Altered content and distribution of tenascin in colitis, colon adenoma, and colorectal carcinoma

Tenascin-C is a driver of inflammation in the DSS model of colitis

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Increased tenascin-C staining appeared to predominantly occur in damaged ulcerated areas.

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Tenascin-C knock-out mice were partly protected from DSS induced colitis.

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Mice deficient in tenascin-C had areas of + ve EpCAM staining indicating that crypt and epithelial integrity was maintained.

Inflammatory Bowel Disease (IBD) is a grouping of chronic inflammatory disorders of the gut. Tenascin-C is a pro-inflammatory, extracellular matrix protein found upregulated in IBD patients and whilst a pathological driver of chronic inflammation, its precise role in the etiology of IBD is unknown. To study tenascin-C’s role in colitis pathology we investigated its expression in a murine model of IBD. Wild-type (WT) or tenascin-C knockout (KO) male mice were left untreated or treated with dextran sodium sulphate (DSS) in their drinking water. Tenascin-C was upregulated at the mRNA level in the colitic distal colon of day eight DSS treated mice, coinciding with significant increases in gross and histological pathology. Immunohistochemistry localized this increase in tenascin-C to areas of inflammation and ulceration in the mucosa. Tenascin-C KO mice exhibited reduced gross pathology in comparison. These differences also extended to the histopathological level where reduced colonic inflammation and tissue damage were found in KO compared to WT mice. Furthermore, the severity of the distal colon lesions were less in the KO mice after 17 days of recovery from DSS treatment. This study demonstrates a role for tenascin-C as a driver of inflammatory pathology in a murine model of IBD and thus suggests neutralizing its pro-inflammatory activity could be explored as a therapeutic strategy for treating IBD.

A Holistic Appraisal of Stromal Differentiation in Colorectal Cancer: Biology, Histopathology, Computation, and Genomics

Cancer comprises epithelial tumor cells and associated stroma, often times referred to as the "tumoral microenvironment". Cancer-associated fibroblasts (CAFs) are the most notable components of the tumor mesenchyme. CAFs promote the initiation of cancer through angiogenesis, invasion and metastasis. Histologically, the differentiation of stroma has been reported to correlate with prognostic outcomes in patients with colorectal cancer. This review summarizes our current understanding of the extracellular matrix (ECM) in colorectal carcinoma (CRC), showcasing the functions of CAFs and its role in stromal differentiation (SD). We also review current state-of-the-art biology, histopathology, computation, and genomics in the setting of the stroma. SD is distinctive morphologically, and is easily recognized by a surgical pathologist; we offer a lexicon and guide for discovering the essence of stroma, as well as an incipient vision of the future for computation and molecular genomics. We propose that the mesenchymal phenotype, which encompasses a cancer migratory/metastatic capacity, could occur through the process of SD. Looking forward, pathologists will need to invest time and energy into SD, embracing the concept and propagating its use. For patients with colorectal cancer, stroma is a brave new frontier, one not only rich in biologic diversity, but also potentially critical for therapeutic decision making.

The laminin response in inflammatory bowel disease: protection or malignancy?

Laminins (LM), basement membrane molecules and mediators of epithelial-stromal communication, are crucial in tissue homeostasis. Inflammatory Bowel Diseases (IBD) are multifactorial pathologies where the microenvironment and in particular LM play an important yet poorly understood role in tissue maintenance, and in cancer progression which represents an inherent risk of IBD. Here we showed first that in human IBD colonic samples and in murine colitis the LMα1 and LMα5 chains are specifically and ectopically overexpressed with a concomitant nuclear p53 accumulation. Linked to this observation, we provided a mechanism showing that p53 induces LMα1 expression at the promoter level by ChIP analysis and this was confirmed by knockdown in cell transfection experiments. To mimic the human disease, we induced colitis and colitis-associated cancer by chemical treatment (DSS) combined or not with a carcinogen (AOM) in transgenic mice overexpressing LMα1 or LMα5 specifically in the intestine. We demonstrated that high LMα1 or LMα5 expression decreased susceptibility towards experimentally DSS-induced colon inflammation as assessed by histological scoring and decrease of pro-inflammatory cytokines. Yet in a pro-oncogenic context, we showed that LM would favor tumorigenesis as revealed by enhanced tumor lesion formation in both LM transgenic mice. Altogether, our results showed that nuclear p53 and associated overexpression of LMα1 and LMα5 protect tissue from inflammation. But in a mutation setting, the same LM molecules favor progression of IBD into colitis-associated cancer. Our transgenic mice represent attractive new models to acquire knowledge about the paradoxical effect of LM that mediate either tissue reparation or cancer according to the microenvironment. In the early phases of IBD, reinforcing basement membrane stability/organization could be a promising therapeutic approach.

Inflammation-induced endothelial-to-mesenchymal transition: a novel mechanism of intestinal fibrosis

In addition to mesenchymal cells, endothelial cells may contribute to fibrosis through the process of endothelial-to-mesenchymal transition (EndoMT). We investigated whether human intestinal microvascular endothelial cells (HIMEC) undergo EndoMT and contribute to fibrosis in human and experimental inflammatory bowel disease (IBD). HIMEC were exposed to TGF-β1, IL-1β, and TNF-α or supernatants of lamina propria mononuclear cells (LPMC) and evaluated for morphological, phenotypic, and functional changes compatible with EndoMT. Genomic analysis was used to identify transcription factors involved in the transformation process. Evidence of in situ and in vivo EndoMT was sought in inflamed human and murine intestine. The combination of TGF-β1, IL-1β and TNF-α, or activated LPMC supernatants induced morphological and phenotypic changes consistent with EndoMT with a dominant effect by IL-1. These changes persisted after removal of the inducing agents and were accompanied by functional loss of acetylated LDL-uptake and migratory capacity, and acquisition of de novo collagen synthesis capacity. Sp1 appeared to be the main transcriptional regulator of EndoMT. EndoMT was detected in microvessels of inflammatory bowel disease (IBD) mucosa and experimental colonic fibrosis of Tie2-green fluorescent protein (GFP) reporter-expressing mice. In conclusion, chronic inflammation induces transdifferentiation of intestinal mucosal microvascular cells into mesenchymal cells, suggesting that the intestinal microvasculature contributes to IBD-associated fibrosis through the novel process of EndoMT.

Inflammation-induced endothelial-to-mesenchymal transition: a novel mechanism of intestinal fibrosis

In addition to mesenchymal cells, endothelial cells may contribute to fibrosis through the process of endothelial-to-mesenchymal transition (EndoMT). We investigated whether human intestinal microvascular endothelial cells (HIMEC) undergo EndoMT and contribute to fibrosis in human and experimental inflammatory bowel disease (IBD). HIMEC were exposed to TGF-β1, IL-1β, and TNF-α or supernatants of lamina propria mononuclear cells (LPMC) and evaluated for morphological, phenotypic, and functional changes compatible with EndoMT. Genomic analysis was used to identify transcription factors involved in the transformation process. Evidence of in situ and in vivo EndoMT was sought in inflamed human and murine intestine. The combination of TGF-β1, IL-1β and TNF-α, or activated LPMC supernatants induced morphological and phenotypic changes consistent with EndoMT with a dominant effect by IL-1. These changes persisted after removal of the inducing agents and were accompanied by functional loss of acetylated LDL-uptake and migratory capacity, and acquisition of de novo collagen synthesis capacity. Sp1 appeared to be the main transcriptional regulator of EndoMT. EndoMT was detected in microvessels of inflammatory bowel disease (IBD) mucosa and experimental colonic fibrosis of Tie2-green fluorescent protein (GFP) reporter-expressing mice. In conclusion, chronic inflammation induces transdifferentiation of intestinal mucosal microvascular cells into mesenchymal cells, suggesting that the intestinal microvasculature contributes to IBD-associated fibrosis through the novel process of EndoMT.

Degeneration of the pericryptal myofibroblast sheath by proinflammatory cytokines in inflammatory bowel diseases

BACKGROUND & AIMS

Inflammatory bowel diseases (IBDs) are characterized by remodeling of the intestinal mucosa, which is associated with excessive cytokine release. Previous studies have shown that the epithelium in the crypt region of the mucosa in patients with Crohn's disease is susceptible to proinflammatory cytokines. We investigated whether the subepithelial myofibroblasts in this region were affected by these inflammatory conditions.

METHODS

Immunofluorescence and immunohistochemistry were performed on inflamed and uninflamed specimens from patients with IBD to detect alpha-smooth muscle actin (alphaSMA), desmin, and tenascin-C. The effects of the proinflammatory cytokines interleukin-1beta, tumor necrosis factor-alpha, and interferon-gamma were analyzed in human intestinal myofibroblast cultures by immunoblotting and apoptosis assays.

RESULTS

Immunofluorescence analysis revealed decreased levels of the extracellular matrix molecule tenascin-C in pericryptal sheaths and alphaSMA in the immediate vicinity of the crypts in the inflamed specimens, indicating that the myofibroblast pericryptal sheath is affected by proinflammatory cytokines. Although individual cytokines did not affect myofibroblast proliferation or survival, cytokine combinations triggered caspase-dependent apoptosis. alphaSMA levels were reduced significantly in cells exposed to cytokines, either alone or in combination, suggesting dedifferentiation of myofibroblasts. Proinflammatory cytokines did not affect tenascin-C expression, suggesting that the decrease observed in the inflamed mucosa resulted from myofibroblast apoptosis.

CONCLUSIONS

The subepithelial myofibroblasts of the epithelial sheath are disrupted in the intestinal mucosa of patients with IBD. A loss of myofibroblasts appears to result from the susceptibility of these cells to proinflammatory cytokines.

Tenascin-C expression and its prognostic significance in colorectal cancer

OBJECTIVE

The extracellular matrix glycoprotein tenascin-C has been proposed as a tumor marker with prognostic significance in many cancer forms, but in colorectal cancer, reported results have been controversial. The aim of this study was to evaluate the prognostic value of immunohistochemical tenascin-C expression in a series of 231 patients with colorectal cancer.

METHODS

Paraffin-embedded formalin-fixed specimens were stained with a tenascin-C-specific monoclonal antibody, and the stromal staining intensity and pattern were analyzed.

RESULTS

Tenascin-C immunoreactivity was observed in all 231 specimens, with a pattern of staining that was diffuse and interstitial. The staining was occasional in 39 (17%), moderate in 106 (46%) and strong in 86 specimens (37%). There was no statistically significant association between tenascin-C immunoreactivity and any of the other clinicopathological variables. The cumulative 5-year survival rates of patients with occasional and weak staining were similar (56.8 and 54.9%, respectively), while the patients with strong tenascin-C staining had a lower survival rate (46.1%). This difference in survival was not significant (p = 0.23). The staining pattern and distribution can be viewed from digitized representative microscope slides (virtual slides) at http://www.webmicroscope.net/supplements/tenascin.

CONCLUSIONS

Our results indicate that immunohistochemical expression of tenascin-C is not of prognostic significance in colorectal cancer.

Tenascin C and annexin II expression in the process of pancreatic carcinogenesis

Tenascin C (TNC) is a component of the provisional extracellular matrix (ECM) that characterizes solid tumours. Cell surface annexin II is a high-affinity receptor for large TNC splice variants. The aim of this study was to analyse whether TNC and annexin II play a role in the development of pancreatic ductal adenocarcinoma (PDAC). PDAC is characterized by a rich ECM populated by pancreatic stellate cells, which play a crucial role in pancreatic desmoplasia. The mRNA and protein levels of TNC and of annexin II were analysed in pancreatic tissues by DNA array, quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) and immunohistochemistry. TNC large splice variants were detected by RT-PCR. Enzyme linked immunosorbent assay (ELISA) was used to measure TNC levels in serum and culture supernatants. TNC and annexin II mRNA levels were significantly higher in pancreatic cancer tissues than in the normal pancreas. TNC expression was detected with increased frequency in the progression from PanIN-1 lesions to PDAC, and a parallel switch from cytoplasmic to cell surface expression of annexin II was observed. Large TNC transcripts were found in pancreatic cancer and in chronic pancreatitis, but not in the normal pancreas. TNC expression was demonstrated in pancreatic stellate cells, where it could be induced by tumour necrosis factor alpha (TNFalpha), transforming growth factor beta1 (TGF-beta1) and by cancer cell supernatants supplemented with TGF-beta1. In conclusion, the expression of TNC and cell surface annexin II increases in the progression from low-grade PanIN lesions to pancreatic cancer. Pancreatic stellate cells are identified as a source of TNC in pancreatic tissues, possibly under the influence of soluble factors released by the tumour cells.

Analysis of structure and function of tenascin-C

Tenascin-C is a multidomain large extracellular matrix glycoprotein composed of six monomers. The size of tenascin-C monomers (180-250 kDa) varies as a result of an alternative splicing of the fibronectin repeats at the pre-mRNA level. For the first time we applied bioinformatic and molecular modeling procedures, for detailed analysis of the organization of tenascin-C and we performed bioinformatic analysis of tenascin-C gene. We detected the presence of heat shock protein 33 in the tenascin-C N-terminal domain that may suggest its role in the protein-protein interactions and stress response. The number of fibronectin type III-like repeats and epidermal growth factor-like repeats were corrected to 15 and 14, respectively. Using polyactylamide gel electophoresis, RT/PCR analysis and microarrays data, we showed the higher level of tenascin-C in the human tumor tissues: brain, intestine and breast. These results suggested a new role of tenascin-C as the potential tumor marker and drug target.

Latent effects of fibronectin, alpha5beta1 integrin, alphaVbeta5 integrin and the cytoskeleton regulate pancreatic carcinoma cell IL-8 secretion

Interactions between tumour cells and the microenvironment are increasingly recognised to have an influence on cancer progression. In pancreatic carcinoma, a highly desmoplastic stroma with abnormal extracellular matrix (ECM) protein and interleukin-8 (IL-8) expression is seen. To investigate whether the ECM may further contribute to abnormalities in the microenvironment by influencing IL-8 secretion, we cultured the Mia PaCa2 pancreatic carcinoma cell line on fibronectin. This resulted in a dose-dependent increase in IL-8 secretion, which was RGD dependent and accompanied by cell spreading and proliferation. The role of spreading was assessed by disruption of the cytoskeleton with cytochalasin D, resulting in a large increase in IL-8 secretion, which was reduced from 31- to 24-fold by fibronectin. This remarkable response was associated with inhibition of spreading and proliferation and represents a novel cytoskeletal function. To investigate whether it could be accounted for by the loss of integrin-mediated signalling, the expressed α5β1, αVβ5 and α3β1 integrins were inhibited. α5β1 inhibition prevented spreading and proliferation but produced a much smaller rise in IL-8 secretion than cytochalasin D. αVβ5 inhibition alone had only minor effects but when inhibited in combination with α5β1 completely abolished the response to fibronectin. These results reveal latent stimulatory effects of the αVβ5 integrin on IL-8 secretion and suggest that integrin crosstalk may limit the induction of IL-8 secretion by fibronectin. However, the magnitude of IL-8 secretion induced by cytochalasin cannot be accounted for by integrin signalling and may reflect the influence of another signalling pathway or a novel, intrinsic cytoskeletal function.

Tenascin-C and SF/HGF produced by myofibroblasts in vitro provide convergent pro-invasive signals to human colon cancer cells through RhoA and Rac

Myofibroblasts are present at the invasion front in colon cancer. In an attempt to understand their putative proinvasive activity, we have developed an in vitro model. Myofibroblasts isolated from colon cancer tissue or obtained through transdifferentiation of colon fibroblasts by transforming growth factor (TGF)-beta stimulate invasion of colon cancer cells into collagen type I and Matrigel. We identified two convergent proinvasive agents secreted by myofibroblasts: namely scatter factor/hepatocyte growth factor (SF/HGF) and the TGF-beta-upregulated extracellular matrix glycoprotein tenascin-C (TNC), each of which is necessary though not sufficient for invasion. Myofibroblast-stimulated invasion into collagen type I is characterized by a change from a round, nonmigratory morphotype with high RhoA and low Rac activity to an elongated, migratory morphotype with low RhoA and high Rac activity. RhoA inactivation is determined by the epidermal growth factor (EGF)-like repeats of TNC through EGF-receptor signaling that confers a permissive and priming signal for the proinvasive activity of SF/HGF that activates Rac via c-Met. We confirmed the validity of this mechanism by using pharmacological modulators and dominant negative or constitutive active mutants that interfere with RhoA-Rho kinase and Rac signaling. Our in vitro results point to a new putative proinvasive signal for colon cancer cells provided by myofibroblasts in the tumor stroma.

Tenascin expression in relation to stromal tumour cells in canine gastrointestinal epithelial tumours

The expression of tenascin, alpha-smooth muscle actin (alpha-SMA), desmin and vimentin was investigated immunohistochemically in the stroma of normal canine stomach, small intestine and colon, and in 30 epithelial tumours of the canine stomach, small intestine or colon. In addition, "co-localization" of tenascin and alpha-SMA was investigated by double immunohistochemistry. Tenascin was absent in the normal gastric mucosa but present in the normal intestine, with a gradual increase in immunolabelling intensity from the cryptal glands to the surface epithelium. Tenascin expression was greater in all adenomas and carcinomas than in normal tissues. Two different patterns of tenascin expression were observed in all carcinomas, irrespective of their site. In well-differentiated tumour regions of both gastric and intestinal tumours, a fibrillary sub-glandular expression was observed; in poorly differentiated tumour regions, however, the expression pattern was diffuse. Incomplete invasion of the muscularis mucosae was accompanied by thickening and increased tenascin expression. In normal stomach and intestines, alpha-SMA and desmin were demonstrated in pericryptal myofibroblasts and smooth muscle cells of the muscle layers. In colonic adenomas and gastric and intestinal carcinomas, alpha-SMA was demonstrated in all stromal cells surrounding tumour cells. In contrast to alpha-SMA labelling, desmin labelling was negative in tumour stromal cells (in both gastric and intestinal tumours), except in tumour regions close to the muscularis mucosae. This suggested that myofibroblasts in gastric and intestinal tumours originated from pre-existing fibroblasts, except in tumour regions close to the muscularis mucosae, where the myofibroblasts seemed to originate from smooth muscle cells of the muscularis mucosae. There was a strong co-localization of tenascin and alpha-SMA-expressing myofibroblasts, suggesting that myofibroblasts are responsible for tenascin secretion.

Subepithelial myofibroblasts and tenascin expression in microscopic colitis

AIMS

To assess differences in the pattern of subepithelial myofibroblasts and the expression of tenascin as a marker of extracellular matrix production in collagenous and lymphocytic colitis.

METHODS AND RESULTS

Colorectal biopsies were studied from 122 patients with chronic diarrhoea and normal colonoscopy. The pathological diagnoses were collagenous colitis (n = 35), lymphocytic colitis (n = 37), mild non-specific chronic inflammation (n = 28) and normal mucosa (n = 18). Four cases showed features of collagenous colitis but with collagen bands <10 micro m thick. Normal mucosa from 14 patients without diarrhoea served as healthy control tissue. Immunohistochemical expression of alpha-smooth muscle actin (myofibroblast marker) and tenascin was evaluated in well-orientated sections. The expression of alpha-smooth muscle actin was significantly increased in collagenous colitis compared with all the other groups. Strong tenascin subepithelial expression was seen in all cases of collagenous colitis, including the four without full-blown features. The mean thickness of tenascin bands was greater than that obtained by conventional stains.

CONCLUSIONS

There are clear differences, with respect to extracellular matrix remodelling, between collagenous and lymphocytic colitis. These results support the theory of matrix overproduction in the genesis of collagenous colitis.

Progress on isolation and short-term ex-vivo culture of highly purified non-apoptotic human intestinal epithelial cells (IEC)

Intestinal epithelial cells (IEC) form the largest surface of the human body and are of pivotal importance to digest and absorb nutrients. Furthermore these cells play a critical role shielding the organism against microorganisms and toxins present in the intestinal lumen. It is therefore not surprising that a large group of researchers take great interest in the study of these cells. However, to date it is a challenge to purify viable primary human intestinal epithelial cells and it has been even more fastidious to maintain IEC in culture ex-vivo as IEC undergo apoptosis within hours due to loss of cell anchorage ('anoikis') following the isolation process. Over recent years the authors aimed to continuously improve the isolation technique for primary IEC, allowing a simple, effective and rapid isolation of highly purified non-apoptotic human IEC. In this study the newly improved method is presented and applied to establish ex-vivo cultures of highly purified, fully viable primary IEC displaying important functional properties, making these cells amenable for ex-vivo research on primary human intestinal epithelial cells.

The alpha2 and alpha3 integrins are required for morphologic differentiation of an intestinal epithelial cell line

BACKGROUND

The molecular mechanisms controlling intestinal epithelial cell differentiation are poorly defined because of the difficulty of growing normal intestinal cells. We have taken advantage of the ability of the Caco-2 cell line to acquire a glandular phenotype in 3-dimensional (3-D) culture systems to investigate the role of alpha2 and alpha3 integrins in morphologic differentiation.

METHODS

Caco-2 cells transfected with sense or antisense DNA constructs of alpha2 or alpha3 integrins were grown in 3-D Matrigel or collagen I in the presence or absence of integrin function-blocking antibodies. We used light and confocal microscopy, BrDU incorporation, TUNEL assay, a fluorometric adhesion assay, FACS analysis, and Western blot analysis to study the effect of extracellular matrix (ECM) and integrins on morphology, polarization, proliferation, apoptosis, cell adhesion, and integrin expression.

RESULTS

Compared to collagen I, Caco-2 cells cultured in 3-D Matrigel display cytoskeletal and adherens junction rearrangements and decreased proliferation consistent with cellular differentiation. These changes, which are inhibited by alpha2 and alpha3 blocking monoclonal antibodies and alpha2 and alpha3 antisense DNA transfection, were associated with an increase in alpha3 integrin expression.

CONCLUSIONS

We demonstrated that signaling through both constitutively expressed alpha2 integrin and Matrigel-induced alpha3 integrin expression is required to acquire a differentiated phenotype in Caco-2 cells.

Interaction of nitric oxide and cell adhesion molecules after 24 hours of complete ureteric obstruction in the rats on a solitary kidney

We aimed to show whether the administration of exogenous L-Arg would alter the morphological, functional changes and interaction of nitric oxide and cell adhesion molecules such as tenascin and lectin after release of twenty-four hours complete ureteric obstruction in the solitary rat kidney tissue. Forty prepubertal Wistar-Albino rats were separated into 4 groups, each containing 10 rats. In the group 1 (Sham-control, n = 10), right nefrectomy was performed; the left ureter was visualized but not ligated. In the remaining 30 rats, the abdomen was opened and undergone right nephrectomy and the left ureter was completely obstructed. After 24 hours, thirty rats were divided as group 2, 3, and 4, each containing 10 rats. In-group 2, no drug treatments were given. In-group 3 L-Arg (L-arginine methyl ester) was infused immediately after abolishing ureteric obstruction. In-group 4 L-NAME was give separately during L-Arg administration during 30 minutes immediately after abolishing ureteric obstruction. Than, the animals were prepared for functional and histopathological studies. BUN value was decreased significantly in L-Arg group when compared with untreatment and L-NAME groups (p < 0.05, p < 0.001 respectively). Creatinine values were decreased in L-Arg group when compared with untreatment group (p < 0.002). Urine flow and urinary Na value was increased significantly in L-Arg group when compared to other obstruction groups (p < 0.001, p < 0.001). The increase in the number of macrophages in Untreated and L-NAME group were significant (p < 0.001, p < 0.001) when compared to L-Arg group. Immunohistochemical study showed that tenascin and lectin expression was severe in tubulus basal membrane of untreated and L-NAME treated rats. In L-Arg group, tenascin and lectin expression was moderate in tubulus membrane. Our results suggest that the administration of exogenous L-Arg protect the functional and degenerative effects of acute complete obstruction in the solitary kidney tissue of the rats. Nitric oxide cause these positive effects by decreasing preglomerular vascular resistance, regulation of neutrophil function and preventing the expression of cell adhesion molecules such as tenascin and lectin.

Induction of apoptosis before shedding of human intestinal epithelial cells

OBJECTIVES

Human intestinal epithelial cells (IECs) derive from stem cells at the crypt base and migrate along the so-called crypt-villus axis toward the intestinal lumen. As they reach the luminal surface in the colon or the villus tip in the small intestine, IECs are shed and their life cycle is terminated. The role of apoptosis during IEC migration along the crypt-villus axis has been subject to studies with conflicting results. In this study we use a novel approach to identify the initiation of apoptosis within normal human IECs.

METHODS

Normal mucosa from the large and small human intestine was analyzed employing a novel antibody directed against activated caspase-3--an early marker of apoptosis.

RESULTS

IECs initiate the apoptotic cascade as they approach the area of shedding before displaying evident morphological features of apoptosis. IECs of the small bowel also show caspase-3 activation in the small intestinal crypt base, whereas IECs of the colononic crypt base rarely show evidence of ongoing apoptosis.

CONCLUSIONS

These findings indicate that apoptosis is initiated in human IECs as they reach the luminal surface/villus tip and before shedding. Furthermore, they show that different sections of the intestinal tract vary significantly in the rate of IEC apoptosis, possibly reflecting their difference in susceptibility to epithelial cell neoplasia.

Tenascin and strictures in inflammatory bowel disease: an immunohistochemical study

Tenascin is an extracellular matrix protein involved in morphogenesis of muscle tissue and in wound healing. In the present study we examined its distribution in tissue from patients with inflammatory bowel disease. Intestinal biopsies from 10 normal controls, 15 patients with Crohn's disease, and 6 with ulcerative colitis were studied. Samples were obtained both from uninvolved and involved areas. Mucosal tenascin is increased in ulcerative colitis and Crohn's disease, especially in areas of ulceration. In Crohn's disease, tenascin is also strongly expressed in the submucosa and in smooth muscle cells of the muscularis mucosae and propria, especially in areas of stricture. We conclude that tenascin is involved in stricture formation in Crohn's disease and that it is a marker of phenotypic change in smooth muscle cells.

Unaltered distribution of laminins, fibronectin, and tenascin in celiac intestinal mucosa

Extensive remodeling of the extracellular matrix (ECM) occurs in inflammatory tissues. The celiac lesion in the small intestine is characterized by inflammation accompanied by profound morphological alterations. We used immunohistochemistry to determine the distribution of laminin, fibronectin, and tenascin isoforms in small intestinal biopsies of untreated patients with celiac disease. In normal mucosa, the distribution of laminin isoforms defines three epithelial basement membrane (BM) zones. We found that the organization of these zones was maintained in the celiac mucosa. Thus, components of laminin-5 (alpha3 and beta3) were found in the surface epithelial BM, laminin alpha2 chain was found selectively at crypt bottoms, and laminin alpha5 chain was the sole alpha-type chain in middle crypt BMs. Likewise, the distribution of fibronectin and tenascin resembled that of the normal gut. The organization of pericryptal fibroblasts and lamina propria smooth muscle strands, as defined by immunostaining for alpha-smooth muscle actin, also remained unchanged in the celiac mucosa. Unexpectedly, major ECM changes were not detected in the celiac lesion.

Characteristic distribution patterns of tenascin in laryngeal and hypopharyngeal cancers

OBJECTIVES

Progression of malignant neoplasias is accompanied by alteration of the extracellular matrix (ECM) composition. Tenascin is known as a member of the adhesion-modulating family of ECM macromolecules; thus its expression and distribution may have significant influence on tumor cell proliferation and invasiveness.

STUDY DESIGN

The present study was carried out to determine the distribution pattern of tenascin in laryngeal and hypopharyngeal cancer samples.

METHODS

In double and triple immunofluorescent staining reactions the detection of tenascin was combined with labelings for cytokeratin (marker protein of epithelial cells), for CD-34 (endothelial cell surface glycoprotein), and for a reaction with Ki-67 monoclonal antibody (nuclear antigen in proliferating cells).

RESULTS

In laryngeal cancers, in early stages of tumor growth a markedly enhanced production of tenascin at the tumor host interphase was observed. In the later stages of tumor progression, a high number of blood vessels located in the tumorous tissues were also strongly labeled for tenascin. Around these vessels a significant number of proliferating tumor cells could be detected. In contrast, in hypopharyngeal cancers this vasculature-associated staining pattern could be observed from the very early stage of tumor development. In laryngeal and in hypopharyngeal cancers, tenascin upregulation strongly correlated with metastasis formation, early tumor recurrence, and lethal outcome of the disease.

CONCLUSIONS

Clinical and immunohistologic data indicate that the accumulation of tenascin in the tumor blood vessels is an unfavorable prognostic indicator in laryngeal and hypopharyngeal cancers.

Caco-2 cells and human fetal colon: a comparative analysis of their lipid transport

Caco-2 cells and human colonic explants were compared for their ability to esterify lipid classes, synthesize apolipoproteins and assemble lipoproteins. Highly differentiated cells and colonic explants were incubated with [(14)C]oleic acid or [(35)S]methionine for 48 h. Caco-2 cells demonstrated a higher ability to incorporate [(14)C]oleic acid into cellular phospholipids (13-fold, P<0.005), triglycerides (28-fold, P<0.005) and cholesteryl ester (2-fold, P<0. 01). However, their medium/cell lipid ratio was 11 times lower, indicating a limited capacity to export newly synthesized lipids. De novo synthesis of apo B-48 and apo B-100 was markedly increased (7%0 and 240%, respectively), whereas the biogenesis of apo A-I was decreased (60%) in Caco-2 cells. The calculated apo B-48/apo B-100 ratio was substantially diminished (107%), suggesting less efficient mRNA editing in Caco-2 cells. When lipoprotein distribution was examined, it displayed a prevalence of VLDL and LDL, accompanied along with a lower proportion of chylomicron and HDL. In addition, differences in lipoprotein composition were evidenced between colonic explants and Caco-2 cells. Therefore, our findings stress the variance in the magnitude of lipid, apolipoprotein and lipoprotein synthesis and secretion between the two intestinal models. This may be due to various factors, including the origin of Caco-2 cell line, i.e., colon carcinoma.

Detection of tenascin-C isoforms in colorectal mucosa, ulcerative colitis, carcinomas and liver metastases

The glycoprotein tenascin-C is up-regulated in inflammatory and neoplastic diseases. Most available data on tissue tenascin-C content do not distinguish its various isoforms. We have quantified tissue tenascin-C signals in colorectal mucosa, ulcerative colitis, colorectal carcinomas and liver metastases using 5 monoclonal antibodies (MAbs) with different binding sites. Tenascin-C of tissue extracts was analyzed by a standardized Western blot technique and densitometry. As a reference MAb, K8 displayed tenascin-C tissue concentrations of 4.1 +/- 2.3 microgram/mg total protein in normal mucosa, 13.8 +/- 4.7 microgram/mg in ulcerative colitis, 28.8 +/- 14.5 microgram/mg in colorectal carcinomas and 25.6 +/- 8.9 microgram/mg in liver metastases. The optical density values per microgram protein tissue extract of the 5 MAbs reflect the levels of the corresponding tenascin-C epitopes. Various signal intensities indicate a distinct diagnostic usefulness of the MAbs in detecting colorectal carcinomas. The binding characteristics of MAb J1/tn2 point to an under-representation of the TNfnD domain in metastasizing colorectal carcinomas, while MAb 19H12 showed an increased binding rate on the TNfnA1,2,4 region. Our comparative study of tenascin-C in inflammatory and neoplastic diseases of the colon mucosa substantiates the occurrence of large differences in the diagnostic value of tenascin-C MAbs. The detected alterations of tenascin-C in metastasizing colorectal carcinomas might indicate a prognostic value of specific tenascin-C isoforms.

Tenascin labelling in colorectal biopsies: a useful marker in the diagnosis of collagenous colitis

AIMS

This study was undertaken to clarify whether immunohistological detection of tenascin (TN), an extracellular matrix glycoprotein that is expressed during stromal remodelling, may allow a more precise diagnosis of collagenous colitis.

METHODS AND RESULTS

We studied multiple colorectal biopsies specimens from 15 patients with clinically suspected collagenous colitis for TN expression by using a monoclonal antibody. Biopsies from further 15 patients without symptoms and signs of collagenous colitis served as controls. In seven of the 15 cases with clinically suspected collagenous colitis a prominent and selective subepithelial tenascin expression was identified. The TN expression pattern closely correlated with the conventional detection of a subepithelial collagen band diagnostic of collagenous colitis. The immunohistological labelling for TN allowed a quicker and more precise measurement of the thickness of the diagnostic collagen deposits than conventional staining. By this approach one further case could be reclassified as collagenous colitis.

CONCLUSIONS

Our data show that immunohistological detection of TN allows a more correct and easy diagnosis of collagenous colitis.

Expression of tenascin-C in intraductal carcinoma of human breast: relationship to invasion

Tenascin-C (Tn-C) is an extracellular matrix glycoprotein that appears in areas of epithelial-mesenchymal interaction during fetal development and in neoplasia. The immunohistochemical expression of Tn-C and its relationship to histology, nuclear grade, microinvasion, oestrogen (ER) and progesterone receptors (PR), and to cell proliferation measured by Ki-67 expression were studied in 89 intraductal breast carcinomas (DCIS). Periductal Tn-C was noted in 87% and stromal Tn-C in 25% of the tumours. Stromal expression was associated with moderate to strong periductal expression and microinvasion. Periductal expression was associated with comedo-type, nuclear grade, microinvasion, Ki-67 expression, and lack of PR. The distribution of Tn-C was compared in DCIS and in the intraductal component from another series of small axillary node-negative invasive breast carcinomas (n = 44). Tn-C was present in the stroma of pure DCIS in 25% and in the intraductal component of the other series in 82%. Thus, stromal or moderate to strong periductal Tn-C expression in DCIS may relate to early invasion. DCIS with weak periductal or missing Tn-C expression may be a subgroup with benign behaviour.

Sequential and rapid activation of select caspases during apoptosis of normal intestinal epithelial cells

Detachment-induced cell death (DICD) is considered to be one of the means by which intestinal epithelial cells (IEC) die of apoptosis as they reach the lumen and are shed. Caspases, a family of cysteine proteases, play a central role in initiating, amplifying, and executing apoptosis; however, the pattern of caspase activation in response to distinct apoptotic stimuli remains unknown. We investigated the kinetics of caspase activation during DICD in freshly isolated human IEC. DNA fragmentation is observed 90 min after detachment and is preceded by the sequential activation of preformed members of the CPP32 family of caspases. Activation of caspase 6 and cleavage of the endogenous caspase substrate poly(ADP-ribose) polymerase (EC 2.4.2.30) are detected within 15 min of detachment, 30-45 min before caspase 3 activation. Caspase 1 and caspase 10 are present as proenzymes, yet they remain inactive in response to this trigger of apoptosis. Human IEC are primed to rapidly undergo detachment-induced apoptosis involving the selective and sequential activation of preformed caspases. This study may enhance our understanding of physiological events occurring as IEC are shed. Their rapid apoptotic response to detachment may facilitate the high turnover of cells and ensure homeostasis in the intestinal epithelium.

Mucosal tenascin C content in inflammatory and neoplastic diseases of the large bowel

PURPOSE

Tenascin C is a glycoprotein of the extracellular matrix. It is upregulated during embryologic development, wound healing, and under conditions of normal and neoplastic growth. Most available data on tenascin C expression in tissues is based on immunohistologic studies. The present study was designed to quantify tissue concentrations in patients with inflammatory and neoplastic diseases of the large bowel.

METHODS

Fifty patients with ulcerative colitis, 19 patients suffering from familiar adenomatous polyposis without malignant transformation, and 69 patients with colorectal carcinoma were investigated. Tenascin C concentrations in tissue extracts were determined by semiquantitative Western blotting.

RESULTS

The tenascin C tissue concentration of normal mucosa was 2.6 +/- 3.4 microg/mg (n = 55), 2.9 +/- 2.1 microg/mg in colorectal adenomas (n = 19), 7.5 +/- 4.7 microg/mg in ulcerative colitis (n = 50), and 18 +/- 15 microg/mg in colorectal carcinomas (n = 69; mean +/- standard deviation). In ulcerative colitis, the mucosal tenascin C content correlated with histopathologic disease activity. No differences were found between subgroups of adenomas or carcinomas.

CONCLUSIONS

Tenascin C tissue concentrations were not altered in adenomas, slightly elevated in ulcerative colitis, and substantially increased in colorectal carcinomas. Although less useful as a diagnostic parameter, tenascin C tissue levels serve as an instrument for assessing the activity of stromal remodeling in large-bowel diseases generally. Specifically, they may reflect disease activity in ulcerative colitis.

Expression of tenascin in lymphocytic autoimmune thyroiditis

AIMS

To study the distribution of tenascin by immunocytochemistry in autoimmune diseases of the thyroid.

METHODS

Thyroids from patients with inflammatory lesions of the thyroid (lymphocytic thyroiditis Hashimoto, Grave's disease, thyroiditis DeQuervain) were studied by immunocytochemistry using antibodies against tenascin, collagen III, and collagen IV.

RESULTS

In autoimmune lymphocytic thyroiditis Hashimoto there was a characteristic corona-like staining pattern of tenascin around all activated lymph follicles with germinal centres. This staining pattern contrasted with the immunoreactions for collagen III and IV, which were not enhanced in the perilymphofollicular interstitium. In cases of thyroiditis DeQuervain the areas of early and ongoing fibrosis showed some diffuse staining for tenascin and for collagen III. Enhanced diffuse immunostaining for collagen IV in the perivascular and interfollicular interstitium was present in cases of Grave's disease. In Grave's disease no characteristic immunoreaction was detectable for tenascin.

CONCLUSIONS

The corona-like expression of tenascin around lymphofollicular infiltrates is distinctive of cases of lymphocytic thyroiditis. A similar staining pattern for tenascin has been reported in lymphoid hyperplasia of the thymus associated with myasthenia gravis, another autoimmunological disorder. There are good arguments that the activation and infiltration of lymph follicles in the thyroid during the course of autoimmune diseases lead to stimulation and activation of the surrounding mesenchyme producing tenascin as part of the extracellular matrix.

Expression of fibronectin and tenascin-C mRNA by myofibroblasts, vascular cells and epithelial cells in human colon adenomas and carcinomas

To understand the mechanisms of tissue remodeling during cancer progression, it is important to know the type of cells that actively express extracellular matrix (ECM) proteins. Twenty-nine adenocarcinomas, 5 adenomas and non-neoplastic mucosa samples were therefore investigated to determine their fibronectin (FN) and tenascin-C (TN-C) expression using in situ hybridization (ISH) and immunohistochemical staining. In the non-neoplastic mucosa, no mRNA signals were found. Two of the adenomas demonstrated positive signals in peri-cryptal cells and the vessels. In the cancers, TN-C and FN mRNAs were found in 86% and 96% of the total cases, respectively. The signals were mainly detected in myofibroblasts, labeled with alpha-smooth muscle actin, in the cancer stroma. TN-C mRNA-positive cells were often observed in localized areas, such as in cancer stroma associated with invading edges and/or in host tissues surrounding the invading cancer front, but rarely in the center of the tumors. FN mRNA-positive cells were more widely spread throughout the cancer stroma, although they were also frequently observed at invading edges. Vascular cells in cancer tissues were also labeled. In 10 specimens, cancer cells themselves expressed FN and/or TN-C mRNA. Comparison with histo-pathological findings revealed positive relationships between the degree of mRNA expression of FN and TN-C and the depth of invasion as well as the frequency of metastasis to lymph nodes. The expression of FN and TN-C by myofibroblasts, vascular cells and cancer cells could be important for the remodeling process of neoplastic tissues during cancer development and progression.

Morphologic pattern of tenascin as a diagnostic biomarker in colon cancer

BACKGROUND

Immunohistochemical methods were used to study the pattern of expression of tenascin (TN) in invasive colon cancer and its relation to prognosis.

METHODS

Sixty patients (29 males, 31 females) with a mean age of 77 years were studied. TN expression was evaluated by immunohistochemistry using paraffin-embedded tissue sections, TN expression levels were correlated with patient age, tumor stage, and survival.

RESULTS

TN positivity varied from trace to 4+. Staining patterns were as follows: in well-differentiated cancer, TN fibers form thick bands around invading tumor glands. In poorly differentiated cancer, TN fibers had an interstitial pattern surrounding individual tumor cells. Using Cox's proportional hazard regression method, survival was significantly related to TN score (P < 0.0001) and stage of disease (P < 0.05). No significant relationship was found between survival and age (P = 0.375).

CONCLUSION

Patients with more TN expression had better long-term survival than patients with no or weak TN expression. Pathologic and clinical entities in colon cancer have distinct immunohistochemical TN matrix patterns that may correlate with predictive value and long-term survival.

Stromal tenascin distribution as a prognostic marker in colorectal cancer

A total of 169 colorectal adenocarcinomas, obtained from patients with a median follow-up of 6.5 years, were studied with immunohistochemical staining on cryosections using a monoclonal anti-tenascin antibody to evaluate the possible association between the staining patterns and tumour stage, tumour differentiation and survival. We found two different staining patterns in the tumour stroma--a diffuse stromal fibrillar staining in 92 out of 169 (54%) tumours and a subglandular staining in the remaining 77 tumours. When the entire group of patients (P < 0.01) and the group of potentially cured patients (P < 0.03) were analysed univariately, it was found that diffuse stromal fibrillar staining was associated with a shorter survival time than subglandular staining. In a multivariate analysis, the Dukes' stage and age were independent prognostic factors, whereas the tenascin expression did not retain a clear independent relationship to survival (P = 0.06). Hence, it appears that the tumour expression of tenascin may be a potential prognostic marker in colorectal cancer, in so far as a diffuse stromal fibrillar staining pattern seems to indicate an increased risk of poor outcome. However, after adjustment for age and Dukes' stage, the additional prognostic value of tenascin remains to be established in further analyses.

Differential expression of extracellular matrix components during the morphogenesis of human gastric mucosa

BACKGROUND

Components of extracellular matrix play a crucial role in morphogenesis and epithelial cell differentiation. In this study, we examined the spatiotemporal expression and distribution of several major extracellular macromolecules of developing and adult human gastric mucosa, with particular emphasis on the pit-gland axis.

METHODS

Indirect immunofluorescence was performed on cryosections of developing and adult gastric tissues by using specific antibodies.

RESULTS

From 8 weeks of gestation onward, including adults, heparan sulfate proteoglycan, type IV collagen, and laminin alpha 1, beta 1, and gamma 1 chains were systematically and uniformly located at the basement membrane of the stratified epithelium (8-11 weeks) and of surface and pit-gland epithelia. Between 8 and 20 weeks of gestation, fibronectin and tenascin were colocalized throughout the entire mesenchyme. In adult mucosa, fibronectin was distributed at all levels of surface and glandular epithelium, whereas tenascin expression was restricted to surface and pit epithelial cells. The expression of the alpha 2 laminin chain was first detected at 12 weeks at the base of forming gastric glands. In the adult, the alpha 2 as opposed to the alpha 1 chain of laminin was confined to the basement membrane of the glandular and lower part of gastric pit epithelia.

CONCLUSIONS

This analysis of the composition of the extracellular matrix in human gastric mucosa suggests an important role for some of its components in morphogenesis and maintenance of gastric glands.

Role of stromal myofibroblasts infiltrating colon cancer in tumor invasion

In the normal colon, myofibroblasts are closely apposed to colonocytes where they deposit type IV collagen, the main basement membrane component. In colon carcinomas, this epithelial-mesenchymal association is physically disrupted, leading to the production of an abnormal, type IV collagen defective, basement membrane. Tumor-infiltrating myofibroblasts are migratory cells that accumulate at the invasive front of the colorectal carcinomas. They produce lytic enzymes able to degrade the basement membrane surrounding tumor glands. They also participate in the synthesis of the extracellular matrix components of the tumor stroma, which could subsequently alter the adhesive and migratory properties of the epithelial colon cancer cells. These results suggest that tumor-infiltrating myofibroblasts play a role in the invasion and metastasis of colorectal tumor cells.

Laminins, tenascin and type VII collagen in colorectal mucosa

The distribution of different laminin polypeptides, type VII collagen and tenascin has been studied in adult and foetal colorectal mucosa by using the indirect immunofluorescence technique. Immunoreactivity for laminin alpha 1 chain was located to basement membranes of epithelia, muscularis mucosae, and blood vessels, respectively in different segments of adult colon and rectum. Laminin beta 1 and gamma 1 chains were additionally expressed in lamina propria. Laminin alpha 2 chain was also found in lamina propria around the pericryptal fibroblasts. Immunoreactivity for laminin beta 2 chain was restricted to basement membranes in the muscularis mucosae and arteries. Laminin alpha 3 and beta 3 chains, suggestive for laminin-5, were confined especially to surface epithelial basement membranes. Immunoreactivity for type VII collagen was confined to basement membrane of surface epithelium in a punctate manner, while that for tenascin was seen slightly more broadly in the basement membrane zone and also in the muscular layer. The distribution of laminin chains in 16-week-foetal colon mostly resembled that of corresponding adult tissue, although immunoreactivities for laminin alpha 2 and beta 2 chains were lacking. Type VII collagen and the high molecular weight isoform of tenascin were also absent from the foetal colon. The results show that the basement membrane of the surface epithelium of colon and rectum express the components of epithelial adhesion complex, laminin-5 (alpha 3-beta 3-gamma 2) and type VII collagen, resembling in this respect small intestine and stomach while laminin-2 (alpha 2-beta 1-gamma 1) appears to be associated with pericryptal fibroblasts, and laminin-1 (alpha 1-beta 1-gamma 1) widely in most basement membranes.

Expression of tenascin in gastric carcinoma

Tenascin expression was determined by an immunohistochemical technique in 120 surgical specimens of gastric carcinoma to investigate its relationship with clinicopathological factors. Tenascin expression was more prominent in the neoplastic area than in the adjacent non-neoplastic mucosa. Tenascin was frequently observed in gastric mucosa with diffuse chronic gastritis, glandular atrophy and intestinal metaplasia. In the neoplastic area, tenascin expression was positive in 72 cases (60 per cent). Tumours with a high frequency of tenascin expression included: Borrmann type II (19 of 20), well or moderately differentiated tumours (52 of 63), tumours with expansive growth and with an intermediate growth pattern (40 of 42), and those with a medullary or intermediate-type stroma (55 of 73). There was no significant relationship between tenascin expression and age, sex, depth of tumour invasion, lymph node metastasis, invasion to lymphatic vessel, venous invasion and the 4-year survival rate.

Immunohistochemical expression of tenascin in normal stomach tissue, gastric carcinomas and gastric carcinoma in lymph nodes

The immunohistochemical expression of tenascin was examined in the normal adult mucosa of the stomach, primary tumours and lymph node metastases of gastric cancer patients. In normal gastric tissue tenascin was expressed in the muscularis mucosae, muscularis propria and vessel walls, however it was not expressed in either the mucosal connective tissue or the stromal tissue in the submucosal layer. In gastric cancer, tenascin was expressed in 35 of 85 primary tumours, and in 8 of 25 metastases in lymph nodes. Tenascin was located in the fibrous stroma surrounding foci of cancer. The expression of tenascin in the primary tumour did not correlate with the depth of invasion, lymph node metastasis or prognosis. Tenascin appears during the process of either malignant transformation or tumour progression in gastric cancer, and the positive expression of tenascin may be useful as a stromal marker for the early detection of gastric cancer.

Significance of tenascin serum level as tumor marker in primary colorectal carcinoma

Tenascin serum levels were evaluated in 118 patients with primary colorectal carcinoma and in a control group of 51 healthy persons in a double-sided sandwich ELISA. The data were correlated with post-operative TNM-staging. Patients with colorectal carcinomas had significantly higher serum levels of tenascin than the control group. At the 95% level of specificity, sensitivity was 25%. Tumor grading obviously had no influence on the level of tenascin in serum. With increasing pT-category, tenascin levels increased as well. In patients with distant metastatic disease, serum tenascin levels were significantly higher than in patients without distant metastases. These data suggest that, in colorectal carcinoma, the preoperative level of serum tenasin reflects the total tumor burden and correlates with metastatic disease. Our observation warrants a prospective study of the relevance of tenascin serum levels with regard to prognosis and as an indicator of relapse.