Worldwide, cancer persists as one of the most important diseases that affect the human being. The knowledge on the molecular bases of cancer generated during the last decades has been successfully translated into small but significant gains in overall cancer survival rates due to better primary prevention measures, improved diagnostic methods and the development of more effective and specific therapies, collectively termed "molecular targeted therapies". In the context of these new forms of treatment, epigenetic or transcriptional cancer therapy is clearly promising.
Epigenetics refers to the function of DNA that does not depend on the coding DNA sequence itself but on the accessory molecules and mechanisms affected by DNA. It is known that epigenetic alterations are equally if not more important than classical genetic alterations to disrupt the function of tumour suppressor genes. The two most studied epigenetic aberrations common to all types of cancer are DNA hypermethylation and histone deacetylation, which cooperate to silence the expression of tumour suppressor genes, just as gene mutations and gene deletions do. The big difference between these two alternative ways that tumour cells use to inactivate tumour suppressor genes is that, while the reversal of genetic alterations is technically almost unfeasible in clinical scenarios, the function of these epigenetically inactivated suppressor genes is easily reactivated by pharmacological means. In this inaugural issue of PLoS ONE, Dr. Dueas-Gonzalez's group from the Instituto de Investi gaciones Biomdicas of the Universidad Nacional Autnoma de Mxico and the Instituto Nacional de Cancerologa, Mexico, demonstrate, for the first time, that a combination of a DNA methylation and a histone deacetylase inhibitor, can reactivate the expression of more than a thousand genes in primary tumours of breast cancer patients.