Bianca Nitzsche

Heat shock protein 90 is a promising target for effective growth inhibition of gastrointestinal neuroendocrine tumors

Treatment of gastroenteropancreatic neuroendocrine tumors (GEP-NET) is still unsatisfactory and innovative therapeutic approaches are urgently needed. Heat shock protein 90 (Hsp90) is overexpressed in a wide range of tumor types and is an emerging target for the treatment of cancer. However, the potential activity of Hsp90 inhibitors in GEP-NET has not yet been investigated. We studied the antineoplastic activity of the Hsp90 inhibitor IPI-504 on GEP‑NET cells, and characterized its mechanism of action. In human insulinoma (CM) and pancreatic carcinoid (BON) cells IPI-504 induced a dose-dependent growth inhibition by almost 70%. The antiproliferative effect of IPI-504 correlated with a reduction in protein levels of the IGF-1 receptor. Additionally, several proteins of the PI3K/AKT/mTOR pathway, downstream of IGF-1 receptor activation in GEP-NETs, were downregulated as a consequence of Hsp90 inhibition. Combination treatment of IPI-504 with mTOR- or AKT-inhibitors led to additive antiproliferative effects. In addition, effects of IGF-1 receptor tyrosine kinase inhibition were strongly enhanced by IPI-504. Cancer gene expression profiling and FACS analysis revealed that IPI-504 antiproliferative effects were due to both induction of cell cycle arrest and apoptosis. A modified chick chorioallantoic membrane (CAM) assay confirmed the antineoplastic activity of IPI-504 in GEP-NETs in vivo. In conclusion, this study showed that Hsp90 inhibition may be an attractive target for innovative GEP-NET treatment alone or in combination with either IGF-1R or mTOR inhibitors.

New 4-Maleamic Acid and 4-Maleamide Peptidyl Chalcones as Potential Multitarget Drugs for Human Prostate Cancer

ABSTRACTPurposeThe objective of this study was to investigate the effect of new 4-maleamic acid and 4-maleamide peptidyl chalcone derivatives against human prostate cancer in vitro and in vivo.MethodsFrom a series of 21 chalcones, the effects of the three best inhibitors of PC-3 and LNCaP cell viability on growth, including cell cycle changes, adhesion, migration, and cell invasion, as well as their ability to inhibit angiogenesis, clonogenic activity, and matrix metalloproteinases MMP-2 and MMP-9, were tested. The effects in vivo were studied in PC-3 and LNCaP xenografts.ResultsThree of the examined chalcones reduced cell viability in both cell lines in a strong dose- and time-dependent manner. An inhibition of the cell cycle progress was observed. These changes were accompanied with the inhibition of cell adhesion, migration, and invasion as well as with reduced neovascularization in chick embryos, tumor colony formation, and MMP-9 activity. The in vivo results demonstrated the strong activity of these structures as inhibitors of tumor development in nude mice compared to non-treated animals.ConclusionThe results suggest the multitarget efficacy of 4-maleamic acid and 4-maleamide peptidyl chalcones against human prostate cancer cells and emphasize the potential therapeutic relevance of these compounds.

AKT inhibition by triciribine alone or as combination therapy for growth control of gastroenteropancreatic neuroendocrine tumors.

Up-regulation of phosphatidylinositol-3-kinase (PI3K)-AKT signaling facilitates tumor cell growth and inhibits cell demise. The AKT-pathway also plays an important role in cytostatic therapy resistance and response to hypoxia and angiogenesis. Using real-time cell proliferation assay we examined the potency of triciribine in three distinct neuroendocrine gastrointestinal tumor cell lines. Also we investigated triciribines induction of apoptosis and effects on a broad range of cancer-associated gene products. Furthermore, we characterized the role of PTEN as a possible predictor of sensitivity to triciribine in GEP-NETs. We also looked for additive anti-neoplastic effects of triciribine when combined with conventional cytostatic drugs or other targeted drugs, affecting different molecules of the PI3K-AKT-pathway and we assessed the potency of triciribine to inhibit tumor growth in vivo, by using the chick chorioallantoic membrane assay. Treatment of insulinoma (CM) or gut neuroendocrine tumor cells (STC-1) with triciribine significantly reduced tumor cell growth by 59% and 65%, respectively. By contrast, the highly expressing PTEN carcinoid cell line BON did not respond, even at higher doses. Combinations of triciribine with classic cytostatic drugs as well as drugs targeting other molecules of the PI3K-AKT-pathway led to synergistic anti-proliferative effects. Additional in vivo-evaluations confirmed the anti-neoplastic potency of triciribine. Thus, our data show that inhibition the AKT-pathway potently reduces the growth of GEP-NET cells alone or in combination therapies. AKT inhibition may provide a rationale for future evaluations.

Effects of sorafenib on C-terminally truncated androgen receptor variants in human prostate cancer cells.

Recent evidence suggests that the development of castration resistant prostate cancer (CRPCa) is commonly associated with an aberrant, ligand-independent activation of the androgen receptor (AR). A putative mechanism allowing prostate cancer (PCa) cells to grow under low levels of androgens, is the expression of constitutively active, C-terminally truncated AR lacking the AR-ligand binding domain (LBD). Due to the absence of a LBD, these receptors, termed ARΔLBD, are unable to respond to any form of anti-hormonal therapies. In this study we demonstrate that the multikinase inhibitor sorafenib inhibits AR as well as ARΔLBD-signalling in CRPCa cells. This inhibition was paralleled by proteasomal degradation of the AR- and ARΔLBD-molecules. In line with these observations, maximal antiproliferative effects of sorafenib were achieved in AR and ARΔLBD-positive PCa cells. The present findings warrant further investigations on sorafenib as an option for the treatment of advanced AR-positive PCa.

Tetra-triethyleneoxysulfonyl substituted zinc phthalocyanine for photodynamic cancer therapy

Photodynamic therapy (PDT) has emerged as an effective and minimally invasive treatment option for several diseases, including some forms of cancer. However, several drawbacks of the approved photosensitizers (PS), such as insufficient light absorption at therapeutically relevant wavelengths hampered the clinical effectiveness of PDT. Phthalocyanines (Pc) are interesting PS-candidates with a strong light absorption in the favourable red spectral region and a high quantum yield of cancer cell destroying singlet oxygen generation. Here, we evaluated the suitability of tetra-triethyleneoxysulfonyl substituted zinc phthalocyanine (ZnPc) as novel PS for PDT. ZnPc-induced phototoxicity, induction of apoptosis as well as cell cycle arresting effects was studied in the human gastrointestinal cancer cell lines of different origin. Photoactivation of ZnPc-pretreated (1-10 μM) cancer cells was achieved by illumination with a broad band white light source (400-700 nm) at a power density of 10 J/cm(2). Photoactivation of ZnPc-loaded cells revealed strong phototoxic effects, leading to a dose-dependent decrease of cancer cell proliferation of up to almost 100%, the induction of apoptosis and a G1-phase arrest of the cell cycle, which was associated with decrease in cyclin D1 expression. By contrast, ZnPc-treatment without illumination did not induce any cytotoxicity, apoptosis, cell cycle arrest or decreased cell growth. Antiangiogenic effects of ZnPc-PDT were investigated in vivo by performing CAM assays, which revealed a marked degradation of blood vessels and the capillary plexus of the chorioallantoic membrane of fertilized chicken eggs. Based on our data we think that ZnPc may be a promising novel photosensitizer for innovative PDT.

N'-Formyl-2-(5-nitrothiophen-2-yl)benzothiazole-6-carbohydrazide as a potential anti-tumour agent for prostate cancer in experimental studies.

Benzothiazoles (BZTs) represent organic compounds with different biological actions. In this study we aimed to investigate ten newly synthesized BZT derivatives as potential anti‐tumour agents against prostate cancer in vitro and in vivo.

Effect of quinolinyl acrylate derivatives on prostate cancer in vitro and in vivo

SummaryQuinolines and acrylates are chemical compounds which were previously described as potential antitumor agents. In this study, a series of seven new quinolinyl acrylate derivatives were synthesized and evaluated against human prostate cancer cells PC-3 and LNCaP in vitro and in vivo. The most effective compound (E)-methyl 2-(7-chloroquinolin-4-ylthio)-3-(4 hydroxyphenyl) acrylate reduced the viability in both cell lines in a time- and dose-dependent manner. Inhibitory effects were also observed on the adhesion, migration, and invasion of the prostate cancer cells as well as on the neoangiogenesis, clonogenic and MMP-9 activity. The effect in vivo was studied in PC-3 xenografts in nude mice. The results were concordant with the in vitro effects and showed decreased tumor growth in treated animals compared to controls. The study suggests the multi-target efficacy of the quinolinyl derivate against human prostate cancer cells and supports its potential therapeutic usefulness.

Structure and hemodynamics of vascular networks in the chorioallantoic membrane of the chicken

The chick chorioallantoic membrane (CAM) is extensively used as an in vivo model. Here, structure and hemodynamics of CAM vessel trees were analyzed and compared with predictions of Murrays law. CAM microvascular networks of Hamburger-Hamilton stage 40 chick embryos were scanned by videomicroscopy. Three networks with ∼3,800, 580, and 480 segments were digitally reconstructed, neglecting the capillary mesh. Vessel diameters (D) and segment lengths were measured, and generation numbers and junctional exponents at bifurcations were derived. In selected vessels, flow velocities (v) and hematocrit were measured. Hemodynamic simulations, incorporating the branching of capillaries from preterminal vessels, were used to estimate v, volume flow, shear stress (τ), and pressure for all segments of the largest network. For individual arteriovenous flow pathways, terminal arterial and venous generation numbers are negatively correlated, leading to low variability of total topological and morphological pathway lengths. Arteriolar velocity is proportional to diameter (v∝D1.03 measured, v∝D0.93 modeling), giving nearly uniform τ levels (τ∝D0.05). Venular trees exhibit slightly higher exponents (v∝D1.3, τ∝D0.38). Junctional exponents at divergent and convergent bifurcations were 2.05 ± 1.13 and 1.97 ± 0.95 (mean ± SD) in contrast to the value 3 predicted by Murrays law. In accordance with Murrays law, τ levels are (nearly) maintained in CAM arterial (venular) trees, suggesting vascular adaptation to shear stress. Arterial and venous trees show an interdigitating arrangement providing homogeneous flow pathway properties and have preterminal capillary branches. These properties may facilitate efficient oxygen exchange in the CAM during rapid embryonic growth.

Microvascular Hemodynamics in the Chick Chorioallantoic Membrane

The microvasculature of the CAM in the developing chick embryo is characterized by interdigitating arteriolar and venular trees, connected at multiple points along their lengths to a mesh‐like capillary plexus. Theoretical modeling techniques were employed to investigate the resulting hemodynamic characteristics of the CAM.

Dynamic remodeling of arteriolar collaterals after acute occlusion in chick chorioallantoic membrane

After arteriolar occlusion, collaterals enlarge and initially elevated WSS normalizes. While most previous studies focused on endpoints of such adaptive changes in larger collaterals, the present investigation aimed to continuously determine the relation between WSS and diameter in microvascular collaterals during adaptive reactions.