Oncogenic LMO3 Collaborates with HEN2 to Enhance Neuroblastoma Cell Growth through Transactivation of Mash1

Expression of Mash1 is dysregulated in human neuroblastoma. We have also reported that LMO3 (LIM-only protein 3) has an oncogenic potential in collaboration with neuronal transcription factor HEN2 in neuroblastoma. However, the precise molecular mechanisms of its transcriptional regulation remain elusive. Here we found that LMO3 forms a complex with HEN2 and acts as an upstream mediator for transcription of Mash1 in neuroblastoma. The high levels of LMO3 or Mash1 mRNA expression were significantly associated with poor prognosis in 100 primary neuroblastomas. The up-regulation of Mash1 remarkably accelerated the proliferation of SH-SY5Y neuroblastoma cells, while siRNA-mediated knockdown of LMO3 induced inhibition of growth of SH-SY5Y cells in association with a significant down-regulation of Mash1. Additionally, overexpression of both LMO3 and HEN2 induced expression of Mash1, suggesting that they might function as a transcriptional activator for Mash1. Luciferase reporter assay demonstrated that the co-expression of LMO3 and HEN2 attenuates HES1 (a negative regulator for Mash1)-dependent reduction of luciferase activity driven by the Mash1 promoter. Chromatin immunoprecipitation assay revealed that LMO3 and HEN2 reduce the amount of HES1 recruited onto putative HES1-binding sites and E-box within the Mash1 promoter. Furthermore, both LMO3 and HEN2 are physically associated with HES1 by immunoprecipitation assay. Thus, our present results suggest that a transcriptional complex of LMO3 and HEN2 may contribute to the genesis and malignant phenotype of neuroblastoma by inhibiting HES1 which suppresses the transactivation of Mash1

Bilateral common carotid artery ultrasound for prediction of incident strokes using intima-media thickness and external diameter: an observational study

BACKGROUND: External common carotid artery (CCA) diameter and intima-media thickness (IMT) are independently associated with incident stroke and other cardiovascular events. Arterial geometry such as large IMT and large diameter may reflect vulnerable plaques and so impact stroke risk. Finally, arterial changes that exist bilaterally may increase stroke risk. METHOD: We studied middle-aged men and women (n=7276) from a prospective observational study who had right (R) and left (L) CCA IMT and external diameters measured via B-mode ultrasound (1987–89) in order to categorize CCA geometry. Using side- and gender-specific IMT and diameter medians, we categorized each measurement as large (≥ median) vs. not large (< median) and defined four geometries: both IMT and diameter were large, only one parameter was large, or neither was large (reference group). Participants were followed for first time stroke through December 31, 1999. We used proportional hazards models to assess associations between right and left CCA geometries with new stroke. We also calculated positive and negative likelihood ratios (+LR and -LR) for CCA bilateral phenotypes as a measure of diagnostic accuracy. RESULTS: Presence of both large CCA IMT and large diameter on one side was associated with strong stroke risk even after risk factor adjustment (men: RCCA hazard ratio [HR]=3.7 95% confidence interval [CI]=1.9-7.4; LCCA HR=2.4 95% CI=1.4-4.4; women: RCCA HR=4.0 95% CI=1.5-10.5; LCCA HR=5.7 95% CI=1.7-19.0). Presence of both large IMT and large diameter bilaterally was the strongest predictor of stroke identifying 64% of women and 44% of men who developed strokes. This phenotype showed potential for predicting stroke among individuals (women: +LR=3.1, 95% CI=2.6-3.8; men: +LR=2.3, 95% CI=1.8-2.8). CONCLUSION: Bilateral carotid artery geometries may be useful for stroke risk prediction