Date

5-2009

Advisor

Dorothy Teegarden

Department

Foods and Nutrition

Major

Dietetics

Keywords

F&N, Viatmin D, Vascular Endothelial Growth Factor (VEGF), Hypoxia Inducible Factor-1a (HIF-1a), Prolyl Hydroxylase (PHD)

Abstract

Breast cancer is one of the most prevalent forms of cancer among American women. Vitamin D has been shown to reduce the risk of developing breast cancer, in part by preventing the formation of new blood vessels (termed angiogenesis) within tumors.

Vascular Endothelial Growth Factor (VEGF), a potent angiogenic factor, has been shown to be regulated by the active form of vitamin D, 1,25- dihydroxyvitamin D (1,25(OH)2D). It has been proposed that 1,25(OH)2D does not directly decrease the expression of VEGF, but rather acts indirectly through Hypoxia Inducible Factor-1α (HIF-1α), a direct transcriptional regulator of VEGF. 1,25(OH)2D may impact HIF-1α in one of two ways: gene transcription or stability of the protein, which is degraded through the actions of

Prolyl Hydroxylase (PHD). The purpose of this study was to determine the impact of 1,25(OH)2D on VEGF, HIF-1α, and PHD mRNA expression in MCF10A breast epithelial cells which are untransformed (LXSN) or which contain the ErbB2 oncogene. ErbB2 is an oncogene that is commonly overexpressed and associated with an increased aggressiveness in breast cancer. The MCF10A are a model of multistage carcinogenesis, models that are important to use when studying cancer prevention. The hypothesis of this study is that 1,25(OH)2D decreases the gene expression of VEGF and HIF-1α, and increases the gene expression of PHD in untransformed breast epithelial cells and breast epithelial cells transfected with ErbB2.

Treatment of LXSN cells with increasing concentrations of 1,25(OH)2D (1 nM, 10 nM, and 100 nM) for 24 hours resulted in increasing concentrations of VEGF mRNA and decreasing concentration of PHD mRNA levels compared to the vehicle control. However, these differences were not significant (p>0.05) except at a high dose of 1,25(OH)2D (100 nM). Increasing doses of 1,25(OH)2D did not significantly alter HIF-1α mRNA abundance (p>0.05) compared to the vehicle control.

Treatment of the ErbB2- containing cells with the same increasing concentrations of 1,25(OH)2D showed no significant difference in the concentration of VEGF or HIF-1α mRNA (p>0.05) compared to the vehicle control. The PHD mRNA expression decreased with increasing concentrations of 1,25(OH)2D, however this was only significant (p>0.05) at the high dose of 1,25(OH)2D (100 nM). These results suggest that in untransformed MCF10A breast epithelial cells, 1,25(OH)2D increases the expression of VEGF mRNA at high doses, but not through an increased expression of HIF-1α mRNA. In the MCF10A breast epithelial cells transfected with ErbB2, 1,25(OH)2D had no significant impact on the expression of VEGF or HIF- 1α mRNA.

Download

Share

COinS