Karen Woodson

The aryl hydrocarbon receptor repressor is a putative tumor suppressor gene in multiple human cancers

The aryl hydrocarbon receptor repressor (AHRR) is a bHLH/Per-ARNT-Sim transcription factor located in a region of chromosome 5 (5p15.3) that has been proposed to contain one or more tumor suppressor genes. We report here consistent downregulation of AHRR mRNA in human malignant tissue from different anatomical origins, including colon, breast, lung, stomach, cervix, and ovary, and demonstrate DNA hypermethylation as the regulatory mechanism of AHRR gene silencing. Knockdown of AHRR gene expression in a human lung cancer cell line using siRNA significantly enhanced in vitro anchorage-dependent and -independent cell growth as well as cell growth after transplantation into immunocompromised mice. In addition, knockdown of AHRR in non-clonable normal human mammary epithelial cells enabled them to grow in an anchorage-independent manner. Further, downregulation of AHRR expression in the human lung cancer cell line conferred resistance to apoptotic signals and enhanced motility and invasion in vitro and angiogenic potential in vivo. Ectopic expression of AHRR in tumor cells resulted in diminished anchorage-dependent and -independent cell growth and reduced angiogenic potential. These results therefore demonstrate that AHRR is a putative new tumor suppressor gene in multiple types of human cancers.

Manganese superoxide dismutase (MnSOD) polymorphism, α-tocopherol supplementation and prostate cancer risk in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (Finland)

Objective: Manganese superoxide dismutase (MnSOD) is a mitochondrial enzyme that plays a key role in protecting the cell from oxidative damage. A polymorphism in the mitochondrial targeting sequence (a valine to alanine substitution), thought to alter transport of the enzyme into mitochondria, has been associated with increased risk for breast cancer with a more pronounced association among women with low intake of dietary antioxidants. We examined the role of MnSOD in the development of prostate cancer in a large, randomized cancer prevention trial of male smokers, the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. We hypothesized that MnSOD may be associated with prostate cancer and that long-term antioxidant supplementation (α-tocopherol 50 mg/day for five to eight years) could modify the effect on risk. Methods: Logistic regression was used to estimate these associations among 197 cases and 190 controls genotyped and matched for age, intervention group, and clinic. Results: Men homozygous for the MnSOD ala allele had a 70% increase in risk over men homozygous for the val allele (odds ratio, OR = 1.72, 95% confidence interval, CI = 0.96–3.08, p = 0.07). Supplementation with α-tocopherol had no impact on the MnSOD–prostate cancer association. Although there was no difference in the association with disease stage, men homozygous for MnSOD ala (compared to MnSOD val/val or val/ala) showed a three-fold risk increase for high-grade tumors (OR = 2.72, 95% CI: 1.15–6.40, p = 0.02). Conclusion: These data suggest an effect of the MnSOD ala/ala genotype on the development of prostate cancer. Our observation of a stronger association with high-grade tumors may have prognostic implications that should also be pursued.

Analysis of Genes Critical for Growth Regulation Identifies Insulin-like Growth Factor 2 Receptor Variations with Possible Functional Significance as Risk Factors for Osteosarcoma

Background: Osteosarcoma, the most common malignant primary bone tumor, typically occurs during the adolescent growth spurt. Germ-line genetic variation in genes critical in growth regulation could confer altered risk of osteosarcoma. Methods: Fifty-two common single nucleotide polymorphisms (SNP) in 13 genes were genotyped in a prospective case-control study of osteosarcoma (104 osteosarcoma cases and 74 orthopedic controls). Genotype data analyzed with contingency tables suggested the strongest association with insulin-like growth factor 2 receptor (IGF2R) SNPs. Additional SNPs were genotyped to capture IGF2R common haplotypes and resequencing was done across the IGF2R block associated with osteosarcoma risk. Percentage methylation was determined by pyrosequencing of the IGF2R variant allele located in a CpG island. Results: IGF2R Ex16+88G>A (rs998075) and IVS16+15C>T (rs998074) SNPs were associated with increased risk for osteosarcoma compared with orthopedic controls (haplotype odds ratio, 2.04; 95% confidence interval, 1.29-3.24). Follow-up genotyping showed that IGF2R IVS15+213C>T was also associated with increased osteosarcoma risk. Resequence analysis identified two additional SNPs linked to the risk-associated SNPs; linkage disequilibrium was strongest in a 1-kb pair region around them. The Ex16+88G>A SNP is located within a CpG island and alters methylation at that site. Conclusion: This pilot study of germ-line genetic variation in growth pathway genes and osteosarcoma identified a haplotype block in IGF2R associated with increased risk of osteosarcoma. The presence of a SNP in this block results in loss of methylation at a CpG island, providing corroborative evidence of a possible functional variant. Our analysis of the IGF2R haplotype structure will be applicable to future studies of IGF2R and disease risk. (Cancer Epidemiol Biomarkers Prev 2007;16(8):1667–74)

Non-steroidal anti-inflammatory drug use is associated with reduction in recurrence of advanced and non-advanced colorectal adenomas (United States).

Objective: To prospectively examine the association between non-steroidal anti-inflammatory drugs (NSAIDs) use (including dose and dosage schedule) and the recurrence of colorectal adenomas among individuals who were diagnosed with an adenoma at entry into a clinical trial. Methods: For this analysis, participants who completed the full follow-up (n = 1905) for the Polyp Prevention Trial (PPT) were evaluated. Information on current use and dose of NSAIDs and other drugs was obtained at baseline and at each subsequent study visit over the duration of the trial. The study endpoint was the recurrence of colorectal adenomas in the 3 years between the 1-year trial colonoscopy (T1) and the end of the trial colonoscopy (T4). Results: There was a significant reduction in overall adenoma recurrence among NSAIDs users (odds ratio [OR] = 0.77; 95% confidence interval [CI]: 0.63–0.95), with the greatest effect seen in advanced polyps (OR = 0.51; CI: 0.33–0.79). Among aspirin users, we observed a significant dose response for overall adenoma recurrence, with a 40% reduction in the OR association (OR = 0.56; 95% CI: 0.31–0.99) among those taking more than 325 mg per day. Conclusion: This prospective study provides further evidence that NSAIDs may play an important role in the chemoprevention of recurrent colorectal adenomas, even those with advanced features.

Lack of association between serum levels of 25-hydroxyvitamin D and the subsequent risk of prostate cancer in Finnish men.

Ecologic studies support an inverse association between sunlight exposure and incidence of prostate cancer ([1][1]-[3][2]). Because sun exposure is the major source of human vitamin D production, several authors have hypothesized that the link between reduced prostate cancer incidence and increased

CD44 and PTGS2 methylation are independent prognostic markers for biochemical recurrence among prostate cancer patients with clinically localized disease.

Up to 30% of men with clinically localized disease who receive radical prostatectomy develop a biochemical recurrence. Gene methylation in tumor tissue may distinguish men with aggressive cancer. This study evaluated methylation of GSTP1, RARβ2, CD44 and PTGS2 with biochemical recurrence among 60 patients who underwent radical prostatectomy using logistic regression and Kaplan Meier time to event analysis. Methylation of GSTP1 and RARβ2 was not associated with recurrence, however, CD44 and PTGS2 methylation were significant predictors. In multivariate models adjusting for Gleason grade, methylation profile of CD44 and PTGS2 combined was an independent predictor of biochemical recurrence (associated with 9-fold increased risk). In addition, Kaplan Meier analysis showed CD44 and PTGS2 methylation was associated with shorter time to recurrence. CD44 and PTGS2 methylation may predict biochemical recurrence in prostate cancer patients undergoing radical prostatectomy and if validated in larger studies, may identify patients with aggressive cancer.

Analysis of a ribose transport operon from Bacillus subtilis

The csa-15 locus of Bacillus subtilis corresponds to an operon encoding proteins which display features characteristic of the ABC group of transporters. Sequence analysis reveals a very high level of identity to the ribose transport operon of Escherichia coli. This hypothesis is supported by the observation that strains carrying mutagenic insertions in this operon are unable to grow on ribose as sole carbon source. Expression of this operon is directed by a single SigA-type promoter which is negatively regulated by Spo0A during the late-exponential/transition state of the growth cycle. Expression is also subject to catabolite repression and this mode of regulation is dominant to control of expression by Spo0A.

Identification of a unique epigenetic sub-microenvironment in prostate cancer.

The glutathione S‐transferase P1 (GSTP1) gene promoter is methylated in tumour cells in more than 90% of prostate carcinomas. Recently, GSTP1 promoter methylation was identified in tumour‐associated stromal cells in addition to the tumour epithelium. To define the extent and location of stromal methylation, epigenetic mapping using pyrosequencing quantification of GSTP1 promoter methylation and an anatomical three‐dimensional reconstruction of an entire human prostate specimen with cancer were performed. Normal epithelium and stroma, tumour epithelium, and tumour‐associated stromal cells were laser capture‐microdissected from multiple locations throughout the gland. As expected, the GSTP1 promoter in both normal epithelium and normal stromal cells distant from the tumour was not methylated and the tumour epithelium showed consistently high levels of promoter methylation throughout. However, tumour‐associated stromal cells were found to be methylated only in a localized and distinct anatomical sub‐field of the tumour, revealing the presence of an epigenetically unique microenvironment within the cancer. Morphologically, the sub‐field consisted of typical, non‐reactive stroma, representing a genomic alteration in cells that appeared otherwise histologically normal. Similar epigenetic anatomical mapping of a control prostate gland without cancer showed low background methylation levels in all cell types throughout the specimen. These data suggest that stromal cell methylation can occur in a distinct sub‐region of prostate cancer and may have implications for understanding tumour biology and clinical intervention. Published in 2007 by John Wiley & Sons, Ltd.

Global Expression Analysis of Prostate Cancer-associated Stroma and Epithelia

Characterization of gene expression profiles in tumor cells and the tumor microenvironment is an important step in understanding neoplastic progression. To date, there are limited data available on expression changes that occur in the tumor-associated stroma as either a cause or consequence of cancer. In the present study, we employed a 54,000 target oligonucleotide microarray to compare expression profiles in the 4 major components of the microenvironment: tumor epithelium, tumor-associated stroma, normal epithelium, and normal stroma. Cells from 5 human, whole-mount prostatectomy specimens were microdissected and the extracted and amplified mRNA was hybridized to an Affymetrix Human Genome U133 Plus 2.0 GeneChip. Using the intersection of 2 analysis methods, we identified sets of differentially expressed genes among the 4 components. Forty-four genes were found to be consistently differentially expressed in the tumor-associated stroma; 35 were found in the tumor epithelium. Interestingly, the tumor-associated stroma showed a predominant up-regulation of transcripts compared with normal stroma, in sharp contrast to the overall down-regulation seen in the tumor epithelium relative to normal epithelium. These data provide insight into the molecular changes occurring in tumor-associated stromal cells and suggest new potential targets for future diagnostic, imaging, or therapeutic intervention.

The HIF-1alpha C1772T polymorphism may be associated with susceptibility to clinically localised prostate cancer but not with elevated expression of hypoxic biomarkers.

We investigated the role of the C1772T polymorphisms in exon 12 of the Hypoxia-inducible factor-1 alpha (HIF-1α) gene C1772T genotype in prostate cancer (PCa) and amplification of the hypoxic response. We identified the heterozygous germline CT genotype as an increased risk factor for clinically localised prostate cancer (Odds ratio=6.2; p