Comparison of the effects of EM-652 (SCH57068), tamoxifen, toremifene, droloxifene, idoxifene, GW-5638 and raloxifene on the growth of human ZR-75-1 breast tumors in nude mice

EM-652 exerts pure antiestrogenic activity in the mammary gland and endometrium, while tamoxifen, the antiestrogen most widely used for the treatment of breast cancer, exerts mixed antiestrogenic-estrogenic activity in these tissues. Our objective was to compare the agonistic and antagonistic effects of EM-652 with tamoxifen and 5 other antiestrogens on the growth of ZR-75-1 human breast xenografts in ovariectomized nude mice. During the 23 weeks of treatment at a daily oral dose of 50 microg, EM-652 was the only compound that decreased tumor size relative to pretreatment values, whereas the 6 other antiestrogens only decreased to various extents the progression rate stimulated by estrone. Under estrone stimulation, all groups of animals had more than 60% of their tumors in the progression category except for the EM-652-treated group, where only 7% of the tumors progressed. In the absence of estrone stimulation, progression was seen in 60%, 33%, 21% and 12% of tumors in the tamoxifen-, idoxifene-, toremifene- and raloxifene-treated groups, respectively, while only 4% of tumors progressed in the EM-652-treated group. The agonistic and antagonistic actions of each antiestrogen were also measured on endometrial epithelial cell thickness. Our present findings indicate that EM-652, in addition to being the most potent antiestrogen on human breast tumor growth, has no agonistic effect in breast and endometrial tissues. Since previous data have shown benefits of EM-652 on bone density and lipid profile, this compound could be an ideal candidate for chemoprevention of breast and uterine cancers, while protecting against osteoporosis and cardiovascular disease.     

Preclinical Development of Eniluracil: Enhancing the Therapeutic Index and Dosing Convenience of 5-Fluorouracil

Eniluracil (5-ethynyluracil, GW 776, 776C85) isbeing developed as a novel modulator of 5-fluorouracil (5-FU) forthe treatment of cancer. Eniluracil is an effective mechanism-based inactivator of dihydropyrimidine dehydrogenase (DPD), thefirst enzyme in the catabolic pathway of 5-FU. By temporarilyeliminating this prevalent enzyme, eniluracil providespredictable dosing of 5-FU and enables oral administration of5-FU to replace intravenous bolus and continuously infuseddosing. New DPD is synthesized with a half-life of 2.6 days. Italso eliminates the formation of problematic 5-FU catabolites.Most importantly, in laboratory animals, eniluracil increases thetherapeutic index and absolute efficacy of 5-FU. Accompanyingreports in this journal indicate that eniluracil has promisingclinical potential.     

Lack of accuracy of continuous glucose sensors in healthy, nondiabetic children: results of the Diabetes Research in Children Network (DirecNet) accuracy study

OBJECTIVE: The workup of hypoglycemia requires frequent glucose sampling. We designed these studies to determine if the Continuous Glucose Monitoring System (CGMS) and the GlucoWatch G2 Biographer (GW2B) are sufficiently accurate to use in nondiabetic children.Study design Fifteen healthy children (aged 9-17 years, 11 boys) wore a GW2B and a CGMS during a 24-hour period, and reference serum glucose was measured hourly during the day and half-hourly overnight. RESULTS: Compared with the reference glucose, the median absolute difference in concentrations measured by the GW2B (487 pairs) was 13 mg/dL, and the difference measured by the CGMS was 17 mg/dL (668 pairs), with 30% and 42% of values using the GW2B and CGMS, respectively, deviating >20 mg/dL from the reference value. The GW2B reported values <60 mg/dL in 73% of subjects, the CGMS in 60% of subjects. In none of these episodes was serum glucose truly low. Spurious high glucose concentrations also were observed with the sensors. The mean reference glucose was lowest at 5 am (89 mg/dL) and highest at 11:30 pm (106 mg/dL) during the 24-hour period. CONCLUSIONS: Neither the CGMS nor the GW2B is accurate enough to establish population standards of the glycemic profile of healthy children and cannot be recommended in the workup of hypoglycemia in nondiabetic youth.     

GW843682X对鼻咽癌细胞中PLK1和p53表达的影响

[目的]研究Polo样激酶（PLK）抑制剂GW843682X对鼻咽癌5-8F细胞中PLK1和p53表达水平的影响。[方法]用不同浓度的GW843682X处理鼻咽癌5-8F细胞,在不同时间点倒置显微镜下观察细胞形态,RT-PCR及Western blot分别检测PLK1和p53的mRNA和蛋白表达水平的变化。[结果]GW843682X能够显著抑制5-8F细胞的增殖,呈剂量和时间依赖性。RT-PCR结果表明GW843682X可下调PLK1和p53的mRNA表达水平。Western blot结果显示GW843682X降低PLK1和p53的蛋白表达水平。[结论]GW843682X抑制鼻咽癌5-8F细胞中PLK1和p53的表达。     

Lack of effect of chronic pre-treatment with the FAAH inhibitor URB597 on inflammatory pain behaviour: evidence for plastic changes in the endocannabinoid system

BACKGROUND AND PURPOSE

Elevating levels of endocannabinoids with inhibitors of fatty acid amide hydrolase (FAAH) is a major focus of pain research, purported to be a safer approach devoid of cannabinoid receptor-mediated side effects. Here, we have determined the effects of sustained pharmacological inhibition of FAAH on inflammatory pain behaviour and if pharmacological inhibition of FAAH was as effective as genetic deletion of FAAH on pain behaviour.

EXPERIMENTAL APPROACH

Effects of pre-treatment with a single dose, versus 4 day repeated dosing with the selective FAAH inhibitor, URB597 (i.p. 0.3 mg·kg⁻¹), on carrageenan-induced inflammatory pain behaviour and spinal pro-inflammatory gene induction were determined in rats. Effects of pain induction and of the drug treatments on levels of arachidonoyl ethanolamide (AEA), palmitoyl ethanolamide (PEA) and oleolyl ethanolamide (OEA) in the spinal cord were determined.

KEY RESULTS

Single, but not repeated, URB597 treatment significantly attenuated the development of inflammatory hyperalgesia (P < 0.001, vs. vehicle-treated animals). Neither mode of URB597 treatment altered levels of AEA, PEA and OEA in the hind paw, or carrageenan-induced paw oedema. Single URB597 treatment produced larger increases in AEA, PEA and OEA in the spinal cord, compared with those after repeated administration. Single and repeated URB597 treatment decreased levels of immunoreactive N-acylphosphatidylethanolamine phospholipase D (NAPE-PLD) in the spinal cord and attenuated carrageenan-induced spinal pro-inflammatory gene induction.

CONCLUSION AND IMPLICATIONS

Changes in the endocannabinoid system may contribute to the loss of analgesic effects following repeated administration of low dose URB597 in this model of inflammatory pain.     

Impaired myelination of the human hippocampal formation in Down syndrome

Myelination is considered as one of the last steps of neuronal development and is essential to the physiologically matured function of afferent and efferent pathways. In the present study, myelin formation was examined in the human fetal, postnatal and adult hippocampal formation in Down syndrome and in age-matched controls with immunohistochemistry detecting a protein component of the myelin sheath, the myelin basic protein synthesized by oligodendroglial cells. Myelination is mainly a postnatal event in the hippocampal formation of both healthy controls and in patients with Down syndrome. In patients with Down syndrome the sequence of myelination of the hippocampal formation followed a similar developmental pattern to that in controls. However, myelin formation was generally delayed in Down syndrome compared to age-matched controls. In addition, in the hilus of the dentate gyrus a decreased density of myelinated axons was detected from the start of myelination until adulthood. The majority of local axons (mossy fibers) are not myelinated in the hilar region and myelinated fibers arriving in the hilus come mainly from the subcortical septal nuclei. Since intact septo-hippocampal connections are necessary for memory formation, we hypothesize that decreased myelination in the hilus may contribute to the mental retardation of Down syndrome patients.     

Analgesic potential of intrathecal farnesyl thiosalicylic acid and GW 5074 in vincristine-induced neuropathic pain in rats

Ras and c-Raf constitute an important part of mitogen-activated protein (MAP) kinase family as Ras/Raf/MEK/ERK2 signaling cascade and the role of MAP kinases has been well defined in neuropathic pain. The present study investigates the analgesic potential of farnesyl thiosalicylic acid, a novel Ras inhibitor, and GW 5074, a selective c-Raf1 inhibitor, in vincristine-induced neuropathic pain. Peripheral neuropathy was induced in rats by administering vincristine (50 μg/kg i.p.) for 10 consecutive days. Pain development was assessed on 14th day in terms of cold allodynia; mechanical hyperalgesia and mechanical allodynia by performing acetone test, pin-prick and von frey tests, respectively. Farnesyl thiosalicylic acid and GW 5074 were injected intrathecally on 14th day following vincristine administration. Administration of vincristine produced significant neuropathic pain manifestations in terms of cold and mechanical allodynia, and mechanical hyperalgesia. Single intrathecal administration of farnesyl thiosalicylic acid (5 and 10 μg) as well as GW 5074 (2 and 4 μg) significantly attenuated vincristine-induced hyperalgesia and allodynia. The analgesic effects of farnesyl thiosalicylic acid and GW 5074 in vincristine model suggests that pharmacological inhibition of Ras and c-Raf-1 signalling may be potentially useful for managing neuropathic pain.     

Molecular inhibition of prostaglandin E2 with GW627368X: Therapeutic potential and preclinical safety assessment in mouse sarcoma model

Prostaglandin E2, the major COX-2 product, acts via 4 functionally distinct prostanoid receptors, EP(1–4). PGE-2, through its receptors, feeds back to positively increase COX-2 expression augmenting its own synthesis thereby driving angiogenesis, while suppressing apoptosis and innate immunity. In addition to the well characterized PGE2/EP4/cAMP/PKA/CREB, EP4 activation increases GSK3 phosphorylation via PI3K and Akt consequently reducing β-catenin phosphorylation. EP4 induces angiogenesis by enhancing VEGF production via ERK activation. These effects of EP4 are asserted either directly or via EGFR transactivation depending on the type of cancer. In view of the safety concerns regarding long term use of COX-2 inhibitors and to find more effective alternatives, we evaluated the potential of EP4 prostanoid receptor as a target for treating cancer progression using a highly selective EP4 antagonist, 4-(4,9-diethoxy-1,3-dihydro-1-oxo-2H-benz[f]isoindol-2-yl)-N-(phenylsulfonyl)-benzeneacetamide. Oral administration of GW627368X showed significant tumor regression characterized by tumor reduction and induction of apoptosis. Reduction in prostaglandin E2 synthesis also led to reduced level of VEGF in plasma. Regulation of multiple pathways downstream of EP4 was evident by down regulation of COX-2, p-Akt, p-MAPK and p-EGFR. Considering wide distribution of the EP4 prostanoid receptor in major organs and the array of physiological processes it contributes to, the safety profile of the drug was analyzed. No major organ toxicity, immunosupression, behavioral change or change in blood parameters attributable to the drug was observed. The results assert the significance of EP4 prostanoid receptor as a therapeutic target as well as the safety of EP4 blockade by GW627368X.