Xiaoan Liu

Genistein inhibits MDA-MB-231 triple-negative breast cancer cell growth by inhibiting NF-κB activity via the Notch-1 pathway.

Genistein (Gen) has been reported as a protective factor against breast cancer. However, the molecular mechanism by which Gen elicits its effects on triple-negative breast cancer cells has not been fully elucidated. In our study, the breast cancer cell line MDA-MB-231 was selected to determine the action of Gen on triple-negative breast cancer cells. MTT assay, flow cytometric analysis, siRNA transfection, western blotting and nuclear factor-κB (NF-κB) activation-nuclear translocation assay were used to address the role of NF-κB activity and the Notch-1 signaling pathway on the effects of Gen. Our study revealed that Gen elicited a dramatic effect on cell growth inhibition, in a dose-dependent and time-dependent manner. Treatment of MDA-MB-231 cells with 0, 5, 10 or 20 µM Gen induced apoptosis of 6.78, 18.98, 30.45 and 60.64%, respectively. Exposure of MDA-MB-231 cells to Gen also resulted in G2/M phase accumulation of cells corresponding to 4.93, 12.54, 18.93 and 30.95%, respectively. Furthermore, our data demonstrated for the first time that Gen inhibited the growth of MDA-MB-231 triple-negative breast cancer cells by inhibiting NF-κB activity via the Nocth-1 signaling pathway in a dose-dependent manner. We also found that Gen downregulated the expression of cyclin B1, Bcl-2 and Bcl-xL, possibly mediated by NF-κB activation via the Notch-1 signaling pathway. In conclusion, our results suggest that inhibition of NF-κB activity via the Notch-1 pathway may be a novel mechanism by which Gen suppresses the growth of triple-negative breast cancer cells. Further preclinical and clinical studies are warranted to further investigate the application of Gen for the treatment of triple-negative breast cancer.

US-guided Percutaneous Microwave Coagulation of Small Breast Cancers: A Clinical Study

PURPOSE To determine the feasibility of percutaneous microwave coagulation (PMC) for the treatment of small solitary breast cancers. MATERIALS AND METHODS With approval of the institutional ethics committee and written informed consent, 41 patients with core-needle-biopsy-proved breast cancers 3.0 cm or less in diameter accessed by using ultrasonography (US) were recruited. US-guided PMC was performed with general anesthesia, followed immediately by mastectomy. Histochemical staining with α-nicotinamide adenine dinucleotide, reduced (NADH)-diaphorase was used to determine cell viability and the extent of PMC lesions. RESULTS The mean tumor volume was 5.26 cm(3) ± 3.80 (standard deviation), with a range from 0.09 to 14.14 cm(3). PMC was successfully performed in all cases, with complete tumor ablation as assessed by using US. The mean time to reach complete ablation was 4.48 minutes, ranging from 3 to 10 minutes. With microscopic examination, 37 of 41 cases (90%; 95% confidence interval [CI]: 76.9%, 97.3%) showed complete tumor coagulation, as observed by using α-NADH-diaphorase staining. Of 38 cases diagnosed with invasive ductal carcinoma, 36 cases (95%; 95% CI: 82.3%, 99.4%) showed complete tumor coagulation. Slight thermal injuries to the skin and pectoralis major muscle, which proved reversible, were found in three cases. CONCLUSION US-guided PMC of small solitary breast cancers is feasible. Nevertheless, larger-scale clinical trials are still needed to validate PMC for adoption into a standard clinical practice.

Downregulation of miR-106b induced breast cancer cell invasion and motility in association with overexpression of matrix metalloproteinase 2

Breast cancer (BC) is one of the most common cancers in women, and it can often metastasize to the bone. The mechanism of BC bone metastasis remains unclear and requires in‐depth investigation. In a previous study, we found the expression of matrix metalloproteinase 2 (MMP2) to be significantly more pronounced at metastatic bone sites than at orthotopic sites. MicroRNA expression profiling showed miR‐106b to be markedly downregulated during BC bone metastasis. However, the specific manner in which MMP2 and miR‐106b are involved in the BC bone metastasis is still unclear. In the present study, we found MMP2 expression in orthotopic tumor tissue to be related to the risk of bone metastasis in BC patients. MiR‐106b levels in orthotopic tumor tissue showed a negative correlation with MMP2 expression and breast cancer bone metastasis. MMP2 was shown to be a direct target of miR‐106b. Both gain‐ and loss‐of‐function studies showed that MMP2 could promote the migration and invasion of BC cells and that miR‐106b could suppress both. The blockage of MMP2 by RNA interference mimicked the anti‐migration and anti‐invasion effects of miR‐106b, and introduction of MMP2 antagonized the function of miR‐106b. MMP2 was also found to regulate the ERK signaling cascade and so adjust the bone microenvironment to favor osteoclastogenesis and bone metastasis. These results suggest that MMP2 upregulation plays an important role in BC bone metastasis through ERK pathways, and miR‐106b directly regulates MMP2 expression. The miR‐106b/MMP2/ERK pathway may be a promising therapeutic target for inhibiting BC bone metastasis.

Evaluation of genetic variants in microRNA biosynthesis genes and risk of breast cancer in Chinese women.

MicroRNAs (miRNA) are a class of small, noncoding RNA molecules involved in a diversity of cellular functions. Single nucleotide polymorphisms (SNPs) in miRNA biosynthesis genes may affect the biogenesis of miRNAs and consequently affect the miRNAs regulation. In this study, we systematically selected 24 functional SNPs located in eight key biosynthesis genes of miRNA (DROSHA, DGCR8, RAN, DICER, AGO2, GEMIN3, GEMIN4 and HIWI) and investigated the association between these SNPs and the risk of breast cancer in a Chinese population. All 24 SNPs were firstly genotyped in stage 1 (878 cases and 900 controls) and three promising SNPs (DROSHA rs2291109, RAN rs7301722 and DGCR8 rs417309) were selected for further validation in stage 2 (914 cases and 967 controls). We found that only one SNP (rs417309) located in the 3′‐UTR of DGCR8 was consistently associated with an increased breast cancer risk in two stages with a combined odds ratio (OR) of 1.50 [95% confidence interval (CI) = 1.16–1.93]. Based on the bioinformatics prediction, rs417309 is located at the binding sites of miR‐106b and miR‐579 in the 3′‐UTR of DGCR8. To evaluate whether rs417309 variant affects the binding capacity of miRNAs, we cotransfected luciferase reporter plasmids of DGCR8 3′‐UTR and miR‐106b/miR‐579 in three cell lines. Luciferase activity assay showed a higher expression level with rs417309 A allele compared with G allele in MCF‐7 cell lines (p = 3.31 × 10–7, 9.29 × 10–7 for miR‐106b and miR‐579, respectively). Our findings suggested that DGCR8 rs417309 G > A might affect breast cancer risk through the interruption of miRNA binding.

STAT3 mediates resistance of CD44+CD24−/low breast cancer stem cells to tamoxifen in vitro

We sought to determine whether STAT3 mediated tamoxifen resistance of breast cancer stem cells in vitro. The capacities for mammosphere formation and STAT3 expression of CD44+CD24−/low MCF-7 and MCF-7 were observed. The CD44+CD24−/low subpopulation ratio and its sensitivity to adriamycin were analyzed in MCF-7 and TAM resistant (TAM-R) cells. Cell cycle, apoptosis, STAT3 and phospho-STAT3 changes were observed after treatment with tamoxifen. Small interference RNA-mediated knockdown of STAT3 in TAM-R cells was also performed. CD44+CD24−/low MCF-7 showed higher capacities for mammosphere formation and STAT3 expression than total MCF-7. The CD44+CD24−/low subpopulation was also upregulated in TAM-R cells with less sensitivity to adriamycin than MCF-7. Cell cycle changes, anti-apoptotic effects and STAT3 changes were also found. Meanwhile, the knock-down of STAT3 in TAM-R resulted in an increase in sensitivity to tamoxifen. It is concluded that STAT3 plays an essential role in breast cancer stem cells, which correlated with tamoxifen resistance.

Intraoperative ultrasound guidance is associated with clear lumpectomy margins for breast cancer: a systematic review and meta-analysis.

Purpose Margin status is one of the most important predictors of local recurrence after breast conserving surgery (BCS). Intraoperative ultrasound guidance (IOUS) has the potential to improve surgical accuracy for breast cancer. The purpose of the present meta-analysis was to determine the efficacy of IOUS in breast cancer surgery and to compare the margin status to that of the more traditional Guide wire localization (GWL) or palpation-guidance. Methods We searched the database of PubMed for prospective and retrospective studies about the impact of IOUS on margin status of breast cancer, and a meta-analysis was conducted. Results Of the 13 studies included, 8 were eligible for the impact of IOUS on margin status of non-palpable breast cancers, 4 were eligible for palpable breast cancers, and 1 was for both non-palpable and palpable breast cancers. The rate of negative margins of breast cancers in IOUS group was significantly higher than that in control group without IOUS (risk ratio (RR)  = 1.37, 95% confidence interval (CI)  = 1.18–1.59 from 7 prospective studies, odds ratio (OR)  = 2.75, 95% CI  = 1.66–4.55 from 4 retrospective studies). For non-palpable breast cancers, IOUS-guidance enabled a significantly higher rate of negative margins than that of GWL-guidance (RR  = 1.26, 95% CI  = 1.09–1.46 from 6 prospective studies; OR  = 1.45, 95% CI  = 0.86–2.43 from 2 retrospective studies). For palpable breast cancers, relative to control group without IOUS, the RR for IOUS associated negative margins was 2.36 (95% CI  = 1.26–4.43) from 2 prospective studies, the OR was 2.71 (95% CI  = 1.25–5.87) from 2 retrospective studies. Conclusion This study strongly suggests that IOUS is an accurate method for localization of non-palpable and palpable breast cancers. It is an efficient method of obtaining high proportion of negative margins and optimum resection volumes in patients undergoing BCS.

Potentially functional polymorphisms in ATG10 are associated with risk of breast cancer in a Chinese population.

Autophagy is a cellular process directed at recycling of cellular proteins and removal of intracellular microorganisms, which is important for balancing sources of energy at critical times in development and in response to nutrient stress. It has been reported to be a critical process in cancer initiation and progression. We hypothesized that genetic variants in critical genes of autophagy may be involve in the development of breast cancer. Thus, we systematically screened 14 potentially functional polymorphisms in six autophagy-related genes (ATG3, ATG5, ATG7, ATG10, and ATG12 and LC3) that are core components in autophagosome formation. We conducted a case-control study including 1064 breast cancer cases and 1073 cancer-free controls to evaluate the associations of these variants with breast cancer risk. We found that rs1864182 and rs10514231 in ATG10 were significantly associated with a decreased risk of breast cancer [odds ratios (OR)=0.77, 95% confidence interval (CI): 0.61-0.96, P=0.023; and OR=0.75, 95% CI: 0.59-0.93, P=0.010, respectively]. Similar protective effects for both loci were observed between subgroups stratified by ages at diagnosis/recruitment, menarche and first live birth, and status of menopause, estrogen receptor (ER) and progesterone receptor (PR). These results suggest that genetic variants in ATG10 may implicate with breast cancer susceptibility in Chinese population. Further large and functional studies are needed to confirm our findings.

Molecular subtype classification is a determinant of non-sentinel lymph node metastasis in breast cancer patients with positive sentinel lymph nodes.

Background Previous studies suggested that the molecular subtypes were strongly associated with sentinel lymph node (SLN) status. The purpose of this study was to determine whether molecular subtype classification was associated with non-sentinel lymph nodes (NSLN) metastasis in patients with a positive SLN. Methodology and Principal Findings Between January 2001 and March 2011, a total of 130 patients with a positive SLN were recruited. All these patients underwent a complete axillary lymph node dissection. The univariate and multivariate analyses of NSLN metastasis were performed. In univariate and multivariate analyses, large tumor size, macrometastasis and high tumor grade were all significant risk factors of NSLN metastasis in patients with a positive SLN. In univariate analysis, luminal B subgroup showed higher rate of NSLN metastasis than other subgroup (P = 0.027). When other variables were adjusted in multivariate analysis, the molecular subtype classification was a determinant of NSLN metastasis. Relative to triple negative subgroup, both luminal A (P = 0.047) and luminal B (P = 0.010) subgroups showed a higher risk of NSLN metastasis. Otherwise, HER2 over-expression subgroup did not have a higher risk than triple negative subgroup (P = 0.183). The area under the curve (AUC) value was 0.8095 for the Cambridge model. When molecular subtype classification was added to the Cambridge model, the AUC value was 0.8475. Conclusions Except for other factors, molecular subtype classification was a determinant of NSLN metastasis in patients with a positive SLN. The predictive accuracy of mathematical models including molecular subtype should be determined in the future.

Reproductive factors and breast cancer risk among BRCA1 or BRCA2 mutation carriers: Results from ten studies

Although reproductive factors are among the most well-established risk factors for breast cancer in the general population, it is still a matter for debate whether these factors act as risk modifiers among BRCA1 or BRCA2 mutation carriers. This meta-analysis is the first to be performed to determine the relationship between reproductive factors and breast cancer risk among BRCA1 and BRCA2 mutation carriers. We searched the PubMed database up to February 2013. A total of ten studies met the inclusion criteria. The results showed that the reproductive factors may be associated with breast cancer risk only among BRCA1 mutation carriers. No association was found between parity and breast cancer risk. Compared with women at the youngest age in the first-birth category, women in the oldest age category were at a 38% lower risk of breast cancer (RR=0.62, 95%CI=0.45-0.85). Breastfeeding for at least 1 or 2 years was associated with a 37% reduction in breast cancer risk (RR=0.63, 95%CI=0.46-0.86). Women at the oldest age in the menarche category were at a 34% lower risk of breast cancer (RR=0.66, 95%CI=0.53-0.81) than women in the youngest age category. However, none of the reproductive factors were associated with breast cancer risk among BRCA2 mutation carriers. In conclusion, late age at first birth, breastfeeding, and late age at menarche protect against breast cancer in BRCA1 mutation carriers only. Further studies are needed to explore the mechanisms.

Comparison of Ablation Zones among Different Tissues Using 2450-MHz Cooled-Shaft Microwave Antenna: Results in Ex Vivo Porcine Models

Background For complete tumor ablation in different tissues, it is necessary to investigate the exact coagulation zone of microwave ablation in different tissues. The aim of this study was to compare the extent of microwave ablation zone in muscle, liver and adipose tissue in ex vivo porcine models and assess the shape of microwave coagulation zone among these tissues. Materials and Methods Microwave ablations were performed in ex vivo porcine muscle, liver and adipose tissue using 2450-MHz cooled-shaft microwave antenna. The content of water, fat and protein in these three tissues was determined. Two power increments (40 and 80 W) and five time increments (1, 3, 5, 7, and 10 minutes) were used in this study. Diameters and shapes of the ablation zones were assessed on gross specimens. Results The average percentages of water, fat and protein in these three tissues were significantly different (P < 0.001), respectively. The long-axis and short-axis diameters among these three tissues at each time-power combination were not significantly different (P > 0.05). The coagulation zones were all elliptical in muscle, liver and adipose tissue. When microwave ablation was performed in the tissue containing both muscle and adipose tissue, the coagulation zone was also elliptical. Regardless of the output power, the ellipticity index (EI) value of 1 minute treatment duration was higher than that of 10 minutes treatment duration (P < 0.05). Furthermore, the EI value did not decrease significantly when the treatment duration was more than 5 minutes (P > 0.05). Conclusion The extent of microwave ablation zones was not significantly different among completely different tissues. Microwave ablations with ≥ 5 minutes time duration can induce coagulation zones with clinical desirable shape. Future clinical studies are still required to determine the role of microwave ablation in different tissues.