Assoziationen zwischen Polymorphismen im Topoisomerase II alpha Gen mit der Länge des HER2-Amplikons auf Chromosom 17 - Implikationen für Mechanismen der Genamplifikation und die Prognose bei Mammakarzinompatientinnen

Background and hypothesis: The amplification status of the gene Topoisomerase IIα (TOP2A) is a known predictive factor in breast cancer patients, who are treated with anthracycline chemotherapy. TOP2A is located on Chromosome 17q21. Topoisomerase IIα plays a key role in DNA replication and repairing. Furthermore it is the molecular target of anthracycline chemotherapies. Several studies could associate TOP2A gene amplification or deletion with an altered response to anthracycline chemotherapy. It is never amplified without a coamplification of the HER2 gene, which is located on the same chromosome. However in most of the cases HER2 is amplified without TOP2A. Aim of this study was therefore to examine whether genetic polymorphisms in the TOP2A gene are prognostic factors in breast cancer patients and whether the genotype is correlated with the TOP2A amplification status of the tumor. Methods: The Bavarian Breast Cancer Cases and Controls study (BBCC) is a prospective cohort study, which aims at researching breast cancer risk and prognostic factors. Biomaterials such as germline DNA and tumor tissue is available from most of the patients. Real-time-PCR was performed in order to genotype the single nucleotide polymorphism (SNP) rs13695 in the 3’UTR region of the TOP2A gene. Amplification of the TOP2A gene was quantified by fluorescent in situ hybridization (FISH) of the same patients. The tumours were available as a tissue microarray (TMA), which was constructed from paraffin embedded tumours. Genotyping results were analyzed concerning their prognostic relevance in this breast cancer patient cohort and genotype and amplification status were associated with each other. Results: The genotype of the SNP rs13695 could be ascertained of 1.276 patients. A homozygous genotype CC could be seen in 736 patients (57,7 %), the heterozygous CT genotype and the homozygous alternative genotype TT was present in 459 (36 %) and 81 (6 %) patients respectively. In the multivariate survival analysis the genotype of rs13695 was statistically only significant in patients who received an adjuvant chemotherapy with an adjusted hazards ratio per allele of 1,69 (95 % confidence interval CI: 1,14 to 2,51; p = 0,009). In patients who did not receive a chemotherapy the genotype had no prognostic relevance at all. FISH results for gene copy number variation analysis were available of 629 patients. 587 (93,3 %) patients had a normal gene copy number of TOP2A, 33 patients (5,2 %) and 9 patients (1,4 %) showed an amplification or a deletion. Associating the rs13695 genotype with the amplification status of TOP2A, an increasing proportion of tumors with an amplification was seen with each T allele. Patients with a CC genotype had an amplification of the TOP2A in the tumor in 3,9 % of all cases and in 6,8 % and 9,7 % for the CT and the TT genotype respectively (p = 0,042). Conclusion: The genotype of the SNP rs13695 seems to be of independent prognostic relevance in breast cancer patients, who are treated with a chemotherapy. Furthermore the genotype was correlated with the gene amplification status in the tumor. The reason for this observation remains unclear. Further evaluation of the SNP as prognostic factor and the association with the amplification status are to be subject to further investigation.Hintergrund und Hypothese: Eine Chemotherapie mit Anthrazyklinen stellt zurzeit die Standardtherapie bei der Therapie von Patientinnen mit Mammakarzinom dar. Der Amplifikationsstatus des Gens Topoisomerase IIα (TOP2A) ist ein prädiktiver Faktor für die Wirksamkeit einer Anthrazyklin-Chemotherapie. Dies wird damit in Zusammenhang gebracht, dass TOP2A eines der Angriffsziele dieser Chemotherapie ist. Auf Chromosom 17q21 ist TOP2A Bestandteil eines langen Amplikons, welches vom zentromerisch gelegenen HER2-Gen bis zu TOP2A reicht. TOP2A wird nie ohne HER2 amplifiziert, allerdings ist HER2 in den meisten Fällen ohne TOP2A amplifiziert. Die molekularen Gründe hierfür sind unbekannt. Ziel dieser Arbeit ist es, den Einfluss genetischer Polymorphismen im TOP2A-Gen auf die Prognose von Mammakarzinompatientinnen und den TOP2A-Amplifikationsstatus zu untersuchen. Methoden: Die Bavarian Breast Cancer Cases and Controls Studie (BBCC) ist eine prospektive Kohortenstudie zur Untersuchung von Risiko- und Prognosefaktoren bei Mammakarzinompatientinnen. Von den meisten Patientinnen sind Biomaterialien wie Keimbahn-DNA und Tumorgewebe verfügbar. An Keimbahn-DNA wurde der Single Nucleotide Polymorphism (SNP) rs13695 in der 3´UTR-Region von TOP2A mittels quantitativer Real-Time-PCR genotypisiert. Zur Bestimmung des Amplifikationsstatus des TOP2A-Gens wurde ein Tissue Microarray aus in Formalin fixiertem, in Paraffin eingebettetem Tumormaterial hergestellt und mittels fluoreszierender in situ Hybridisierung die Genkopienzahl von HER2 und TOP2A quantifiziert. Diese molekularen Marker wurden untereinander und mit der Prognose des Mammakarzinoms assoziiert. Ergebnisse: Insgesamt 1.276 Patientinnen konnten für den SNP rs13695 genotypisiert werden. Der homozygote CC-Genotyp war bei 736 Patientinnen (57,7 %) vorhanden, der heterozygote CT- und der homozygote TT-Genotyp konnte in 459 (36 %) bzw. in 81 (6 %) Patientinnen gefunden werden. Für Patientinnen, die eine Chemotherapie erhalten hatten, konnte in der multivariaten Überlebensanalyse gezeigt werden, dass der Genotyp ein unabhängiger prognostischer Faktor war. Die adjustierte Hazards Ratio (HR) pro T-Allel betrug 1,69 (95 % Konfidenzintervall: 1,14 bis 2,51; p = 0,009). Für Patientinnen, die keine Chemotherapie erhalten hatten, war der Genotyp nicht von prognostischer Relevanz. Die Bestimmung der Genkopienzahl von TOP2A im Tumor war in 629 Fällen durchführbar. 587 Patientinnen (93,3 %) hatten eine normale Genkopienzahl, 33 Patientinnen zeigten eine Amplifikation (5,2 %) und bei 9 Patientinnen war TOP2A im Tumor deletiert (1,4 %). Bei der Untersuchung der Assoziation zwischen dem Genotyp rs13695 und dem Amplifikationsstatus von TOP2A konnte gesehen werden, dass der Anteil der amplifizierten Patientinnen mit dem T-Allel zunimmt. Bei Patientinnen mit dem homozygoten CC-Genotyp zeigte sich in nur 3,9 % der Fälle eine Amplifikation, während diese bei heterozygotem CT- und homozygotem TT-Genotyp in 6,8 % bzw. 9,7% der Tumoren gesehen werden konnte (p = 0,042). Schlussfolgerung: Der TOP2A Genotyp in Bezug auf den SNP rs13695 scheint bei Mammakarzinompatientinnen, die eine Chemotherapie erhalten, eine unabhängige prognostische Bedeutung zu haben. Des Weiteren scheint der Genotyp mit dem Amplifikationsstatus dieses Gens assoziiert zu sein. Die kausale Beziehung zwischen dem Keimbahngenotyp, dem Amplifikationsstatus und der Prognose ist noch unklar und sollte Bestandteil weiterer Untersuchungen sein

Associations between polymorphisms of the topoisomerase II alpha gene and the length of the HER2-amplicon on chromosome 17 - implications for mechanisms of geneamplification and the prognosis of breast cancer patients

Hintergrund und Hypothese: Eine Chemotherapie mit Anthrazyklinen stellt zurzeit die Standardtherapie bei der Therapie von Patientinnen mit Mammakarzinom dar. Der Amplifikationsstatus des Gens Topoisomerase IIα (TOP2A) ist ein prädiktiver Faktor für die Wirksamkeit einer Anthrazyklin-Chemotherapie. Dies wird damit in Zusammenhang gebracht, dass TOP2A eines der Angriffsziele dieser Chemotherapie ist. Auf Chromosom 17q21 ist TOP2A Bestandteil eines langen Amplikons, welches vom zentromerisch gelegenen HER2-Gen bis zu TOP2A reicht. TOP2A wird nie ohne HER2 amplifiziert, allerdings ist HER2 in den meisten Fällen ohne TOP2A amplifiziert. Die molekularen Gründe hierfür sind unbekannt. Ziel dieser Arbeit ist es, den Einfluss genetischer Polymorphismen im TOP2A-Gen auf die Prognose von Mammakarzinompatientinnen und den TOP2A-Amplifikationsstatus zu untersuchen. Methoden: Die Bavarian Breast Cancer Cases and Controls Studie (BBCC) ist eine prospektive Kohortenstudie zur Untersuchung von Risiko- und Prognosefaktoren bei Mammakarzinompatientinnen. Von den meisten Patientinnen sind Biomaterialien wie Keimbahn-DNA und Tumorgewebe verfügbar. An Keimbahn-DNA wurde der Single Nucleotide Polymorphism (SNP) rs13695 in der 3´UTR-Region von TOP2A mittels quantitativer Real-Time-PCR genotypisiert. Zur Bestimmung des Amplifikationsstatus des TOP2A-Gens wurde ein Tissue Microarray aus in Formalin fixiertem, in Paraffin eingebettetem Tumormaterial hergestellt und mittels fluoreszierender in situ Hybridisierung die Genkopienzahl von HER2 und TOP2A quantifiziert. Diese molekularen Marker wurden untereinander und mit der Prognose des Mammakarzinoms assoziiert. Ergebnisse: Insgesamt 1.276 Patientinnen konnten für den SNP rs13695 genotypisiert werden. Der homozygote CC-Genotyp war bei 736 Patientinnen (57,7 %) vorhanden, der heterozygote CT- und der homozygote TT-Genotyp konnte in 459 (36 %) bzw. in 81 (6 %) Patientinnen gefunden werden. Für Patientinnen, die eine Chemotherapie erhalten hatten, konnte in der multivariaten Überlebensanalyse gezeigt werden, dass der Genotyp ein unabhängiger prognostischer Faktor war. Die adjustierte Hazards Ratio (HR) pro T-Allel betrug 1,69 (95 % Konfidenzintervall: 1,14 bis 2,51; p = 0,009). Für Patientinnen, die keine Chemotherapie erhalten hatten, war der Genotyp nicht von prognostischer Relevanz. Die Bestimmung der Genkopienzahl von TOP2A im Tumor war in 629 Fällen durchführbar. 587 Patientinnen (93,3 %) hatten eine normale Genkopienzahl, 33 Patientinnen zeigten eine Amplifikation (5,2 %) und bei 9 Patientinnen war TOP2A im Tumor deletiert (1,4 %). Bei der Untersuchung der Assoziation zwischen dem Genotyp rs13695 und dem Amplifikationsstatus von TOP2A konnte gesehen werden, dass der Anteil der amplifizierten Patientinnen mit dem T-Allel zunimmt. Bei Patientinnen mit dem homozygoten CC-Genotyp zeigte sich in nur 3,9 % der Fälle eine Amplifikation, während diese bei heterozygotem CT- und homozygotem TT-Genotyp in 6,8 % bzw. 9,7% der Tumoren gesehen werden konnte (p = 0,042). Schlussfolgerung: Der TOP2A Genotyp in Bezug auf den SNP rs13695 scheint bei Mammakarzinompatientinnen, die eine Chemotherapie erhalten, eine unabhängige prognostische Bedeutung zu haben. Des Weiteren scheint der Genotyp mit dem Amplifikationsstatus dieses Gens assoziiert zu sein. Die kausale Beziehung zwischen dem Keimbahngenotyp, dem Amplifikationsstatus und der Prognose ist noch unklar und sollte Bestandteil weiterer Untersuchungen sein.Background and hypothesis: The amplification status of the gene Topoisomerase IIα (TOP2A) is a known predictive factor in breast cancer patients, who are treated with anthracycline chemotherapy. TOP2A is located on Chromosome 17q21. Topoisomerase IIα plays a key role in DNA replication and repairing. Furthermore it is the molecular target of anthracycline chemotherapies. Several studies could associate TOP2A gene amplification or deletion with an altered response to anthracycline chemotherapy. It is never amplified without a coamplification of the HER2 gene, which is located on the same chromosome. However in most of the cases HER2 is amplified without TOP2A. Aim of this study was therefore to examine whether genetic polymorphisms in the TOP2A gene are prognostic factors in breast cancer patients and whether the genotype is correlated with the TOP2A amplification status of the tumor. Methods: The Bavarian Breast Cancer Cases and Controls study (BBCC) is a prospective cohort study, which aims at researching breast cancer risk and prognostic factors. Biomaterials such as germline DNA and tumor tissue is available from most of the patients. Real-time-PCR was performed in order to genotype the single nucleotide polymorphism (SNP) rs13695 in the 3’UTR region of the TOP2A gene. Amplification of the TOP2A gene was quantified by fluorescent in situ hybridization (FISH) of the same patients. The tumours were available as a tissue microarray (TMA), which was constructed from paraffin embedded tumours. Genotyping results were analyzed concerning their prognostic relevance in this breast cancer patient cohort and genotype and amplification status were associated with each other. Results: The genotype of the SNP rs13695 could be ascertained of 1.276 patients. A homozygous genotype CC could be seen in 736 patients (57,7 %), the heterozygous CT genotype and the homozygous alternative genotype TT was present in 459 (36 %) and 81 (6 %) patients respectively. In the multivariate survival analysis the genotype of rs13695 was statistically only significant in patients who received an adjuvant chemotherapy with an adjusted hazards ratio per allele of 1,69 (95 % confidence interval CI: 1,14 to 2,51; p = 0,009). In patients who did not receive a chemotherapy the genotype had no prognostic relevance at all. FISH results for gene copy number variation analysis were available of 629 patients. 587 (93,3 %) patients had a normal gene copy number of TOP2A, 33 patients (5,2 %) and 9 patients (1,4 %) showed an amplification or a deletion. Associating the rs13695 genotype with the amplification status of TOP2A, an increasing proportion of tumors with an amplification was seen with each T allele. Patients with a CC genotype had an amplification of the TOP2A in the tumor in 3,9 % of all cases and in 6,8 % and 9,7 % for the CT and the TT genotype respectively (p = 0,042). Conclusion: The genotype of the SNP rs13695 seems to be of independent prognostic relevance in breast cancer patients, who are treated with a chemotherapy. Furthermore the genotype was correlated with the gene amplification status in the tumor. The reason for this observation remains unclear. Further evaluation of the SNP as prognostic factor and the association with the amplification status are to be subject to further investigation

Associations of breast cancer risk factors with tumor subtypes: a pooled analysis from the Breast Cancer Association Consortium studies.

BackgroundPrevious studies have suggested that breast cancer risk factors are associated with estrogen receptor (ER) and progesterone receptor (PR) expression status of the tumors.MethodsWe pooled tumor marker and epidemiological risk factor data from 35,568 invasive breast cancer case patients from 34 studies participating in the Breast Cancer Association Consortium. Logistic regression models were used in case-case analyses to estimate associations between epidemiological risk factors and tumor subtypes, and case-control analyses to estimate associations between epidemiological risk factors and the risk of developing specific tumor subtypes in 12 population-based studies. All statistical tests were two-sided.ResultsIn case-case analyses, of the epidemiological risk factors examined, early age at menarche (≤12 years) was less frequent in case patients with PR(-) than PR(+) tumors (P = .001). Nulliparity (P = 3 × 10(-6)) and increasing age at first birth (P = 2 × 10(-9)) were less frequent in ER(-) than in ER(+) tumors. Obesity (body mass index [BMI] ≥ 30 kg/m(2)) in younger women (≤50 years) was more frequent in ER(-)/PR(-) than in ER(+)/PR(+) tumors (P = 1 × 10(-7)), whereas obesity in older women (>50 years) was less frequent in PR(-) than in PR(+) tumors (P = 6 × 10(-4)). The triple-negative (ER(-)/PR(-)/HER2(-)) or core basal phenotype (CBP; triple-negative and cytokeratins [CK]5/6(+) and/or epidermal growth factor receptor [EGFR](+)) accounted for much of the heterogeneity in parity-related variables and BMI in younger women. Case-control analyses showed that nulliparity, increasing age at first birth, and obesity in younger women showed the expected associations with the risk of ER(+) or PR(+) tumors but not triple-negative (nulliparity vs parity, odds ratio [OR] = 0.94, 95% confidence interval [CI] = 0.75 to 1.19, P = .61; 5-year increase in age at first full-term birth, OR = 0.95, 95% CI = 0.86 to 1.05, P = .34; obesity in younger women, OR = 1.36, 95% CI = 0.95 to 1.94, P = .09) or CBP tumors.ConclusionsThis study shows that reproductive factors and BMI are most clearly associated with hormone receptor-positive tumors and suggest that triple-negative or CBP tumors may have distinct etiology

Associations of breast cancer risk factors with tumor subtypes: a pooled analysis from the breast cancer association consortium studies

Background Previous studies have suggested that breast cancer risk factors are associated with estrogen receptor (ER) and progesterone receptor (PR) expression status of the tumors. Methods We pooled tumor marker and epidemiological risk factor data from 35 568 invasive breast cancer case patients from 34 studies participating in the Breast Cancer Association Consortium. Logistic regression models were used in case-case analyses to estimate associations between epidemiological risk factors and tumor subtypes, and case-control analyses to estimate associations between epidemiological risk factors and the risk of developing specific tumor subtypes in 12 population-based studies. All statistical tests were two-sided. Results In case-case analyses, of the epidemiological risk factors examined, early age at menarche (<= 12 years) was less frequent in case patients with PR- than PR+ tumors (P = .001). Nulliparity (P = 3 x 10(-6)) and increasing age at first birth (P = 2 x 10(-9)) were less frequent in ER- than in ER+ tumors. Obesity (body mass index [BMI] >= 30 kg/m(2)) in younger women (<= 50 years) was more frequent in ER /PR than in ER+/PR+ tumors (P = 1 x 10(-7)), whereas obesity in older women (>50 years) was less frequent in PR- than in PR+ tumors (P = 6 x 10(-4)). The triple-negative (ER-/PR-/HER2-) or core basal phenotype (CBP; triple-negative and cytokeratins [CK]5/6(+) and/ or epidermal growth factor receptor [EGFR] 1) accounted for much of the heterogeneity in parity-related variables and BMI in younger women. Case-control analyses showed that nulliparity, increasing age at first birth, and obesity in younger women showed the expected associations with the risk of ER+ or PR+ tumors but not triple-negative (nulliparity vs parity, odds ratio [OR] = 0.94, 95% confidence interval [CI] = 0.75 to 1.19, P = .61; 5-year increase in age at first full-term birth, OR = 0.95, 95% CI = 0.86 to 1.05, P = .34; obesity in younger women, OR = 1.36, 95% CI = 0.95 to 1.94, P = .09) or CBP tumors. Conclusions This study shows that reproductive factors and BMI are most clearly associated with hormone receptor-positive tumors and suggest that triple-negative or CBP tumors may have distinct etiology

Associations of Breast Cancer Risk Factors With Tumor Subtypes: A Pooled Analysis From the Breast Cancer Association Consortium Studies

BACKGROUND: Previous studies have suggested that breast cancer risk factors are associated with estrogen receptor (ER) and progesterone receptor (PR) expression status of the tumors.METHODS: We pooled tumor marker and epidemiological risk factor data from 35,568 invasive breast cancer case patients from 34 studies participating in the Breast Cancer Association Consortium. Logistic regression models were used in case-case analyses to estimate associations between epidemiological risk factors and tumor subtypes, and case-control analyses to estimate associations between epidemiological risk factors and the risk of developing specific tumor subtypes in 12 population-based studies. All statistical tests were two-sided.RESULTS: In case-case analyses, of the epidemiological risk factors examined, early age at menarche (?12 years) was less frequent in case patients with PR(-) than PR(+) tumors (P = .001). Nulliparity (P = 3 × 10(-6)) and increasing age at first birth (P = 2 × 10(-9)) were less frequent in ER(-) than in ER(+) tumors. Obesity (body mass index [BMI] ? 30 kg/m(2)) in younger women (?50 years) was more frequent in ER(-)/PR(-) than in ER(+)/PR(+) tumors (P = 1 × 10(-7)), whereas obesity in older women (&gt;50 years) was less frequent in PR(-) than in PR(+) tumors (P = 6 × 10(-4)). The triple-negative (ER(-)/PR(-)/HER2(-)) or core basal phenotype (CBP; triple-negative and cytokeratins [CK]5/6(+) and/or epidermal growth factor receptor [EGFR](+)) accounted for much of the heterogeneity in parity-related variables and BMI in younger women. Case-control analyses showed that nulliparity, increasing age at first birth, and obesity in younger women showed the expected associations with the risk of ER(+) or PR(+) tumors but not triple-negative (nulliparity vs parity, odds ratio [OR] = 0.94, 95% confidence interval [CI] = 0.75 to 1.19, P = .61; 5-year increase in age at first full-term birth, OR = 0.95, 95% CI = 0.86 to 1.05, P = .34; obesity in younger women, OR = 1.36, 95% CI = 0.95 to 1.94, P = .09) or CBP tumors.CONCLUSIONS: This study shows that reproductive factors and BMI are most clearly associated with hormone receptor-positive tumors and suggest that triple-negative or CBP tumors may have distinct etiology.<br/

Associations of breast cancer risk factors with tumor subtypes: a pooled analysis from the breast cancer association consortium studies

BACKGROUND: Previous studies have suggested that breast cancer risk factors are associated with estrogen receptor (ER) and progesterone receptor (PR) expression status of the tumors.METHODS: We pooled tumor marker and epidemiological risk factor data from 35,568 invasive breast cancer case patients from 34 studies participating in the Breast Cancer Association Consortium. Logistic regression models were used in case-case analyses to estimate associations between epidemiological risk factors and tumor subtypes, and case-control analyses to estimate associations between epidemiological risk factors and the risk of developing specific tumor subtypes in 12 population-based studies. All statistical tests were two-sided.RESULTS: In case-case analyses, of the epidemiological risk factors examined, early age at menarche (?12 years) was less frequent in case patients with PR(-) than PR(+) tumors (P = .001). Nulliparity (P = 3 × 10(-6)) and increasing age at first birth (P = 2 × 10(-9)) were less frequent in ER(-) than in ER(+) tumors. Obesity (body mass index [BMI] ? 30 kg/m(2)) in younger women (?50 years) was more frequent in ER(-)/PR(-) than in ER(+)/PR(+) tumors (P = 1 × 10(-7)), whereas obesity in older women (&gt;50 years) was less frequent in PR(-) than in PR(+) tumors (P = 6 × 10(-4)). The triple-negative (ER(-)/PR(-)/HER2(-)) or core basal phenotype (CBP; triple-negative and cytokeratins [CK]5/6(+) and/or epidermal growth factor receptor [EGFR](+)) accounted for much of the heterogeneity in parity-related variables and BMI in younger women. Case-control analyses showed that nulliparity, increasing age at first birth, and obesity in younger women showed the expected associations with the risk of ER(+) or PR(+) tumors but not triple-negative (nulliparity vs parity, odds ratio [OR] = 0.94, 95% confidence interval [CI] = 0.75 to 1.19, P = .61; 5-year increase in age at first full-term birth, OR = 0.95, 95% CI = 0.86 to 1.05, P = .34; obesity in younger women, OR = 1.36, 95% CI = 0.95 to 1.94, P = .09) or CBP tumors.CONCLUSIONS: This study shows that reproductive factors and BMI are most clearly associated with hormone receptor-positive tumors and suggest that triple-negative or CBP tumors may have distinct etiology.<br/