Human adenocarcinoma (AC) is the most frequently diagnosed human lung cancer, and its absolute incidence is increasing dramatically. Compared to human lung AC, the A/J mouse-urethane model exhibits similar histological appearance and molecular changes. We examined the gene expression profiles of human and murine lung tissues (normal or AC) and compared the two species' datasets after aligning approximately 7500 orthologous genes. A list of 409 gene classifiers (P value <0.0001), common to both species (joint classifiers), showed significant, positive correlation in expression levels between the two species. A number of previously reported expression changes were recapitulated in both species, such as changes in glycolytic enzymes and cell-cycle proteins. Unexpectedly, joint classifiers in angiogenesis were uniformly down-regulated in tumor tissues. The eicosanoid pathway enzymes prostacyclin synthase (PGIS) and inducible prostaglandin E(2) synthase (PGES) were joint classifiers that showed opposite effects in lung AC (PGIS down-regulated; PGES up-regulated). Finally, tissue microarrays identified the same protein expression pattern for PGIS and PGES in 108 different non-small cell lung cancer biopsies, and the detection of PGIS had statistically significant prognostic value in patient survival. Thus, the A/J mouse-urethane model reflects significant molecular details of human lung AC, and comparison of changes in orthologous gene expression may provide novel insights into lung carcinogenesis.

The cell surface heparan sulfate proteoglycan syndecan-1 is induced in stromal fibroblasts of breast carcinomas and participates in a reciprocal feedback loop, which stimulates carcinoma cell growth in vitro and in vivo. To define the molecular mechanism of carcinoma growth stimulation, a three-dimensional coculture model was developed that combines T47D breast carcinoma cells with immortalized human mammary fibroblasts in collagen gels. By silencing endogenous syndecan-1 induction with short interfering RNA and expressing mutant murine syndecan-1 constructs, it was determined that carcinoma cell mitogenesis required proteolytic shedding of syndecan-1 from the fibroblast surface. The paracrine growth signal was mediated by the syndecan-1 heparan sulfate chains rather than the ectodomain of the core protein and required fibroblast growth factor 2 and stroma-derived factor 1. This paracrine pathway may provide an opportunity for the therapeutic disruption of stromaepithelial signaling.The mammary epithelium and stromal elements co-evolve during cancer development. As the carcinoma progresses, stromal fibroblasts are recruited, and their phenotype is altered through the action of growth factors and cytokines. The resulting tumor-associated stroma is recognized by pathologists as desmoplasia and forms a permissive and supportive environment for tumor growth (1). Compared with normal stromal fibroblasts, breast carcinoma-associated fibroblasts display distinct gene expression and phenotypic changes (2-4). In turn, carcinoma-associated fibroblasts modify the growth, differentiation, and invasive behavior of carcinoma cells (5, 6). Breast stromal fibroblasts can modulate carcinoma cell proliferation both in vitro and in vivo (7,8). The emerging picture implicates soluble paracrine growth factors and extracellular matrix components in stroma-to-carcinoma cell signaling, but our understanding of these reciprocal pathways is presently incomplete.We and others have recently observed a dramatic overexpression of the cell surface heparan sulfate proteoglycan (HSPG) 2 syndecan-1 (Sdc1) in stromal fibroblasts of invasive breast carcinomas (9, 10). Sdc1 consists of an extracellular domain carrying heparan sulfate glycosaminoglycan (HSGAG) and chondroitin sulfate glycosaminoglycan (CSGAG), a transmembrane domain and a cytoplasmic domain. The biological functions of Sdc1 are not fully understood, but co-receptor roles in signaling of HSGAG-dependent growth factors and in cell adhesion events are well documented. Most of these activities are mediated through the HSGAG chains, but core protein-specific functions have also been described (11,12). The Sdc1 ectodomain can be shed from the cell surface by proteolytic cleavage at a juxtamembrane site (13). The shed Sdc1 ectodomain retains its biologically active heparan sulfate chains and has been found to promote growth of myeloma tumors in vivo (14).Syndecan-1 is normally expressed in many types of epithelia and plasma cells. Mesenchymal Sdc1 expression has been observed during the de...

Activating mutations in ras genes are frequently associated with non-small cell lung cancer cells (NSCLC) and contribute to transformed growth in these cells. Expression of oncogenic forms of Ras in these cells is associated with increased expression and activity of cytosolic phospholipase A 2 (cPLA 2 ) and cyclooxygenase-2 (COX-2), leading to constitutively elevated levels of prostaglandin production. Expression of oncogenic Ras is sufficient to induce these enzymes in normal lung epithelial cells. We have previously reported that the JNK and ERK pathways are necessary for induction of cPLA 2 and have defined a minimal region of the cPLA 2 promoter from ؊58 to ؊12 that is required for Ha-Ras-mediated induction. To further characterize the cis-regulatory elements within this region involved in this response, site-directed mutagenesis was used to make mutations at various sites. Three cis-regulatory elements were identified: regions ؊21/؊18, ؊37/؊30, and ؊55/؊53. Mutations in any of these elements decreased basal and Ha-Ras-induced cPLA 2 promoter activity in both normal lung epithelial cells, as well as steady state promoter activity in A549 cells, with a mutation in element ؊21/؊18 completely eliminating all promoter activity. Overexpression studies and gel shift assays indicated that Sp1 may serve as a transcription factor functionally regulating promoter activity by directly interacting with two of the cis-regulatory elements, ؊21/؊18 and ؊37/؊30. Expression of Ha-Ras led to induction of c-Jun protein, which showed functional cooperation with Sp1 in driving promoter activity. Additional unidentified transcription factors bound to the regions from ؊55/؊53 and ؊37/؊34.

Mounting evidence implicates stromal fibroblasts in breast carcinoma progression. We have recently shown in threedimensional coculture experiments that human mammary fibroblasts stimulate the proliferation of T47D breast carcinoma cells and that this activity requires the shedding of the heparan sulfate proteoglycan syndecan-1 (Sdc1) from the fibroblast surface. The goal of this project was to determine the mechanism of Sdc1 ectodomain shedding. The broad spectrum matrix metalloproteinase (MMP) inhibitor GM6001 specifically blocked Sdc1-mediated carcinoma cell growth stimulation, pointing toward MMPs as critical enzymes involved in Sdc1 shedding. MMP-2 and membrane type 1 MMP (MT1-MMP) were the predominant MMPs expressed by the mammary fibroblasts. Fibroblast-dependent carcinoma cell growth stimulation in three-dimensional coculture was abolished by MT1-MMP expression silencing with small interfering RNA and restored either by adding recombinant MT1-MMP catalytic domain or by expressing a secreted form of Sdc1 in the fibroblasts. These findings are consistent with a model where fibroblast-derived MT1-MMP cleaves Sdc1 at the fibroblast surface, leading to paracrine growth stimulation of carcinoma cells by Sdc1 ectodomain. The relevance of MT1-MMP in paracrine interactions was further supported by coculture experiments with T47D cells and primary fibroblasts isolated from human breast carcinomas or matched normal breast tissue. Carcinoma-associated fibroblasts stimulated T47D cell proliferation significantly more than normal fibroblasts in three-dimensional coculture. Function-blocking anti-MT1-MMP antibody significantly inhibited the T47D cell growth stimulation in coculture with primary fibroblasts. In summary, these results ascribe a novel role to fibroblastderived MT1-MMP in stromal-epithelial signaling in breast carcinomas. [Cancer Res 2008;68(22):9558-65]

SUMMARYStudies in both humans and rodents have found that insulin + cells appear within or near ducts of the adult pancreas, particularly following damage or disease, suggesting that these insulin + cells arise de novo from ductal epithelium. We have found that insulin + cells are continuous with duct cells in the epithelium that makes up the hyperplastic ducts of both chronic pancreatitis and pancreatic cancer in humans. Therefore, we tested the hypothesis that both hyperplastic ductal cells and their associated insulin + cells arise from the same cell of origin. Using a mouse model that develops insulin + cell-containing hyperplastic ducts in response to the growth factor TGF, we performed genetic lineage tracing experiments to determine which cells gave rise to both hyperplastic ductal cells and duct-associated insulin + cells. We found that hyperplastic ductal cells arose largely from acinar cells that changed their cell fate, or transdifferentiated, into ductal cells. However, insulin + cells adjacent to acinar-derived ductal cells arose from pre-existing insulin + cells, suggesting that islet endocrine cells can intercalate into hyperplastic ducts as they develop. We conclude that apparent pancreatic plasticity can result both from the ability of acinar cells to change fate and of endocrine cells to reorganize in association with duct structures.