Zinc Intake and Risk of Prostate Cancer: Case-Control Study and Meta-Analysis

Zinc is an essential dietary element that has been implicated in the pathogenesis of prostate cancer, a cancer that disproportionately affects men of African descent. Studies assessing the association of zinc intake and prostate cancer have yielded inconsistent results. Furthermore, very little is known about the relationship between zinc intake and prostate cancer among African Americans. We examined the association between self-reported zinc intake and prostate cancer in a hospital-based case-control study of African Americans. We then compared our results with previous studies by performing a meta-analysis to summarize the evidence regarding the association between zinc and prostate cancer. Newly diagnosed African American men with histologically confirmed prostate cancer (n = 127) and controls (n = 81) were recruited from an urban academic urology clinic in Washington, DC. Controls had higher zinc intake, with a mean of 14 mg/day versus 11 mg/day for cases. We observed a non-significant, non-linear increase in prostate cancer when comparing tertiles of zinc intake (OR _{<6.5 vs 6.5–12.5mg/day} 1.8, 95% CI: 0.6,5.6; OR _{<6.5 vs >12.5mg/day} 1.3, 95% CI: 0.2,6.5). The pooled estimate from 17 studies (including 3 cohorts, 2 nested case-control, 11 case-control studies, and 1 randomized clinical trial, with a total of 111,199 participants and 11,689 cases of prostate cancer) was 1.07_{hi vs lo} 95% CI: 0.98–1.16. Using a dose-response meta-analysis, we observed a non-linear trend in the relationship between zinc intake and prostate cancer (p for nonlinearity = 0.0022). This is the first study to examine the relationship between zinc intake in black men and risk of prostate cancer and systematically evaluate available epidemiologic evidence about the magnitude of the relationship between zinc intake and prostate cancer. Despite of the lower intake of zinc by prostate cancer patients, our meta-analysis indicated that there is no evidence for an association between zinc intake and prostate cancer.     

Downstream of tyrosine kinases-1 and Src homology 2-containing inositol 5'-phosphatase are required for regulation of CD4+CD25+ T cell development

The adaptor protein, downstream of tyrosine kinases-1 (Dok-1), and the phosphatase SHIP are both tyrosine phosphorylated in response to T cell stimulation. However, a function for these molecules in T cell development has not been defined. To clarify the role of Dok-1 and SHIP in T cell development in vivo, we compared the T cell phenotype of wild-type, Dok-1 knockout (KO), SHIP KO, and Dok-1/SHIP double-knockout (DKO) mice. Dok-1/SHIP DKO mice were runted and had a shorter life span compared with either Dok-1 KO or SHIP KO mice. Thymocyte numbers from Dok-1/SHIP DKO mice were reduced by 90%. Surface expression of both CD25 and CD69 was elevated on freshly isolated splenic CD4(+) T cells from SHIP KO and Dok-1/SHIP DKO, suggesting these cells were constitutively activated. However, these T cells did not proliferate or produce IL-2 after stimulation. Interestingly, the CD4(+) T cells from SHIP KO and Dok-1/SHIP DKO mice produced higher levels of TGF-beta, expressed Foxp3, and inhibited IL-2 production by CD3-stimulated CD4(+)CD25(-) T cells in vitro. These findings suggest Dok-1 and SHIP function in pathways that influence regulatory T cell development.     

Identification of hepsin and protein disulfide isomerase A3 as targets of gelatinolytic action in rat ovarian granulosa cells during the periovulatory period

The matrix metalloproteinase (MMP) family is believed to play a role in the ovulatory process because MMP inhibitors block oocyte release. However, little is known about the mechanisms by which the MMPs affect ovulation. The present study investigated the degradomic actions of the gelatinases, MMP2 and MMP9, by identifying gelatinolytic targets in periovulatory granulosa cells. Granulosa cells were collected from immature rats 48 h after equine chorionic gonadotropin treatment and were cultured with human chorionic gonadotropin (hCG) in the absence or presence of a specific MMP2/9 inhibitor ((2R)-2-[(4-biphenylylsulfonyl)amino]-3-phenylpropionic acid) for an additional 24 h. The conditioned media was analyzed for gelatinolytic activity, progesterone, and peptide profiles. Gelatinolytic activity and progesterone were induced in response to hCG; however, there was no difference in progesterone between cells treated with or without the inhibitor. Peptide fragments of proteins altered in the presence of the gelatinase inhibitor were identified by two-dimensional gel electrophoresis and mass spectrometry. Protein disulfide isomerase A3 (PDIA3), which plays a role in protein folding, was identified as a peptide that decreased in the presence of inhibitor while the serine protease hepsin, was found to increase with inhibitor treatment. Subsequent experiments established that PDIA3 and hepsin were targets of MMP2/9 action by cleavage with MMP2 and Western blot analysis, respectively. Additionally, hepsin was identified as a gelatinolytic target in ovarian cancer cells. In the present study, proteomics has identified proteins that may be involved in novel ways in the complex cascades that are mediated by gelatinolytic MMPs during the periovulatory period.     

Specific thiazolidinediones inhibit ovarian cancer cell line proliferation and cause cell cycle arrest in a PPARγ independent manner

Background

Peroxisome Proliferator Activated Receptor gamma (PPARγ) agonists, such as the thiazolinediones (TZDs), have been studied for their potential use as cancer therapeutic agents. We investigated the effect of four TZDs—Rosiglitazone (Rosi), Ciglitazone (CGZ), Troglitazone (TGZ), and Pioglitazone (Pio)—on ovarian cancer cell proliferation, PPARγ expression and PPAR luciferase reporter activity. We explored whether TZDs act in a PPARγ dependent or independent manner by utilizing molecular approaches to inhibit or overexpress PPARγ activity.

Principal Findings

Treatment with CGZ or TGZ for 24 hours decreased proliferation in three ovarian cancer cell lines, Ovcar3, CaOv3, and Skov3, whereas Rosi and Pio had no effect. This decrease in Ovcar3 cell proliferation was due to a higher fraction of cells in the G₀/G₁ stage of the cell cycle. CGZ and TGZ treatment increased apoptosis after 4 hours of treatment but not after 8 or 12 hours. Treatment with TGZ or CGZ increased PPARγ mRNA expression in Ovcar3 cells; however, protein levels were unchanged. Surprisingly, luciferase promoter assays revealed that none of the TZDs increased PPARγ activity. Overexpression of wild type PPARγ increased reporter activity. This was further augmented by TGZ, Rosi, and Pio indicating that these cells have the endogenous capacity to mediate PPARγ transactivation. To determine whether PPARγ mediates the TZD-induced decrease in proliferation, cells were treated with CGZ or TGZ in the absence or presence of a dominant negative (DN) or wild type overexpression PPARγ construct. Neither vector changed the TZD-mediated cell proliferation suggesting this effect of TZDs on ovarian cancer cells may be PPARγ independent.

Conclusions

CGZ and TGZ cause a decrease in ovarian cancer cell proliferation that is PPARγ independent. This concept is supported by the finding that a DN or overexpression of the wild type PPARγ did not affect the changes in cell proliferation and cell cycle.     

Associations between functional polymorphisms in antioxidant defense genes and urinary oxidative stress biomarkers in healthy, premenopausal women

Functional polymorphisms in endogenous antioxidant defense genes including manganese superoxide dismutase (MnSOD), catalase (CAT), and glutathione peroxidase (GPX-1) have been linked with risk of cancer at multiple sites. Although it is presumed that these germline variants impact disease risk by altering the host’s ability to detoxify mutagenic reactive oxygen species, very few studies have directly examined this hypothesis. Concentrations of 8-isoprostane F2α (8-iso-PGF2α) and 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxoxdG)—sensitive indicators of lipid peroxidation and DNA oxidation, respectively—were measured in 24-h urine samples obtained from 93 healthy, premenopausal women participating in a dietary intervention trial. In addition, DNA was extracted from blood for genotyping of MnSOD Val16Ala, CAT-262 C > T, and GPX1 Pro198Leu genotypes by Taqman assay. Although geometric mean concentrations of 8-iso-PGF2_α and 8-oxoxdG varied across several study characteristics including race, education level, body mass index, and serum antioxidant levels, there was little evidence that these biomarkers differed across any of the examined genotypes. In summary, functional polymorphisms in endogenous antioxidant defense genes do not appear to be strongly associated with systemic oxidative stress levels in young, healthy women.     

Association of Genetic Ancestry with Breast Cancer in Ethnically Diverse Women from Chicago

Introduction

Non-Hispanic (nH) Black and Hispanic women are disproportionately affected by early onset disease, later stage, and with more aggressive, higher grade and ER/PR negative breast cancers. The purpose of this analysis was to examine whether genetic ancestry could account for these variation in breast cancer characteristics, once data were stratified by self-reported race/ethnicity and adjusted for potential confounding by social and behavioral factors.

Methods

We used a panel of 100 ancestry informative markers (AIMs) to estimate individual genetic ancestry in 656 women from the “Breast Cancer Care in Chicago” study, a multi-ethnic cohort of breast cancer patients to examine the association between individual genetic ancestry and breast cancer characteristics. In addition we examined the association of individual AIMs and breast cancer to identify genes/regions that may potentially play a role in breast cancer disease disparities.

Results

As expected, nH Black and Hispanic patients were more likely than nH White patients to be diagnosed at later stages, with higher grade, and with ER/PR negative tumors. Higher European genetic ancestry was protective against later stage at diagnosis (OR 0.7 95%CI: 0.54–0.92) among Hispanic patients, and higher grade (OR 0.73, 95%CI: 0.56–0.95) among nH Black patients. After adjustment for multiple social and behavioral risk factors, the association with later stage remained, while the association with grade was not significant. We also found that the AIM SNP rs10954631 on chromosome 7 was associated with later stage (p = 0.02) and higher grade (p = 0.012) in nH Whites and later stage (p = 0.03) in nH Blacks.

Conclusion

Non-European genetic ancestry was associated with later stage at diagnosis in ethnic minorities. The relation between genetic ancestry and stage at diagnosis may be due to genetic factors and/or unmeasured environmental factors that are overrepresented within certain racial/ethnic groups.