Vimentin regulates lung cancer cell adhesion through a VAV2-Rac1 pathway to control focal adhesion kinase activity

Vimentin is an intermediate filament protein whose expression correlates with increased metastatic disease, reduced patient survival, and poor prognosis across multiple tumor types. Despite these well-characterized correlations, the molecular role of vimentin in cancer cell motility remains undefined. To approach this, we used an unbiased phosphoproteomics screen in lung cancer cell lines to discover cell motility proteins that show significant changes in phosphorylation upon vimentin depletion. We identified the guanine nucleotide exchange factor (GEF) VAV2 as having the greatest loss of phosphorylation due to vimentin depletion. Since VAV2 serves as a GEF for the small Rho GTPase Rac1, a key player in cell motility and adhesion, we explored the vimentin-VAV2 pathway as a potential novel regulator of lung cancer cell motility. We show that VAV2 localizes to vimentin positive focal adhesions (FAs) in lung cancer cells and complexes with vimentin and focal adhesion kinase (FAK). Vimentin loss impairs both pY142-VAV2 and downstream pY397-FAK activity showing that vimentin is critical for maintaining VAV2 and FAK activity. Importantly, vimentin depletion reduces the activity of the VAV2 target, Rac1, and a constitutively active Rac1 rescues defects in FAK and cell adhesion when vimentin or VAV2 is compromised. Based upon this data, we propose a model whereby vimentin promotes FAK stabilization through VAV2-mediated Rac1 activation. This model may explain why vimentin expressing metastatic lung cancer cells are more motile and invasive.

HOMA-IR and non-HDL-C as predictors of high cholesteryl ester transfer protein activity in patients at risk for type 2 diabetes

BACKGROUND AND AIMS

Metabolic syndrome (MS) and type 2 diabetes are highly associated with an abnormal lipoprotein profile, which may be generated and accentuated by high cholesteryl ester transfer protein (CETP) activity. Given the difficulty in measuring CETP activity, the aim was to identify simple biochemical predictors of high CETP activity.

DESIGN AND METHODS

Eighty five subjects at risk for type 2 diabetes were classified according to the presence of MS. Lipoprotein profile, HOMA-IR and endogenous CETP activity were evaluated.

RESULTS

As expected, MS patients presented higher concentration of glucose, insulin, triglycerides and non-HDL-C and lower HDL-C levels. Moreover, MS patients exhibited increased HOMA-IR and CETP activity. Employing a ROC curve for MS, high CETP activity was defined as >250%ml⁻¹ h⁻¹. The predictive variables of high CETP were non-HDL-C≥160mg/dl (OR=11.1;95%IC=3.3-38.2;p<0.001) and HOMA-IR>2.1 (OR=4.4;95%IC=1.3-14.8;p<0.05).

CONCLUSIONS

High non-HDL-C and insulin resistance were predictors for increased CETP activity which measurement is not accessible for clinical laboratories.

A secreted BMP antagonist, Cer1, fine tunes the spatial organization of the ureteric bud tree during mouse kidney development

The epithelial ureteric bud is critical for mammalian kidney development as it generates the ureter and the collecting duct system that induces nephrogenesis in dicrete locations in the kidney mesenchyme during its emergence. We show that a secreted Bmp antagonist Cerberus homologue (Cer1) fine tunes the organization of the ureteric tree during organogenesis in the mouse embryo. Both enhanced ureteric expression of Cer1 and Cer1 knock out enlarge kidney size, and these changes are associated with an altered three-dimensional structure of the ureteric tree as revealed by optical projection tomography. Enhanced Cer1 expression changes the ureteric bud branching programme so that more trifid and lateral branches rather than bifid ones develop, as seen in time-lapse organ culture. These changes may be the reasons for the modified spatial arrangement of the ureteric tree in the kidneys of Cer1+ embryos. Cer1 gain of function is associated with moderately elevated expression of Gdnf and Wnt11, which is also induced in the case of Cer1 deficiency, where Bmp4 expression is reduced, indicating the dependence of Bmp expression on Cer1. Cer1 binds at least Bmp2/4 and antagonizes Bmp signalling in cell culture. In line with this, supplementation of Bmp4 restored the ureteric bud tip number, which was reduced by Cer1+ to bring it closer to the normal, consistent with models suggesting that Bmp signalling inhibits ureteric bud development. Genetic reduction of Wnt11 inhibited the Cer1-stimulated kidney development, but Cer1 did not influence Wnt11 signalling in cell culture, although it did inhibit the Wnt3a-induced canonical Top Flash reporter to some extent. We conclude that Cer1 fine tunes the spatial organization of the ureteric tree by coordinating the activities of the growth-promoting ureteric bud signals Gndf and Wnt11 via Bmp-mediated antagonism and to some degree via the canonical Wnt signalling involved in branching.

[Central obesity: relationship between conicity index and lipoprotein risk factors for coronary atherosclerosis]

In middle age men the relationship between biochemical and anthropometric parameters was studied associated with central obesity in order to evaluate the risk of coronary atherosclerosis. In 31 males of 30 to 65 years of age, "apparently healthy", we determined the percentile 50 (P50) for body fat percentage (PG), 26.8% (utilizing the skinfold thicknesses) and P75 of Conicity Index (IC), 1.26. Were selected 63 subjects with different values of PG and IC. IC, adjusted for BMI and PG, correlated with Cholesterol (CT), Triglycerides (TG), CT/C-HDL, C-LDL/C-HDL, Apolipoprotein B (ApoB), Apo B/C-HDL, (P < 0.01) in all cases), and cholesterol LDL (C-LDL) (P < 0.05). This population was divided in three groups: Group I, Control, N = 19, PG < = 27% and IC < 1.26; Group II, obese without Central Obesity Predominance (POC), N = 15, PG < or = 27% and IC < or = 1.26; Group III, N = 23, obese with POC, PG > 27% and IC < or = 1.26. We found that Group III vs Group II had: CT 242 +/- 35 vs 205 +/- 40 mg/dl (P < 0.01), C-LDL 165 +/- 41 vs 138 +/- 36 mg/dl (P < 0.05) and CT/C-HDL 6.0 +/- 1.2 VS 5.1 +/- 1.2 (p < 0.05) respectively. Group III vs I showed significant differences for all biochemical parameters and index studied with exception of C-HDL. In subjects with IC > 1.26 vs IC < = 1.26 increased the frequency of coronary risk factors and indicators: CT > or = 240 mg/dl, 59% vs 12% (P < 0.001); C-LDL > or = 160 mg/dl, 55% vs 18% (P < 0.001); Apo B > 120 mg/dl, 72% vs 26% (P < 0.001); CT/C-HDL > 4.5, 86% vs 53% (P < 0.01); C-LDL/C-HDL > 3.0, 86% vs 47% (P < 0.001); Apo B/C-HDL > 2.6, 72% vs 47% (P < 0.05). Our results suggest that the use of IC combined with lipoproteic factors and index will contribute to the detection of males at risk of coronary heart disease.