Changing the TextAlignment property of the GridViewExpressionColumn doesn't refresh the cells, thus the change is not visible in the UI.

To work this around, remove and add again the corresponding column in the Columns collection of RadGridView. Or define a CellTemplate and use a TextBlock control with its TextAlignment bound to the column's property.

<telerik:GridViewExpressionColumn.CellTemplate>
	<DataTemplate>
		<TextBlock Text="{Binding}" 
				   TextAlignment="{Binding RelativeSource={RelativeSource AncestorType=telerik:GridViewCell}, Path=Column.TextAlignment}"  />
	</DataTemplate>
</telerik:GridViewExpressionColumn.CellTemplate>