I have a bunch of microRNA probe names (e.g., hsa-let-7a-5p, hsa-let-7b-5p) including MIMAT identifiers. The data are from Nanostring experiment. The question is how to map these probe names to Entrez Gene IDs to run KEGG overrepresentation analysis on the data.

First I have a simple mapping from miRBase to Entrez:

humanMirnaIdx <- grep("hsa", mappedkeys(targetscan.Hs.egMIRNA))
humanMirna <- mappedkeys(targetscan.Hs.egMIRNA)[humanMirnaIdx]
humanMirnaFamilies <- unlist(mget(humanMirna, targetscan.Hs.egMIRBASE2FAMILY))
humanMirnaTargets <- mget(humanMirnaFamilies, revmap(targetscan.Hs.egTARGETS))
names(humanMirnaTargets) <- humanMirna

and then I use mapping function to do actual mapping:

mirbase2entrez <- function(mirnas, human_mirna_targets) {
  my_list <- list()
  for (i in mirnas) {
    my_list[[i]] <- human_mirna_targets[[i]]
  }
  entrez_ids <- as.numeric(unlist(my_list))
  return(entrez_ids)
}

mirbase2entrez(mirnas = "hsa-let-7a-5p", human_mirna_targets = humanMirnaTargets)

I wonder if described approach is appropriate? If not, I kindly as for any pointers or references.