A good estrogen

2-Methoxyestradiol and Its Combination with a Natural Compound, Ferulic Acid, Induces Melanoma Cell Death via Downregulation of Hsp60 and Hsp90

Melanoma is an aggressive type of skin cancer with one of the highest mortality rates. Notably, its incidence in the last few decades has increased faster than any other cancer. Therefore, searching for novel anticancer therapies is of great clinical importance. In the present study, we investigated the anticancer potential of 2-methoxyestradiol, potent chemotherapeutic, in the A375 melanoma cellular model. In order to furthermore evaluate the anticancer efficacy of 2-methoxyestradiol, we have additionally combined the treatment with a naturally occurring polyphenol, ferulic acid. The results were obtained using the melanoma A375 cellular model. In the study, we used MTT assay, flow cytometry, and western blot techniques. Herein, we have evidenced that the molecular mechanism of action of 2-methoxyestradiol and ferulic acid is partly related to the reduction of Hsp60 and Hsp90 levels and the induction of nitric oxide in the A375 melanoma cell model, while no changes were observed in Hsp70 expression after 2-methoxyestradiol and ferulic acid treatment separately or in combination. This is especially important in case of chemoresistance mechanisms because the accumulation of Hsp70 reduces induction of cancer cell death, thus decreasing antitumour efficacy.

Chemistry of the cortistatins--a novel class of anti-angiogenic agents

Synthetic efforts culminating the construction of several highly advanced intermediates, and completed syntheses of the recently disclosed cortistatin family of anti-proliferative agents are described in this perspective.

Distinct tumor stage-specific inhibitory effects of 2-methoxyestradiol in a breast cancer mouse model associated with Id-1 expression

2-Methoxyestradiol (2ME(2)), a metabolite of 17-beta-estradiol, inhibits angiogenesis and has additional antitumor activities. We have analyzed the tumor stage-specific effects of 2ME(2) in the C3(1)/Tag transgenic mouse model for breast cancer, which spontaneously develops estrogen receptor-negative mammary tumors following a predictable progression of lesion formation. When given either as a therapeutic agent in established tumors (late intervention study) or in mice with pre-invasive mammary lesions (early intervention study), tumor growth was reduced by 60% compared with untreated controls and was associated with an induction of apoptosis. In a prevention study, a significant reduction in mammary intraepithelial neoplasia (MIN) lesions was observed in animals beginning treatment at 6 weeks of age, before the appearance of histopathologic abnormalities. However, although 2ME(2) reduced the number of MIN lesions in the prevention study, a paradoxical increase in tumor multiplicity and growth rate was observed. This was associated with unusual cystic tumor formation, in which significant central necrosis was observed, surrounded by an outer region of proliferative tumor cell growth. The characteristics of the cystic tumor formation in mice treated with 2ME(2) at early ages are consistent with an impaired angiogenic response as observed in mice deficient for inhibitor of differentiation (Id-1). We further show that Id-1 expression is negatively regulated by 2ME(2), which may be an additional mechanism for the antiangiogenic effect of 2ME(2). Although 2ME(2) significantly reduced tumor growth at late stages, these results also suggest that altered tumor morphology and accelerated tumor growth may occur if 2ME(2) is administered in a prevention setting for prolonged periods.

SAR studies of 2-methoxyestradiol and development of its analogs as probes of anti-tumor mechanisms

The major estrogen metabolite 2-methoxyestradiol (2ME) has been shown to target tumor cells without severe side effects and is currently being evaluated in clinical trials for several types of cancer. Despite its promise for use in clinical setting, the mechanism(s) by which 2ME exerts its anti-tumor activity is not clearly defined at this time. Employing organic chemistry tools, we synthesized 2ME analogs with which 2ME affinity column was prepared, enabling us to detect a protein that selectively interacts with 2ME. This 2ME analog will be useful as a probe to identify the biological target(s) of 2ME and study their functions in tumor cells.

Safety and pharmacokinetics of intravitreal 2-methoxyestradiol implants in normal rabbit and pharmacodynamics in a rat model of choroidal neovascularization

Choroidal neovascularization (CNV) is the leading cause of severe vision loss associated with age-related macular degeneration. As the pathogenesis of CNV formation is better understood, mechanism-based therapies, including the use of antiangiogenesis inhibitors, have been investigated. 2-methoxyestradiol (2ME2), an endogenous metabolite of estradiol, has been shown in the chick allantoic membrane model and the corneal micropocket assay to have antiangiogenic properties. The authors sought to determine the safety and pharmacokinetics of sustained-release intravitreal 2ME2 implants in normal rabbit and their efficacy in a rat model of CNV. 2ME2 implants were constructed using two designs: implant A, a silicone-based reservoir implant for the rabnbit eye, and implant B, a microimplant matrix design for the rat eye. In vitro release rates of both implants were determined. New Zealand white (NZW) rabbits had implant A placed in the vitreous cavity of one eye and the ocular toxicity was evaluated by clinical examination, serial electroretinography (ERG), and histopathology over a 28 week period. The steady state clearance of 2ME2 in the rabbit eye was calculated from in vivo release rates divided by steady state vitreous concentrations. A CNV model in the Brown-Norway rat was performed by injecting an adenoviral vector encoding human vascular endothelial growth factor in the subretinal space. Following the injection, a 2ME2 or sham (no drug) microimplant was placed in the vitreous cavity. Animals were killed over a 3 week period and the eyes examined for CNV by histopathology. Results showed that following a short burst, the release rate of implant A followed zero-order kinetics, typical of reservoir devices, and the cumulative release of implant B was proportional to the square root of time, as expected for a matrix delivery device. The safety studies in normal rabbit showed no ocular toxicities by clinical examination, ERG, and histopathology. Pharmacokinetic evaluation in the rabbit showed mean 2ME2 vitreous levels within the therapeutic range for the inhibition of endothelial cell proliferation. The experimental rat model showed a significant reduction in CNV in eyes treated with the 2ME2 implant. In conclusion, sustained-release 2ME2 intravitreal implants, which can be designed to deliver potentially therapeutic vitreous levels of 2ME2 for an extended period of time, appeared to be safe in normal rabbit and effective in a rat model of CNV. Sustained-release 2ME2 intravitreal implants may hold promise in the treatment of recurrent CNV refractory to standard therapy.