Genetic architecture of mouse skin inflammation and tumour susceptibility

Germline polymorphisms in model organisms and humans influence susceptibility to complex trait diseases such as inflammation and cancer. Mice of the Mus spretus species are resistant to tumour development, and crosses between M. spretus and susceptible Mus musculus strains have been used to map locations of genetic variants that contribute to skin cancer susceptibility. We have integrated germline polymorphisms with gene expression in normal skin from a M. musculus x M. spretus backcross to generate a network view of the gene expression architecture of mouse skin. Here we demonstrate how this approach identifies expression motifs that contribute to tissue organization and biological functions related to inflammation, haematopoiesis, cell cycle control and tumour susceptibility. Motifs associated with inflammation, epidermal barrier function and proliferation are differentially regulated in backcross mice susceptible or resistant to tumour development. The intestinal stem cell marker Lgr5 is identified as a candidate master regulator of the hair follicle, and the vitamin D receptor (Vdr) is linked to coordinated control of epidermal barrier function, inflammation and tumour susceptibility.

miR-124 and miR-137 inhibit proliferation of glioblastoma multiforme cells and induce differentiation of brain tumor stem cells

BACKGROUND

Glioblastoma multiforme (GBM) is an invariably fatal central nervous system tumor despite treatment with surgery, radiation, and chemotherapy. Further insights into the molecular and cellular mechanisms that drive GBM formation are required to improve patient outcome. MicroRNAs are emerging as important regulators of cellular differentiation and proliferation, and have been implicated in the etiology of a variety of cancers, yet the role of microRNAs in GBM remains poorly understood. In this study, we investigated the role of microRNAs in regulating the differentiation and proliferation of neural stem cells and glioblastoma-multiforme tumor cells.

METHODS

We used quantitative RT-PCR to assess microRNA expression in high-grade astrocytomas and adult mouse neural stem cells. To assess the function of candidate microRNAs in high-grade astrocytomas, we transfected miR mimics to cultured-mouse neural stem cells, -mouse oligodendroglioma-derived stem cells, -human glioblastoma multiforme-derived stem cells and -glioblastoma multiforme cell lines. Cellular differentiation was assessed by immunostaining, and cellular proliferation was determined using fluorescence-activated cell sorting.

RESULTS

Our studies revealed that expression levels of microRNA-124 and microRNA-137 were significantly decreased in anaplastic astrocytomas (World Health Organization grade III) and glioblastoma multiforme (World Health Organization grade IV) relative to non-neoplastic brain tissue (P < 0.01), and were increased 8- to 20-fold during differentiation of cultured mouse neural stem cells following growth factor withdrawal. Expression of microRNA-137 was increased 3- to 12-fold in glioblastoma multiforme cell lines U87 and U251 following inhibition of DNA methylation with 5-aza-2'-deoxycytidine (5-aza-dC). Transfection of microRNA-124 or microRNA-137 induced morphological changes and marker expressions consistent with neuronal differentiation in mouse neural stem cells, mouse oligodendroglioma-derived stem cells derived from S100 beta-v-erbB tumors and cluster of differentiation 133+ human glioblastoma multiforme-derived stem cells (SF6969). Transfection of microRNA-124 or microRNA-137 also induced G1 cell cycle arrest in U251 and SF6969 glioblastoma multiforme cells, which was associated with decreased expression of cyclin-dependent kinase 6 and phosphorylated retinoblastoma (pSer 807/811) proteins.

CONCLUSION

microRNA-124 and microRNA-137 induce differentiation of adult mouse neural stem cells, mouse oligodendroglioma-derived stem cells and human glioblastoma multiforme-derived stem cells and induce glioblastoma multiforme cell cycle arrest. These results suggest that targeted delivery of microRNA-124 and/or microRNA-137 to glioblastoma multiforme tumor cells may be therapeutically efficacious for the treatment of this disease.

Amplification of PVT1 contributes to the pathophysiology of ovarian and breast cancer

PURPOSE

This study was designed to elucidate the role of amplification at 8q24 in the pathophysiology of ovarian and breast cancer because increased copy number at this locus is one of the most frequent genomic abnormalities in these cancers.

EXPERIMENTAL DESIGN

To accomplish this, we assessed the association of amplification at 8q24 with outcome in ovarian cancers using fluorescence in situ hybridization to tissue microarrays and measured responses of ovarian and breast cancer cell lines to specific small interfering RNAs against the oncogene MYC and a putative noncoding RNA, PVT1, both of which map to 8q24.

RESULTS

Amplification of 8q24 was associated with significantly reduced survival duration. In addition, small interfering RNA-mediated reduction in either PVT1 or MYC expression inhibited proliferation in breast and ovarian cancer cell lines in which they were both amplified and overexpressed but not in lines in which they were not amplified/overexpressed. Inhibition of PVT1 expression also induced a strong apoptotic response in cell lines in which it was overexpressed but not in lines in which it was not amplified/overexpressed. Inhibition of MYC, on the other hand, did not induce an apoptotic response in cell lines in which MYC was amplified and overexpressed.

CONCLUSIONS

These results suggest that MYC and PVT1 contribute independently to ovarian and breast pathogenesis when overexpressed because of genomic abnormalities. They also suggest that PVT1-mediated inhibition of apoptosis may explain why amplification of 8q24 is associated with reduced survival duration in patients treated with agents that act through apoptotic mechanisms.

Prognostic value of PAI1 in invasive breast cancer: evidence that tumor-specific factors are more important than genetic variation in regulating PAI1 expression

Plasminogen activator inhibitor-1 (PAI1) can promote cancer progression, and its protein expression in tumors is an independent indicator of poor prognosis in many forms of cancer. Here, we show that high PAI1 mRNA levels also predict for shorter overall survival in two independent breast cancer data sets, highlighting the importance of its transcriptional regulation. The -675insG (4G/5G) single-nucleotide polymorphism in the PAI1 gene promoter has been shown to influence PAI1 transcription, with the 4G allele eliciting higher reporter gene expression in vitro and higher levels of circulating PAI1 in vivo. Nevertheless, its genotypic distribution in 2,539 British women with invasive breast cancer was virtually identical to that seen in 1,832 matched controls (P = 0.72), and annual mortality rates for 4G4G, 4G5G, and 5G5G cases were 2.6%, 2.8%, and 3.1% per year, respectively (P = 0.10). Thus, there was no association with breast cancer incidence or outcome, and in a separate set of breast cancers, the 4G/5G single-nucleotide polymorphism showed no association with PAI1 mRNA expression (P = 0.85). By contrast, connective tissue growth factor (CTGF), which can regulate PAI1 expression in culture, was associated with PAI1 expression in three independent cohorts (P << 0.0001). In addition, PAI1 gene copy number differences in the tumors were correlated with PAI1 mRNA expression (P = 0.0005) and seemed to affect expression independently of CTGF. Thus, local factors, such as CTGF and genomic amplification, seem to be more important than germ line genetic variation in influencing PAI1 expression and its untoward effects in breast cancer.

Differential zonal expression and adrenocorticotropin regulation of secreted protein acidic and rich in cysteine (SPARC), a matricellular protein, in the midgestation human fetal adrenal gland: implications for adrenal development

CONTEXT

Matricellular proteins are a group of secreted, multifunctional extracellular matrix glycoproteins that includes thrombospondins (TSPs), tenascin-C, and secreted protein acidic and rich in cysteine (SPARC). They may be implicated in the dynamic developmental processes of the human fetal adrenal (HFA) in which the outer, definitive zone (DZ) cells are postulated to proliferate, migrate centripetally, differentiate, and populate the inner, steroidogenic fetal zone (FZ).

OBJECTIVE

The objective of the study was to identify a matricellular molecule that likely plays a major role in HFA development.

DESIGN

Studies involved RNA, cryosections, and cell cultures from 14- to 23-wk HFAs and human adult adrenal RNA.

MAIN OUTCOME MEASURES

Measures included transcripts encoding matricellular proteins, using real-time quantitative RT-PCR; SPARC localization by immunostaining; and ACTH regulation of SPARC expression and secretion by quantitative RT-PCR and Western blot.

RESULTS

SPARC HFA mRNA was 100-, 700-, and 300-fold higher than TSP-1, TSP-2, and tenascin-C mRNA, respectively. HFA SPARC mRNA was 3-fold higher than adult adrenals (P < 0.005), comparable with levels in adult brain (positive control), whereas mRNAs encoding TSP-1 and TSP-2 were lower in fetal than adult adrenals. SPARC immunoreactivity was detected exclusively in the FZ, not DZ. ACTH, a key regulator of HFA growth and function, increased SPARC mRNA (by 1.7-fold at 1 nm, 48 h, P < 0.05) in isolated FZ cells but not DZ cells. ACTH up-regulation of SPARC protein was also detected in FZ cell lysates and culture medium.

CONCLUSIONS

Results suggest a possible role for SPARC in development of functional and/or structural zonation of the HFA.

Adrenocorticotropin preferentially up-regulates angiopoietin 2 in the human fetal adrenal gland: implications for coordinated adrenal organ growth and angiogenesis

CONTEXT

ACTH is the key tropic hormone for the human fetal adrenal (HFA). Because vascular development must be coordinated with organ growth, ACTH may regulate local angiogenic factors, thereby influencing HFA angiogenesis. We previously demonstrated that ACTH up-regulates vascular endothelial growth factor in HFA cortical cells. A newer angiogenic factor family, the angiopoietins (Angs), also plays critical roles. Ang1 stabilizes, whereas Ang2 destabilizes vessels, increasing responsiveness to angiogenic stimuli.

OBJECTIVE

The objective of this study was to investigate expression and ACTH regulation of Angs and their receptor Tie2 in the HFA.

DESIGN, SETTING, AND PATIENTS

Studies were conducted involving RNA, frozen sections, and primary cell cultures from HFAs (14-24 wk) and human adult adrenal RNA.

MAIN OUTCOME MEASURES

Angs and Tie2 mRNA levels were determined by real-time quantitative RT-PCR, Ang2 and Tie2 were localized by immunostaining, and ACTH regulation of Angs was investigated by real-time quantitative RT-PCR, Western blot, and ELISA.

RESULTS

Mean HFA Ang2 to Ang1 mRNA ratio was 6.3-fold higher than adult adrenals (P < 0.001). Ang2 was localized predominantly in the HFA periphery, whereas Tie2 demonstrated endothelial localization. In isolated HFA cortical cells, ACTH up-regulated Ang mRNA levels in a time- and dose-dependent manner, with the balance favoring Ang2. Ang2 protein levels were elevated in ACTH-stimulated HFA cortical cells and conditioned medium. 8-Bromoadenosine cAMP and forskolin mimicked ACTH effects on the Angs.

CONCLUSIONS

Higher HFA Ang2 to Ang1 ratios may reflect greater vascular remodeling than in the adult. Angs, particularly Ang2, in concert with vascular endothelial growth factor, may mediate ACTH tropic action, ensuring coordination of HFA growth, steroidogenesis, and angiogenesis.

Real-time quantitative polymerase chain reaction: a potential tool for genetic analysis in neuropathology

Since its introduction in the early- to mid-1980s, the polymerase chain reaction (PCR) has been modified and optimized for an increasing number of applications. Early on, the focus was on the amplification of a specific nucleic acid template into quantities amenable to identification and experimental manipulation. While this remains an important application, recent technology has allowed the use of PCR to accurately quantitate the amount of a specific nucleic acid template present in a complex sample. Rather than simply analyzing the final product amount following the course of sequential cycles of amplification, quantitative PCR allows one to measure the accumulation of PCR product during the course of the reaction ("real-time PCR"). Under the appropriate conditions the number of PCR cycles required for the accumulation of a specific amount of product (during the exponential phase of the reaction) is a reflection of the relative amount of nucleic acid template present in the sample under analysis. Real-time quantitative PCR allows one to analyze a relatively large number of samples in a short period of time, potentially allowing multiple markers to be applied on a sample within a time frame consistent with clinical settings. In this overview, we will highlight the uses of real-time quantitative PCR as a potential diagnostic tool in neuropathology, focusing on the analysis of CNS tumors.

Does Familial Non-Medullary Thyroid Cancer Adversely Affect Survival?

BACKGROUND

Familial non-medullary thyroid cancer (FNMTC) is associated with a higher rate of multifocality and a higher recurrence rate than sporadic thyroid cancer. However, the effect of FNMTC on life expectancy is unknown.

MATERIAL AND METHODS

Using data from our FNMTC database, we calculated life expectancy and survival rates after diagnosis of FNMTC and compared the results with the rates for unaffected family members and for the standard US population. Overall life expectancy and survival rates were calculated using the Kaplan-Meier method. We compared patients from families with 2 affected members with patients from families with > or = 3 affected members. We also compared patients diagnosed in a known familial setting (index cases and subsequent cases) with patients diagnosed before the familial setting was recognized.

RESULTS

There were 139 affected patients with 757 unaffected family members. The mean age at diagnosis was 40.8 +/- 13.9 years and the mean follow-up time was 9.4 +/- 11.7 years. Ten patients died of thyroid cancer during follow-up. The life expectancy of patients with FNMTC was similar to that of their unaffected family members. Survival was significantly shorter for patients with 3 or more affected family members, for patients diagnosed before the familial setting was recognized, and for patients with anaplastic cancer.

CONCLUSIONS

Our results suggest that FNMTC may be more aggressive than sporadic thyroid cancer, particularly in families with 3 or more affected members. However, when recognized and treated appropriately, it does not significantly shorten the overall life expectancy of the affected patients.

Copy number aberrations in mouse breast tumors reveal loci and genes important in tumorigenic receptor tyrosine kinase signaling

Receptor tyrosine kinase (RTK) signaling plays a key role in the development of breast cancer. Defining the genes and pathways in the RTK signaling network that are important regulators of tumorigenesis in vivo will unveil potential candidates for targeted therapeutics. To this end, we used microarray comparative genomic hybridization to identify and compare copy number aberrations in five mouse models of breast cancer induced by wild-type and mutated forms of oncogenic ErbB2 or the polyomavirus middle T antigen (PyMT). We observed distinct genomic alterations among the various models, including recurrent chromosome 11 amplifications and chromosome 4 deletions, syntenic with human 17q21-25 and 1p35-36, respectively. Expression of oncogenic Erbb2 (NeuNT) under control of the endogenous Erbb2 promoter results in frequent (85%) amplification at the Erbb2 locus with striking structural similarity to the human amplicon, resulting in overexpression of at least two of the genes, Erbb2 and Grb7. Chromosome 11 amplicons distal to Erbb2 arise in a model (DB) overexpressing a mutant variant of PyMT (Y315/322F) unable to activate phosphatidylinositol 3-kinase. These amplicons are not observed in DB hyperplasias or in tumors overexpressing wild-type PyMT and result in overexpression of Grb2 and Itgb4. Distal chromosome 4 deletions occur in a significantly higher proportion of Erbb2 than PyMT tumors and encompass 14-3-3sigma (Stratifin), which is expressed at low or undetectable levels in the majority of NeuNT tumors. Our studies highlight loci and genes important in the regulation of tumorigenic RTK signaling in mammary epithelial cells in vivo.

In utero angiopoietin-2 gene delivery remodels placental blood vessel phenotype: a murine model for studying placental angiogenesis

Angiopoietin (Ang)-2, the natural antagonist of the Ang1/Tie2 receptor is a complex regulator of blood vessel plasticity that plays a pivotal role in both vessel sprouting [in the presence of vascular endothelial growth factor (VEGF)-A] and vessel regression (in the absence of VEGF-A). Based on the spatial and temporal expression of Ang2 throughout human gestation, we recently suggested that the Ang2 may play a pivotal role in placental angiogenesis. Further, to examine this tenet we have developed a novel murine model system in which in utero Ang2 gene delivery via a non-replicating adenoviral expression vector has the potential to manipulate the blood vessel phenotype in vivo during pregnancy. Ang2 overexpression selectively and rapidly remodels the labyrinth perivascular extracellular matrix, subsequently promoting plasticity of the maternal and fetal vessels, which appear honeycombed due to a 2-fold increase in blood vessel luminal area. High levels of Ang2 impair endothelial cell adhesiveness, leading to vascular leakiness with perivascular oedema, which increases placental weight. These observations suggest that the Ang2 overexpression may play a key role in placental vascular remodelling. Furthermore, we suggest a novel new model to study the pathobiology of placental vascularization and the effect of placental blood vessels on fetal phenotype.

Overexpression of matrix metalloproteinase-1 and -9 mRNA is associated with progression of oral dysplasia to cancer

PURPOSE

Although an important risk factor for oral cancer is the presence of epithelial dysplasia, many lesions will not progress to malignancy. Matrix metalloproteinases (MMPs) are zinc-dependent proteinases capable of digesting various structural components of the extracellular matrix. Because MMPs are frequently overexpressed in oral squamous cell carcinoma (SCC), we hypothesized that they are also overexpressed in oral dysplasias; we also hypothesized that those dysplasias that progress to oral cancer express higher levels of MMPs than those lesions that do not progress.

EXPERIMENTAL DESIGN

In this retrospective study, we examined changes in MMP-1, -2, and -9 mRNA expression using quantitative TaqMan reverse transcription-polymerase chain reaction in 34 routinely processed oral dysplasias and 15 SCCs obtained from 34 patients. After several years of close follow-up, 19 dysplasias progressed to oral SCC and 15 did not.

RESULTS

Overall, MMP-1 mRNA was overexpressed (>2-fold) in 24 of 34 (71%) dysplasias and 13 of 15 (87%) oral SCCs. MMP-2 overexpression was seen in 11 of 34 (32%) dysplasias and 7 of 15 (47%) cancers; for MMP-9, overexpression was identified in 29 of 34 (85%) dysplasias and 15 of 15 (100%) cancers. MMP-1 and -9 levels were significantly higher in the SCCs compared with all oral dysplasias (P = 0.004 and P = 0.01, respectively). MMP-1 and -9 mRNA levels were significantly higher in the oral dysplasias that progressed to oral cancer compared with those that did not (P = 0.04 and P = 0.002, respectively).

CONCLUSIONS

Levels of MMP-1 and -9 mRNA may be markers of malignant transformation of oral dysplasia to oral cancer.

Troglitazone, the peroxisome proliferator-activated receptor-gamma agonist, induces antiproliferation and redifferentiation in human thyroid cancer cell lines

Troglitazone is a potent agonist for the peroxisome proliferator-activated receptor-gamma (PPARgamma) that is a ligand-activated transcription factor regulating cell differentiation and growth. PPARgamma may play a role in thyroid carcinogenesis since PAX8-PPARgamma1 chromosomal translocations are commonly found in follicular thyroid cancers. We investigated the antiproliferative and redifferentiation effects of troglitazone in 6 human thyroid cancer cell lines: TPC-1 (papillary), FTC-133, FTC-236, FTC-238 (follicular), XTC-1 (Hürthle cell), and ARO82-1 (anaplastic) cell lines. PPARgamma was expressed variably in these cell lines. FTC-236 and FTC-238 had a rearranged chromosome at 3p25, possibly implicating the involvement of the PPARgamma encoding gene whereas the other cell lines did not. Troglitazone significantly inhibited cell growth by cell cycle arrest and apoptotic cell death. PPARgamma overexpression did not appear to be a prerequisite for a response to treatment with troglitazone. Troglitazone also downregulated surface expression of CD97, a novel dedifferentiation marker, in FTC-133 cells and upregulated sodium iodide symporter (NIS) mRNA in TPC-1 and FTC-133 cells. Our investigations document that human thyroid cancer cell lines commonly express PPARgamma, but chromosomal translocations involving PPARgamma are uncommon. Troglitazone, a PPARgamma agonist, induced antiproliferation and redifferentiation in thyroid cancer cell lines. PPARgamma agonists may therefore be effective therapeutic agents for the treatment of patients with thyroid cancer that fails to respond to traditional treatments.

The ATM gene is a target for epigenetic silencing in locally advanced breast cancer

Several epidemiological studies on ataxia-telangiectasia families indicate that obligate ATM heterozygotes display an elevated risk for developing breast cancer. However, a molecular basis for a potential link between diminished ATM function and sporadic breast malignancy remains elusive. Here, we show that 78% (18 out of a panel of 23) of surgically removed breast tumors (stage II or greater) displayed aberrant methylation of the ATM proximal promoter region as judged by methylation-specific PCR. Aberrant methylation of the ATM promoter was independently confirmed in several tumors by bisulfite sequencing. Moreover, bisulfite sequencing indicated that this region of the genome is subject to dense methylation. Further, we found a highly significant correlation (P = 0.0006) between reduced ATM mRNA abundance, as measured by real-time RT-PCR, and aberrant methylation of the ATM gene promoter. These findings indicate that epigenetic silencing of ATM expression occurs in locally advanced breast tumors, and establish a link at the molecular level between reduced ATM function and sporadic breast malignancy.

Genome-scale expression profiling of Hutchinson-Gilford progeria syndrome reveals widespread transcriptional misregulation leading to mesodermal/mesenchymal defects and accelerated atherosclerosis

Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disease with widespread phenotypic features resembling premature aging. HGPS was recently shown to be caused by dominant mutations in the LMNA gene, resulting in the in-frame deletion of 50 amino acids near the carboxyl terminus of the encoded lamin A protein. Children with this disease typically succumb to myocardial infarction or stroke caused by severe atherosclerosis at an average age of 13 years. To elucidate further the molecular pathogenesis of this disease, we compared the gene expression patterns of three HGPS fibroblast cell strains heterozygous for the LMNA mutation with three normal, age-matched cell strains. We defined a set of 361 genes (1.1% of the approximately 33,000 genes analysed) that showed at least a 2-fold, statistically significant change. The most prominent categories encode transcription factors and extracellular matrix proteins, many of which are known to function in the tissues severely affected in HGPS. The most affected gene, MEOX2/GAX, is a homeobox transcription factor implicated as a negative regulator of mesodermal tissue proliferation. Thus, at the gene expression level, HGPS shows the hallmarks of a developmental disorder affecting mesodermal and mesenchymal cell lineages. The identification of a large number of genes implicated in atherosclerosis is especially valuable, because it provides clues to pathological processes that can now be investigated in HGPS patients or animal models.

CMRF-35-like molecule-1, a novel mouse myeloid receptor, can inhibit osteoclast formation

By homology to triggering receptor expressed by myeloid cells-2, we screened the mouse expressed sequence tag database and isolated a new single Ig domain receptor, which we have expressed and characterized. The receptor is most similar in sequence to the human CMRF-35 receptor, and thus we have named it CMRF-35-like molecule (CLM)-1. By screening the mouse genome, we determined that CLM-1 was part of a multigene family located on a small segment of mouse chromosome 11. Each contains a single Ig domain, and they are expressed mainly in cells of the myeloid lineage. CLM-1 contains multiple cytoplasmic tyrosine residues, including two that lie in consensus immunoreceptor tyrosine-based inhibitory motifs, and we demonstrate that CLM-1 can associate with Src-homology 2 containing phosphatase-1. Expression of CLM-1 mRNA is down-regulated by treatment with receptor activator of NF-kappaB ligand (RANKL), a cytokine that drives osteoclast formation. Furthermore, expression of CLM-1 in the osteoclastogenic cell line RAW (RAW.CLM-1) prevents osteoclastogenesis induced by RANKL and TGF-beta. RAW.CLM-1 cells fail to multinucleate and do not up-regulate calcitonin receptor, but they express tartrate-resistant acid phosphatase, cathepsin K, and beta(3) integrin, suggesting that osteoclastogenesis is blocked at a late-intermediate stage. Thus, we define a new family of myeloid receptors, and demonstrate that the first member of this family, CLM-1, is an inhibitory receptor, able to block osteoclastogenesis.

Quantitative analysis of cathepsin L mRNA and protein expression during oral cancer progression

Although an important risk factor for oral cancer is the presence of epithelial dysplasia, most of these lesions will not progress to malignancy. Presently, for the individual patient with dysplasia, there are few reliable markers that may indicate the likelihood of progression to oral cancer. Cathepsin L is a lysosomal protease that degrades extracellular matrix material. Because cathepsin L is frequently overexpressed in oral squamous cell carcinoma (SCC) we hypothesized that it is also overexpressed in oral premalignancy and that premalignant lesions that progressed to oral cancer expressed higher levels of cathepsin L than those premalignant lesions that did not. In this retrospective pilot study we examined changes in cathepsin L expression at the mRNA level using quantitative TaqMan RT-PCR and at the protein level by immunohistochemistry in 33 routinely processed oral dysplastic lesions and 14 SCCs obtained from 33 patients. Sixteen of the dysplastic lesions progressed to oral SCC and 17 did not after several years of follow-up. Cathepsin L mRNA was overexpressed in 16/33 (48%) dysplastic lesions and in 9/14 (64%) oral SCC. Cathepsin L protein was also overexpressed in a large proportion of dysplasias and cancers. Overexpression was independent of dysplasia grade and identified in both those patients who progressed to oral SCC and in those who did not. Levels of cathepsin L mRNA and protein did not differ significantly in the progressing versus non-progressing dysplasias (P=0.27). However, cathepsin L mRNA and protein were significantly lower in the non-progressing dysplasias when compared to the oral cancers (P=0.03) but not in the progressing dysplasias suggesting a trend for dysplasias with overexpressed cathepsin L to be more likely to progress to oral cancer.

Expression of vascular endothelial growth factor-C in benign and malignant thyroid tumors

In contrast to vascular endothelial growth factor (VEGF), which stimulates angiogenesis, VEGF-C is thought to stimulate lymphangiogenesis. The role of VEGF-C in thyroid cancer pathogenesis has not been clarified. One might expect a different pattern of VEGF-C expression in the various types of thyroid cancer because of their different means of metastases. In this investigation, we determined whether the differential expression of VEGF-C might explain the different propensity to lymph node metastasis in thyroid cancers. One hundred eleven normal and neoplastic thyroid tissues were analyzed by real-time quantitative PCR. Papillary thyroid cancers had a higher VEGF-C expression than other thyroid malignancies (P < 0.0005 ANOVA). Among the normal thyroid tissues from patients with malignant or benign thyroid diseases, there was no significant difference in VEGF-C expression. Paired comparison of VEGF-C expression between thyroid cancers and normal thyroid tissues from the same patients showed a significant increase of VEGF-C expression in papillary thyroid cancer (1.10 +/- 0.41 vs. 0.70 +/- 0.13; P = 0.001) and a significant decrease of VEGF-C expression in medullary thyroid cancer (0.11 +/- 0.13 vs. 0.78 +/- 0.29; P = 0.001). In contrast, there was no significant difference of VEGF-C expression between cancer and normal tissues in other types of thyroid cancer. In summary, VEGF-C expression is increased in papillary thyroid cancer, compared with paired normal thyroid tissues, but not in other thyroid cancers that are also prone to lymph node metastasis. The lymphangiogenic role of VEGF-C in thyroid cancers therefore appears to be complex and other factors are likely to be also involved.

Diagnostic and prognostic value of fas and telomeric-repeat binding factor-1 genes in adrenal tumors

It is often difficult to distinguish histologically between an adrenal cortical cancer and a benign adenoma, or to predict the prognosis of patients with adrenal cortical cancers. In this investigation, we examined whether apoptosis-regulating genes, bcl-xL and fas, and a telomere-related gene, telomeric-repeat binding factor-1 (TRF-1), differ between adrenal cortical cancers and benign adrenal tumors. Tissues from 4 adrenal cortical cancers were compared with 7 normal adrenal tissues, 17 cortical adenomas, 4 cortical hyperplasias, and 20 pheochromocytomas for expressions of bcl-xL and fas by RT-PCR, and for expressions of TRF-1 by real-time quantitative RT-PCR. All benign adrenal tissues expressed both the antiapoptosis gene, bcl-xL, and proapoptosis gene, fas, but the adrenal cortical cancers expressed only bcl-xL and not fas. TRF-1 increased by more than 30-fold in the adrenal cortical cancers, compared with benign adrenal tissues, and inversely correlated with the prognosis of patients with the adrenal cortical cancers. This lack of expression of fas in adrenal cortical cancer may help to distinguish it from benign adrenal tumors. The level of TRF-1 expression may be helpful prognostically for patients with adrenal cortical cancers.

Human placental vascular development: vasculogenic and angiogenic (branching and nonbranching) transformation is regulated by vascular endothelial growth factor-A, angiopoietin-1, and angiopoietin-2

During placental development, vessel formation occurs initially by vasculogenesis and subsequently by branching and nonbranching angiogenesis. We investigated vascular endothelial growth factor (VEGF)-A, angiopoietin (Ang)-1 and -2 transcript profiles, and the protein products that they encode in placentas from normotensive pregnancies throughout pregnancy. In addition, we compared these genes in placentas from normotensive women and those with preeclampsia during the third trimester. Quantitative real-time PCR analysis demonstrated that VEGF-A and Ang1 mRNA increased in a linear pattern by 2.5 (not significant) and 2.8%/wk (P = 0.034), respectively, whereas Ang2 decreased logarithmically by 3.5%/wk (P = 0.0003). Ang2 mRNA was 400- and 100-fold higher than Ang1 and VEGF-A, respectively, in the first trimester and declined to 20-fold and 7-fold in the third. Ang2 protein (ELISA) decreased by 4.7%/wk (P = 0.0001), whereas Ang1 and VEGF-A were undetectable. In preeclampsia compared with normotensive pregnancy, only VEGF-A mRNA increased significantly, by 3-fold (P = 0.006). This increase may be related to low oxygen tension, as VEGF-A is up-regulated by hypoxia. In situ hybridization and immunohistochemical studies revealed that VEGF-A was localized in cyto- and syncytiotrophoblast and perivascular cells, whereas Ang1 and Ang2 were only in syncytiotrophoblast and perivascular cells in the immature intermediate villi during the first and second trimesters, and mature intermediate and terminal villi during the third trimester. These data suggest that these molecules may play important roles in placental biology and chorionic villus vascular development and remodeling in an autocrine/paracrine manner. The tight correlation between Ang2 mRNA and protein indicates that regulation of placental vascular development occurs at the transcriptional, and not translational, level.

Effect of duration of fixation on quantitative reverse transcription polymerase chain reaction analyses

Increasingly, there is the need to analyze gene expression in tumor tissues and correlate these findings with clinical outcome. Because there are few tissue banks containing enough frozen material suitable for large-scale genetic analyses, methods to isolate and quantify messenger RNA (mRNA) from formalin-fixed, paraffin-embedded tissue sections are needed. Recovery of RNA from routinely processed biopsies and quantification by the polymerase chain reaction (PCR) has been reported; however, the effects of formalin fixation have not been well studied. We used a proteinase K-salt precipitation RNA isolation protocol followed by TaqMan quantitative PCR to compare the effect of formalin fixation for 24, 48, and 72 hours and for 1 week in normal (2), oral epithelial dysplasia (3), and oral squamous cell carcinoma (4) specimens yielding 9 fresh and 36 formalin-fixed samples. We also compared mRNA and protein expression levels using immunohistochemistry for epidermal growth factor receptor (EGFR), matrix metalloproteinase (MMP)-1, p21, and vascular endothelial growth factor (VEGF) in 15 randomly selected and routinely processed oral carcinomas. We were able to extract RNA suitable for quantitative reverse transcription (RT) from all fresh (9/9) and formalin-fixed (36/36) specimens fixed for differing lengths of time and from all (15/15) randomly selected oral squamous cell carcinoma. We found that prolonged formalin fixation (>48 h) had a detrimental effect on quantitative RT polymerase chain reaction results that was most marked for MMP-1 and VEGF but less evident for p21 and EGFR. Comparisons of quantitative RT polymerase chain reaction and immunohistochemistry showed that for all markers, except p21, there was good correlation between mRNA and protein levels. p21 mRNA was overexpressed in only one case, but protein levels were elevated in all but one tumor, consistent with the established translational regulation of p21. These results show that RNA can be reliably isolated from formalin-fixed, paraffin-embedded tissue sections and can produce reliable quantitative RT-PCR data. However, results for some markers are adversely affected by prolonged formalin fixation times.

Gene quantification using real-time quantitative PCR: an emerging technology hits the mainstream

The recent flood of reports using real-time Q-PCR testifies to the transformation of this technology from an experimental tool into the scientific mainstream. Many of the applications of real-time Q-PCR include measuring mRNA expression levels, DNA copy number, transgene copy number and expression analysis, allelic discrimination, and measuring viral titers. The range of applications of real-time Q-PCR is immense and has been fueled in part by the proliferation of lower-cost instrumentation and reagents. Successful application of real-time Q-PCR is not trivial. However, this review will help guide the reader through the variables that can limit the usefulness of this technology. Careful consideration of the assay design, template preparation, and analytical methods are essential for accurate gene quantification.

Induction of hypervascularity without leakage or inflammation in transgenic mice overexpressing hypoxia-inducible factor-1alpha

Hypoxia-inducible factor-1alpha (HIF-1alpha) transactivates genes required for energy metabolism and tissue perfusion and is necessary for embryonic development and tumor explant growth. HIF-1alpha is overexpressed during carcinogenesis, myocardial infarction, and wound healing; however, the biological consequences of HIF-1alpha overexpression are unknown. Here, transgenic mice expressing constitutively active HIF-1alpha in epidermis displayed a 66% increase in dermal capillaries, a 13-fold elevation of total vascular endothelial growth factor (VEGF) expression, and a six- to ninefold induction of each VEGF isoform. Despite marked induction of hypervascularity, HIF-1alpha did not induce edema, inflammation, or vascular leakage, phenotypes developing in transgenic mice overexpressing VEGF cDNA in skin. Remarkably, blood vessel leakage resistance induced by HIF-1alpha overexpression was not caused by up-regulation of angiopoietin-1 or angiopoietin-2. Hypervascularity induced by HIF-1alpha could improve therapy of tissue ischemia.

Detection of 1p and 19q loss in oligodendroglioma by quantitative microsatellite analysis, a real-time quantitative polymerase chain reaction assay

The combined loss of chromosomes 1p and 19q has recently emerged as a genetic predictor of chemosensitivity in anaplastic oligodendrogliomas. Here, we describe a strategy that uses a novel method of real-time quantitative polymerase chain reaction, quantitative microsatellite analysis (QuMA), for the molecular analysis of 1p and 19q loss in oligodendrogliomas and oligoastrocytomas in archival routinely processed paraffin material. QuMA is performed on the ABI 7700 and based on amplifications of microsatellite loci that contain (CA)n repeats where the repeat itself is the target for hybridization by the fluorescently labeled probe. This single probe can therefore be used to determine copy number of microsatellite loci spread throughout the human genome. In genomic DNA prepared from paraffin-embedded brain tumor specimens, QuMA detected combined loss of 1p and 19q in 64% (21 of 32) of oligodendrogliomas and 67% (6 of 9) of oligoastrocytomas. We validate the use of QuMA as a reliable method to detect copy number by showing concordance between QuMA and fluorescence in situ hybridization at 37 of 45 chromosomal arms tested. These results indicate that QuMA is an accurate, high-throughput assay for the detection of copy number at multiple loci; as many as 31 loci of an individual tumor can be analyzed on a 96-well plate in a single 2-hour run. In addition, it has advantages over standard allelic imbalance/loss of heterozygosity assays in that all loci are potentially informative, paired normal tissue is not required, and gain can be distinguished from loss. QuMA may therefore be a powerful molecular tool to expedite the genotypic analysis of human gliomas in a clinical setting for diagnostic/prognostic purposes.

Maternal expression of functional lipoprotein lipase and effects on body fat mass and body condition scores of mature cats with lipoprotein lipase deficiency

OBJECTIVE

To assess effects of deficiency of lipoprotein lipase (LPL) on body condition scores and lean and fat body masses of adult cats.

ANIMALS

12 cats without LPL mutations and 23 cats that were heterozygous or homozygous carriers of the Gly412Arg LPL mutation.

PROCEDURE

Lean and fat body masses were estimated by use of body condition scores and change in enrichment of serum after IV administration of deuterium oxide. Mass spectroscopy and infrared absorbance methods were used to determine deuterium enrichment.

RESULTS

Fat body mass (mean +/- SD; 0.2 +/- 0.1 kg) and percentage body fat (6.2 +/- 1.4%) of homozygotes were significantly less than those of clinically normal cats and heterozygotes (0.7 +/- 0.1 kg, 18.2 +/- 1.6% and 0.5 +/- 0.1 kg, 15.6 +/- 1.7%, respectively). Homozygous offspring of homozygous dams had significantly less fat body mass (0.1 +/- 0.1 kg) and percentage body fat (2.1 +/- 1.0%) than homozygous offspring of heterozygous dams (0.3 +/- 0.1 kg and 9.2 +/- 1.7%, respectively). Lean body mass did not differ significantly among groups. For all groups, percentage body fat was significantly correlated with body condition score (r= 0.65), and body condition scores supported findings for fat body mass.

CONCLUSIONS AND CLINICAL RELEVANCE

Deficiency of LPL activity in cats diminishes stores of body fat. This is consistent with a low rate of de novo synthesis of fat. The effect of dam on body masses in mature LPL-deficient cats indicates nutrient programming of adipose formation during gestation or lactation.

Measurement of DNA copy number at microsatellite loci using quantitative PCR analysis

This report describes the development and validation of quantitative microsatellite analysis (QuMA) for rapid measurement of relative DNA sequence copy number. In QuMA, the copy number of a test locus relative to a pooled reference is assessed using quantitative, real-time PCR amplification of loci carrying simple sequence repeats. Use of simple sequence repeats is advantageous because of the large numbers that are mapped precisely. In addition, all markers are informative because QuMA does not require that they be polymorphic. The utility of QuMA is demonstrated in assessment of the extent of deletions of chromosome 2 in leukemias arising in radiation-sensitive inbred SJL mice and in analysis of the association of increased copy number of the putative oncogene ZNF217 with reduced survival duration in ovarian cancer patients.

An approach to analysis of large-scale correlations between genome changes and clinical endpoints in ovarian cancer

This report describes analyses of associations of genome copy number abnormalities in ovarian cancers with clinical features using genome-wide graphical and analytical procedures. These studies show that tumor grade is a better indicator of the extent of genomic progression than stage, that loss of chromosome 4 occurs preferentially in high-grade tumors, and that gains of 3q26-qter, 8q24-qter, and 20q13-qter occur frequently in low-grade and low-stage tumors and thus may be early events in ovarian cancer development. In addition, loss of chromosome 16q24 and a total number of independent genome copy number aberrations >7 are associated with reduced survival duration. The association of loss of 16q24 (D16S3026) with decreased survival duration was confirmed by quantitative PCR. Regions that frequently are abnormal and associated with altered survival duration are strong candidates for higher resolution analysis and gene discovery and may be useful markers for prediction of clinical outcome.

Lipid and lipoprotein analysis of cats with lipoprotein lipase deficiency

BACKGROUND

We have previously described a colony of domestic cats with a naturally occurring mutation in the lipoprotein lipase (LPL) gene. We have now further characterized cats homozygous for LPL deficiency (LPL -/-, homozygotes), and have contrasted these with heterozygotes (LPL +/-) and normal cats (LPL +/+).

MATERIALS AND METHODS

Density gradient ultracentrifugation with subsequent lipid analysis, agarose and polyacrylamide gel electrophoresis was used to examine detailed liproprotein differences between the genotypes. Oral fat loading studies and breast milk fatty acid analysis were also performed to further characterize the phenotypic expression of LPL deficiency in this model system.

RESULTS

Several lipid abnormalities associated with homozygosity for LPL deficiency were evident. Triglyceride-rich lipoprotein-triglycerides (TRL-TG) and cholesterol (TRL-C) were higher (TRL-TG 2.09 +/- 1.14 vs. 0.15 +/- 0.04 mmol L-1, P < 0.001; TRL-C 0.42 +/- 0.30 vs. 0.11 +/- 0.16 mmol L-1, P < 0.05) in male -/- than in male +/+ cats, as was HDL-cholesterol (HDL-C, 1.75 +/- 0.24 vs. 1.41 +/- 0.14 mmol L-1, P < 0.05). LDL-C levels were lower in homozygous cats than in control cats, similar to what is seen in human LPL deficiency. Oral fat loading studies revealed that homozygous cats have a marked reduced ability to clear plasma TGs in terms of peak time (7 h vs. 3 h), peak height (9.36 vs. 1.1 mmol L-1), area under the TG clearance curve (AUC, 280.3 vs. 2.2 h mmol L-1) and time to return to baseline. Fasting lipid and lipoprotein levels were not significantly different between heterozygous and normal cats. However, oral fat loading in heterozygotes revealed an intermediate phenotype (peak of 2.35 mmol L-1 at 5 h, AUC 13.1 h mmol L-1), highlighting the impaired TG clearance in these animals.

CONCLUSION

Thus, LPL deficiency in the cat results in a lipid and lipoprotein phenotype that predominantly parallels human LPL deficiency, further validating the use of these animals in studies on the pathobiology of LPL.

Diet-induced atherosclerosis in the domestic cat

The domestic cat has not been used in studies of atherosclerosis, with the exception of a single study published in 1970. We have further evaluated the susceptibility of the domestic cat to diet-induced atherosclerosis, the ultimate intent being to discern the atherogenic risk due to lipoprotein lipase deficiency in an affected feline kindred with a phenotype very similar to that of the human form of this condition. We subjected a group of normal domestic cats to a moderately high-fat, cholesterol-enriched diet (30% fat and 3% cholesterol) for a period of 2 to 8 months. Plasma lipid levels were monitored monthly. At the time of killing, all organs and the entire vascular tree were removed, sectioned, processed, and stained with hematoxylin and eosin. The entire vascular tree was also stained with Movat's pentachrome and oil red O (ORO) and assessed semiquantitatively (0 to 5+/5+) and quantitatively (mean intimal area and ORO positivity, mm2). Both blood lipid measurements (total cholesterol, high-density lipoprotein-cholesterol, triglycerides, and low-density lipoprotein-cholesterol) and vessel wall lesion assessment (intimal area, mm2) were statistically elevated (p < 0.05) in the cholesterol-fed cats as compared to those on a normal diet. The highest correlations obtained between blood lipid components and vessel wall measures were the percent increase in triglyceride from base line versus the ORO measurement or foam cell grade (r = 0.86), and percent increase in triglycerides versus the intimal area in the lower abdominal aorta (r = 0.91). Similar relationships were found when the intimal area in the brachiocephalic/subclavian vessels was correlated with the absolute triglyceride values (r = 0.85) or with the percent increase in triglycerides (r = 0.83). Thus, we produced atherosclerotic lesions in the cat within 2 to 4 months on a cholesterol-enriched diet; blood lipid levels were highly correlated with lesional measurements in the vessel wall. This study will provide the basis for evaluation of the susceptibility of New Zealand lipoprotein lipase-deficient cats to diet-induced atherosclerosis.

Efficient adenovirus-mediated ectopic gene expression of human lipoprotein lipase in human hepatic (HepG2) cells

Gene therapy to deliver and express a corrective lipoprotein lipase (LPL) gene may improve the lipid profile and reduce the morbidity and potential atherogenic risk from hypertriglyceridemia and dyslipoproteinemia in patients with complete or partial LPL deficiency. We have used an E1-/E3- adenoviral vector, with an RSV-driven human LPL cDNA expression cassette (Ad-RSV-LPL), to achieve high ectopic LPL gene expression in the human hepatoma cell line HepG2, an accepted hepatocellular model of lipoprotein metabolism. Ad-RSV-LPL transduction of HepG2 cells with a multiplicity of infection (moi) between 12.5 and 100 yielded dose-dependent increments in LPL mass and activity. Peak levels of LPL protein of 2,032.1 +/- 274.5 ng/10(5) cells per ml (mol 100) correlated with increased activity of 92.7 +/- 22.6 mU/10(5) cells per ml relative to negligible LPL levels in Ad-RSV-LacZ (beta-galactosidase) controls. Exogenous LPL expression over a 5-day period peaked at day 3. Susceptibility to inhibition by 1 M NaCl and an anti-LPL monoclonal antibody confirmed that lipase activity was indeed derived from human LPL. Hydrolysis, by LPL-overexpressing HepG2 cells, of TG carried in very-low-density lipoprotein (VLDL) showed that greater than 50% of the triglycerides (TG) disappeared after 4 hr of incubation. These results were compatible with FPLC evidence of a marked reduction in VLDL-TG. These results provide strong in vitro evidence that adenoviral-mediated ectopic expression of the human LPL gene could render hepatic cells capable of VLDL catabolism and thus support the possibility for in vivo adenoviral vector-mediated liver-targeted LPL gene therapy.

Silk properties determined by gland-specific expression of a spider fibroin gene family

Spiders produce a variety of silks that range from Lycra-like elastic fibers to Kevlar-like superfibers. A gene family from the spider Araneus diadematus was found to encode silk-forming proteins (fibroins) with different proportions of amorphous glycine-rich domains and crystal domains built from poly(alanine) and poly(glycine-alanine) repeat motifs. Spiders produce silks of different composition by gland-specific expression of this gene family, which allows for a range of mechanical properties according to the crystal-forming potential of the constituent fibroins. These principles of fiber property control may be important in the development of genetically engineered structural proteins.

A mutation in the lipoprotein lipase gene is the molecular basis of chylomicronemia in a colony of domestic cats

Members of a domestic cat colony with chylomicronemia share many phenotypic features with human lipoprotein lipase (LPL) deficiency. Biochemical analysis reveals that these cats do have defective LPL catalytic activity and have a clinical phenotype very similar to human LPL deficiency. To determine the molecular basis underlying this biochemical phenotype, we have cloned the normal and affected cat LPL cDNAs and shown that the affected cat has a nucleotide change resulting in a substitution of arginine for glycine at residue 412 in exon 8. In vitro mutagenesis and expression studies, in addition to segregation analysis, have shown that this DNA change is the cause of LPL deficiency in this cat colony. Reduced body mass, growth rates, and increased stillbirth rates are observed in cats homozygous for this mutation. These findings show that this LPL deficient cat can serve as an animal model of human LPL deficiency and will be useful for in vivo investigation of the relationship between triglyceride rich lipoproteins and atherogenic risk and for the assessment of new approaches for treatment of LPL deficiency, including gene therapy.

Cloning and mapping of the alpha-adducin gene close to D4S95 and assessment of its relationship to Huntington disease

The genetic defect underlying Huntington's disease (HD) has been mapped to 4p16.3. Refined localization using recombinant HD chromosome analysis and allelic association analyses have identified two distinct candidate regions. Using a cDNA hybrid selection procedure we have cloned the gene for alpha-adducin, a subunit of a cytoskeletal protein crucial for spectrin-actin membrane plasticity. This gene maps to the proximal 2.2 Mb candidate region within 20 kb of D4S95. Alleles of markers at this locus have been shown to exhibit significant linkage disequilibrium with HD. A 4 kb alpha-adducin transcript was identified which is abundantly expressed in the caudate nucleus, the site of major neuronal loss in HD. Sequencing of the brain alpha-adducin cDNA from two HD patients and an age-matched control did not detect any sequence alterations specific to HD. However, we identified in brain cDNA of both patients and control samples, two alternately spliced brain exons, not previously described in the erythrocyte cDNA. A 93 bp exon is inserted in frame between codon 471 and 472 while a 34 bp exon inserted within codon 621 disrupts the frame and introduces a stop codon after 11 novel amino acids. The mapping of the adducin gene adjacent to D4S95 and its pattern of expression, as well as its potential for distinct alternately spliced variants, reinforces the necessity to accurately assess the role of the expression of this gene in the pathogenesis of HD.

The human loci DNF15S2 and D3S94 have a high degree of sequence similarity to acyl-peptide hydrolase and are located at 3p21.3

The short arm of chromosome 3 undergoes genetic loss in most small-cell lung cancers and renal cell carcinomas. The most frequently deleted region includes the DNF15S2 locus (mapped to 3p21), suggesting that a putative recessive tumor-suppressor gene might be located nearby. A cosmid clone, cA476, contains the D3S94 locus and two HTF islands and detects a PstI RFLP. We have isolated cDNAs homologous to conserved fragments within cA476; and these cDNAs have 96% sequence similarity to a cDNA derived from the DNF15S2 locus. Sequence information from cDNAs derived from both the rat and pig acyl-peptide hydrolase (E.C.3.4.19.1) gene show that they have a high degree of sequence similarity to cDNAs derived from D3S94 and DNF15S2, suggesting that they are all the same locus. Cosmid cA476 (DNF15S2) has been mapped, by fluorescent in situ hybridization, to chromosome 3p21.3. D3S94 and DNF15S2 are quite distinct from aminoacylase 1 (ACY1), which has been physically linked to D3S2, D3S92, and D3S93, all localized within 3p21.1.