TGF-beta in CAF-mediated tumor growth and metastasis.

TGF-beta signaling is one of the major pathways controlling cell and tissue behavior not only in homeostasis but also in disease. During tumorigenesis TGF-beta orchestrated processes are key due to its dual role as tumor suppressor and tumor promoter. Important functions of this pathway have been described in a context-dependent manner both in epithelial cancer cells and in the tumor microenvironment during tumor progression. Carcinoma-associated fibroblasts (CAFs) are one of the most abundant stromal cell types in virtually all solid tumors. CAFs favor malignant progression by providing cancer cells with proliferative, migratory, survival and invasive capacities. A complex network of signaling pathways underlying their tumor-promoting properties is beginning to take shape. In this review, we examine current evidence on the emerging mechanisms involving TGF-beta in CAF-mediated cancer progression, and discuss their potential as therapeutic targets.

Different effects of the Cdx1 and Cdx2 homeobox genes in a murine model of intestinal inflammation.

AIMS: The CDX1 and CDX2 homeoproteins are intestine-specific transcription factors regulating homeostasis. We investigated their relevance in experimentally-induced intestinal inflammation. METHODS: The response to intestinal inflammation induced by dextran sodium sulfate (DSS) was compared in wild type, Cdx1(-/-) and Cdx2(+/-) mice. Intestinal permeability was determined in wild type and Cdx2(+/-) mice. Protein-protein interactions were investigated by co-immunoprecipitation and GST-pulldown, and their functional consequences were assessed using Luciferase reporter systems. RESULTS: Heterozygous Cdx2(+/-) mice, but not Cdx1(-/-) mice, were hypersensitive to DSS-induced acute inflammation as all these mice showed blood in the stools at day 1 of DSS treatment. Hypersensitivity was associated to a 50% higher intestinal permeability. In Cdx2(+/-) mice, the colonic epithelium was repaired during the week after the end of DSS treatment, whereas two weeks were required for wild type animals. Subsequently, no colonic tumour was observed in Cdx2(+/-) mice subjected to 5 repeated cycles of DSS, in contrast to the 2.7 tumours found per wild type mouse. Based on the fact that Smad3(+/-) mice, like Cdx2(+/-) mice, better repair the damaged intestinal epithelium, we found that the CDX2 protein interacts with SMAD3, independently of SMAD4, resulting in a 5-fold stimulation of SMAD3 transcriptional activity. CDX1 also interacted with SMAD3 but it inhibited by 10-fold the SMAD3/SMAD4-dependent transcription. CONCLUSION: The Cdx1 and Cdx2 homeobox genes have distinct effects on the outcome of a pro-inflammatory challenge. This is mirrored by different functional interactions of the CDX1 and CDX2 proteins with SMAD3, a major element of the TGFbeta signalling pathway.

Ventricular septal motion and left ventriclular dimensions during abnormal ventricular activation.

To determine the effect of abnormal ventricular activation on ventricular septal motion, left ventricular endocardial motion and left ventricular dimensions, 12 patients with normal motion were studied with echocardiography during incremental pacing of the right ventricular apex, outflow and inflow regions. Three types of abnormal ventricular septal motion were seen: The type I pattern was characterized by an early rapid preejection posterior ventricular septal motion followed by another posterior systolic motion that lasted throughout ejection, both of which were associated with septal thickening. In the type II pattern an early rapid preejection posterior ventricular septal motion was followed by an anterior ejection motion; the latter was not accompanied by septal thickening. The type III pattern consisted of an early preejection posterior ventricular septal motion followed by a mid and late systolic posterior motion: the latter motion extended through diastole. During right ventricular apical pacing, 8 of 11 patients showed a type 1 pattern, 1 a type II pattern and 2 a normal septal motion. During right ventricular outflow pacing,seven of nine patients showed a type II pattern, one a type III pattern and one a type I pattern. During right ventricular inflow pacing, eight of nine patients showed a type II pattern and one a type III pattern. At faster pacing rates patterns of types I and III changed to a type II pattern (five patients). End-diastolic dimensions decreased significantly during incremental right ventricular pacing when compared with those during sinus rhythm. End-systolic dimensions decreased significantly only during right ventricular apical and outflow pacing at maximal rates. In the seven patients who had pacing from all three sites, the decrease in left ventricular dimensions did not significantly differ when the three pacing sites were compared. These findings suggest that (1) abnormal ventricular septal motion during right ventricular pacing (induced left bundle branch block patterns) is dependent on the sequence of ventricular activation; (2) ventricular septal motion during right ventricular outflow and inflow pacing is similar to that seen in spontaneous left bundle branch block, whereas the pattern of septal motion during right ventricular apical pacing is different from that of spontaneous left bundle branch block; and (3) changes in left ventricular dimension are dependent on ventricular pacing rate but independent of pacing site.

The intestine-specific homeobox gene Cdx2 decreases mobility and antagonizes dissemination of colon cancer cells.

The gravity of colorectal cancer is mainly due to the capacity of tumor cells to migrate out of the tumor mass to invade the stroma and disseminate as metastases. The acquisition of a migratory phenotype also occurs during wound healing. Here, we show that several features characterizing invasive colon tumor cells are shared by migrating cells during wound repair in vitro. In particular, the expression of the intestine-specific transcription factor Cdx2, a key gene for intestinal identity downregulated in invasive cancer cells, is reduced during wound healing in vitro. Transcription factors involved in epithelial-mesenchymal transition such as Snail and Slug are upregulated during wound healing and are able to repress Cdx2 transcription. In vitro, forced expression of Cdx2 in human colon cancer cell lines retarded wound repair and reduced migration, whereas inhibition of Cdx2 expression by RNA interference enhanced migration. In vivo, forced expression of Cdx2 opposed tumor cells spreading in nude mice xenografted at three different sites. These data provide evidence that Cdx2 antagonizes the process of tumor cell dissemination, and they suggest that this homeobox gene might represent a new therapeutic target against metastatic spreading of colon cancer.

Cdx1, a dispensable homeobox gene for gut development with limited effect in intestinal cancer.

The homeobox gene Cdx1 is involved in anteroposterior patterning in embryos and its expression selectively persists in the intestinal epithelium throughout life. In human colon cancers, Cdx1 is overexpressed in few cases and lost in the majority of adenocarcinomas. We used mouse models of gain and loss-of-function to investigate the role of Cdx1 in intestinal development and cancers. Transgenic mice overexpressing Cdx1 and knockout mice exhibited a morphologically normal intestine. Cell proliferation, specification into the four differentiated lineages and migration along the crypt-villus axis were unchanged compared to wild-type mice. Changing Cdx1 caused an inverse and dose-dependent modification of the expression of the paralogous gene Cdx2, indicating that Cdx1 fine-tunes Cdx2 activity. Transgenenic and knockout mice failed to spontaneously develop tumours. Overexpressing Cdx1 was without incidence on the frequency of intestinal tumours induced chemically by azoxymethane treatment or genetically in Apc(Delta14/+) mice. However, it augmented the severity of the tumours in Apc(Delta14/+) mice. Inversely, the loss-of-function of Cdx1 in knockout mice was without incidence on the growth of tumours induced by azoxymethane. We conclude that Cdx1 is dispensable for intestinal development and that its overexpression could increase malignancy in early stages of tumourigenesis.

Induction of iatrogenic electrocardiographic patterns during electrophysiologic studies.

Indwelling cardiac catheters by producing local mechanical stimulation or trauma can induce electrocardiographic (ECG) patterns which simulate known electrophysiologic phenomena. Catheter-induced ECG patterns were analyzed in 447 consecutive patients undergoing electrophysiologic studies. Iatrogenic nature of these patterns was suggested by 1) absence prior to placement of catheter; 2) sudden appearance with catheter placement and disappearance with catheter repositioning; 3) reoccurrence with remanipulation of catheters; and 4) simulation (in some cases) by programmed electrical stimulation from the catheter. Common catheter-induced patterns were 1) right bundle branch block (RBBB) lasting less than 24 hours occurred in 19 patients; 2) transient third degree atrioventricular block in His-Purkinje system developed in 3/13 patients with pre-existing left BBB; 3) catheter-induced ventricular pre-excitation which simulated ECG patterns of type B Wolff-Parkinson-White syndrome; 4) fortuitous synchronization of right ventricular excitation from the catheter, and left ventricular excitation from sinus beat resulted in normalization of the QRS complexes in 5/68 patients with pre-existing RBBB; 5) premature beats from the atria, right ventricle, and His bundle, which were common, resulted in complex ECG patterns. These iatrogenic ECG patterns must be identified in order to avoid errors in interpretation.