Allelic loss on chromosome band 18p11.3 occurs early and reveals heterogeneity in breast cancer progression
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We examined the stage specificity and heterogeneity of 18p11 alterations in a series of tumors representing 96 microdissected samples. Significant loss of heterozygosity (LOH) (63%) was found, with 56% occurring early in ductal carcinoma in situ. Although most cases indicated LOH was clonally inherited, heterogeneity for 18p LOH occurred in 27% of tumors. When compared with other LOH data, 18p LOH was found in conjunction with allelic deletion on 3p, 9p, 17p and 17q, while 13q, 16q, and 11p were less frequently associated. These analyses suggest chromosome 18p11 alteration is a common and early event in breast disease.
In order to explore the possible role of E-cadherin in familial cancer, 19 familial breast cancer patients, whose tumours demonstrated loss of heterozygosity (LOH) at the E-cadherin locus, were screened for germline mutations. No pathogenic germline alterations were detected in these individuals. However, a somatic mutation was found (49-2A→C) in one of the tumours. This tumour showed a pattern of both ductal and lobular histology. Another 10 families with cases of breast, gastric and colon cancer were also screened for germline mutations, and no mutations were found. A missense mutation in exon 12 of E-cadherin (1774G→A; Ala592Thr) was previously found in one family with diffuse gastric cancer, and colon and breast cancer. An allelic association study was performed to determine whether the Ala592Thr alteration predisposes to breast cancer. In total, we studied 484 familial breast cancer patients, 614 sporadic breast cancer patients and 497 control individuals. The frequencies of this alteration were similar in these groups. However, a correlation between the Ala592Thr alteration and ductal comedo-type tumour was seen. These results, together with previously reported studies, indicate that germline mutations and, more commonly, somatic mutations in E-cadherin may have an influence on the behaviour of the tumours, rather than predispose to breast cancer.
A49T, V89L and TA repeat polymorphisms of steroid 5α-reductase type II and breast cancer risk in Japanese women
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Background Breast cancer is hormone related, as are cancers of the endometrium, ovary, and prostate. Several studies have suggested that higher extracellular levels of androgens are associated with breast cancer risk, while biological evidence indicates that androgens are protective. The codon 49 alanine to threonine substitution (A49T), codon 89 valine to leucine substitution (V89L) and TA repeat polymorphisms of the steroid 5α-reductase type II (SRD5A2) gene are considered functional with respect to enzyme activity converting testosterone into dihydrotestosterone. To test the hypothesis that these three polymorphisms are associated with risk of breast cancer, a case–control study was conducted with patients of Aichi Cancer Center Hospital. Methods The cases were 237 patients histologically diagnosed with breast cancer, and the controls were 185 noncancer outpatients. DNA from peripheral blood was genotyped by PCR methods. Results The threonine allele of A49T was not found in our subjects. Compared with the V/V genotype of V89L, the L/L genotype was associated with a decreased risk (crude odds ratio [OR] = 0.61, 95% confidence interval [CI] = 0.36–1.05). This was also the case for the TA(9/9) genotype, with an OR of 0.58 (95% CI = 0.13–2.63) relative to TA(0/0). Among women with the TA(0/0) genotype, however, the OR for the L/L genotype was 0.46 (95% CI = 0.24–0.88) compared with the V/V genotype, and those with the V/V and TA(0/0) genotypes had the highest risk. The haplotype with the L and TA(9) repeat alleles was not found. Conclusion This study is the first to our knowledge focusing on Japanese women, suggesting that SRD5A2 polymorphisms might have an association with breast cancer risk. Further large-sample studies will be required to confirm the association and to assess any interactions with environmental factors.
Investigation of glutathione
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Background Certain genes from the glutathione S-transferase superfamily have been associated with several cancer types. It was the objective of this study to determine whether alleles of the glutathione S-transferase zeta 1 (GSTZ1) gene are associated with the development of sporadic breast cancer. Methods DNA samples obtained from a Caucasian population affected by breast cancer and a control population, matched for age and ethnicity, were genotyped for a polymorphism of the GSTZ1 gene. After PCR, alleles were identified by restriction enzyme digestion and results analysed by chi-square and CLUMP analysis. Results Chi-squared analysis gave a χ2 value of 4.77 (three degrees of freedom) with P = 0.19, and CLUMP analysis gave a T1 value of 9.02 with P = 0.45 for genotype frequencies and a T1 value of 4.77 with P = 0.19 for allele frequencies. Conclusion Statistical analysis indicates that there is no association of the GSTZ1 variant and hence the gene does not appear to play a significant role in the development of sporadic breast cancer.
The intronic G13964C variant in
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Background Mutations in BRCA1 and BRCA2 account for approximately 50% of breast cancer families with more than four affected cases, whereas exonic mutations in p53, PTEN, CHK2 and ATM may account for a very small proportion. It was recently reported that an intronic variant of p53 - G13964C - occurred in three out of 42 (7.1%) 'hereditary' breast cancer patients, but not in any of 171 'sporadic' breast cancer control individuals (P = 0.0003). If this relatively frequent occurrence of G13964C in familial breast cancer and absence in control individuals were confirmed, then this would suggest that the G13964C variant plays a role in breast cancer susceptibility. Method We genotyped 71 familial breast cancer patients and 143 control individuals for the G13964C variant using polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) analysis. Results Three (4.2%; 95% confidence interval [CI] 0–8.9%) G13964C heterozygotes were identified. The variant was also identified in 5 out of 143 (3.5%; 95% CI 0.6–6.4%) control individuals without breast cancer or a family history of breast cancer, however, which is no different to the proportion found in familial cases (P = 0.9). Conclusion The present study would have had 80% power to detect an odds ratio of 4.4, and we therefore conclude that the G13946C polymorphism is not a 'high-risk' mutation for familial breast cancer.
Datasets for Figures and Tables in SIX1 regulates aberrant endometrial epithelial cell differentiation and cancer trajectory
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Data associated with the figures presented in this study are images, graphics, or tabulated data based on histopathologic analysis performed by a certified study pathologist or image analysis. Data for Tables 1 and 2 provide incidence, labeling scores, and p-values for statistical tests for uterine pathology and IHC expression by treatment group and timepoint or human endometrial tissue, as described in the Main Text file of the manuscript. Manual histopathologic data can be found in excel spreadsheets and are based on presence/absences (yes/no) of a pathologic finding and/or severity score as described in the manuscript (Fig. 1, 2, 3, 4). The image analysis data is based on the quantified area that is designated as “positive” for a particular immunohistochemical stain (Fig. 2, 4, and Suppl. Fig. S2). Supplementary Table 1 provides summary information on antibodies used for immunohistochemistry. Supplementary fig. S1 includes real time RT-PCR data standardized to a housekeeping gene and western blot data. This dataset is associated with the following publication: Suen, A., W. Jefferson, C. Wood, and C. Williams. SIX1 regulates aberrant endometrial epithelial cell differentiation and cancer trajectory. Molecular Cancer Research. American Association for Cancer Research, Inc., Philadelphia, PA, USA, 17(12): 2369-2382, (2019).
Research Article: Breast Cancer Research : BCR
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Background Disruption of the balance between apoptosis and proliferation is considered to be an important factor in the development and progression of tumours. In the present study we determined the in vivo cell kinetics along the spectrum of apparently normal epithelium, hyperplasia, preinvasive lesions and invasive carcinoma, in breast tissues affected by fibrocystic changes in which preinvasive and/or invasive lesions developed, as a model of breast carcinogenesis. Materials and methods A total of 32 areas of apparently normal epithelium and 135 ductal proliferative and neoplastic lesions were studied. More than one epithelial lesion per case were analyzed. The apoptotic index (AI) and the proliferative index (PI) were expressed as the percentage of TdT-mediated dUTP-nick end-labelling (TUNEL) and Ki-67-positive cells, respectively. The PI/AI (P/A index) was calculated for each case. Results The AIs and PIs were significantly higher in hyperplasia than in apparently normal epithelium (P = 0.04 and P = 0.0005, respectively), in atypical hyperplasia than in hyperplasia (P = 0.01 and P = 0.04, respectively) and in invasive carcinoma than in in situ carcinoma (P < 0.001 and P < 0.001, respectively). The two indices were similar in atypical hyperplasia and in in situ carcinoma. The P/A index increased significantly from normal epithelium to hyperplasia (P = 0.01) and from preinvasive lesions to invasive carcinoma (P = 0.04) whereas it was decreased (non-significantly) from hyperplasia to preinvasive lesions. A strong positive correlation between the AIs and the PIs was found (r = 0.83, P < 0.001). Conclusion These findings suggest accelerating cell turnover along the continuum of breast carcinogenesis. Atypical hyperplasias and in situ carcinomas might be kinetically similar lesions. In the transition from normal epithelium to hyperplasia and from preinvasive lesions to invasive carcinoma the net growth of epithelial cells results from a growth imbalance in favour of proliferation. In the transition from hyperplasia to preinvasive lesions there is an imbalance in favour of apoptosis.