Long non-coding RNA SATB2-AS1 inhibits microRNA-155-3p to suppress breast cancer cell growth by promoting breast cancer metastasis suppressor 1-like.

BACKGROUND: Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) play vital roles in human cancers. Nevertheless, the effects of lncRNAs and miRNAs on breast cancer (BC) remain to be further investigated. This study was designed to testify the roles of lncRNA antisense transcript of SATB2 protein (SATB2-AS1) and microRNA-155-3p (miR-155-3p) in BC progression. METHODS: Levels of SATB2-AS1, miR-155-3p and breast cancer metastasis suppressor 1-like (BRMS1L) in BC were determined. The prognostic role of SATB2-AS1 in BC patients was assessed. The screened cells were respectively introduced with altered SATB2-AS1 or miR-155-3p to figure out their roles in malignant phenotypes of BC cells. The effect of varied SATB2-AS1 and miR-155-3p on BC cells in vivo was observed. Dual luciferase reporter gene assay and RNA-pull down assay were implemented to detect the targeting relationship of SATB2-AS1, miR-155-3p, and BRMS1L. RESULTS: SATB2-AS1 and BRMS1L were decreased while miR-155-3p was increased in BC cells and tissues. Patients with lower SATB2-AS1 expression had poor prognosis. Elevated SATB2-AS1 and inhibited miR-155-3p were able to restrain malignant behaviors of BC cells in vitro, as well as decelerate tumor growth in vivo. Oppositely, inhibited SATB2-AS1 and amplified miR-155-3p had converse effects on BC cell growth. MiR-155-3p mimic abrogated the impact of overexpressed SATB2-AS1. SATB2-AS1 could sponge miR-155-3p, and BRMS1L was the target gene of miR-155-3p. CONCLUSION: Elevated SATB2-AS1 and inhibited miR-155-3p could suppress the malignant phenotypes of BC cells, thereby restricting the development of BC.

Hypoxia-Induced TPM2 Methylation is Associated with Chemoresistance and Poor Prognosis in Breast Cancer.

BACKGROUND/AIMS: Tropomyosin-2 (TPM2) plays important roles in functions of the cytoskeleton, such as cytokinesis, vesicle transport, cell proliferation, migration and apoptosis,and these functions imply that TPM2 also plays a role in cancer development. Indeed, it has been shown that TPM2 plays a critical role in some cancers. However, the role of TPM2 in breast cancer is still poorly characterized. Thus, we explored the role of TPM2 in breast cancer. METHODS: We analysed TPM2 expression and its correlation with the clinicopathological features in breast cancer. Then, we examined the influence of hypoxia on TPM2 expression and methylation status using bisulfite sequencing PCR. Furthermore, we performed TPM2-mediated migration and invasion assays in the context of hypoxia and examined changes in matrix metalloproteinase-2 (MMP2) expression. Finally, we detected the influence of TPM2 on survival and chemotherapy drug sensitivity. RESULTS: We found that TPM2 expression is down-regulated in breast cancer cells compared to that in normal breast cells. The data from TCGA supported these results. Promoter methylation of TPM2, which could be induced by hypoxia, was responsible for its low expression. Hypoxia might regulate cell invasiveness partly by TPM2 down-regulation-mediated changes of MMP2 expression. Importantly, low TPM2 expression was correlated with lymph node metastasis (P=0.031), tumour node metastasis stage (P=0.01), histological grade (P=0.037), and shorter overall survival (P=0.028). Univariate and multivariate analyses indicated that TPM2 was an independent predictor in breast cancer patients. Paclitaxel chemotherapy did not benefit patients with low TPM2 expression (P<0.0001). TPM2 knockdown significantly reduced cell sensitivity to paclitaxel. CONCLUSION: TPM2 is a potential novel tumour suppressor gene in breast cancer. TPM2 is associated with poor survival and chemoresistance to paclitaxel in breast cancer, and TPM2 may represent a promising therapeutic gene target for breast cancer patients with chemoresistance.

Androgen Receptor Expression and Bicalutamide Antagonize Androgen Receptor Inhibit ß-Catenin Transcription Complex in Estrogen Receptor-Negative Breast Cancer.

BACKGROUND/AIMS: Little is known about the potential mechanism of action for androgen receptor (AR) targeting treatment in estrogen receptor (ER)-negative breast cancer. This study aimed to evaluate AR status and its prognosis in four breast cancer subtypes. Bicalutamide has been identified as an AR antagonist and used for treating AR+/ER- breast cancer in a phase II trial. Our studies will clarify its mechanism in breast cancer treatment. METHODS: A total of 510 consecutive cases of invasive ductal cancer (IDC) were evaluated in this study. The expression of AR was analyzed by immunohistochemistry and compared with patient survival, and its implications were evaluated in four subtypes of IDC. We examined bicalutamide as an AR antagonist to inhibit proliferation and increased apoptosis in AR+/ER- breast cancer cell lines. We explored the tumor suppressive functions of bicalutamide in vitro and vivo and its related mechanisms in AR+/ER- breast cancer. RESULTS: AR expression was related to that of ER (P<0.001), PR (P<0.001), Her2 (P=0.017), Ki-67(P=0.020) and to four subtypes (P<0.001). AR retained independent prognostic signifcance (P=0.007, ER- cases; P=0.001, ER+ cases; P=0.001, total cases). We found that bicalutamide significantly decreased viability and increased apoptosis in vitro and vivo. The mechanistic analysis revealed that bicalutamide blocked androgen-stimulated oncogenic AR and Wnt/ß-catenin signaling and inhibited the growth of AR+/ER- breast cancer. CONCLUSION: Our studies provide novel insights into bicalutamide as an antagonist of AR function in AR+/ER- breast cancer and reveal the mechanistic basis for targeting AR as a therapeutic opportunity for patients with AR+/ER- breast cancer.

Dysregulated expression of Slug, vimentin, and E-cadherin correlates with poor clinical outcome in patients with basal-like breast cancer.

BACKGROUND: Among the different types of breast cancer, basal-like breast cancer (BLBC) has an extremely poor prognosis due to its high rate of recurrence and metastasis. The present study aimed to investigate the correlation between the expression of Slug, E-cadherin, and vimentin, and the clinicopathological characteristics and prognosis of patients with BLBC. We further inferred from these findings whether Slug leads to a poor prognosis in patients with BLBC through epithelial-mesenchymal transition (EMT). METHODS: Immunohistochemistry was performed for 441 patients with breast cancer to determine the expression levels of Slug, E-cadherin, and vimentin. The correlation between protein expression and clinicopathological characteristics of patients with BLBC was evaluated, and these patients were followed up to determine survival rate. RESULTS: High Slug and low E-cadherin expression in BLBC patients closely correlated with histological grade, lymph node metastasis, tumor-node-metastasis (TNM) stage, and lymphatic vessel metastasis. Survival analysis revealed that the poor prognosis of BLBC is associated with TNM stage, high Slug and vimentin expression, and low E-cadherin levels. CONCLUSIONS: High Slug expression is closely correlated with poor prognosis in patients with BLBC. We speculate that this may be attributed to the involvement of Slug in the EMT of BLBC.

Correlation analysis between androgen receptor and the clinicopathological features and prognosis of mammary Paget's disease.

PURPOSE: Little is known about the prognostic value of androgen receptor (AR) status in mammary Paget's disease (MPD). The purpose of this study was to explore AR status and the distribution of molecular subtypes in MPD as well as the relationship between AR expression and clinicopathological factors and to evaluate its prognostic value. METHODS: We analyzed 170 MPD patients of varying subtypes. AR expression was verified by immunohistochemical staining, and the correlations between AR expression and clinicopathological characteristics and survival status were analyzed. We further investigated 91 MPD patients with invasive ductal carcinoma (MPD-IDC). RESULTS: AR was expressed in 55.3% of overall MPD patients, and 78.2% had the human epidermal growth factor receptor 2 (HER2) overexpression subtype. AR positivity was significantly correlated with BMI (P = 0.037) and pathological N stage (P = 0.023). Multivariate analysis indicated that pathological T stage and pathological N stage were independent prognostic factors for overall survival (OS). The positive AR group was significantly associated with better OS (P = 0.014). Among 91 MPD-IDC patients, AR was expressed in 56.0%, and 80.0% had the HER2 overexpression subtype. AR positivity was significantly correlated with pathological N stage (P = 0.033). Multivariate analysis indicated that AR and pathological T stage were independent prognostic factors for OS. Furthermore, AR positivity was significantly related to better OS (P = 0.005) in MPD-IDC patients as well as in patients with the HER2 overexpression subtype (P = 0.029). CONCLUSION: Our results confirmed that AR is a potential biomarker for evaluating the prognosis of patients.

Assessment of basal-like breast cancer by circulating tumor DNA analysis.

Standardized methods for the detection and assessment of circulating tumor DNA (ctDNA) in breast cancer are not sufficient. In the present study, the method and the potential application of ctDNA in the diagnosis of breast cancer were explored. DNA was extracted from the tumor tissues, plasma and peripheral blood cells of 11 patients with early-stage invasive breast cancer. Primers were designed against the exons of phosphatidylinositol-4,5-biphosphate 3-kinase catalytic subunit α, p53, epidermal growth factor receptor, Akt and phosphatase and tensin homolog. The amplicon-based method for whole-exon sequencing was performed. The associations between the ctDNA mutant frequency with the tumor DNA mutant frequency, and the ctDNA concentration with clinical data were analyzed. A linear association was identified between the concentration of ctDNA and the tumor volume for the 3 patients with basal-like breast cancer, and not in other subtypes. The mutation frequency differed the least between ctDNA and tissue DNA in basal-like breast cancer. ctDNA retained the constituent ratio of gene mutations identified in the corresponding tumor tissue. The ctDNA detection rate depended to a certain extent on the mutation frequency in tumor tissue; for example, a mutant locus with a mutation frequency of >30% in tissues presented a detection rate of >40% in plasma samples, whereas a locus with a mutation frequency of <10% in tissue was associated with a detection rate of ≤1% in the plasma. Therefore, ctDNA may reflect the mutations observed in cancer. Compared with other subtypes, ctDNA may be a more sensitive biomarker for the assessment of mutation and cancer burden in basal-like breast cancer relative to other subtypes.

Homeobox A11 hypermethylation indicates unfavorable prognosis in breast cancer.

Homeobox A11 (HOXA11) is one of the hypermethylated genes in breast cancer and its function in breast tumorigenesis remains elusive. In this study, we analyzed the methylation status of HOXA11 in 264 paired breast cancer and normal tissue as well as in matched serum samples by MethyLight assay. Further, the function of HOXA11 in breast tumorigenesis was analyzed by cell proliferation and migration assays. We found that HOXA11 was hypermethylated in cancer tissues (45.08%), especially in invasive ductal carcinomas (P<0.001), patients with a family history of cancer (P=0.033), cases with metastatic lymph nodes (P=0.004) and P53 positive group (P=0.017). Kaplan-Meier survival analysis and Cox regression analysis revealed that HOXA11 hypermethylation is an independent predictor of poor outcomes. The over expression of HOXA11 suppressed cell growth in MDA-MB-231, MCF7, SKBR3 and BT474 cells. In conclusion, the hypermethylation of HOXA11 is an independent prognostic biomarker in breast cancer. Additionally, HOXA11 can be a potential tumor suppressor.

A High-Quality Biobank Supports Breast Cancer Research in Harbin, China.

We established a standard breast cancer biobank at Harbin Medical University Cancer Hospital (HMUCH) in 2009. More than 100,000 biospecimens, including high-quality human breast cancer samples, matched blood samples, and adjacent normal tissues, were collected from patients and healthy donors in HMUCH and were then deposited in the repository. We reported the establishment of a biobank in our hospital and its crucial role in translational medicine research. We stored, processed, and distributed qualified biological specimens in accordance with international standard operating procedures. We also summarized the utilization of this biobank and its influence on research projects over the years since its establishment. Therefore, we can verify specific biomarkers that may aid in the development of targeted breast cancer therapies by using high-quality, well-annotated tissue samples provided by the biobank.

HOXD13 methylation status is a prognostic indicator in breast cancer.

Homeobox protein Hox-D13 is encoded by HOXD13 gene which is frequently methylated in cancer and has been recognized as a tumor suppressor in pancreatic cancer. In this study, we examined HOXD13 mRNA expression in 40 pairs of breast cancers and corresponding normal breast tissues. Bisulfite sequencing of HOXD13 promoter was performed in 6 pairs of breast tumors and corresponding normal breast tissues to examine the potential HOXD13 CpG methylated sites. HOXD13 DNA methylation frequency analysis was performed using MethyLight in 196 pairs of breast cancers and corresponding normal breast samples. DNA methylation status and clinico-pathological features were investigated. Kaplan-Meier survival analysis and Cox proportional hazards models were utilized to assess the effect of methylation status on overall survival. We found that 60% (24/40) of breast cancers showed low HOXD13 mRNA expression when compared with corresponding normal breast tissue. The predicted CpG island was located in the -1325 bp to +675 bp region. Next, the -332 bp site in HOXD13 gene promoter was further examined and in 57.7% (113/196) samples methylation was detected at this site. HOXD13 methylation was correlated with larger tumor size (P = 0.004), but not with other clinico-pathological parameters. In addition, patients with methylated -HOXD13 promoter had worse overall survival (OS) (P = 0.005). Based on our results we conclude that HOXD13 methylation is a common event in primary breast cancer and is associated with poor survival of breast cancer patients. HOXD13 methylation could therefore potentially be used as a prognostic factor for breast cancer.

Structural basis for specific recognition of single-stranded RNA by Toll-like receptor 13.

Toll-like receptors (TLRs) have crucial roles in innate immunity, functioning as pattern-recognition receptors. TLR13 recognizes a conserved sequence from bacterial 23S rRNA and then triggers an immune response. Here we report the crystal structure of the mouse TLR13 ectodomain bound by a 13-nt single-stranded (ss) RNA derived from 23S rRNA. The ssRNA induces TLR13 dimerization but assumes a stem-loop-like structure that is completely different from that in the bacterial ribosome but nevertheless is crucial for TLR13 recognition. Most of the RNA nucleotides are splayed out to make base-specific contacts with the concave surface of TLR13, and RNA-specific interactions are important to allow TLR13 to distinguish RNA from DNA. Interestingly, a viral-derived 16-nt ssRNA predicted to form a similar stem-loop-like structure also induces TLR13 activation. Together, our results reveal the structural mechanism of TLR13's sequence- and conformation-specific recognition of ssRNA.

Promoter hypermethylation of ARID1A gene is responsible for its low mRNA expression in many invasive breast cancers.

ARID1A (AT-rich interactive domain 1A) has recently been identified as a tumor suppressor gene. Its mRNA expression is significantly low in many breast cancers; this is often associated with more aggressive phenotypes. However, the underlying molecular mechanism for its low expression has not been fully understood. This study was undertaken to evaluate the contribution of gene copy number variation, mutations, promoter methylation and histone modification to ARID1A's low expression. 38 pairs of breast invasive ductal carcinomas and their normal breast tissue counterparts from the same patients were randomly selected for gene expression and copy number variation detection. Promoter methylation and histone modification levels were evaluated by MeDIP-qPCR and ChIP-qPCR, respectively. PCR product Sanger sequencing was carried out to detect the exon mutation rate. Twenty-two out of 38 invasive ductal carcinomas in the study (57.9%) revealed ARID1A mRNA low expression by realtime RT-PCR. The relative promoter methylation level was, significantly higher in ARID1A mRNA low expression group compared with its high expression group (p<0.001). In the low expression group, nineteen out of 22 invasive ductal carcinomas (86.4%) exhibited ARID1A promoter hypermthylation. In addition, the promoter hypermethylation was accompanied with repressive histone modification (H3K27Me3). Although five out of 38 invasive ductal carcinomas (13.2%) exhibited loss of ARID1A gene copy number by realtime PCR and nine exon novel mutations are seen from eight out of 33 invasive ductal carcinomas (24.2%), there was no statistically significant difference in both ARID1A mRNA low and high expression groups (p=0.25,and p=0.68, respectively). We demonstrate that promoter hypermethylation was the main culprit for ARID1A mRNA low expression in invasive ductal carcinomas. The influence of mutation and copy number variation on the expression were statistically insignificant at mRNA level, and were, therefore, not considered the main causes for ARID1A mRNA low expression in invasive breast cancer.

Long CAG repeat sequence and protein expression of androgen receptor considered as prognostic indicators in male breast carcinoma.

BACKGROUND: The androgen receptor (AR) expression and the CAG repeat length within the AR gene appear to be involved in the carcinogenesis of male breast carcinoma (MBC). Although phenotypic differences have been observed between MBC and normal control group in AR gene, there is lack of correlation analysis between AR expression and CAG repeat length in MBC. The purpose of the study was to investigate the prognostic value of CAG repeat lengths and AR protein expression. METHODS: 81 tumor tissues were used for immunostaining for AR expression and CAG repeat length determination and 80 normal controls were analyzed with CAG repeat length in AR gene. The CAG repeat length and AR expression were analyzed in relation to clinicopathological factors and prognostic indicators. RESULTS: AR gene in many MBCs has long CAG repeat sequence compared with that in control group (P = 0.001) and controls are more likely to exhibit short CAG repeat sequence than MBCs. There was statistically significant difference in long CAG repeat sequence between AR status for MBC patients (P = 0.004). The presence of long CAG repeat sequence and AR-positive expression were associated with shorter survival of MBC patients (CAG repeat: P = 0.050 for 5y-OS; P = 0.035 for 5y-DFS AR status: P = 0.048 for 5y-OS; P = 0.029 for 5y-DFS, respectively). CONCLUSION: The CAG repeat length within the AR gene might be one useful molecular biomarker to identify males at increased risk of breast cancer development. The presence of long CAG repeat sequence and AR protein expression were in relation to survival of MBC patients. The CAG repeat length and AR expression were two independent prognostic indicators in MBC patients.