Abstract: Disclosed herein are methods of treating a tumor in a subject, including administering to the subject one or more miRNA nucleic acids or variants (such as mimics or mimetics) thereof with altered expression in the tumor. Also disclosed herein are compositions including one or more miRNA nucleic acids. In some examples, the miRNA nucleic acids are modified miRNAs, for example, and miRNA nucleic acid including one or more modified nucleotides and/or a 5?-end and/or 3?-end modification. In particular examples, the modified miRNA nucleic acid is an miR-30a nucleic acid. Further disclosed herein are methods of diagnosing a subject as having a tumor with altered expression of one or more miRNA nucleic acids. In some embodiments, the methods include detecting expression of one or more miRNAs in a sample from the subject and comparing the expression in the sample from the subject to a control.