The basement membrane in experimentally induced atypias and carcinoma of the uterine cervix in mice. An immunofluorescence study

Three-dimensional context regulation of metastasis

Tumor progression ensues within a three-dimensional microenvironment that consists of cellular and non-cellular components. The extracellular matrix (ECM) and hypoxia are two non-cellular components that potently influence metastasis. ECM remodeling and collagen cross-linking stiffen the tissue stroma to promote transformation, tumor growth, motility and invasion, enhance cancer cell survival, enable metastatic dissemination, and facilitate the establishment of tumor cells at distant sites. Matrix degradation can additionally promote malignant progression and metastasis. Tumor hypoxia is functionally linked to altered stromal-epithelial interactions. Hypoxia additionally induces the expression of pro-migratory, survival and invasion genes, and up-regulates expression of ECM components and modifying enzymes, to enhance tumor progression and metastasis. Synergistic interactions between matrix remodeling and tumor hypoxia influence common mechanisms that maximize tumor progression and cooperate to drive metastasis. Thus, clarifying the molecular pathways by which ECM remodeling and tumor hypoxia intersect to promote tumor progression should identify novel therapeutic targets.

Can cancer be reversed by engineering the tumor microenvironment?

To advance cancer research in a transformative way, we must redefine the problem. Although epithelial cancers, such as breast cancer, may be caused by random somatic gene mutations, the reality is that this is only one of many ways to induce tumor formation. Cancers also can be produced in experimental systems in vitro and in vivo, for example, by inducing sustained alterations of extracellular matrix (ECM) structure. Moreover, certain epithelial cancers can be induced to 'reboot' and regenerate normal tissue morphology when combined with embryonic mesenchyme or exogenous ECM scaffolds that are produced through epithelial-stromal interactions. At the same time, work in the field of Mechanical Biology has revealed that many cell behaviors critical for cancer formation (e.g., growth, differentiation, motility, apoptosis) can be controlled by physical interactions between cells and their ECM adhesions that alter the mechanical force balance in the ECM, cell and cytoskeleton. Epithelial tumor progression also can be induced in vitro by changing ECM mechanics or altering cytoskeletal tension generation through manipulation of the Rho GTPase signaling pathway. Mechanical interactions between capillary cells and ECM that are mediated by Rho signaling similarly mediate control of capillary cell growth and angiogenesis, which are equally critical for cancer progression and metastasis. These findings question basic assumptions in the cancer field, and raise the intriguing possibility that cancer may be a reversible disease that results from progressive deregulation of tissue architecture, which leads to physical changes in cells and altered mechanical signaling. This perspective raises the possibility of developing a tissue engineering approach to cancer therapy in which biologically inspired materials that mimic the embryonic microenvironment are used to induce cancers to revert into normal tissues.

Characterisation of the progression of azaserine-induced rat pancreatic adenocarcinoma by proliferative cell nuclear antigen, basement membrane laminin and trypsinogen immunohistochemistry

The progression of azaserine-induced rat pancreatic adenocarcinoma (AC) was characterised using quantitative and semiquantitative immunohistochemistry for proliferating cell nuclear antigen (PCNA), basement membrane laminin (BML) and trypsinogen (TG). Samples were taken 5-20 months after initiation. High PCNA-labelling indices (PCNA LIs) were measured 5 months after the induction of atypical acinar cell nodules (AACNs), which decreased later and stagnated until a further decline in the month 10 adenomas. Then a second premalignant proliferative wave was observed (month 13) within the adenoma stage. Later, in month 20 differentiated ACs PCNA LIs fell to the host tissue level but were found highest in the month 20 anaplastic ACs indicating a switch to malignant proliferation. Month 20 invasive ACs showed a number of separate proliferative foci. In early AACNs, BML decreased and remained low till the local maximum in the month 13 adenoma. Invasive ACs did not express BML. Month 5 AACN and differentiated AC were TG deficient but anaplastic AC regained its TG expression. However invasive AC was again TG negative. These results are discussed in combination with our previous data on progressional changes of autophagic capacity and microvessel densities.

Cancer as a disease of epithelial-mesenchymal interactions and extracellular matrix regulation

Carcinogenesis - the process of cancer formation - is commonly discussed in terms of genetic alterations that lead to deregulation of cell growth. Recently, there has been a resurgence of interest in epigenetic factors and, in particular, the role of the stromal microenvironment and angiogenesis in tumor formation. In this article, cancer is presented as a disease of the developmental processes that govern how cells organize into tissues and tissues into organs. This histogenetic perspective raises the possibility that epithelial-mesenchymal interactions and the extracellular matrix (basement membrane) that is deposited through these interactions may actively contribute to the carcinogenic process. Experimental work is reviewed that confirms that extracellular matrix plays a key role in normal histodifferentiation during both epitheliogenesis and angiogenesis, and that epigenetic deregulation of cell-matrix interactions may actively promote tumor initiation and progression. The contributions of integrins, cytoskeleton, tensegrity and local variations in extracellular matrix mechanics to these processes are discussed, as are the implications of this work for future studies on cancer formation.

Loss of basement membrane deposits and development of invasive potential by virally-transformed rat mammary cells are independent of collagenase production

The myoepithelial-type cell line, Rama 712, derived from a normal rat mammary gland, deposits an extracellular matrix containing type-IV collagen and other basement membrane proteins round its cellular periphery. After transformation with a temperature-sensitive mutant of Rous sarcoma virus (tsRSV) the cells fail to deposit an extracellular matrix at the permissive temperature (35 degrees C), but retain the capacity to do so at the non-permissive temperature (41 degrees C). The synthesis of type-IV collagen is not affected by the temperature shift. Rama 712 cells fail to form tumours in syngeneic rats. However, Rama 712-tsRSV cells form tumours that are locally invasive but fail to metastasize. In histological sections, the tumour cells stain with an antibody to type-IV collagen, but do not deposit any extracellular type-IV collagen. Cells isolated from the tumours (Rama 712T) remain temperature-sensitive for the extracellular deposition of type-IV collagen when grown in vitro. Rama 712, Rama 712-tsRSV and Rama 712T fail to produce any detectable type-I or type-IV collagenase at either 35 degrees C or 41 degrees C. These results show that in this system extracellular deposits of basement membrane proteins are lost from invasive tumours produced by myoepithelial-type cells by mechanisms other than those due to the production of collagenolytic enzymes.

The basal lamina in basal cell carcinoma, Bowen's disease, squamous cell carcinoma and keratoacanthoma: an immunoperoxidase study using an antibody to type IV collagen

The basal lamina in a variety of skin tumours was assessed with an antibody to type IV collagen and the peroxidase-antiperoxidase (PAP) technique. The antibody was raised in rabbits against type IV collagen isolated from human placental tissue. The basal lamina in Bowen's disease was essentially intact while squamous cell and basal cell carcinomas showed focal loss in areas of tumour cell invasion. However, both tumours showed preservation of basal lamina around the majority of projections and nests of tumour within the dermis. Many keratoacanthomas showed extensive loss of the basal lamina. This loss appears associated with advanced keratinization at the base of the lesion and may represent an involutional change possibly secondary to inflammation. It is concluded that epidermal tumour cells following local invasion may cease migration and produce a distinct continuous basal lamina similar to that of the normal dermo-epidermal junction. Loss of basal lamina appears restricted to foci of ongoing tumour invasion.

The basement membrane in the carcinoma in situ of the cervix: a morphological study

A morphological study of the basement membrane in the carcinoma in situ of the cervix has been carried out. Undifferentiated carcinoma in situ that arises usually from the squamocolumnar junction and which extends into the endocervical canal, always shows a continuous and clearly delineated basement membrane, which runs parallel to the basal layer. It has a homogeneous appearance. The hemidesmosomes attached to the lamina propria are quite normal and there are no slender protrusions from basal cells into the lamina propria. Differentiated carcinoma in situ, that originates in the squamous epithelium of the portio, may extend either in the direction of vagina, or towards the endocervical canal. It is always underlined by a basement membrane loosely constituted of irregular of fragmented reticular fibers; it frequently looses its homogeneous appearance and may be dehiscent or duplicated. Basal cells send down small pseudopods or threadlike extensions into the lamina propria. The authors suggest that in the management of carcinoma in situ of the cervix, one should take into consideration the direction of spread and the stroma-invasion potential of the carcinoma. These histologic patterns carry with them a very important morphologic implication, namely 'cells differentiation' of the carcinoma.

Role of basal lamina in neoplastic disorganization of tissue architecture

We have studied a transplantable carcinoma of the rat pancreas [Reddy, J. K. & Rao, M. S. (1977( Science 198, 78-80] that is composed of cytologically differentiated acinar cells that have lost their epithelial orientation and do not form acini. Light microscopy shows, however, consistent palisading, reorientation, and polarization of these cells in areas of contact with the vasculature. Electron microscopy reveals a normal basal lamina (BL) along the basal portions of repolarized tumor cells that is physically separate from the endothelial BL. We used indirect immunofluorescence to examine the distribution of BL constituents, laminin (Lm) and type IV collagen (type IV), within the different microenvironments of this tumor. In normal pancreas, Lm and type IV are distributed linearly, outlining acini and blood vessels. In the tumor parenchyma, type IV is not detected, whereas Lm appears in a punctate distribution outlining cells. Reorientation of tumor cells is observed only along linearly deposited Lm and type IV bordering vessels. These data indicate that this nonmetastatic tumor has lost the ability to produce or maintain a complete BL within its disorganized parenchyma, while its cells retain the capacity to produce and reorganize along liner BL when in contact with vascular adventitia. We suggest that failure to maintain a complete BL may be involved in the neoplastic disorganization of normal tissue architecture as well as in the breakdown of boundaries during the development of invasive carcinomata.