Breast Cancer Latest Developments
The field of breast cancer research is a rapidly-moving one especially as this is a very well-funded area of cancer research. To help you find-out the latest news and discovery, the following articles are presented. To learn more, simply click of the article's title:
Breast Cancer Articles
Bone marrow-derived, alternatively-activated macrophages enhance solid tumor growth and lung metastasis of mammary carcinoma cells in a Balb/C mouse orthotopic model
IntroductionTumor-associated macrophages, which are derived from the infiltration of circulating bone marrow-derived monocytes, consist primarily of a polarized M2 macrophage (M2-Mphi) population and are associated with poor prognosis in various cancers. In the present study, we attempted to assess whether M2-Mphis derived from bone marrow stimulate the promotion and progression of mammary tumors. Methods: 4T1 murine mammary carcinoma cells were injected either alone or coupled with M2-Mphis into the mammary fat pads of syngeneic female Balb/C mice. The M2-Mphis were prepared by treating monocytes isolated from female Balb/C mouse bone marrow with interleukin (IL)-4. Tumor cell growth was determined using an in vivo imaging system and the expression of cell proliferation-, angiogenesis-, and lymphangiogenesis-related proteins in tumor tissues was immunohistochemically analyzed. To evaluate the effects of the crosstalk between 4T1 cells and M2-MPhis on the secretion and mRNA expression of cytokines and the migration of monocytes, 4T1 cells and M2-Mphis were co-cultured and cytokine antibody array, real-time reverse transcription-polymerase chain reaction, and transwell migration assays were conducted. Results: The co-injection of M2-Mphis into the mammary fat pads of mice increased solid tumor growth and lung metastasis of 4T1 cells as well as the infiltration of CD45+ leukocytes into tumor tissues. The proportions of Ki-67+ proliferating cells and the expression of hypoxia inducible factor-1alpha, vascular endothelial cell growth factor (VEGF)-A, CD31, VEGF-C, and lymphatic vessel endothelial receptor-1 were increased significantly in the tumor tissues of mice co-injected with 4T1 cells and M2-MPhis. The in vitro results revealed that the proliferation of 4T1 cells, the migration of monocytes, and the secretion of granulocyte-colony stimulating factor, interferon (IFN)-gamma, IL-1alpha, IL-2, IL-16, IFN-gamma-induced protein-10, keratinocyte-derived chemokine, macrophage-colony stimulating factor, monocyte chemotactic protein-1, macrophage inflammatory protein-1alpha, and RANTES (regulated upon activation, normal T-cell expressed and secreted) were increased when 4T1 cells were co-cultured with M2-Mphis, as compared to when the 4T1 cells were cultured alone. Conclusions: The crosstalk between 4T1 cells and M2-Mphis increased the production of cytokines which may have induced immune cell infiltration into tumor tissues, tumor cell proliferation, angiogenesis, and lymph angiogenesis, thereby increasing solid tumor growth and lung metastasis.
MicroRNA-34a and microRNA-21 play roles in the chemopreventive effects of 3,6-dihydroxyflavone on 1-methyl-1-nitrosourea-induced breast carcinogenesis
IntroductionMicroRNAs (miRNAs) are very important regulators in biological processes such as development, cellular differentiation, and carcinogenesis. Given the important role of miRNAs in tumorigenesis and development, it is worth investigating whether some miRNAs play roles in the anticancer mechanism of flavonoids. However, such role has not been reported yet. We have previously selected a promising anti-cancer agent 3,6-dihydroxyflavone (3,6-DHF) in pharmacodynamic experiments, which may serve as a leading compound for developing more potent anticancer drugs or chemopreventive supplements. The present study aims to investigate the chemopreventive activities of 3,6-DHF against mammary carcinogenesis. Methods: The experimental model of breast carcinogenesis was developed by intraperitoneal injection of 1-methyl-1-nitrosourea (MNU). The bioavailability of 3,6-DHF in rats was detected by high performance liquid chromatography (HPLC). The expression of microRNA-34a (miR-34a) and microRNA-21 (miR-21) was evaluated by Real time quantitative reverse transcription PCR (qRT-PCR). Cell apoptosis was analyzed by flow cytometry or Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Mitochondrial membrane potential ([increment]psim) was assayed using 5,5',6,6'-Tetrachloro-1,1',3,3'-tetraethyl- imidacarbocyanine iodide (JC-1) dye by confocal laser scanning microscopy. The level of cytochrome C in cytosol was evaluated by Western blotting. Results: Our study showed that oral administration of 3,6-DHF effectively suppressed MNU-induced breast carcinogenesis in rats, decreasing the cancer incidence by 35.7%. The detection of bioavailability indicated that the concentration of 3,6-DHF was 2.5+/-0.4 mug/ml in the plasma of rats within 2 hours after administration, and was 21.7+/-3.8 mug/ml in the urine within 24 hours. Oral administration of 3,6-DHF to BALB/c nude mice bearing breast cancer cell xenografts also significantly suppressed tumor growth in vivo. Furthermore, our study revealed that the global up-regulation of miR-21 and down-regulation of miR-34a in breast carcinogenesis could be reversed by 3,6-DHF, which significantly up-regulated miR-34a expression and decreased miR-21 expression; inducing apoptosis of breast cancer cells in vitro and in vivo. Overexpression of miR-34a induced by plasmid transfection or inhibition of miR-21 by oligonucleotides markedly promoted the pro-apoptotic effect of 3,6-DHF. Inactivation of miR-34a or over-production of miR-21 compromised the anticancer effects of 3,6-DHF. Conclusions: These findings indicate that 3,6-DHF is a potent natural chemopreventive agent, and that miR-34a and miR-21 play roles in MNU-induced breast carcinogenesis and the anticancer mechanism of flavonoids.
Back to embryonic stage: Nodal as a biomarker for breast cancer progression
The TGF-beta member, the embryonic morphogen, Nodal, is not expressed in the majority of normal adult tissues. However, there is a growing body of evidence indicating that Nodal expression re-emerges in a number of human cancers, including melanoma, glioma, endometrial, and prostate cancers. Reactivation of Nodal signaling in these tumors contribute to their aggressiveness. In the paper by Strizzi and colleagues published in this issue of Breast Cancer Research, this group investigates the clinical significance of Nodal expression in breast cancer. They report that Nodal expression is significantly greater in malignant versus benign breast disease. More importantly, Nodal levels correlated with grading, staging and lymph node involvement, independent of the ER/PR or HER2 status. Collectively, these data suggest that Nodal could serve as a potential biomarker for invasive disease and a potential therapeutic target in breast cancer.
Targeting triple-negative breast cancer cells with the HDAC inhibitor Panobinostat
IntroductionOf the more than one million global cases of breast cancer diagnosed each year, approximately fifteen percent are characterized as triple-negative, lacking the estrogen, progesterone, and Her2/neu receptors. Lack of effective therapies, younger age at onset, and early metastatic spread have contributed to the poor prognoses and outcomes associated with these malignancies. Here, we investigate the ability of the histone deacetylase inhibitor panobinostat (LBH589) to selectively target triple-negative breast cancer (TNBC) cell proliferation and survival in vitro and tumorigenesis in vivo. Methods: TNBC cell lines MDA-MB-157, MDA-MB-231, MDA-MB-468, and BT-549 were treated with nanomolar (nM) quantities of panobinostat. Relevant histone acetylation was verified by flow cytometry and immunofluorescent imaging. Assays for trypan blue viability, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) proliferation, and DNA fragmentation were used to evaluate overall cellular toxicity. Changes in cell cycle progression were assessed with propidium iodide flow cytometry. Additionally, qPCR arrays were used to probe MDA-MB-231 cells for panobinostat-induced changes in cancer biomarkers and signaling pathways. Orthotopic MDA-MB-231 and BT-549 mouse xenograft models were used to assess the effects of panobinostat on tumorigenesis. Lastly, flow cytometry, ELISA, and immunohistochemical staining were applied to detect changes in cadherin-1, E-cadherin (CDH1) protein expression and the results paired with confocal microscopy in order to examine changes in cell morphology. Results: Panobinostat treatment increased histone acetylation, decreased cell proliferation and survival, and blocked cell cycle progression at G2/M with a concurrent decrease in S phase in all TNBC cell lines. Treatment also resulted in apoptosis induction at 24 hours in all lines except the MDA-MB-468 cell line. MDA-MB-231 and BT-549 tumor formation was significantly inhibited by panobinostat (10 mg/kg/day) in mice. Additionally, panobinostat up-regulated CDH1 protein in vitro and in vivo and induced cell morphology changes in MDA-MB-231 cells consistent with reversal of the mesenchymal phenotype. Conclusions: This study revealed that panobinostat is overtly toxic to TNBC cells in vitro and decreases tumorigenesis in vivo. Additionally, treatment up-regulated anti-proliferative, tumor suppressor, and epithelial marker genes in MDA-MB-231 cells and initiated a partial reversal of the epithelial-to-mesenchymal transition. Our results demonstrate a potential therapeutic role of panobinostat in targeting aggressive triple-negative breast cancer cell types.
Preclinical and clinical studies of estrogen deprivation support the PDGF/Abl pathway as a novel therapeutic target for overcoming endocrine resistance in breast cancer
IntroductionThe majority of breast tumors at primary diagnosis are estrogen receptor positive (ER+). Estrogen (E) mediates its effects by binding to the ER. Therapies targeting the estrogenic stimulation of tumor growth reduce mortality from ER+ breast cancer. However, resistance remains a major clinical problem. Methods: To identify molecular mechanisms associated with resistance to E-deprivation, we assessed the temporal changes in global gene expression during adaptation to long-term culture of MCF7 human breast cancer cells in the absence of estradiol (E2), long term estrogen deprived (LTED), that leads to recovery of proliferative status and models resistance to an aromatase inhibitor (AI). The expression levels of proteins were determined by western blotting. Proliferation assays were carried out using the dual platelet derived growth factor receptor (PDGFR)/Abelson tyrosine kinase (Abl) inhibitor nilotinib. To determine effects on ER-mediated transactivation luciferase reporter assays were used. Changes in recruitment of cofactors to the gene regulated by estrogen in breast cancer 1 (GREB1) promoter were determined by Chromatin immunoprecipitation (ChIP). Gene expression data were derived from 81 postmenopausal women with ER+ BC pre-treatment and at 2-weeks post-treatment with single agent anastrozole in a neoadjuvant trial. Results: The PDGF/Abl canonical pathway was significantly elevated as early as 1 week post E-deprivation (P=1.94 E-04) and this became the top adaptive pathway at the point of proliferative recovery (P=1.15 E-07). Both PDGFR-beta and Abl protein levels were elevated in the LTED cells compared to wild type (wt)-MCF7 cells. The PDGF/Abl tyrosine kinase inhibitor nilotinib, suppressed proliferation in LTED cells in the presence or absence of E. Nilotinib also suppressed ER-mediated transcription by destabilizing the ER and reducing recruitment of amplified in breast cancer-1 (AIB1) and the center blocking peptide (CBP) to the promoter of the E-responsive gene GREB1. High PDGFR-beta in primary ER+ breast cancer of 81 patients prior to neoadjuvant treatment with an AI was associated with poorer antiproliferative response. Additionally PDGFR-beta expression increased after two weeks of AI therapy (1.25 fold, P=0.003). Conclusions: These preclinical and clinical data indicate that the PDGF/Abl signaling pathway merits clinical evaluation as a therapeutic target with endocrine therapy in ER+ breast cancer.
Downregulation of the tumor-suppressor miR-16 via progestin-mediated oncogenic signaling contributes to breast cancer development
IntroductionExperimental and clinical evidence points to a critical role of progesterone and the nuclear progesterone receptor (PR) in controlling mammary gland tumorigenesis. However, the molecular mechanisms of progesterone action in breast cancer still remain elusive. On the other hand, micro RNAs (miRNAs) are short ribonucleic acids which have also been found to play a pivotal role in cancer pathogenesis. The role of miRNA in progestin-induced breast cancer is poorly explored. In this study we explored progestin modulation of miRNA expression in mammary tumorigenesis. Methods: We performed a genome-wide study to explore progestin-mediated regulation of miRNA expression in breast cancer. miR-16 expression was studied by RT-qPCR in cancer cell lines with silenced PR, signal transducer and activator of transcription 3 (Stat3) or c-Myc, treated or not with progestins. Breast cancer cells were transfected with the precursor of miR-16 and proliferation assays, Western blots or in vivo experiments were performed. Target genes of miR-16 were searched through a bioinformatical approach, and the study was focused on cyclin E. Reporter gene assays were performed to confirm that cyclin E 3'UTR is a direct target of miR-16. Results: We found that 9 miRNAs were upregulated and 7 were downregulated by progestin in mammary tumor cells. miR-16, whose function as a tumor suppressor in leukemia has already been shown, was identified as one of the downregulated miRNAs in murine and human breast cancer cells. Progestin induced a decrease in miR-16 levels via the classical PR and through a hierarchical interplay between Stat3 and the oncogenic transcription factor c-Myc. A search for miR-16 targets showed that the CCNE1 gene, encoding the cell cycle regulator cyclin E, contains conserved putative miR-16 target sites in its mRNA 3' UTR region. We found that, similar to the molecular mechanism underlying progestin-modulated miR-16 expression, Stat3 and c-Myc participated in the induction of cyclin E expression by progestin. Moreover, overexpression of miR-16 abrogated the ability of progestin to induce cyclin E upregulation, revealing that cyclin E is a novel target of miR-16 in breast cancer. Overexpression of miR-16 also inhibited progestin-induced breast tumor growth in vitro and in vivo, demonstrating for the first time, a role for miR-16 as a tumor suppressor in mammary tumorigenesis. We also found that the ErbB ligand heregulin (HRG) downregulated the expression of miR-16, which then participates in the proliferative activity of HRG in breast tumor cells. Conclusions: In this study, we reveal the first progestin-regulated miRNA expression profile and identify a novel role for miR-16 as a tumor suppressor in progestin- and growth factor-induced growth in breast cancer.
Adiposity, hormone replacement therapy use and breast cancer risk by age and hormone receptor status: a large prospective cohort study
IntroductionAssociations of hormone-receptor positive breast cancer with excess adiposity are reasonably well characterized; however, uncertainty remains regarding the association of body mass index (BMI) with hormone-receptor negative malignancies, and possible interactions by hormone replacement therapy (HRT) use. Methods: Within the European EPIC cohort, Cox proportional hazards models were used to describe the relationship of BMI, waist and hip circumferences with risk of estrogen receptor (ER)-progesterone receptor (PR)- (n=1,021) and ER+PR+ (n=3,586) breast tumors within five-year age bands. Among postmenopausal women, the joint effects of BMI and HRT use were analyzed. Results: For risk of ER-PR- tumors, there was no association of BMI across the age bands. However, when analyses were restricted to postmenopausal HRT never users, a positive risk association with BMI (3rd versus 1st tertile HR=1.47[1.01-2.15]) was observed. BMI was inversely associated with ER+PR+ tumors among women aged [less than or equal to]49 years (per 5kg/m2 increase, HR=0.79[95%CI 0.68-0.91]), and positively associated with risk among women [greater than or equal to]65 years (HR=1.25[1.16-1.34]). Adjusting for BMI, waist and hip circumferences showed no further associations with risks of breast cancer subtypes. Current use of HRT was significantly associated with an increased risk of receptor-negative (HRT current use compared to HRT never use HR: 1.30[1.05-1.62]) and positive tumors (HR: 1.74[1.56-1.95]), although this risk increase was weaker for ER-PR- disease (Phet=0.035). The association of HRT was significantly stronger in the leaner women (BMI [less than or equal to]22.5kg/m2) than for more overweight women (BMI [greater than or equal to]25.9kg/m2) for, both, ER-PR- (HR: 1.74[1.15-2.63]) and ER+PR+ (HR: 2.33[1.84-2.92]) breast cancer and was not restricted to any particular HRT regime. Conclusions: An elevated BMI may be positively associated with risk of ER-PR- tumors, among postmenopausal women who never used HRT. Furthermore, postmenopausal HRT users were at an increased risk of ER-PR- as well as ER+PR+ tumors, especially among leaner women. For HR-positive tumors, but not for HR-negative tumors, our study confirms an inverse association of risk with BMI among young women of premenopausal age. Our data provide evidence for a possible role of sex hormones in the etiology of HR-negative tumors.
Potential for the embryonic morphogen Nodal as a prognostic and predictive biomarker in breast cancer
IntroductionThe re-emergence of the tumour growth factor-beta (TGF-beta)-relatedembryonic morphogen Nodal has recently been reported in several different human cancers. In this study, we examined the expression of Nodal in a series of benign and malignant human breast tissues to determine the clinical significance of this expression and whether Nodal could represent a potential therapeutic target in breast cancer. Methods: Tissue sections from 431 therapeutically naive patients diagnosed with benign or malignant breast disease were stained for Nodal by immunohistochemistry and analysed in a blinded manner. The degree of Nodal staining was subsequently correlated with available clinical data, such as diagnoses and disease stage. These tissue findings were further explored in breast cancer cell lines MDA-MB-231 and MDAMB- 468 treated with a Nodal blocking antibody to determine biological effects for target validation. Results: A variable degree of Nodal staining was detected in all samples. The intensity of Nodal staining was significantly greater in undifferentiated, advanced stage, invasive breast cancer compared with benign breast disease or early stage breast cancer. Treatment of human breast cancer cells in vitro with Nodal blocking antibody significantly reduced proliferation and colony-forming ability in soft agar, concomitant with increased apoptosis. Conclusions: These data suggest a potential role for Nodal as a biomarker for disease progression and a promising target for anti-Nodal therapy in breast cancer.
Estrogen related receptor alpha: an orphan finds a family
Identification of molecules and their effectors has led to new therapies designed to specifically inhibit pathways in molecularly defined breast cancer subtypes. An orphan nuclear receptor, estrogen-related receptor alpha, has been shown to be a downstream target of two tyrosine kinase growth factor receptors: human epidermal growth factor receptor 2 and the type I insulin-like growth factor receptor. Identifying the mechanistic actions of orphan nuclear receptors could lead to new biomarkers and molecular targets in malignancy.
Crk adaptor proteins act as key signaling integrators for breast tumorigenesis
IntroductionCT10 regulator of kinase (Crk) adaptor proteins (CrkI, CrkII and CrkL) play a role in integrating signals for migration and invasion of highly malignant breast cancer cell lines. This has important implications, as elevated CrkI/II protein levels were observed in a small cohort of breast cancer patients, which identified a potential role for Crk proteins in breast cancer progression. Numerous in vitro studies identified a role for Crk proteins in cell motility, but little is known about how Crk proteins contribute to breast cancer progression in vivo. Methods: The clinical significance of Crk proteins in human breast cancer was assessed by analyzing published breast cancer datasets using a gene expression signature that was generated following CrkII over-expression, and by examining Crk protein expression in tissue microarrays of breast tumors (n=254). Stable knockdown of Crk (CrkI/CrkII/CrkL) proteins was accomplished using an shRNA-mediated approach in two basal breast cancer cell lines, MDA-231 1833TR and SUM1315, where the former have a high affinity to form bone metastases. Both in vitro assays (cell migration, invasion, soft agar growth) and in vivo experiments (intra-cardiac, tibial and mammary fat pad injections) were performed to assess the functional significance of Crk proteins in breast cancer. Results: A gene signature derived following CrkII over-expression correlated significantly with basal breast cancers and with high grade and poor outcome in general. Moreover, elevated Crk immunostaining on tissue microarrays revealed a significant association with highly proliferative tumors within the basal subtype. RNAi-mediated knockdown of all three Crk proteins in metastatic basal breast cancer cells established a continued requirement for Crk in cell migration and invasion in vitro and metastatic growth in vivo. Furthermore, Crk ablation suppressed anchorage independent growth and in vivo orthotopic tumor growth. This was associated with diminished cell proliferation and was rescued by expression of non-shRNA targeted CrkI/II. Perturbations in tumor progression correlated with altered integrin signaling, including decreased cell spreading, diminished p130Cas phosphorylation, and Cdc42 activation. Conclusions: These data highlight the physiological importance of Crk proteins in regulating growth of aggressive basal breast cancer cells, and identify Crk-dependent signaling networks as promising therapeutic targets.