Search

The human epidermal growth factor receptor (HER) 4 is a relative of HER2 and has been associated to endocrine breast cancer and prediction of tamoxifen response. In addition to PI3K/Akt and MAPK pathway activation, ligand binding to HER4 triggers proteolytic cleavage and release of an intracellular receptor domain (4ICD) with signaling properties. The aim of the present study was to analyze HER4 protein expression and intracellular localization in breast cancer tissue from patients randomized to treatment with or without adjuvant tamoxifen. To investigate HER4 expression and localization in response to estradiol (E2) and 4-hydroxytamoxifen (4-OHT) exposure, we also performed in vitro studies. Cytoplasmic, nuclear and membrane expression of HER4 protein was evaluated by immunohistochemical staining in tumor tissue from 912 breast cancer patients. Three different breast epithelia cancer cell lines were exposed to E2 and 4-OHT and mRNA expression was analyzed using qPCR. Further, nuclear and cytoplasmic proteins were separated and analyzed with western blotting. We found an association between nuclear HER4 protein expression and ER-positivity (P=0.004). Furthermore, significant association was found between cytoplasmic HER4 and ER-negativity (P<0.0005), PgR-negativity (P<0.0005), tumor size >20 mm (P=0.001) and HER2-negativity (P=0.008). However, no overall significance of HER4 on recurrence-free survival was found. After E2 exposure, HER4 mRNA and protein expression had decreased in two cell lines in vitro yet no changes in nuclear or cytoplasmic protein fractions were seen. In conclusion, nuclear HER4 seem to be co-located with ER, however, we did not find support for overall HER4 expression in independently predicting response of tamoxifen treatment. The possible influence of separate isoforms was not tested and future studies may further evaluate HER4 significance., Funding Agencies:Nyckelfonden, Örebro University Hospital, SwedenLions Cancer Research Foundation, Region Uppsala - Örebro, SwedenStockholm Cancer Society, Sweden

In order to obtain a comprehensive DNA methylation signature of HER2-positive breast cancer (HER2+ breast cancer), we performed a genome-wide methylation analysis on 17 HER2+ breast cancer and compared with ten normal breast tissue samples using the Illumina Infinium HumanMethylation450 BeadChip (450K). In HER2+ breast cancer, we found altered DNA methylation in genes involved in multicellular development, differentiation and transcription. Within these genes, we observed an overrepresentation of homeobox family genes, including several genes that have not been previously reported in relation to cancer (DBX1, NKX2-6, SIX6). Other affected genes included several belonging to the PI3K and Wnt signaling pathways. Notably, HER2, AKT3, HK1, and PFKP, genes for which altered methylation has not been previously reported, were also identified in this analysis. In total, we report 69 candidate biomarker genes with maximum differential methylation in HER2+ breast cancer. External validation of gene expression in a selected group of these genes (n = 13) revealed lowered mean gene expression in HER2+ breast cancer. We analyzed DNA methylation in six top candidate genes (AKR1B1, INA, FOXC2, NEUROD1, CDKL2, IRF4) using EpiTect Methyl II Custom PCR Array and confirmed the 450K array findings. Future clinical studies focusing on these genes, as well as on homeobox-containing genes and HER2, AKT3, HK1, and PFKP, are warranted which could provide further insights into the biology of HER2+ breast cancer.

The International Tamoxifen Pharmacogenomics Consortium was established to address the controversy regarding cytochrome P450 2D6 (CYP2D6) status and clinical outcomes in tamoxifen therapy. We performed a meta-analysis on data from 4,973 tamoxifen-treated patients (12 globally distributed sites). Using strict eligibility requirements (postmenopausal women with estrogen receptor-positive breast cancer, receiving 20 mg/day tamoxifen for 5 years, criterion 1), CYP2D6 poor metabolizer status was associated with poorer invasive disease-free survival (IDFS: hazard ratio = 1.25; 95% confidence interval = 1.06, 1.47; P = 0.009). However, CYP2D6 status was not statistically significant when tamoxifen duration, menopausal status, and annual follow-up were not specified (criterion 2, n = 2,443; P = 0.25) or when no exclusions were applied (criterion 3, n = 4,935; P = 0.38). Although CYP2D6 is a strong predictor of IDFS using strict inclusion criteria, because the results are not robust to inclusion criteria (these were not defined a priori), prospective studies are necessary to fully establish the value of CYP2D6 genotyping in tamoxifen therapy., Funding Agencies:National Institutes of Health (National Institute of General Medical Sciences)National Institutes of Health (National Cancer Institute)National Institutes of Health (National Institute of Child Health and Human Development)Breast Cancer Research (Scotland) Tayside Tissue Bank California Breast Cancer Research Program Cancer Research UK Deutsches Krebsforschungszentrum, Heidelberg, Germany Robert Bosch Foundation, Stuttgart, Germany Marie Curie Initial Training Network "FightingDrugFailure" GrantStichting Emmanuel van der Schueren (scientific partner of the Vlaamse Liga tegen Kanker) National Project for Personalized Genomic Medicine, Ministry for Health & Welfare, Republic of Korea Deutsche Forschungsgemeinschaft, Germany

Reduced or absent Wwox expression has recently been associated with tamoxifen resistance in breast cancer and has also been proposed as a candidate predictive marker for treatment. We aimed to investigate the correlation of Wwox expression with the outcome of tamoxifen treatment by examining tissues from 912 randomized breast cancer patients. Paraffin-embedded tissues from patient tumors were arranged on tissue microarray, and Wwox protein was stained using immunohistochemistry. After microscopic examination, the results were analyzed with Cox regression, Kaplan-Meier survival curves and the log-rank test. In the group of cases having a tumor absent for Wwox expression, there was no difference in recurrence-free survival between treated and untreated patients (P=0.81). For treated cases with a tumor expressing moderate or strong Wwox protein, recurrence-free survival was improved (P=0.001 and P=0.003, respectively). The test for interaction between Wwox and treatment response demonstrated a decreased risk of recurrence for treated patients with a moderate or strong Wwox expression (HR=0.31, 95% CI 0.10-0.98 and HR=0.28, 95% CI 0.08-0.97, respectively). Our results indicate that patients with high expression of Wwox may gain more benefit from treatment with tamoxifen.

Solute carrier family 25A member 43 (SLC25A43) gene is a putative tumor suppressor gene that undergoes loss of heterozygosity (LOH) in human epidermal growth factor receptor 2 (HER2) positive breast cancer. Also, knockdown of SLC25A43 in cell lines influences cell turnover and metabolism. Absence of mutations in this gene in breast cancers prompted us to study methylation as an alternate mechanism for gene inactivation of this X encoded gene. Quantification of CpG site methylation using pyrosequencing was performed upstream of the SLC25A43 gene and at its 5' end in a cohort of breast tumor tissues (n = 80, HER2 positive or negative) with different SLC25A43 gene deletion status. Compared with control tissue, cancer tissues had lower levels of methylation at the 5' and 3' shores of the gene. Cancer tissues with no deletion in the SLC25A43 gene (Del (-)) had higher methylation in the CpG island (CGI) of the gene than cancers carrying the deletion (Del (+)). Methylation in the CGI of the SLC25A43 gene was negatively correlated with age at diagnosis. In HER2 positive breast cancer, ER negativity and lymph node positivity was associated with higher methylation in the CGI and in the adjacent shores of this gene. Our results suggest that methylation in the CGI of the SLC25A43 gene could be an alternate mechanism of gene silencing in the absence of LOH. Also, associations between site-specific methylation and clinicopathological parameters suggest that epigenetic changes in SLC25A43 gene could be of importance in breast carcinogenesis.

Background: Overexpression of the human epidermal growth factor receptor (HER) 2 is associated with poor prognosis and shortened survival in breast cancer patients. HER2 is a potent activator of several signaling pathways that support cell survival, proliferation and metabolism. In HER2- positive breast cancer there are most likely unexplored proteins that act directly or indirectly downstream of well established pathways and take part in tumor development and treatment response. Methods: In order to identify novel copy number variations (CNVs) in HER2-positive breast cancer whole-genome single nucleotide polymorphism (SNP) arrays were used. A PCR-based loss of heterozygosis (LOH) assay was conducted to verify presence of deletion in HER2-positive breast cancer cases but also in HER2 negative breast cancers, cervical cancers and lung cancers. Screening for mutations was performed using single-strand conformation polymorphism (SSCP) followed by PCR sequencing. Protein expression was evaluated with immunohistochemistry (IHC). Results: A common deletion at chromosome Xq24 was found in 80% of the cases. This locus harbors the gene solute carrier (SLC) family 25A member 43 (SLC25A43) encoding for a mitochondrial transport protein. The LOH assay revealed presence of SLC25A43 deletion in HER2-positive (48%), HER2-negative (9%), cervical (42%) and lung (67%) cancers. HER2- positive tumors with negative or low SLC25A43 protein expression had significantly lower S-phase fraction compared to tumors with medium or high expression (P = 0.024). Conclusions: We have found deletion in the SLC25A43 gene to be a common event in HER2-positive breast cancer as well as in other cancers. In addition, the SLC25A43 protein expression was shown to be related to S-phase fraction in HER2-positive breast cancer. Our results indicate a possible role of SLC25A43 in HER2-positive breast cancer and support the hypothesis of altered mitochondrial function in cancer., CC BY 2.0This study was supported by grants from Swedish Cancer Society, Nyckelfonden Örebro Sweden and Lion Cancer Foundation Sweden.

The anticancer drug tamoxifen (TAM) displays two chiral vinyl propeller structures, which interconvert so rapidly that the process is undetectable on the NMR time scale. In the present work, the enantiomerization processes were investigated with molecular modeling techniques. The threshold mechanisms probed at the different rings were shown to be identical, i.e., involving a synchronous three-ring flip, with a correlated rotation of the rings. In order to reveal the pharmacological profiles of the two chiral forms, we performed structural studies on the ligand binding domain of estrogen receptor alpha. (ER alpha LBD) and associated ligands. The enantiomers, with opposite torsional twist, were found to be discriminated by ER alpha. For TAM and its main metabolites, the effects of the stereoselectivity of ER alpha are overcome by the low energy cost for helical inversion between the two torsional enantiomers, estimated to be similar to 3 kcal/mol., QC 20121126

We provide a detailed description of the cis-trans isomerization of 4-hydroxytamoxifen/endoxifen catalyzed by several isoforms from the cytochrome P450 (CYP) superfamily, including CYP1B1, CYP2B6, and CYP2C19. We show that the reactions mainly involve redox processes catalyzed by CYP, DFT calculation results strongly suggest that the isomerization occurs via a cationic intermediate. The cationic cis-isomer is more than 3 kcal/mol more stable than the trans form, resulting in an easier conversion from trans-to-cis than cis-to-trans. The cis-trans isomerization is a rarely reported CYP reaction and is ascribed to the lack of a second abstractable proton on the ethenyl group of the triarylvinyl class of substrates. The cationic intermediates thus formed instead of the stable dehydrogenation products allow for isomerization to occur. As a comparison, the reactions for the tamoxifen derivatives are compared to those of other substrates, 4-hydroxyacetanilide and raloxifene, for which the stable dehydrogenation products are formed., QC 20121126

Hypermethylation of the O6-MGMT, p14ARF, p16INK4a, RASSF1A and APC1A genes are unfavourable prognostic markers in colorectal cancer (CRC). We hypothesized that they could be related to prognosis also in cervical cancer. Methylation was studied in DNA extracts from surgical specimens of cancer tissue by novel pyrosequencing methods. In 109 patients (90 squamous cell carcinomas, 19 adenocarcinomas), we found that hypermethylation of the APC1A gene promoter occurred in 8.3% of patients, and of p16INK4a in 1.8%. APC1A hypermethylation was significantly related to more advanced FIGO stage of the tumor (P=0.013), larger tumor diameter (P=0.049) and distant recurrence-free survival (P=0.0007), but not with locoregional recurrence rate, age, HPV status, DNA ploidy, tumor grade or malignancy grading score. We conclude that methylation of the APC1A promoter in cervical cancer, as diagnosed by pyrosequencing, is significantly related to major biological characteristics of the tumor, and may be a new predictor of poor prognosis in cervical cancer.

Aromatase is an important enzyme in the local synthesis of oestrogens and its expression has been shown to be increased in breast cancer through the activation of multiple promoters. However, the mechanisms behind this are not yet fully understood. A novel candidate in this context is the transcription factor forkhead box L2 (FOXL2), which has been recognised to be co-expressed with aromatase and transcriptionally active promoter 11 in developing goat and chicken ovaries. We propose that FOXL2 could be involved in the increased expression of aromatase in breast cancer. We examined FOXL2 and its relation to aromatase in 132 postmenopausal breast cancer patients by immunohistochemistry. Using in silico analysis, we further searched for FOXL2 binding-elements in the aromatase gene promoters. The results demonstrate that FOXL2 is expressed in breast cancer and influences clinical outcome with improved recurrence-free survival in cases with nuclear expression. In a multivariate Cox model, nuclear FOXL2 was a significant prognostic factor in ER-positive patients treated with tamoxifen (HR=0.18, 95% confidence interval (CI)=0.04-0.81, P=0.03). Tumours expressing nuclear FOXL2 were also more likely positive for stromal and/or cytoplasmic aromatase (P=0.03 and P=0.008, respectively). In silico analyses revealed binding elements of FOXL2 in promoters 1.3, 11 and 17 of the aromatase gene of which promoter 1.7 was most significant. In conclusion, this is the first study to report that FOXL2 is expressed in breast cancer and correlates with aromatase as well as with clinical outcome. The results further strengthen a possible binding of FOXL2 to aromatase promoter 1.7. Nevertheless, whether FOXL2 is a direct activator of aromatase requires further investigation.

Staphylococcus epidermidis is a significant pathogen in neonatal sepsis and other nosocomial infections. For further investigations of the colonisation patterns and invasive pathways, typing methods that are applicable on large populations of bacterial isolates are warranted. In the present study, a genotyping method based on polymerase chain reaction (PCR) for the repeat regions of four genes (sdrG, sdrF, aap and sesE) that encode for bacterial surface proteins was developed and applied to a sample of well-characterised neonatal blood isolates of S. epidermidis (n = 49). The PCR products were visualised on agarose gel (sdrG, sdrF and sesE) or by fragment analysis (aap). The discriminatory index (D-index) for genotyping of the different genes was compared to genotyping by pulsed-field gel electrophoresis (PFGE). The highest D-index for the PCR-based typing methods was found for the combination of sdrF, sdrG and aap (D-index 0.94), whereas the optimal two-gene combination (sdrF and aap) resulted in a D-index of 0.92. We conclude that the described method can be used for the genotyping of large populations of S. epidermidis isolates with a sufficient discriminatory capacity, and we suggest that the combination of sdrF and aap is the most suitable to use.

The p53 protein and its regulator MDM2 is central to tumorigenesis by directing cells to undergo cell cycle arrest and/or apoptosis in response to DNA damage or other stress signals. The genes encoding these proteins contain nucleotide variation (p53 codon 72, MDM2 SNP309) that influences cellular response. We examined the p53 codon 72 and MDM2 SNP309 to determine their implication with age of disease onset and risk of breast cancer in young women (andlt;= 36 years). No risk of breast cancer was observed for the genotypes of p53 and MDM2, however, a tendency (P=0.15) towards increased risk of early onset breast cancer was observed in carriers of two or more Pro and/or G alleles. We further calculated the influence on age at diagnosis. Cases were grouped according to the number of G and Pro alleles (0, 1, 2 or 3-4) and age at diagnosis. A significant trend towards decreased age at diagnosis with increased number of risk alleles was found (P=0.013). Our results suggest that p53 codon 72 and MDM2 SNP309 may be implicated in early onset breast cancer.

The p53 tumor suppressor gene has a central role in the defense against cancer, including breast cancer, and contains a polymorphic variant (Arg/Pro) at codon 72 that has been shown to have different biological properties regarding apoptosis and cell cycle arrest. Earlier studies have shown allele specific loss of heterozygosity (LOH) at this particular site and we aimed to investigate its biological relevance in codon 72 heterozygous breast cancer patients (i.e., survival and age of disease onset). 199 postmenopausal cases were analyzed for LOH using MegaBACE1000 and statistics was performed using Statistical Package for Social Sciences. LOH was found in totally 124 (62.3%) patients and the Pro allele (n = 103) was significantly more often deleted compared to the Arg allele (n = 21) (P = 0.001). Patients with LOH of the Arg allele were diagnosed at an earlier age (mean age 62.5 years) than those with loss of the Pro allele (mean age 69.2 years) (P = 0.011). LOH of the Arg allele was also associated with worse survival (P = 0.05). LOH in comparison to ROH correlated significantly with increased S-phase fraction. Tumor size, stage or number of positive lymph nodes was not related to LOH. Our results and earlier findings suggest a selective loss of the Pro allele during carcinogenesis that might confer a growth advantage for cancer cells. On the other hand, it appears to be more harmful for patients to loose the Arg allele since we found that loss of this allele was associated with earlier onset and worse prognosis.

Background: Adjuvant therapy of breast cancer patients reduces the risk of recurrence and mortality, although, a substantial proportion of patients acquire resistance and relapse in the disease. Predictors of therapeutic response are therefore important to avoid both therapy resistance and the side effects of inefficient regimes. The p53 protein is a key determinant to induce either growth arrest or apoptosis in response to cytotoxic stress. Methods: In the search for predictive markers of cancer therapy we investigated a common Arg72/Pro72 polymorphism in the p53 gene, which has been shown to influence the apoptotic potential. Using PCR and RFLP we genotyped 220 breast cancer patients randomized to radiotherapy versus chemotherapy and tamoxifen versus no tamoxifen. Results: Oestrogen-receptor positive patients possessing at least one Pro72 allele had better distant recurrence-free survival when randomized to tamoxifen compared to those who were not (P=0.0033), as also demonstrated by the significantly decreased hazard ratio (HR=0.28, 95% CI 0.12–0.65). Among patients homozygous for the Arg72 genotype the outcome was approximately equal between tamoxifen treated and non-tamoxifen treated patients (P=0.65). When the calculated hazard ratios for the genotypes were compared by an interaction test a significant difference was found (P=0.0088). Conclusion: The present report indicates that the codon 72 polymorphism in the p53 gene may be a predictor of tamoxifen response, suggesting that breast cancer patients lacking the Pro72 allele might be candidates for other therapies.

Background Tamoxifen is widely used as endocrine therapy for oestrogen-receptor-positive breast cancer. However, many of these patients experience recurrence despite tamoxifen therapy by incompletely understood mechanisms. In the present report we propose that tamoxifen resistance may be due to differences in activity of metabolic enzymes as a result of genetic polymorphism. Cytochrome P450 2D6 (CYP2D6) and sulfotransferase 1A1 (SULT1A1) are polymorphic and are involved in the metabolism of tamoxifen. The CYP2D6*4 and SULT1A1*2 genotypes result in decreased enzyme activity. We therefore investigated the genotypes of CYP2D6 and SULT1A1 in 226 breast cancer patients participating in a trial of adjuvant tamoxifen treatment in order to validate the benefit from the therapy. Methods The patients were genotyped using PCR followed by cleavage with restriction enzymes. Results Carriers of the CYP2D6*4 allele demonstrated a decreased risk of recurrence when treated with tamoxifen (relative risk = 0.28, 95% confidence interval = 0.11–0.74, P = 0.0089). A similar pattern was seen among the SULT1A1*1 homozygotes (relative risk = 0.48, 95% confidence interval = 0.21–1.12, P = 0.074). The combination of CYP2D6*4 and/or SULT1A1*1/*1 genotypes comprised 60% of the patients and showed a 62% decreased risk of distant recurrence with tamoxifen (relative risk = 0.38, 95% confidence interval = 0.19–0.74, P = 0.0041). Conclusion The present study suggests that genotype of metabolic enzymes might be useful as a guide for adjuvant endocrine treatment of postmenopausal breast cancer patients. However, results are in contradiction to prior hypotheses and the present sample size is relatively small. Findings therefore need to be confirmed in a larger cohort., Original Publication: Pia Wegman, Linda Vainikka, Olle Stål, Bo Nordenskjöld, Lambert Skoog, Lars-Erik Rutqvist and Sten Wingren, Genotype of metabolic enzymes and the benefit of tamoxifen in postmenopausal breast cancer patients, 2005, Breast Cancer Research, (7), R284-290. http://dx.doi.org/10.1186/bcr993 Licensed by: CURRENT SCIENCE LTD

The detoxification enzyme sulfotransferase1A1 (SULT1A1) is implicated in the inactivation of estrogens and the activation of promutagens andprocarcinogens. SULT1A1 activity varies among individuals, and this difference in phenotype is, in part, controlled by genetic polymorphism (Arg→His in codon 213). It is hypothesized that the His allele contributes to the risk of postmenopausal breast cancer. Frequencies of the Arg/His alleles were estimated in 229 postmenopausal breast cancer patients and 227 age-matched controls using a PCR-RFLP assay. Allele frequencies and genotype distributions were not statistically different between postmenopausal breast cancer patients and the population-based controls, i.e. neither of the alleles is associated with an increased risk of breast cancer in the present study.

The aim of this study was to assess the incidence and prognosis in early onset breast cancer. Age-adjusted incidence and death rate for the 5394 Swedish women diagnosed with breast cancer under the age of 40 between 1960 and 1996 was studied using data from the Swedish Cancer Registry and Swedish Death Cause Registry. A total of 107 consecutive young patients with invasive breast cancer undergoing surgery during 1980–1993 in the Southeast Swedish health care region were retrospectively followed up and their cancers reviewed and graded blindly. The median follow-up time was 11.2 years. The applicability of the Nottingham Prognostic Index (NPI) as a prognostic tool was investigated. Grade, age, node status, tumour size, S-phase fraction and steroid receptor content were related to survival univariately and multivariately in a Cox proportional hazard analysis. The incidence of early onset breast cancer has increased moderately and the survival rate has not improved during the last 35 years. When young women are diagnosed with breast cancer their tumours are larger, their lymph nodes more often involved, and the median grade higher than in older with 64% having grade 3 tumours. Lymph node status was the strongest sole prognostic indicator but the use of NPI gave more accurate prognostic information than node status alone.

Oestrogen exposure has long been considered to be a main risk factor of breast cancer. More recently, interest has also focused on the possible carcinogenic influence from oestrogen metabolites, such as catechol oestrogens. O-methylation, catalysed by Catechol-O-Methyltransferase (COMT), is one pathway by which the potentially carcinogenic catechol oestrogens can be inactivated. The gene coding for COMT protein contains a single-nucleotide polymorphism (SNP), resulting in an amino acid shift Val Met, which has been shown to determine high- and low-activity configuration of the enzyme. We hypothesized that the low-activity allele, COMTMet, may be implicated in early onset breast cancer. In the present case–control study, including 126 young breast cancer patients ( 36 years) and 117 healthy female blood donors, we analysed the association between COMTMet genotype and risk of breast cancer. No significant difference in the frequency of low-/high-activity alleles was found between cases and controls, indicating that the polymorphism, as a single factor, may not contribute to breast carcinogenesis in young women.

The aim of this study was to investigate the frequency of p53 alterations in bilateral breast cancer and to evaluate a possible clonal relationship between the paired tumours regarding p53 alteration and other pathobiological variables. Tumours from 34 patients were investigated with immunohistochemistry, single strand conformation polymorphism analysis and DNA-sequence analysis applied to exons 5-8. Fifteen percent of the 68 tumours showed positive immunoreaction and/or presence of mutation. The occurrence of p53 accumulation was 9% and the prevalence of gene mutation 10%. No significant concordance was found between the tumours in the same patient for p53 alterations, progesterone receptor status or DNA ploidy. S-phase fraction showed a weak correlation, not statistically significant. Oestrogen receptor status was the only variable that exhibited a significant concordance. No convincing evidence was found for other associations between the paired tumours or for a high prevalence of p53 alterations in bilateral breast cancer.

Frequent allelic deletions at chromosome 11q24-q25 have been described in both early and late onset breast cancers, suggesting the existence of a gene locus implicated in the initiation and/or progression of the disease. In the present study we fine mapped this region further by loss of heterozygosity (LOH) analysis in a population of early onset breast cancer cases (n = 102, 22 to 36 years old). Loss of chromosomal material was assessed for possible association with patient survival as well as Nottingham histologic grade (NHG). Additionally, we investigated the involvement of the 11q24-q25 locus in a group of familial breast cancer cases with no detectable BRCA1 or BRCA2 gene alterations (n = 32, ages 28 to 40 years). Among the consecutive patients, extensive LOH was observed for all markers at 11q24-q25, with frequencies ranging from 42% to 54%. Deletion at the D11S4125 marker was found to be associated with reduced survival (p = 0.026), whereas the adjacent D11S387 marker correlated with higher histologic grade (p = 0.042). In the familial cases, the most telomeric markers showed substantially lower proportions of LOH, ranging from 10% to 21%. Comparison of the two patient groups demonstrated that this difference in LOH frequency was statistically significant for the D11S4098, D11S968, D11S387 and D11S4125 markers (p = 0.020, p = 0.029, p = 0.0070 and p = 0.0030, respectively). We conclude that 11q25 may harbor a gene implicated in early onset breast cancer. Our data suggest that the most probable position for this locus is defined by the markers D11S387 and D11S4125 and furthermore that it may play a less significant role in familial breast cancer cases not linked to either of the BRCA genes.

The vitamin D3 receptor gene (VDR) contains a TaqI RFLP that is associated with increased VDR mRNA stability, increased serum levels of 1α,25-dihydroxyvitamin D3 (1,25-D3), and decreased risk for prostate cancer. Determination of the TaqI genotype, in a group of young women with breast cancer (n = 111; age, <37 years) and a control population (n = 130), revealed no overall association to risk for breast cancer. However, patients without TaqI site (TT genotype) showed a significantly increased risk for lymph node metastasis (relative risk, 1.8, 95% confidence interval, 1.3- 2.6). Furthermore, a tendency toward an increased survival was found among estrogen receptor-positive, tamoxifen-treated patients who were homozygous for the TaqI site (P = 0.075). We conclude that polymorphism in the VDR gene may influence tumor progression and tamoxifen treatment response in early- onset breast carcinomas.

Long-term exposure to oestrogens is a well-recognised risk factor for breast cancer, whereas little is known about the influence of polymorphisms of genes involved in oestrogen biosynthesis and metabolism. A candidate, containing a single bp polymorphism, T→C, (designated, A2 allele), might be the CYP17 gene, which codes for an enzyme involved in oestrogen synthesis. This polymorphism creates an additional Sp1-type promoter site (CCACC box), which has been shown to be associated with increased serum oestrogen levels. We performed a case-control study, to evaluate association of the CYP17 gene polymorphism with risk of breast cancer in young women (younger than 37 years). We found a statistically significant increased risk in carriers of at least 1 A2 allele [odds ratio (OR), 2.0; 95% confidence interval (CI), 1.1–3.5, p = 0.027], and a trend toward a gene-dose effect illustrated by a slightly higher risk for A2-homozygous subjects (OR, 2.8) than for heterozygous women (OR, 1.9). Furthermore, when we investigated the CYP17 genotype in relation to tumour characteristics, breast cancer patients with 1 or 2 A2 alleles tended to have lower oestrogen receptor levels (risk ratio, 0.70; CI, 0.41–1.2, p = 0.44). Our findings suggest that CYP17 gene polymorphism influences breast carcinogenesis in young women.