RESUMEN
In recent years, significant effort has been made to identify genes that influence breast cancer risk. Because the high-penetrance breast cancer susceptibility genes BRCA1 and 2 play a role only in a small fraction of breast cancer cases, understanding the genetic risk of the majority of breast cancers will require the identification and analysis of several lower penetrance genes. The estrogen-signaling pathway plays a crucial role in the pathophysiology of breast cancer; therefore, polymorphism in genes involved in this pathway is likely to influence breast cancer risk. Our detailed analysis of gene expression profiles of estrogen- and 4-OH-tamoxifen-treated ZR75-1 breast cancer cells identified members of the sulfotransferase 1A (SULT1A) phenol sulfotransferase family as downstream targets of tamoxifen. On the basis of the induction of SULT1A by 4-OH-tamoxifen and the known inherited variability in SULT1A enzymatic activity, we hypothesized that polymorphism in sulfotransferase genes might influence the risk of breast cancer. Using an RFLP that distinguishes an arginine to histidine change in exon 7 of the SULT1A1 gene, we characterized SULT1A1 genotypes in relation to breast cancer risk. An analysis of 444 breast cancer patients and 227 controls revealed no effect of SULT1A1 genotype on the risk of breast cancer (P = 0.69); however, it did appear to influence the age of onset among early-onset affected patients (P = 0.04). Moreover, individuals with the higher activity SULT1A1*1 allele were more likely to have other tumors in addition to breast cancer (P = 0.004; odds ratio, 3.02; 95% confidence interval, 1.32, 8.09). The large number of environmental mutagens and carcinogens activated by sulfotransferases and the high frequency of the SULT1A1*1 allele in human populations warrants additional studies to address the role of SULT genes in human cancer.
Asunto(s)
Arilsulfotransferasa/genética , Arilsulfotransferasa/metabolismo , Neoplasias de la Mama/enzimología , Neoplasias de la Mama/genética , Polimorfismo Genético , Adulto , Edad de Inicio , Alelos , Arginina/química , Northern Blotting , Estudios de Casos y Controles , Estrógenos/farmacología , Exones , Femenino , Genotipo , Histidina/química , Humanos , Immunoblotting , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Factores de Riesgo , Tamoxifeno/farmacología , Células Tumorales CultivadasRESUMEN
We observed an artifactual reactivity on Western blots when heparin was used as the anticoagulant in collected blood specimens. This nonspecific interaction was found to be due to immunoglobulin aggregates that bound to cellular proteins, in particular histones. Nonspecific interaction was not observed in fresh heparinized samples, but was present in samples frozen for long-term storage. Other anticoagulants such as EDTA, oxaloacetate and sodium citrate did not cause this nonspecific reactivity. Although adding heparin to serum could reproduce the nonspecific reactivity on Western blots, other immunological tests such as ELISA or indirect immunofluorescence were not affected by the use of heparinized plasma. Enzymatic digestion of heparinized samples with Heparinase I removed the artifactual reactivity, leaving specific antigen-antibody interactions unaffected. Therefore, we advise caution in the interpretation of Western blotting experiments when blood or other tissue fluid specimens are collected in heparin.