Panx3 links body mass index and tumorigenesis in a genetically heterogeneous mouse model of carcinogen-induced cancer.

BACKGROUND: Body mass index (BMI) has been implicated as a primary factor influencing cancer development. However, understanding the relationship between these two complex traits has been confounded by both environmental and genetic heterogeneity. METHODS: In order to gain insight into the genetic factors linking BMI and cancer, we performed chemical carcinogenesis on a genetically heterogeneous cohort of interspecific backcross mice ((Mus Spretus × FVB/N) F1 × FVB/N). Using this cohort, we performed quantitative trait loci (QTL) analysis to identify regions linked to BMI. We then performed an integrated analysis incorporating gene expression, sequence comparison between strains, and gene expression network analysis to identify candidate genes influencing both tumor development and BMI. RESULTS: Analysis of QTL linked to tumorigenesis and BMI identified several loci associated with both phenotypes. Exploring these loci in greater detail revealed a novel relationship between the Pannexin 3 gene (Panx3) and both BMI and tumorigenesis. Panx3 is positively associated with BMI and is strongly tied to a lipid metabolism gene expression network. Pre-treatment Panx3 gene expression levels in normal skin are associated with tumor susceptibility and inhibition of Panx function strongly influences inflammation. CONCLUSIONS: These studies have identified several genetic loci that influence both BMI and carcinogenesis and implicate Panx3 as a candidate gene that links these phenotypes through its effects on inflammation and lipid metabolism.

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.

The prevalence of folate-remedial MTHFR enzyme variants in humans.

Studies of rare, inborn metabolic diseases establish that the phenotypes of some mutations in vitamin-dependent enzymes can be suppressed by supplementation of the cognate vitamin, which restores function of the defective enzyme. To determine whether polymorphisms exist that more subtly affect enzymes yet are augmentable in the same way, we sequenced the coding region of a prototypical vitamin-dependent enzyme, methylenetetrahydrofolate reductase (MTHFR), from 564 individuals of diverse ethnicities. All nonsynonymous changes were evaluated in functional in vivo assays in Saccharomyces cerevisiae to identify enzymatic defects and folate remediability of impaired alleles. We identified 14 nonsynonymous changes: 11 alleles with minor allele frequencies <1% and 3 common alleles (A222V, E429A, and R594Q). Four of 11 low-frequency alleles affected enzyme function, as did A222V. Of the five impaired alleles, four could be restored to normal functionality by elevating intracellular folate levels. All five impaired alleles mapped to the N-terminal catalytic domain of the enzyme, whereas changes in the C-terminal regulatory domain had little effect on activity. Impaired activity correlated with the phosphorylation state of MTHFR, with more severe mutations resulting in lower abundance of the phosphorylated protein. Significantly, diploid yeast heterozygous for mutant alleles were impaired for growth, particularly with lower folate supplementation. These results suggested that multiple less-frequent alleles, in aggregate, might significantly contribute to metabolic dysfunction. Furthermore, vitamin remediation of mutant enzymes may be a common phenomenon in certain domains of proteins.

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.

655Val and 1170Pro ERBB2 SNPs in familial breast cancer risk and BRCA1 alterations.

Human ERBB2 presents several SNPs. One of these, Ile655Val, introduces a structural change in the transmembrane region of ERBB2 and has been the focus of debate over its potential role as a susceptibility marker for breast cancer risk. Another SNP, Ala1170Pro, introduces a structural change in the carboxyl-terminal regulatory domain of the protein, but its clinical and biological importance remains undefined. The aim of this study was to investigate the association of rare alleles of both SNPs and the risk of developing breast cancer, BRCA1 alterations and clinical-pathological features of Caucasian breast cancer patients with familial history of breast/ovarian cancer. The originality of the present paper is that it is the only specifically focusing on the relationship between ERBB2 SNPs and familiarity/BRCA1 characteristics. A consecutive series of 628 patients with first diagnosis of breast cancer and 169 healthy people had DNA analyzed for both SNPs. Genotypic or allelic frequencies of ERBB2 SNPs in breast cancer patients were similar than in controls. The variant allele 655Val was significantly associated with younger age (p=0.009) particularly associated with patient family history of breast cancer (p=0.02). The 655Val allele was also more commonly found in invasive, while the variant 1170Pro in estrogen receptor positive breast cancers. Furthermore, this last SNP seems to be strictly associated with the presence of BRCA1 polymorphisms. In conclusion, these findings point to the existence of an association of ERBB2 allelic variants at both loci with specific breast tumor phenotypes and to the need of deeply investigate different gene SNPs association for risk defining.

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.

Altered promoter usage characterizes monoallelic transcription arising with ERBB2 amplification in human breast cancers.

Analysis of a collection of human breast cancers (n = 150), enriched in ERBB2-positive cases (n = 57) and involving tumor genotyping relative to population-matched blood genotyping (n = 749) for a common ERBB2 single nucleotide polymorphism Ala(G)1170Pro(C), revealed that ERBB2 amplification in breast cancer is invariably monoallelic. Analysis of paired breast cancer and blood samples from informative (G1170C heterozygotic) ERBB2-positive (n = 12) and ERBB2-negative (n = 17) cases not only confirmed monoallelic amplification and ERBB2 transcriptional overexpression but also revealed that most low ERBB2 expressing breast cancers (12/17) exhibit unbalanced allelic transcription, showing 3-fold to nearly 5,000-fold preferential expression from one of two inherited alleles. To explore cis-acting transcriptional mechanisms potentially selected during ERBB2 amplification, levels of four different ERBB2 transcript variants (5.2, 4.7, 2.1, and 1.4 kb) were correlated with total (4.6 kb) ERBB2 mRNA levels in ERBB2-positive (n = 14) versus ERBB2-negative (n = 43) primary breast cancers. Relative expression of only the 2.1 kb extracellular domain-encoding splice variant and a 4.7 kb mRNA variant that uses an alternative start site were significantly increased in association with ERBB2-positivity, implicating altered promoter usage and selective transcript regulation within the ERBB2 amplicon. Altogether, these findings provide new mechanistic insights into the development of ERBB2-positive breast cancer and strong rationale for delineating candidate cis-acting regulatory elements that may link allele-specific ERBB2 transcription in premalignant breast epithelia with subsequent development of breast cancers bearing monoallelic ERBB2 amplicons.

Optimized high-throughput microRNA expression profiling provides novel biomarker assessment of clinical prostate and breast cancer biopsies.

BACKGROUND: Recent studies indicate that microRNAs (miRNAs) are mechanistically involved in the development of various human malignancies, suggesting that they represent a promising new class of cancer biomarkers. However, previously reported methods for measuring miRNA expression consume large amounts of tissue, prohibiting high-throughput miRNA profiling from typically small clinical samples such as excision or core needle biopsies of breast or prostate cancer. Here we describe a novel combination of linear amplification and labeling of miRNA for highly sensitive expression microarray profiling requiring only picogram quantities of purified microRNA. RESULTS: Comparison of microarray and qRT-PCR measured miRNA levels from two different prostate cancer cell lines showed concordance between the two platforms (Pearson correlation R2 = 0.81); and extension of the amplification, labeling and microarray platform was successfully demonstrated using clinical core and excision biopsy samples from breast and prostate cancer patients. Unsupervised clustering analysis of the prostate biopsy microarrays separated advanced and metastatic prostate cancers from pooled normal prostatic samples and from a non-malignant precursor lesion. Unsupervised clustering of the breast cancer microarrays significantly distinguished ErbB2-positive/ER-negative, ErbB2-positive/ER-positive, and ErbB2-negative/ER-positive breast cancer phenotypes (Fisher exact test, p = 0.03); as well, supervised analysis of these microarray profiles identified distinct miRNA subsets distinguishing ErbB2-positive from ErbB2-negative and ER-positive from ER-negative breast cancers, independent of other clinically important parameters (patient age; tumor size, node status and proliferation index). CONCLUSION: In sum, these findings demonstrate that optimized high-throughput microRNA expression profiling offers novel biomarker identification from typically small clinical samples such as breast and prostate cancer biopsies.

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.

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.

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.

Gene expression and angiotropism in primary CNS lymphoma.

Primary CNS lymphoma is an aggressive form of non-Hodgkin lymphoma whose growth is restricted to the central nervous system. We used cDNA microarray analysis to compare the gene expression signature of primary CNS lymphomas with nodal large B-cell lymphomas. Here, we show that while individual cases of primary CNS lymphomas may be classified as germinal center B-cell, activated B-cell, or type 3 large B-cell lymphoma, brain lymphomas are distinguished from nodal large B-cell lymphomas by high expression of regulators of the unfolded protein response (UPR) signaling pathway, by the oncogenes c-Myc and Pim-1, and by distinct regulators of apoptosis. We demonstrate that interleukin-4 (IL-4) is expressed by tumor vasculature as well as by tumor cells in CNS lymphomas. We also identify high expression in CNS lymphomas of several IL-4-induced genes, including X-box binding protein 1 (XBP-1), a regulator of the UPR. In addition, we demonstrate expression of the activated form of STAT6, a mediator of IL-4 signaling, by tumor cells and tumor endothelia in CNS lymphomas. High expression of activated STAT6 in tumors was associated with short survival in an independent set of patients with primary CNS lymphoma who were treated with high-dose intravenous methotrexate therapy.

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.

High-resolution analysis of genomic alterations and human papillomavirus integration in anal intraepithelial neoplasia.

Anal intraepithelial neoplasia (AIN) is the likely precursor to anal cancer. AIN is associated with human papillomavirus (HPV) infection, and HPV-associated genomic instability may play an important role in the progression of squamous intraepithelial neoplasia to cancer. Microarray-based comparative genome hybridization (aCGH) was performed on DNA from AIN specimens to determine the host genomic alterations and their correlation with HPV DNA integration or rearrangement. Of 27 high-grade AIN specimens tested by CGH, 8 (30%) showed regional DNA copy number abnormalities (CNAs). Five additional cases previously identified by chromosome CGH to carry CNAs were reanalyzed by aCGH and pooled with the 8 new cases for analysis. The most common regions of gain were on chromosome arms 1p, 1q, 3q, 8p, and 20q. The most common regions of loss were on chromosome arms 2q, 7q, 11p, 11q, and 15q. HPV16 DNA integration or rearrangement correlated with CNAs in host cell DNA (P = 0.007). Although aCGH can resolve amplicons at the 1- to 2-megabase (Mb) regional resolution, the most common alteration on chromosome 3 could only be resolved to a 75-Mb region from 3q21 to qtel. Our data suggest that there may be several oncogenes in this region that are coactivated to contribute to progression to high-grade AIN.

Array-based comparative genomic hybridization reveals recurrent chromosomal aberrations and Jab1 as a potential target for 8q gain in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the major malignancies worldwide. We have previously characterized global gene expression patterns in HCC using microarrays. Here, we report the analysis of genomic DNA copy number among 49 HCC samples using BAC array-based comparative genomic hybridization (CGH). We observed recurrent and characteristic chromosomal aberrations, including frequent DNA copy number gains of 1q, 6p, 8q and 20q, and losses of 4q, 8p, 13q, 16q and 17p. We correlated gene expression with array CGH data, and identified a set of genes whose expression levels correlated with common chromosomal aberrations in HCC. Especially, we noticed that high expression of Jab1 in HCC significantly correlated with DNA copy number gain at 8q. Quantitative microsatellite analysis further confirmed DNA copy number gain at the Jab1 locus. Overexpression of Jab1 in HCC was also validated using real-time RT-PCR, and Jab1 protein levels were studied by immunohistochemistry on tissue microarrays. Functional analysis in HCC cell lines demonstrated that Jab1 may regulate HCC cell proliferation, thereby having a potential role in HCC development. In conclusion, this study shows that array-based CGH provides high resolution mapping of chromosomal aberrations in HCC, and demonstrates the feasibility of correlating array CGH data with gene expression data to identify novel oncogenes and tumor suppressor genes.

Ethnic and racial differences in prostate stromal estrogen receptor alpha.

BACKGROUND: Prostate cancer incidence and mortality rates vary widely among individuals of different ethnic/racial groups. We identified a relationship between a subset of genes and race/ethnicity using gene expression profiling. Estrogen receptor alpha (ERalpha) was selected for confirmation due to its plausible biological role in cancer susceptibility. METHODS: Quantitative polymerase chain reaction (Q-PCR) was used to verify gene expression results. Protein levels of ERalpha were determined by quantitative immunohistochemistry in a large-scale tissue microarray study (n = 183). RESULTS: ERalpha was significantly higher in stroma of Hispanic and Asian men than in Caucasian (P < 0.0001) and African American men (P < 0.0002), who are at higher risk for prostate cancer. In addition, large differences were seen in Q-PCR levels of ERalpha in prostate tissues of organ donors 16-29 years old who had no evidence of cancer. CONCLUSIONS: ERalpha exhibits variable expression in men of difference racial/ethnic background. Understanding the molecular basis for these differences may form the basis for prostate cancer prevention strategies with widespread public health impact.

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.

HOXB6 overexpression in murine bone marrow immortalizes a myelomonocytic precursor in vitro and causes hematopoietic stem cell expansion and acute myeloid leukemia in vivo.

The HOX family of homeobox genes plays an important role in normal and malignant hematopoiesis. Dysregulated HOX gene expression profoundly effects the proliferation and differentiation of hematopoietic stem cells (HSCs) and committed progenitors, and aberrant activation of HOX genes is a common event in human myeloid leukemia. HOXB6 is frequently overexpressed in human acute myeloid leukemia (AML). To gain further insight into the role of HOXB6 in hematopoiesis, we overexpressed HOXB6 in murine bone marrow using retrovirus-mediated gene transfer. We also explored structure-function relationships using mutant HOXB6 proteins unable to bind to DNA or a key HOX-binding partner, pre-B-cell leukemia transcription factor-1 (PBX1). Additionally, we investigated the potential cooperative interaction with myeloid ecotropic viral integration site 1 homolog (MEIS1). In vivo, HOXB6 expanded HSCs and myeloid precursors while inhibiting erythropoiesis and lymphopoiesis. Overexpression of HOXB6 resulted in AML with a median latency of 223 days. Coexpression of MEIS1 dramatically shortened the onset of AML. Cytogenetic analysis of a subset of HOXB6-induced AMLs revealed recurrent deletions of chromosome bands 2D-E4, a region frequently deleted in HOXA9-induced AMLs. In vitro, HOXB6 immortalized a factor-dependent myelomonocytic precursor capable of granulocytic and monocytic differentiation. These biologic effects of HOXB6 were largely dependent on DNA binding but independent of direct interaction with PBX1.

Id1 gene expression is up-regulated in hyperplastic and neoplastic thyroid tissue and regulates growth and differentiation in thyroid cancer cells.

The Id (inhibitor of DNA binding) proteins are a family of helix-loop-helix (HLH) proteins (Id1, Id2, Id3, and Id4) that lack the basic domain necessary for DNA binding. The Id1 protein enhances cell proliferation and inhibits cellular differentiation in a variety of cell types. We have previously demonstrated that the Id1 gene is up-regulated in papillary and medullary thyroid cancers. In this study we characterized the expression and distribution of the Id1 protein in normal, hyperplastic, and neoplastic human thyroid tissue. We also evaluated the effect of the Id1 gene on thyroid cancer cell growth and markers of thyroid cell differentiation. We used semiquantitative immunohistochemistry to characterize Id1 protein expression in normal, hyperplastic (multinodular goiter and Graves' disease), and neoplastic thyroid tissue from 103 patients. Normal thyroid tissue had the lowest level of Id1 protein expression (P < 0.0001). Anaplastic thyroid cancer had the highest level (vs. benign and malignant thyroid tissues, P < 0.01). Id1 protein expression was higher in malignant thyroid tissue than in hyperplastic thyroid tissue (P < 0.02). We found no significant association between the level of Id1 protein expression and patient age, sex, tumor-node-metastasis stage, tumor size, primary tumor vs. lymph node metastasis, primary tumor vs. recurrent tumors, and extent of tumor differentiation. Inhibiting Id1 mRNA expression in thyroid cancer cell lines using Id1 antisense oligonucleotides resulted in growth inhibition (P < 0.03) and decreased thyroglobulin and sodium-iodine symporter mRNA expression (P < 0.02). In conclusion, Id1 is overexpressed in hyperplastic and neoplastic thyroid tissue and directly regulates the growth of thyroid cancer cells of follicular cell origin, but is not a marker of aggressive phenotype in differentiated thyroid cancer.