GRECOS Project (Genotyping Recurrence Risk of Stroke): The Use of Genetics to Predict the Vascular Recurrence After Stroke

BACKGROUND AND PURPOSE

Vascular recurrence occurs in 11% of patients during the first year after ischemic stroke (IS) or transient ischemic attack. Clinical scores do not predict the whole vascular recurrence risk; therefore, we aimed to find genetic variants associated with recurrence that might improve the clinical predictive models in IS.

METHODS

We analyzed 256 polymorphisms from 115 candidate genes in 3 patient cohorts comprising 4482 IS or transient ischemic attack patients. The discovery cohort was prospectively recruited and included 1494 patients, 6.2% of them developed a new IS during the first year of follow-up. Replication analysis was performed in 2988 patients using SNPlex or HumanOmni1-Quad technology. We generated a predictive model using Cox regression (GRECOS score [Genotyping Reurrence Risk of Stroke]) and generated risk groups using a classification tree method.

RESULTS

The analyses revealed that rs1800801 in the MGP gene (hazard ratio, 1.33; P=9×10^-03), a gene related to artery calcification, was associated with new IS during the first year of follow-up. This polymorphism was replicated in a Spanish cohort (n=1.305); however, it was not significantly associated in a North American cohort (n=1.683). The GRECOS score predicted new IS (P=3.2×10^-09) and could classify patients, from low risk of stroke recurrence (1.9%) to high risk (12.6%). Moreover, the addition of genetic risk factors to the GRECOS score improves the prediction compared with previous Stroke Prognosis Instrument-II score (P=0.03).

CONCLUSIONS

The use of genetics could be useful to estimate vascular recurrence risk after IS. Genetic variability in the MGP gene was associated with vascular recurrence in the Spanish population.

Transforming growth factor beta engages TACE/ADAM17 and ErbB3 to activate PI3K/Akt in HER2-overexpressing breast cancer and desensitizes cells to trastuzumab

Abstract #35

TGFb signaling synergizes with HER2 in breast cancer progression. Exogenous TGFb or expression of an activated TGFb type I receptor (Alk5T204D) in MCF10A/HER2 and BT474 cells activated PI3K/Akt and enhanced survival and migration. In both cell types, TGFb stimulated P-EGFR and P-HER2 as well as the association of p85, the regulatory subunit of PI3K, with Y1289 P-ErbB3 which, in turn, activated PI3K/Akt. RNA interference of ErbB3 or treatment with pertuzumab, an antibody that blocks HER2-mediated activation of ErbB3, blocked TGFb-induced P-ErbB3, P-Akt, and cell motility. Treatment with TGFb or expression of Alk5TD increased protein levels of secreted TGFalpha, amphiregulin, and heregulin without a change in mRNA levels. The increase on secreted ErbB ligands without a change in mRNA levels suggested increased shedding of ErbB pro-ligands by tumor necrosis factor a-converting enzyme (TACE). Transfection of siRNA against human TACE but not control siRNA abrogated TGFb-stimulated ErbB receptor phosphorylation, P-Akt, and cell invasiveness. Transfection of full-length mouse TACE but not truncated TACE lacking the cytoplasmic domain reconstituted TGFb-induced ErbB phosphorylation in cells transfected with human TACE siRNA. TGF-b increased TACE phosphorylation in both serine and threonine as measured by P-Ser and P-Thr immunoblots of TACE pull downs. Incubation of TACE with Alk5TD in the presence of ATP in vitro resulted in both Ser and Thr phosphorylation in full-length but not truncated TACE. Further, addition of TGFb or expression of Alk5TD desensitized SKBR3 and BT474 cells to trastuzumab. Treatment with the type I TGFb receptor (Alk5) small molecule inhibitor LY2109761, the PI3K inhibitor LY294002, or siRNA against ErbB3 or TACE restored the inhibitory effect of trastuzumab. Finally, we generated an active Alk5 expression signature by selecting genes that were differentially expressed between BT474/Alk5TD and BT474/vector cells. Mapping of this signature to a previously published 295-breast tumor array (van de Vijver et al. and Chang et al.) revealed 90 of 271 genes in the Alk5TD signature with a >1.5-fold change from the median expression which correlated with HER2-positive and basal-like tumors and conferred a worse recurrence-free (RFS) and overall survival (OS) (RFS p=0.05, OS p=0.01). Hierarchical clustering analysis to an array data set reported by Harris et al. in 22 patients with HER2+ breast cancer treated with neoadjuvant trastuzumab and vinorelbine (Clin. Cancer Res. 2007) showed that the Alk5TD signature correlated with tumors that did not respond clinically. These data suggest that TGFb potentiates signaling downstream ErbB receptors via TACE, ErbB3, and PI3K, thus contributing to tumor progression and resistance to anti-HER2 therapies.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 35.

Nutrition and learning in Chilean school age children: Chile's Metropolitan Region Survey 1986-1987

The objective of this study was to determine the interrelationship between the scholastic achievement (SA) test and nutritional status of a representative sample of 4,509 elementary and high school children from Chile's Metropolitan Region. Percentages of weight/age (W/A), height/age (H/A), and weight/height (W/H) were compared to WHO (World Health Organization) Tables, head circumference/age (HC/A) to the Tanner Tables, and brachial anthropometry to Frisancho's norms. Socioeconomic status (SES) was measured by means of Graffar's Modified Method; SA by means of a language and mathematics test. Statistical analysis included correlation, regression, and WHO risk-approach methodology. Results showed that HC/A was the anthropometric parameter with the greatest explanatory power in SA variance and was significantly greater in high school graduates who were 17 y old (r = 0.350; p < 0.001; r2 = 0.122) than in elementary school children, who were 6 y old (r = 0.227; p < 0.001; r2 = 0.049), with a relative risk of 2.1 and 1.5, respectively. The explanatory power of W/A and H/A in SA variance was significantly decreased, and no significant differences were observed among high school students. These findings confirm that HC/A is the most important anthropometric parameter associated with SA. Educational selectivity apparently relates to HC/A, and not to W/A or H/A. These results may be useful in planning nutritional and educational policies.