2-Methoxyestradiol (2ME2) is an antitumoral and antiangiogenic compound that inhibits hypoxia-inducible factor (HIF)-1, a key regulator of the hypoxic response that promotes tumor progression. HIF-1alpha, the regulated subunit of HIF-1, is overexpressed in premalignant, cancerous and metastatic lesions of prostate. Endothelin (ET)-1 is a HIF target gene and one that plays an important role during prostate bone metastasis via its interaction with endothelin A (ET(A)) receptor. We reasoned that 2ME2 combined with an ET(A) receptor antagonist would induce potent cytotoxic effects in prostate cancer cells.
PC-3 and LNCaP cells were grown alone or cocultured with human osteoblasts. The cells were treated with 2ME2, with an ET(A) receptor antagonist (BQ-123) or with combinations of both compounds. The cells were then evaluated for cytotoxicity, HIF-1alpha protein expression and HIF-1 transcriptional activity.
The combination of 2ME2 with BQ-123 induced synergistic cytotoxic effects in prostate cancer cells and in their cocultures with osteoblasts. No synergism was observed when 2ME2 was combined with the ET(B) selective antagonist, BQ-788. These results correlated with inhibition of HIF-1alpha protein expression, HIF-1 transcriptional activity, and PSA mRNA expression.
The ET(A) receptor antagonist was capable of potentiating the cytotoxic effects of 2ME2 in prostate cancer cells. These effects were apparently mediated through the inhibition of the HIF-1 pathway. Our in vitro data strengthen the rationale for using 2ME2 in combination with ET(A) receptor antagonists for the treatment of metastatic prostate cancer.
"The anti-angiogenic and anti-tumoral estrogen metabolite 2-methoxyestradiol (2ME) has been shown to inhibit HIF-1. Furthermore, the combination of 2ME with the endothelin-A receptor antagonist BQ-123 is associated with inhibition of HIF-1 protein expression, HIF-1 transcriptional activity and prostate specific antigen mRNA expression in prostate cancer cells . Systemic treatment with 2ME suppress HIF-1 expression in vivo and results in a decreased downstream expression of VEGF, phosphoglycerate kinase and GLUT1 in endometrial lesions . "
[Show abstract][Hide abstract] ABSTRACT: Cancer cells, as with most mammalian cells, depend on a continuous supply of glucose; not only as a precursor of glycoproteins, triglycerides and glycogen, but also as an important source of energy. This review concentrates on GLUT transporter expression in both normal and cancerous classical sex-steroid hormone tissues (i.e. breast, uterus, ovary, testis and prostate, among others). Given the importance of estrogen, progesterone and androgens in carcinogenesis, as well as in survival and propagation of these cancers, this review also highlights the current literature on hormone regulation of glucose transporters and on the role of hypoxia in their expression. Given the recent explosion of information on the newer GLUT6-12 family members, a brief overview on their function and general expression has been included. Finally, an insight into the use of glucose transporters as markers of cancer progression and clinical outcome is also discussed.
Current Vascular Pharmacology 11/2009; 7(4):534-48. DOI:10.2174/157016109789043928 · 2.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The endothelin system comprises the three peptide hormones endothelin (ET)-1, -2, -3, their G protein-coupled receptors, endothelin-A-receptor (ET(A)R) and endothelin-B-receptor (ET(B)R), and the enzymes of endothelin biosynthesis and degradation. In the past two decades, an impressive amount of data has been accumulated investigating the role of the endothelin system in a variety of malignancies. In many cancers, ET-1/ET(A)R interaction induces proliferation, angiogenesis, antiapoptosis and resistance to chemotherapy. Data indicate a pivotal role of the endothelin system in tumorigenesis, local progression and metastasis. Subsequently, novel drugs have been designed inhibiting ET-1 biosynthesis or ET(A)R interaction. A wide range of preclinical data is available on the role of ET(A)R antagonists in gynecological, urological and breast cancers providing evidence for their antiangiogenic, proapoptotic and growth inhibitory effects. Of particular interest is the anti-invasive and antimetastatic efficacy of ET(A)R antagonists and synergism when co-administered with established cancer therapies. Data indicate a future role of ET(A)R antagonists in oncologic therapies.
[Show abstract][Hide abstract] ABSTRACT: New, effective therapies for castration-resistant prostate cancer are needed to treat this lethal form of the disease. Through an understanding of the biology of endothelin-1 and the endothelin receptors (the endothelin axis) in prostate cancer, this axis has emerged as a promising target for therapeutic intervention. Clinical trials of potent, selective, or specific endothelin receptor A subtype (ETA) antagonists have demonstrated clinical activity, but such agents have not yet been approved for the treatment of prostate cancer. These generally well-tolerated, oral agents are ideal for chronic administration. This chapter will discuss the biology of the endothelin axis, several of the preclinical observations supporting the therapeutic rationale, and some of the available clinical trial data on this promising new approach.
European Urology Supplements 01/2009; 8(1):20-28. DOI:10.1016/j.eursup.2008.10.004 · 3.37 Impact Factor
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