Invasion and metastases of cancer cells and the development of resistance to anticancer therapies are the main causes of morbidity and mortality from cancer. For more than two decades, these two important but not clearly related aspects in the biology of cancer have been extensively studied. Specifically, P-glycoprotein and CD44 have been characterized and are known to be determinants of multidrug resistance (MDR) and metastases. Despite this body of knowledge, few reports have linked the two phenotypes and only recently have there been reasons to suspect a direct connection. In this report, we show that a novel physical and genetic interaction between CD44s and P-glycoprotein is in part responsible for the correlation between MDR and invasive potential in cancer cells. P-glycoprotein-specific substrates that interfere with its function reduced in vitro invasion, migration, and the physical colocalization of CD44s and P-glycoprotein. CD44 expression in sensitive cells promoted the expression of P-glycoprotein and the MDR phenotype. RNA interference of MDR1 inhibited the rate of cell migration. These data indicate that there is a close interaction between CD44 and P-glycoprotein that results in the concurrent expression and modulation of two malignant phenotypes, invasion and MDR.

Implantation of demineralized diaphyseal bone matrix in subcutaneous sites induces a sequence of events resulting in the local differentiation of endochondral bone. Demineralized bovine bone matrix was dissociatively extracted in 4.0 M guanidine hydrochloride and the bone-inductive proteins were purified >12,000-fold. The purification steps include affinity chromatography on heparin-Sepharose, hydroxyapatite chromatography, gel filtration, and C18 reversephase HPLC. Since the purified protein in conjunction with insoluble collagenous bone matrix induced new bone differentiation in vivo we have designated this component osteogenin. The osteogenic potential is specific for osteogenin and is not exhibited by previously isolated growth factors.The remarkable potential for regeneration and repair in bone has been known from the days of Hippocrates in ancient Greece. It has been suspected that in bone there may be a substance, osteogenin, that might initiate bone growth (1). Implantation of demineralized diaphyseal bone matrix in intramuscular and subcutaneous sites results in local bone differentiation (2,3), and it is possible osteogenins are present in the matrix. The sequential developmental cascade in response to the implantation of matrix consists of the following major phases: chemotaxis and attachment of mesenchymal stem cells to the matrix, proliferation of progenitor cells, and differentiation of cartilage, bone, and hematopoietic marrow (3)(4)(5). Progress in the isolation of osteogenins has been slow due to the fact that bone matrix is in the solid state. We have shown that the endochondral bone-differentiation activity of bone matrix could be dissociatively extracted and reconstituted with inactive residual collagenous matrix to restore full bone-induction activity (6). This advance provided a method for assaying soluble components for their ability to induce endochondral bone differentiation in vivo and permitted their further purification. The putative differentiation factors have a molecular mass of <50 kDa (6), appear to be homologous in several species of mammals (7), stimulate fibroblast proliferation (8), and transform mesenchymal cells derived from muscle into chondrocytes in vitro (9). Aggregates of the bone morphogenetic protein and other proteins from bovine demineralized matrix induce formation of new bone (10). The osteoinductive potential of demineralized bone matrix was inhibited by pretreatment with heparinized plasma (11) and heparin (12), possibly by binding to the active sites in the matrix. In view of this we have explored the utility of heparin affinity columns to purify bone-inductive protein. We report here the isolation of bone-inductive protein, osteogenin from bovine demineralized bone matrix, using heparin affinity chromatography and reverse-phase HPLC. MATERIALS AND METHODSDissociative Extraction and Ethanol Precipitation. Dehydrated diaphyseal bovine bone matrix powder (particle size, 74-420 Am) was demineralized. Two hundred grams of acid-demineralized bovine bone mat...

Reconstituted Living Skin Equivalent (LSE) is made up of a dermal equivalent (DE) on which keratinocytes are plated where they give rise to a multilayered differentiated epidermis. The dermal equivalent develops through interactions between fibroblasts and collagen fibrils that begin to form after the cell-matrix precursor is cast. The gel that forms as a result of collagen polymerization and fluid trapping is contracted uniformly in all dimensions. By securing it at ends and edges in the mold in which it is cast, the final dimensions, strength and morphology of the forming tissue are altered. The same phenomena are seen in casting tubular tissues for the fabrication of small caliber blood vessel equivalents. The cells of the dermal equivalent are biosynthetically active and enrich the matrix to different degrees with secretory products, depending on how the cells are stimulated and on the presence or absence of an epidermis. Collagen biosynthesis by dermal cells in the DE is sensitive to growth factors, ascorbate concentrations and amino acid pools. Both ascorbate and TGF beta 1 increase total collagen biosynthesis at least two-fold by one week after tissue formation. With TGF beta 1 present, the capacity of cells in the DE to synthesize collagen increases with time, over a two-week period. If ascorbate (200 micrograms/ml) is added just after the tissue is cast and daily thereafter, contraction lattice is blocked, and collagen biosynthesis is enhanced relative to contracted controls that had received 200 micrograms/ml ascorbate once. The increase was nearly an order of magnitude over that of controls and was coordinate with a comparable increase in hyaluronate and sulfated glycosaminoglycan (GAG) production as shown by TCA-precipitable glucosamine in the intercellular matrix of the DE. Both the LSE and the Living Dermal Equivalent (LDE) exhibit complex responses to UV radiation and to various chemicals that are greatly different from responses given by monolayered cells.(ABSTRACT TRUNCATED AT 250 WORDS)

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Chronic inflammation is implicated in the pathophysiology of ovarian cancer. Tumor necrosis factor-A (TNF-A), a major inflammatory cytokine, is abundant in the ovarian cancer microenvironment. TNF-A modulates the expression of CD44 in normal T lymphocytes and CD44 is implicated in ovarian carcinogenesis and metastases. However, little is known about the role of TNF-A in CD44 expression of cancer cells. Recent clinical work using TNF-A inhibitors for the treatment of ovarian cancer makes the study of TNF-A interactions with CD44 crucial to determining treatment a success or a failure. We studied the effect of TNF-A on ovarian cancer cells viability, CD44 expression, and in vitro migration/invasion. Our results revealed that TNF-A differentially modulates the expression of CD44 in TNF-A-resistant ovarian cancer cells, affecting their in vitro migration, invasion, and binding to hyaluronic acid. TNF-A up-regulation of CD44 expression was dependent on the activation of c-Jun NH 2 -terminal kinase (JNK) and this activation was accompanied by an increase in their invasive phenotype. On the contrary, if TNF-A failed to induce JNK phosphorylation, the end result was down-regulation of both CD44 expression and the invasive phenotype. These results were confirmed by the use of JNK inhibitors and a TNF receptor competitive inhibitor.

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The cellular and molecular basis of bone development and its regulation by differentiation and growth factors is an exciting area of current research. This article briefly reviews the historical progress in the isolation of osteogenin, a novel bone differentiation factor, and its modulation by well known growth factors. Endochondral bone development is a multistep sequential cascade and the process must be operationally dissected. It has been accomplished with the demineralized bone matrix-induced bone formation model. The reproducible development of cartilage and bone in an extraskeletal site permits the study of the initiation of the first cycle of endochondral bone formation and mineralization. Recent progress in the isolation of osteogenin, a specific bone differentiation factor, by heparin affinity chromatography permits the further investigation of the commitment and clonal expansion of the putative osteoprogenitor stem cells. Once initiated, bone formation is promoted by growth factors such as platelet derived growth factor, fibroblast growth factor, insulin like growth factor, transforming growth factor beta and a plethora of non specific cytokines. Finally bone development is further modulated by systemic hormones and nutrition and a host of physical signals including electrical, gravitational and mechanical forces.

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