Asymmetric synthesis and evaluation of a hydroxyphenylamide voltage-gated sodium channel blocker in human prostate cancer xenografts.

Voltage-gated sodium channels are known to be expressed in neurons and other excitable cells. Recently, voltage-gated sodium channels have been found to be expressed in human prostate cancer cells. α-Hydroxy-α-phenylamides are a new class of small molecules that have demonstrated potent inhibition of voltage-gated sodium channels. The hydroxyamide motif, an isostere of a hydantoin ring, provides an active scaffold from which several potent racemic sodium channel blockers have been derived. With little known about chiral preferences, the development of chiral syntheses to obtain each pure enantiomer for evaluation as sodium channel blockers is important. Using Seebach and Frater's chiral template, cyclocondensation of (R)-3-chloromandelic acid with pivaldehyde furnished both the cis- and trans-2,5-disubsituted dioxolanones. Using this chiral template, we synthesized both enantiomers of 2-(3-chlorophenyl)-2-hydroxynonanamide, and evaluated their ability to functionally inhibit hNa(v) isoforms, human prostate cancer cells and xenograft. Enantiomers of lead demonstrated significant ability to reduce prostate cancer in vivo.

Voltage-gated sodium channel blockers as cytostatic inhibitors of the androgen-independent prostate cancer cell line PC-3.

The recent discovery of sodium (Na(+)) channel expression in human prostate cancer (PCa) cells led us to investigate the potential use of neuronal Na(+) channel blockers as inhibitors of PCa cells. Our initial studies discovered two classes of Na(+) channel blockers that were effective inhibitors of PCa cell proliferation. Both hydroxyamides (compounds 1 and 4) and a hydantoin (compound 5) were shown to inhibit the androgen-independent PCa cell line PC-3 in vitro. Electrophysiology showed that all compounds functionally block brain type II voltage-gated Na(+) channels (Nav1.2) expressed in Xenopus laevis oocytes. Long-term growth assays in androgen-independent PC-3 cells showed remarkable inhibition of cell growth, with cells growing to a maximum of 30% of controls with analogue 1. Further, our analogues demonstrated only marginal impact on cell viability over the same treatment interval.

Facile synthesis of an azido-labeled thalidomide analogue.

[reaction: see text] A five-step synthesis of an azido-thalidomide analogue is presented. The sequence requires cheap and readily available starting materials and reagents, and only two steps require purification. Additionally, the azido-labeled analogue possesses activity comparable to that of thalidomide in inhibiting the proliferation of human microvascular endothelial cells, thus providing impetus for its use as a potential photoaffinity label of thalidomide.

Transesophageal Echocardiographic Detection of Malignant Lymphoma.

Transesophageal echocardiography (TEE) is an excellent method for visualizing pathology of the mediastinum. We present a case in which TEE detected an unsuspected lymphoma posterior to the descending thoracic aorta in a man suspected of having endocarditis. This case illustrates the advantages of TEE over transthoracic echocardiography in examining the mediastinum and the importance of performing a complete TEE examination.

Developing lipid nanoparticle-based siRNA therapeutics for hepatocellular carcinoma using an integrated approach.

Successful siRNA therapeutics requires the optimal integration of multiple components, including an efficient delivery system, a disease indication that is appropriate for siRNA-based therapy, and a potent and nontoxic siRNA against a robust therapeutic target. Although all currently available delivery systems have limitations, it is important to recognize that a careful selection of the disease indication, therapeutic target, and siRNA molecule could partially compensate for deficiencies associated with the delivery system and makes it possible to advance a therapeutic siRNA regimen. In this study, we present the development of siRNA therapeutics for hepatocellular carcinoma using an integrated approach, including the development of an efficient lipid nanoparticle delivery system, the identification of a robust therapeutic target that does not trigger liver toxicity upon target knockdown, and the selection of potent and nonimmunogenic siRNA molecules against the target. The resulting siRNA-containing lipid nanoparticles produced significant antitumor efficacy in orthotopic hepatocellular carcinoma models, and, thus, represent a promising starting point for the development of siRNA therapeutics for hepatocellular carcinoma.

Expression of Voltage-Gated Sodium Channel Nav1.8 in Human Prostate Cancer is Associated with High Histological Grade.

Voltage-gated sodium (Nav) channels are required for impulse conductance in excitable tissues. Navs have been linked to human cancers, including prostate. The expression and distribution of Nav isoforms (Nav1.1-Nav1.9) in human prostate cancer are not well established. Here, we evaluated the expression of these isoforms and investigated the expression of Nav1.8 in human prostate cancer tissues. Nav1.8 was highly expressed in all examined cells. Expression of Nav1.1, Nav1.2, and Nav1.9 were high in DU-145, PC-3 and PC-3M cells compared to LNCaP (hormone-dependent), C4-2, C4-2B, and CWR22Rv-1 cells. Nav1.5 and Nav1.6 were expressed in all cells examined. Nav1.7 expression was absent in PC-3M and CWR22Rv-1, but expressed in the other cells examined. Immunohistochemistry revealed intensive Nav1.8 staining correlated with more advanced pathologic stage of disease. Increased intensity of nuclear Nav1.8 correlated with increased Gleason grade. Our results revealed that Nav1.8 is universally expressed in human prostate cancer cells. Nav1.8 expression statistically correlated with pathologic stage (P=0.04) and Gleason score (P=0.01) of human prostate tissue specimens. The aberrant nuclear localization of Nav1.8 with advanced prostate cancer tissues warrant further investigation into use of Nav1.8 as a potential biomarker to differentiate between early and advanced disease.

Thalidomide analogues demonstrate dual inhibition of both angiogenesis and prostate cancer.

The identification of agents with antiproliferative activity against endothelial cells has significant value for the treatment of many angiogenesis-dependent pathologies. Herein, we describe the discovery of a series of thalidomide analogues possessing inhibitory effects against both endothelial and prostate cancer cells. More specifically, several analogues exhibited low micromolar to mid-nanomolar potency in the inhibition of human microvascular endothelial cell (HMEC) proliferation, both in the presence and absence of vascular endothelial growth factor (VEGF), with the tetrafluorophthalimido class of compounds demonstrating the greatest potency. Additionally, all the compounds were screened against two different androgen independent prostate cancer cell lines (PC-3 and DU-145). Again, the tetrafluorophthalimido analogues exhibited the greatest effect with GI(50) values in the low micromolar range. Thalidomide was found to demonstrate selective inhibition of androgen receptor positive LNCaP prostate cancer cells. Furthermore, we showed that, as an example, tetrafluorophthalimido analogue 19 was able to completely inhibit the prostate specific antigen (PSA) secretion by the LNCaP cell line, while thalidomide demonstrated a 70% inhibition. We have also demonstrated that a correlation exists between HMEC and prostate cancer cell proliferation for this structural class. Altogether, our study suggests that these analogues may serve as promising leads for the development of agents that target both androgen dependent and independent prostate cancer and blood vessel growth.