Epigenetic treatment has been approved by regulatory agencies for haematological malignancies. The success observed in cutaneous lymphomas represents a proof of principle that similar results may be obtained in solid tumours. Several agents that interfere with DNA methylation-demethylation and histones acetylation/deacetylation have been studied, and some (such as azacytidine, decitabine, valproic acid and vorinostat) are already in clinical use. The aim of this review is to provide a brief overview of the molecular events underlying the antitumour effects of epigenetic treatments and to summarise data available on clinical trials that tested the use of epigenetic agents against solid tumours. We not only list results but also try to indicate how the proper evaluation of this treatment might result in a better selection of effective agents and in a more rapid development. We divided compounds in demethylating agents and HDAC inhibitors. For each class, we report the antitumour activity and the toxic side effects. When available, we describe plasma pharmacokinetics and pharmacodynamic evaluation in tumours and in surrogate tissues (generally white blood cells). Epigenetic treatment is a reality in haematological malignancies and deserves adequate attention in solid tumours. A careful consideration of available clinical data however is required for faster drug development and possibly to re-evaluate some molecules that were perhaps discarded too early.

The sex steroid hormone 17β-estradiol (E2) upregulates the levels of neuroglobin (NGB), a new neuroprotectant globin, to elicit its neuroprotective effect against H₂O₂-induced apoptosis. Several mechanisms could be proposed to justify the NGB involvement in E2 prevention of stress-induced apoptotic cell death. Here, we evaluate the ability of E2 to modulate the intracellular NGB localization and the NGB interaction with mitochondrial cytochrome c following the H₂O₂-induced toxicity. Present results demonstrate that NGB is expressed in the nuclei, mitochondria, and cytosol of human neuroblastoma SK-N-BE cells. E2, but not H₂O₂ treatment of SK-N-BE cells, reallocates NGB mainly at the mitochondria and contemporarily reduces the number of apoptotic nuclei and the levels of cleaved caspase-3. Remarkably, the E2 treatment strongly increases NGB–cytochrome c association into mitochondria and reduces the levels of cytochrome c into the cytosol of SK-N-BE cells. Although both estrogen receptors (ERα and ERβ) are expressed in the nucleus, mitochondria, and cytosol of SK-N-BE cells, this E2 effect specifically requires the mitochondrial ERβ activity. As a whole, these data demonstrate that the interception of the intrinsic apoptotic pathway into mitochondria (i.e., the prevention of cytochrome c release) is one of the pivotal mechanisms underlying E2-dependent NGB neuroprotection against H₂O₂ toxicity.

Physiological sex differences may influence metabolic status and then alter the onset of some diseases. According to recent studies, it is now well established that females are more protected from hypercholesterolemia-related diseases, such as cardiovascular diseases until menopause. Female protection from hypercholesterolemia is mediated by the hypolipidemic properties of estrogens, even if mechanisms underlying this protection remain still debated. Even though the regulatory mechanisms of cholesterol homeostasis maintenance are well known, few data are available on the supposed differences between male and female in these processes. So, the aim of this work was to define, through an in vivo study, the putative sex-dependent regulation of the processes underlying cholesterol homeostasis maintenance. We examined 3-hydroxy 3-methylglutaryl coenzyme A reductase and its regulatory protein network as well as the amount of low-density lipoprotein receptor and cholesterol. The study was conducted in the liver and plasma of male and female rats, on adults and during postnatal development, and on 17-β-estradiol-treated male rats. Our data support that physiological differences in proteins involved in cholesterol balance are present between the sexes and, in particular, 3-hydroxy 3-methylglutaryl coenzyme A reductase shows lower activity and expression in female and 17-β-estradiol-treated male rats than in adult untreated male. Our data suggest that sex differences in enzyme expression depend on variation in regulatory proteins and seem to be related to estrogen presence. This work adds new evidence in the complicated picture of sex-dependent cellular physiology and establishes a new role for reductase regulatory proteins as a link between estrogen protective effects and cholesterol homeostasis.