Therapeutic regulation of epigenetics in cancer treatment through drug delivery systems

Not only genetic but also epigenetic factors are closely associated with cancer, especially with its malignant evolution. Cancer therapies based on epigenetic modulation have therefore been proposed early on. However, it has produced significant efficacy only in patients with hematological malignancies rather than solid tumors, partly due to the inherent physicochemical properties of the drugs and the impediments to their reaching the tumor cells in vivo. As a result, a growing number of researches have been devoted to extending the use of epigenetic therapies to a wider range of solid tumor treatments by means of drug delivery strategies (DDSs). These studies have provided new insights into the application of epigenetic therapies for cancer and new ideas to address the poor outcome of epigenetic therapy in solid tumors through DDSs. Therefore, this review summarizes the epigenetic factors of cancer, the contribution of the designed DDSs to the anti-tumor treatments (especially solid tumors), the application of different anti-tumor epigenetic therapies based on DDSs, and finally analyses the potential problems in current anti-tumor epigenetic therapies and the great potential of DDSs in their future development.