Downregulation of RASSF6 promotes breast cancer growth and chemoresistance through regulation of Hippo signaling.

This study aims to investigate the clinical significance and biological function of RASSF6 in human breast cancers. RASSF6 protein was found to be downregulated in 42 of 95 human breast cancer tissues by immunohistochemistry, which was associated with advanced TNM stage and nodal metastasis. The rate of RASSF6 downregulation was higher in Triple-negative breast cancer (TNBC). Downregulation of RASSF6 protein was also found in breast cancer cell lines, especially in TNBC cell lines. Overexpression RASSF6 inhibited cell growth rate and colony formation ability in MDA-MB-231 cell line. Depletion of RASSF6 promoted proliferation rate and colony formation ability in T47D cell line. Flow cytometry/PI staining demonstrated that RASSF6 inhibited cell cycle transition. AnnxinV/PI analysis showed that RASSF6 overexpression upregulated apoptosis induced by cisplatin (CDDP) while RASSF6 depletion inhibited apoptosis. JC-1 staining showed that RASSF6 overexpression inhibited mitochondrial membrane potential. Western blot analysis demonstrated that RASSF6 repressed cyclin D1, YAP while upregulated p21, cleaved caspase 3 and cytochrome c expression. In addition, RASSF6 activated Hippo signaling pathway by upregulating MST1/2 and LATS1 phosphorylation. Restoration of YAP inhibited cleaved caspase 3 and cytochrome c which were induced by RASSF6. Restoration of YAP also reduced the rate of CDDP induced apoptosis. In conclusion, this study provided evidence that RASSF6 functions as a potential tumor suppressor in human breast cancer through activation of Hippo pathway.

Prognostic significance of body mass index in breast cancer patients with hormone receptor-positive tumours after curative surgery.

PURPOSE: Obesity has been recognized as a significant risk factor for postmenopausal breast cancer. The aim of this study is to investigate the prognostic significance of body mass index (BMI) in hormone receptor-positive, operable breast cancer. METHODS: In this retrospective cohort study, 1,192 consecutive patients with curative resection of primary breast cancer were enrolled. Patients were assigned to two groups according to BMI: normal or underweight (BMI < 23.0 kg/m²) and overweight or obese (BMI ≥ 23.0 kg/m²). Associations among BMI and clinicopathological characteristics and prognosis of patients were assessed. RESULTS: A high BMI was significantly (P < 0.01) correlated with age, nodal stage, ALNR, ER positivity, PR positivity and menopausal status at diagnosis. Univariate analysis revealed that BMI, pathologic T stage, nodal stage, axillary lymph node ratio (ALNR) and adjuvant radiotherapy history were significantly (P < 0.05) associated with disease-free survival and overall survival, irrespective of tumour hormone receptor status. Multivariate analysis revealed BMI as an independent prognostic factor in all cases and in hormone receptor-positive cases. CONCLUSION: A high BMI (≥ 23.0 kg/m²) is independently associated with poor prognosis in hormone receptor-positive breast cancer.

[Influence of the number of removed axillary lymph nodes on the prognosis of node-negative primary breast cancer].

OBJECTIVE: To analyze the relationship between the number of removed axillary lymph nodes and prognosis of axillary node-negative breast cancer. METHODS: The clinicopathological data of 655 patients with breast cancer were analyzed retrospectively. The disease-free survival curves were generated according to the number of removed axillary lymph nodes using Kaplan-Meier plots. The correlation between the co-variables and rate of breast cancer-related events was analyzed using Cox model. RESULTS: The overall five year-disease free survival rate of the 655 cases was 94.4%. The rate of patients with lymph node number ≤ 12 was 90.3%, and that of lymph node number > 12 was 96.5%, with a statistically significant difference (P = 0.009). Significantly less breast cancer-related events were observed in patients with lymph node number > 12 (15/426, 3.5%) than that in patients with lymph node number ≤ 12 (22/229, 9.6%) (P = 0.009). CONCLUSIONS: When axillary node dissection is indicated, dissection of lymph nodes >12 leads to much less breast cancer-related events than that in patients with dissected lymph node ≤ 12. The more lymph nodes are dissected, the more accurate prognosis can be estimated.

Cancer-associated adipocytes release FUCA2 to promote aggressiveness in TNBC.

Cancer-associated adipocytes (CAAs) have been suggested to promote tumor progression. Yet, the role of CAAs in triple-negative breast cancer (TNBC) is poorly investigated. We compared the expression of secretory protein-encoding genes in CAAs and control adipocytes. The effect of key secretory protein(s) on TNBC cell behaviors was explored. CAAs expressed and secreted FUCA2 at greater levels than control adipocytes. When FUCA2 activity was blocked with a neutralizing antibody, TNBC cell proliferation and migration induced by CAA-conditioned medium was impaired. In contrast, supplement of exogenous FUCA2 protein reinforced the proliferation, colony formation, and migration of TNBC cells. In vivo studies confirmed that FUCA2 exposure enhanced tumorigenesis and metastasis of TNBC cells. Mechanistic investigation revealed that FUCA2 induced TNBC aggressiveness through TM9SF3-dependent signaling. Depletion of TM9SF3 blocked CAA- and FUCA2-induced TNBC cell proliferation and migration. Compared to adjacent breast tissues, TNBC tissues had increased expression of TM9SF3. Moreover, high TM9SF3 expression was associated with advanced TNM stage, lymph node metastasis, and shorter overall survival of TNBC patients. Altogether, CAAs secrete FUCA2 to promote TNBC growth and metastasis through interaction with TM9SF3. Inhibition of TM9SF3 may represent a potential therapeutic strategy in the treatment of TNBC.

Fascin, an actin-bundling protein, promotes breast cancer progression in vitro.

Fascin, an actin-cross-linking protein, is up-regulated in breast cancer and correlates with a more aggressive disease. This study was conducted to elucidate the effects of manipulating fascin in breast cancer cells on the metastasis-associated events, including proliferation, adhesion, invasion, epithelial-mesenchymal transition (EMT) and enrichment of a CD44(+) /CD24(-) subpopulation that show some stem/progenitor cell properties. Western blot analysis of a panel of breast cancer cell lines revealed high expression of fascin in MDA-MB-435 and MDA-MB-231 cells but revealed no or low expression in MDA-MB-453, Her-18 and T47D. Gain-of-function and loss-of-function studies in breast cancer cells demonstrated that forced expression of fascin promoted cell proliferation assessed by the MTT assay, decreased cellular adhesion to fibronectin and potentiated the invasive capacity in the Transwell chamber invasion assay. Conversely, down-regulation of fascin via small interfering RNA increased cell adhesion and facilitated cell proliferation and invasion. In addition, fascin participated in the EMT and modulated the proportion of the CD44(+) /CD24(-) subpopulation in breast cancer cells. In conclusion, our data highlight an important role for fascin in breast cancer progression in vitro through orchestrating a variety of cellular events associated with metastasis, and thus, targeting this gene might have therapeutic implications.

Long Non-coding RNA LOXL1-AS1 Drives Breast Cancer Invasion and Metastasis by Antagonizing miR-708-5p Expression and Activity.

LOXL1-AS1, a recently characterized long non-coding RNA (lncRNA), has been reported to modulate tumor progression in several types of cancer. However, the expression and role of LOXL1-AS1 in breast cancer remain unclear. In this study, we sought to identify novel lncRNA regulators engaged in breast cancer metastasis. To this end, we examined 42 cancer-related lncRNAs between MCF7 (with low metastatic potential) and MDA-MB-231 (with high metastatic potential) cells. These lncRNAs have been found to affect the invasiveness of several cancer types, but they are still undefined in breast cancer. Among the 42 candidates, LOXL1-AS1 is significantly increased in MDA-MB-231 cells relative to MCF7 cells. We also show that LOXL1-AS1 is upregulated in breast cancer tissues and cells compared to noncancerous counterparts. Increased LOXL1-AS1 expression is correlated with tumor stage and lymph node metastasis in breast cancer patients. Biologically, overexpression of LOXL1-AS1 enhances and knockdown of LOXL1-AS1 suppresses breast cancer cell migration and invasion. In vivo studies demonstrate that depletion of LOXL1-AS1 inhibits breast cancer metastasis. Mechanistically, LOXL1-AS1 sponges miR-708-5p to increase nuclear factor κB (NF-κB) activity. LOXL1-AS1 can also interact with EZH2 protein to enhance EZH2-mediated transcriptional repression of miR-708-5p. Rescue experiments indicate that co-expression of miR-708-5p attenuates LOXL1-AS1-induced invasiveness in breast cancer. In addition, there is a negative correlation between LOXL1-AS1 and miR-708-5p expression in breast cancer specimens. Overall, LOXL1-AS1 upregulation facilitates breast cancer invasion and metastasis by blocking miR-708-5p expression and activity. LOXL1-AS1 serves as a potential therapeutic target for breast cancer treatment.

Dietary isoflavones or isoflavone-rich food intake and breast cancer risk: A meta-analysis of prospective cohort studies.

BACKGROUND & AIMS: Previous studies implied that dietary isoflavone intake may reduce the risk of developing breast cancer, but some have shown ambiguous results. This study aimed to systematically evaluate and summarize available evidence on the effect dietary isoflavone intake has on the risk of developing breast cancer. METHODS: PubMed, Embase, and the Cochrane Library were searched for prospective cohort studies published through April 2017 that evaluated the effect of dietary isoflavone intake on the development of breast cancer. RESULTS: Sixteen prospective cohort studies, involving 11,169 breast cancer cases and 648,913 participants, were identified and included in our data analysis. The pooled relative risk (RR) of breast cancer was 0.99 for high versus low intake of isoflavones (95% confidence interval [CI], 0.91-1.09; P = 0.876) and 0.99 for moderate versus low intake of isoflavones (95%CI, 0.92-1.05; P = 0.653), with insignificant heterogeneity (P = 0.187 for high versus low, and P = 0.192 for moderate versus low). While a moderate consumption of soy-based foods did not significantly affect breast cancer risk, a high intake of soy-based foods associated with a lower risk of developing breast cancer. Considering specific foods, an increased the risk of developing breast cancer was seen with a moderate intake of formononetin, but no significant associations were found between breast cancer risk and other isoflavone-rich diets. CONCLUSIONS: The present meta-analysis indicates that women with a high dietary intake of soy foods may experience a statistically significant reduction in breast cancer risk. However, moderate formononetin consumption may increase the risk of developing breast cancer.

TRIM32 promotes proliferation and confers chemoresistance to breast cancer cells through activation of the NF-κB pathway.

Dysregulation of TRIM32 has been implicated in several human cancers, however, its clinical significance and biological function in breast cancer have not been investigated. Using immunohistochemistry, we found that TRIM32 expression is upregulated in breast cancer tissues and that it correlates with advanced stage and poor prognosis. TRIM32 is also overexpressed in 4/7 breast cancer cell lines. CCK8 and colony formation assays showed that TRIM32 depletion inhibited proliferation and colony formation in the T47D cell line, while TRIM32 overexpression promoted MCF-7 cell growth and colony formation. Cell viability and Annexin V/PI staining demonstrated that TRIM32 maintained breast cancer cell survival and reduced apoptosis rate when cells were treated with cisplatin. Western blot analysis demonstrated that TRIM32 overexpression resulted in an upregulation of p-IκB, p-p65, cIAP1, and cIAP2 and a downregulation of p21 and p27 in MCF-7 cells. TRIM32 depletion in T47D cells demonstrated the opposite results, suggesting that TRIM32 may activate the NF-κB pathway. The NF-κB inhibitor BAY 11-7082 blocked the effects of TRIM32 on cisplatin resistance and cIAP1/2 protein regulation. Taken together, the present study demonstrates that TRIM32 downregulates p21/p27 and upregulates IAP family proteins to facilitate breast cancer cell growth and inhibit drug-induced apoptosis, possibly through the NF-κB signaling pathway.

Clinical and biological significance of hepsin overexpression in breast cancer.

OBJECTIVE: Although many studies have documented the tumor-promoting role of hepsin in several types of malignancies, little is known about its clinical and biological significance in breast cancer. MATERIALS AND METHODS: Hepsin expression was examined in 4 pairs of fresh breast tumor samples and corresponding nontumor breast tissues by Western blotting. Immunohistochemistry for hepsin was performed on an additional cohort of 215 archival breast cancer samples. The clinical significance of hepsin expression was analyzed. Knockdown of hepsin expression was performed in 2 breast cancer cell lines, MDA-MB-231 and HER18, with a high abundance of endogenous hepsin, and the effects of hepsin silencing on cell invasion and proliferation were evaluated. RESULTS: Hepsin was aberrantly overexpressed in breast cancer tissues relative to adjacent nontumor tissues. Its overexpression was significantly associated with tumor stage (P = 0.037), lymph node metastasis (P = 0.010), estrogen receptor positivity (P = 0.019), and progesterone receptor positivity (P < 0.0001) in patients with breast cancer. Down-regulation of hepsin expression by small interfering RNA (siRNA) significantly reduced cell proliferation and invasion in both the MDA-MB-231 and HER18 cells compared to nonspecific control small interference RNA. CONCLUSION: Our data demonstrate that hepsin expression is frequently up-regulated in breast cancer tissues, which is associated with tumor growth and progression. Thus, inhibition of hepsin expression might be of therapeutic significance.

Expression of CD133, PAX2, ESA, and GPR30 in invasive ductal breast carcinomas.

BACKGROUND: Biomarkers in breast neoplasms provide invaluable information regarding prognosis and help determining the optimal treatment. We have examined the possible correlation between cancer stem cell (CSC)-like markers (CD133, paired box gene 2 protein (PAX2), epithelial specific antigen (ESA)), and a new membrane estrogen receptor (G-protein coupled receptor 30 (GPR30)) in invasive ductal breast carcinomas with known clinicopathological parameters, tumor recurrence, and expression of some known biomarkers. METHODS: In 74 invasive ductal breast carcinomas, we investigated the protein expression of these molecular markers by immunohistochemistry, and their associations with known clinicopathological parameters, tumor recurrence, and expression of some known biomarkers. We studied the interrelationship between the expressions of these proteins. RESULTS: CD133, a putative CSC marker, was positively related to tumor size, tumor stage, and lymph node metastasis. PAX2 was negatively correlated with tumor recurrence. ESA, one of the breast CSC markers, was an indicator of tumor recurrence. GPR30 was associated with hormone receptors. Despite the correlation between GPR30 and the nuclear estrogen receptor, the expression was dependent. Positive staining of GPR30 in tumors displayed a significant association with high C-erbB2 expression and a tendency for tumor recurrence. A positive relationship between GPR30 and CD133 existed. CONCLUSION: Detecting the expression of CD133, PAX2, ESA, and GPR30 in invasive ductal breast carcinomas may be of help in more accurately predicting the aggressive properties of breast cancer and determining the optimal treatment.