Stromal changes in invasive breast carcinoma: an ultrastructural study

Computer-assisted quantification of tumor-associated collagen signatures to improve the prognosis prediction of breast cancer

BACKGROUND

Collagen fibers play an important role in tumor initiation, progression, and invasion. Our previous research has already shown that large-scale tumor-associated collagen signatures (TACS) are powerful prognostic biomarkers independent of clinicopathological factors in invasive breast cancer. However, they are observed on a macroscale and are more suitable for identifying high-risk patients. It is necessary to investigate the effect of the corresponding microscopic features of TACS so as to more accurately and comprehensively predict the prognosis of breast cancer patients.

METHODS

In this retrospective and multicenter study, we included 942 invasive breast cancer patients in both a training cohort (n = 355) and an internal validation cohort (n = 334) from one clinical center and in an external validation cohort (n = 253) from a different clinical center. TACS corresponding microscopic features (TCMFs) were firstly extracted from multiphoton images for each patient, and then least absolute shrinkage and selection operator (LASSO) regression was applied to select the most robust features to build a TCMF-score. Finally, the Cox proportional hazard regression analysis was used to evaluate the association of TCMF-score with disease-free survival (DFS).

RESULTS

TCMF-score is significantly associated with DFS in univariate Cox proportional hazard regression analysis. After adjusting for clinical variables by multivariate Cox regression analysis, the TCMF-score remains an independent prognostic indicator. Remarkably, the TCMF model performs better than the clinical (CLI) model in the three cohorts and is particularly outstanding in the ER-positive and lower-risk subgroups. By contrast, the TACS model is more suitable for the ER-negative and higher-risk subgroups. When the TACS and TCMF are combined, they could complement each other and perform well in all patients. As expected, the full model (CLI+TCMF+TACS) achieves the best performance (AUC 0.905, [0.873-0.938]; 0.896, [0.860-0.931]; 0.882, [0.840-0.925] in the three cohorts).

CONCLUSION

These results demonstrate that the TCMF-score is an independent prognostic factor for breast cancer, and the increased prognostic performance (TCMF+TACS-score) may help us develop more appropriate treatment protocols.

Influence of Fibroblasts on Mammary Gland Development, Breast Cancer Microenvironment Remodeling, and Cancer Cell Dissemination

The stromal microenvironment regulates mammary gland development and tumorigenesis. In normal mammary glands, the stromal microenvironment encompasses the ducts and contains fibroblasts, the main regulators of branching morphogenesis. Understanding the way fibroblast signaling pathways regulate mammary gland development may offer insights into the mechanisms of breast cancer (BC) biology. In fact, the unregulated mammary fibroblast signaling pathways, associated with alterations in extracellular matrix (ECM) remodeling and branching morphogenesis, drive breast cancer microenvironment (BCM) remodeling and cancer growth. The BCM comprises a very heterogeneous tissue containing non-cancer stromal cells, namely, breast cancer-associated fibroblasts (BCAFs), which represent most of the tumor mass. Moreover, the different components of the BCM highly interact with cancer cells, thereby generating a tightly intertwined network. In particular, BC cells activate recruited normal fibroblasts in BCAFs, which, in turn, promote BCM remodeling and metastasis. Thus, comparing the roles of normal fibroblasts and BCAFs in the physiological and metastatic processes, could provide a deeper understanding of the signaling pathways regulating BC dissemination. Here, we review the latest literature describing the structure of the mammary gland and the BCM and summarize the influence of epithelial-mesenchymal transition (EpMT) and autophagy in BC dissemination. Finally, we discuss the roles of fibroblasts and BCAFs in mammary gland development and BCM remodeling, respectively.

Galectin-3 Regulates the Expression of Tumor Glycosaminoglycans and Increases the Metastatic Potential of Breast Cancer

Galectin-3 (Gal-3) is a multifunctional β-galactoside-binding lectin that once synthesized is expressed in the nucleus, cytoplasm, cell surface, and extracellular environment. Gal-3 plays an important role in breast cancer tumors due to its ability to promote interactions between cell-cell and cell-extracellular matrix (ECM) elements, increasing tumor survival and metastatic dissemination. Still, the mechanism by which Gal-3 interferes with tumor cell migration and metastasis formation is complex and not fully understood. Here, we showed that Gal-3 knockdown increased the migration ability of 4T1 murine breast cancer cells in vitro. Using the 4T1 orthotopic breast cancer spontaneous metastasis mouse model, we demonstrated that 4T1-derived tumors were significantly larger in the presence of Gal-3 (scramble) in comparison with Gal-3 knockdown 4T1-derived tumors. Nevertheless, Gal-3 knockdown 4T1 cells were outnumbered in the bone marrow in comparison with scramble 4T1 cells. Finally, we reported here a decrease in the content of cell-surface syndecan-1 and an increase in the levels of chondroitin sulfate proteoglycans such as versican in Gal-3 knockdown 4T1 cells both in vitro and in vivo. Overall, our findings establish that Gal-3 downregulation during breast cancer progression regulates cell-associated and tumor microenvironment glycosaminoglycans (GAGs)/proteoglycans (PG), thus enhancing the metastatic potential of tumor cells.

Mammographic density: intersection of advocacy, science, and clinical practice

Purpose

Here we aim to review the association between mammographic density, collagen structure and breast cancer risk.

Findings

While mammographic density is a strong predictor of breast cancer risk in populations, studies by Boyd show that mammographic density does not predict breast cancer risk in individuals. Mammographic density is affected by age, parity, menopausal status, race/ethnicity, and body mass index (BMI).New studies normalize mammographic density to BMI may provide a more accurate way to compare mammographic density in women of diverse race and ethnicity. Preclinical and tissue-based studies have investigated the role collagen composition and structure in predicting breast cancer risk. There is emerging evidence that collagen structure may activate signaling pathways associated with aggressive breast cancer biology.

Summary

Measurement of film mammographic density does not adequately capture the complex signaling that occurs in women with at-risk collagen. New ways to measure at-risk collagen potentially can provide a more accurate view of risk.

Targeting Cancer Stem Cells-A Renewed Therapeutic Paradigm

Metastasis is often accompanied by radio- and chemotherapeutic resistance to anticancer treatments and is the major cause of death in cancer patients. Better understanding of how cancer cells circumvent therapeutic insults and how disseminated cancer clones generate life-threatening metastases would therefore be paramount to the development of effective therapeutic approaches for clinical management of malignant disease. Mounting reports over the past two decades have provided evidence for the existence of a minor population of highly malignant cells within liquid and solid tumors, which are capable of self-renewing and of regenerating secondary growths with the heterogeneity of the primary tumors from which they derive. These cells, called tumor-initiating cells or cancer stem cells (CSCs) exhibit increased resistance to standard radio- and chemotherapies and appear to have mechanisms that enable them to evade immune surveillance. CSCs are therefore considered to be responsible for systemic residual disease after cancer therapy, as well as for disease relapse. How CSCs develop, the nature of the interactions they establish with their microenvironment, their phenotypic and functional characteristics, as well as their molecular dependencies have all taken center stage in cancer therapy. Indeed, improved understanding of CSC biology is critical to the development of important CSC-based anti-neoplastic approaches that have the potential to radically improve cancer management. Here, we summarize some of the most pertinent elements regarding CSC development and properties, and highlight some of the clinical modalities in current development as anti-CSC therapeutics.

Mesenchymal Stem/Stromal Cells in Stromal Evolution and Cancer Progression

The study of cancer biology has mainly focused on malignant epithelial cancer cells, although tumors also contain a stromal compartment, which is composed of stem cells, tumor-associated fibroblasts (TAFs), endothelial cells, immune cells, adipocytes, cytokines, and various types of macromolecules comprising the extracellular matrix (ECM). The tumor stroma develops gradually in response to the needs of epithelial cancer cells during malignant progression initiating from increased local vascular permeability and ending to remodeling of desmoplastic loosely vascularized stromal ECM. The constant bidirectional interaction of epithelial cancer cells with the surrounding microenvironment allows damaged stromal cell usage as a source of nutrients for cancer cells, maintains the stroma renewal thus resembling a wound that does not heal, and affects the characteristics of tumor mesenchymal stem/stromal cells (MSCs). Although MSCs have been shown to coordinate tumor cell growth, dormancy, migration, invasion, metastasis, and drug resistance, recently they have been successfully used in treatment of hematopoietic malignancies to enhance the effect of total body irradiation-hematopoietic stem cell transplantation therapy. Hence, targeting the stromal elements in combination with conventional chemotherapeutics and usage of MSCs to attenuate graft-versus-host disease may offer new strategies to overcome cancer treatment failure and relapse of the disease.

Modeling prolactin actions in breast cancer in vivo: insights from the NRL-PRL mouse

Elevated exposure to prolactin (PRL) is epidemiologically associated with an increased risk of aggressive ER+ breast cancer. To understand the underlying mechanisms and crosstalk with other oncogenic factors, we developed the NRL-PRL mouse. In this model, mammary expression of a rat prolactin transgene raises local exposure to PRL without altering estrous cycling. Nulliparous females develop metastatic, histotypically diverse mammary carcinomas independent from ovarian steroids, and most are ER+. These characteristics resemble the human clinical disease, facilitating study of tumorigenesis, and identification of novel preventive and therapeutic approaches.

Preferential, enhanced breast cancer cell migration on biomimetic electrospun nanofiber 'cell highways'

BACKGROUND

Aggressive metastatic breast cancer cells seemingly evade surgical resection and current therapies, leading to colonization in distant organs and tissues and poor patient prognosis. Therefore, high-throughput in vitro tools allowing rapid, accurate, and novel anti-metastatic drug screening are grossly overdue. Conversely, aligned nanofiber constitutes a prominent component of the late-stage breast tumor margin extracellular matrix. This parallel suggests that the use of a synthetic ECM in the form of a nanoscale model could provide a convenient means of testing the migration potentials of cancer cells to achieve a long-term goal of providing clinicians an in vitro platform technology to test the efficacy of novel experimental anti-metastatic compounds.

METHODS

Electrospinning produces highly aligned, cell-adhesive nanofiber matrices by applying a strong electric field to a polymer-containing solution. The resulting fibrous microstructure and morphology closely resembles in vivo tumor microenvironments suggesting their use in analysis of migratory potentials of metastatic cancer cells. Additionally, a novel interface with a gel-based delivery system creates CXCL12 chemotactic gradients to enhance CXCR4-expressing cell migration.

RESULTS

Cellular dispersions of MCF-10A normal mammary epithelial cells or human breast cancer cells (MCF-7 and MDA-MB-231) seeded on randomly-oriented nanofiber exhibited no significant differences in total or net distance traveled as a result of the underlying topography. Cells traveled ~2-5 fold greater distances on aligned fiber. Highly-sensitive MDA-MB-231 cells displayed an 82% increase in net distance traversed in the presence of a CXCL12 gradient. In contrast, MCF-7 cells exhibited only 31% increase and MCF-10A cells showed no statistical difference versus control or vehicle conditions. MCF-10A cells displayed little sensitivity to CXCL12 gradients, while MCF-7 cells displayed early sensitivity when CXCL12 concentrations were higher. MDA-MB-231 cells displayed low relative expression levels of CXCR4, but high sensitivity resulting in 55-fold increase at late time points due to CXCL12 gradient dissipation.

CONCLUSIONS

This model could create clinical impact as an in vitro diagnostic tool for rapid assessment of tumor needle biopsies to confirm metastatic tumors, their invasiveness, and allow high-throughput drug screening providing rapid development of personalized therapies.

Hypoxia and the extracellular matrix: drivers of tumour metastasis

Of the deaths attributed to cancer, 90% are due to metastasis, and treatments that prevent or cure metastasis remain elusive. Emerging data indicate that hypoxia and the extracellular matrix (ECM) might have crucial roles in metastasis. During tumour evolution, changes in the composition and the overall content of the ECM reflect both its biophysical and biological properties and these strongly influence tumour and stromal cell properties, such as proliferation and motility. Originally thought of as independent contributors to metastatic spread, recent studies have established a direct link between hypoxia and the composition and the organization of the ECM, which suggests a new model in which multiple microenvironmental signals might converge to synergistically influence metastatic outcome.

Why the stroma matters in breast cancer: insights into breast cancer patient outcomes through the examination of stromal biomarkers

Survival and recurrence rates in breast cancer are variable for common diagnoses, and therefore the biological underpinnings of the disease that determine those outcomes are yet to be fully understood. As a result, translational medicine is one of the fastest growing arenas of study in tumor biology. With advancements in genetic and imaging techniques, archived biopsies can be examined for purposes other than diagnosis. There is a great deal of evidence that points to the stroma as the major regulator of tumor progression following the initial stages of tumor formation, and the stroma may also contribute to risk factors determining tumor formation. Therefore, aspects of stromal biology are well-suited to be a focus for studies of patient outcome, where statistical differences in survival among patients provide evidence as to whether that stromal component is a signpost for tumor progression. In this review we summarize the latest research done where breast cancer patient survival was correlated with aspects of stromal biology, which have been put into four categories: reorganization of the extracellular matrix (ECM) to promote invasion, changes in the expression of stromal cell types, changes in stromal gene expression, and changes in cell biology signaling cascades to and from the stroma.

Mechanobiology of tumor invasion: engineering meets oncology

The physical sciences and engineering have introduced novel perspectives into the study of cancer through model systems, tools, and metrics that enable integration of basic science observations with clinical data. These methods have contributed to the identification of several overarching mechanisms that drive processes during cancer progression including tumor growth, angiogenesis, and metastasis. During tumor cell invasion - the first clinically observable step of metastasis - cells demonstrate diverse and evolving physical phenotypes that cannot typically be defined by any single molecular mechanism, and mechanobiology has been used to study the physical cell behaviors that comprise the "invasive phenotype". In this review, we discuss the continually evolving pathological characterization and in vitro mechanobiological characterization of tumor invasion, with emphasis on emerging physical biology and mechanobiology strategies that have contributed to a more robust mechanistic understanding of tumor cell invasion. These physical approaches may ultimately help to better predict and identify tumor metastasis.

Usefulness of diffusion-weighted imaging of breast tumors: quantitative and visual assessment

PURPOSE

We evaluated the usefulness of quantitative and visual assessment of diffusion-weighted imaging (DWI) of breast tumors to distinguish malignant from benign tumors.

MATERIALS AND METHODS

The DWI findings of 106 breast lesions (15 benign, 91 malignant) were retrospectively analyzed. The mean apparent diffusion coefficient (ADC) value for each lesion was calculated using b values of 250, 500, 750, and 1000 s/mm(2) as a quantitative assessment. We visually evaluated the signal intensity of each breast lesion on the basis of a spinal signal intensity in DWI (b = 1000 s/mm(2)) and compared the mean ADC values using a threshold mean ADC +1.65 × standard deviation (SD) for malignant and benign breast lesions. Obviously strong signal intensity of the lesion relative to that of the spinal cord on DWI signifies malignancy.

RESULTS

The mean ADC value for benign lesions (1.50 ± 0.38 × 10(-3) mm(2)/s) was significantly higher than that for malignant lesions (0.98 ± 0.19 × 10(-3) mm(2)/s), with 94.5% sensitivity, 80% specificity, and 92.5% accuracy. Sensitivity for visual assessment was 91.5%, specificity was 33.3%, and total accuracy was 82.5%.

CONCLUSION

ADC values, but not visual assessment, may be useful for differentiating benign and malignant breast tumors.

Aligned collagen is a prognostic signature for survival in human breast carcinoma

Evidence for the potent influence of stromal organization and function on invasion and metastasis of breast tumors is ever growing. We have performed a rigorous examination of the relationship of a tumor-associated collagen signature-3 (TACS-3) to the long-term survival rate of human patients. TACS-3 is characterized by bundles of straightened and aligned collagen fibers that are oriented perpendicular to the tumor boundary. An evaluation of TACS-3 was performed in biopsied tissue sections from 196 patients by second harmonic generation imaging of the backscattered signal generated by collagen. Univariate analysis of a Cox proportional hazard model demonstrated that the presence of TACS-3 was associated with poor disease-specific and disease-free survival, resulting in hazard ratios between 3.0 and 3.9. Furthermore, TACS-3 was confirmed to be an independent prognostic indicator regardless of tumor grade and size, estrogen or progesterone receptor status, human epidermal growth factor receptor-2 status, node status, and tumor subtype. Interestingly, TACS-3 was positively correlated to expression of stromal syndecan-1, a receptor for several extracellular matrix proteins including collagens. Because of the strong statistical evidence for poor survival in patients with TACS, and because the assessment can be performed in routine histopathological samples imaged via second harmonic generation or using picrosirius, we propose that quantifying collagen alignment is a viable, novel paradigm for the prediction of human breast cancer survival.

More Than Structural Cells, Fibroblasts Create and Orchestrate the Tumor Microenvironment

The tumor microenvironment comprises many cell types including infiltrating immune cells such as lymphocytes, endothelial cells and a complex stroma consisting mainly of fibroblasts. Fibroblasts are heterogeneous and consist of Thy-1+ and Thy-1- subsets that define different biosynthetic and differentiation potential. They produce mediators linked to carcinogenesis and metastasis, including Cox-2 and PGE2, both of which are also increased in most cancers. This review will highlight the emerging role of the complex fibroblastic stroma in establishing a microenvironment supporting malignant transformation, tumor growth and attenuation of host anti-tumor immune responses.

Extracellular matrix signature identifies breast cancer subgroups with different clinical outcome

Prediction of the clinical outcome of breast cancer is multi-faceted and challenging. There is growing evidence that the complexity of the tumour micro-environment, consisting of several cell types and a complex mixture of proteins, plays an important role in development, progression, and response to therapy. In the current study, we investigated whether invasive breast tumours can be classified on the basis of the expression of extracellular matrix (ECM) components and whether such classification is representative of different clinical outcomes. We first examined the matrix composition of 28 primary breast carcinomas by morphology and gene expression profiling using 22K oligonucleotide Agilent microarrays. Hierarchical clustering of the gene expression profile of 278 ECM-related genes derived from the literature divided the tumours into four main groups (ECM1-4). A set of selected differentially expressed genes was validated by immunohistochemistry. The robustness of the ECM classification was confirmed by studying the four ECM groups in a previously published gene expression data set of 114 early-stage primary breast carcinomas profiled using cDNA arrays. Univariate survival analysis showed significant differences in clinical outcome among the various ECM subclasses. One set of tumours, designated ECM4, had a favourable outcome and was defined by the overexpression of a set of protease inhibitors belonging to the serpin family, while tumours with an ECM1 signature had a poorer prognosis and showed high expression of integrins and metallopeptidases, and low expression of several laminin chains. Furthermore, we identified three surrogate markers of ECM1 tumours: MARCO, PUNC, and SPARC, whose expression levels were associated with breast cancer survival and risk of recurrence. Our findings suggest that primary breast tumours can be classified based upon ECM composition and that this classification provides relevant information on the biology of breast carcinomas, further supporting the hypothesis that clinical outcome is strongly related to stromal characteristics.

"Stromatogenesis" and tumor progression

"Stromatogenesis" is the formation of new stroma occurring, in parallel with the neoplastic process, at sites of active tumor invasion, i.e., at the free surface of a developing exophytic tumor, at the invading tumor front of an advancing endophytic tumor, and at sites of tumor metastasis, wherein the newly formed stroma disrupts the continuity of normal structures, cleaving paths for the invading tumor cells. Stroma is also present at the heart of the tumor, but only as a secondary event following tumor advancement and subsequent incorporation of its periphery into inner tumor areas. The new stroma, composed of stromal cells and extracellular matrix (ECM), is loose and edematous at the expanding tumor fronts, and rather dense in central tumor areas and sites of tumor metastasis. The stromal cells facing tumor invasion are intensely proliferating (high MIB-1 index) spindle-shaped cells, alpha-smooth muscle actin positive, and loaded with thymidine phosphorylase (TP) and SPARC (secreted protein acidic and rich in cysteine). The associated ECM is rich in collagen III, SPARC, and new blood vessels (CD31) but is depleted of collagen I and fibronectin. These constitutional changes render stromatogenesis amenable to tumor cell invasion and are, in cases of incipient neoplasia, a prospective criterion of early stromal invasion. Other stromal cell or ECM constituents, such as the lactate dehydrogenase-5 (LDH-5), the acidic fibroblast growth factor (aFGF), the basic FGF (bFGF), and the collagens II and IV, remain unchanged, and others are negative: myosin, desmin, S-100 protein and epidermal growth factor receptor (EGFR). The mechanism of stromatogenesis is obscure but is probably stimulated by specific stromatogenic growth factors, released by neoplastic and inflammatory cells. It appears that the process is neither neoplastic nor reactive, but rather is a, hereto unexplained, phenomenon of host's complicity in tumor progression.

Three-dimensional in vitro cocultivation of lung carcinoma cells with human bronchial organ culture as a model for bronchial carcinoma

We describe the development of a three-dimensional in vitro organ culture model for bronchial carcinoma using bronchial mucosa organ cultures and three different human non-small cell lung cancer cell lines. During precultivation, bronchial fragments obtained as biopsies during routine bronchoscopy had regenerated a complete epithelial covering with a well-preserved organotypic architecture around a nucleus consisting of connective tissue. To create cocultures, different types of confrontation between tumor cells and organ cultures were applied. Histologic light microscopy and scanning electron microscopy were used in analysis. When tumor cells were confronted with completely epithelialized organ cultures, they showed a low incidence of attachment. When organ cultures were wounded before confrontation, tumor cells always attached to the wounded side and showed a progressive invasion into the stromal tissue. Measurements of the penetration depth of tumor cells into the organ cultures after different incubation times permitted the quantitative evaluation of invasion. Histologic studies revealed well-differentiated normal epithelium in spite of long culture periods. Histologic features of the tumors were those of an invasive undifferentiated carcinoma and showed marked similarities to the situation in vivo. The coculture model permits internal controls because it contains both normal human epithelium and human tumor cells in the same organotypic culture. Therefore it offers opportunities for various in vitro investigations on therapeutic and diagnostic modalities of lung cancer, as indicated in this paper by an example of photodynamic procedures with 5-aminolevulinic acid.

Benign myxoid hepatocellular tumor: a variant of liver cell adenoma

A case of myxoid hepatocellular adenoma in the non-cirrhotic liver of a 26-year-old man is described. Grossly, the tumor was well circumscribed, rounded and measured 16 cm in diameter. Histologically, the tumor was characterized by nests and strands of polygonal cells embedded in a myxoid extracellular matrix. Electron microscopy confirmed the hepatocellular nature of the neoplastic cells. The patient is alive and well, without evidence of disease, 2 years after a local excision.

Assessment of invasion in breast lesions using antibodies to basement membrane components and myoepithelial cells

This paper describes immunostaining of consecutive sections from 15 cases of fibrocystic change of the breast (including 2 examples of intraductal papilloma), 4 ductal carcinomas-in-situ and 17 invasive carcinomas (4 tubular, 1 papillary, 2 lobular and 10 infiltrating ductal, NOS) with antisera to components of the basement membrane (BM), type IV collagen and laminin, and with the muscle antibodies actin and muscle-specific actin. A simple digestion technique was developed to improve the clarity of BM staining with these antibodies. The BM stains facilitated identification of small invasive foci through breaks in the BM in 2 of the cases which had been reported as pure intraductal carcinoma. Tubular carcinomas were surrounded by abnormal, fragmented, and focally discontinuous BM, a feature which could be used to distinguish this well-differentiated breast carcinoma sub-type from sclerosing adenosis, in which individual acini were invariably surrounded by a continuous BM. BM staining emphasized the fibrovascular core of intraductal papillomas, whereas the BM layer was absent in intraductal, cytologically malignant, papillary projections. Similarly, myoepithelial cells, stained with antisera to muscle actins, were identified in a continuous layer surrounding benign epithelial proliferations. These immunohistochemical staining techniques may thus assist the diagnostic histopathologist in differentiating between benign epithelial proliferations of the breast and well-differentiated invasive breast carcinoma, and in identifying foci of microinvasive carcinoma.

Attenuated cells in breast stroma: the missing lymphatic system of the breast

The breast stroma, in association with normal and neoplastic epithelium, is shown to contain cells of similar ultrastructure to the fine lymphatic vessels and sinusoids described in detail in the literature on other organs. As in other organs, the lumen of these structures is in continuity with the tissue spaces, allowing a free flow of lymph and its content, fluid and cells, from the tissues to the drainage system. The lymphatic system is, thus, open-ended-the endothelial cells of its finest branches having overlapping junctions that open passively on demand. There is, therefore, no need to postulate that cancer cells actively invade the surrounding tissues. In addition, the breast stroma contains endothelial cells in which the luminal side is not apposed to that of the same or another endothelial cell. These, like other endothelial cells, are attached to the connective tissue elements on one side only. It is suggested that they provide a series of potential spaces that can conduct fluid rapidly through the tissues, providing the epithelial cells with a copious supply of nutrients. This irrigation system is termed the lymphatic labyrinth, to distinguish it from the classical sinusoids and collecting vessels of the drainage system.

Stromal changes in early invasive breast carcinoma. An immunohistochemical, histoenzymological and ultrastructural study

The purpose of this work was to detect in periductal connective tissue of breast carcinoma in situ changes induced by intraductal tumor cells before any dehiscence in basement membrane. Histological, electron microscopic, immunohistochemical and histoenzymological methods were used in 3 carcinomas in situ, 4 microinvasive carcinomas and 13 control invasive carcinomas. We could demonstrate a high functional activity of fibroblasts with secretion of mucopolysaccharides and type III collagen around intraductal carcinomas. These changes occurred simultaneously to those of the basement membrane which was either thinning or thickening. Any dehiscence in basement membrane secondarily induced in this periductal stroma the usual changes seen in invasive stroma, peculiarly numerous vascular pedicles, myofibroblasts, elastic material. These periductal stromal changes are interpreted according to recent concepts about the possible influence of tumor cells upon their environment: stimulation of mitotic and metabolic activity of fibroblasts: stimulation of angiogenesis by means of an angiogenic factor.

Detection by in situ hybridization of messenger RNAs of collagen types I and IV in murine mammary cancer

Ten breast carcinomas developing in C3H/Bi female mice were studied by an in situ hybridization technique using cDNA probes encoding alpha-I chains of collagens of types I and IV. The results obtained are compared to histochemical data on antibodies to collagens of types I and IV and ultrastructural observations on these tumors. Immunohistochemistry has revealed the presence of type-IV collagen in basement membranes lining intraductal and well-differentiated cancer nests. Type-I collagen was detected in the stroma surrounding these cells. There was no cellular labelling when these antisera were used. In situ hybridization has shown that type-IV collagen mRNA is detected in non-invasive intraductal and well-differentiated tumor cells and in endothelial cells in the stroma. Good correlation between detection of type-IV collagen lining these cells and evidence of mRNA by in situ hybridization was thus observed. Invasive cancer cells did not express hybridization grains with the type-IV collagen probe. Type-I collagen mRNA was visualized in stromal cells, probably fibroblasts and myofibroblasts as shown by electron microscopy. The most active cells were localized close to non-invasive areas. Our data indicate persistent in-vivo biosynthesis of type-IV collagen by some cancer cells that produce their own limitative environment; they suggest that type-IV collagen is not produced by invasive tumor cells and that stromal cells lining the non-invasive regions have a peculiar behavior.

Electron microscopy of large cell undifferentiated and giant cell tumors

Electron microscopy is a valuable morphologic method for the diagnostic evaluation of undifferentiated tumors composed of polygonal or oval large cells and mononuclear or multinucleated giant cells. Although few ultrastructural details are pathognomonic, electron microscopic findings may add significantly to the formulation of the final diagnosis if used in the context of other pathomorphologic and clinical data. Contributions of electron microscopy to tumor diagnosis are summarized and illustrated with appropriate examples from personal experience in a routine university hospital laboratory.