Expression of membrane type 1 matrix metalloproteinase (MT1-MMP) in A2058 melanoma cells is associated with MMP-2 activation and increased tumor growth and vascularization

Membrane-type metalloproteinase-1 (MT1-MMP) is a transmembrane metalloproteinase overexpressed in tumors, which plays a major role in the first step of pro-MMP-2 activation, leading to the generation of an intermediate 62 kDa species. The second step of MMP-2 activation that yields to the mature form is less understood and could involve an autocatalytic process and/or the activity of the plasminogen/plasmin system. Human melanoma A2058 cells, which express MMP-2 only in its pro-form, were used to determine the role of MT1-MMP during pericellular proteolysis and tumor progression. The induction of MT1-MMP overexpression by MT1-MMP cDNA transfection initiated the first step of MMP-2 activation. We provide evidence that a cooperation between the plasminogen/plasmin system and MT1-MMP endowed the cells with the ability to fully activate MMP-2 and with enhanced invasive properties in vitro. When injected subcutaneously in nude mice, MT1-MMP expressing clones induced rapid tumor growth and high tumor vascularization, while the control clones were poorly or not tumorigenic. Our data provide the first demonstration, in an experimental model, that MT1-MMP expression by tumor cells promotes tumor vascularization.     

Pharmacokinetic and tumor-seeking properties of recombinant and nonrecombinant anti-carcinoembryonic antigen antibody fragments

Production of recombinant antibody fragments in bacterial expression systems results in intentional or fortuitous differences compared to the original products prepared by hybridoma technology. These differences may have significant effects not only on antigen-binding properties but also on pharmacokinetic and tumor-seeking properties. Our major goal was to investigate some of these possible differences. We produced in Escherichia coli an rFab' fragment containing only 1 cysteine residue in the hinge region; the fragment was derived from a mouse MAb (F6) specific for CEA. The rFab' had a slightly lower m.w. and a higher isoelectric point relative to the corresponding nonrecombinant fragment (pFab'). This was explained by the absence of N-glycosylation on the V kappa domain of rFab'. V kappa glycosylation had no significant effect on antibody-binding affinity and kinetics. However, rFab' was eliminated from the circulation much faster than pFab', and the maximal dose accumulated in the tumor was reduced relative to pFab'. Thus, glycosylation appears to modify the targeting efficiency of antibody fragments. rF(ab')(2) fragments were obtained either spontaneously from the culture supernatant of E. coli or by chemical cross-linking [rcF(ab')(2)]. We observed improved tumor targeting with rcF(ab')(2) compared to rF(ab')(2), which could be explained by the greater stability of the thioether compared to the disulfide linkage. These results demonstrate that a single cysteine residue in the hinge region of rFab' is particularly well suited to prepare stable, chemically coupled, bivalent or bispecific antibodies, avoiding intrahinge disulfide bonding and thus achieving higher production yields.     

Neuropathological analysis of an adult case of the Cornelia de Lange syndrome

Cornelia de Lange syndrome (CDLS) is a rare multisystemic malformative syndrome of uncertain etiology characterized by severe psychomotor and mental retardation. Here we report the neuropathological analysis of a 35-year-old patient who displayed the classical clinical symptomatology of CDLS. A congenital dysgenesis of the brain was evident including abnormal convolution patterns of the cerebral gyri, frontal lobe hypoplasia and focal lack of myelination in layers V and VI of the left temporal cortex. In addition, there were vascular scars in the CA2-3 region of the left hippocampus and in the right parietal cortex as well as a few neurofibrillary tangles in the CA fields of the hippocampus and in the entorhinal cortex. In contrast to previous reports, there were no midline cerebral dysgenesis and no ectopic neuron formations in the present case. Neuronal loss and gliosis were also absent in all cortical and subcortical areas. Our observations suggest that the main neurodevelopmental deficits in CDLS occur during the late phase of gestation. Conversely, early neurodegenerative changes are not characteristic of CDLS. In the light of previous studies in younger CDLS patients, the vascular and degenerative lesions observed in the present case may be secondary to his severe congenital heart abnormalities and self-injury behavior, respectively.     

Clinical presentations and laboratory investigations in respiratory chain deficiency

Respiratory chain deficiencies have long been regarded as neuromuscular diseases. In fact, oxidative phosphorylation, i.e., ATP synthesis by the respiratory chain not only occurs in the neuromuscular system, indeed, a number of nonneuromuscular organs and tissues are dependent upon mitochondrial energy supply. For this reason, a respiratory chain deficiency can theoretically give rise to any symptom, in any organ or tissue, at any age with any mode of inheritance, due to the twofold genetic origin of respiratory enzymes (nuclear DNA and mitochondrial DNA).     

Previous oral contraceptive use and breast cancer risk according to hormone replacement therapy use among postmenopausal women

Objective To assess postmenopausal breast cancer risk in relation to particular patterns of oral contraceptive (OC) use according to hormone replacement therapy (HRT) exposure.Methods Time-dependent Cox regression models were used to analyse information on postmenopausal women from a large-scale French cohort. Among a total of 68,670 women born between 1925 and 1950, 1405 primary invasive postmenopausal breast cancer cases were identified from 1992 to 2000.Results A non-significant decrease in risk of around 10% was associated with ever OC use as compared to never OC use in postmenopausal women. No significant interaction was found between OC and HRT use on postmenopausal breast cancer risk. Breast cancer risk decreased significantly with increasing time since first OC use (test for trend: p=0.01); this was consistent after adjustment for duration of use or for time since last use.Conclusion No increase in breast cancer risk was associated with previous OC exposure among postmenopausal women, probably because the induction window had closed. Some women may develop breast cancer soon after exposure to OCs, leading to a deficit of cases of older women. Further investigation is therefore required to identify young women at high risk.* Address correspondence to: F. Clavel-Chapelon, Equipe E3N-EPIC, INSERM “Nutrition, Hormones, Cancer”, Institut Gustave-Roussy, 94805 – Villejuif, France.     

Stratification of intermediate-risk endometrial cancer patients into groups at high risk or low risk for recurrence based on tumor gene expression profiles.

PURPOSE: Endometrial cancers classified as "intermediate risk" based on clinical and/or pathologic features are associated with a 15% to 20% risk of recurrence. Here, we test whether global gene expression profiling can distinguish intermediate-risk tumors into high-risk and low-risk subgroups. EXPERIMENTAL DESIGN: Tumor specimens were obtained from 75 intermediate-risk endometrial cancer patients, 13 who had recurred and 62 who had not recurred with a median follow-up of 24 months. Gene expression profiles were obtained using the Affymetrix U133A GeneChip oligonucleotide microarray. The genes most associated with risk of recurrence were used to create a risk score using a leave-one-out cross-validation method and the univariate Cox proportional hazards regression model. Time to recurrence curves for the high-risk and low-risk subgroups were estimated using the Kaplan-Meier method, and the difference in time to recurrence between these two subgroups was tested using the log-rank test. RESULTS: There was a significant difference in time to recurrence between high-risk and low-risk patients using risk scores as defined above (P = 0.04). The estimated hazard ratio (95% confidence interval) was 3.07 (1.00-9.43). CONCLUSIONS: Patients with intermediate-risk endometrial cancers identified as high-risk for recurrence according to a gene expression-based risk score have a significantly increased risk for recurrence compared with those classified as low risk. These findings suggest that gene expression profiling can potentially contribute to the clinical classification and management of intermediate-risk endometrial cancers.     

Peroxisome proliferator-activated receptor beta/delta exerts a strong protection from ischemic acute renal failure

Ischemic acute renal failure is characterized by damages to the proximal straight tubule in the outer medulla. Lesions include loss of polarity, shedding into the tubule lumen, and eventually necrotic or apoptotic death of epithelial cells. It was recently shown that peroxisome proliferator-activated receptor beta/delta (PPARbeta/delta) increases keratinocyte survival after an inflammatory reaction. Therefore, whether PPARbeta/delta could contribute also to the control of tubular epithelium death after renal ischemia/reperfusion was tested. It was found that PPARbeta/delta+/- and PPARbeta/delta-/- mutant mice exhibited much greater kidney dysfunction and injury than wild-type counterparts after a 30-min renal ischemia followed by a 36-h reperfusion. Conversely, wild-type mice that were given the specific PPARbeta/delta ligand L-165041 before renal ischemia were completely protected against renal dysfunction, as indicated by the lack of rise in serum creatinine and fractional excretion of Na+. This protective effect was accompanied by a significant reduction in medullary necrosis, apoptosis, and inflammation. On the basis of in vitro studies, PPARbeta/delta ligands seem to exert their role by activating the antiapoptotic Akt signaling pathway and, unexpectedly, by increasing the spreading of tubular epithelial cells, thus limiting potentially their shedding and anoikis. These results point to PPARbeta/delta as a remarkable new target for preconditioning strategies.     

Early event-related potential changes during working memory activation predict rapid decline in mild cognitive impairment

BACKGROUND: The conversion of mild cognitive impairment (MCI) to Alzheimer's disease is associated with substantial compromise of neocortical circuits subserving rapid cognitive functions such as working memory. Event-related potential (ERP) analysis is a powerful tool to identify early impairment of these circuits, yet research for an electrophysiological marker of cognitive deterioration in MCI is scarce. Using a "2-back" activation paradigm, we recently described an electrophysiological correlate of working memory activation (positive-negative working memory [PN(wm)] component) over parietal electrodes. METHODS: Ours was a longitudinal study of 24 MCI patients with ERP analysis at inclusion and neuropsychological follow-up after 1 year. We used ERP waveform subtraction analysis between the n-back and control tasks. Analysis of variance (ANOVA) was used to compare electroencephalograph latencies between progressive MCI (PMCI) and stable MCI (SMCI), and univariate regression was used to assess the relationship between neuropsychological measures at baseline and clinical outcome. RESULTS: Thirteen (54%) MCI patients showed PMCI, and 11 (46%) remained stable (SMCI). In SMCI, a PN(wm) component with significantly larger density compared to baseline was identified when subtracting the detection task for both the 1- and 2-back tasks. In contrast, in PMCI, the PN(wm) component was absent in both 1-back and 2-back conditions. Neuropsychological variables and n-back test performance at inclusion did not predict cognitive deterioration 1 year later. CONCLUSIONS: In conjunction with recent functional imaging data, the present results support the notion of an early dysfunction of neural generators within the parietal cortex in MCI. They also reveal that the absence of the PN(wm) component may provide an easily applicable qualitative predictive marker of rapid cognitive deterioration in MCI.