Provided are methods of treating breast cancer in a subject in need thereof comprising administering to the subject an effective amount of an inhibitor of miR-105 or an inhibitor of miR-122 are provided. Also provided herein are methods of determining a level of miR-105 or a level of miR-122 in a subject that has or is at risk for developing breast cancer. The method includes obtaining a biological sample from the subject and determining a level of miR-105 or a level of miR-122 or a combination thereof in the biological sample, wherein a higher level of miR-105 or miR-122 as compared to a control indicates that the subject has or is at risk of developing breast cancer.