As you know, each miR is encoded by a special gene being regulated by some transcription factor(s). To do what you want, you must know the name of this TF and how its activity depends on any compounds of low molecular weight (inorganic cations and anions, polyamines, etc). If you know this, you can simply create deficient or odd mode as to the needed regulatory agent (using dietary or injectional introduction of an agent itself, dietary deprivation, dietary or injectional introduction of the corresponding enzyme inhibitors) and make what you want.