Relationships of physical and breast cancer phenotypes with three single-nucleotide polymorphisms (rs2046210, rs3757318, and rs3803662) associated with breast cancer risk in Japanese women.

BACKGROUND: Recent genome-wide association studies have shown that many single-nucleotide polymorphisms (SNPs) are associated with breast cancer risk. However, it is often unclear how these SNPs are related to breast cancer. Analysis of associations between SNPs and phenotypes may be important for determining mechanisms of action, including carcinogenesis. METHODS: In previous case-control studies, we found three SNPs (rs2046210, rs3757318, and rs3573318) associated with breast cancer risk in Japanese women. Among these SNPs, two (rs2046210 and rs3757318) are located at 6q25.1, in proximity to the estrogen receptor 1 gene (ESR1). Using data from these studies, we examined associations between factors related to breast cancer risk, such as height, weight, and breast density, and the three SNPs in cases and controls. We also investigated whether the SNPs correlated with breast cancer features, such as estrogen receptor (ER), progesterone receptor (PgR), and human epidermal growth factor receptor type-2 (HER2) status, and clinical stage. RESULTS: There was a significant difference in mean height between risk and non-risk allele carriers for rs2046210 (156.0 ± 5.8 vs. 154.3 ± 5.5 cm, p = 0.002), and rs3757318 (155.8 ± 5.7 vs. 154.7 ± 5.6 cm, p = 0.035) in cases, but no significant associations between height and these SNPs in controls. There was also a significant difference in breast density between risk and non-risk allele carriers for rs2046210 (p = 0.040) and rs3757318 (p = 0.044) in cases. rs2046210 and rs3757318 risk allele carriers tended to have higher breast density in all subjects and in controls. In cases, rs3757318 risk allele carriers were also significantly more likely to be ER-negative compared to non-risk allele carriers (ER-positive rate: 77% vs. 84%, p = 0.036). CONCLUSIONS: SNPs rs2046210 and rs3757318, which are associated with breast cancer risk in Japanese women, were significantly associated with height and high breast density, and this association was particularly strong in those with breast cancer. These findings suggest that SNPs in the ESR1 gene region affect phenotypes such as height and breast density.

Influence of breast density on breast cancer risk: a case control study in Japanese women.

BACKGROUND: Mammography is the standard examination for breast cancer screening of woman aged ≥ 40 years. High breast density on mammography indicates that mammary gland parenchyma occupy a high percentage of the breast. The objective of this study was to investigate factors associated with breast density and the risk of high breast density for breast cancer. METHODS: A multicenter case-control study was performed in 530 patients and 1043 controls. Breast density was classified as C1-C4 using the Breast Imaging Reporting and Data System (BI-RADS). Clinical factors were obtained from questionnaires or medical records, and the influence of each factor (breast density, menopausal status, body mass index (BMI), parity, presence or absence of breastfeeding history, age at menarche, age at first birth, and familial history of breast cancer) on breast cancer risk in all patients was calculated as an age-adjusted odds ratio (OR). Multivariate logistic regression analyses were then performed in all patients and in pre- and postmenopausal and BMI-stratified groups using factors with a significant age-adjusted OR as adjustment factors. RESULTS: Age-adjusted ORs for breast cancer were significant for breast density, BMI, parity, and breast feeding, but not for age at menarche, age at first birth, or family history of breast cancer. In multivariate analysis, there was a significant correlation between breast density and breast cancer in postmenopausal women (OR for C1 vs. C2 1.90 [95% CI 1.34-2.70]; C1 vs. C4 2.85 [95% CI 1.10-7.16]). This correlation was also significant in patients in the third BMI quartile (22.3-24.5 kg/m2) (OR for C1 vs. C4 8.76 [95% CI 2.38-42.47]); and fourth BMI quartile (>24.5 kg/m2) (OR for C1 vs. C2 1.92 [95% CI 1.17-3.15]; C1 vs. C4 11.89 [95% CI 1.56-245.17]). CONCLUSION: Breast density on mammography is a risk factor for breast cancer after adjustment for other risk factors. This risk is particularly high in postmenopausal women and those with a high BMI.

Tumor inhibitory effect of gefitinib (ZD1839, Iressa) and taxane combination therapy in EGFR-overexpressing breast cancer cell lines (MCF7/ADR, MDA-MB-231).

Some kinds of breast cancer cell lines, similar to several types of solid tumors, express epidermal growth factor receptor (EGFR). However, gefitinib, an EGFR tyrosine kinase inhibitor, is not effective for all these cell lines. Similarly, taxane is effective for many of the cell lines, although some, such as the multidrug-resistant MCF7/ADR cell line, show taxane-resistance. Here, we examined the growth inhibitory effect of combination treatment with gefitinib and taxane on the breast cancer cell lines MDA-MB-231 (EGFR-positive) and MCF7/ADR (EGFR- and HER2-positive). To estimate the combined effect, a Combination Index was calculated for each cell line. The combination of gefitinib and taxane showed a strong synergistic effect on MCF7/ADR cells, but an invitro additive-antagonistic effect on MDA-MB-231 cells. Similarly, the combination treatment showed a significantly increased tumor inhibitory effect on MCF7/ADR xenografts, but not on MDA-MB-231 xenografts. Regarding the mechanism of the synergistic effect, Western blotting analysis revealed that taxane activated the EGFR-Akt pathway in MCF7/ADR cells but not in MDA-MB-231. To determine the optimal sequential administration of gefitinib and taxane for MCF7/ADR cells, we used flow cytometry to analyze the cell cycle and apoptosis; finding that taxane treatment followed by gefitinib produced a higher rate of G2 arrest and apoptosis than gefitinib treatment followed by taxane. These results suggest gefitinib overcomes the drug-resistance of these cells, thereby increasing the effects of taxane on MCF7/ADR cells. Further, activation of the EGFR-Akt pathway by taxane is related to this synergistic effect.

Multidetector row computed tomography for diagnosing intraductal extension of breast carcinoma.

OBJECTIVES: Several reports supported the association of higher ipsilateral breast tumor recurrence rates with positive or intermediate margins compared with negative pathologic margins. Precise evaluation of intraductal component and adequate surgical margin are important factors affecting the tumor recurrence after breast conserving surgery. Numerous studies have reported the utility of magnetic resonance imaging for diagnosing developing intraductal extension of breast cancer, but few have investigated multidetector-row computed tomography (MD-CT). The present study evaluated the clinical utility of MD-CT for detecting intraductal extension of breast carcinoma, and analyzed clinical parameters affecting the detection of intraductal extension under MD-CT. METHODS: Subjects comprised 44 patients grouped into three categories according to degree of intraductal extension of the main tumor under MD-CT (Intraductal spread grade 1 approximately 3: IDS 1 approximately 3). Tumors were also categorized histopathologically (p-IDS 0 approximately 3), and CT-pathological correlations were examined retrospectively. Clinical parameters were evaluated to determine the affect on detection of intraductal components. RESULTS: MD-CT detected 44 breast lesions (100%). Sensitivity for detection of intraductal component was 81.2%, specificity was 67.8%, and accuracy was 72.7%. Regarding extent of intraductal components, significant correlations were found between histopathological and MD-CT findings. A strong correlation was found in postmenopausal women between T2 tumor and high histological grade. CONCLUSIONS: MD-CT findings of intraductal extension from breast carcinoma correlate with histological degree of intraductal extension, and MD-CT may be useful for preoperative assessment of breast-conserving surgery, particularly for postmenopausal women with histological high nuclear grade and T2 tumor.

Proteasome inhibitors can alter the signaling pathways and attenuate the P-glycoprotein-mediated multidrug resistance.

Numerous signaling pathways were reported to be involved in the resistance for conventional cytotoxic drugs, although one of the main reasons is the overexpression of P-glycoprotein (P-gp) in multidrug resistant cancer cells. The overexpression of P-gp has been associated with the resistance to a wide range of anticancer drugs. Doxorubicin and paclitaxel are substrates of this transporter system and have an important role for the various human malignancies. In the present study, drug-sensitive MCF7 and multidrug resistant MCF7/ADR (characterized by overexpression of P-gp) human breast cancer cell lines were used as an experimental model. We have found that PS341 and MG132, proteasome inhibitors, reduced the degree of the multidrug resistance (MDR) in MCF7/ADR cells. This phenomenon was accompanied by a decrease in the IC50 value of doxorubicin and paclitaxel from 55.9 +/- 3.46 to 0.60 +/- 0.08 microM, and from 17.61 +/- 1.77 to 0.59 +/- 0.12 microM, respectively. The IC50 values of sensitive cells for doxorubicin and paclitaxel were about 0.42 and 0.83 microM, respectively. The effect of PS341 and MG132 on MCF7/ADR cells was associated with a significant decrease in both protein and gene levels of P-gp expression. Moreover, with regard to the expression of possible signal transduction pathways of mitogen-activated protein kinase (MAPK) related to the activation of mdr1, proteasome inhibitors did significantly influence the activation of these proteins. Western blot analysis revealed that 24 hr exposure of multidrug resistant MCF7/ADR cells with proteasome inhibitors did change the levels of DNA binding activity of nuclear factor-kappaB (NF-kappaB), pERK1/2, c-Jun, and p-c-Jun. In conclusion, we could remark that proteasome inhibitors (especially PS341) attenuate the resistance of MCF7/ADR cells for P-gp substrate drugs of doxorubicin and paclitaxel. Several proteins are supposed to be associated with the resensitization of the cells to conventional cytotoxic drugs, although decreased activity of P-gp is at least involved in the proteasome inhibitor-related resensitization. And influence with MAPK pathways, which have been reported to be associated with the regulation of P-gp, might be contributed to the resensitization brought by proteasome inhibitors.