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Amplification of HSD17B1 and ERBB2 in primary breast cancer
Linköping University, Department of Biomedicine and Surgery, Oncology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Biomedicine and Surgery, Oncology. Linköping University, Faculty of Health Sciences.
Linköping University, Department of Biomedicine and Surgery, Surgery. Linköping University, Faculty of Health Sciences.
Department of Oncology, Huddinge University Hospital, Stockholm, Sweden.
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2003 (English)In: Oncogene, ISSN 0950-9232, E-ISSN 1476-5594, Vol. 22, no 1, 34-40 p.Article in journal (Refereed) Published
Abstract [en]

Estrogens play a crucial role in the development of breast cancer. Estradiol can be produced in the breast tissue in situ, and one of the enzymes involved in this process is 17β-hydroxysteriod dehydrogenase (17β-HSD) type 1 that catalyzes the interconversion of estrone (E1) to the biologically more potent estradiol (E2). The gene coding for 17β-HSD type 1 (HSD17B1) is located at 17q12-21, close to the more studied ERBB2 and BRCA1. The aim of this study was to investigate if HSD17B1 shows an altered gene copy number in breast cancer. We used real-time PCR and examined 221 postmenopausal breast tumors for amplification of HSD17B1 and ERBB2. In all, 32 tumors (14.5%) showed amplification of HSD17B1 and 21% were amplified for ERBB2. Amplification of the two genes was correlated (P = 0.00078) and in 14 tumors (44%) with amplification of HSD17B1, ERBB2 was co amplified. The patients with amplification in at least one of the genes had a significantly worse outcome than patients without (P = 0.0059). For estrogen receptor (ER)-positive patients who received adjuvant tamoxifen, amplification of HSD17B1 was related to decreased breast cancer survival (P = 0.017), whereas amplification of ERRB2 was not. Amplification of HSD17B1 might be an indicator of adverse prognosis among ER-positive patients, and possibly a mechanism for decreased benefit from tamoxifen treatment.

Place, publisher, year, edition, pages
2003. Vol. 22, no 1, 34-40 p.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-24842DOI: 10.1038/sj.onc.1206078PubMedID: 12527905Local ID: 9240OAI: oai:DiVA.org:liu-24842DiVA: diva2:245165
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Steroid converting enzymes in breast cancer
Open this publication in new window or tab >>Steroid converting enzymes in breast cancer
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Estrogens play a central role in the development of breast cancer. Most breast carcinomas are detected after menopause and despite a low degree of ovarian estrogen production and low levels of serum estrogen these tumors show a high in situ level of estrogens. Enzymes modulating local steroid availability seem to play an important role in the progression of especially estrogen receptor positive breast cancer. The 17ß-hydroxysteroid dehydrogenase (17ß-HSD) enzymes are involved in the interconversion of biologically active and inactive sex steroids and are considered to play a critical role in the in situ metabolism of estrogen.

The aim of this thesis was to investigate the expression of 17ß-HSD type 1 and 2 in breast cancer and correlate this to prognosis, and to analyze if the gene encoding 17ßHSD type 1 exhibits altered gene copy number in breast cancer. We also wanted to examine if the protein levels of aromatase, 17ßHSD type 1 and 17ßHSD type 2 show association with the expression of COX-2 in breast tumors and whether these proteins correlate to prognosis. Real-time RT-PCR was used to detect the rnRNA levels of 17ßHSD type 1 and type 2, and immunohistochemistry to detect the protein expression. To analyze if the gene encoding 17ßHSD type 1 exhibits altered gene copy number in breast cancer we used real-time PCR and genomic DNA.

While 17ßHSD type 1 catalyzes the conversion of estrone to the more potent estradiol, the type 2 enzyme catalyzes the opposite reaction. All tumors investigated in this study exhibited detectable rnRNA levels of 17ßHSD type 1. We found detectable rnRNA levels of 17ßHSD type 2 in the normal breast tissue, whereas many tumors lacked expression of type 2, especially among ER-positive tumors. In Paper I the expression of 17ßHSD type 2 was detectable in 14% of the tumors and in Paper III 17ßHSD type 2 mRNA was detected in 69% of the tumors. The expression of 17ßHSD type 2 seems to be lost in a subset of the breast tumors.

In Paper II we found amplification of the gene coding for 17ßHSD type 1 in 14.5% of the cases. HSD17B1 amplification had prognostic significance, and in particular, for ER-positive patients who received tamoxifen treatment, increased gene copy number indicated a decreased breast cancer survival. There was a significant correlation between HSD17B1 gene copy number and mRNA expression level of 17ßHSD type 1, when analyzing a subgroup of the patients.

In Paper II, among ER-positive patients, those with low expression of type 2 had a significantly higher recurrence rate compared with patients who expressed normal levels and this difference could not be seen among ER-negative patients. The prognostic significance of type 2 hold true in multivariate analysis. In Paper I, patients with late relapse in their disease more frequently had lost the mRNA expression of 17ßHSD type 2 than had matched control patients. In Paper IV, patients with ER-positive breast tumors with low protein levels of 17ßHSD type 2 had a worse prognosis, both concerning distant recurrence and breast cancer related death. In Paper I a high mRNA level of 17ßHSD type 1 predicted late relapses among breast cancer patients, however, in Paper IV a prognostic value of 17ßHSD type 1 could not be detected. In Paper III, there was no significant association between 17HSD type 1 and recurrence-free survival if the entire follow-up period was considered. However, for ER-positive patients still recurrence-free after 5 years, high levels of 17HSD type 1 was associated with a significantly higher rate of late relapse in the disease. When 17ßHSD type 1 and 2 were considered together, the expression ratio was a significant prognostic variable.

COX-2 protein expression was significantly correlated to aromatase, 17ßHSD type 1 and 17ßHSD type 2 levels, and this suggests that COX-2 might contribute to the upregulation of steroid converting enzymes. However, any significant prognostic value of COX-2 or aromatase could not be detected.

In summary, these results suggest that 17ß-HSD type 1 and 2 have prognostic importance in estrogen dependent breast cancer.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet, 2005. 76 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 908
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-31153 (URN)16890 (Local ID)91-85299-21-9 (ISBN)16890 (Archive number)16890 (OAI)
Public defence
2005-09-22, Berzeliussalen, Hälsouniversitetet, Linköping, 09:00 (Swedish)
Opponent
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2012-09-25Bibliographically approved

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Gunnarsson, CeciliaAhnström, MarieOlsson, BirgitNordenskjöld, BoStål, Olle

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