Haploinsufficiency of the cdc2l gene contributes to skin cancer development in mice

The Cdc2L gene encodes for the cyclin-dependent kinase 11 (CDK11) protein. Loss of one allele of Cdc2L and reduced CDK11 expression has been observed in several cancers, implicating its association with carcinogenesis. To directly investigate the role of CDK11 in carcinogenesis, we first generated cdc2l haploinsufficient mice by gene trap technology and then studied the susceptibility of these gene-trapped (cdc2l(GT)) mice to chemical-mediated skin carcinogenesis in the 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced two-stage skin carcinogenesis model. Wild-type and cdc2l(GT) mice were subjected to a single topical application of initiation by DMBA and promotion twice a week for 19 weeks with TPA. At 19 weeks, 70% of the cdc2l(GT) mice and 60% of the cdc2l+/+ mice developed benign papillomas. However, there was an overall 3-fold increase in the average number of tumors per mouse observed in cdc2l(GT) mice as compared with cdc2l+/+ mice. There was also an increased frequency of larger papillomas in cdc2l(GT) mice. By using the polymerase chain reaction-restriction fragment length polymorphism assay, we found A to T transversion mutations at the 61st codon of H-ras gene in the papilloma tissue of both cdc2l(GT) mice and cdc2l+/+ mice. Ki-67 staining revealed increased proliferation in the papillomas of cdc2l(GT) (77.75%) as compared with cdc2l+/+ (30.84%) tumors. These studies are the first to show that loss of one allele of cdc2l gene, encoding CDK11, facilitates DMBA/TPA-induced skin carcinogenesis in vivo.

Angioma serpiginosum with oesophageal papillomatosis is an X-linked dominant condition that maps to Xp11.3–Xq12

We report on a four-generation family with localized subepidermal telangiectasias following Blaschko's lines (angioma serpiginosum). The vascular streaks are present at birth and progress slowly thereafter. In several family members papillomatosis of the entire oesophagus was found to be part of the condition. Mild nail and hair dystrophy added to the resemblance of Goltz-Gorlin syndrome (focal dermal hypoplasia), suggesting that the present condition could be a mild variant. All affected family members are females, there is no increased miscarriage rate, and X-inactivation in affected females is highly skewed, compatible with X-linked dominant inheritance with very early in utero lethality in males. In the family, 11 informative meioses were available to study the segregation of X-chromosome markers. Significant linkage (LOD score 3.31) was found to a region flanked by markers DXS8026 and DXS106 (44-67 Mb from Xpter) that includes the centromere.

[Clonality of the peripheral papilloma and cancerous cells of breast]

OBJECTIVE

To study the clonality status of peripheral papilloma (peri-MP), ductal carcinoma in situ (DCIS), and normal tissue of the breast using an assay based on inactivation mosaicism of the length-polymorphic X-chromosomes at the androgen receptor (AR) locus and to explore a reliable way to distinguish the benign and malignant (or pre-malignant) cases judged morphologically.

METHODS

Specimens of breast tissues were obtained from 26 cases of peri-PM, 25 cases of peri-PM with atypical ductal hyperplasia (ADH), and 27 cases pf DCIS, 16 cases of developed canceration, and 20 normal women. DNA was extracted and amplified via nested-PCR with or without previous digestion by the methylation-sensitive restriction endonuclease Hha I. The products were resolved on denaturing polyacrylamide gels and visualized through silver staining. The clonality of these samples was analyzed by showing the lanes.

RESULTS

Loss of polymorphism at the AR locus was found in all the cases with DCIS and in 10 cases (10/25, 40.0%) of peri-PM with ADH, indicating the monoclonality of the tumor. Twenty-four cases (92.3%) of the 26 cases with peri-PM and the 20 specimens of normal tissue were shown to be polyclonal. In the 16 cases of developed canceration identical X chromosome inactivation (monoclonal alterations) was observed in the cancer focus, parts of peri-PM with ADH, and the part of DCIS.

CONCLUSION

Normal breast tissue and peri-PM show polyclonality and the peri-PM with ADH shows monoclonality. Clonality analysis may be a useful modality to screen high-risk cases from precancerous lesions or to distinguish between the benign hyperplasia and early carcinoma.

Homozygous K5Cre transgenic mice have wavy hair and accelerated malignant progression in a murine model of skin carcinogenesis

Mice with conditional gene deletions have been extremely valuable in allowing investigators to study the genes of interest in a tissue-specific manner. The Cre-loxP recombination system provides a powerful tool to produce targeted rearrangements of particular genes. The keratin 5-Cre recombinase (K5Cre) transgenic mouse line has been used to generate skin specific gene deletions. We found that the K5Cre mice display a unique phenotype when bred to homozygosity. The K5Cre(+/+) mice have a wavy hair coat and curly whiskers. Histologically, the hair follicles appear disoriented. Over time, the K5Cre(+/+) mice develop patches of alopecia. These mice are also runted when compared to wild-type controls. Fostering the K5Cre(+/+) pups to wild-type mothers results in normal weight gain, suggesting a maternal defect in milk production. When the K5Cre(+/+) mammary glands were examined, we not only found a significant decrease in the number of mammary branches in the virgin females, but also a greater number of quiescent alveoli units in the lactating glands. When the K5Cre(+/+) mice were bred to v-Ha-ras (Tg . AC) transgenic mice, the resulting Tg . AC(+/-) K5Cre(+/+) offspring were utilized in a chemically induced skin carcinogenesis model. The mice were treated with 2.5 microg of 12-O-tetradecanoylphorbol-13-acetate (TPA) weekly for 10 wk. No difference was observed in the time to onset of papilloma formation, the number of papillomas and the average papilloma volume between the Tg . AC(+/-) K5Cre(+/+) mice and their corresponding controls. Surprisingly, however, the K5Cre(+/+) papillomas displayed an accelerated tendency to malignant progression; in addition, the frequency of malignant transformation of the papillomas is significantly enhanced. Although the K5Cre(+/+) mice resemble waved-1 and -2 mutants, the molecular basis for the K5Cre(+/+) phenotype is probably different. In conclusion, we discovered a unique phenotype associated with the K5Cre(+/+) transgenic line.

Selective decrease in the DNA base excision repair pathway in squamous cell cancer of the esophagus

OBJECTIVES

Oxidative damage can lead to a highly mutagenic 8-oxoguanine lesion, which mispairs with adenosine residues, leading to G:C-->T:A transversions. In mammalian cells 8-oxoguanine glycosylase initiates the DNA base excision repair pathway to repair the 8-oxoguanine lesion. To date, there is no information regarding oxidative DNA damage and repair pathways in esophageal cancer. Therefore we designed the current study to demonstrate the DNA damage and repair pathways in esophageal cancer by expression of 8-oxoguanine glycosylase in reflux-induced and mutagen (methyl-n-amyl nitrosamine)-induced DNA damage and apoptosis in esophageal tumors.

METHODS

Gastroduodenal reflux was surgically created in male Sprague Dawley rats (n = 120). Half of the animals received methyl-n-amyl nitrosamine. Animals not undergoing operations served as control animals (n = 10). The experiment concluded 30 weeks postoperatively. Immunohistochemistry for 8-oxoguanine and 8-oxoguanine glycosylase was assessed by 2 independent observers. Protein expression was assessed by using the Western blot method.

RESULTS

There was significantly more DNA damage in both adenocarcinoma (n = 15) and squamous cell carcinoma (n = 19), as exemplified by positive 8-oxoguanine expression compared with that seen in control animals (P < .05). 8-Oxoguanine glycosylase was several folds upregulated in adenocarcinoma (P < .05), but there was significantly decreased expression in squamous cell carcinoma (P < .01). The apoptosis was assessed as caspase-dependent and caspase-independent pathways, and both were active and correlated well with 8-oxoguanine expression.

CONCLUSION

These results demonstrate the selective decrease in the DNA base excision repair pathway in combined reflux and methyl-n-amyl nitrosamine-induced squamous cell cancer of the esophagus.

Loss of MAL expression in precancerous lesions of the esophagus

BACKGROUND

We have identified a novel function of MAL (T-cell differentiation-related gene) as a candidate suppressor gene in esophageal cancer. As the role of MAL expression in esophageal carcinogenesis is as yet undetermined, MAL expression in a rat multi-step carcinogenic model and in precancerous lesions of the human esophagus was investigated. Microarray analysis between MAL-transfectant and control cells was also carried out to clarify how MAL confers its anti-tumor effects.

MATERIALS AND METHODS

(1) In the rat model, MAL expression levels in laser microdissected normal esophageal epithelium, dysplastic tissues and carcinoma tissues were examined by reverse transcription (RT)-PCR. (2) Immunostaining with MAL antibody was performed in 10 dysplastic lesions adjacent to cancer in six cases of esophageal cancer. (3) We established a MAL transfectant using a Tet-off vector in esophageal cancer cells and performed microarray analysis under MAL-positive and MAL-negative conditions.

RESULTS

(1) In the rat model, MAL mRNA expression was observed only in the normal samples. (2) MAL expression was observed distinctively in differentiated or keratinized normal tissues and was not observed in either dysplastic lesions or carcinoma tissue. (3) Up-regulated genes in MAL-positive cells included keratin 18 (transfectant/control = 2.94) and keratin 10 (t/c = 2.82).

CONCLUSION

MAL expression was lost in dysplastic lesions of the rat carcinoma model as well as the human esophagus. The up-regulated keratins revealed by microarray analysis and the strong staining of the differentiated normal tissues in immunohistochemical study support the role of MAL as a regulator of differentiation in esophageal epithelium.

HPV genotyping and HLA II analysis in a pedigree study of pediatric RRP: preliminary results

OBJECTIVE

This preliminary pedigree study aims at the evaluation of HPV infection and HLA class II alleles as predictive markers in pediatric RRP.

METHODS

We investigated for HPV genotyping and HLA class II polymorphisms all the components of family nucleus where we detected a child born to an HPV infected mother and suffering from RRP.

RESULTS

HPV 11 was detected both in the laryngeal biopsies of two of the three affected babies and in the cervical smear of their mothers. The third child was positive for HPV 6 while his mother harboured a double HPV 6-16 infection. In one family, the HLA-DQB1*0501 allele exerted its protective role. The HLA-DQB1*0301 allele, commonly associated to a high grade of cervical neoplasia and HPV infection, was present in homozygous in one mother and her child. The same allele was found, though in a heterozygous form, in the third patient too.

CONCLUSION

Our report is the first attempt to use the pedigree study for the evaluation of HLA class II alleles and HPV infection related to pediatric RRP. This approach could identify genetic markers that may influence disease predisposition and the severity of HPV infection.

Interleukin-12-deficient mice are at greater risk of UV radiation-induced skin tumors and malignant transformation of papillomas to carcinomas

Solar UV radiation-induced immunosuppression is a risk factor for nonmelanoma skin cancer. Interleukin (IL)-12 has been shown to possess antitumor activity and inhibit the immunosuppressive effects of UV radiation in mice. In this study, we generated IL-12 knockout (KO) mice on a C3H/HeN background to characterize the role of IL-12 in photocarcinogenesis. After exposure of the mice to UVB (180 mJ/cm2) radiation thrice a week for 35 weeks, the development of UV-induced tumors was more rapid and the tumor multiplicity and tumor size were significantly higher in IL-12 KO mice than their wild-type (WT) counterparts (P < 0.05-0.001). Moreover, the malignant transformation of UVB-induced papillomas to carcinomas was higher in IL-12 KO mice in terms of carcinoma incidence (55%, P < 0.001), carcinoma multiplicity (77%, P < 0.001), and carcinoma size (81%, P < 0.001). As IL-12 has the ability to repair UV-induced DNA damage, we determined this effect in our in vivo IL-12 KO mouse model. We found that UVB-induced DNA damage in the form of cyclobutane pyrimidine dimers was removed or repaired more rapidly in WT mice than IL-12 KO mice. Similarly, the UVB-induced sunburn cell formation is primarily a consequence of DNA damage. It was observed that UVB-induced sunburn cells were repaired rapidly in WT mice compared with IL-12 KO mice. The rapid removal or repair of UV-induced cyclobutane pyrimidine dimers or sunburn cells will result in reduced risk of photocarcinogenesis. Taken together, our data show that IL-12 deficiency is associated with the greater risk of photocarcinogenesis in mice, and this may be due to reduction in damaged DNA repair ability.

Genetic analysis of myc and telomerase interactions in vivo

Myc is a transcription factor with pleiotropic effects on tumorigenesis which are likely to be mediated by its target genes. A known Myc transcriptional target is the catalytic subunit of telomerase, Tert. However, the contribution of Tert activation to Myc-induced tumorigenesis in vivo remains unknown. In this study, we addressed the role of telomerase in Myc-induced skin papillomatosis by using compound mice with a switchable Myc gene, Inv-MycERTAM mice, in combination with either telomerase deficiency (Terc-/-) or telomerase overexpression (K5-mTert) in the skin. We first demonstrated that Myc activates telomerase in the skin. With Inv-MycERTAM x Terc-/- mice, we further showed that this telomerase activation is partially required to elicit a full hyperplastic Myc-induced response. The presence of critically short telomeres in late-generation Inv-MycERTAM x Terc-/- mice further reduced the skin lesion induced by Myc. On the other hand, telomerase overexpression in the skin of K5-mTert mice augments Myc-induced hyperplasia in the absence of changes in telomere length, suggesting a direct role of telomerase in the Myc protumorigenic response. Taken together, these results highlight telomerase as a mediator of Myc-induced papillomatosis and suggest telomerase as a putative therapeutic target for Myc-dependent lesions.

Four mutations in Epidermodysplasia verruciformis 1 (EVER1) gene are not contributors to susceptibility in RRP

OBJECTIVE

Epidermodysplasia verruciformis is a skin disease characterized by abnormal susceptibility to human papilloma viruses. Recently four mutations in the Epidermodysplasia verruciformis 1 gene (EVER1, also known as TMC6) have been associated with the disease. Because of the phenotypic similarity between Epidermodysplasia verruciformis and recurrent respiratory papillomatosis, we decided to investigate whether any of these mutations accounts for the susceptibility to human papilloma viruses in subjects with recurrent respiratory papillomatosis (RRP).

METHODS

Allele-specific PCR and restriction fragment length polymorphisms (RFLPs) were employed for genotyping a cohort of 101 patients with recurrent respiratory papillomatosis.

RESULTS

None of these four mutations were found in the studied subjects.

CONCLUSION

The absence of these mutations in RRP patients might indicate that EVER 1 alleles are not associated with susceptibility to RRP, or that other, as yet unidentified, mutations in the Epidermodysplasia verruciformis 1 gene, might account for the susceptibility to RRP.

Elevated prostaglandin E2 level via cPLA2--COX-2--mPGES-1 pathway involved in bladder carcinogenesis induced by terephthalic acid-calculi in Wistar rats

To investigate the prostaglandin E2 (PGE2) biosynthetic mechanism in bladder carcinogenesis, we established Wistar rat model of bladder papilloma and transitional cell carcinoma (TCC) induced by 5% terephthalic acid (TPA) treatment. Then, the mRNA level of cytosolic phospholipase A2 (cPLA2), cyclooxygenases (COX)-1 and -2, membrane-bound PGE2 synthases (mPGES)-1 and -2 was detected using reverse transcription polymerase chain reaction (RT-PCR). Immunoblotting was applied to detect the expression of COX-2 protein. Proliferating cell nuclear antigen (PCNA) was determined by immunohistochemistry. In addition, the level of PGE2 was measured by radioimmunoassay (RIA). Bladder papilloma (100%, 8/8) was examined in rats after 24-week treatment, and bladder TCC (80%, 16/20) was found after 48-week treatment. Histopathological changes were not found in control group rats. The incidence of bladder papilloma and TCC in test group was significantly higher than that in control group (P<0.01). The mRNA levels of cPLA2, COX-2 and mPGES-1 in the bladder papilloma and TCC were significantly higher than those in normal bladder (P<0.01), while the mRNA levels of COX-1 and mPGES-2 in TCC were unchanged compared with normal bladder. Bladder TCC exhibited a substantial expression of COX-2 protein. On the contrary, normal bladder tissue barely expresses COX-2 protein. PCNA labeling index (LI) and the level of PGE2 in bladder papilloma are much higher than those in normal bladder (P<0.01), but lower than those in bladder TCC (P<0.05). In conclusion, increasing PGE2 level via cPLA2--COX-2--mPGES-1 pathway may play an important role in rat bladder carcinogenesis. PGE2 may be a biomarker for the development of bladder TCC. cPLA2 and mPGES-1 may be targets for development of novel chemoprevention strategies for bladder TCC.

Molecular and virological studies on a rare case of biliary papillomatosis

In a recurrence of a rare case of biliary papillomatosis, a disease that often becomes malignant, the presence of human papillomavirus (HPV), Cytomegalovirus (CMV) and Epstein-Barr virus (EBV), as well as DNA ploidy and markers of proliferation and invasion, were examined. No such viruses were identified by polymerase chain reactions. Moreover, markers of invasion, such as laminin, and of proliferation, MIB1 and cyclin A, were absent or at normal levels despite progressive superficial growth of the tumour. The tumour was aneuploid, but the p53-p21 tumour growth suppressor system was not mutated. It was concluded that the presented case of tumour relapse, despite an anamnesis of seven years and its expanding but non-invasive growth, did not contain the viruses that were examined for, and had not become malignant.

Mutation of p53 in skin papilloma and tubular breast adenoma of albino mice

OBJECTIVE

To determine the mutation of p53 in chemically induced carcinogenesis on albino mice in skin papilloma and tubular adenoma breast by immunohistochemistry.

DESIGN

An experimental study.

PLACE AND DURATION OF STUDY

The animal house of Postgraduate Medical Institute and Pathology Department of King Edward Medical College University, Lahore, for the duration of 20 weeks, from 15 February, 2004 to 15 July, 2004.

SUBJECTS AND METHODS

Twenty five albino mice (male and female) were selected for a study on chemical carcinogenesis. These animals were divided into five groups (A-E), five animals in each. DMBA (Dimethylebenz[a] Anthracene) and TPA (Tetradecanoyl-phorbal-13-Acetic Acid) [chemical carcinogens] were given to produce the tumors and mutation of p53 expression was evaluated on the tumors appearing during this period of carcinogenesis. Squamous cell papillomas and tubular adenoma breast were selected for this study.

RESULTS

All the papillomas showed faint reactivity for immunomarker p53, while tubular adenomas were nonreactive.

CONCLUSION

The results of this study show that p-53 is a marker for premalignant lesions and helps in selecting patients for constant monitoring, upon the clinical verification of these results.

PTEN loss promotes rasHa-mediated papillomatogenesis via dual up-regulation of AKT activity and cell cycle deregulation but malignant conversion proceeds via PTEN-associated pathways

PTEN tumor suppressor gene failure in ras(Ha)-activated skin carcinogenesis was investigated by mating exon 5 floxed-PTEN (Delta5PTEN) mice to HK1.ras mice that expressed a RU486-inducible cre recombinase (K14.creP). PTEN inactivation in K14.cre/PTEN(flx/flx) keratinocytes resulted in epidermal hyperplasia/hyperkeratosis and novel 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted papillomas, whereas HK1.ras/K14.cre/PTEN(flx/flx) cohorts displayed a rapid onset of papillomatogenesis due to a synergism of increased AKT activity and extracellular signal-regulated kinase (ERK) elevation. High 5-bromo-4-deoxyuridine labeling in Delta5PTEN papillomas showed that a second promotion mechanism centered on failures in cell cycle control. Elevated cyclin D1 was associated with both HK1.ras/ERK- and Delta5PTEN-mediated AKT signaling, whereas cyclin E2 overexpression seemed dependent on PTEN loss. Spontaneous HK1.ras/Delta5PTEN malignant conversion was rare, whereas TPA promotion resulted in conversion with high frequency. On comparison with all previous HK1.ras carcinomas, such TPA-induced carcinomas expressed atypical retention of keratin K1 and lack of K13, a unique marker profile exhibited by TPA-induced K14.cre/PTEN(flx/flx) papillomas that also lacked endogenous c-ras(Ha) activation. Moreover, in all PTEN-null tumors, levels of ras(Ha)-associated total ERK protein became reduced, whereas phosphorylated ERK and cyclin D1 were lowered in late-stage papillomas returning to elevated levels, alongside increased cyclin E2 expression, in TPA-derived carcinomas. Thus, during early papillomatogenesis, PTEN loss promotes ras(Ha) initiation via elevation of AKT activity and synergistic failures in cyclin regulation. However, in progression, reduced ras(Ha)-associated ERK protein and activity, increased Delta5PTEN-associated cyclin E2 expression, and unique K1/K13 profiles following TPA treatment suggest that PTEN loss, rather than ras(Ha) activation, gives rise to a population of cells with greater malignant potential.

Association of gene expression with sequential proliferation, differentiation and tumor formation in murine skin

Differential gene expression in two established initiation and promotion skin carcinogenesis models during promotion and tumor formation was determined by microarray technology with the purpose of distinguishing the genes more associated with neoplastic transformation from those linked with proliferation and differentiation. The first model utilized dimethylbenz[a]anthracene initiation and 12-O-tetradecanoylphorbol 13-acetate (TPA) promotion in the FVB/N mouse, and the second TPA promotion of the Tg.Ac mouse, which is endogenously initiated by virtue of an activated Ha-ras transgene. Comparison of gene expression profiles across the two models identified genes whose altered expression was associated with papilloma formation rather than TPA-induced proliferation and differentiation. DMBA suppressed TPA-induced differentiation which allowed identification of those genes associated more specifically with differentiation rather than proliferation. EASE (Expression Analysis Systemic Explorer) indicated a correlation between muscle-associated genes and skin differentiation, whereas genes involved with protein biosynthesis were strongly correlated with proliferation. For verification the altered expression of selected genes were confirmed by RT-PCR; Carbonic anhydrase 2, Thioredoxin 1 and Glutathione S-transferase omega 1 associated with papilloma formation and Enolase 3, Cystatin beta and Filaggrin associated with TPA-induced proliferation and differentiation. In situ analysis located the papillomas Glutathione S-transferase omega 1 expression to the proliferating areas of the papillomas. Thus we have identified profiles of differential gene expression associated with the tumorigenesis and promotion stages for skin carcinogenesis in the mouse.

Methylation of the O6-methylguanine-DNA methyltransferase promoter suppresses expression in mouse skin tumors and varies with the tumor induction protocol

Hypermethylation of CpG sites within the promoter region of the O6-methylguanine-DNA methyltransferase (MGMT) gene occurs frequently in human cancer, preventing both MGMT expression and repair of alkylation damage. To assess the role of MGMT in the development of mouse skin tumors induced by initiation-promotion protocols, methylation of the MGMT promoter was examined in tumor DNA using methylation-specific PCR. To determine whether MGMT promoter methylation was affected by the tumor induction protocol, tumors were initiated by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or 7,12-dimethylbenz[a]anthracene (DMBA) and promoted by 12-O-tetradecanoylphorbol-13-acetate (TPA) or mezerein. Although the MGMT promoter was not methylated in normal skin, promoter methylation was found in 56 of 136 papillomas (41.2%) and in 19 of 37 squamous cell carcinomas (51.4%). When methylation of the MGMT promoter was compared in the 4 treatment groups, hypermethylation was found more frequently in tumors initiated by DMBA and promoted by mezerein, a protocol associated with a high frequency of malignant conversion. Methylation was found in some tumors as early as 5 weeks after initiation, but the methylation frequency increased with time. MGMT promoter methylation reduced MGMT expression as determined by immunohistochemistry. Although MGMT promoter methylation was not generally correlated with ras mutations, the frequency of MGMT methylation was higher in MNNG-initiated, mezerein-promoted papillomas with mutations in Ha-ras compared to papillomas with Ki-ras. Methylation of the MGMT promoter, associated with reduced MGMT expression, is found in nearly half of mouse skin tumors, but varies with both the tumor initiator and tumor promoter, and may be a key step in the progression from papillomas to carcinomas.

Identification of genes and gene ontology processes critical to skin papilloma development in Tg.AC transgenic mice

This study analyzes gene expression associated with papilloma development in Tg.AC v-Ha-ras transgenic mice and identifies novel genes and biological processes that may be critical to skin carcinogenesis in these mice. Epidermal abrasion was used to synchronously induce epidermal regeneration in FVB/N wild type and transgenic Tg.AC mice. Skin papillomagenesis was uniquely induced in Tg.AC mice, and gene expression profiling was carried out using a 22,000 element mouse DNA microarray. Histological analysis showed that papillomas developed at a high rate by d 30 after abrasion in transgenic animals, while no papilloma developed in wild type mice. Transgene-specific differentially expressed genes were identified at d 30 postabrasion and these genes were annotated using EASE software and literature mining. Annotated and non-annotated genes associated with papilloma development were identified and clustering analysis revealed groups of genes that are coordinately expressed. A number of genes associated with differentiation and development were also physically clustered on mouse chromosome 16, including 16B3 that contains several Stefins and stefin-like genes, and 16A1 containing a number of keratin associated protein genes. Additional analyses presented here yield novel insights into the genes and processes involved in papilloma development in Tg.AC mice.

Topical application of representative multifunctional acrylates produced proliferative and inflammatory lesions in F344/N rats and B6C3F1 mice, and squamous cell neoplasms in Tg.AC mice

Widespread human exposure to multifunctional acrylates is of concern, due to their inherent reactivity and irritating properties. Trimethylolpropane triacrylate (TMPTA) and pentaerythritol triacrylate (PETA) are industrially important representatives of multifunctional acrylates. The current studies characterized the toxicity of 3-month topical administration of technical grade TMPTA and PETA in F344/N rats and B6C3F1 mice, and evaluated the carcinogenic potential of TMPTA and PETA in hemizygous Tg.AC (v-Ha-ras) transgenic mice. Administration of 0.75, 1.5, 3, 6, and 12 mg/kg TMPTA and PETA for 3 months resulted in hyperplastic, degenerative, and necrotic lesions, accompanied by chronic inflammation of the skin, with severities generally increasing with dose. Lesions were slightly more severe in rats, when compared with mice, and illustrate the irritant potential of TMPTA and PETA. A similar dosage regimen was used for the 6-month study with Tg.AC mice. Topical application of TMPTA and PETA to Tg.AC mice showed dose-dependent increases in squamous cell papillomas at the site of application, with decreases in the latency of their appearance in mice receiving 3 mg/kg or greater. Papillomas, the reporter phenotype in Tg.AC mice, were accompanied by a few squamous cell carcinomas, along with hyperplastic and inflammatory lesions. Although chronic inflammation might have contributed to the development of the skin lesions, the dose-related nature of the induction of the skin papillomas in Tg.AC mice by TMPTA and PETA may reflect a potential for carcinogenicity.

Microarray analysis of differentially expressed genes of primary tumors in the canine central nervous system

The pathophysiologic similarities of many human and canine cancers support the role of the domestic dog as a model for brain tumor research. Here we report the construction of a custom canine brain-specific cDNA microarray and the analysis of gene expression patterns of several different types of canine brain tumor. The microarray contained 4000 clones from a canine brain specific cDNA library including 2161 clones that matched known genes or expressed sequence tags (ESTs) and 25 cancer-related genes. Our study included 16 brain tumors (seven meningiomas, five glial tumors, two ependymomas, and two choroid plexus papillomas) from a variety of different dog breeds. We identified several genes previously found to be differentially expressed in human brain tumors. This suggests that human and canine brain tumors share a common pathogenesis. In addition, we also found differentially expressed genes unique to either meningiomas or the glial tumors. This report represents the first global gene expression analysis of different types of canine brain tumors by cDNA microarrays and might aid in the identification of potential candidate genes involved in tumor formation and progression.

Dual FISH analysis of benign and malignant tumors of the salivary glands and paranasal sinuses

To date, the underlying genomic changes in benign and malignant tumors of salivary-gland and paranasal-sinus origin are poorly understood. This is due in part to the low incidence of these tumors and the enormous histological variety of tumors within this head and neck region. We examined 58 of these tumors (14 adenoid cystic carcinomas, 9 adenocarcinomas, 5 cylindrical carcinomas, 11 pleomorphic adenomas, and 19 inverted papillomas) by dual fluorescence in situ hybridization (FISH) with centromere-specific probes on six chromosomes (3, 7, 9, 11, 17, and 18) for numerical changes. In adenoid cystic carcinomas, monosomy of chromosome 17 and polysomy of chromosomes 3, 9 and 11 were most frequently encountered. In adenocarcinomas, monosomy of chromosome 17 and polysomy of chromosomes 7 and 11 were most frequent. In cylindrical cell carcinomas, polysomy of chromosomes 7, 9, 11 and 17 was present in the majority of tumors. Disomy is rare, even in benign tumors. Polysomy is more frequent in malignant tumors than in benign. Tetrasomy is found almost only in malignant tumors. In summary, the occurrence of polysomy might reflect a step towards malignancy in tumors of the salivary glands and paranasal mucosa. Polysomy of chromosome 11 could be defined as typical for all investigated histological types of malignant tumor in this region of the head and neck.

Induction of Invasive Mouse Skin Carcinomas in Transgenic Mice with Mutations in Both H-ras and p53

Synergistic interaction between H-ras and p53 were systematically examined during skin tumorigenesis. Concurrent expression of an activated H-ras gene and a mutant p53 gene was accomplished by crossing p53(Val135/wt) mice with TG.AC mice. Topical application to wild-type mice with benzo(a)pyrene (BaP) alone produced approximately 26% skin tumor incidence, whereas BaP treatment of p53(wt/wt)Hras(TG.AC/wt), p53(Val135/wt)Hras(wt/wt), and p53(Val135/wt)Hras(TG.AC/wt) mice produced a 75%, 77%, and 100% incidence of skin tumors, respectively. An average of 0.33 tumor per mouse was observed in wild-type (p53(wt/wt)Hras(wt/wt)) mice, whereas approximately 1.54, 1.96, and 3.08 tumors per mouse were seen in BaP-treated p53(wt/wt)Hras(TG.AC/wt), p53(Val135/wt)Hras(wt/wt), and p53(Val135/wt)Hras(TG.AC/wt) mice, respectively. The effects on total tumor volume were even more striking with 7-, 48-, and 588-fold increases in tumor volume compared with wild-type (p53(wt/wt)Hras(wt/wt)) in p53(wt/wt)Hras(TG.AC/wt), p53(Val135/wt)Hras(wt/wt), and p53(Val135/wt)Hras(TG.AC/wt) mice, respectively. Histopathologically, all tumors from p53(wt/wt)Hras(wt/wt) mice were either papillomas or well-differentiated squamous cell carcinomas, whereas the tumors in p53(wt/wt)Hras(TG.AC/wt), p53(Val135/wt)Hras(wt/wt), and p53(Val135/wt)Hras(TG.AC/wt) mice were principally squamous cell carcinomas with varying degree of invasiveness. Particularly, tumors in p53(Val135/wt)Hras(TG.AC/wt) mice exhibited the most rapid growth and the extreme form of tumor invasion. Microarray analysis revealed that dominant-negative p53 (Val135) and activated H-ras affected several cellular processes involved in tumorigenesis possibly through its effects on apoptosis, cell cycle arrest, and Ras-mitogen-activated protein kinase pathways. The present study provides the first in vivo evidence that a germ line p53 mutation and activated H-ras act synergistically to profoundly enhance tumor progression.

Mice lacking the p53/p63 target gene Perp are resistant to papilloma development

Perp is a target of the p53 tumor suppressor involved in the DNA damage-induced apoptosis pathway. In addition, Perp is a target of the p53-related transcription factor p63 during skin development, where it participates in cell-cell adhesion mediated through desmosomes. Here we test the role of Perp in tumorigenesis in a two-step skin carcinogenesis model system. We find that mice lacking Perp in the skin are resistant to papilloma development, displaying fewer and smaller papillomas than wild-type mice. Proliferation levels, apoptotic indices and differentiation patterns are similar in the skin of treated Perp-deficient and wild-type mice. Instead, impaired adhesion through aberrant desmosome assembly may explain the diminished tumor development in the absence of Perp. These studies indicate that in certain contexts, Perp is required for efficient carcinogenesis and suggest a role for intact cell-cell adhesion in supporting tumor development in these settings.

Mechanisms of SEPA 0009-induced tumorigenesis in v-rasHa transgenic Tg.AC mice

Genetically engineered mouse models with altered oncogene or tumor suppressor gene activity have been utilized recently for carcinogen identification. The v-rasHa transgenic Tg.AC mouse, with its enhanced susceptibility to skin tumorigenesis, is thought to be well suited for examining the carcinogenicity of topically applied agents. Tg.AC mice were used to examine the carcinogenicity of SEPA 0009, a rationally designed organic molecule designed to enhance drug penetration through the skin. Fifty mg SEPA 0009/kg body weight, 1500 mg SEPA 0009/kg body weight, or the vehicle alone was applied daily to the skin of Tg.AC mice. Nontransgenic FVB/N mice were also treated with the vehicle alone or 1500 mg SEPA 0009. Daily application of a high-dose of SEPA 0009 caused severe and chronic irritation by 1 week that was maintained throughout the experiment. The irritation was accompanied by increased proliferation, increased apoptosis, and expression of the wound-associated keratin 6. High-dose SEPA 0009 induced squamous papillomas in Tg.AC, but not in nontransgenic mice, by 6 weeks. In mice treated with the high dose SEPA 0009, transgene expression was detected in papillomas at week 9, well after the onset of skin irritation and hyperplasia. In contrast, low-dose SEPA 0009 was not irritating to the skin and did not induce papillomas. Thus, SEPA 0009-induced tumorigenesis was associated with chronic and severe irritation. We propose that SEPA 0009-induced tumorigenesis in Tg.AC mice proceeds through an indirect mechanism that is secondary to cutaneous irritation.

Reduced excision repair cross-complementing 1 expression associates with enhanced papilloma formation and fibroblast transformation after genetic disruption of secreted protein acidic and rich in cysteine

SPARC (secreted protein acidic and rich in cysteine)/ osteonectin/BM-40 is a matricellular protein implicated in development, cell transformation and tumorigenesis. We have examined the role of SPARC in cell transformation induced chemically with 7,12-dimethylbenz[a]anthracene (DMBA) and 12-tetradecanoylphorbol-13-acetate (TPA) in embryonic fibroblasts and in the skin of mice. Embryonic fibroblasts from SPARCnull mice showed increases in cell proliferation, enhanced sensitivity to DMBA and a higher number of DMBA/TPA-induced transformation foci. The number of DMBA-DNA adducts was 9 times higher in SPARCnull fibroblasts and their stability was lower than wild-type fibroblasts, consistent with a reduction in excision repair cross-complementing 1 the nucleotide excision repair enzyme in these cells. The SPARCnull mice showed an increase in both the speed and number of papillomas forming after topical administration of DMBA/TPA to the skin. These papillomas showed reduced growth and reduced progression to a more malignant phenotype, indicating that the effect of SPARC on tumorigenesis depends upon the transformation stage and/or tissue context. These data reinforce a growing number of observations in which SPARC has shown opposite effects on different tumor types/stages.

Extralaryngeal HPV infections in male patients with adult-onset laryngeal papillomatosis

Adult-onset laryngeal papillomatosis is a frequently relapsing disease affecting especially males. We studied the history and prevalence of extralaryngeal HPV infections in these patients to find out their susceptibility to HPV. Of adult-onset laryngeal papilloma male patients treated at Helsinki University Central Hospital over 25 years, we examined 50 for clinical findings, examined Pap and cytological samples from the oral mucosa and urethra and biopsied HPV-suspect lesions. Fifteen female sexual partners underwent gynecological examinations. The history of HPV-associated diseases was also determined from age- and sex-matched control subjects. Of the patients, 16% (8) had a history of genital warts and of the controls, 12.5% (6 of 48). A history of skin warts was more common in patients. Their prevalence of genital warts was higher (3 of 50, 6%) than in the general population (1%, earlier study). Prevalence of oral HPV DNA was 8% (4 of 50). Patients' sexual habits were unexceptional except for an over-representation of high-frequency orogenital sex initiated at a mean of 9.7 years before diagnosis. However, a lack of orogenital contact did not protect them from severe laryngeal disease. Patients with adult-onset laryngeal papillomatosis seem to be prone to HPV infections. Primary laryngeal HPV infection in adolescence may remain latent, requiring cofactors to develop into the clinical disease.