Alessandro Sgambato

Multiple functions of p27Kip1 and its alterations in tumor cells: a review

Cyclin‐dependent kinases (CDKs), together with cyclins, their regulatory subunits, govern cell‐cycle progression in eukaryotic cells. p27Kip1 is a member of a family of CDK inhibitors (CDIs) that bind to cyclin/CDK complexes and arrest cell division. There is considerable evidence that p27Kip1 plays an important role in multiple fundamental cellular processes, including cell proliferation, cell differentiation, and apoptosis. Moreover, p27Kip1 is a putative tumor‐suppressor gene that appears to play a critical role in the pathogenesis of several human malignancies and its reduced expression has been shown to correlate with poor prognosis in cancer patients. This study reviews current information on the functions of p27Kip1, its abnormalities found in human tumors, and the possible clinical implications of these findings with respect to the management of cancer patients. J. Cell. Physiol. 183:18–27, 2000.

Low Doses of Pristine and Oxidized Single-Wall Carbon Nanotubes Affect Mammalian Embryonic Development

Several in vitro and in vivo studies suggest local and systemic effects following exposure to carbon nanotubes. No data are available, however, on their possible embryotoxicity in mammals. In this study, we tested the effect of pristine and oxidized single-wall carbon nanotubes (SWCNTs) on the development of the mouse embryo. To this end, SWCNTs (from 10 ng to 30 μg/mouse) were administered to female mice soon after implantation (postcoital day 5.5); 10 days later, animals were sacrificed, and uteri, placentas, and fetuses examined. A high percentage of early miscarriages and fetal malformations was observed in females exposed to oxidized SWCNTs, while lower percentages were found in animals exposed to the pristine material. The lowest effective dose was 100 ng/mouse. Extensive vascular lesions and increased production of reactive oxygen species (ROS) were detected in placentas of malformed but not of normally developed fetuses. Increased ROS levels were likewise detected in malformed fetuses. No increased ROS production or evident morphological alterations were observed in maternal tissues. No fetal and placental abnormalities were ever observed in control animals. In parallel, SWCNT embryotoxicity was evaluated using the embryonic stem cell test (EST), a validated in vitro assay developed for predicting embryotoxicity of soluble chemical compounds, but never applied in full to nanoparticles. The EST predicted the in vivo data, identifying oxidized SWCNTs as the more toxic compound.

TNF-α Blockade Down-Regulates the CD40/CD40L Pathway in the Mucosal Microcirculation: A Novel Anti-Inflammatory Mechanism of Infliximab in Crohn’s Disease

The CD40/CD40 ligand (CD40L) pathway is involved in Crohn’s disease (CD) pathogenesis. In the patients’ circulation, soluble CD40L (sCD40L) levels are elevated and surface CD40L is increased in platelets and T cells, whereas in the intestine CD40 is overexpressed in the microvasculature and CD40L in platelets and T cells. The therapeutic effects of infliximab in CD are attributed to its systemic anti-TNF-α action, but because TNF-α modulates both CD40 and CD40L, we investigated whether infliximab affects the CD40/CD40L pathway in the intestine. Eighteen CD patients were evaluated before and after infliximab therapy. Plasma sCD40L was measured by ELISA and platelet and peripheral blood T cell (PBT) CD40L expression by flow cytometry. Microvascular CD40 and VCAM-1 expression were assessed in mucosal biopsies by immunohistochemistry and by flow cytometry in human intestinal microvascular endothelial cells (HIMEC). Cell cultures were performed in the presence and absence of infliximab. Infliximab treatment significantly reduced plasma sCD40L levels and eliminated CD40 and VCAM-1 from mucosal microvessels. In vitro infliximab prevented TNF-α-induced CD40 and VCAM-1 expression by HIMEC, and reduced PBT, but not platelet, surface CD40L expression and sCD40L release. In addition, infliximab decreased T cell-induced VCAM-1 expression in HIMEC by down-regulating CD40L in T cells and promoting T cells apoptosis. These findings point to a novel mechanism of action of infliximab, i.e., the disruption of CD40/CD40L-dependent cognate interactions between intestinal microvessels and T cells. Thus, in addition to neutralizing TNF-α and inducing T cell death, the therapeutic effects of infliximab in CD appear to be also mediated by inhibition of vascular inflammation in the gut.

Gut Microbial Flora, Prebiotics, and Probiotics in IBD: Their Current Usage and Utility

Inflammatory bowel diseases are chronic diseases affecting the gastrointestinal tract, whose major forms are represented by Crohns disease (CD) and ulcerative colitis (UC). Their etiology is still unclear, although several factors have been identified as major determinants for induction or relapses. Among these, the role of the “forgotten organ”, gut microbiota, has become more appreciated in recent years. The delicate symbiotic relationship between the gut microbiota and the host appears to be lost in IBD. In this perspective, several studies have been conducted to assess the role of prebiotics and probiotics in gut microbiota modulation. This is a minireview aimed to address in an easy format (simple questions-simple answers) some common issues about the theme. An update on the role of selected constituents of gut microbiota in the pathogenesis of IBD is presented together with the analysis of the efficacy of gut microbiota modulation by prebiotics and probiotics administration in the management of IBD.

Homocysteine triggers mucosal microvascular activation in inflammatory bowel disease

OBJECTIVES:Increased homocysteine contributes to the pathophysiology of several chronic inflammatory diseases. Whether homocysteine could participate in mucosal inflammation in inflammatory bowel disease (IBD) has not been explored yet. Our aims were to study the levels of plasma and mucosal homocysteine in IBD patients and to assess whether homocysteine can trigger an inflammatory reaction on human intestinal microvascular endothelial cells (HIMECs).METHODS:Homocysteine was measured in the plasma, mucosal biopsy, and lamina propria mononuclear cell (LPMC) supernatants from normal and IBD subjects. HIMEC were cultured in presence of homocysteine, TNF-α, or folic acid, alone or in combination. Expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular cell adhesion molecule 1 was measured by flow cytometry and monocyte chemoattractant protein-1 (MCP-1) production by ELISA. Phosphorylation of p38 and p42/44 was assessed by immunoblot in HIMEC extracts. T-cell- and monocyte-HIMEC adhesion assays were used to evaluate the impact of homocysteine on leukocyte adhesion to intestinal endothelial cells.RESULTS:Patients with IBD displayed significantly higher homocysteine plasma and mucosal levels than control subjects. IBD-derived LPMC released higher homocysteine than control-derived LPMC. Treatment of HIMEC with homocysteine, and synergistically with the combination of TNF-α and homocysteine, triggered HIMEC inflammation, resulting in VCAM-1 up-regulation, MCP-1 production, and p38 phosphorylation. These events lead to an increased capacity of HIMEC to adhere T- and monocyte cells and were blocked by folic acid treatment.CONCLUSIONS:Homocysteine is increased in both the mucosa and plasma of patients with Crohns disease and ulcerative colitis and contributes to the inflammatory state of the mucosal IBD endothelium. Therefore, homocysteine could play a proinflammatory role in IBD, which can be efficiently targeted by folic acid supplementation.

Dystroglycan Expression Is Frequently Reduced in Human Breast and Colon Cancers and Is Associated with Tumor Progression

Dystroglycan (DG) is an adhesion molecule responsible for crucial interactions between extracellular matrix and cytoplasmic compartment. It is formed by two subunits, alpha-DG (extracellular) and beta-DG (transmembrane), that bind to laminin in the matrix and dystrophin in the cytoskeleton, respectively. In this study we evaluated by Western blot analysis the expression of DG in a series of human cancer cell lines of various histogenetic origin and in a series of human primary colon and breast cancers. Decreased expression of DG was observed in most of the cell lines and in both types of tumors and correlated with higher tumor grade and stage. Analysis of the mRNA levels suggested that expression of DG protein is likely regulated at a posttranscriptional level. Evaluation of alpha-DG expression by immunostaining in a series of archival cases of primary breast carcinomas confirmed that alpha-DG expression is lost in a significant fraction of tumors (66%). Loss of DG staining correlated with higher tumor stage (P = 0.022), positivity for p53 (P = 0.033), and high proliferation index (P = 0.045). A significant correlation was also observed between loss of alpha-DG and overall survival (P = 0.013 by log-rank test) in an univariate analysis. These data indicate that DG expression is frequently lost in human malignancies and suggest that this glycoprotein might play an important role in human tumor development and progression.

Anomalous dystroglycan in carcinoma cell lines

Dystroglycan is a receptor responsible for crucial interactions between extracellular matrix and cytoplasmic space. We provide the first evidence that dystroglycan is truncated. In HC11 normal murine and the 184B5 non‐tumorigenic mammary human cell lines, the expected β‐dystroglycan 43 kDa band was found but human breast T47D, BT549, MCF7, colon HT29, HCT116, SW620, prostate DU145 and cervical HeLa cancer cells expressed an anomalous ≈31 kDa β‐dystroglycan band. α‐Dystroglycan was udetectable in most of the cell lines in which β‐dystroglycan was found as a ≈31 kDa species. An anomalous ≈31 kDa β‐dystroglycan band was also observed in N‐methyl‐N‐nitrosurea‐induced primary rat mammary tumours. Reverse transcriptase polymerase chain reaction experiments confirmed the absence of alternative splicing events and/or expression of eventual dystroglycan isoforms. Using protein extraction procedures at low‐ and high‐ionic strength, we demonstrated that both the 43 kDa and ≈31 kDa β‐dystroglycan bands harbour their transmembrane segment.

Cyclin D1 expression in papillary superficial bladder cancer: its association with other cell cycle-associated proteins, cell proliferation and clinical outcome.

Cyclin D1 contributes to regulate G1 progression by forming a complex with different cyclin‐dependent kinases. It has oncogenic properties and is frequently overexpressed in several human tumor types. In our study, expression of cyclin D1 and Ki67, a proliferation marker, was evaluated by immunohistochemistry in human papillary superficial (pTa‐pT1) bladder cancers and was correlated with p27Kip1, p21Waf1 and c‐erbB‐2 expression, with p53 gene status and protein expression, ploidy and cancer progression. Cyclin D1 expression was neither associated with tumor stage nor with tumor grade but high cyclin D1 expression (≥25% positive nuclei) was significantly associated with p53 gene mutation (p = 0.012), low p21Waf1 (p = 0.015) and high p27Kip1 (p = 0.016) protein expression. Ki67 expression was not associated with tumor stage but a high proliferation index (≥10% positive nuclei) was significantly associated with high tumor grade (p = 0.001) and with DNA aneuploidy (p = 0.005). There was no significant difference in proliferative activity between high and low cyclin D1 expressor tumors. Patients whose tumors showed high expression of cyclin D1 displayed a significantly longer disease‐free survival (p < 0.001 by log‐rank test). Increased Ki67 expression was significantly associated with shorter disease‐free survival (p = 0.003). Both cyclin D1 (p = 0.027; RR = 1.898) and Ki67 (p = 0.047; RR = 1.932) protein expressions were independent predictors of reduced disease‐free survival on a multivariate analysis that also included p27Kip1 expression and tumor stage. The simultaneous presence of low cyclin D1, low p27Kip1 and high Ki67 expression defined a “high‐risk” group of patients who displayed a significantly increased risk of recurrence (p < 0.0001). These results suggest that evaluation of cell cycle‐associated markers can help to identify high‐risk patients and may affect the management of patients with papillary superficial bladder cancer.

Reduced expression and altered subcellular localization of the cyclin-dependent kinase inhibitor p27Kip1 in human colon cancer

The p27Kip1 protein is a negative regulator of the cell cycle and a potential tumor suppressor gene. Reduced expression of the p27Kip1 protein has been reported in several human tumors and has been associated with higher tumor grade and increased mortality in breast, lung, colon, prostate, bladder, and gastric cancers. On the other hand, increased expression of the p27Kip1 protein, in the absence of gene mutation, has been observed in primary colon and breast cancers. It was recently suggested that sequestration in the cytoplasm might be an alternative way to inactivate p27Kip1‐associated inhibitory activity. This study was undertaken to further evaluate p27Kip1 expression in primary colon tumors and to verify whether differences exist between normal and cancer tissues in terms of subcellular localization of this protein. Both normal and neoplastic tissues expressed variable amounts of the p27Kip1 protein, as assessed by western blot analyses. Although the mean values were not different between tumor and normal mucosa samples, the expression of total p27Kip1 was reduced in a subset of tumors. Decreased levels of total p27Kip1 were associated with high tumor grade (P=0.03) and stage (P=0.04). Moreover, while there was no significant difference in nuclear p27Kip1, the amount of p27Kip1 in the cytoplasmic fraction was significantly higher in the tumor samples than in the normal mucosa samples (P=0.0001). These results suggest that p27Kip1 expression is lost in a subset of colorectal tumors and that alterations in the subcellular localization of this protein might play a role in colon carcinogenesis. Mol. Carcinog. 26:172–179, 1999.

The dystroglycan complex: From biology to cancer

Dystroglycan (DG), a non‐integrin adhesion molecule, is a pivotal component of the dystrophin–glycoprotein complex, that is expressed in skeletal muscle and in a wide variety of tissues at the interface between the basement membrane (BM) and the cell membrane. DG has been mainly studied for its role in skeletal muscle cell stability and its alterations in muscular diseases, such as dystrophies. However, accumulating evidence have implicated DG in a variety of other biological functions, such as maturation of post‐synaptic elements in the central and peripheral nervous system, early morphogenesis, and infective pathogens targeting. Moreover, DG has been reported to play a role in regulating cytoskeletal organization, cell polarization, and cell growth in epithelial cells. Recent studies also indicate that abnormalities in the expression of DG frequently occur in human cancers and may play a role in both the process of tumor progression and in the maintenance of the malignant phenotype. This paper reviews the available information on the biology of DG, the abnormalities found in human cancers, and the implications of these findings with respect to our understanding of cancer pathogenesis and to the development of novel strategies for a better management of cancer patients.