Development and characterization of a novel C-terminal inhibitor of Hsp90 in androgen dependent and independent prostate cancer cells.

BACKGROUND: The molecular chaperone, heat shock protein 90 (Hsp90) has been shown to be overexpressed in a number of cancers, including prostate cancer, making it an important target for drug discovery. Unfortunately, results with N-terminal inhibitors from initial clinical trials have been disappointing, as toxicity and resistance resulting from induction of the heat shock response (HSR) has led to both scheduling and administration concerns. Therefore, Hsp90 inhibitors that do not induce the heat shock response represent a promising new direction for the treatment of prostate cancer. Herein, the development of a C-terminal Hsp90 inhibitor, KU174, is described, which demonstrates anti-cancer activity in prostate cancer cells in the absence of a HSR and describe a novel approach to characterize Hsp90 inhibition in cancer cells. METHODS: PC3-MM2 and LNCaP-LN3 cells were used in both direct and indirect in vitro Hsp90 inhibition assays (DARTS, Surface Plasmon Resonance, co-immunoprecipitation, luciferase, Western blot, anti-proliferative, cytotoxicity and size exclusion chromatography) to characterize the effects of KU174 in prostate cancer cells. Pilot in vivo efficacy studies were also conducted with KU174 in PC3-MM2 xenograft studies. RESULTS: KU174 exhibits robust anti-proliferative and cytotoxic activity along with client protein degradation and disruption of Hsp90 native complexes without induction of a HSR. Furthermore, KU174 demonstrates direct binding to the Hsp90 protein and Hsp90 complexes in cancer cells. In addition, in pilot in-vivo proof-of-concept studies KU174 demonstrates efficacy at 75 mg/kg in a PC3-MM2 rat tumor model. CONCLUSIONS: Overall, these findings suggest C-terminal Hsp90 inhibitors have potential as therapeutic agents for the treatment of prostate cancer.

Activity of anticancer agents in a three-dimensional cell culture model.

Cell-monolayer-based assays for chemotherapeutic drug discovery have proven to be highly artificial compared with physiological systems. The objective of this study was to culture cancer cells in a simple 3-dimensional (3D) collagen gel model to study the antiproliferative activity of known lung cancer drugs. The validity of our 3D model was tested by measuring the activity of 10 lung cancer drugs (Paclitaxel, Alimta, Zactima, Doxorubicin, Vinorelbine, Gemcitabine, 17AAg, Cisplatin, and 2 experimental drugs from the University of Kansas [KU174 and KU363]) in 2 lung cancer cell lines (A549 and H358) and comparing the activity in a traditional 2-dimensional (2D) in vitro cellular assay. Both potency and efficacy of these drugs were calculated to evaluate the activity of the drugs. Our results demonstrate that the activity of these drugs showed significant differences when tested in 3D cultures, which varied with individual drugs and the cell line used for testing. For example, the cytotoxicity of Paclitaxel, KU174, Alimta, Zacitma, Doxorubicin, Vinorelbine, KU363, and 17AAg was significantly changed when tested in the 3D model, whereas the potency of Cisplatin and Gemcitabine in H358 cell line remained unaffected. A similar pattern, with some differences, was observed in A549 cells and is discussed in detail in this article. The observed differences in potency and efficacy of the cancer drugs in 3D models suggest that the biological implications of screening configurations should be taken into account to select superior cancer drug candidates in preclinical studies.

A dispensable role for P450(scc) in the overproduction of aldosterone in aldosterone-producing adenoma and idiopathic hyperaldosteronism in patients with primary aldosteronism.

Our previous study suggests that cytochrome P-450 carbon 17α-hydroxylase/17,20-lyase (P450(c17α)) correlated with the overproduction of aldosterone in aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA) in patients with primary aldosteronism. To further investigate if cytochrome P-450 cholesterol side-chain cleavage enzyme (P450(scc)) contributes to the overproduction of aldosterone in APA and IHA and if its mRNA expression differs in APA and IHA in patients with primary aldosteronism, we studied the expression of P450(scc) mRNA in APA and idiopathic hyperplastic nodules. Total RNA was extracted from APA of eight patients diagnosed as APA, idiopathic hyperplastic nodules of four patients diagnosed as IHA, seven normal adrenal glands and one normal muscle tissue. P450(scc) mRNA was examined by Northern blot analysis. No significant difference in P450(scc) mRNA was found among normal adrenal gland, APA or idiopathic hyperplastic nodules (P > 0.05). These results suggest that P450(scc) contributes little to the overproduction of aldosterone in APA and IHA and cannot be considered as a marker to differentiate between them in patients with primary aldosteronism.

A critical role of surgery in the treatment for paraneoplastic pemphigus caused by localized Castleman's disease.

Paraneoplastic pemphigus (PNP) is an autoimmune mucocutaneous disease associated with lymphoproliferative tumors, and sometimes with a very rare tumor, Castleman's disease (CD). PNP can present as a variety of dermatological diseases, and so far, only limited studies of PNP caused by CD have been reported, resulting in its higher possibility of misdiagnosis. Because of the variability of clinical presentation of PNP caused by CD, selection of the appropriate therapeutic approach remains unclear. To investigate the efficacy of surgery to patients with PNP caused by localized CD, the clinical, laboratory and pathological data of 5 patients with PNP caused by localized CD, 3 females and 2 males, aged 34 years (ranging from 29 to 42), with the tumor size from 6 x 4 x 4 cm(3) to 8 x 8 x 7 cm(3), located in the mediastinum (n = 3) and retroperitoneum (n = 2), were compared before and after surgery. All patients underwent surgery, and the diagnosis was confirmed by pathological examination. Surgery significantly improved mucosal lesions, cured skin lesions and decreased serum pemphigus autoantibody 6 months after surgery. Most patients were followed up for 6-48 months, and they all had no clinical or radiological recurrence and remain disease free. Therefore, surgery is an effective approach to cure patients with PNP caused by localized CD.