I have experimental evidence to suggest a miRNA downregulates a gene. When I overexpress the miRNA the expression of the gene decreases after 48 hours by RNA-seq. This was validated with qPCR and western blot in the same cell line and also in independent models.

To test if the regulation is direct I want to perform a luciferase reporter assay.

I used a few online prediction tools to see if there is a motif for the miRNA in the 3'UTR of the gene. According to miRanda-miRSVR (microRNA.org) there is a predicted motif (mirSVR score: -0.7814 PhastCons score: 0.7297) but other commonly used tools such as TargetScan and miRDB do not predict an interaction. I understand different tools use different parameters, and the more likely interactions are those that are stringently detected by multiple methods.

Based on my experimental evidence, and the fact that the motif is detected using miRanda only, is this good enough justification for investing the time and cost of performing luciferase assays?

Thanks in advance.