Hi Hiral,

in general, there is a certain likelihood of residual DNA-contamination in your RNA isolate, regardless of the method you chose to use. So yes, DNase treatment is a good idea. When I'm not mistaken, to can perform on-column DNase treatment with the aforementioned kit. The Quantitect qiagen cDNA Kit containes a gDNA wipe-out buffer with they claim gets rid of DNA contamination. However, if your primers that you use for your expression analysis are exon-exon spanning, gDNA should not be a problem.

Best

Soner