Adhesive defect in extracellular matrix tenascin-X-null fibroblasts: a possible mechanism of tumor invasion

Tenascin-X in amniotic fluid and reproductive tissues of pregnancies complicated by infection and preterm prelabor rupture of membranes†

Preterm prelabor rupture of membranes (PPROM), which can precede or follow intra-amniotic infection/inflammation (IAI), is a poorly understood pregnancy complication. Tenascin-X (TNX) is a connective tissue extracellular matrix protein that regulates fibrillogenesis of collagens I, III, and V. Our goal was to investigate the presence and level of soluble TNX (sTNX) in amniotic fluid (AF) and TNX expression in reproductive tissues of pregnancies complicated by PPROM and IAI. We prospectively recruited 334 women pregnant with singletons who had a clinically indicated amniocentesis for genetic karyotyping, lung maturity testing, or rule-out IAI in the presence or absence of PPROM. We quantified TNX expression in fetal membranes, myometrium, cervix, and placenta using immunological methods and qRT-PCR. In pregnancies with normal outcomes, AF sTNX levels were GA-regulated with lower levels toward term. IAI significantly upregulated AF sTNX levels independent of membrane status. AF sTNX levels inversely correlated with fetal membranes tenascin XB (TNXB) mRNA level, which was significantly downregulated by IAI. Western blotting identified characteristic ∼75 and ∼140 kDa sTNX forms in both AF and fetal membranes. Fetal membranes, placenta, and cervix constitutively express TNX with the highest abundance in the amnion. Amnion TNX richness is significantly lost in the setting of IAI. Our results suggest that fetal membranes may be a source of AF sTNX whereby protein and mRNA expression seem to be significantly impacted by inflammation independent of fetal membrane status. A more thorough understanding of TNX changes may be valuable for understanding spontaneous PPROM and to potentially develop therapeutic targets.

Loss of Tenascin-X expression during tumor progression: A new pan-cancer marker

Cancer is a systemic disease involving multiple components produced from both tumor cells themselves and surrounding stromal cells. The pro- or anti-tumoral role of the stroma is still under debate. Indeed, it has long been considered the main physical barrier to the diffusion of chemotherapy by its dense and fibrous nature and its poor vascularization. However, in murine models, the depletion of fibroblasts, the main ExtraCellular Matrix (ECM)-producing cells, led to more aggressive tumors even though they were more susceptible to anti-angiogenic and immuno-modulators. Tenascin-C (TNC) is a multifunctional matricellular glycoprotein (i.e. an ECM protein also able to induce signaling pathway) and is considered as a marker of tumor expansion and metastasis. However, the status of other tenascin (TN) family members and particularly Tenascin-X (TNX) has been far less studied during this pathological process and is still controversial. Herein, through (1) in silico analyses of the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases and (2) immunohistochemistry staining of Tissue MicroArrays (TMA), we performed a large and extensive study of TNX expression at both mRNA and protein levels (1) in the 6 cancers with the highest incidence and mortality in the world (i.e. lung, breast, colorectal, prostate, stomach and liver) and (2) in the cancers for which sparse data regarding TNX expression already exist in the literature. We thus demonstrated that, in most cancers, TNX expression is significantly downregulated during cancer progression and we also highlighted, when data were available, that high TNXB mRNA expression in cancer is correlated with a good survival prognosis.

Secretome Identifies Tenascin-X as a Potent Marker of Ovarian Cancer

CA-125 has been a valuable marker for the follow-up of ovarian cancer patients but it is not sensitive enough to be used as diagnostic marker. We had already used secretomic methods to identify proteins differentially secreted by serous ovarian cancer cells compared to healthy ovarian cells. Here, we evaluated the secretion of these proteins by ovarian cancer cells during the follow-up of one patient. Proteins that correlated with CA-125 levels were screened using serum samples from ovarian cancer patients as well as benign and healthy controls. Tenascin-X secretion was shown to correlate with CA-125 value in the initial case study. The immunohistochemical detection of increased amount of tenascin-X in ovarian cancer tissues compared to healthy tissues confirms the potent interest in tenascin-X as marker. We then quantified the tenascin-X level in serum of patients and identified tenascin-X as potent marker for ovarian cancer, showing that secretomic analysis is suitable for the identification of protein biomarkers when combined with protein immunoassay. Using this method, we determined tenascin-X as a new potent marker for serous ovarian cancer.

Rat mammary extracellular matrix composition and response to ibuprofen treatment during postpartum involution by differential GeLC-MS/MS analysis

Breast cancer patients diagnosed within five years following pregnancy have increased metastasis and decreased survival. A hallmark of postpartum biology that may contribute to this poor prognosis is mammary gland involution, involving massive epithelial cell death and dramatic stromal remodeling. Previous studies show pro-tumorigenic properties of extracellular matrix (ECM) isolated from rodent mammary glands undergoing postpartum involution. More recent work demonstrates systemic ibuprofen treatment during involution decreases its tumor-promotional nature. Utilizing a proteomics approach, we identified relative differences in the composition of mammary ECM isolated from nulliparous rats and those undergoing postpartum involution, with and without ibuprofen treatment. GeLC-MS/MS experiments resulted in 20327 peptide identifications that mapped to 884 proteins with a <0.02% false discovery rate. Label-free quantification yielded several ECM differences between nulliparous and involuting glands related to collagen-fiber organization, cell motility and attachment, and cytokine regulation. Increases in known pro-tumorigenic ECM proteins osteopontin, tenascin-C, and laminin-α1 and pro-inflammatory proteins STAT3 and CD68 further identify candidate mediators of breast cancer progression specific to the involution window. With postpartum ibuprofen treatment, decreases in tenascin-C and three laminin chains were revealed. Our data suggest novel ECM mediators of breast cancer progression and demonstrate a protective influence of ibuprofen on mammary ECM composition.

The regulation of tenascin expression by tissue microenvironments

Tenascins are a family of four extracellular matrix proteins: tenascin-C, X, R and W. The four members of the family have strikingly diverse patterns of expression during development and in the adult organism indicating independent mechanisms of regulation. In this review we illustrate that there are two types of tenascins, those that are significantly regulated by the tissue microenvironment (tenascin-C and tenascin-W), and those that have stabile, restricted expression patterns (tenascin-R and tenascin-X). We summarize what is known about the regulation of tenascin expression by transforming growth factor betas, fibroblast growth factors, platelet derived growth factors, as well as pro- and anti-inflammatory cytokines or hormones that either induce or inhibit expression of tenascins.

Xq25 and Xq26 identify the common minimal deletion region in malignant gastroenteropancreatic endocrine carcinomas

Loss of heterozygosity (LOH) for markers on X chromosome are associated with malignancy in endocrine tumors of the stomach and pancreas. The aim of this work is to investigate low-grade, well-differentiated endocrine carcinomas (WDEC) vs high-grade, poorly differentiated endocrine carcinomas (PDEC) of the gastroenteropancreatic (GEP) tract for common deletion regions on X chromosome. We performed a comparative allelotyping analysis with 24 highly polymorphic markers for the X chromosome in 12 WDECs and 5 PDECs. Overall, the LOH frequency in all informative loci investigated was 59% in primary and 61% in metastasis, with a significantly higher rate in PDECs than in WDECs (p<0.015 for primary and p<0.00005 for metastasis). In both WDECs and PDECs, the small Xq25 region as defined by DXS8059, DXS8098, and DXS8009 markers showed higher LOH rate as compared to the rest of the chromosome markers (p<0.04). In addition, LOH was very frequently elevated also in DXS294 and in DXS102 loci mapping the chromosomal region Xq26. In no instances differences were found between primary tumors and metastases. Methylation analysis revealed that Xq25 loss preferentially occurred on the inactive X chromosome, a feature in agreement with findings from other human cancers suggesting escape of tumor suppressor genes to X chromosome inactivation at this region. Overall, our data indicate that the two chromosomal regions, Xq25 and Xq26, may participate to the malignant progression of GEP endocrine carcinomas.

Transplantation of reconstructed human skin on nude mice: a model system to study expression of human tenascin-X and elastic fiber components

Tenascin-X is a large extracellular matrix protein that is widely expressed in connective tissues during development and in the adult. Genetically determined deficiency of tenascin-X causes the connective tissue disease Ehlers-Danlos syndrome. These patients show reduced collagen density and fragmentation of elastic fibers in their skin. In vitro studies on the role of tenascin-X in elastic fiber biology are hampered because monolayers of fibroblasts do not deposit tenascin-X and elastic fibers into the extracellular matrix. Here, we applied an organotypic culture model of fibroblasts and keratinocytes to address this issue. We investigated the deposition of tenascin-X and elastin into skin-equivalent in vitro and also in vivo after transplantation onto immunodeficient mice. Whereas tenascin-C and fibrillin-1 were readily expressed in the skin-equivalents before transplantation, tenascin-X and elastin were not present. Three weeks post-grafting, a network of elastin was observed that coincided with the appearance of tenascin-X. At the ultrastructural level, microfibrils were observed, some of which were associated with elastin. Transplanted skin-equivalents containing tenascin-X-deficient fibroblasts showed deposition of immunoreactive elastin in similar quantities and distribution as those containing control fibroblasts. This suggests that tenascin-X is important for the stability and maintenance of established elastin fibers, rather than for the initial phase of elastogenesis. Thus, the transplantation of reconstructed skin on nude mice allows the study of tenascin-X and elastin expression and could be used as a model system to study the potential role of tenascin-X in matrix assembly and stability.

Deficiency of tenascin-X causes a decrease in the level of expression of type VI collagen

Tenascin-X (TNX) is an extracellular matrix glycoprotein. We previously demonstrated that TNX-null fibroblasts exhibit decreased cell-matrix and cell-cell adhesion. In this study, we used a differential display technique to determine the genes involved in this process. Differential display analysis of wild-type and TNX-null fibroblasts revealed that mRNA expression level of type VI collagen alpha3 is predominantly decreased in TNX-null fibroblasts. Expression levels of mRNAs of other subunits of type VI collagen, alpha2 and alpha3 chains, were also remarkably decreased in TNX-null fibroblasts. The protein level of alpha3 chain of type VI collagen was also reduced in TNX-null fibroblasts. However, the organization of type VI collagen in the extracellular matrix of TNX-null fibroblasts was similar to that of wild-type fibroblasts. Transient expression of TNX in Balb3T3 cells caused an increase in the level of mRNA of type VI collagen compared with that in vector control and increased the promoter activity of type VI collagen alpha1 subunit gene. In addition, the expression levels of type I collagen and other collagen fibril-associated molecules such as type XII and type XIV collagens, decorin, lumican and fibromodulin in wild-type and TNX-null fibroblasts were compared. It was found that the mRNA expression levels of type I collagen and collagen fibril-associated molecules other than decorin were decreased and that the expression level of decorin was increased in TNX-null fibroblasts. The results suggest the possibility that TNX mediates not only cell-cell and cell-matrix interactions but also fibrillogenesis via collagen fibril-associated molecules.

Incipient Alzheimer's disease: microarray correlation analyses reveal major transcriptional and tumor suppressor responses

The pathogenesis of incipient Alzheimer's disease (AD) has been resistant to analysis because of the complexity of AD and the overlap of its early-stage markers with normal aging. Gene microarrays provide new tools for addressing complexity because they allow overviews of the simultaneous activity of multiple cellular pathways. However, microarray data interpretation is often hindered by low statistical power, high false positives or false negatives, and by uncertain relevance to functional endpoints. Here, we analyzed hippocampal gene expression of nine control and 22 AD subjects of varying severity on 31 separate microarrays. We then tested the correlation of each gene's expression with MiniMental Status Examination (MMSE) and neurofibrillary tangle (NFT) scores across all 31 subjects regardless of diagnosis. These well powered tests revealed a major transcriptional response comprising thousands of genes significantly correlated with AD markers. Several hundred of these genes were also correlated with AD markers across only control and incipient AD subjects (MMSE > 20). Biological process categories associated with incipient AD-correlated genes were identified statistically (ease program) and revealed up-regulation of many transcription factor/signaling genes regulating proliferation and differentiation, including tumor suppressors, oligodendrocyte growth factors, and protein kinase A modulators. In addition, up-regulation of adhesion, apoptosis, lipid metabolism, and initial inflammation processes occurred, and down-regulation of protein folding/metabolism/transport and some energy metabolism and signaling pathways took place. These findings suggest a new model of AD pathogenesis in which a genomically orchestrated up-regulation of tumor suppressor-mediated differentiation and involution processes induces the spread of pathology along myelinated axons.