Suppression of ICE and Apoptosis in Mammary Epithelial Cells by Extracellular Matrix Nancy Boudreau,* Carolyn J. Sympson, Zena Werb, Mina J. Bissell N. Boudreau and M. J. Bissell Life Sciences Division, Lawrence Berkeley Laboratory 1 Cyclotron Road, Building 83, Berkeley, CA 94720, USA. C. J. Sympson Life Sciences Division, Lawrence Berkeley Laboratory 1 Cyclotron Road, Building 83, Berkeley, CA 94720, USA Laboratory of Radiobiology and Environmental Health University of California, San Francisco, CA 94143, USA. Z. Werb Laboratory of Radiobiology and Environmental Health University of California, San Francisco, CA 94143, USA. *To whom correspondence should be addressed. LBNL/DOE funding & contract number: DE-AC02-05CH11231 DISCLAIMER This document was prepared as an account of work sponsored by the United States Government. While this document is believed to contain correct information, neither the United States Government nor any agency thereof, nor The Regents of the University of California, nor any of their employees, makes any warranty, express or implied, or assumes any legal responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by its trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or The Regents of the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof or The Regents of the University of California.

Suppression of ICE and Apoptosis in Mammary Epithelial Cells by Extracellular Matrix

Three-dimensional tissue culture models in cancer biology.

Ras signalling and apoptosis.

Apoptosis following loss of cell anchorage is of relevance for development, tissue homeostasis and disease. In the following the role of cell-matrix anchorage as well as cell-cell anchorage for cell survival and apoptosis is reviewed and the complex molecular mechanisms inducing and perpetuating detachment-induced apoptosis will be discussed with special emphasis on the role of caspases, p53, bcl-2 family members and the Fas signaling pathway.

Molecular mechanisms of “detachment-induced apoptosis—Anoikis”

This article reviews actual advances in the development and application of three-dimensional (3-D) cell culture systems. Recent therapeutically oriented studies include characterization of multicellular-mediated drug resistance, novel ways of quantifying hypoxia, and new approaches to more efficient immunotherapy. Recent progress toward understanding the development of necrosis in tumor spheroids has been made using novel spheroid models. 3-D cultures have been used for studies on molecular mechanisms involved in invasion and metastasis, with a major focus on the role of E-cadherin. Similarly, tumor angiogenesis and the significance of vascular endothelial growth factor have been investigated in a variety of 3-D culture systems. There are many ongoing developments in tissue modeling or remodeling that promise significant progress toward the development of bioartificial liver support and artificial blood. Perhaps one of the most interesting areas of basic research with 3-D cultures is the characterization of embryoid bodies obtained from stable embryonic stem cells. These models have greatly increased the understanding of embryonic development, in particular through the notable exceptional advances in cardiogenesis.

Three-dimensional cell cultures: from molecular mechanisms to clinical applications.

Deregulation of molecular pathways controlling cell survival and death, including programmed cell death, are thought to be important factors in tumor formation, disease progression, and response to therapy. Studies devoted to analyzing the role of programmed cell death in cancer have been carried out primarily using conventional monolayer cell culture systems. However the majority of cancers grow as three-dimensional solid tumors. Because gene expression, and possibly function, can be significantly altered under such conditions, we decided to analyze the control and characteristics of cell death using a compatible three-dimensional tissue culture system (multicellular spheroids) and compare the results obtained to those using two-dimensional monolayer cell culture. To do so we selected for study an immortalized, but nontumorigenic line of rat intestinal epithelial cells, called IEC-18, and several tumorigenic variants of IEC-18 obtained by transfection with a mutant (activated) c-H-ras oncogene. The rationale for choosing these cell lines was based in part on the fact that intestinal epithelial cells grow in vivo in a monolayer-like manner and form solid tumors only after sustaining certain genetic mutations, including those involving the ras gene family. We found that the IEC-18 cells, which grow readily and survive in monolayer cell culture, undergo massive cell death within 48-72 h when cultured as multicellular spheroids on a nonadhesive surface. This process was accompanied by a number of features associated with programmed cell death including chromatin condensation (Hoechst 33258 staining) apoptotic morphology, DNA degradation, and a virtual complete loss of colony forming (clonogenic) ability in the absence of apparent membrane damage as well as accumulation of lipid containing vacuoles in the cytoplasm. Moreover, enforced over-expression of a transfected bcl-2 gene could prevent this cell death process from taking place. In marked contrast, three different stably transfected ras clones of IEC-18 survived when grown as multicellular spheroids. In addition, an IEC cell line (called clone 25) carrying its mutant transfected ras under a glucocorticoid inducible promoter survived in three-dimensional culture only when the cells were exposed to dexamethasone. If exposure to dexamethasone was delayed for as long as 48 h the cells nevertheless survived, whereas the cells became irreversibly committed to programmed cell death (PCD) if exposed to dexamethasone after 72 h. These results suggest that intestinal epithelial cells may be programmed to activate a PCD pathway upon detachment from a physiologic two-dimensional monolayer configuration, and that this process of adhesion regulated programmed cell death (ARPCD) can be substantially suppressed by expression of a mutant ras oncogene.(ABSTRACT TRUNCATED AT 400 WORDS)

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Massive programmed cell death in intestinal epithelial cells induced by three-dimensional growth conditions: suppression by mutant c-H-ras oncogene expression.

Shao-nan Huang

Papers

Massive programmed cell death in intestinal epithelial cells induced by three-dimensional growth conditions: suppression by mutant c-H-ras oncogene expression.