Identification of a small-molecule inhibitor of Stat5a/b through structure-based screen for therapy development for prostate cancer

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Background: There are no effective treatments for metastatic or castration resistant prostate cancer. We have shown that transcription factor Stat5a/b is constitutively active in high-grade prostate cancer, but not in normal human prostate epithelium. Stat5a/b is active in 95% of clinical castration resistant prostate cancers, and the expression of active Stat5a/b in primary prostate cancer predicts early disease recurrence. Stat5a/b is critical for the viability of prostate cancer cells in vitro and for growth of prostate xenograft tumors in nude mice. Stat5a/b synergizes with androgen receptor (AR) and Stat5a/b promotes metastatic behavior of human prostate cancer cells in vitro and in vivo. Here, we hypothesize that Stat5a/b is a molecular target for rational drug design for prostate cancer.

Methods: We identified a small- molecule inhibitor of Stat5a/b dimerization by structure-based virtual screen from a database of 30 million chemical structures. The efficacy of the Stat5a/b inhibitor was determined by reporter gene assays, dimerization by co-immunoprecipitations, nuclear translocation by cytochemistry and binding to DNA by EMSA. Cell viability was analyzed by MTT assay.

Results: The novel Stat5a/b inhibitor IST5-002 inhibited transcriptional activity of Stat5a/b at IC50 of 1.5 μ M for Stat5a and 3.5 μ M for Stat5b, but not of Stat3 in prostate cancer cells. IST5-002 inhibited dimerization, nuclear translocation, and binding of Stat5a/b to the Stat5 DNA consensus sequence. Furthermore, IST5-002 inhibited expression of Stat5a/b target gene cyclin D1, and induced massive apoptosis of DU145, CWR22Rv1 and LNCaP human prostate cancer cells. IST5-002 blocked prostate cancer xenograft tumor growth in nude mice and induced death in clinical prostate cancers ex vivo in 3D organ cultures.

Conclusions: We have identified a small molecule Stat5a/b inhibitor IST5-002 for therapy development for prostate cancer. Future work will focus on chemical modifications of IST5-002 to achieve IC50 below 1 μ M and oral administration.

No significant financial relationships to disclose.

Mechanically enhanced microcapsules for cellular gene therapy

Microcapsules bearing a covalently cross-linked coating have been developed for cellular gene therapy as an improvement on alginate-poly(L-lysine)-alginate (APA) microcapsules that only have ionic cross-linking. In this study, two mutually reactive polyelectrolytes, a polycation (designated C70), poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride-co-2-aminoethyl methacrylate hydrochloride) and a polyanion (designated A70), poly(sodium methacrylate-co-2-(methacryloyloxy)ethyl acetoacetate), were used during the microcapsule fabrication. Ca-alginate beads were sequentially laminated with C70, A70, poly(L-lysine) (PLL), and alginate. The A70 reacts with both C70 and PLL to form a approximately 30 microm thick covalently cross-linked interpenetrating polymer network on the surface of the capsules. Confocal images confirmed the location of the C70/A70/PLL network and the stability of the network after 4 weeks implantation in mice. The mechanical and chemical resistance of the capsules was tested with a "stress test" where microcapsules were gently shaken in 0.003% EDTA for 15 min. APA capsules disappeared during this treatment, whereas the modified capsules, even those that had been retrieved from mice after 4-weeks implantation, remained intact. Analysis of solutions passing through model flat membranes showed that the molecular weight cut-off of alginate-C70-A70-PLL-alginate is similar to that of alginate-PLL-alginate. Recombinant cells encapsulated in APA and modified capsules were able to secrete luciferase into culture media. The modified capsules were found to capture some components of regular culture media used during preparation, causing an immune reaction in implanted mice, but use of UltraCulture serum-free medium was found to prevent this immune reaction. In vivo biocompatibility of the new capsules was similar to the APA capsules, with no sign of clinical toxicity on complete blood counts and liver function tests. The increased stability of the covalently modified microcapsules coupled with the acceptable biocompatibility and permeability demonstrated their potential for use as immunoisolation devices in gene therapy.

Possible involvement of brain tumour stem cells in the emergence of a fast-growing malignant meningioma after surgical resection and radiotherapy of high-grade astrocytoma: case report and preliminary laboratory investigation

The case of a 62-year old man diagnosed with radiation-induced meningioma (RIM) after treatment for astrocytoma with an unusually short latency period of 7 months is reported. The patient first presented with a 2-month history of memory decline. Magnetic resonance imaging (MRI) showed a tumour in the left parieto-temporal lobe. Gross total resection was performed and the tumour was confirmed to be an astrocytoma. The patient received cranial radiotherapy 2 weeks later, however 7 months after radiation treatment the patient presented with headache and vomiting. MRI showed massive meningeal enhancement in the left frontal lobe, which progressively enlarged. The patient's clinical condition deteriorated and a second craniotomy was performed with complete removal of the secondary tumour, which was shown to be a malignant meningioma. Immunohistochemical staining identified CD133-positive cells in both tumours. A rare fraction of brain tumour stem cells (BTSC) was isolated from the primary astrocytoma using a serum-free culture system, suggesting that BTSC may have been involved in the rapid emergence of RIM after resection and radiation of the primary astrocytoma.

Development of a cerebral microvascular dysplasia model in rodents

Normal vasculature development of the central nervous system is extremely important because patients with vascular malformations are at life-threatening risk for intracranial hemorrhage or cerebral ischemia. The etiology and pathogenesis of abnormal vasculature development in the central nervous system are unknown, and progress is hampered by the lack of animal models for human cerebrovascular diseases. Here, we report our current study on cerebral microvascular dysplasia (CMVD) development. Using vascular endothelial growth factor hyper-stimulation, we demonstrated that aberrant microvessels could be developed in the rodent brain under certain conditions (such as genetic deficient background, local cytokine and chemokine release, or exogenous vessel dilating stimulation) that may speed up focal angiogenesis and lead to cerebral vascular dysplasia.

Cranioplasty for patients developing large cranial defects combined with post-traumatic hydrocephalus after head trauma

BACKGROUND

Large cranial defects combined with hydrocephalus after decompressive craniectomy are a common, harsh reality among patients with head trauma. Typically, a shunt is first used to relieve the hydrocephalus. However, subsequently the patients may develop a severe sinking scalp flap over the skull defect before cranioplasty, which would make the procedure difficult.

METHODS

This problem was overcome by temporarily adjusting the shunt pressure using a programmable ventriculoperitoneal shunt tube, which allowed expansion of the depressed scalp flap and facilitated the subsequent cranioplasty. This study describes two patients who were treated for this problem after severe head trauma.

RESULTS

When performing a titanium mesh cranioplasty after a shunt, this new method facilitated the separation of the scalp from the underlying muscle or dura and obliterated the dead space between the titanium mesh and the underlying tissue. Both patients had satisfactory outcomes without complications.

CONCLUSIONS

This method is easy and safe and it facilitates the cranioplasty, reducing the potential complications, including intracranial haematoma, effusions and infection, and thereby improving the patient outcome.

Brain tumour stem cells and neural stem cells: still explored by the same approach?

Brain tumour stem cells (BTSCs) are chiefly responsible for the in vivo long-term growth and recurrence of malignant gliomas and may be a potential treatment target. They resemble neural stem cells (NSCs), so their self-renewal and differentiation are currently investigated by the same methods used to study NSCs. There are, however, essential differences between these cell types: in many cases the marker expression pattern of BTSCs does not match the CD133(+)/NSE(-)/FAP(-) pattern of NSCs; BTSC tumourigenicity is independent of marker expression; and while attachment, serum-containing medium and withdrawal of mitogens (epidermal growth factor [EGF] and basic fibroblast growth factor [bFGF]) are essential to induce NSCs to differentiate, they do not affect BTSC tumourigenicity. Evidence implies that research on the renewal and differentiation of BTSCs should be orientated towards tumourigenicity and is essentially a pharmaceutical problem. Such an approach may contribute to the development of an accurate definition of BTSCs and to the search for selective differentiation-inducing drugs for BTSCs.

The construction of a novel kind of non-viral gene delivery vector based on protein as core backbone

BACKGROUND AND OBJECTIVES

A novel kind of non-viral gene delivery vector based on transferrin (Tf) as the core component was constructed with high transfection efficiency and low toxicity.

MATERIALS AND METHODS

The synthesis vector of Tf-PEI600 was confirmed by different physicochemical methods, including (1)H nuclear magnetic resonance, gel permeation chromatography, X-ray and thermogravimetric analysis. The cytotoxicity and gene delivery efficiency of the synthesized vector were verified by in vitro experiments.

RESULTS

The agarose gel electrophoresis assay indicated that the novel copolymer Tf-PEI600 could efficiently condense plasmid DNA and the condensed nanoparticles exhibited a spherical shape. As the weight ratio of Tf-PEI600 to DNA reached 15.0, the particle size (about 200 nm) and the zeta potential (about 20 mV) of the nanoparticles became optimal for gene delivery. The methylthiazolyl tetrazolium (MTT) assay showed the cytotoxicity of Tf-PEI600 to be similar to that of PEI600 and much lower than that of PEI25kDa. In gene-delivery experiments with COS-7 cells and HepG2 cells, the Tf-PEI600 showed about a 30- to 53-fold higher efficiency than PEI600 and nearly equal to that of PEI25kDa.

CONCLUSIONS

These data suggest that Tf-PEI600, with the advantages of low toxicity and high gene-delivery efficiency, might have great prospects in the practice of gene delivery. The core-shell structure of Tf-PEI600 also provided a novel strategy for the construction of non-viral gene delivery vectors.

Expression changes of mitogen-activated protein kinase phosphatase-1 (MKP-1) in myocardium of streptozotocin-induced diabetic rats

MAP Kinase Phosphatase-1 (MKP-1) is a dual specific phosphatase selective for MAP kinases, and was believed to implicate in the development of cardiac hypertrophy. However, whether MKP-1 is involved in the pathogenesis of diabetic cardiomyopathy is still unknown. We employed streptozotocin (STZ)-induced diabetic Sprague-Dawley rats to study the alteration of the MKP-1 expressions in the left ventricular myocardium in diabetic and normal groups by immunohistochemistry and real-time quantitative reverse transcription-polymerase chain reaction. The weight, blood sugar and urine sugar were measured before and after model induction in both control and diabetic groups. Changes of heart ultrastructure were analyzed by using transmission electron microscopy. The data of weight, blood sugar and urine sugar indicated no significant difference between the two groups before animal model induction. Eight weeks after the induction of diabetes, the differences between the control and the diabetic groups in weight, blood sugar and urine sugar were significant ( P<0.01). When compared with control, diabetic myocardium ultrastructural changes included myofibrillar disarrangements, mitochondria disruption, and increase in nuclear membrane invaginations. A significant decrease of MKP-1 expression was observed in the diabetic rats' myocardium ( P<0.01). Our study provides experimental evidences that hyperglycemia could damage myocardial ultrastructure. Moreover, we provided first evidence that down-regulation of cardioprotective peptide MKP-1, the MAPK pathway negative regulator, in myocardium of streptozotocin-induced diabetic rats, which may contribute to the deterioration of cardiac function and lead to diabetic cardiomyopathy.

Many-body dipole-dipole interactions between excited Rb atoms probed by wave packets and parametric four-wave mixing

Dipole-dipole interactions between excited Rb atoms at long range (approximately 300a0-2150a0) have been observed with molecular wave packets and a coherent nonlinear optical process. Fourier analysis of the parametric four-wave mixing (PFWM) signal wave intensity produced in femtosecond pump-probe experiments demonstrates the appearance of sidebands associated with the Rb 7s-5d(5/2) quantum beating frequency of approximately 18.3 THz. Calculations show that the observed sideband splittings and Fourier domain profiles result from multiple atom, dipole-dipole interactions, and ensembles comprising five or fewer Rb (7s, 6p) atoms account for virtually all of the data.

Two novel monoclonal antibodies to VWFA3 inhibit VWF-collagen and VWF-platelet interactions

BACKGROUND

The interaction of collagen-von Willebrand factor (VWF)-GPIb is essential for platelet adhesion, especially under high shear conditions. VWF, which acts as a bridge between platelets and exposed subendothelium, interacts with collagen through its A3 domain, which is a new target for the antithrombotic agent.

OBJECTIVE

To develop functional blockers that specifically inhibit VWF-dependent adhesion of platelets to collagen under high shear stress.

METHODS

To develop murine antihuman VWF A3 monoclonal antibodies (mAbs) by standard hybridoma technology, and characterize their abilities to block interactions between VWF A3 and collagen as well as platelet function.

RESULTS

Thirty anti-VWF-A3 mAbs were obtained. Among them, two mAbs, designated as SZ-123 and SZ-125, were found to inhibit VWF-collagen type III interaction. SZ-123 and SZ-125 inhibited the binding of purified human VWF (1.5 or 3 mug mL(-1)) to human placenta collagen type III (IC(50) = 0.07 +/- 0.02 and 0.15 +/- 0.03 mug mL(-1), respectively) or to calf skin collagen type III (IC(50) = 0.48 +/- 0.06 and 0.51 +/- 0.07 mug mL(-1), respectively) coated on plates. Under flow shear condition (1000 s(-1)), SZ-123 and SZ-125 inhibited platelet adhesion on human placenta collagen- or calf skin collagen-coated surfaces. Both mAbs also inhibited platelet aggregation induced by ristocetin, botrocetin or bovine plasma.

CONCLUSIONS

SZ-123 and SZ-125 inhibited VWF-collagen and VWF-platelet interactions.

Nullifying drug-induced sensitization: behavioral and electrophysiological evaluations of dopaminergic and serotonergic ligands in methamphetamine-sensitized rats

Repeated exposure to methamphetamine produces a persistent enhancement of the acute motor effects of the drug, commonly referred to as behavioral sensitization. Behavioral sensitization involves monoaminergic projections to several forebrain nuclei. We recently revealed that the ventral pallidum (VP) may also be involved. In this study, we sought to establish if treatments with antagonists or partial agonists to monoaminergic receptors could "reverse" methamphetamine-induced behavioral and VP neuronal sensitization. Behavioral sensitization was obtained in rats with five once-daily s.c. injections of 2.5mg/kg methamphetamine, an effect that persisted for at least 60 days. After the development of sensitization, 15 once-daily treatments of mirtazapine (a 5-HT(2/3), alpha(2) and H(1) antagonist), SKF38393 (D(1) partial agonist) or SCH23390 (dopamine D(1) antagonist) nullified indices of motor sensitization as assessed by measuring the motoric response to an acute methamphetamine challenge 30 days after the fifth repeated methamphetamine treatment. VP neurons recorded in vivo from methamphetamine-sensitized rats at the 30-day withdrawal time also showed a robust downward shift in the excitatory responses observed to an acute i.v. methamphetamine challenge in non-sensitized rats. This decreased excitatory effect was reversed by mirtazapine, but not by other antagonists that were tested. These data suggest a potential therapeutic benefit for mirtazapine in the treatment of methamphetamine addiction, and point to a possible role for the VP in the sensitization process to methamphetamine.

Modified Bilston nonlinear viscoelastic model for finite element head injury studies

This paper proposes a modified nonlinear viscoelastic Bilston model (Bilston et al., 2001, Biorheol., 38, pp. 335-345). for the modeling of brain tissue constitutive properties. The modified model can be readily implemented in a commercial explicit finite element (FE) code, PamCrash. Critical parameters of the model have been determined through a series of rheological tests on porcine brain tissue samples and the time-temperature superposition (TTS) principle has been used to extend the frequency to a high region. Simulations by using PamCrash are compared with the test results. Through the use of the TTS principle, the mechanical and rheological behavior at high frequencies up to 10(4) rads may be obtained. This is important because the properties of the brain tissue at high frequencies and impact rates are especially relevant to studies of traumatic head injury. The averaged dynamic modulus ranges from 130 Pa to 1500 Pa and loss modulus ranges from 35 Pa to 800 Pa in the frequency regime studied (0.01 rads to 3700 rads). The errors between theoretical predictions and averaged relaxation test results are within 20% for strains up to 20%. The FEM simulation results are in good agreement with experimental results. The proposed model will be especially useful for application to FE analysis of the head under impact loads. More realistic analysis of head injury can be carried out by incorporating the nonlinear viscoelastic constitutive law for brain tissue into a commercial FE code.

An adaptive incremental LBG for vector quantization

This study presents a new vector quantization method that generates codewords incrementally. New codewords are inserted in regions of the input vector space where the distortion error is highest until the desired number of codewords (or a distortion error threshold) is achieved. Adoption of the adaptive distance function greatly increases the proposed method's performance. During the incremental process, a removal-insertion technique is used to fine-tune the codebook to make the proposed method independent of initial conditions. The proposed method works better than some recently published efficient algorithms such as Enhanced LBG (Patane, & Russo, 2001) for traditional tasks: with fixed number of codewords, to find a suitable codebook to minimize distortion error. The proposed method can also be used for new tasks that are insoluble using traditional methods: with fixed distortion error, to minimize the number of codewords and find a suitable codebook. Experiments for some image compression problems indicate that the proposed method works well.

[Effects of angiotensin II on the 3H-TdR incorporation and synthesis of collagen in cultured bovine trabecular meshwork cells]

OBJECTIVE

To investigate the effects of angiotensin II (Ang II) on the cell proliferation and collagen synthesis of bovine trabecular meshwork (TM) cells in vitro. It may probe into the mechanism of primary open-angle glaucoma(POAG).

METHODS

(1) The bovine trabecular meshwork cells were cultured and identified by immunohistochemistry method(neuronal specific enolas, NSE, factor related antigan). The growing characteristics and morphological feature of cultured primary and passaged cells were observed by invered microscope and eletron-microscope; (2) Ang II(1 x 10(-7) mol.L-1 and 1 x 10(-8) mol.L-1) and angiotensin receptor type I (AT1) antagonist (losartan) were incubated with cultured TM cells. The cellular proliferation was measured by 3H-thymidine(3H-TdR) incorporation assay and collagen synthesis was indirectly professed though detects the hydroxyproline of medium with chemistry methods.

RESULTS

The cells of bovine trabecular meshwork were cultured successfully. Most of them were epithelia type. Ang II increased the TM cells uptake of 3H-TdR and inhibited by losartan partially. Meanwhile the hydroxyproline of medium was increased correspondingly.

CONCLUSION

Establishing the method of culturing bovine trabecular meshwork cells is an important method for researching the characteristics of TM cells. Ang II can induce the cell proliferation of bovine TM cells and increase the synthesis of collagen in vitro. The AT1 antagonist may inhibit this cell proliferation effect.

[Complex segregation analysis of systemic lupus erythematosus]

OBJECTIVE

To explore the genetic model of systemic lupus erythematosus(SLE).

METHODS

Complex segregation analysis was performed by using statistical analysis for genetic epidemiology-REGTL(SAGE-REGTL). The genetic model and gene frequency were estimated. 300 pedigrees with SLE were collected from 300 patients as probands.

RESULTS

The complex segregation analysis found the genetic model of SLE to be additive,the gene frequency 0.336. The authors believe the possibility of some different modes coexisting under different circumstances. The genetic effect on young man is stronger than that on old one.

CONCLUSION

This study suggests that the genetic mode of SLE could be the major gene trait, and additive mode is the best fitted one.

[Relationship of vitamin D receptor polymorphism with breast cancer]

OBJECTIVE

To detect the association between vitamin D receptor polymorphism and breast cancer.

METHODS

Polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) method was used. Two restriction fragment length polymorphisms in the 3'region of vitamin D receptor (VDR) gene, Taq I and Apa I, were tested for association with breast cancer risk in 86 females with breast cancer and 134 healthy female controls.

RESULTS

Allele frequencies of the 3'Taq I polymorphism showed a significant association (P=0.0004, OR:5.39,CI:1.81-17.20). The further study of genotype found the association of Tt, tt with breast cancer. The haplotype analysis of Apa I and Taq I showed a linkage disequilibrium between t-allele and A-allele. The frequency of tA haplotype was higher in breast cancer patients than in controls (P=0.001), indicating that tA haplotype is associated with breast cancer. The alleles and haplotype of the two loci had not any difference among the clinical subgroups.

CONCLUSION

There is association between vitamin D receptor polymorphism and breast cancer.