Paracrine control of milk protein gene expression in tammar wallaby

Stephen utilised the unique lactation strategy of the tammar wallaby to identify factors within the mammary gland that determine the composition of milk and how the milk composition changes throughout lactation in order to provide immunity both to the nursing mammary gland and the suckling.

Breast cancer prognosis risk estimation using integrated gene expression and clinical data

Novel prognostic markers are needed so newly diagnosed breast cancer patients do not undergo any unnecessary therapy. Various microarray gene expression datasets based studies have generated gene signatures to predict the prognosis outcomes, while ignoring the large amount of information contained in established clinical markers. Nevertheless, small sample sizes in individual microarray datasets remain a bottleneck in generating robust gene signatures that show limited predictive power. The aim of this study is to achieve high classification accuracy for the good prognosis group and then achieve high classification accuracy for the poor prognosis group.

Differential temporal expression of milk miRNA during the lactation cycle of the marsupial tammar wallaby (Macropus eugenii)

Lactation is a key aspect of mammalian evolution for adaptation of various reproductive strategies along different mammalian lineages. Marsupials, such as tammar wallaby, adopted a short gestation and a relatively long lactation cycle, the newborn is immature at birth and significant development occurs postnatally during lactation. Continuous changes of tammar milk composition may contribute to development and immune protection of pouch young. Here, in order to address the putative contribution of newly identified secretory milk miRNA in these processes, high throughput sequencing of miRNAs collected from tammar milk at different time points of lactation was conducted. A comparative analysis was performed to find distribution of miRNA in milk and blood serum of lactating wallaby.

IPA: Integrated predictive gene signature from gene expression based breast cancer patient samples

Background: Novel predictive markers are needed to accurately diagnose the breast cancer patients so they do not need to undergo any unnecessary aggressive therapies. Various gene expression studies based predictive gene signatureshave generated in the recent past to predict the binary estrogen-receptor subclass or to predict the therapy response subclass. However, the existing algorithms comes with many limitations, including low predictive performances over multiple cohorts of patients and non-significant or limited biological roles associated with thepredictive gene signatures. Therefore, the aim of this study is to develop novel predictive markers with improved performances.Methods: We propose a novel prediction algorithm called IPA to construct a predictive gene signature for performing multiple prediction tasks of predicting estrogen-receptor based binary subclass and predicting chemotherapy response (neoadjuvantly) based binary subclass. The constructed gene signature with considering multiple classification techniques was used to evaluate the algorithm performance on multiple cohorts of breast cancer patients.Results: The evaluation on multiple validation cohorts demonstrated that proposed algorithm achieved stable and high performance to perform prediction tasks, with consideration given to any classification techniques. We show that the predictive gene signature of our proposed algorithm reflects the mechanisms underlying the estrogen-receptors or response to therapy with significant greater biological interpretations, compared with the other existing algorithm.

Tumour but not stromal expression of β3 integrin is essential, and is required early, for spontaneous dissemination of bone-metastatic breast cancer.

Although many preclinical studies have implicated β3 integrin receptors (αvβ3 and αIIbβ3) in cancer progression, β3 inhibitors have shown only modest efficacy in patients with advanced solid tumours. The limited efficacy of β3 inhibitors in patients could arise from our incomplete understanding of the precise function of β3 integrin and, consequently, inappropriate clinical application. Data from animal studies are conflicting and indicate heterogeneity with respect to the relative contributions of β3-expressing tumour and stromal cell populations in different cancers. Here we aimed to clarify the function and relative contributions to metastasis of tumour versus stromal β3 integrin in clinically relevant models of spontaneous breast cancer metastasis, with particular emphasis on bone metastasis. We show that stable down-regulation of tumour β3 integrin dramatically impairs spontaneous (but not experimental) metastasis to bone and lung without affecting primary tumour growth in the mammary gland. Unexpectedly, and in contrast to subcutaneous tumours, orthotopic tumour vascularity, growth and spontaneous metastasis were not altered in mice null for β3 integrin. Tumour β3 integrin promoted migration, protease expression and trans-endothelial migration in vitro and increased vascular dissemination in vivo, but was not necessary for bone colonization in experimental metastasis assays. We conclude that tumour, rather than stromal, β3 expression is essential and is required early for efficient spontaneous breast cancer metastasis to bone and soft tissues. Accordingly, differential gene expression analysis in cohorts of breast cancer patients showed a strong association between high β3 expression, early metastasis and shorter disease-free survival in patients with oestrogen receptor-negative tumours. We propose that β3 inhibitors may be more efficacious if used in a neoadjuvant setting, rather than after metastases are established. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Iron-free and iron-saturated bovine lactoferrin inhibit survivin expression and differentially modulate apoptosis in breast cancer

BACKGROUND: Iron binding, naturally occurring protein bovine lactoferrin (bLf) has attracted attention as a safe anti-cancer agent capable of inducing apoptosis. Naturally, bLf exists partially saturated (15-20%) with Fe(3+) however, it has been demonstrated that manipulating the saturation state can enhance bLf's anti-cancer activities. METHODS: Apo-bLf (Fe(3+) free) and Fe-bLf (>90% Fe(3+) Saturated) were therefore, tested in MDA-MB-231 and MCF-7 human breast cancer cells in terms of cytotoxicity, proliferation, migration and invasion. Annexin-V Fluos staining was also employed in addition to apoptotic protein arrays and Western blotting to determine the specific mechanism of bLf-induced apoptosis with a key focus on p53 and inhibitor of apoptosis proteins (IAP), specifically survivin. RESULTS: Apo-bLf induced significantly greater cytotoxicity and reduction in cell proliferation in both cancer cells showing a time and dose dependent effect. Importantly, no cytotoxicity was detected in normal MCF-10-2A cells. Both forms of bLf significantly reduced cell invasion in cancer cells. Key apoptotic molecules including p53, Bcl-2 family proteins, IAP members and their inhibitors were significantly modulated by both forms of bLf, though differentially in each cell line. Most interestingly, both Apo-bLf and Fe-bLf completely inhibited the expression of survivin protein (key IAP), after 48 h at 30 and 40 nM in cancer cells. CONCLUSIONS: The capacity of these forms of bLf to target survivin expression and modulation of apoptosis demonstrates an exciting potential for bLf as an anti-cancer therapeutic in the existing void of survivin inhibitors, with a lack of successful inhibitors in the clinical management of cancer.

Altered expression of two zinc transporters, SLC30A5 and SLC30A6, underlies a mammary gland disorder of reduced zinc secretion into milk

Two cases of zinc deficiency in breastfed neonates were investigated where zinc levels in the mothers' milk were reduced by more than 75 % compared to normal. The objective of this study was to find the molecular basis of the maternal zinc deficiency condition. Significant reductions in mRNA expression and protein levels of the zinc transporters SLC30A5 and SLC30A6 were found in maternal tissue, suggesting a causal link to the zinc-deficient milk. Novel splice variants of the SLC30A6 transcript were detected. No modifications were found in coding regions, or in transcription binding sites of promoter regions or in 5' and 3' untranslated regions of both transporters in lymphoblasts and fibroblasts isolated from both mothers. Altered DNA methylation in SLC30A5 at two CpG sites was detected and may account for the reduced levels of SLC30A5 mRNA and protein in lymphoblasts. Reduced SLC30A6 mRNA and protein levels in lymphoblasts may be secondary to reduced SLC30A5 expression, as they function as a heterodimer in zinc transport. In conclusion, two cases of zinc deficiency are linked to low levels of the SLC30A5 and SLC30A6 zinc transporters. These two zinc transporters have not been previously associated with zinc deficiency in milk.

Biodegradable Eri silk nanoparticles as a delivery vehicle for bovine lactoferrin against MDA-MB-231 and MCF-7 breast cancer cells

This study used the Eri silk nanoparticles (NPs) for delivering apo-bovine lactoferrin (Apo-bLf) (~2% iron saturated) and Fe-bLf (100% iron saturated) in MDA-MB-231 and MCF-7 breast cancer cell lines. Apo-bLf and Fe-bLf-loaded Eri silk NPs with sizes between 200 and 300 nm (±10 nm) showed a significant internalization within 4 hours in MDA-MB-231 cells when compared to MCF-7 cells. The ex vivo loop assay with chitosan-coated Fe-bLf-loaded silk NPs was able to substantiate its future use in oral administration and showed the maximum absorption within 24 hours by ileum. Both Apo-bLf and Fe-bLf induced increase in expression of low-density lipoprotein receptor-related protein 1 and lactoferrin receptor in epidermal growth factor (EGFR)-positive MDA-MB-231 cells, while transferrin receptor (TfR) and TfR2 in MCF-7 cells facilitated the receptor-mediated endocytosis of NPs. Controlled and sustained release of both bLf from silk NPs was shown to induce more cancer-specific cytotoxicity in MDA-MB-231 and MCF-7 cells compared to normal MCF-10A cells. Due to higher degree of internalization, the extent of cytotoxicity and apoptosis was significantly higher in MDA-MB-231 (EGFR+) cells when compared to MCF-7 (EGFR-) cells. The expression of a prominent anticancer target, survivin, was found to be downregulated at both gene and protein levels. Taken together, all the observations suggest the potential use of Eri silk NPs as a delivery vehicle for an anti-cancer milk protein, and indicate bLf for the treatment of breast cancer.

Inhibition of HDAC3- and HDAC6-promoted survivin expression plays an important role in SAHA-induced autophagy and viability reduction in breast cancer cells

SAHA is a class I HDAC/HDAC6 co-inhibitor and an autophagy inducer currently undergoing clinical investigations in breast cancer patients. However, the molecular mechanism of action of SAHA in breast cancer cells remains unclear. In this study, we found that SAHA is equally effective in targeting cells of different breast cancer subtypes and tamoxifen sensitivity. Importantly, we found that down-regulation of survivin plays an important role in SAHA-induced autophagy and cell viability reduction in human breast cancer cells. SAHA decreased survivin and XIAP gene transcription, induced survivin protein acetylation and early nuclear translocation in MCF7 and MDA-MB-231 breast cancer cells. It also reduced survivin and XIAP protein stability in part through modulating the expression and activation of the 26S proteasome and heat-shock protein 90. Interestingly, targeting HDAC3 and HDAC6, but not other HDAC isoforms, by siRNA/pharmacological inhibitors mimicked the effects of SAHA in modulating the acetylation, expression, and nuclear translocation of survivin and induced autophagy in MCF7 and MDA-MB-231 cancer cells. Targeting HDAC3 also mimicked the effect of SAHA in up-regulating the expression and activity of proteasome, which might lead to the reduced protein stability of survivin in breast cancer cells. In conclusion, this study provides new insights into SAHA's molecular mechanism of actions in breast cancer cells. Our findings emphasize the complexity of the regulatory roles in different HDAC isoforms and potentially assist in predicting the mechanism of novel HDAC inhibitors in targeted or combinational therapies in the future.

Epidermal growth factor-induced epithelio-mesenchymal transition in human breast carcinoma cells

PMC42-LA cells display an epithelial phenotype: the cells congregate into pavement epithelial sheets in which E-cadherin and beta-catenin are localized at cell-cell borders. They abundantly express cytokeratins, although 5% to 10% of the cells also express the mesenchymal marker vimentin. Stimulation of PMC42-LA cells with epidermal growth factor (EGF) leads to epithelio-mesenchymal transition-like changes including up-regulation of vimentin and down-regulation of E-cadherin. Vimentin expression is seen in virtually all cells, and this increase is abrogated by treatment of cells with an EGF receptor antagonist. The expression of the mesenchyme-associated extracellular matrix molecules fibronectin and chondroitin sulfate proteoglycan also increase in the presence of EGF. PMC42-LA cells adhere rapidly to collagen I, collagen IV, and laminin-1 substrates and markedly more slowly to fibronectin and vitronectin. EGF increases the speed of cell adhesion to most of these extracellular matrix molecules without altering the order of adhesive preference. EGF also caused a time-dependent increase in the motility of PMC42-LA cells, commensurate with the degree of vimentin staining. The increase in motility was at least partly chemokinetic, because it was evident both with and without chemoattractive stimuli. Although E-cadherin staining at cell-cell junctions disappeared in response to EGF, beta-catenin persisted at the cell periphery. Further analysis revealed that N-cadherin was present at the cell-cell junctions of untreated cells and that expression was increased after EGF treatment. N- and E-cadherin are not usually coexpressed in human carcinoma cell lines but can be coexpressed in embryonic tissues, and this may signify an epithelial cell population prone to epithelio-mesenchymal-like responses.

Myoepithelial molecular markers in human breast carcinoma PMC42-LA cells are induced by extracellular matrix and stromal cells

The microenvironment plays a key role in the cellular differentiation of the two main cell lineages of the human breast, luminal epithelial, and myoepithelial. It is not clear, however, how the components of the microenvironment control the development of these cell lineages. To investigate how lineage development is regulated by 3-D culture and microenvironment components, we used the PMC42-LA human breast carcinoma cell line, which possesses stem cell characteristics. When cultured on a two-dimensional glass substrate, PMC42-LA cells formed a monolayer and expressed predominantly luminal epithelial markers, including cytokeratins 8, 18, and 19; E-cadherin; and sialomucin. The key myoepithelial-specific proteins alpha-smooth muscle actin and cytokeratin 14 were not expressed. When cultured within Engelbreth-Holm- Swarm sarcoma-derived basement membrane matrix (EHS matrix), PMC42-LA cells formed organoids in which the expression of luminal markers was reduced and the expression of other myoepithelial-specific markers (cytokeratin 17 and P-cadherin) was promoted. The presence of primary human mammary gland fibroblasts within the EHS matrix induced expression of the key myoepithelial-specific markers, alpha-smooth muscle actin and cytokeratin 14. Immortalized human skin fibroblasts were less effective in inducing expression of these key myoepithelial-specific markers. Confocal dual-labeling showed that individual cells expressed luminal or myoepithelial proteins, but not both. Conditioned medium from the mammary fibroblasts was equally effective in inducing myoepithelial marker expression. The results indicate that the myoepithelial lineage is promoted by the extracellular matrix, in conjunction with products secreted by breast-specific fibroblasts. Our results demonstrate a key role for the breast microenvironment in the regulation of breast lineage development.

Induction of epithelial to mesenchymal transition in PMC42-LA human breast carcinoma cells by carcinoma-associated fibroblast secreted factors

Background
Breast carcinoma is accompanied by changes in the acellular and cellular components of the microenvironment, the latter typified by a switch from fibroblasts to myofibroblasts.


Methods
We utilised conditioned media cultures, Western blot analysis and immunocytochemistry to investigate the differential effects of normal mammary fibroblasts (NMFs) and mammary cancer-associated fibroblasts (CAFs) on the phenotype and behaviour of PMC42-LA breast cancer cells. NMFs were obtained from a mammary gland at reduction mammoplasty, and CAFs from a mammary carcinoma after resection.


Results
We found greater expression of myofibroblastic markers in CAFs than in NMFs. Medium from both CAFs and NMFs induced novel expression of α-smooth muscle actin and cytokeratin-14 in PMC42-LA organoids. However, although conditioned media from NMFs resulted in distribution of vimentin-positive cells to the periphery of PMC42-LA organoids, this was not seen with CAF-conditioned medium. Upregulation of vimentin was accompanied by a mis-localization of E-cadherin, suggesting a loss of adhesive function. This was confirmed by visualizing the change in active β-catenin, localized to the cell junctions in control cells/cells in NMF-conditioned medium, to inactive β-catenin, localized to nuclei and cytoplasm in cells in CAF-conditioned medium.


Conclusion
We found no significant difference between the influences of NMFs and CAFs on PMC42-LA cell proliferation, viability, or apoptosis; significantly, we demonstrated a role for CAFs, but not for NMFs, in increasing the migratory ability of PMC42-LA cells. By concentrating NMF-conditioned media, we demonstrated the presence of factor(s) that induce epithelial-mesenchymal transition in NMF-conditioned media that are present at higher levels in CAF-conditioned media. Our in vitro results are consistent with observations in vivo showing that alterations in stroma influence the phenotype and behaviour of surrounding cells and provide evidence for a role for CAFs in stimulating cancer progression via an epithelial-mesenchymal transition. These findings have implications for our understanding of the roles of signalling between epithelial and stromal cells in the development and progression of mammary carcinoma.

Low-dose metronomic paclitaxel chemotherapy suppresses breast tumors and metastases in mice

This study investigated the use of low-dose metronomic (LDM) chemotherapy with paclitaxel in a highly metastatic mouse model of 4T1 breast cancers, and compared it with the maximum tolerable dose (MTD) therapy. LDM therapy displayed a stronger anti-tumor activity in suppressing primary and metastatic breast tumors with less degree of side effects, and stronger anti-angiogenic and anti-lymphangiogenic activities than MTD therapy. But MTD therapy showed stronger pro-apoptotic and anti-proliferative activities in situ. Paclitaxel therapy downregulated expression of vascular endothelial growth factor receptor-2 (VEGFR2) and up-regulated expression of thrombospondin-1. The results support the application of paclitaxel LDM therapy to treat advanced breast cancer.