efficacy of two different farnesyltransferase inhibitors (FTIs): one is a peptidomimetic (FTI-276) and the other is an imidazole (L778-123).

Mice with alterations in both p53 and Ink4a/Arf display a striking increase in lung tumor multiplicity and progression: differential chemopreventive effect of budesonide in wild-type and mutant A/J mice.

p53 transgenic mice carrying a dominant negative mutation were crossed with Ink4A/Arf heterozygous-deficient mice to investigate whether there is a synergy between these two germ-line mutations in promoting carcinogen-induced lung tumor progression in mice. Mice with a p53 dominant negative mutation and Ink4A/Arf heterozygous deficiency exhibited >20-fold increase in tumor volume compared with approximately 4-fold increase in Ink4A/Arf heterozygous-deficient mice and a 9-fold increase in mice with only the p53 dominant negative mutation. The effect of Ink4A/Arf heterozygous deficiency on lung tumor progression occurred late in the carcinogenesis process (>30 weeks after carcinogen treatment).

Fine mapping and identification of candidate pulmonary adenoma susceptibility 1 genes using advanced intercross lines.

In the present study, we used newly developed F(11) generation mouse advanced intercross lines (AIL) to fine map Pas1-3 quantitative trait loci (QTL). The (A/J x C57BL/6) F(11) AIL mouse population was created by crossing lung tumor-resistant C57BL/6 mice with lung tumor-susceptible A/J mice. By selectively genotyping 30% of the population, we have confirmed the Pas1 QTL and narrowed it to an interval of approximately 1.

Differential gene expression in chemically induced mouse lung adenomas.

Because of similarities in histopathology and tumor progression stages between mouse and human lung adenocarcinomas, the mouse lung tumor model with lung adenomas as the endpoint has been used extensively to evaluate the efficacy of putative lung cancer chemopreventive agents. In this study, a competitive cDNA library screening (CCLS) was employed to determine changes in the expression of mRNA in chemically induced lung adenomas compared with paired normal lung tissues. A total of 2555 clones having altered expression in tumors were observed following competitive hybridization between normal lung and lung adenomas after primary screening of over 160,000 clones from a mouse lung cDNA library.

LOH of chromosome 12p correlates with Kras2 mutation in non-small cell lung cancer.

Previous observation has shown that the wild-type Kras2 allele is a suppressor of lung cancer in mice. Here we report that loss of heterozygosity (LOH) of chromosome 12p was detected in approximately 50% of human lung adenocarcinomas and large cell carcinomas, and Kras2 mutations were detected at codon 12 in approximately 40% of adenocarcinomas and large cell carcinomas. Interestingly, all of the lung adenocarcinomas and large cell carcinomas containing a Kras2 mutation exhibited allelic loss of the wild-type Kras2 allele when a correlation between LOH of the region on chromosome 12p and Kras2 mutation was made.

Cell proliferation, apoptosis, and expression of cyclin D1 and cyclin E as potential biomarkers in tamoxifen-treated mammary tumors.

Tamoxifen has been widely used for treatment, and more recently, for the prevention of breast cancer. Since breast carcinomas are composed of heterogeneous populations of estrogen receptor-positive (ER+) cells, we hypothesized that tamoxifen may suppress tumor growth by differentially affecting cell proliferation and apoptosis. ER+ mammary tumors were induced in Sprague-Dawley rats by N-methyl-N-nitrosourea (MNU) and when they became palpable, the animals were treated for 5, 10, or 20 days with tamoxifen, 1.

Molecular alterations and lung tumors in p53 mutant mice exposed to cigarette smoke.

Mutations and deletions in p53 are the most common genetic lesions in human cancer,and an extraordinarily high incidence of lung cancer occurs in smokers suffering from Li-Fraumeni syndrome, which is characterized by germ-line inactivation of one p53 allele. In contrast, p53 mutations are infrequent in lung tumors formed in A/J mice. Moreover, despite the dominant role of cigarette smoke in the epidemiology of human lung cancer, it is very difficult to reproduce the lung tumorigenicity of this complex mixture in animal models.

Carcinogenic induction directs the selection of allelic losses in mouse lung tumorigenesis.

Recent evidence suggests that genome-wide allelic imbalances are inducible by carcinogens and may occur as cells adapt to carcinogenic exposure during tumorigenesis. We investigated the role of carcinogenic exposure on global and selected loss of heterozygosity (LOH) during mouse lung adenocarcinogenesis. Tumor induction by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) or vinyl carbamate (VC) resulted in a significant overall increase in the number of chromosomes affected by LOH per tumor when compared with spontaneous lung tumors.

Linkage disequilibrium mapping of novel lung tumor susceptibility quantitative trait loci in mice.

Linkage disequilibrium (LD) has been used to map chromosomal regions regulating quantitative traits, also called quantitative trait loci (QTLs). With the increasing number of available mouse polymorphic genetic markers, LD can be estimated for the purpose of fine-mapping a given QTL or in the identification of novel QTLs. A whole-genome LD analysis was conducted for mapping mouse lung tumor susceptibility QTLs in 25 strains of mice with known susceptibility to lung cancer using 5638 genetic markers.

A strong candidate gene for the Papg1 locus on mouse chromosome 4 affecting lung tumor progression.

Lung cancer is the leading cause of cancer death among both men and women, accounting for more than 28% of all cancer deaths. In fact, more people die of lung cancer than of colon, breast, and prostate cancers combined. Although lung cancer is largely induced by smoking, there is strong evidence for genetic susceptibility and gene-environment interactions in the development of lung cancer.

Differentially expressed genes associated with mouse lung tumor progression.

To detect altered gene expression associated with mouse lung tumor progression, we compared the gene expression profile of lung adenocarcinomas with that of lung adenomas and normal lungs. Autoradiographic analysis showed that among the 588 genes surveyed, 152 genes were detected and the remaining 436 genes did not give any signals. A gene-specific semiquantitative reverse transcription polymerase chain reaction method was used to confirm the expression profile.

p53 transgenic mice are highly susceptible to 1, 2-dimethylhydrazine-induced uterine sarcomas.

p53 Transgenic mice were crossed with C57BL/6J mice to investigate whether a germ-line mutation in the p53 gene predisposes for tumorigenesis in mice. (C57BL/6J x UL53-3) F(1) mice were treated with 1,2-dimethylhydrazine (DMH), a colon carcinogen. The presence of a mutant p53 led to an increased incidence or multiplicity of uterine sarcomas, colon carcinomas, lung adenomas, and hepatomas in DMH-treated mice.