RESUMEN

Trastuzumab has markedly improved the treatment and long-term prognosis of patients with HER2-positive breast cancer. A frequent clinical challenge in patients with relapsing and/or metastatic disease is de novo or acquired trastuzumab resistance, and to date no predictive biomarkers for palliative trastuzumab have been established. In the present study, the prognostic values of factors involved in the HER2-associated PI3K/Akt signalling pathway were explored. The first 46 consecutive patients treated at the Department of Oncology, Linköping University Hospital between 2000 and 2007 with trastuzumab for HER2-positive metastatic breast cancer were retrospectively included. The gene copy number variation and protein expression of several components of the PI3K/Akt pathway were assessed in the tumour tissue and biopsy samples using droplet digital polymerase chain reaction and immunohistochemistry. Patients with tumours displaying a high-grade ERBB2 (HER2) amplification level of ≥6 copies had a significantly improved overall survival hazard ratio [(HR)=0.4; 95%, confidence interval (CI): 0.2-0.9] and progression-free survival (HR=0.3; 95% CI: 0.1-0.7) compared with patients with tumours harbouring fewer ERBB2 copies. High-grade ERBB2 amplification was significantly associated with the development of central nervous system metastases during palliative treatment. Copy gain (≥3 copies) of the gene encoding the tyrosine phosphatase PTPN2 was associated with a shorter overall survival (HR=2.0; 95% CI: 1.0-4.0) and shorter progression-free survival (HR=2.1; 95% CI: 1.0-4.1). In conclusion, high ERBB2 amplification level is a potential positive prognostic factor in trastuzumab-treated HER2-positive metastatic breast cancer, whereas PTPN2 gain is a potential negative prognostic factor. Further studies are warranted on the role of PTPN2 in HER2 signalling.

RESUMEN

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.

Asunto(s)

Neoplasias de la Mama/patología , Receptor ErbB-4/biosíntesis , Moduladores Selectivos de los Receptores de Estrógeno/uso terapéutico , Tamoxifeno/uso terapéutico , Biomarcadores de Tumor/análisis , Western Blotting , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/mortalidad , Femenino , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , Modelos de Riesgos Proporcionales , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptor ErbB-2/biosíntesis , Receptores de Estrógenos/biosíntesis , Análisis de Matrices Tisulares

RESUMEN

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.

Asunto(s)

Neoplasias de la Mama/genética , Metilación de ADN , Genoma Humano , Receptor ErbB-2/genética , Biomarcadores de Tumor/genética , Biomarcadores de Tumor/metabolismo , Neoplasias de la Mama/metabolismo , Islas de CpG , Epigénesis Genética , Femenino , Genes Homeobox , Humanos , Fosfatidilinositol 3-Quinasas/genética , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Receptor ErbB-2/metabolismo , Vía de Señalización Wnt

RESUMEN

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.

Asunto(s)

Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Oxidorreductasas/genética , Tamoxifeno/administración & dosificación , Proteínas Supresoras de Tumor/genética , Antineoplásicos Hormonales/administración & dosificación , Neoplasias de la Mama/patología , Quimioterapia Adyuvante , Supervivencia sin Enfermedad , Resistencia a Antineoplásicos/efectos de los fármacos , Femenino , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Estimación de Kaplan-Meier , Oxidorreductasas/metabolismo , Pronóstico , Proteínas Supresoras de Tumor/metabolismo , Oxidorreductasa que Contiene Dominios WW

RESUMEN

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.

Asunto(s)

Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Eliminación de Gen , Receptor ErbB-2/metabolismo , Proteínas Supresoras de Tumor/genética , Adulto , Anciano , Proliferación Celular , Deleción Cromosómica , Cromosomas Humanos X , Variaciones en el Número de Copia de ADN , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Pérdida de Heterocigocidad , Persona de Mediana Edad , Proteínas Supresoras de Tumor/metabolismo

RESUMEN

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.

Asunto(s)

Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Metilación de ADN , Epigénesis Genética , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo , Estudios de Casos y Controles , Islas de CpG/genética , Femenino , Eliminación de Gen , Regulación Neoplásica de la Expresión Génica , Silenciador del Gen , Humanos , Leucocitos/metabolismo , Pérdida de Heterocigocidad , Masculino

RESUMEN

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.

Asunto(s)

Sistema Enzimático del Citocromo P-450/metabolismo , Antagonistas de Estrógenos/química , Tamoxifeno/análogos & derivados , Biocatálisis , Isomerismo , Oxidación-Reducción , Tamoxifeno/química

RESUMEN

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.

Asunto(s)

Proteínas Adaptadoras Transductoras de Señales/genética , Inhibidor p16 de la Quinasa Dependiente de Ciclina/genética , Metilación de ADN , Neoplasias del Cuello Uterino/genética , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Metilasas de Modificación del ADN/genética , Metilasas de Modificación del ADN/metabolismo , Enzimas Reparadoras del ADN/genética , Enzimas Reparadoras del ADN/metabolismo , Supervivencia sin Enfermedad , Epigenómica , Femenino , Humanos , Pronóstico , Regiones Promotoras Genéticas , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo , Neoplasias del Cuello Uterino/metabolismo , Neoplasias del Cuello Uterino/patología

RESUMEN

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 α (ERα LBD) and associated ligands. The enantiomers, with opposite torsional twist, were found to be discriminated by ERα. For TAM and its main metabolites, the effects of the stereoselectivity of ERα are overcome by the low energy cost for helical inversion between the two torsional enantiomers, estimated to be ∼3 kcal/mol.

Asunto(s)

Antineoplásicos/química , Antineoplásicos/metabolismo , Receptor alfa de Estrógeno/metabolismo , Tamoxifeno/química , Tamoxifeno/metabolismo , Receptor alfa de Estrógeno/química , Simulación de Dinámica Molecular , Unión Proteica , Conformación Proteica , Teoría Cuántica , Estereoisomerismo , Especificidad por Sustrato , Tamoxifeno/análogos & derivados , Termodinámica

RESUMEN

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 II 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 post-menopausal 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 I.3, II and I.7 of the aromatase gene of which promoter I.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 I.7. Nevertheless, whether FOXL2 is a direct activator of aromatase requires further investigation.

Asunto(s)

Antineoplásicos Hormonales/uso terapéutico , Biomarcadores de Tumor/metabolismo , Neoplasias de la Mama/tratamiento farmacológico , Factores de Transcripción Forkhead/metabolismo , Tamoxifeno/uso terapéutico , Aromatasa/metabolismo , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Citocromo P-450 CYP1A1/metabolismo , Femenino , Proteína Forkhead Box L2 , Humanos , Estimación de Kaplan-Meier , Pronóstico , Regiones Promotoras Genéticas , Carga Tumoral

RESUMEN

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 (

Asunto(s)

Neoplasias de la Mama/genética , Codón , Genes p53 , Polimorfismo de Nucleótido Simple , Proteínas Proto-Oncogénicas c-mdm2/genética , Adulto , Femenino , Genes BRCA1 , Genes BRCA2 , Humanos , Mutación

RESUMEN

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 MegaBACE(1000) 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.

Asunto(s)

Alelos , Neoplasias de la Mama/genética , Carcinoma/genética , Estrógenos , Genes p53 , Neoplasias Hormono-Dependientes/genética , Polimorfismo de Nucleótido Simple , Edad de Inicio , Anciano , Anciano de 80 o más Años , Neoplasias de la Mama/epidemiología , Neoplasias de la Mama/patología , Carcinoma/epidemiología , Carcinoma/patología , Codón/genética , Femenino , Humanos , Estimación de Kaplan-Meier , Pérdida de Heterocigocidad , Metástasis Linfática , Persona de Mediana Edad , Proteínas de Neoplasias/análisis , Neoplasias Hormono-Dependientes/epidemiología , Neoplasias Hormono-Dependientes/patología , Posmenopausia , Pronóstico , Receptores de Estrógenos/análisis , Fase S , Suecia/epidemiología

RESUMEN

BACKGROUND: The two-gene expression ratio HOXB13:IL17BR has been proposed to predict the outcome of tamoxifen-treated breast cancer patients. We intended to examine whether this ratio can predict the benefit of 5 years vs. 2 years of tamoxifen treatment of postmenopausal patients. A further objective was to investigate any prognostic effects of the ratio in systematically untreated premenopausal patients. Based on the current knowledge of HOXB13 and IL17BR, we hypothesized that these genes may have individual prognostic or predictive power. PATIENTS AND METHODS: Expression of HOXB13 and IL17BR were quantified by real-time PCR in tumors from 264 randomized postmenopausal patients and 93 systemically untreated premenopausal patients. RESULTS: A high HOXB13:IL17BR ratio was associated with aggressive tumor characteristics, as were low levels of IL17BR alone. The ratio and HOXB13 alone predicted recurrence-free survival after endocrine treatment, with a benefit of prolonged treatment in estrogen receptor-positive patients correlated to a low ratio (recurrence rate ratio: RR = 0.39; P = 0.030), or low expression of HOXB13 (RR = 0.37; P = 0.015). No difference in recurrence-free survival was seen for the high ratio or high HOXB13 subgroups. The predictive value of HOXB13 and HOXB13:IL17BR was significant in multivariate analysis. In the systemically untreated cohort, only IL17BR showed independent prognostic significance. CONCLUSION: We conclude that the ratio or HOXB13 alone can predict the benefit of endocrine therapy, with a high ratio or a high expression rendering patients less likely to respond. We have also shown that IL17BR might be an independent prognostic factor in breast cancer.

Asunto(s)

Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Proteínas de Homeodominio/genética , Receptores de Interleucina/genética , Estudios de Cohortes , Supervivencia sin Enfermedad , Femenino , Regulación Neoplásica de la Expresión Génica , Proteínas de Homeodominio/metabolismo , Humanos , Posmenopausia , Premenopausia , Receptores de Estrógenos/metabolismo , Receptores de Interleucina/metabolismo , Receptores de Interleucina-17 , Recurrencia , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Tamoxifeno/farmacología , Resultado del Tratamiento

RESUMEN

BACKGROUND: The risk of developing breast cancer is strongly correlated with the overall exposure to oestrogen and most tumours are more or less dependent on oestrogen for their growth. A great majority of breast cancers occur after menopause when the ovaries have ceased to be functional, yet breast tumours in postmenopausal women maintain high intratumoural oestrogen concentrations, primarily through enzymatic conversion of androgenic precursors. PATIENTS: with a hormone dependent tumour generally receive the anti-oestrogen tamoxifen that mediate its anti-tumour effect by competing with oestrogen for binding to the oestrogen-receptor (ER). We therefore propose that the levels of oestrogen producing enzymes may affect the prognosis in postmenopausal breast cancer patients treated with tamoxifen. METHODS: We measured the mRNA and protein levels of aromatase and sulfatase by real-time PCR (n=161) and immunohistochemistry (n=131) in postmenopausal women with breast cancer. RESULTS: A significant better recurrence-free survival was detected in patients with weak or high protein expression of stromal aromatase (P=0.0008), as also demonstrated by a decreased relative risk (RR=0.50, CI=0.33-0.76, P=0.003). When we combined patients with weak and high stromal aromatase and selected only ER-positive patients, the improved prognosis was even more evident (P=0.0000) and was shown to be a significant prognostic factor in a multivariate Cox-model (HR=0.15, CI=0.06-0.39, P=0.000). The mRNA expression of aromatase and sulfatase, as well as the protein expression of sulfatase revealed no prognostic significance. CONCLUSION: Protein expression of stromal aromatase may serve as a significant prognostic marker in ER-positive patients.

Asunto(s)

Aromatasa/genética , Neoplasias de la Mama/enzimología , Neoplasias de la Mama/genética , Estrógenos/metabolismo , Posmenopausia , Sulfatasas/genética , Aromatasa/metabolismo , Neoplasias de la Mama/patología , Femenino , Humanos , Técnicas para Inmunoenzimas , Recurrencia Local de Neoplasia/enzimología , Recurrencia Local de Neoplasia/genética , Recurrencia Local de Neoplasia/patología , Pronóstico , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Neoplásico/genética , ARN Neoplásico/metabolismo , Receptores de Estrógenos/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Células del Estroma/enzimología , Células del Estroma/patología , Sulfatasas/metabolismo , Tasa de Supervivencia , Análisis de Matrices Tisulares

RESUMEN

INTRODUCTION: Tamoxifen therapy reduces the risk of recurrence and prolongs the survival of oestrogen-receptor-positive patients with breast cancer. Even if most patients benefit from tamoxifen, many breast tumours either fail to respond or become resistant. Because tamoxifen is extensively metabolised by polymorphic enzymes, one proposed mechanism underlying the resistance is altered metabolism. In the present study we investigated the prognostic and/or predictive value of functional polymorphisms in cytochrome P450 3A5 CYP3A5 (*3), CYP2D6 (*4), sulphotransferase 1A1 (SULT1A1; *2) and UDP-glucuronosyltransferase 2B15 (UGT2B15; *2) in tamoxifen-treated patients with breast cancer. METHODS: In all, 677 tamoxifen-treated postmenopausal patients with breast cancer, of whom 238 were randomised to either 2 or 5 years of tamoxifen, were genotyped by using PCR with restriction fragment length polymorphism or PCR with denaturing high-performance liquid chromatography. RESULTS: The prognostic evaluation performed in the total population revealed a significantly better disease-free survival in patients homozygous for CYP2D6*4. For CYP3A5, SULT1A1 and UGT2B15 no prognostic significance was observed. In the randomised group we found that for CYP3A5, homozygous carriers of the *3 allele tended to have an increased risk of recurrence when treated for 2 years with tamoxifen, although this was not statistically significant (hazard ratio (HR) = 2.84, 95% confidence interval (CI) = 0.68 to 11.99, P = 0.15). In the group randomised to 5 years' tamoxifen the survival pattern shifted towards a significantly improved recurrence-free survival (RFS) among CYP3A5*3-homozygous patients (HR = 0.20, 95% CI = 0.07 to 0.55, P = 0.002). No reliable differences could be seen between treatment duration and the genotypes of CYP2D6, SULT1A1 or UGT2B15. The significantly improved RFS with prolonged tamoxifen treatment in CYP3A5*3 homozygotes was also seen in a multivariate Cox model (HR = 0.13, CI = 0.02 to 0.86, P = 0.03), whereas no differences could be seen for CYP2D6, SULT1A1 and UGT2B15. CONCLUSION: The metabolism of tamoxifen is complex and the mechanisms responsible for the resistance are unlikely to be explained by a single polymorphism; instead it is a combination of several mechanisms. However, the present data suggest that genetic variation in CYP3A5 may predict response to tamoxifen therapy.

Asunto(s)

Antineoplásicos Hormonales/farmacología , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Sistema Enzimático del Citocromo P-450/genética , Tamoxifeno/metabolismo , Tamoxifeno/farmacología , Anciano , Anciano de 80 o más Años , Arilsulfotransferasa/genética , Arilsulfotransferasa/metabolismo , Citocromo P-450 CYP2D6/genética , Citocromo P-450 CYP2D6/metabolismo , Citocromo P-450 CYP3A , Sistema Enzimático del Citocromo P-450/metabolismo , Supervivencia sin Enfermedad , Femenino , Glucuronosiltransferasa/genética , Glucuronosiltransferasa/metabolismo , Humanos , Persona de Mediana Edad , Polimorfismo Genético , Posmenopausia , Resultado del Tratamiento

RESUMEN

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.

Asunto(s)

Neoplasias de la Mama/terapia , Codón , Genes p53 , Variación Genética , Polimorfismo Genético , Alelos , Antineoplásicos Hormonales/administración & dosificación , Quimioterapia Adyuvante , Femenino , Humanos , Radioterapia Adyuvante , Tamoxifeno/administración & dosificación , Resultado del Tratamiento

Asunto(s)

Antineoplásicos Hormonales/uso terapéutico , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Citocromo P-450 CYP2D6/genética , Tamoxifeno/uso terapéutico , Neoplasias de la Mama/enzimología , Femenino , Humanos , Selección de Paciente , Pronóstico , Reproducibilidad de los Resultados

RESUMEN

The detoxification enzyme sulfotransferase1A1 (SULT1A1) is implicated in the inactivation of estrogens and the activation of promutagens and procarcinogens. 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.

Asunto(s)

Arilsulfotransferasa/genética , Neoplasias de la Mama/enzimología , Neoplasias de la Mama/genética , Posmenopausia/genética , Anciano , Alelos , Arilsulfotransferasa/metabolismo , Femenino , Predisposición Genética a la Enfermedad , Genotipo , Humanos , Persona de Mediana Edad , Polimorfismo Genético , Posmenopausia/metabolismo

RESUMEN

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.

Asunto(s)

Antineoplásicos Hormonales/farmacología , Arilsulfotransferasa/genética , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Citocromo P-450 CYP2D6/genética , Tamoxifeno/farmacología , Adulto , Anciano , Antineoplásicos Hormonales/uso terapéutico , Arilsulfotransferasa/metabolismo , Quimioterapia Adyuvante , Citocromo P-450 CYP2D6/metabolismo , Femenino , Genotipo , Humanos , Persona de Mediana Edad , Metástasis de la Neoplasia , Reacción en Cadena de la Polimerasa , Polimorfismo Genético , Posmenopausia , Recurrencia , Factores de Riesgo , Tamaño de la Muestra , Tamoxifeno/uso terapéutico , Resultado del Tratamiento

RESUMEN

PURPOSE: Manganese superoxide dismutase (MnSOD) is one of the major enzymes implicated in the cellular defence against reactive oxygen species. Low expression of MnSOD has been observed in different cancer tissues and several reports have shown that overexpression of MnSOD inhibits growth in various human cancer cells. These observations suggest that MnSOD is involved in carcinogenesis. A polymorphism (Ala-9Val) in the mitochondrial targeting sequence (MTS) of the MnSOD gene has been proposed to affect protein localization and thereby influence cellular defence against superoxide radicals. METHODS: In the present case-control study, including 118 early onset breast cancer patients (

Asunto(s)

Neoplasias de la Mama/enzimología , Neoplasias de la Mama/etiología , Predisposición Genética a la Enfermedad , Polimorfismo Genético , Superóxido Dismutasa/genética , Adulto , Alelos , Estudios de Casos y Controles , Femenino , Genotipo , Humanos , Estrés Oxidativo/genética , Factores de Riesgo