LncRNA POU3F3 promotes proliferation and inhibits apoptosis of cancer cells in triple-negative breast cancer by inactivating caspase 9

It has been reported that lncRNA POU3F3 was upregulated in esophageal squamous-cell carcinomas, indicating its role as an oncogene in this disease. However, the mechanism of its function and its involvement in other malignancies is unknown. In the present study we found that expression levels of lncRNA POU3F3 were higher in tumor tissues than in adjacent healthy tissues of triple negative breast cancer (TNBC) patients and were significantly and inversely correlated with levels of cleaved caspase 9 only in tumor tissues. In addition, plasma levels of lncRNA POU3F3 were higher in TNBC patients than in healthy controls and were significantly and inversely correlated with levels of cleaved caspase 9 only in TNBC patients. In addition, treatment of exogenous Cleaved Caspase-9 significantly attenuated the effects of lncRNA POU3F3 overexpression on cancer cell proliferation and apoptosis. lncRNA POU3F3 may promote proliferation and inhibit apoptosis of cancer cells in triple-negative breast cancer.     

Up-Regulation of RFC3 Promotes Triple Negative Breast Cancer Metastasis and is Associated With Poor Prognosis Via EMT

Triple-negative breast cancer (TNBC) was regarded as the most aggressive and mortal subtype of breast cancer (BC) since the molecular subtype system has been established. Abundant studies have revealed that epithelial-mesenchymal transition (EMT) played a pivotal role during breast cancer metastasis and progression, especially in TNBC. Herein, we showed that inhibition the expression of replication factor C subunit 3 (RFC3) significantly attenuated TNBC metastasis and progression, which was associated with EMT signal pathway. In TNBC cells, knockdown of RFC3 can down-regulate mesenchymal markers and up-regulate epithelial markers, significantly attenuated cell proliferation, migration and invasion. Additionally, silencing RFC3 expression can decrease nude mice tumor volume, weight and relieve lung metastasis in vivo. Furthermore, we also demonstrated that overexpression of RFC3 in TNBC showed increased metastasis, progression and poor prognosis. We confirmed all of these results by immunohistochemistry analysis in 127 human TNBC tissues and found that RFC3 expression was significantly associated with poor prognosis in TNBC. Taken all these findings into consideration, we can conclude that up-regulation of RFC3 promotes TNBC progression through EMT signal pathway. Therefore, RFC3 could be an independent prognostic factor and therapeutic target for TNBC.     

LIN9 confers paclitaxel resistance in triple negative breast cancer cells by upregulating CCSAP

LIN9 functions to regulate cell mitotic process.Dysregulation of LIN9 expression is associated with development of human cancers.In this study we assessed the association of LIN9 expression with paclitaxel resistance and clarified the underlying mechanisms for the first time.LIN9 expression in breast cancer tissues was retrieved from publicly available online databases and statistically analyzed.Human TNBC cell lines MDA-MB-231 and MDA-MB-468 and their corresponding paclitaxelresistant sublines 231PTX and 468PTX were used to assess the expression of LIN9 by qRT-PCR and Western blot,cell growth by cell counting,cell viability by MTS assay,and cell apoptosis by flow cytometry.The data showed that high LIN9 expression in breast cancer patients receiving chemotherapy was related to poor overall survival (OS).LIN9 expression was upregulated in paclitaxel-resistant TNBC cells compared to their parental cells.Knockdown of LIN9 or treatment of paclitaxel-resistant TNBC cells with a bromo-and extra-terminal domain inhibitor (BETi) JQ1 which also decreased LIN9 expression enhanced the sensitivity of paclitaxel-resistant TNBC cells to paclitaxel.Mechanistically,decreased LIN9 in resistant cell lines reduced tumor cell viability,promoted multinucleated cells formation and induced tumor cell apoptosis,potentially by directly regulating microtubule-binding protein CCSAP.In conclusion,high LIN9 expression contributed to poor clinical outcomes and paclitaxel resistance in TNBC and BETi,targeting LIN9 expression,could be a reversible drug for PTX-resistant TNBC patients.     

Triple negative breast cancer: microRNA expression profile and novel discriminators according to BRCA1 status

Triple-negative breast cancer (TNBC) represents 15% of breast carcinomas. More than 80% of women with a breast cancer associated with a breast cancer type 1 (BRCA1) mutation develop a TNBC. microRNAs (miRNAs) play critical roles in diverse biological processes and are aberrantly expressed in several human neoplasms including breast cancer, where they function as actors of tumor onset, behavior, and progression. However, an extensive microRNA profile has not yet been determined for TNBC. Taqman low-density arrays (TLDAs) were used to screen the expression level of 667 miRNAs in TNBC versus normal breast tissues. Our TLDA results revealed 20 differentially expressed miRNAs among which 14 (10 upregulated and four downregulated) were confirmed by an individual quantitative real-time polymerase chain reaction. Interestingly, a novel link between BRCA1 status and miRNA expression level was identified through miR-96 and miR-10b that were very important discriminators between TNBC with mutated BRCA1 and TNBC with wild type BRCA1. This study promises discoveries of new pathological pathways at work in this dreadful disease and clearly warrants validation in large prospective studies with the aim of identifying novel biomarkers for diagnosis and targets for clinical interventions.     

Inhibiting β-catenin disables nucleolar functions in triple-negative breast cancer

Triple-negative breast cancer (TNBC) patients with upregulated Wnt/β-catenin signaling often have poor clinical prognoses. During pathological examinations of breast cancer sections stained for β-catenin, we made the serendipitous observation that relative to non-TNBC, specimens from TNBC patients have a greater abundance of nucleoli. There was a remarkable direct relationship between nuclear β-catenin and greater numbers of nucleoli in TNBC tissues. These surprising observations spurred our investigations to decipher the differential functional relevance of the nucleolus in TNBC versus non-TNBC cells. Comparative nucleolar proteomics revealed that the majority of the nucleolar proteins in TNBC cells were potential targets of β-catenin signaling. Next, we undertook an analysis of the nucleolar proteome in TNBC cells in response to β-catenin inhibition. This effort revealed that a vital component of pre-rRNA processing, LAS1 like ribosome biogenesis factor (LAS1L) was significantly decreased in the nucleoli of β-catenin inhibited TNBC cells. Here we demonstrate that LAS1L protein expression is significantly elevated in TNBC patients, and it functionally is important for mammary tumor growth in xenograft models and enables invasive attributes. Our observations highlight a novel function for β-catenin in orchestrating nucleolar activity in TNBCs.Subject terms: Breast cancer, Organelles, Breast cancer, Metastasis     

UV radiation resistance-associated gene (UVRAG) promotes cell proliferation,migration, invasion by regulating cyclin-dependent kinases (CDK) and integrin-β/Src signaling in breast cancer cells

Breast cancer is a highly heterogeneous group of human cancer with distinct genetic, biological and clinicopathological features. Triple-negative breast cancer (TNBC) is the most aggressive and metastatic type of breast cancer and associated with poor patient survival. However, the role of UV Radiation Resistance-Associated Gene (UVRAG) in TNBC remains unknown. Here, we report that UVRAG is highly upregulated in all TNBC cells and its knockdown leads to the inhibition of cell proliferation, colony formation and progression of cell cycle, which is associated with and reduced expression of cell cycle related protein expression, including Cyclin A2, B1, D1, cdc2 and cdk6 in TNBC cells. Inhibition of UVRAG also suppressed cell motility, migration and invasion of TNBC cells by inhibition of Integrin β1 and β3 and Src activity. Our findings suggest for the first time that UVRAG expression contributes to proliferation, cell cycle progression, motility/migration and invasion of TNBC cells. Thus, targeting UVRAG could be a potential strategy in breast cancer especially against TNBC.

     

Characterization of MTAP Gene Expression in Breast Cancer Patients and Cell Lines

MTAP is a ubiquitously expressed gene important for adenine and methionine salvage. The gene is located at 9p21, a chromosome region often deleted in breast carcinomas, similar to CDKN2A, a recognized tumor suppressor gene. Several research groups have shown that MTAP acts as a tumor suppressor, and some therapeutic approaches were proposed based on a tumors´ MTAP status. We analyzed MTAP and CDKN2A gene (RT-qPCR) and protein (western-blotting) expression in seven breast cancer cell lines and evaluated their promoter methylation patterns to better characterize the contribution of these genes to breast cancer. Cytotoxicity assays with inhibitors of de novo adenine synthesis (5-FU, AZA and MTX) after MTAP gene knockdown showed an increased sensitivity, mainly to 5-FU. MTAP expression was also evaluated in two groups of samples from breast cancer patients, fresh tumors and paired normal breast tissue, and from formalin-fixed paraffin embedded (FFPE) core breast cancer samples diagnosed as Luminal-A tumors and triple negative breast tumors (TNBC). The difference of MTAP expression between fresh tumors and normal tissues was not statistically significant. However, MTAP expression was significantly higher in Luminal-A breast tumors than in TNBC, suggesting the lack of expression in more aggressive breast tumors and the possibility of using the new approaches based on MTAP status in TNBC.     

The malignant potential of HIV-associated Kaposi sarcoma

Background

Breast cancer is the most common cancer and cause of deaths in women around the world. Oncogene amplification usually occurs late in tumor progression and correlates well with aggressiveness of tumor. In fact the function of the S100A4 protein and its role in metastasis is unclear at present. The purpose of the study was to determine the expression of S100A4 protein in the invasion status and metastatic potential of breast cancer by using tissue microarray and to determine its role in breast cancer based on the expression of S100A4 gene product.

Methods

S100A4 protein expression was examined by immunohistochemistry (IHC) using commercially available tissue microarray containing malignant and normal breast tissue cores from 216 patients.

Results

S100A4 was absent in normal breast tissues while positive in 45.1% of infiltrating ductal carcinoma (IDC) node negative and 48.8% of infiltrating lobular carcinoma node negative. In paired samples, S100A4 protein was expressed in 13.5% of IDC node positive cases and 35.1% of matched lymph node metastasis.

Conclusion

S100A4 protein expression appears widely expressed in early and advanced breast cancer stages compared with normal breast. Our study suggests S100A4 may play a role in breast cancer progression and may prove to be an independent marker of breast cancer which appears to be down regulated in more advanced stages of breast cancer.     

HIF1A-AS2 predicts poor prognosis and regulates cell migration and invasion in triple-negative breast cancer

The aberrant expression of hypoxia-inducible factor 1 alpha (HIF1A)-antisense RNA 2 (HIF1A-AS2) was found in various human cancers including breast cancer. The aim of this study was to present more evidence about the role HIF1A-AS2 on triple-negative breast cancer (TNBC). In our results, HIF1A-AS2 was also found to be upregulated in TNBC tissues compared with non-TNBC tissues or adjacent normal tissues. Besides, HIF1A-AS2 expression was also elevated in TNBC cell lines compared with the normal breast epithelial cell line. Moreover, high expression of HIF1A-AS2 was associated with lymph node metastasis, distant metastasis and unfavorable histological grade in TNBC patients. Survival analysis showed a TNBC patient with high HIF1A-AS2 expression had shorter overall survival than patients with low HIF1A-AS2 expression, and HIF1A-AS2 high expression acted as an independent poor prognostic factor for overall survival in TNBC patients. The cell migration and invasion assays suggested inhibition of HIF1A-AS2 obviously depressed TNBC cell migration and invasion. In conclusion, HIF1A-AS2 serves as a novel biomarker for predicting clinical progression and prognosis in TNBC.     

SENP1 promotes triple-negative breast cancer invasion and metastasis via enhancing CSN5 transcription mediated by GATA1 deSUMOylation

TNBC is characterized by high incidence of visceral metastasis and lacks effective clinical targets. This study aims to delineate the molecular mechanisms of SENP1 in TNBC invasion and metastasis. By using IHC to test the SENP1 expression in TNBC tissues, we analyzed the relationship between SENP1 expression and TNBC prognosis. We showed that SENP1 expression was higher in TNBC tumor tissues and related to TNBC prognosis, supporting SENP1 as an independent risk factor. High expression of SENP1 was significantly associated with histologic grade and tumor lymph node invasion. Intriguingly, the expression levels of SENP1 in TNBC tumors were significantly correlated with that of CSN5, GATA1 and ZEB1. Importantly, SENP1 promoted TNBC cell migration and invasion by regulating ZEB1 deubiquitination and expression through CSN5. Further studies showed that deSUMOylation at lysine residue K137 of GATA1 enhanced the binding of GATA1 to the CSN5 promoter and transactivated CSN5 expression. In addition, we showed that ZEB1 is deubiquitinated at lysine residue K1108. Our in vivo studies also indicated that reduction in SENP1 expression upregulated GATA1 SUMOylation, and thus resulted in decreased expression of CSN5 and ZEB1 in the tumor microenvironment, which decelerated TNBC progression and metastasis. SENP1 promoted CSN5-mediated ZEB1 protein degradation via deSUMOylation of GATA1, and thus influenced TNBC progression. These findings suggest that SENP1 could be utilized as a potential target for blockade of TNBC development and thus provide a totally new approach for TNBC treatment.     

Lamin B2 promotes the progression of triple negative breast cancer via mediating cell proliferation and apoptosis

Triple negative breast cancer (TNBC) is a more common type of breast cancer with high distant metastasis and poor prognosis. The potential role of lamins in cancer progression has been widely revealed. However, the function of lamin B2 (LMNB2) in TNBC progression is still unclear. The present study aimed to investigate the role of LMNB2 in TNBC. The cancer genome atlas (TCGA) database analysis and immunohistochemistry (IHC) were performed to examine LMNB2 expression levels. LMNB2 short hairpin RNA plasmid or lentivirus was used to deplete the expression of LMNB2 in human TNBC cell lines including MDA-MB-468 and MDA-MB-231. Alterations in cell proliferation and apoptosis in vitro and the nude mouse tumorigenicity assay in vivo were subsequently analyzed. The human TNBC tissues shown high expression of LMNB2 according to the bioinformation analysis and IHC assays. LMNB2 expression was correlated with the clinical pathological features of TNBC patients, including pTNM stage and lymph node metastasis. Through in vitro and in vivo assays, we confirmed LMNB2 depletion suppressed the proliferation and induced the apoptosis of TNBC cells, and inhibited tumor growth of TNBC cells in mice, with the decrease in Ki67 expression or the increase in caspase-3 expression. In conclusion, LMNB2 may promote TNBC progression and could serve as a potential therapeutic target for TNBC treatment.     

Synergistic anticancer action of quercetin and curcumin against triple-negative breast cancer cell lines

Women with the breast cancer type 1 susceptibility protein (BRCA1) mutation and loss of BRCA1 expression are reported to have an increased risk of triple-negative breast cancer (TNBC). Targeting BRCA1 modulation might offer a therapeutic option to treat TNBC patients. Our studies detected that BRCA1 is poorly expressed in TNBC cell lines and highly expressed in ER⁺ breast cancer cell lines. To modulate BRCA1 expression, we tested two different dietary components to find out if any would induce tumor suppressor genes. We detected that quercetin and curcumin dose-dependently enhanced the BRCA1 expression. Further, a synergistic action of quercetin and curcumin was observed in modulating the BRCA1 level and in inhibiting the cell survival and migration of TNBC cell lines. Quercetin and curcumin appeared to induce BRCA1 promoter histone acetylation. Furthermore, BRCA1 knockdown induced cell survival and cell migration in ER ⁺ cells were significantly decreased by the combined treatment of quercetin and curcumin. Our present study concluded that the combination treatment of quercetin and curcumin acts synergistically to induce anticancer activity against TNBC cells by modulating tumor suppressor genes.