Hyun Y. Park

miR-21, miR-221 and miR-222 expression and prostate cancer recurrence among obese and non-obese cases.

Recent evidence shows that certain microRNAs (miRNAs) play a role in both obesity and prostate cancer recurrence, but the association between the expression of these miRNAs and obesity in prostate cancer recurrence is unknown. In this study, we examined the effect of the interaction between obesity and miR-21, miR-221 or miR-222 expression on prostate cancer recurrence among 28 recurrent and 37 non-recurrent prostate cancer cases. miRNA expression was determined using quantitative real-time polymerase chain reaction. Cox proportional hazard models adjusting for age at diagnosis, clinical stage and Gleason score were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for recurrence free survival. A significantly (P=0.014) higher proportion of recurrent cases (78.6%) than non-recurrent cases (48.6%) had a low expression of miR-21 and the difference was more prominent in obese than non-obese patients. Multivariate analysis showed that the expression of miR-21 was an independent risk factor for recurrence in obese (HR=6.15, 95% CI=1.04-36.48, P=0.045), but not in non-obese (HR=1.28, 95% CI=0.30-5.49, P=0.74) cases. A significant association with recurrence was not observed for the expression of miR-221 and miR-222. In summary, our findings show that miR-21 is associated with prostate cancer recurrence after radical prostatectomy and suggest that the differential expression of miR-21 is more prominent in obese than in non-obese cases. Future larger studies are warranted to confirm these initial findings and to elucidate the mechanisms involved.

Safety and Chemopreventive Effect of Polyphenon E in Preventing Early and Metastatic Progression of Prostate Cancer in TRAMP Mice

Prostate cancer treatment is often accompanied by untoward side effects. Therefore, chemoprevention to reduce the risk and inhibit the progression of prostate cancer may be an effective approach to reducing disease burden. We investigated the safety and efficacy of Polyphenon E, a green tea extract, in reducing the progression of prostate cancer in transgenic adenocarcinoma of the mouse prostate (TRAMP) mice. A total of 119 male TRAMP and 119 C57BL/6J mice were treated orally with one of 3 doses of Polyphenon E (200, 500, and 1,000 mg/kg/day) in drinking water ad libitum replicating human achievable doses. Baseline assessments were performed before treatments. Safety and efficacy assessments during treatments were performed when mice were 12, 22, and 32 weeks old. The number and size of tumors in treated TRAMP mice were significantly decreased compared with untreated animals. In untreated 32 weeks old TRAMP mice, prostate carcinoma metastasis to distant sites was observed in 100% of mice (8/8), compared with 13% of mice (2/16) treated with high-dose Polyphenon E during the same period. Furthermore, Polyphenon E treatment significantly inhibited metastasis in TRAMP mice in a dose-dependent manner (P = 0.0003). Long-term (32 weeks) treatment with Polyphenon E was safe and well tolerated with no evidence of toxicity in C57BL/6J mice. Polyphenon E is an effective chemopreventive agent in preventing the progression of prostate cancer to metastasis in TRAMP mice. Polyphenon E showed no toxicity in these mouse models. Our findings provide additional evidence for the safety and chemopreventive effect of Polyphenon E in preventing metastatic progression of prostate cancer. Cancer Prev Res; 7(4); 435–44. ©2014 AACR.

Gene silencing of SLC5A8 identified by genome-wide methylation profiling in lung cancer

BACKGROUND Aberrant DNA hypermethylation has been implicated as a component of an epigenetic mechanism that silences genes in cancers. METHODS We performed a genome-wide search to identify differentially methylated loci between 26 tumor and adjacent non-tumor paired tissues from same lung cancer patients using restriction landmark genomic scanning (RLGS) analysis. Among 229 loci which were hypermethylated in lung tumors as compared to adjacent non-tumor tissues, solute carrier family 5, member 8 (SLC5A8) was one of the hypermethylated genes, and known as a tumor suppressor gene which is silenced by epigenetic changes in various tumors. We investigated the significance of DNA methylation in SLC5A8 expression in lung cancer cell lines, and 23 paired tumor and adjacent non-tumor lung tissues by reverse transcription-PCR (RT-PCR), quantitative methylation specific PCR (QMSP) and bisulfite modified DNA sequencing analyses. RESULTS Reduced or lost expression of SLC5A8 was observed in 39.1% (9/23) of the tumor tissues as compared with paired adjacent non-tumor tissues. Bisulfite sequencing results of lung cancer cell lines and tissues which did not express SLC5A8 showed a densely methylated promoter region of SLC5A8. SLC5A8 was reactivated by treatment with DNA methyltransferase inhibitor, 5-Aza and/or HDAC inhibitor, trichostatin A (TSA) in lung cancer cell lines, which did not express SLC5A8. Hypermethylation was detected at the promoter region of SLC5A8 in primary lung tumor tissues as compared with adjacent non-tumor tissues (14/23, 60.9%). CONCLUSION These results suggest that DNA methylation in the SLC5A8 promoter region may suppress the expression of SLC5A8 in lung tumor.

Gene Variants in Angiogenesis and Lymphangiogenesis and Cutaneous Melanoma Progression

Background: Angiogenesis and lymphangiogenesis are important in the progression of melanoma. We investigated associations between genetic variants in these pathways with sentinel lymph node (SLN) metastasis and mortality in 2 independent series of patients with melanoma. Methods: Participants at Moffitt Cancer Center were 552 patients, all Caucasian, with primary cutaneous melanoma referred for SLN biopsy. A total of 177 patients had SLN metastasis, among whom 60 died from melanoma. Associations between 238 single-nucleotide polymorphisms (SNP) in 26 genes and SLN metastasis were estimated as ORs and 95% confidence intervals (CI) using logistic regression. Competing risk regression was used to estimate HRs and 95% CI for each SNP and melanoma-specific mortality. We attempted to replicate significant findings using data from a genome-wide association study comprising 1,115 patients with melanoma who were referred for SLN biopsy from MD Anderson Cancer Center (MDACC), among whom 189 patients had SLN metastasis and 92 patients died from melanoma. Results: In the Moffitt dataset, we observed significant associations in 18 SNPs with SLN metastasis and 17 SNPs with mortality. Multiple SNPs in COL18A1, EGF receptor (EGFR), FLT1, interleukin (IL)-10, platelet-derived growth factor D (PDGFD), PIK3CA, and toll-like receptor (TLR)-3 were associated with the risk of SLN metastasis and/or patient mortality. The MDACC data set replicated an association between mortality and rs2220377 in PDGFD. Furthermore, in a meta-analysis, 3 additional SNPs were significantly associated with SLN metastasis (EGFR rs723526 and TLR3 rs3775292) and melanoma-specific death (TLR3 rs7668666). Conclusions: These findings suggest that genetic variation in angiogenesis and lymphangiogenesis contributes to regional nodal metastasis and progression of melanoma. Impact: Additional research attempting to replicate these results is warranted. Cancer Epidemiol Biomarkers Prev; 22(5); 827–34. ©2013 AACR.

Metal ion binding and activation of Streptomyces griseus dinuclear aminopeptidase: cadmium(II) binding as a model.

Abstract. A detailed metal binding and activation of the dinuclear aminopeptidase from Streptomyces griseus (sAP) has been analyzed and modeled by means of metal titration as well as kinetic and thermodynamic techniques using Cd2+ as a probe. Cd2+ binds to the two metal-binding sites in a sequential manner to produce a very active Cd2+-substituted derivative, particularly in the presence of Ca2+ (53% and 90%, respectively, relative to the activities of the native form in terms of kcat/Km under the same conditions). The first stepwise formation constant for the binding of metal to the dinuclear site (to form M-sAP) was found to determine the metal-binding selectivity, regardless of the magnitude of the second stepwise formation constant (to form M,M-sAP from M-sAP). Interestingly, despite the seemingly very different binding profiles for different metal ions under different conditions, all of them can be well described and fitted by the sequential binding model. In addition, Ca2+ was found to significantly affect metal binding, inhibition, and entropy of activation of this enzyme, and its role in sAP action is re-evaluated.

Role of p73 Dinucleotide Polymorphism in Prostate Cancer and p73 Protein Isoform Balance.

Background. Molecular markers for prostate cancer (PCa) risks are currently lacking. Here we address the potential association of a dinucleotide polymorphism (DNP) in exon 2 of the p73 gene with PCa risk/progression and discern any disruption of p73 protein isoforms levels in cells harboring a p73 DNP allele. Methods. We investigated the association between p73 DNP genotype and PCa risk/aggressiveness and survival by fitting logistic regression models in 1,292 incident cases and 682 controls. Results. Although we detected no association between p73 DNP and PCa risk, a significant inverse relationship between p73 DNP and PCa aggressiveness (AT/AT + GC/AT versus GC/GC, OR = 0.55, 95%Cl = 0.31–0.99) was detected. Also, p73 DNP is marginally associated with overall death (dominant model, HR = 0.76, 95%Cl = 0.57–1.00, P = 0.053) as well as PCa specific death (HR = 0.69, 95%Cl = 0.45–1.06, P = 0.09). Western blot analyses for p73 protein isoforms indicate that cells heterozygous for the p73 DNP have lower levels of ∆Np73 relative to TAp73 (P < 0.001). Conclusions. Our findings are consistent with an association between p73 DNP and low risk for PCa aggressiveness by increasing the expressed TAp73/∆Np73 protein isoform ratio.

Height, selected genetic markers and prostate cancer risk: results from the PRACTICAL consortium.

Background:Evidence on height and prostate cancer risk is mixed, however, recent studies with large data sets support a possible role for its association with the risk of aggressive prostate cancer.Methods:We analysed data from the PRACTICAL consortium consisting of 6207 prostate cancer cases and 6016 controls and a subset of high grade cases (2480 cases). We explored height, polymorphisms in genes related to growth processes as main effects and their possible interactions.Results:The results suggest that height is associated with high-grade prostate cancer risk. Men with height >180 cm are at a 22% increased risk as compared to men with height <173 cm (OR 1.22, 95% CI 1.01–1.48). Genetic variants in the growth pathway gene showed an association with prostate cancer risk. The aggregate scores of the selected variants identified a significantly increased risk of overall prostate cancer and high-grade prostate cancer by 13% and 15%, respectively, in the highest score group as compared to lowest score group.Conclusions:There was no evidence of gene-environment interaction between height and the selected candidate SNPs.Our findings suggest a role of height in high-grade prostate cancer. The effect of genetic variants in the genes related to growth is seen in all cases and high-grade prostate cancer. There is no interaction between these two exposures.Background: Evidence on height and prostate cancer risk is mixed, however, recent studies with large data sets support a possible role for its association with the risk of aggressive prostate cancer. Methods: We analysed data from the PRACTICAL consortium consisting of 6207 prostate cancer cases and 6016 controls and a subset of high grade cases (2480 cases). We explored height, polymorphisms in genes related to growth processes as main effects and their possible interactions. Results: The results suggest that height is associated with high-grade prostate cancer risk. Men with height >180 cm are at a 22% increased risk as compared to men with height <173 cm (OR 1.22, 95% CI 1.01–1.48). Genetic variants in the growth pathway gene showed an association with prostate cancer risk. The aggregate scores of the selected variants identified a significantly increased risk of overall prostate cancer and high-grade prostate cancer by 13% and 15%, respectively, in the highest score group as compared to lowest score group. Conclusions: There was no evidence of gene-environment interaction between height and the selected candidate SNPs. Our findings suggest a role of height in high-grade prostate cancer. The effect of genetic variants in the genes related to growth is seen in all cases and high-grade prostate cancer. There is no interaction between these two exposures.

Abstract 5569: p73 dinucleotide polymorphism genotyping of human cancer cell lines

The p73 gene is a member of the p53 tumor suppressor family. The p73 dinucleotide polymorphism (DNP) (rs1801173) is a G4C14-to-A4T14 linked pair of transitions located in exon 2 between the P1 and P2 gene promoters. The P1 and P2 p73 gene promoters are the transcription initiation sites for mRNAs encoding TAp73 and ΔNp73 isoforms, respectively. Recently, we reported the p73 DNP allele was associated with (1) decreased risk [OR = 0.55, 95%CI = 0.31-0.99] for aggressive prostate cancer (PCa) and (2) increased TAp73/ΔNp73 protein isoform ratios in ten human cancer cell lines. We hypothesize the presence of the p73 DNP allele causes altered p73 promoter usage resulting in increased TAp73/ΔNp73 protein isoform ratios, which could explain the observed decreased risk for PCa aggressiveness. Our ultimate goal is to assess the potential of p73 DNP as a biomarker for lower aggressive PCa risk. Therefore, our initial aim in this study was to determine the p73 DNP genotype in ten additional human cancer cell lines (DU 145, JEG-3, K-562, LNCaP, MDA-MB-231, MDA-MB-468, MRC-5, PC-3, SW48 and U-2OS) not yet characterized for p73 DNP status. We previously reported the p73 DNP genotype of three human cancer cell lines that we used as genotyping controls: Caco-2 (homozygous polymorphic), NCI-H1299 (homozygous wild type), and HepG2 (heterozygous). Cell lines were cultured and genomic DNA was isolated and quantitated. Cell line genomic DNA samples were used in TaqMan Real Time-PCR allelic discrimination assays to determine the p73 DNP genotypes. Our data conclusively determined that DU 145, JEG-3, K-562, LNCaP, MDA-MB-468, MRC-5, SW48 and U-2OS were p73 DNP homozygous wild type, while PC-3 and MDA-MB-231 werw p73 DNP heterozygous. Citation Format: L. Michael Carastro, Kaia K. Hampton, Ricardo A. Cordova Estupinan, Hyun Y. Park, Dongwha Kim, Jong Y. Park. p73 dinucleotide polymorphism genotyping of human cancer cell lines. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5569. doi:10.1158/1538-7445.AM2015-5569

Abstract 5070: Role of p73 di-nucleotide polymorphism in prostate cancer and p73 protein isoform balance

The p73 gene is a member of the p53 tumor suppressor family. Compared to p53, the molecular consequences of and risk factors associated with variants of the p73 gene are not well understood. Prostate cancer (PCa) is the most frequently occurring cancer in men, and the second leading cause of cancer mortality among US men. Available molecular markers for PCa risk of incidence or aggressiveness are currently lacking. Though the mechanism of PCa progression is not well understood, several lines of evidence support a role for a di-nucleotide polymorphism (DNP) in the p73 gene as a risk factor for several cancer types. However, results are inconsistent. We investigated a DNP linked pair of transition changes, G4C14-to-A4T14 (rs1801173), located in the 5′-UTR portion of exon 2 of the p73 gene. The goals of this study were to address the potential associations between p73 DNP (rs1801173) and PCa risk and/or progression, and to discern any detectable disruption of p73 protein isoforms in cells harboring the p73 DNP allele. We have analyzed 1,292 PCa patients and 682 healthy control men. Although we detected no association between p73 DNP and PCa risk (OR =1.02, 95%CI=0.86-1.21), a significant inverse relationship between p73 DNP and PCa aggressiveness (OR = 0.55, 95%CI=0.31-0.99) was detected. Several p73 protein isoforms have been identified and can be grouped into two major categories, TAp73 and ΔNp73, which differ in their N-termini and are transcribed from different promoters. The transcriptionally active TAp73 isoforms are transcribed from the P1 promoter and include the full-length N-terminal sequence encompassing exons 1 through 3. However, the ΔNp73 isoforms are transcribed from promoter P2 and do not contain the N-terminal trans-activation (TA) domain. Therefore, the ΔNp73 protein isoform is dominate negative toward TAp73 because ΔNp73 isoforms are able to form tetramers with TAp73, as well as p53, but do not activate transcription of p73- or p53-target genes. The balance between TAp73 and ΔNp73 is disrupted in many cancer types. In this study, Western Blot analyses of eleven cancer cell lines for p73 protein isoforms indicate that the two cell lines with heterozygous genotype for p73 DNP have higher TAp73/ΔNp73 ratios (TAp73/ΔNp73 = 1.39 and 1.4) than the other wild-type cell lines not harboring the p73 DNP allele (TAp73/ΔNp73 = 0.68 to 0.97). Our combined findings are consistent with an association between the p73 DNP allele and lower risk for PCa aggressiveness by increasing the expressed TAp73/ΔNp73 protein isoform ratio. Citation Format: L. Michael Carastro, Hui-Yi Lin, Hyun Y. Park, Donghwa Kim, Selina Radlein, Kaia K. Hampton, Ardeshir Hakam, Babu Zachariah, Julio M. Pow-Sang, Jong Y. Park. Role of p73 di-nucleotide polymorphism in prostate cancer and p73 protein isoform balance. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5070. doi:10.1158/1538-7445.AM2014-5070

Abstract 2851: Genetic polymorphisms and expression of SLC5A8 in prostate cancer

Prostate cancer is the most common cancer in men, comprising approximately one-third of all male-specific cancers. SLC5A8 is a sodium-coupled transporter for short-chain fatty acids which are known to induce apoptosis by histone deacetylase inhibition. Previous studies suggest that SLC5A8 may function as a tumor suppressor gene whose silencing by epigenetic changes may contribute to carcinogenesis. For this reason, we investigated the role of expression and single nucleotide polymorphisms (SNPs) of SLC5A8 in prostate cancer risk and aggressiveness. We examined the association between common polymorphisms and risk for prostate cancer using a case-control study with 587 patients with incident primary prostate cancer, recruited at the Moffitt Cancer Center, and the James Haley VA Hospital and 347 age-matched controls, who were visiting the Lifetime Cancer Screening Center, which is affiliated with the Moffitt Cancer Center. All control subjects were male and had no previous diagnosis of cancer. We genotyped each study subject9s DNA for four SNPs (rs164365, rs1709189, rs1399236, and rs1681096) in SLC5A8, by the TaqMan analysis. The frequencies of these SNPs were compared between cases and controls using logistic regression. Genotype distributions of all candidate SNPs in the controls followed Hardy-Weinberg equilibrium. In addition, SLC5A8 protein expression was estimated using innmunostained tissue microarray constructed from prostate tumor and normal tissues from BPH patients. We derived a semi-quantitative assessment by multiplying immunostain intensity and percentage of cells stained (range=0-9). We collected 140 prostate tumor tissues and 43 pairs of tumor and adjacent normal tissues from prostate cancer patients. From controls and BPH patients, 56 normal tissues were obtained. Among 43 pairs of tumor and normal tissues, SLC5A8 expression was significantly higher in tumor tissues than in their adjacent normal tissues (p Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2851.