MicroRNA-199a-3p promotes drug sensitivity in triple negative breast cancer by down-regulation of BRCA1.

MiR-199a-3p was previously predicted to target tumor suppressor gene BRCA1, which has been linked to cancer onset and therapeutic response. In this study, the effects of miR-199a-3p-mediated BRCA1 dysfunction on triple-negative breast cancer (TNBC) progression and chemosensitivity were assessed. The association between miR-199a-3p and BRCA1 expression was examined in TNBC tumors and verified with luciferase reporter and protein assays. Tumorigenic functions of miR-199a-3p in TNBC cells were investigated by cell proliferation, clonogenic and migration assays. The sensitivities to chemotherapeutic drugs were tested with cisplatin and PARP inhibitor (veliparib) treatments. Mouse xenograft model was used to examine the effects of miR-199a-3p on tumor growth and drug response in vivo. MiR-199a-3p was shown to directly target BRCA1 in TNBC cells, resulting its downregulation and reduced luciferase reporter activity mediated by BRCA1 3'-UTR. Ectopic miR-199a-3p in TNBC cells exerted inhibitory effects on cell proliferation, migration and xenograft tumor growth. Moreover, miR-199a-3p was shown to reverse cisplatin-resistance and sensitize TNBC cells to veliparib, which might be due to repressed DNA repair ability and induced cell apoptosis. Our results demonstrated the tumor suppressive effects of miR-199a-3p on TNBC and induction on chemotherapeutic sensitivities, which were correlated with BRCA1 gene dysfunction. These findings may provide insights into the potential prognostic and therapeutic values of miR-199a-3p in patients with TNBC.

Human haptoglobin contributes to breast cancer oncogenesis through glycolytic activity modulation.

Cellular metabolism reprogramming is a hallmark in cancers including breast cancer. Switching off the glycolytic energy in cancer has been indicated as one of the anti-cancer strategies. Aberrant haptoglobin (HP) expression has been shown to cause metabolic dysfunction and implicated in different malignancies. However, its roles in breast cancer and glycolysis remain elusive. Here, we reported HP was upregulated in breast cancer tissues and the circulation. HP conferred oncogenic roles by regulating cell cycle progression and apoptosis in breast cancer cells. Further analysis identified the correlation between HP and glycolytic enzymes such as glucose-6-phosphate isomerase (GPI) and hexokinase (HK). Glycolytic activities were altered upon HP knockdown which were confirmed by glucose uptake and LDH activity assays. GPI was found to be downstream effector of HP while knockdown of GPI led to decreased glycolytic activity and restored oxygen consumption. GPI silencing decreased cell migration/invasion ability and sensitized breast cancer cells to chemo-drug. Moreover, animal study suggested inhibition of both HP and GPI significantly impeded tumor growth in mice. Collectively, we report for the first time the oncogenic roles of HP, at least partially, through regulating glycolysis and its downstream effector, GPI, contributes in maintaining EMT and chemoresistance in breast cancer.

Functional Implications of Cathelicidin Antimicrobial Protein in Breast Cancer and Tumor-Associated Macrophage Microenvironment.

It is well-established that tumor-associated macrophages (TAMs) play an important role in breast cancer development. Accumulating evidence suggested that human cathelicidin antimicrobial protein (CAMP), which is mainly expressed in host defense cells such as macrophages, is crucial not only in combating microorganisms but also promoting tumor growth. Here we report the interaction of CAMP with TAMs in breast cancer. CAMP expression was upregulated in cancer tissues and in the circulation of breast cancer patients. Surgical removal of tumor decreased CAMP peptide serum level. Knockdown of CAMP decreased cell proliferation and migration/invasion ability in breast cancer cells. CAMP expression was altered during macrophage M1/M2 polarization and was expressed predominantly in M2 phenotype. In addition, breast cancer cells co-cultured with macrophages upregulated CAMP expression and also increased cancer cell viability. Xenograft tumors reduced significantly upon CAMP receptor antagonist treatment. Our data implicated that CAMP confers an oncogenic role in breast cancer and plays an important role in the tumor microenvironment between TAMs and breast cancer cells, and blocking the interaction between them would provide a novel therapeutic option for this malignant disease.

ITGAV targeting as a therapeutic approach for treatment of metastatic breast cancer.

During tumorigenesis and metastasis, integrins regulate localization and activity of proteolytic enzymes that remodel the extracellular matrix. Previous studies have demonstrated blocking of αVß3 to effectively inhibit proliferation, angiogenesis, and the survival of various cancer cell types. However, little is known about the functional role of the integrin subunit alpha-V gene (ITGAV) in metastatic breast cancer. In this study, ITGAV knockdown was used to identify the molecular mechanism by which ITGAV promotes tumorigenesis, metastasis, proliferation, invasion, and cellular self-renewal. The effectiveness of an ITGAV antagonist, cilengitide, for breast cancer treatment was investigated in vivo. Analysis of publicly available data demonstrated that overexpression of ITGAV was associated with poor relapse free survival of breast cancer patients. Silencing of ITGAV inhibited cell proliferation, invasion, and self-renewal of breast cancer cell lines by altering expression of BCL2 and PXN. The use of cilengitide significantly reduced lung metastasis in a metastatic breast cancer animal model. In conclusion, overexpression of ITGAV contributes to breast cancer metastasis through upregulation of PXN. Targeting ITGAV is a potential treatment for metastatic breast cancer as well as primary breast tumors with high ITGAV expression. ITGAV expression levels may be useful predictors of patient treatment and outcome responses.

Long non-coding RNA NEAT1 confers oncogenic role in triple-negative breast cancer through modulating chemoresistance and cancer stemness.

Triple-negative breast cancer (TNBC) is a malignant subtype of breast cancer with the absence of targeted therapy, resulting in poor prognosis in patients. Chemotherapy remains the mainstay of treatment for TNBC; however, development of drug resistance is the main obstacle for successful treatments. In recent years, long non-coding RNA (lncRNA) has been implicated in multiple biological functions in various diseases, particularly cancers. Accumulating evidence suggested that lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) expression is dysregulated in many human cancers and thus is a useful prognostic marker for cancer patients. Nevertheless, the mechanism of how NEAT1 confers drug resistance in TNBC is still largely unknown. We performed lncRNA profiling by the LncRNA Profiler qPCR Array Kit in normal control (NC) and breast cancers (BC) blood samples and further validated in a larger cohort of samples by qRT-PCR. Gene expression level and localization were investigated by qRT-PCR, western blotting, and immunofluorescence staining. Flow cytometric analysis was carried out to detect cancer stem cells. Functional studies were performed both in vitro and in vivo xenograft model. Among 90 lncRNAs, NEAT1 was highly expressed in the blood samples of breast cancer patients than in NC. In particular, the expression of NEAT1 was higher in TNBC tissues than other subgroups. Functional studies revealed that NEAT1 conferred oncogenic role by regulating apoptosis and cell cycle progression in TNBC cells. We identified that knockdown of NEAT1 sensitized cells to chemotherapy, indicating the involvement in chemoresistance. Importantly, shNEAT1 reduced stem cell populations such as CD44+/CD24-, ALDH+, and SOX2+, implicating that NEAT1 was closely related to cancer stemness in TNBC. Our data highlighted the roles of NEAT1 chemoresistance and cancer stemness, suggesting that it could be used as a new clinical therapeutic target for treating TNBC patients especially those with drug resistance.

MiR-92 suppresses proliferation and induces apoptosis by targeting EP4/Notch1 axis in gastric cancer.

MiR-92a has been shown to be dysregulated in various cancers and exhibited differential role in carcinogenesis. In this study, we sought to delineate the functional role of miR-92a and its regulatory pathway in gastric cancer. MiR-92a expression were underexpressed in tissues of gastric cancer patients with the area under curve (AUC) of 0.78. Low expression in plasma was due to the increased promoter DNA methylation of miR-92a. Overexpression of miR-92a inhibited cell proliferation and invasion, and induced apoptosis. Furthermore, miR-92a reduced tumor growth in xenograft model. EP4 and Notch 1 were identified to be negatively regulated by miR-92a, and involved in cell growth. Moreover, NF-κB expression was inversely correlated with miR-92a in gastric cancer tissues and suppressed the expression of miR-92. This study unravels the tumor suppressive role of miR-92a involving EP4/Notch 1 signaling regulated by NF-κB in gastric cancer. Further studies on miR-92a and EP4/Notch1 may provide a new treatment strategy for gastric cancer.

Comprehensive spectrum of BRCA1 and BRCA2 deleterious mutations in breast cancer in Asian countries.

Approximately 5%-10% of breast cancers are due to genetic predisposition caused by germline mutations; the most commonly tested genes are BRCA1 and BRCA2 mutations. Some mutations are unique to one family and others are recurrent; the spectrum of BRCA1/BRCA2 mutations varies depending on the geographical origins, populations or ethnic groups. In this review, we compiled data from 11 participating Asian countries (Bangladesh, Mainland China, Hong Kong SAR, Indonesia, Japan, Korea, Malaysia, Philippines, Singapore, Thailand and Vietnam), and from ethnic Asians residing in Canada and the USA. We have additionally conducted a literature review to include other Asian countries mainly in Central and Western Asia. We present the current pathogenic mutation spectrum of BRCA1/BRCA2 genes in patients with breast cancer in various Asian populations. Understanding BRCA1/BRCA2 mutations in Asians will help provide better risk assessment and clinical management of breast cancer.