Multiple differentiation pathways of rat mammary stromal cells in vitro: acquisition of a fibroblast, adipocyte or endothelial phenotype is dependent on hormonal and extracellular matrix stimulation

S100A4 (metastasin) positive mesenchymal canine mammary tumour spheroids reduce Tenascin C synthesis under DMSO exposure in vitro

In breast cancer research S100A4-positive tumour-associated stromal cells are assumed as primary source of Tenascin C (TNC) in the metastatic environment. Aim of the present study was to isolate and characterize S100A4/TNC positive stromal canine mammary tumour (CMT) cells. Cells grown as scaffold-free spheroids were investigated for S100A4, TNC, and proliferative activity under 1.8% DMSO stimulation by means of Western blot and immunohistochemistry. DMSO is a commonly used drug solvent despite well-known side effects on cells including TNC expression. DMSO did not affect proliferation, but TNC was significantly reduced under DMSO exposure for 7 and 14 days, whereby for S100A4 a reducing effect was only observed after 14 days. Without DMSO, cells stably expressed TNC and S100A4 which makes them suitable to be used in experimental approaches requiring S100A4/TNC expressing CMT stromal cells. Results show that 1.8% DMSO should not be used as solvent for experiments concerning TNC/S100A4 expression.

Mammographically dense human breast tissue stimulates MCF10DCIS.com progression to invasive lesions and metastasis

Background

High mammographic density (HMD) not only confers a significantly increased risk of breast cancer (BC) but also is associated with BCs of more advanced stages. However, it is unclear whether BC progression and metastasis are stimulated by HMD. We investigated whether patient-derived HMD breast tissue could stimulate the progression of MCF10DCIS.com cells compared with patient-matched low mammographic density (LMD) tissue.

Methods

Sterile breast specimens were obtained immediately after prophylactic mastectomy from high-risk women (n = 10). HMD and LMD regions of each specimen were resected under radiological guidance. Human MCF10DCIS.com cells, a model of ductal carcinoma in situ (DCIS), were implanted into silicone biochambers in the groins of severe combined immunodeficiency mice, either alone or with matched LMD or HMD tissue (1:1), and maintained for 6 weeks. We assessed biochamber weight as a measure of primary tumour growth, histological grade of the biochamber material, circulating tumour cells and metastatic burden by luciferase and histology. All statistical tests were two-sided.

Results

HMD breast tissue led to increased primary tumour take, increased biochamber weight and increased proportions of high-grade DCIS and grade 3 invasive BCs compared with LMD. This correlated with an increased metastatic burden in the mice co-implanted with HMD tissue.

Conclusions

Our study is the first to explore the direct effect of HMD and LMD human breast tissue on the progression and dissemination of BC cells in vivo. The results suggest that HMD status should be a consideration in decision-making for management of patients with DCIS lesions.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-016-0767-4) contains supplementary material, which is available to authorized users.

Evidence that breast tissue stiffness is associated with risk of breast cancer

Background

Evidence from animal models shows that tissue stiffness increases the invasion and progression of cancers, including mammary cancer. We here use measurements of the volume and the projected area of the compressed breast during mammography to derive estimates of breast tissue stiffness and examine the relationship of stiffness to risk of breast cancer.

Methods

Mammograms were used to measure the volume and projected areas of total and radiologically dense breast tissue in the unaffected breasts of 362 women with newly diagnosed breast cancer (cases) and 656 women of the same age who did not have breast cancer (controls). Measures of breast tissue volume and the projected area of the compressed breast during mammography were used to calculate the deformation of the breast during compression and, with the recorded compression force, to estimate the stiffness of breast tissue. Stiffness was compared in cases and controls, and associations with breast cancer risk examined after adjustment for other risk factors.

Results

After adjustment for percent mammographic density by area measurements, and other risk factors, our estimate of breast tissue stiffness was significantly associated with breast cancer (odds ratio = 1.21, 95% confidence interval = 1.03, 1.43, p = 0.02) and improved breast cancer risk prediction in models with percent mammographic density, by both area and volume measurements.

Conclusion

An estimate of breast tissue stiffness was associated with breast cancer risk and improved risk prediction based on mammographic measures and other risk factors. Stiffness may provide an additional mechanism by which breast tissue composition is associated with risk of breast cancer and merits examination using more direct methods of measurement.

Pseudotyping the adenovirus serotype 5 capsid with both the fibre and penton of serotype 35 enhances vascular smooth muscle cell transduction

Ex vivo gene therapy during coronary artery bypass grafting (CABG) holds great potential to prevent excessive smooth muscle cell (SMC) proliferation, neointima formation and graft failure. The most successful preclinical strategies to date have utilised vectors based on the species C adenovirus, Ad5, which engages the Coxsackie and Adenovirus receptor (CAR) as its primary attachment receptor. Profiling receptors on human SMCs demonstrated the absence of CAR but substantial expression of the species B receptor CD46. We performed transduction experiments using Ad5 and the CD46-utilising adenovirus Ad35, and found Ad35 significantly more efficient at transducing SMCs. To evaluate whether transduction could be further augmented, we evaluated chimeric CD46-utilising Ad5/Ad35 vectors comprising the Ad5 capsid pseudotyped with the Ad35 fibre alone (Ad5/F35) or in combination with the Ad35 penton (Ad5/F35/P35). In human smooth muscle cells (hSMCs), Ad5/F35/P35 mediated significantly higher levels of transduction than either parental vector or Ad5/F35. Ex vivo transduction experiments using mouse aortas from CD46 transgenics demonstrated that Ad5/F35/P35 was significantly more efficient at transducing SMCs than the other vectors tested. Finally, ex vivo transduction and immunofluorescent colocalisation experiments using human tissue from CABG procedures confirmed the preclinical potential of Ad5/F35/P35 as an efficient vector for vascular transduction during CABG.

Extracellular matrix of adipogenically differentiated mesenchymal stem cells reveals a network of collagen filaments, mostly interwoven by hexagonal structural units

Extracellular matrix (ECM) is the non-cellular component of tissues, which not only provides biological shelter but also takes part in the cellular decisions for diverse functions. Every tissue has an ECM with unique composition and topology that governs the process of determination, differentiation, proliferation, migration and regeneration of cells. Little is known about the structural organization of matrix especially of MSC-derived adipogenic ECM. Here, we particularly focus on the composition and architecture of the fat ECM to understand the cellular behavior on functional bases. Thus, mesenchymal stem cells (MSC) were adipogenically differentiated, then, were transferred to adipogenic propagation medium, whereas they started the release of lipid droplets leaving bare network of ECM. Microarray analysis was performed, to indentify the molecular machinery of matrix. Adipogenesis was verified by Oil Red O staining of lipid droplets and by qPCR of adipogenic marker genes PPARG and FABP4. Antibody staining demonstrated the presence of collagen type I, II and IV filaments, while alkaline phosphatase activity verified the ossified nature of these filaments. In the adipogenic matrix, the hexagonal structures were abundant followed by octagonal structures, whereas they interwoven in a crisscross manner. Regarding molecular machinery of adipogenic ECM, the bioinformatics analysis revealed the upregulated expression of COL4A1, ITGA7, ITGA7, SDC2, ICAM3, ADAMTS9, TIMP4, GPC1, GPC4 and downregulated expression of COL14A1, ADAMTS5, TIMP2, TIMP3, BGN, LAMA3, ITGA2, ITGA4, ITGB1, ITGB8, CLDN11. Moreover, genes associated with integrins, glycoproteins, laminins, fibronectins, cadherins, selectins and linked signaling pathways were found. Knowledge of the interactive-language between cells and matrix could be beneficial for the artificial designing of biomaterials and bioscaffolds.

Transplantation of a mammary stromal cell line into a mammary fat pad: development of the site-specific in vivo analysis system for mammary stromal cells

The interaction between mammary epithelial and stromal tissue is considered to be important in breast tissue development. In this study, we developed a transplantation procedure for the mammary stromal fibroblastic cell line (MSF) to examine its life in vivo. First we established MSF cells which stably expressed lacZ (lacZ/MSF) and had characteristics of mammary stromal cells. The lacZ/MSF cells were then transplanted into a cleared mammary fat pad of syngenic mice with and without mammary primary epithelial organoids. Whole mount X-gal and carmine staining of the transplants revealed that a number of undifferentiated lacZ/MSF cells survived around the mammary epithelial tissue when transplanted with organoids. These results indicate that transplantation of MSF cells into mammary fat pad was accomplished by co-transplantation with primary mammary organoids. Finally, we discuss the application of transplantation procedure for in vivo studies of the mammary stromal tissue development and stromal-epithelial interactions.

Adipocyte derived paracrine mediators of mammary ductal morphogenesis controlled by retinoic acid receptors

We generated a transgenic (Tg)-mouse model expressing a dominant negative-(DN)-RARα, (RARαG303E) under adipocytes-specific promoter to explore the paracrine role of adipocyte retinoic acid receptors (RARs) in mammary morphogenesis. Transgenic adipocytes had reduced level of RARα, β and γ, which coincided with a severely underdeveloped pubertal and mature ductal tree with profoundly decreased epithelial cell proliferation. Transplantation experiments of mammary epithelium and of whole mammary glands implicated a fat-pad dependent paracrine mechanism in the stunted phenotype of the epithelial ductal tree. Co-cultures of primary adipocytes, or in vitro differentiated adipocyte cell line, with mammary epithelium showed that when activated, adipocyte-RARs contribute to generation of secreted proliferative and pro-migratory factors. Gene expression microarrays revealed a large number of genes regulated by adipocyte-RARs. Among them, pleiotrophin (PTN) was identified as the paracrine effectors of epithelial cell migration. Its expression was found to be strongly inhibited by DN-RARα, an inhibition relieved by pharmacological doses of all-trans retinoic acid (atRA) in culture and in vivo. Moreover, adipocyte-PTHR, another atRA responsive gene, was found to be an up-stream regulator of PTN. Overall, these results support the existence of a novel paracrine loop controlled by adipocyte-RAR that regulates the mammary ductal tree morphogenesis.

Involvement of cytoskeleton-associated proteins in the commitment of C3H10T1/2 pluripotent stem cells to adipocyte lineage induced by BMP2/4

The developmental pathway that gives rise to mature adipocytes involves two distinct stages: commitment and terminal differentiation. Although the important proteins/factors contributing to terminal adipocyte differentiation have been well defined, the proteins/factors in the commitment of mesenchymal stem cells to the adipocyte lineage cells have not. In this study, we applied proteomics analysis profiling to characterize differences between uncommitted C3H10T1/2 pluripotent stem cells and those that have been committed to the adipocyte lineage by BMP4 or BMP2 with the goal to identify such proteins/factors and to understand the molecular mechanisms that govern the earliest stages of adipocyte lineage commitment. Eight proteins were found to be up-regulated by BMP2, and 27 proteins were up-regulated by BMP4, whereas five unique proteins were up-regulated at least 10-fold by both BMP2/4, including three cytoskeleton-associated proteins (i.e. lysyl oxidase (LOX), translationally controlled tumor protein 1 (TPT1), and αB-crystallin). Western blotting further confirmed the induction of the expression of these cytoskeleton-associated proteins in the committed C3H10T1/2 induced by BMP2/4. Importantly, knockdown of LOX expression totally prevented the commitment, whereas knockdown of TPT1 and αB-crystallin expression partially inhibited the commitment. Several published reports suggest that cell shape can influence the differentiation of partially committed precursors of adipocytes, osteoblasts, and chondrocytes. We observed a dramatic change of cell shape during the commitment process, and we showed that knockdown of these cytoskeleton-associated proteins prevented the cell shape change and restored F-actin organization into stress fibers and inhibited the commitment to the adipocyte lineage. Our studies indicate that these differentially expressed cytoskeleton-associate proteins might determine the fate of mesenchymal stem cells to commit to the adipocyte lineage through cell shape regulation.

Breast tissue composition and susceptibility to breast cancer

Breast density, as assessed by mammography, reflects breast tissue composition. Breast epithelium and stroma attenuate x-rays more than fat and thus appear light on mammograms while fat appears dark. In this review, we provide an overview of selected areas of current knowledge about the relationship between breast density and susceptibility to breast cancer. We review the evidence that breast density is a risk factor for breast cancer, the histological and other risk factors that are associated with variations in breast density, and the biological plausibility of the associations with risk of breast cancer. We also discuss the potential for improved risk prediction that might be achieved by using alternative breast imaging methods, such as magnetic resonance or ultrasound. After adjustment for other risk factors, breast density is consistently associated with breast cancer risk, more strongly than most other risk factors for this disease, and extensive breast density may account for a substantial fraction of breast cancer. Breast density is associated with risk of all of the proliferative lesions that are thought to be precursors of breast cancer. Studies of twins have shown that breast density is a highly heritable quantitative trait. Associations between breast density and variations in breast histology, risk of proliferative breast lesions, and risk of breast cancer may be the result of exposures of breast tissue to both mitogens and mutagens. Characterization of breast density by mammography has several limitations, and the uses of breast density in risk prediction and breast cancer prevention may be improved by other methods of imaging, such as magnetic resonance or ultrasound tomography.

Establishment of a mammary stromal fibroblastic cell line for in vitro studies in mice of mammary adipocyte differentiation

Mammary stromal adipose tissue remodeling is important for appropriate mammary gland development during pregnancy, lactation, and involution. However, the precise mechanisms underlying mammary stromal adipose tissue remodeling remain unclear. We have established a mammary stromal, fibroblastlike cell line (MSF) from primary mouse mammary culture by introducing a temperature-sensitive simian virus-40 large tumor antigen. Among several hormones related to mammary gland development, hydrocortisone was found to commit MSF cells to a preadipocyte lineage, whereas insulin was found to induce extracellular matrix-dependent adipogenic differentiation of the cells, as assessed by lipid accumulation and marker gene expression. Interestingly, such hormone-induced adipogenic differentiation of MSF cells, but not 3T3-L1 cells, was suppressed by prolactin through its receptor and downstream STAT5. Furthermore, coculture of MSF cells with mammary epithelial HC11 cells and culture in HC11-conditioned medium also suppressed adipogenic differentiation of MSF cells. We have demonstrated that adipogenic differentiation of at least some populations of mammary stromal cells is modulated by lactogenic hormones and humoral factors from epithelial cells, suggesting that the response of these mammary cells may differ from adipocytes at other sites. We believe that the MSF cell line will prove a useful model to elucidate mammary stromal adipose development in vitro as well as represent an important first step toward developing stable adipocyte cell lines that faithfully represent their site of origin.

The clinical implications of MMP-11 and CK-20 expression in human breast cancer

BACKGROUND

Tumor invasiveness and metastasis in cancer progression is manifested by epigenetic abnormality. However, it remains unknown whether transcription regulation of matrix metalloproteinase-11(MMP-11) and cytoskeleton-20 (CK-20) genes for the homoeostasis of epithelial/connective interface that can enhance cell dissemination and invasion may act as alternative mutators to tumor clinicopathology.

METHODS

Paired cancerous and tumor-adjacent normal tissues from 72 breast cancer patients were assayed for the expression of MMP-11 and CK-20 by using real-time RT-PCR. The expression profiles were evaluated for the association with clinicopathological factors.

RESULTS

Breast tumor tissues displayed higher expression levels of MMP-11 and CK-20 than those of the adjacent non-cancerous tissues. Overexpression of either MMP-11 or CK-20 correlated with patients having poorly differentiated tumors (P(MMP-11)=0.01 and P(CK-20)=0.05) and lymph node metastasis (LNM) (P(MMP-11)=0.004 and P(CK-20)=0.001). A synergistic effect between MMP-11 and CK-20 on risk elevation was significant in patients with advanced tumor stage (OR=2.03, 95%CI=1.10-3.77) and LNM (OR=2.83, 95%CI=1.20-4.71). Additionally, patients lacking progesterone receptor exhibited high expression of MMP-11 and CK-20.

CONCLUSION

We demonstrate that MMP-11 and CK-20 are probable prognostic markers whose expression reflects the stages of tumor differentiation and LNM of breast cancer.

Detection of colonic dysplasia in vivo using a targeted heptapeptide and confocal microendoscopy

A combination of targeted probes and new imaging technologies provides a powerful set of tools with the potential to improve the early detection of cancer. To develop a probe for detecting colon cancer, we screened phage display peptide libraries against fresh human colonic adenomas for high-affinity ligands with preferential binding to premalignant tissue. We identified a specific heptapeptide sequence, VRPMPLQ, which we synthesized, conjugated with fluorescein and tested in patients undergoing colonoscopy. We imaged topically administered peptide using a fluorescence confocal microendoscope delivered through the instrument channel of a standard colonoscope. In vivo images were acquired at 12 frames per second with 50-microm working distance and 2.5-microm (transverse) and 20-microm (axial) resolution. The fluorescein-conjugated peptide bound more strongly to dysplastic colonocytes than to adjacent normal cells with 81% sensitivity and 82% specificity. This methodology represents a promising diagnostic imaging approach for the early detection of colorectal cancer and potentially of other epithelial malignancies.

Mammographic density. Potential mechanisms of breast cancer risk associated with mammographic density: hypotheses based on epidemiological evidence

There is now extensive evidence that mammographic density is an independent risk factor for breast cancer that is associated with large relative and attributable risks for the disease. The epidemiology of mammographic density, including the influences of age, parity and menopause, is consistent with it being a marker of susceptibility to breast cancer, in a manner similar to the concept of 'breast tissue age' described by the Pike model. Mammographic density reflects variations in the tissue composition of the breast. It is associated positively with collagen and epithelial and nonepithelial cells, and negatively with fat. Mammographic density is influenced by some hormones and growth factors as well as by several hormonal interventions. It is also associated with urinary levels of a mutagen. Twin studies have shown that most of the variation in mammographic density is accounted for by genetic factors. The hypothesis that we have developed from these observations postulates that the combined effects of cell proliferation (mitogenesis) and genetic damage to proliferating cells by mutagens (mutagenesis) may underlie the increased risk for breast cancer associated with extensive mammographic density. There is clearly a need for improved understanding of the specific factors that are involved in these processes and of the role played by the several breast tissue components that contribute to density. In particular, identification of the genes that are responsible for most of the variance in percentage density (and of their biological functions) is likely to provide insights into the biology of the breast, and may identify potential targets for preventative strategies in breast cancer.

BMP-4 treatment of C3H10T1/2 stem cells blocks expression of MMP-3 and MMP-13

Microarray gene expression profiling was used to identify bone morphogenetic protein-4 (BMP-4) responsive factors involved in late stages of adipocyte commitment in C3H10T1/2 cells. The analysis revealed that the matrix metalloproteinase-3 (MMP-3) gene decreased 100-fold after BMP-4 treatment, and expression of MMP-13 decreased 19.5-fold. Uncommitted C3H10T1/2 cells exhibit dramatic up-regulation of MMP-3 and MMP-13 genes as cells become confluent. Real-time RT-PCR demonstrated that BMP-4 blocks expression of both transcripts. Likewise, a stable committed preadipocyte line derived from C3H10T1/2 cells did not express MMP-3 or MMP-13 at confluence, despite never receiving BMP-4. Active forms of both proteins were detected in media from confluent C3H10T1/2 cells but not in BMP-4 treated cells. Addition of BMP-4 to confluent C3H10T1/2 cells repressed the expression of both genes but did not induce adipocyte differentiation. The findings indicate that BMP-4-induced down-regulation of MMP-3 and MMP-13 is associated with commitment, but is insufficient to induce adipogenesis.

K+ channel KV3.1 associates with OSP/claudin-11 and regulates oligodendrocyte development

K(+) channels are differentially expressed throughout oligodendrocyte (Olg) development. K(V)1 family voltage-sensitive K(+) channels have been implicated in proliferation and migration of Olg progenitor cell (OPC) stage, and inward rectifier K+ channels (K(IR))4.1 are required for OPC differentiation to myelin-forming Olg. In this report we have identified a Shaw family K(+) channel, K(V)3.1, that is involved in proliferation and migration of OPC and axon myelination. Application of anti-K(V)3.1 antibody or knockout of Kv3.1 gene decreased the sustained K(+) current component of OPC by 50% and 75%, respectively. In functional assays block of K(V)3.1-specific currents or knockout of Kv3.1 gene inhibited proliferation and migration of OPC. Adult Kv3.1 gene-knockout mice had decreased diameter of axons and decreased thickness of myelin in optic nerves compared with age-matched wild-type littermates. Additionally, K(V)3.1 was identified as an associated protein of Olg-specific protein (OSP)/claudin-11 via yeast two-hybrid analysis, which was confirmed by coimmunoprecipitation and coimmunohistochemistry. In summary, the K(V)3.1 K(+) current accounts for a significant component of the total K(+) current in cells of the Olg lineage and, in association with OSP/claudin-11, plays a significant role in OPC proliferation and migration and myelination of axons.

Use of three-dimensional basement membrane cultures to model oncogene-induced changes in mammary epithelial morphogenesis

The development of breast carcinomas involves a complex set of phenotypic alterations in breast epithelial cells and the surrounding microenvironment. While traditional transformation assays provide models for investigating certain aspects of the cellular processes associated with tumor initiation and progression, they do not model alterations in tissue architecture that are critically involved in tumor development. In this review, we provide examples of how three-dimensional (3D) cell culture models can be utilized to dissect the pathways involved in the development of mammary epithelial structures and to elucidate the mechanisms responsible for oncogene-induced phenotypic alterations in epithelial behavior and architecture. Many normal mammary epithelial cell lines undergo a stereotypic morphogenetic process when grown in the presence of exogenous matrix proteins. This 3D morphogenesis culminates in the formation of well-organized, polarized spheroids, and/or tubules that are highly reminiscent of normal glandular architecture. In contrast, transformed cell lines isolated from mammary tumors exhibit significant deviations from normal epithelial behavior in 3D culture. We describe the use of 3D models as a method for both reconstructing and deconstructing the cell biological and biochemical events involved in mammary neoplasia.

Triglyceride accumulation and altered composition of triglyceride-associated fatty acids in the skin of tenascin-X-deficient mice

Tenascin-X (TNX) is a member of the tenascin family of glycoproteins of the extracellular matrix. Here, we observed abnormalities in the skin of TNX-deficient mice in comparison with that of wild-type mice. Histological analysis with Oil Red O staining demonstrated that there was considerable accumulation of lipid in the skin of TNX-deficient (TNX-/-) mice. By thin-layer chromatography of total lipids, it was found that the level of triglyceride was significantly increased in TNX-/- mice. The mRNA levels of most of the lipogenic enzyme genes examined were remarkably increased in TNX-/- mice. By gas chromatography-mass spectrometry analysis of triglyceride-associated fatty acids in the skin, saturated fatty acid palmitoic acid was decreased, whereas unsaturated fatty acids palmitoleic acid and oleic acid were increased in TNX-/- mice compared with those in wild-type mice. Conversely, fibroblast cell lines transfected with TNX showed a significant decrease in the amount of triglyceride. An increase in the saturated fatty acid stearic acid and decreases in the unsaturated fatty acids palmitoleic acid, oleic acid and linoleic acid, compared to those in mock-transfected cells were also caused by over-expression of TNX. These results indicate that TNX is involved in the regulation of triglyceride synthesis and the regulation of composition of triglyceride-associated fatty acids.

Angiogenesis in an in vivo model of adipose tissue development

Obesity is associated with an increased risk for cardiovascular disease and cancer. Angiogenesis is a critical component of these pathological processes, and expanding adipose tissue represents one of the few sites of active angiogenesis in the adult. Despite the potential importance of angiogenesis in obesity, little is known about underlying mechanisms. This problem is magnified by the absence of useful quantitative model systems. In this report, we examine the angiogenic process using the 3T3-F442A model of adipose tissue development. In this model, 3T3-F442A preadipocytes are implanted subcutaneously into athymic Balb/c nude mice. We show that these cells develop into highly vascularized fat pads over the next 14-21 days, and that these fat pads are morphologically similar to normal subcutaneous adipose tissue. Histological studies demonstrate that a new microvasculature is evident as early as 5 days after cell implantation, and real-time quantitative RT-PCR analyses show that the expression of endothelial cell markers and adipogenesis markers increase in parallel during fat pad development. Finally, these preliminary studies suggest that the neovasculature originates by sprouting from larger, host-derived blood vessels that run parallel to peripheral nerves and that endothelial progenitor cells play little, if any, role in this process.

Vascular endothelial growth factor C and vascular endothelial growth factor receptor 3 expression in squamous cell carcinomas of the head and neck

BACKGROUND AND METHODS

VEGF proteins and their receptors are involved in tumor vessel neoformation. The third VEGF receptor, VEGFR3 (flt-4) is important during both blood vessel development and lymphatic vessel formation. Because HNSCC preferentially metastasizes to regional lymph nodes, we investigated the expression of VEGFR3 and its ligand VEGF-C in head and neck squamous cell carcinomas by semiquantitative RT-PCR (4 HNSCC cells lines and 6 HNSCC specimens) and by immunohistochemistry (18 HNSCC specimens). VEGFR3 protein expression was confirmed by Western blotting in four HNSCC cell lines and six HNSCC specimens.

RESULTS

Semiquantitative mRNA analysis showed VEGF-C mRNA expression in three (SCC9, SCC25, LFFR) of four HNSCC cell lines and all six HNSCC specimens. VEGFR3 mRNA was found in two HNSCC cell lines (JPPA and SCC25) and only weakly detected in the other two HNSCC cell lines (SCC9 and LFFR). High amounts of VEGFR3 mRNA were shown in all six patients' tumor specimens. VEGFR3 Western blot analysis yielded a distinct band at the predicted size of 210 kD in JPPA and SCC9 and hardly detectable bands in SCC25 and LFFR cell lines. All six HNSCC specimens displayed strong VEGFR3 protein bands. Immunohistochemistry in 18 HNSCC specimens assigned strong to mediate VEGF-C IR and minor VEGFR3 IR to tumor cells and strong VEGF-C and VEGFR3 IR to tumor surrounding vessels. In addition, intense VEGF-C immunostaining was observed on perivascular and mononuclear cells in the tumor surrounding stroma. Subtyping of VEGFR3+ microvascular tumor vessels revealed partially double immunolabeling with CD34 and flk-1, indicating a common origin of blood and lymphatic vessels. The expression of VEGF-C on tumor cells could be correlated with recurrences, and larger primary tumors had more VEGF-C-positive vessels.

CONCLUSIONS

The broad expression of VEGF C and VEGFR3 in HNSCC suggests involvement in tumor lymph angiogenesis and vascular angiogenesis, promoting tumor growth and propagation of cancer cells. This implies that inhibitors of lymph angiogenesis could become effective therapeutic options similar to classical angiogenesis inhibitors.

Prevention of mammary cancer with conjugated linoleic acid: role of the stroma and the epithelium

Conjugated linoleic acid (CLA), found naturally in dairy products and ruminant meats, refers to isomers of octadecadienoic acid with conjugated double bonds. CLA inhibits both DMBA- and NMU-induced rat mammary carcinogenesis, and its antitumor efficacy is similar whether it is fed only during puberty, or continuously during promotion. Pubertal feeding is associated with a reduced proliferation of the epithelial cells within the terminal end buds (TEBs) and lobular epithelium, and results in a decrease in the epithelial density, suggesting a reduction in the carcinogen-sensitive target population. During promotion, CLA feeding induces apoptosis of preneoplastic lesions. The effects of CLA are mediated by a direct action on the epithelium, as well as by an indirect effect through the stroma. CLA is incorporated into the neutral lipids of mammary adipocytes, where it can serve as a local reservoir of CLA. Additionally, CLA induces the adipogenic differentiation of multipotent mammary stromal cells in vitro, and inhibits their development into three-dimensional capillary networks. This suggested that CLA might inhibit angiogenesis in vivo, a hypothesis that was subsequently confirmed. The antiangiogenic effect is mediated, in part, through a CLA-induced decrease in serum VEGF (vascular endothelial growth factor) and mammary gland VEGF and flk-1. Together, the data suggest that CLA may be an excellent candidate for prevention of breast cancer.

Functional microarray analysis of mammary organogenesis reveals a developmental role in adaptive thermogenesis

The use of DNA microarrays to study vertebrate organogenesis presents unique analytical challenges compared with expression profiling of homogeneous cell populations. We have used a general approach that permits the automated, unbiased identification of biologically relevant patterns of gene expression to study murine mammary gland development. Our studies confirm the utility of this approach by demonstrating the ready identification of cellular processes and pathways of known functional importance in mammary development. Additionally, this approach permitted the identification of genetic pathways with unpredicted patterns of developmental regulation, including those involved in angiogenesis, extracellular matrix synthesis, and the beta-oxidation of fatty acids. Surprisingly, our findings demonstrate that the coordinate regulation of genes involved in the beta-oxidation of fatty acids reflects the presence of an abundant, yet previously unrecognized stromal compartment within the mammary gland that is composed of brown adipose tissue. Our data demonstrate that the amount of brown adipose tissue present in the mammary gland is developmentally regulated; that PPARalpha, Ucp1, and genes involved in fatty acid oxidation are spatially and temporally coregulated during development; that the mammary gland plays a functional role in adaptive thermogenesis; and that the transcriptional control of this adaptive response to cold is itself developmentally regulated.

Human lactiferous mammary gland cells produce vascular endothelial growth factor (VEGF) and express the VEGF receptors, Flt-1 AND KDR/Flk-1

Human milk contains a variety of growth factors. Recently, it was reported that vascular endothelial growth factor (VEGF) was one of them. We investigated milk VEGF isoforms, their functions, and VEGF receptors on mammary gland epithelial cells (MEC). The VEGF concentration in human milk was 74.3+/-34.9ng/ml on the first day after delivery, and rapidly decreased in a couple of days to 6.2+/-2.3ng/ml on the fifth day, and matured milk maintained about 4ng/ml. In an MTT assay, human milk accelerated HUVEC proliferation and MV303, a neutralizing antibody of VEGF, blocked 17.3 % of the effect. Immunoprecipitation and Western blotting showed that VEGF121 and VEGF165 were contained in human colostrums, and RT-PCR of human MEC confirmed that VEGF121, VEGF165 and VEGF189 were present. By immunostaining of human breast tissues, RT-PCR of MEC from human colostrum and measurement of the VEGF concentrations of conditioned media of cultured human MEC, it was confirmed that VEGF was produced by MEC. MEC was also expressed VEGF receptors, flt-1 and Flk-1/KDR. These results speculate us that the existence of autocrine or paracrine system within breast tissue via VEGF receptors on MEC and have a role in lactation.

Role of monocytes and macrophages in adult angiogenesis: a light at the tunnel's end

In spite of sustained efforts, there are still gaps in our understanding of angiogenesis as it takes place in vivo. Older observations and a number of recent developments strongly involve the blood mononuclear cell population, collectively known as monocytes (MC), in the normal and pathological adult angiogenesis. An emerging paradigm should eventually incorporate the established biochemical cross talk between MC and their descendents, tissular macrophages (Mph), and the endothelial cells (EC); additionally, it should account for both the intercellular cooperation at the morphological level and the phenotypic overlap between the two cell populations. This focused review puts together the pieces of this puzzle in such a way as to suggest an alternative angiogenic model applicable to adult animals, and particularly to pathological conditions. A working hypothesis is put forward, which is centered on the preformation of capillary lumen as a "tunnel" drilled by penetrating MC/Mph. The tunnels may be colonized in a later stage by sprouts, circulating progenitor endothelial cells (CPEC) or transdifferentiated EC. Thus, MC/Mph are suggested to be included among the targets of therapeutic manipulation of angiogenesis.

Matrix metalloproteinase inhibition impairs adipose tissue development in mice

The effect of galardin, a broad-spectrum matrix metalloproteinase (MMP) inhibitor, was studied in mice kept on a high fat diet (HFD). Five-week-old male wild-type mice were fed the HFD (42% fat) for up to 12 weeks and were daily injected intraperitoneally with the inhibitor (100 mg/kg) or with vehicle. After 12 weeks of the HFD, the body weights of both groups were comparable, but the weight of the isolated subcutaneous (SC) or gonadal (GON) fat deposits was significantly lower in the inhibitor-treated group than in the control group (88 +/- 11 versus 251 +/- 66 mg, respectively, for SC fat [P<0.05]; 90 +/- 24 versus 217 +/- 30 mg, respectively, for GON fat [P<0.02]). The number of adipocytes was somewhat higher and the diameter was somewhat smaller (but not significantly) in adipose tissues of the inhibitor-treated group. Adipose tissue of the inhibitor-treated mice contained more collagen than did that of the vehicle-treated mice (Sirius red-stained area of 42 +/- 2.6% versus 22 +/- 4.4%, respectively, for SC fat [P<0.05]; 21 +/- 5.1% versus 4.7 +/- 0.92%, respectively, for GON fat [P<0.01]); a distinct collagen-rich cap was formed around the inhibitor-treated tissue. In situ zymography with casein- or gelatin-containing gels confirmed a reduced MMP activity in SC and GON adipose tissues of inhibitor-treated mice. Thus, in this model, growth and development of adipose tissue appears to be limited by the formation of a collagen-rich matrix cap around the inhibitor-treated tissue. These data suggest a functional role for MMPs in the development of adipose tissue.

Vascular endothelial growth factor receptor 2 (VEGFR2) expression in squamous cell carcinomas of the head and neck

OBJECTIVES

Vascular endothelial growth factor receptor 2 (VEGFR2; Flk-1 [fetal liver kinase]/KDR [kinase insert domain containing receptor]) has been identified as a high affinity receptor for vascular endothelial growth factor (VEGF) on vascular endothelium. Head and neck squamous cell carcinomas (HNSCC) have already been shown to produce substantial amounts of VEGF. VEGFR2 is supposed to play a major role in tumor-neoangiogenesis.

METHODS

We investigated 24 tumor specimens and 4 HNSCC cultured tumor cell lines for the incidence and distribution of VEGFR2 by immunohistochemistry using monoclonal antibodies (mAbs) and RT-PCR.

RESULTS

Analysis of frozen sections by immunohistochemistry showed that in 90% of tumor specimens VEGFR2-positive cells were found which were associated with vascular endothelium. VEGFR2 was also expressed on tumor cells and vessels, which was confirmed by double immunolabeling of tumor cells with an a-cytokeratin mAb. Furthermore, 2 (JPPA, SCC9) of 4 HNSCC cultured tumor cell lines revealed positive VEGFR2 immunoreactivity. Synthesis of VEGFR2 mRNA on all 4 HNSCC cultured tumor cell lines (JPPA, SCC9, SCC25, and LFFR) and in 6 tumor specimens was confirmed by RT-PCR. In conclusion, our results showed that VEGFR2 is expressed in HNSCCs on tumor cells. VEGFR2 expression is associated with the beginning of vasculogenesis represented by accumulation of VEGFR2-positive cells budding into new vessels ("hot spots"). The focal expression pattern of VEGFR2 on tumor cells suggests an autocrine loop for VEGF in tumor cell growth.

Partial purification and characterization of proteins with growth promoting activities from ovine mammary gland secretions

Developmental regulation of growth promoting activities in mammary secretions of pregnant Awassi ewes was defined, and growth factors contained in these secretions were partially purified and characterised. Mammary secretions from pregnant ewes enhanced fibroblast cell (AKR-2B) and mammary cell (CID-9 cell strain) proliferation to levels comparable to that induced by 10% Foetal calf serum. Major milk proteins in mammary secretions collected from pregnant ewes one month prior to lambing up to one week after lambing, were resolved by SDS-PAGE, while gelatinases were resolved by zymography. Gelatinase activity was noted prior to P134 and decreased thereafter to reach a minimum during lactation. This decrease was concomitant with the onset of casein production. It is during this critical developmental period that highest growth promoting activity in mammary secretions was detected. Secretions with highest growth promoting activity were fractionated by ion exchange and gel filtration chromatography. Two heat-resistant, trypsin/chymotrypsin sensitive, growth-promoting activities were characterised. The first, designated ovine mammary derived growth factor-1 (oMDGF-1), had around a 30 kDa molecular weight and eluted at 0.65 M NaCl gradient on cation ion exchange chromatography. The second, oMDGF-2, eluted under gel filtration conditions at a molecular weight of 50 kDa and 150 kDa. oMDGF-1 induced changes in Connexin 43, but not in beta-casein mRNA expression by CID-9 mammary cells. In conclusion, growth factor activities in ewe mammary secretions peak during gestation at a period that overlaps maximal gelatinase expression and precedes milk protein synthesis. The factors modulate mammary cell function and may play a role in mammary gland development.

Adipocyte produces matrix metalloproteinases 2 and 9: involvement in adipose differentiation

Adipocyte hypertrophy and hyperplasia together with angiogenesis contribute to the growth of the fat mass. Because changes in the extracellular matrix (ECM) components are often associated with such cellular remodeling, we studied the adipocyte expression of the matrix metalloproteinases (MMPs) 2 and 9, two key enzymes involved in the modulation of ECM. The present study provides the first evidence that human adipose tissue produces and secretes MMP-2 and -9 as shown by gelatin zymography analysis performed on media conditioned by human subcutaneous adipose tissue and human preadipocytes in primary cultures and by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis on transcripts from mature human adipocytes. The further characterization performed on the murine 3T3F442A preadipocyte cell line demonstrates that MMP expression, assessed by RT-PCR and Western blot analysis, as well as activity, assessed by gelatin zymography analysis, increased during the adipocyte differentiation, whereas the expression of tissue inhibitor metalloproteinases 1 and 2 were abolished or not affected, respectively. Finally, preadipocyte treatment with MMP inhibitors such as batimastat and captopril, as well as neutralizing antibodies, markedly decreased adipocyte differentiation as demonstrated by the inhibition in the appearance of lipogenic (triglycerides) and lipolytic (glycerol release and hormone-sensitive lipase expression) markers. These data suggest that MMP-2 and -9 could be important key regulators of adipocyte differentiation. Thus, the adipocyte-derived MMPs might represent a new target for the inhibition of adipose tissue growth.

Transcriptional regulation of vascular endothelial growth factor expression in epithelial and stromal cells during mouse mammary gland development

Accompanying changes in the development and function of the mammary gland is the establishment of a vascular network of critical importance for lactogenesis and tumorigenesis. A potent angiogenic and permeability factor that regulates vascular development in association with epithelial-stromal interactions is vascular endothelial growth factor (VEGF). Analysis of VEGF transcription by RT-PCR revealed mRNA for all three VEGF isoforms (VEGF120, 164, 188) within the mammary gland of nulliparous females. During pregnancy the level of VEGF188 declined and became undetectable during lactation in association with the increased abundance of VEGF120 and VEGF164 mRNAS: All three isoforms were expressed at consistent levels within the cleared mammary fat pad throughout development. Furthermore, the presence of VEGF188 mRNA in omental adipose tissue at various stages established that VEGF188 is expressed specifically in adipose tissue within the mammary gland. Using 3T3-L1 preadipocytes it was demonstrated that VEGF188 mRNA transcription occurs as a late event during lipogenesis distinct from earlier induction of VEGF120 and VEGF164 mRNA during differentiation. In contrast, HC11 mammary epithelial cells only expressed mRNA for VEGF120 and VEGF164. Localization of VEGF mRNA and protein revealed that VEGF is expressed in stromal cells of the mammary gland in nulliparous females and then undergoes a transition to epithelial expression during lactation. By contrast, mRNA for the VEGF receptors, Flk-1 and Flt-1, localized to stromal cells within the mammary fat pad during virgin and gestational development and was expressed in the interstitial tissue basal to epithelial cells during lactation. Taken together, these results support the conclusion that VEGF is differentially transcribed by specific cell types within the mammary gland, and that under hormonal regulation it functions in an autocrine/paracrine manner.

Identification of receptor ligands by screening phage-display peptide libraries ex vivo on microdissected kidney tubules

A novel method to identify receptor ligands for defined renal tubular segments has been developed. Ex vivo screening of phage-display peptide libraries on isolated intact rat proximal convoluted tubules (PCT) and cortical collecting ducts (CCD) allowed the direct access of phage to the basolateral surface of tubular epithelial cells. Two distinct peptide motifs were selected for CCD and PCT, indicating differential expression of some membrane receptors on the basolateral surface of defined kidney tubule segments. Using the linear peptide motif ELRGD(R/M)AX(W/L), recovered from freshly isolated rat CCD, mediated 16-fold selectivity of phage binding to CCD compared with PCT. Binding to CCD was 39-fold higher than that of a random control phage. Binding and subsequent internalization of phage, most likely by an integrin-mediated endocytosis pathway, was abolished by the addition of the corresponding synthetic peptide. Furthermore, the results demonstrate that presentation and flanking amino acids determine the specific binding properties of RGD ligands to their putative integrin receptors. The results emphasize the need of a native cell system for the identification of renal epithelial cell surface ligands. Such ligands are of potential relevance for the analysis of interactions between extracellular matrix and kidney tubules or for the development of improved vectors for kidney-specific drug delivery or gene transfer.

Cytochemical studies on the fibroblast-preadipocyte relationships in cultured fibroblast cell lines

The theoretical basis of adipogenesis has always been a matter of debate. One concept suggests that all types of adipocytes are derived from undifferentiated connective tissue cells, whereas another concept suggests that adipocytes develop from specialized cells only that are able to accumulate fat. Many conflicting data have been published with respect to the transition of fibroblasts into preadipocytes. For example, this transition has been declared as impossible for dermal and perimysial fibroblasts. The present study analysed spontaneous accumulation of fat in various types of fibroblasts from different origin (retroocular, skin, NIH/3T3, and L929). It was found that intense Oil Red O-positive triglyceride-containing droplets accumulated in practically all types of fibroblasts provided that the cells were cultured on glass surface. When the cells were cultured on plastic surfaces, lipid staining was inhibited in a variable manner: inhibition was virtually complete in skin fibroblasts, whereas in other types of fibroblasts, inhibition was only partial. It is concluded that all types of fibroblasts can accumulate fat spontaneously, and thus can be considered as preadipocytes. Therefore, interpretations of data obtained with cultures of fibroblasts with respect to adipogenesis have to be reconsidered.

Pharmacological study of signal transduction during stimulation of prothoracic glands from Manduca sexta

Cytosolic free calcium, [Ca(2+)](i), measured in individual prothoracic gland cells of Manduca sexta with Fura-2 was increased by prothoracicotropic hormone, PTTH, and by mastoparan, a wasp venom peptide, activating G proteins. The effect on [Ca(2+)](i) of mastoparan and of PTTH was inhibited by cadmium and the antagonist of T-type calcium channels, amiloride, and not influenced by the L-type calcium channel blocker nitrendipine, suggesting that the same or similar plasma membrane channels are involved in the action of mastoparan and of PTTH. Pertussis toxin prevented the mastoparan-induced increase of [Ca(2+)](i), whereas the effect of PTTH is not influenced by pertussis toxin. Intracellular addition of GDP-beta-S failed to inhibit the PTTH-stimulated increase in [Ca(2+)](i) suggesting that G proteins are not involved in the stimulatory mechanism of PTTH.

Changes in ErbB2 (her-2/neu), ErbB3, and ErbB4 during growth, differentiation, and apoptosis of normal rat mammary epithelial cells

Studies were undertaken to examine the natural role of ErbB2, ErbB3, and ErbB4 during the development of normal rat mammary epithelial cells (MECs) in vivo and in vitro. Immunohistochemical analysis demonstrated that mammary gland terminal end buds expressed abundant ErbB2 and ErbB4 but limited ErbB3 in pubescent rats, whereas luminal epithelial cells in nulliparous rats expressed ErbB2, ErbB3, and/or ErbB4. During pregnancy, ductal epithelial cells and stromal cells expressed abundant ErbB3 but limited ErbB2. Although ErbB2 and ErbB3 were downregulated throughout lactation, both receptors were re-expressed during involution. In contrast, ErbB4 was downregulated throughout pregnancy, lactation, and involution. Immunoblotting and immunoprecipitation studies confirmed the developmental expression of ErbB2 and ErbB3 in the mammary gland and the co-localization of distinct ErbB receptors in the mammary gland of nulliparous rats. In agreement with our in vivo findings, primary culture studies demonstrated that ErbB2 and ErbB3 were expressed in functionally immature, terminally differentiated and apoptotic MECs, and downregulated in functionally differentiated MECs. ErbB receptor signaling was required for epithelial cell growth, functional differentiation, and morphogenesis of immature MECs, and the survival of terminally differentiated MECs. Finally, ErbB4 expression did not interfere with functional differentiation and apoptosis of normal MECs.

Adipocyte-epithelial interactions regulate the in vitro development of normal mammary epithelial cells

Mammary epithelial organoids (MEO), isolated from pubescent rats, were cultured within a reconstituted basement membrane in transwell inserts, in the presence or absence of mature mammary adipocytes in the lower well. This system allowed for free medium exchange between the two compartments, without direct cell-to-cell contact. When cultured in serum-free medium supplemented with insulin, prolactin, hydrocortisone, progesterone, and various epidermal growth factor (EGF) concentrations, mammary adipocytes did not affect epithelial cell growth, but enhanced epithelial differentiation. Casein and lipid accumulations were monitored as indicators of functional differentiation of MEO. Mammary adipocytes significantly enhanced casein and lipid accumulation within the MEO, independently of EGF concentration. Furthermore, adipocytes induced MEO to preferentially undergo alveolar morphogenesis, inhibited squamous outgrowth, and increased lumen size. These findings demonstrate that morphological and functional differentiation of mammary epithelial cells is profoundly enhanced by the adipose stroma and that these effects are mediated by diffusible paracrine factors. This new model can be exploited in future studies to define the mechanisms whereby hormones and growth factors regulate mammary gland development and carcinogenesis. Moreover, it could complement in vivo reconstitution/transplantation studies, which are currently employed to evaluate the role of specific gene deletions in the regulation of mammary development.