Journal Article

Sex hormone-binding globulin polymorphisms in familial and sporadic breast cancer

Asta Försti, Qianren Jin, Ewa Grzybowska, Magnus Söderberg, Helena Zientek, Marzena Sieminska, Jadwiga Rogozinska-Szczepka, Ewa Chmielik, Beata Utracka-Hutka and Kari Hemminki

in Carcinogenesis

Volume 23, issue 8, pages 1315-1320
Published in print August 2002 | ISSN: 0143-3334
Published online August 2002 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/23.8.1315
Sex hormone-binding globulin polymorphisms in familial and sporadic breast cancer

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Ovarian steroids are one of the strongest risk factors for breast cancer. Sex hormone-binding globulin (SHBG) binds and transports sex steroids in the blood, regulating their bioavailable fraction and access to target cells. It can also inhibit the estradiol-induced proliferation of breast cancer cells through its membrane receptor. Three coding-region polymorphisms, which lead to an amino acid change, have been reported. We studied the influence of these three polymorphisms on breast cancer risk in three different populations: Polish familial breast cancer cases, 27% of them carrying a BRCA1/BRCA2 mutation, Nordic familial and sporadic breast cancer cases. The reported G to A polymorphism in exon 1 was not found in the 423 analyzed samples. Instead, we found a C to T transition causing an arg to cys amino acid change within the same codon in one Polish breast cancer patient and her daughter. Both of them were heterozygotes for the exon 8 G to A polymorphism as well. They were diagnosed for bilateral breast cancer and carried a BRCA1 mutation (5382insC). Analysis of the tumor samples showed that they had lost the wild-type allele both at exons 1 and 8 of the SHBG gene. Analysis of the other Polish samples showed no correlation of the exon 8 polymorphism to breast cancer, bilateral breast cancer, BRCA1/BRCA2 mutations or age at diagnosis. No association of the exon 8 polymorphism with breast cancer in the Nordic familial or sporadic cases was found. The C to T polymorphism located in exon 4 was rare in all the studied populations (overall allele frequency 0.011). However, in each of the study populations there was a trend for a lower variant allele frequency in cancer cases than in controls. Variant allele frequency in all the breast cancer cases was significantly lower than in all the controls (χ2 = 5.27, P-value 0.02; odds ratio = 0.23, 95% confidence interval 0.05–0.84).

Keywords: CI, confidence interval; OR, odds ratio; RFLP, restriction fragment length polymorphism; SHBG, sex hormone-binding globulin

Journal Article.  4372 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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