| 1. |
- Ahnström, Marie, et al.
(författare)
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Altered expression of cyclin E and the retinoblastoma protein influences the effect of adjuvant therapy in breast cancer
- 2009
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Ingår i: International Journal of Oncology. - : Spandidos Publications. - 1019-6439 .- 1791-2423. ; 34:2, s. 441-448
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Tidskriftsartikel (refereegranskat)abstract
- Cyclin E and the retinoblastoma protein (Rb) are both important regulators of the G(1) phase in the cell cycle. Overexpression of cyclin E and lost expression of Rb has previously been observed in breast tumours at frequencies of 10-50% and 20-30%, respectively. We explored the prognostic role of cyclin E and Rb in breast cancer patients randomised for tamoxifen (TAM), CMF (cyclophosphamide, metotrexate, 5-fluorouracil) chemotherapy and radiotherapy (RT) and how their expression affects the patients response to treatment. Protein expression was assessed with immunohistochemistry. We found overexpression of cyclin E in 32.1% (71/221) of the tumours and loss of Rb expression in 25.0% (59/236). Increased expression of cyclin E correlated to dysfunctional p53 (P=0.003) while loss of Rb correlated to normal p53 status (P=0.001). Our results suggest that patients with high cyclin E tumours have less benefit from tamoxifen (ER+, TAM vs. no TAM; RR=0.97; 95% CI, 0.36-2.60) than patients whose tumours show low expression (ER+, TAM vs. no TAM; RR =0.41; 95% CI, 0.24-0.72). Cyclin E also tended to predict the benefit from radiotherapy with a local recurrence rate of 0.31 (RT vs. CMF; 95% CI, 0.12-0.93) for patients with low expression and 0.68 (RT vs. CMF; 95% CI, 0.2-2.32) for patients with high expression of cyclin E. When the p53 status was taken in consideration the results showed that patients with both normal p53 and normal Rb expression had considerably lower locoregional recurrence rate when treated with radiotherapy instead of CMF (RR=0.17; 95% CI, 0.052-0.58) as compared to patients with either altered Rb or p53 or both (RR=0.70; 95% CI, 0.28-1.73).
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| 2. |
- Osorio, A., et al.
(författare)
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Evaluation of a candidate breast cancer associated SNP in ERCC4 as a risk modifier in BRCA1 and BRCA2 mutation carriers. Results from the consortium of investigators of modifiers of BRCA1/BRCA2 (CIMBA)
- 2009
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Ingår i: British Journal of Cancer. - : Nature Publishing Group. - 0007-0920 .- 1532-1827. ; 101:12, s. 2048-2054
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Tidskriftsartikel (refereegranskat)abstract
- Background: In this study we aimed to evaluate the role of a SNP in intron 1 of the ERCC4 gene (rs744154), previously reported to be associated with a reduced risk of breast cancer in the general population, as a breast cancer risk modifier in BRCA1 and BRCA2 mutation carriers. Methods: We have genotyped rs744154 in 9408 BRCA1 and 5632 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) and assessed its association with breast cancer risk using a retrospective weighted cohort approach. Results: We found no evidence of association with breast cancer risk for BRCA1 (per-allele HR: 0.98, 95% CI: 0.93-1.04, P0.5) or BRCA2 (per-allele HR: 0.97, 95% CI: 0.89-1.06, P0.5) mutation carriers. Conclusion: This SNP is not a significant modifier of breast cancer risk for mutation carriers, though weak associations cannot be ruled out.
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| 3. |
- Jansson, Agneta, 1973-, et al.
(författare)
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A new polymorphism in the coding region of exon four in HSD17B2 in relation to risk of sporadic and hereditary breast cancer
- 2007
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Ingår i: Breast Cancer Research and Treatment. - : Springer Science and Business Media LLC. - 0167-6806 .- 1573-7217. ; 106:1, s. 57-64
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Tidskriftsartikel (refereegranskat)abstract
- In situ synthesis of oestrogens is of great importance in the development and progression of breast cancer. 17β-hydroxysteroid dehydrogenase (17HSD) type 2 catalyses oxidation from oestradiol to oestrone, and thereby protects the breast epithelial cells from oestradiol. Low expression of 17HSD type 2 has been associated with decreased survival in breast cancer, but no studies have investigated the mechanism behind the low expression. The 17HSD type 2 gene (HSD17B2) was screened for mutations with Single Stranded Conformation Polymorphism (SSCP)-DNA sequencing in 59 sporadic breast cancer cases, 19 hereditary breast cancer cases and seven breast cancer cell lines. DNA samples from 226 healthy individuals were used to identify if changes were previously unknown polymorphisms. No mutation was detected and therefore mutations in HSD17B2 do not explain why some breast tumours exhibit low 17HSD type 2 expression. However, a previously unknown polymorphism was found in exon four (Met226Val). Using molecular modelling, we found that the substituted residue is located at the outer part of the steroid binding site, probably causing minor alterations in the substrate binding. We further studied if the polymorphism contributes to breast cancer susceptibility in a larger material, but did not find an increased risk in the group of 317 sporadic breast cancer patients, 188 breast cancer patients with two close relatives with breast cancer or 122 hereditary breast cancer patients, compared to the healthy control group. We suggest that the detected polymorphism does not contribute to a higher risk of developing breast cancer.
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| 4. |
- Söderlund, Karin, 1979-, et al.
(författare)
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The BRCA1/BRCA2/Rad51 complex is a prognostic and predictive factor in early breast cancer
- 2007
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 84:3, s. 242-251
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Tidskriftsartikel (refereegranskat)abstract
- Background and Purpose: The breast cancer susceptibility genes BRCA1 and BRCA2 interact with Rad51, one of the central components in the homologous recombination repair pathway. This study evaluates the prognostic and predictive role of BRCA1, BRCA2 and Rad51, individually and as a complex, in breast cancer.Material and Methods: Expression of BRCA1, BRCA2 and Rad51 was investigated using immunohistochemistry in tumours from 224 women with early breast cancer, who were randomised to receive postoperative radiotherapy or adjuvant chemotherapy (CMF).Results: 53% (112/212) of the tumours had reduced expression of the BRCA1/BRCA2/Rad51 complex. Low expression correlated to high histologic grade (p=0.05). Patients with low expression of the complex developed significantly more local recurrences as compared to patients with high expression (RR=3.20, 95% C.I. 1.48-6.88, p=0.003). Expression of the BRCA1/BRCA2/Rad51 complex was an independent prognostic factor in multivariate analysis (p=0.03). Patients with low expression of the complex responded well to radiotherapy (RR=0.31, 95% C.I. 0.14-0.70, p=0.005), whereas patients with high expression had few local recurrences and no additional benefit from radiotherapy (RR=1.08, 95% C.I. 0.40-2.90, p=0.88).Conclusions: Low expression of the BRCA1/BRCA2/Rad51 complex is a marker of poor prognosis, but predicts good effect of radiotherapy in patients with early breast cancer.
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| 5. |
- Söderlund Leifler, Karin, 1979-
(författare)
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DNA repair pathways and the effect of radiotherapy in breast cancer
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A large proportion of breast cancer patients are treated with radiotherapy. Ionising radiation induces different DNA damages, of which double-strand breaks are the most severe. They are mainly repaired by homologous recombination or non-homologous end-joining. Different protein complexes have central roles in these repair processes. In addition to the ability to repair DNA damage, cellular radiosensitivity is also affected by mitogenic signals that stimulate survival and inhibit apoptosis. The phosphatidylinositol 3-kinase (PI3-K)/AKT pathway controls cell proliferation, invasiveness and cell survival. AKT is regulated by upstream growth factor receptors, one of them being HER2 (also called ErbB2). HER2 is overexpressed in 15-30% of all breast cancers and associated with poor prognosis.In this thesis, we have studied factors that affect tumour cell resistance to ionising radiation. In Paper I, the role of HER2/PI3-K/AKT signalling in radiation resistance was investigated in two breast cancer cell lines. The results support the hypothesis that the HER2/PI3-K/AKT pathway is involved in resistance to radiation-induced apoptosis in breast cancer cells in which this signalling pathway is overstimulated.We also investigated if the protein expression of several DNA repair-associated proteins influence the prognosis and treatment response in early breast cancer. Moderate/strong expression of the MRE11/RAD50/NBS1 (MRN) complex predicted good response to radiotherapy, whereas patients with negative/weak MRN had no benefit from radiotherapy as compared to chemotherapy (Paper II). These results suggest that an intact MRNcomplex is important for the tumour-eradicating effect of radiotherapy. In Paper III, low expression of the BRCA1/BRCA2/RAD51 complex was associated with an aggressive phenotype, an increased risk of local recurrence and good response to radiotherapy.In Paper IV, we studied if a single nucleotide polymorphism, RAD51 135G/C, was related to RAD51 protein expression, prognosis and therapy resistance. We found that genotype was not correlated to neither protein expression nor prognosis. Patients who were G/G homozygotes had a significant benefit from radiotherapy. The results also suggested that the RAD51 135G/C polymorphism predicts the effect of chemotherapy in early breast cancer.In conclusion, DNA repair proteins are potential prognostic and predictive markers. The results indicate that proteins in different repair pathways may contribute differently to the effect of radiotherapy. Also, the HER2/PI3-K/AKT signalling pathway protects cells from radiation-induced apoptosis. In the future, it might be possible to target some of these proteins with inhibitory drugs to sensitise tumours to radiotherapy.
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| 6. |
- Söderlund Leifler, Karin, 1979-, et al.
(författare)
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Intact Mre11/Rad50/Nbs1 complex predicts good response to radiotherapy in early breast cancer
- 2007
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - : Elsevier BV. - 0360-3016 .- 1879-355X. ; 68:1, s. 50-58
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Post-operative radiotherapy is offered to a majority of breast cancer patients, since it significantly reduces the risk of local recurrence. However, some patients still develop recurrences. Owing to their vital roles in the repair of radiation-induced double-strand breaks, the Mre11/Rad50/Nbs1 (MRN) complex and the ATM protein might be implicated in tumour cell resistance to radiotherapy. The aim of this study was to investigate the expression and predictive role of these DNA repair proteins for the outcome of radiotherapy in breast cancer patients.Patients and Methods: The protein expression of ATM and the proteins in the MRN complex were investigated using immunohistochemistry in tumours from 224 women with early breast cancer, who were randomised to receive post-operative radiotherapy or adjuvant chemotherapy (CMF).Results: Compared to normal breast tissue, the staining intensity of Mre11, Rad50, Nbs1 and ATM was reduced in a majority of the tumours. Weak expression of the MRN complex was correlated to high histological grade and ER negativity (p=0.01 and p=0.0001). Radiotherapy significantly reduced the risk of local recurrence as compared to chemotherapy (p=0.04). The greatest benefit of radiotherapy was seen in patients with moderate/strong expression of the MRN complex (RR=0.27, 95% C.I. 0.098-0.72, p=0.009), whereas patients with negative/weak MRN had no benefit of radiotherapy compared to CMF. These results suggest that an intact MRN complex is important for the tumour cell eradicating effect of radiotherapy.
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| 7. |
- Wegman (Palmebäck), Pia, et al.
(författare)
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p53 polymorphic variants at codon 72 and the outcome of therapy in randomized breast cancer patients
- 2006
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Ingår i: Pharmacogenetics and Genomics. - : Ovid Technologies (Wolters Kluwer Health). - 1744-6872. ; 16:5, s. 347-351
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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