The RadChart does not support such functionality, however you can manually iterate through the labels of the axis and hide all the labels, except the ones which represent a data point present in the chart. Here is an example :
foreach (var series in this.RadChart1.DefaultView.ChartArea.DataSeries)
foreach (var dataPoint in series)
Don't forget to set the "resolution" of the axis by changing the AxisY.Step property to 1 (for example), because otherwise at 137, there won't be a label to hide. I have attached an image of the result that I get.