1 03-forszt.qxd 7/10/09 12:33 PM Page 215 ORIGINAL PAPERS Adv Clin Exp Med 2009, 18, 3, ISSN X Copyright by Wroclaw Medical University PATRIK FORSZT 1, AGNIESZKA PILECKA 2, 3, MAŁGORZATA MAŁODOBRA 2, 4, JOANNA MARKOWSKA 3, KRZYSZTOF MAKSYMOWICZ 3, TADEUSZ DOBOSZ 2 Single Nucleotide Polymorphism Association Study of VDR and CDH1 Genes and the Risk of Prostate Cancer Wpływ polimorfizmu typu SNP w genach VDR i CDH1 na ryzyko rozwoju raka prostaty 1 Regional Specialist Hospital, Research and Development Center, Wroclaw, Poland 2 Department of Forensic Medicine, Molecular Technique Unit, Wroclaw Medical University, Wroclaw, Poland 3 Department and Unit of Forensic Medicine, Wroclaw Medical University, Wroclaw, Poland 4 Warsaw University of Medicine, Postgraduate School of Molecular Medicine, Warsaw, Poland Abstract Background. Prostate cancer (PC) is considered the most common cause of male cancer mortality. A positive fam ily history is one of the strongest risk factors for prostate cancer. Numerous data indicate that PC has a genetic background; however, it cannot be explained as a single gene disease but as a multigenetic disorder. Objectives. The aim of this study was to search for genetic correlation between single nucleotide polymorphisms (SNPs) in the VDR and CDH1 genes and the risk of PC. Material and Methods. One hundred PC patients and 100 control subjects were investigated. The SNPs rs and rs in VDR and rs16260 in CDH1 were detected by minisequencing followed by capillary electrophoresis. Hardy Weinberg equilibrium, the chi squared test, and non parametric tests (Wald Wolfowitz and Mann Whitney U) were used for statistical analyses. Results. Two of the three tested SNPs, i.e. rs in VDR and rs16260 in CDH1, displayed statistically sig nificant differences in frequency between the two groups (p = and p = for rs and rs16260, respectively). The C/C genotype of rs in VDR gene positively correlated with increased prostrate specific antigen (PSA) level (p = ). Conclusions. The results provide unique data and show strong association between the tested SNPs in the VDR and CDH1 genes and malignancy and progression of prostate cancer (Adv Clin Exp Med 2009, 18, 3, ). Key words: prostate cancer, SNP, VDR gene, CDH1 gene. Streszczenie Wprowadzenie. Rak prostaty (r.p.) jest obecnie jedną z najczęstszych przyczyn śmierci z powodu nowotworów wśród mężczyzn. Jednym z czynników ryzyka jest wywiad rodzinny w kierunku raka prostaty. Wiele danych prze mawia za tym, iż r.p. ma podłoże genetyczne o wielogenowym charakterze dziedziczenia. Cel pracy. Poszukiwanie korelacji między polimorfizmem typu SNP w genach VDR i CDH1 a ryzykiem rozwoju raka prostaty. Materiał i metody. Zbadano 100 pacjentów z rakiem prostaty oraz 100 zdrowych mężczyzn w podobnym przedziale wiekowym. Analizie poddano rs oraz rs znajdujące się w genie VDR oraz rs16260 w genie CDH1. Uzyskane wyniki poddano analizie statystycznej z zastosowaniem testu χ 2 oraz testów niepara metrycznych (Wald Wolfowitza i U Mann Whitneya). Wyniki. Dwa z trzech analizowanych polimorfizmów: rs w genie VDR oraz rs16260 w genie CDH1 wykazało istotne statystycznie różnice w częstości występowania między badanymi grupami (p = 0,0266 i p = 0,0123 dla rs i rs16260, odpowiednio). Poza tym genotyp C/C rs dodatnio korelował z podwyższonym poziomem PSA u chorych (p = 0,0073). Wnioski. W przestawionej pracy wykazano korelację między polimorfizmami w genach VDR i CDH1 a rozwojem raka prostaty wśród pacjentów z regionu Dolnego Śląska (Adv Clin Exp Med 2009, 18, 3, ). Słowa kluczowe: rak prostaty, polimorfizm typu SNP, VDR, CDH1.
2 03-forszt.qxd 7/10/09 12:33 PM Page Prostate cancer (PC) is considered, after lung cancer, the most common cause of male cancer mortality . The mechanism of its pathogenesis is still unknown; however, the risk factors are well known, one of the strongest being a positive fami ly history of prostate cancer. Approximately 10 15% of men with prostate cancer have at least one relative who is also affected. Steinberg et al.  estimated that the risk of prostate cancer rises by a factor of two for patients with a positive fam ily history and by five with more than one affect ed first degree relatives. This suggests that PC has a genetic background; however, it cannot be explained as a single gene disease, but rather as a multigenetic disorder [3, 4]. The list of candidate genes correlating with prostate cancer covers many, including genes implicated in testosterone biosynthesis, degradation, and distribution . Cancer is defined as uncontrolled cell prolifera tion; therefore genes controlling cell differentia tion and proliferation were selected as candidate genes for PC in this study. The role of vitamin D receptor (VDR) in cell proliferation and differentiation was established over 20 years ago . There is strong evidence for correlation of variations in VDR gene with many types of cancer, including breast, renal, colon, and PC . Some variations, such as single nucleotide polymorphisms (SNPs) and STR polymorphisms, have been related to increased PC risk in numer ous studies in various populations [7 11]; howev er, the results provided discrete data. The E cad herin gene (CDH1), encoding a transmembrane glycoprotein which mediates cell cell adhesion and signaling , has been recently associated with increased risk of PC. It has been shown that impaired expression of CDH1 resulted in prostate cancer metastasis and progression and poor prog nosis . According to Hoogerdoorn et al. , SNPs in the promoter region might influence the level of expression. Changes in the promoter region of CDH1 can lead to a disruption of cell adhesion and signaling and finally to cancerogen esis. Therefore we investigated SNP in the pro moter region of CDH1 gene to evaluate its associ ation with prostate cancer. The aim of this study was to search for genet ic correlation between SNPs in the VDR and CDH1 genes and the risk of prostate cancer in a Lower Silesian population. The results were also compared with those obtained by others authors to confirm or reject an association with PC. Material and Methods Study Population SNP genotyping was performed on 100 patients diagnosed with PC treated at the Regional Specialist Hospital, Research and Development Center, Wroclaw. The mean age of the PC patients was 75 ± 7.6 years and the mean prostate specific antigen (PSA) level was 40 ± 55 ng/ml. Genetic material of 100 control subjects came from the DNA bank of the Molecular Technique Unit, Wroclaw Medical University, representing a broad male population from the Lower Silesian region undergoing paternity tests. The cancer patients and control subjects were unrelated. The study was approved by the Ethics Committee and conformed to the ethical standards of the Declaration of Helsinki. Genotyping P. FORSZT et al. Genetic material of the PC patients was isolat ed from whole blood samples using an E.Z.N.A Blood DNA Kit (Omega Bio Tek). The DNA of the control subjects was isolated using the Chelex method from blood spots. DNA was ampli fied by multiplex PCR (Qiagen Multiplex MasterMix, Qiagen) using the GeneAmp PCR System 9700 (Applied Biosystems) under the fol lowing conditions: 95 C for 15 min, followed by 32 cycles at 94 C for 30 s, 57 C for 90 s, and 72 C for 90 s, then 72 C for 10 min and 4 C thereafter. The primers used in PCR are presented in Tab. 1. The PCR products were evaluated by agarose gel electrophoresis. Six µl of product was run in 2% agarose gel in 0.5 TBE buffer. The remaining PCR product was purified of incorporated primers and dntps by digestion with a mixture of Exol (0.1 µl, 20 U/µl) and SAP (1 µl, 1 U/µl) (Fermen tas) and a quantity of 0.5 µl was subjected to minisequencing. The minisequencing reaction (ABI Prism SNaPshot Multiplex Kit, Applied Bio systems) was performed as a multiplexing reaction using the GeneAmp PCR System 9700 (Applied Biosystems) under the following conditions: 25 cycles at 96 C for 10 s, 50 C for 5 s, and 60 C for 30 s, then 4 C thereafter. The primer set used in the minisequencing reaction is shown in Tab. 2. After 1 h of purification with SAP (0.5 µl, 1 U/µl), 1 µl SNaPshot products were separated with an ABI PRISM 3130 Genetic Analyzer in POP 4 polymer (Applied Biosystems) together with GeneScan 120 LIZ as the size standard. The data were analyzed using GeneScan Software v Two SNP polymorphisms (rs and
3 03-forszt.qxd 7/10/09 12:33 PM Page 217 The Genetic Basis of Prostate Cancer 217 Table 1. Sequences of primers used in the PCR multiplex reaction Tabela 1. Sekwencje primerów użytych w multipleksowej reakcji PCR Gene SNP Primers sequences Product size (bp) (Gen) (Sekwencje primerów) (Wielkość) VDR rs (F) 5 GTC TTG CAT GGG AAT AAC TTG (R) 5 GAT TGA ACC TAA GAT GTC ATT AC 3 VDR rs (F) 5 (GACT) 4 CCA CCA CTT GCC TAG CTG T 3 75 (R) 5 (GACT) 4 AGT GAC TTA CCC AGG GTC C 3 CDH1 rs16260 (F) 5 CAA AAG AAC TCA GCC AAG TGT A (R) 5 (GACT) 2 CGG CCT CGC ATA GAC GCG 3 Table 2. Sequences of primers used in the minisequencing reaction Tabela 2. Sekwencje primerów użytych w reakcji minisekwencjonowania Gene SNP Primers sequences Product size (bp) (Gen) (Sekwencje primerów) (Wielkość) VDR rs (F) 5 GTC TTG CAT GGG AAT AAC TTG 3 C 28, T 29 (R) 5 TTG CTG AGT GTG AAA TAA TTT TGC 3 G 29, A 27 VDR rs (F) 5 (GACT) 4 CCA CCA CTT GCC TAG CTG T3 C 39.5, G 38.5 (R) 5 (GACT) 4 AGT GAC TTA CCC AGG GTC C3 G 38.6, C 38.7 CDH1 rs16260 (F) 5 GTC TTG CAT GGG AAT AAC TTG 3 C 31.5, A 33 (R) 5 TTG CTG AGT GTG AAA TAA TTT TGC 3 G 30, T 32.6 rs ) in the VDR gene located on intron 4 and intron 1, respectively, and one (rs16260) in the CDH1 gene located in the promoter region were genotyped. Statistical Analysis The chi squared test was used to evaluate the Hardy Weinberg equilibrium (HWE) as well as the differences in genotype frequencies between the two groups. Non parametric tests (Wald Wolfowitz and Mann Whitney U) were used to assess correlation between genotype and PSA level and Gleason Score of the PC patients. Statistical significance was defined as p < The statistical analyses were performed with STA TISTICA 8 (StatSoft). The classical linkage dise quilibrium value (D) was computed for a two locus haplotype using the formula: D = hf p x q (hf haplotype frequency, p and q allele fre quency). Results Study Population Analysis No correlations were found between PSA level and GS (r = ), PC patient age and PSA level (r = ), or age and GS (r = ). Genotyping Analysis The main aim of this study was to assess dif ferences in the frequencies of SNPs in the VDR and CDH1 genes. The genotyped SNPs showed no divergence from Hardy Weinberg equilibrium (p = , p = , and p = for rs , rs , and rs16260, respectively). The rs SNP in VDR showed no statistical dif ference in genotype frequency (p = ); how ever, there was a slight increase in the C/C geno type in the PC patients, while in the control group the numbers of C/C homozygotes and C/T het erozygotes were equal. The rs SNP fre quency in VDR showed statistical difference (p = ), with the C/C genotype dominating in the control subjects and the number of G/C heterozy gotes considerably higher in the PC patients. The rs16260 SNP in CDH1 also showed a difference in genotype frequency between the two groups (p = ), with the A/C genotype occurring more frequently in the controls and the C/C homozy gotes prevalent in the PC patients. The genotype and allele frequencies are presented in Table 3. SNP Association Analysis The associations of particular genotypes with the clinical parameters of the PC patients were assessed using non parametric tests (Wald Wolfowitz and Mann Whitney U). No statistical
4 03-forszt.qxd 7/10/09 12:33 PM Page P. FORSZT et al. Table 3. Allelic and genotype distributions of the analyzed SNPs in the two groups Tabela 3. Rozkład częstości alleli i genotypów analizowanych SNP ów wśród badanych grup rs no. Location Allelic distribution (%) p Genotype distribution (%) p (Numer) (Umiejscowienie) (Rozkład częstości alleli) (Rozkład częstości genotypów) PC controls PC controls rs intron 4 C C/C T C/T T/T rs intron 1 G G/G C G/C C/C rs16260 promoter C C/C A C/A A/A correlations between the SNPs and the age at diag nosis were found. The C/C genotype of rs16260 in CDH1 gene positively correlated with the Gleason score (p = ); carriers of the C/C homozy gote were characterized by increased GS. Statistically significant association was also found for the C/C genotype of rs in VDR and increased PSA level (p = ). Rs in the VDR gene did not display statistical associa tion with PSA level or GS despite the fact this SNP showed a difference in frequency between the test ed groups. Linkage Disequilibrium: Two Locus Analysis In two locus analysis it was noted that the risk allele C/C of rs16260 was in linkage disequilibri um with the C/C genotype of rs (D = 0.728). Moreover, the number of C/C genotype in carriers of both SNPs was significantly greater in the PC patients than in the healthy controls (p = ). All PC patients with the C/C genotype of rs in VDR were carriers of the C/C geno type of rs16260 in CDH1. The Wald Wolfowitz (WW) and Mann Whitney U (MW) tests showed no significant association of the tested two locus haplotype with PSA level and GS (WW: p = and MW: p = for PSA and WW: p = and MW: p = for GS). Discussion The results presented here indicate that the genotyped single nucleotide polymorphisms in the VDR and CDH1 genes may increase the risk for PC, especially for G/G carriers of rs in the VDR and the C/C genotype of rs16260 in the CDH1 gene. Furthermore, the latter displayed associations with increased Gleason score. The rs SNP in VDR did not show significant differences in frequency; there was only a slight increase in the frequency of C/C carriers in the patient group. However, the carriers of this geno type were characterized by higher PSA levels. Moreover, two locus analysis showed linkage dis equilibrium between the C/C genotype of rs and the C/C genotype of rs16260 in the PC patients. The number of C/C C/C carriers of both SNPs was considerably higher in the patients than in the controls. VDR Gene Polymorphism SNPs in the VDR gene have been widely test ed by numerous research groups [7 10, 15]. In the present study, two SNPs located on intron 1 (rs ) and intron 4 (rs ) were ana lyzed. The results of rs obtained in this study are unique and contradict those of others. A study performed by Holick et al.  found sta tistically significant differences in genotype fre quency; however, the risk genotype was a rare homozygote. Unexpectedly, the present study showed that the G/G homozygote was the preva lent genotype in the PC patients and the rare allele occurred more frequently among the healthy sub jects. The results observed for rs also con tradict those obtained by Holick et al. In genotyp ing analysis, the present study found only a slight increase in homozygotes for the rare C/C genotype in the patient group as well as for the homozygote of the common G/G genotype, and the frequencies did not approach significance. Moon et al. obtained similar results, i.e. a lack of association between SNP rs and PC risk . Furthermore, the present study found statisti cally significant correlation between the C/C genotype of rs and increased PSA level. On the other hand, no correlation between Gleason
5 03-forszt.qxd 7/10/09 12:33 PM Page 219 The Genetic Basis of Prostate Cancer 219 score and the age at diagnosis was found. Holick et al.  and Moor et al.  also showed a lack of association between SNP variants of the VDR gene and clinical parameters; however, the correlation with PSA level found in the present study repre sents new data, not revealed by others. CDH1 Gene Polymorphism Since the CDH1 gene has been associated with increased risk of PC, numerous SNPs in this gene have been analyzed [16 19]. In the present study the genotype frequencies as well as the association between the progression of prostate cancer and an SNP located in the promoter region of CDH1 gene at the 160 locus upstream from the gene were analyzed. The results of this study contradict data obtained by other research groups. The at risk genotype in the Lower Silesian population was the C/C variant of 160A>C (rs16260). The C/A het erozygote dominated in healthy subjects, suggest ing a protective role rather than an association with an increased risk of PC. As the numbers of A/A carriers were equal in the two groups, there was no correlation with PC, which also varies from results obtained in previous studies [16 18] indicating that the A allele represented a risk allele for prostate cancer. Bonilla et al.  screened the whole promoter region and detected 21 SNPs, of which the 160 C/A variant (rs16260) showed higher association of the A allele with PC in European Americans. Jonsson et al.  obtained similar results, as did Lindström et al. , in which the A/A or heterozygous C/A variants cor related with increased risk of PC, which diametri cally differs from the results obtained in the pre sented Lower Silesian population. The association between the A allele of 160C/A (rs16260) poly morphism with increased risk of PC was con firmed in a meta analysis , especially in European and Asian populations. The present results decidedly demonstrate a protective role of the A/C genotype rather than correlation with increased risk. It should also be mentioned that the present study found an association between the C/C genotype and increased Gleason score, sug gesting an influence on the progression of prostate cancer. In conclusion, two of the three tested SNPs displayed statistically significant differences in frequency in patients with prostate cancer and in healthy controls. The results presented here diverge from those obtained by others, indicating disagreement about the association between these SNPs and prostate cancer. These differences might be due to the specific pattern of the Lower Silesian population or the coincidence of control and patient group selection. Further analyses must be performed to evaluate the role of the analyzed SNPs in the risk of prostate cancer. References  Jemal A, Siegel R, Ward E, Hao Y, Xu J, Murray T, Thun MJ: Cancer Statistic CA Cancer J Clin, 2008, 58,  Steinberg GD, Carter BS, Beaty TH, Childs B, Walsh PC: Family history and the risk of prostate cancer. Prostate 1990, 17,  Forrest MS, Edwards MS, Houlston R, Kote Jarai Z, Key T, Allen N, Knowles MA, Turner F, Ardern Jones A, Murkin A, Williams S, Oram R, Bishop DT, Eeles RA: Association between hormonal genetic polymor phisms and early onset prostate cancer. Prostate Cancer Prostatic Dis 2005, 8,  Schaid DJ: The complex genetic epidemiology of prostate cancer. Hum Mol Genet 2004, 13(1),  Gos M, Sadowska M, Wiechno P, Demkow T, Janik P: Tło genetyczne a ryzyko rozwoju raka prostaty oraz obraz kliniczny choroby. Urol Pol 2006, 59, Supl. 1.  Thorne J, Campbell MJ: The vitamin D receptor in cancer. Proc Mutr Soc 2008, 67(2),  Holick CN, Stanfork JL, Kwon EM, Ostrander EA, Nejentsev S, Ulrike P: Comprehensive association analy sis of the Vitamin D pathway genes, VDR, CYP27B1, and CYP24A1 in Prostate Cancer. Cancer Epidemiol Biomarkers Pre 2007, 16(10),  Moon S, Holle S, Bodiwala D, Luscombe CJ, French ME, Liu S, Saxby MF, Jones PW, Fryer AA, Strange R: Associations between G/A1229, A/G30875, C/T48200 and C/T65013 genotypes and haplotypes in the vitamin D receptor gene, ultraviolet radiation and susceptibility to prostate cancer. Ann Hum Gen 2006, 70,  Mikhak B, Humter DJ, Spiegelman D, Platz EA, Hollis BW, Giovannucci E: Vitamin D receptor (VDR) gene polymorphisms and haplotypes, interaction with plasma 25 hydroxvitamin D and 1,25 dihydroxyvitamin D and prostate cancer risk. Prostate 2007, 67(9),  Li H, Stampfer MJ, Hollis JB, Mucci LA, Gaziano JM. Hunter D, Giovannucci EL, Ma J: A prospective study of plasma vitamin D metabolites, vitamin D receptor polymorphisms and prostate cancer. Plos Med 2007, 3, e103.  Ingles SA, Ross RK, Yu MC, Irvine RA, LaPera G, Haile RW, Coetzee GA: Association of prostate cancer risk with genetic polymorphisms in Vitamin D Receptor and Androgen Receptor. J Nati Cancer Inst 1997, 89(2),
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