In vivo C6 glioma models: an update and a guide toward a more effective preclinical evaluation of potential anti-glioblastoma drugs

Glioblastoma multiform (GBM) is the most common primary brain tumor with a poor prognosis and few therapeutic choices. In vivo, tumor models are useful for enhancing knowledge of underlying GBM pathology and developing more effective therapies/agents at the preclinical level, as they recapitulate human brain tumors. The C6 glioma cell line has been one of the most widely used cell lines in neuro-oncology research as they produce tumors that share the most similarities with human GBM regarding genetic, invasion, and expansion profiles and characteristics. This review provides an overview of the distinctive features and the different animal models produced by the C6 cell line. We also highlight specific applications of various C6 in vivo models according to the purpose of the study and offer some technical notes for more convenient/repeatable modeling. This work also includes novel findings discovered in our laboratory, which would further enhance the feasibility of the model in preclinical GBM investigations.

CLEC19A overexpression inhibits tumor cell proliferation/migration and promotes apoptosis concomitant suppression of PI3K/AKT/NF-κB signaling pathway in glioblastoma multiforme

BACKGROUND

GBM is the most frequent malignant primary brain tumor in humans. The CLEC19A is a member of the C-type lectin family, which has a high expression in brain tissue. Herein, we sought to carry out an in-depth analysis to pinpoint the role of CLEC19A expression in GBM.

METHODS

To determine the localization of CLEC19A, this protein was detected using Western blot, Immunocytochemistry/Immunofluorescence, and confocal microscopy imaging. CLEC19A expression in glioma cells and tissues was evaluated by qRT-PCR. Cell viability, proliferation, migration, and apoptosis were examined through MTT assay, CFSE assay, colony formation, wound healing assay, transwell test, and flow cytometry respectively after CLEC19A overexpression. The effect of CLEC19A overexpression on the PI3K/AKT/NF-κB signaling pathway was investigated using Western blot. An in vivo experiment substantiated the in vitro results using the glioblastoma rat models.

RESULTS

Our in-silico analysis using TCGA data and measuring CLEC19A expression level by qRT-PCR determined significantly lower expression of CLEC19A in human glioma tissues compared to healthy brain tissues. By employment of ICC/IF, confocal microscopy imaging, and Western blot we could show that CLEC19A is plausibly a secreted protein. Results obtained from several in vitro readouts showed that CLEC19A overexpression in U87 and C6 glioma cell lines is associated with the inhibition of cell proliferation, viability, and migration. Further, qRT-PCR and Western blot analysis showed CLEC19A overexpression could reduce the expression levels of PI3K, VEGFα, MMP2, and NF-κB and increase PTEN, TIMP3, RECK, and PDCD4 expression levels in glioma cell lines. Furthermore, flow cytometry results revealed that CLEC19A overexpression was associated with significant cell cycle arrest and promotion of apoptosis in glioma cell lines. Interestingly, using a glioma rat model we could substantiate that CLEC19A overexpression suppresses glioma tumor growth.

CONCLUSIONS

To our knowledge, this is the first report providing in-silico, molecular, cellular, and in vivo evidences on the role of CLEC19A as a putative tumor suppressor gene in GBM. These results enhance our understanding of the role of CLEC19A in glioma and warrant further exploration of CLEC19A as a potential therapeutic target for GBM.

Synthetic miR-21 decoy circularized by tRNA splicing mechanism inhibited tumorigenesis in glioblastoma in vitro and in vivo models

Glioblastoma multiforme (GBM) is the deadliest primary central nervous system tumor. miRNAs (miRs), a class of non-coding RNAs, are considered pivotal post-transcriptional regulators of cell signaling pathways. miR-21 is a reliable oncogene that promotes tumorigenesis of cancer cells. We first performed an in silico analysis on 10 microarray datasets retrieved from TCGA and GEO databases to elucidate top differentially expressed miRs. Furthermore, we generated a circular miR-21 decoy, CM21D, using the tRNA-splicing mechanism in GBM cell models, U87 and C6. The inhibitory efficacy of CM21D with that of a linear form, LM21D, was compared under in vitro conditions and an intracranial C6 rat glioblastoma model. miR-21 significantly overexpressed in GBM samples and confirmed in GBM cell models using qRT-PCR. CM21D was more efficient than LM21D at inducing apoptosis, inhibiting cell proliferation and migration, and interrupting the cell cycle by restoring the expression of miR-21 target genes at RNA and protein levels. Moreover, CM21D suppressed tumor growth more effectively than LM21D in the C6-rat GBM model (p < 0.001). Our findings validate miR-21 as a promising therapeutic target for GBM. The introduced CM21D by sponging miR-21 reduced tumorigenesis of GBM and can be considered a potential RNA-base therapy to inhibit cancers.

The role of VEGF in cancer-induced angiogenesis and research progress of drugs targeting VEGF

Angiogenesis is a double-edged sword; it is a mechanism that defines the boundary between health and disease. In spite of its central role in physiological homeostasis, it provides the oxygen and nutrition needed by tumor cells to proceed from dormancy if pro-angiogenic factors tip the balance in favor of tumor angiogenesis. Among pro-angiogenic factors, vascular endothelial growth factor (VEGF) is a prominent target in therapeutic methods due to its strategic involvement in the formation of anomalous tumor vasculature. In addition, VEGF exhibits immune-regulatory properties which suppress immune cell antitumor activity. VEGF signaling through its receptors is an integral part of tumoral angiogenic approaches. A wide variety of medicines have been designed to target the ligands and receptors of this pro-angiogenic superfamily. Herein, we summarize the direct and indirect molecular mechanisms of VEGF to demonstrate its versatile role in the context of cancer angiogenesis and current transformative VEGF-targeted strategies interfering with tumor growth.

Molecular Pharmacology and Novel Potential Therapeutic Applications of Fingolimod

Fingolimod is a well-tolerated, highly effective disease-modifying therapy successfully utilized in the management of multiple sclerosis. The active metabolite, fingolimod-phosphate, acts on sphingosine-1-phosphate receptors (S1PRs) to bring about an array of pharmacological effects. While being initially recognized as a novel agent that can profoundly reduce T-cell numbers in circulation and the CNS, thereby suppressing inflammation and MS, there is now rapidly increasing knowledge on its previously unrecognized molecular and potential therapeutic effects in diverse pathological conditions. In addition to exerting inhibitory effects on sphingolipid pathway enzymes, fingolimod also inhibits histone deacetylases, transient receptor potential cation channel subfamily M member 7 (TRMP7), cytosolic phospholipase A2α (cPLA2α), reduces lysophosphatidic acid (LPA) plasma levels, and activates protein phosphatase 2A (PP2A). Furthermore, fingolimod induces apoptosis, autophagy, cell cycle arrest, epigenetic regulations, macrophages M1/M2 shift and enhances BDNF expression. According to recent evidence, fingolimod modulates a range of other molecular pathways deeply rooted in disease initiation or progression. Experimental reports have firmly associated the drug with potentially beneficial therapeutic effects in immunomodulatory diseases, CNS injuries, and diseases including Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy, and even cancer. Attractive pharmacological effects, relative safety, favorable pharmacokinetics, and positive experimental data have collectively led to its testing in clinical trials. Based on the recent reports, fingolimod may soon find its way as an adjunct therapy in various disparate pathological conditions. This review summarizes the up-to-date knowledge about molecular pharmacology and potential therapeutic uses of fingolimod.

Albendazole loaded albumin nanoparticles for ovarian cancer therapy

Albendazole (ABZ), a well-established antiparasitic drug, has been shown to suppress tumor growth in a number of preclinical models of cancer. However, the low solubility of ABZ limits its use as a systemic anticancer agent. To enable systemic administration, we have formulated ABZ into albumin nanoparticles with a size range of 200–300 nm, which were cross-linked with glutaraldehyde to stabilize the nanoparticles and to introduce pH-responsive features. Drug release studies demonstrated that about 20% of ABZ was released at neutral pH within a week in comparison to 70% at slightly acidic condition (pH 5). Cellular uptake studies using ovarian cancer cells indicated that nanoparticles were internalized efficiently within 1 h of incubation. Further, cell proliferation results demonstrated that albumin nanoparticles alone showed no cytotoxicity to both normal and cancer cells. In contrast, the drug-loaded nanoparticles exhibited cellular toxicity and high killing efficacy to cancer cells compared to normal cells. Collectively, our results suggest that these albumin nanoparticles may hold great potentials as ABZ carriers for cancer therapy.

Tetracyclines: drugs with huge therapeutic potential

Tetracyclines are an amazing class of chemical agents with multiple therapeutic potential. Structural modification of the original natural tetracyclines led to the synthesis and development of doxycycline and minocycline, compounds with higher lipophilicity, better oral pharmacokinetics and higher potency. Due to diverse pharmacological properties, these drugs are now under extensive investigation for use in the treatment of various disparate diseases. In recent years, several studies have conclusively reported anti-inflammatory, immune-modulating and neuroprotective effects of these compounds. There are currently over 200 ongoing clinical trials on tetracyclines. These studies extend over a wide range of diseases including dermatological diseases, behavior and mental disorders, immune system disorders, cardiovascular diseases, and cancer. In this review we will discuss the chemistry and pharmacology of these agents, and describe how their inhibitory effect on matrix metalloproteinase and on pro-inflammatory cytokines has kindled renewed interest in them. Based on the reports from pre-clinical and clinical trials, the therapeutic potential and application of tetracyclines may well be redefined and extensively extended.

The critical role of vascular endothelial growth factor in tumor angiogenesis

Angiogenesis is the formation of new blood vessels from the pre-existing vasculature. Besides its role in normal physiology, angiogenesis is significantly involved in many pathological conditions, including inflammation, cardiovascular diseases and cancer. Numerous studies have been undertaken in the area of tumor angiogenesis. It is known that pathological angiogenesis is necessary for tumors to proceed from avascular, dormant stage to vascular, sprouting stage and also contributes to their later invasion and metastasis. Playing a central role in tumor angiogenesis, vascular endothelial growth factor is considered as a key target in therapeutic approaches. This article aims to review the critical role of VEGF in tumor angiogenesis and the importance of VEGF-targeted strategies in cancer treatment.

Inhibition of cell proliferation, vascular endothelial growth factor and tumor growth by albendazole

Vascular endothelial growth factor (VEGF) is the key molecule mediating tumor growth and malignant ascites formation. We recently reported that, in an end stage OVCAR-3 xenograft model, albendazole (ABZ) suppresses ascites formation, but not tumor growth. Hence, in the present study, we assessed the effect of ABZ on in vitro OVCAR-3 cell proliferation plus in vivo tumor growth, however, initiating ABZ treatment at mid stage (3 weeks post cell inoculation) rather than end stage disease. Here, ABZ treatment led to potent inhibition of cell proliferation, VEGF suppression, complete inhibition of ascites formation and most strikingly arrest of tumor growth.

Albendazole: a potent inhibitor of vascular endothelial growth factor and malignant ascites formation in OVCAR-3 tumor-bearing nude mice

PURPOSE

Angiogenesis and vessel hyperpermeability are the two factors leading to the formation of ascites. Vascular endothelial growth factor (VEGF) plays a pivotal role in malignant ascites formation. We have recently shown that albendazole inhibits peritoneal growth of human colorectal cancer cells (HT-29). The present study was designed to find out if albendazole can suppress ascites formation in ascites-producing peritoneal carcinomatosis.

EXPERIMENTAL DESIGN

Female nude mice bearing peritoneal tumors of human ovarian cancer cells (OVCAR-3) were treated with albendazole. Following i.p. inoculation and ascites development, mice were given i.p. albendazole (150 mg/kg) or the vehicle x 3 weekly for 4 weeks.

RESULTS

Whereas vehicle-treated mice developed overt ascites requiring repeated aspiration, ascites formation in the albendazole-treated mice was markedly suppressed. As a result of this, 7 of 10 mice from the control group had to be euthanized before the course of treatment was over. Suppressed ascites production and reduced tumor vascularity observed was a result of dramatic reduction in tumor VEGF production as revealed by profoundly lower VEGF ascites fluid and plasma levels. In vitro, incubation of SKOV-3 cells with various concentrations of albendazole led to significant dose-dependent inhibition of VEGF secretion. Examination of floating tumor cells collected from the peritoneal wash revealed profound down-regulation of VEGF mRNA in albendazole-treated mice.

CONCLUSIONS

These findings suggest for the first time that in nude mice bearing OVCAR-3 peritoneal tumors, by inhibiting VEGF production, albendazole abolishes tumor angiogenesis and ascites formation.

1,25-Dihydroxyvitamin D3 in lipiodol for the treatment of hepatocellular carcinoma: cellular, animal and clinical studies

1,25-Dihydroxyvitamin D(3) (1,25-(OH)(2) D(3)) is a potent regulator of cell growth and differentiation, with recent evidence showing inhibition of tumor invasion, angiogenesis and tumor cell death. The growth-inhibitory properties of 1,25-(OH)(2) D(3) could be harnessed in the treatment of patients with cancer if the development of systemic hypercalcemia is avoided. Hepatocellular cancer (HCC) presents a setting where the tumor is accessible for treatment through the hepatic artery and also where the tumor is highly lipiodol avid. On this basis, we hypothesised that, 1,25-(OH)(2) D(3) dissolved in lipiodol and administered through the hepatic artery may prove to be a rational approach to the use of the drug in the treatment of HCCs. In brief, 6 years of work with 1,25-(OH)(2) D(3) at cellular, animal and clinical level has provided us with plenty of support for this hypothesis. Sensitivity of HCCs in cell culture to 1,25-(OH)(2) D(3), growth retardation of human HCC xenografts in nude mice, uptake and retention of 1,25-(OH)(2) D(3)-lipiodol by liver tumors in cell culture and animals, escalation of the 1,25-(OH)(2) D(3) dose by 100x without the development of hypercalcemia in both liver tumor bearing rats and in patients with HCC are some of the evidence that will be discussed in this paper.

Hepatic intra-arterial injection of 1,25-dihydroxyvitamin D3 in lipiodol: Pilot study in patients with hepatocellular carcinoma

1,25-dihydroxycholecalciferol [1,25-(OH)2 D3] has been shown to have antiproliferative effects in a wide variety of cancer cell lines. In vivo studies, although often limited by the development of hypercalcemia, have also shown the potential usefulness of 1,25-(OH)2 D3 in inhibiting tumor growth. The potential usefulness of the drug has been hampered by the development of hypercalcemia. This pilot clinical study was designed to evaluate the preclinical results that have shown, locoregional administration of 1,25-(OH)2 D3 in lipiodol can prevent the development of hypercalcemia. Eight patients with refractory HCC were given a single intrahepatic arterial dose (50, 75 or 100 microg) of 1,25-(OH)2 D3 dissolved in 5 ml of lipiodol. Following this, for 4 weeks serum calcium, 1,25-(OH)2 D3, alpha-fetoprotein and a range of biochemical indices were monitored. While, in 3 patients the calcium levels exceeded the normal range, even at these extremely high doses, non of the patients developed grade 3 hypercalcemia. 1,25-(OH)2 D3 administration also led to transient stabilization of serum alpha-fetoprotein in these patients. The data obtained support the hypothesis that, in patients with HCC, locoregional delivery of 1,25-(OH)2 D3 in lipiodol can allow administration of supra-pharmacological doses of the drug without the development of hypercalcemia.

Hippocampal hyperexcitability facilitates amygdala kindling in rats

BACKGROUND & OBJECTIVES

The amygdala and hippocampus are recognized as the two important structures in the brain involved in the development and control of kindled seizures. The study on the precise interconnection between these two regions can provide important insights into the functional anatomy of complex partial seizures. In this study the effect of an experimentally increased excitability in hippocampal neurons, via hippocampal kindling, on the amygdala kindling rate was investigated in rats.

METHODS

Animals were divided into four groups. Tripolar electrodes were implanted in the amygdala and CA1 region of the dorsal hippocampus of animals of Groups 1, 3 and 4. In Group 2 animals, tripolar electrodes were only implanted in the amygdala. In Group 1, one week after surgery, the rats were kindled first from the hippocampus and the next day kindled by amygdala stimulation. In Groups 2 and 3, one week after surgery, rats were kindled from the amygdala. Group 4 animals had a recovery period of one week plus 32 days, which was the mean of the hippocampal kindling rate in Group 1, and then were kindled from the amygdala.

RESULTS

In Group 1, the amygdala kindling rate (n; number of days for which animals were stimulated before a stage 5 motor convulsion is triggered) and seizure stage at day n/2 were significantly facilitated and increased respectively. There was also a significant positive correlation between hippocampal and amygdala kindling rates.

INTERPRETATION & CONCLUSION

Results obtained show that an increase in hippocampal excitability can facilitate kindling from the amygdala. Thus, it is suggested that the hippocampus has an important role in the development and propagation of seizures from the amygdala.

Hepatic arterial and intravenous administration of 1,25-dihydroxyvitamin D3--evidence of a clinically significant hepatic first-pass effect

PURPOSE

We have previously shown that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] inhibits the proliferation of a number of human cancers, including colorectal and hepatocellular carcinoma, both of which affect the liver and are major causes of cancer death. However, the clinical use of 1,25(OH)2D3 and analogues has been restricted by the development of hypercalcaemia upon systemic administration. We hypothesized that a clinically significant hepatic first-pass effect may exist upon the administration of 1,25(OH)2D3 as a hepatic arterial infusion, and that such an effect may allow high levels of 1,25(OH)2D3 to be delivered to the liver whilst avoiding high systemic levels.

METHODS

To examine this hypothesis, two groups of Landrace pigs were given identical doses of 1,25(OH)2D3 as continuous infusions, one group systemically, the other as a hepatic arterial infusion. Serum levels of 1,25(OH)2D3, calcium, phosphate and a number of liver and kidney function tests were performed regularly.

RESULTS

Concentrations of 1,25(OH)2D3 and calcium remained normal in the hepatic arterial infusion animals, in contrast to the intravenous infusion animals which developed elevated levels of 1,25(OH)2D3 and hypercalcaemia. Hepatic arterial infusion of 1,25(OH)2D3 did not produce any adverse effects upon renal or hepatic function.

CONCLUSION

The present findings support the existence of a clinically significant hepatic first-pass effect when 1,25(OH)2D3 is administered as a continuous hepatic arterial infusion. Hepatic arterial infusion of 1,25(OH)2D3 has great potential in the treatment of hepatic cancers.

Pilot study of albendazole in patients with advanced malignancy. Effect on serum tumor markers/high incidence of neutropenia

Our preclinical studies have shown that the widely used antiparasitic drug albendazole has potent antiproliferative activity against colorectal cancer (CRC) and hepatocellular carcinoma (HCC). This trial was designed to evaluate albendazole in a small number of patients (n = 7) with either HCC or CRC and hepatic metastases refractory to other forms of therapy. Albendazole was given at 10 mg/kg/day orally in two divided doses for a period of 28 days. To follow the effect of treatment, tumor markers, carcinoembryonic antigen (CEA) or alpha-feto protein (AFP), were measured routinely in these patients. A range of hematological and biochemical indices were also serially measured to monitor bone marrow, kidney or liver toxicity. Albendazole therapy resulted in a decrease in CEA in 2 patients. In the remaining 5 with measurable tumor markers, serum CEA or AFP was stabilized in 3 patients, while in the other 2, after an initial stabilization (5-10 days), the markers began to increase. In the 7 patients completing the trial, albendazole was well tolerated and there were no significant changes in any hematological, kidney or liver function tests, but 3 patients were withdrawn for severe neutropenia which was probably contributory to the death of 1 patient. These data support our previous experimental results demonstrating that albendazole has antitumor effects.

1alpha,25-Dihydroxyvitamin D3 and its analogues, EB1089 and CB1093, profoundly inhibit the in vitro proliferation of the human hepatoblastoma cell line HepG2

BACKGROUND

1alpha,25-dihydroxyvitamin D3 (1,25[OH]2D3) has been shown to inhibit the proliferation of various cancer cells including colon, prostate, melanoma, osteosarcoma and breast cancer.

METHODS

The human hepatoma cell line (HepG2) was cultured with 1,25(OH)2D3 or one of two analogues EB1089 or CB1093 for various durations. Cellular proliferation was measured by uptake of [3H]thymidine, and cell numbers were determined by trypan blue exclusion counting.

RESULTS

1,25(OH)2D3, EB1089 and CB1093 all inhibited proliferation of HepG2 by up to 90% after 5 days of treatment, compared to the untreated controls. Decreased proliferation was associated with an approximately 50% reduction in cell numbers at concentrations of up to 10(-10) mol/L after 5 days of treatment with 1,25(OH)2D3. Cell proliferation rapidly recovered in cultures treated with lower concentrations of 1,25(OH)2D3 (10(-10) and 10(-11) mol/L) when 1,25(OH)2D3 was removed from the cultures by placing cells in serum containing medium without 1,25(OH)2D3. When HepG2 cells were treated with 10(-8) mol/L 1,25(OH)2D3 for 5 weeks, there was still significant inhibition of proliferation, although at week 5 there was 66% inhibition compared to 93% at the end of week 1.

CONCLUSIONS

1,25(OH)2D3, EB1089 and CB1093 all significantly inhibit the proliferation of HepG2 hepatoblastoma cells, with EB1089 being the most potent at lower concentrations. Inhibition can be maintained for at least 4 weeks, but is reversed after removal of vitamin D3.

Effects of chronic estradiol benzoate treatment on amygdala kindled seizures in male rats

In the female species, effect of estrogens on seizure activity is well documented, but not much is known on the effect of this ubiquitous steroid hormone on the seizure activity of the male species. In the present study, fully kindled male rats were treated with various doses (10, 30 and 50 microg/kg, i.p.) of estradiol benzoate (EB) daily, and kindled seizure parameters such as seizure stage (SS), after discharge duration (ADD) and stage 5 duration (S(5)D) were recorded at various times (0.25, 3 h and every 24 h for 96 h) after the first of daily EB treatments. While the 10-microg/kg dose of EB failed to produce any significant effect, the 30-microg/kg dose induced a triphasic effect on seizure parameters. An initially rapid increment of ADD (after 0.25 h), followed by significant decrease of all parameters at 48 h and later a significant increase in S(5)D was observed 96 h after the first of daily EB treatments. The 50-microg/kg dose of EB produced almost a similar but less marked pattern of effects. Pre-treatment with a 3-mg/kg dose of tamoxifen citrate (TAM), not only blocked the EB (30 microg/kg) effects till 72 h but also reduced the ADD and S(5)D significantly after 0.25 h, when compared to its control group. While pre-treatment with the 10-mg/kg dose of TAM only blocked the inhibitory effects of EB 48 h after the first of daily EB treatments. Administration of the latter dose of TAM alone induced a profile similar to EB treatment. These results may suggest that in male rats, estradiol treatment can both potentiate and attenuate kindled seizure parameters in a time dependent manner, and the stimulatory effects can not be blocked by TAM pre-treatment.

In vitro and in vivo suppression of growth of hepatocellular carcinoma cells by albendazole

Tubulin protein is a major target of drug molecules, and consequently, tubulin inhibitors have attracted great attention as antimitotic antitumor agents for chemotherapeutic use. It has been shown that, the benzimidazole carbamate group of antiparasitics including albendazole act by inhibiting tubulin polymerization. In this study, albendazole was tested in culture against a range of human, rat and mice hepatocellular carcinoma (HCC) cells and in vivo against human SKHEP-1 tumor growth in nude mice. Albendazole induced a dose-dependent inhibition of [(3)H]thymidine incorporation in all cell lines examined and a dramatic decline in cell numbers in SKHEP-1 cells. The inhibitory effect of albendazole was evident at the 100 nM concentration and at 1000 nM, proliferation in all cell lines examined was inhibited by more than 80%, while, proliferation of HepG2, Hep3B and SKHEP-1 were suppressed by more than 90%, compared to control. Cell cycle analysis revealed that, depending on the dose employed, albendazole can arrest SKHEP-1 cells at both G0-G1 (250 nM) and G2-M (1000 nM) phases of the cycle. Albendazole treatment (300 mg/kg per day oral for 20 days) of nude mice inoculated subcutaneously with SKHEP-1, led to profound suppression of tumor growth. Immunohistochemical analysis of these tumors revealed that compared to control, those treated with albendazole have lower growth fractions. These findings demonstrate that albendazole strongly suppresses both in vitro and in vivo proliferation of HCC cells.

The acute effects of estradiol benzoate on amygdala-kindled seizures in male rats

Using amygdaloid-kindling model of epilepsy, effects of acute estradiol treatment on seizure parameters were investigated in male rats. Fully kindled male rats were treated with various doses of estradiol benzoate (EB, 10, 30 and 50 microg/kg, i.p.) and kindling parameters such as seizure stage (SS), afterdischarge duration (ADD) and stage 5 duration (S5D) were elicited at various times (0.25, 1.5, 3 h and every 24 h for 96 h) post-drug administration. While the 10-microg/kg dose of EB failed to change seizure parameters, administration of the 30- and 50-microg/kg doses caused significant prolongation of ADD and S5D (was not changed significantly by the latter dose) at various time intervals post-drug administration. Pretreatment with the 3 mg/kg dose of tamoxifen citrate (TAM) inhibited the EB (30 microg/kg) effect, while pretreatment with the 10-mg/kg dose produced significant prolongation of ADD and S5D. These results suggest that in male amygdaloid kindled rats, acute estradiol treatment leads to an intensification of seizure that is manifested by increases in ADD and S5D. As the effect is evident 0.25 h post-EB administration and duel action of TAM in opposing the EB effect at low doses and potentiating it at the higher doses, the possibility of a genomic effect may be ruled out. The variable effects of TAM might be explained by its partial agonistic property on estrogen receptors

In vitro antiproliferative activity of a medium-chain triglyceride solution of 1,25-dihydroxyvitamin D3 in HepG2 cells

BACKGROUND

Successful targeted delivery of 1,25-dihydroxyvitamin D3 [1,25-D3] for the treatment of liver cancer would necessitate the use of an appropriate delivery agent.

MATERIALS AND METHODS

Using liver cancer cell line HepG2 in culture, we examined, the possibility of using medium-chain triglyceride (MCT) as a solvent for targeted delivery of 1,25-D3. The drug was made up in either the medium or first dissolved in MCT and subsequently diluted in the medium. Cells were exposed for 1 (acute) or 5 days (chronic) to the 2 different formulations of the drug and cell proliferation was measured by [3H]thymidine and cell count methods.

RESULTS

In chronic experiments, exposure of cells to the MCT containing formulation of 1,25-D3 led to significantly greater inhibition of cell proliferation. In the acute experiments where, 1 day 1,25-D3 treatment was followed by 4 days of incubation with normal medium (no drug, no MCT), inhibition of proliferation was more than 2 fold greater in cells exposed to the 1,25-D3/MCT preparation.

CONCLUSION

These results indicate that, 1,25-D3 dissolved in MCT probably accumulates and then acts as a sustained release drug depot formulation, in which case it may have potential for the regional treatment of liver tumors.

The use of lipiodol and medium chain triglyceride as delivery agents for hepatic arterial administration of 1, 25-dihydroxyvitamin D3--a potential new treatment for hepatocellular carcinoma

It is well established that 1, 25 dihydroxyvitamin D3 is capable of inhibiting the proliferation of a number of human cancer cell lines, including hepatoma cell lines. However, clinical usage in the treatment of cancers has been limited by its hypercalaemic effects. We hypothesised that by delivering 1, 25 dihydroxyvitamin D3 dissolved in a lipid based carrier agent as a hepatic arterial infusion it would be possible to achieve high local concentrations within hepatomas for prolonged periods, whilst avoiding high systemic concentrations and hypercalcaemia. We examined this hypothesis by administering a hepatic arterial infusion of 1, 25 dihydroxyvitamin D3 in either Lipiodol, Medium Chain Triglyceride (MCT), or saline to hepatoma bearing rats. Assay of serum and tissue concentrations revealed that this approach using lipiodol or triglyceride results in selective distribution of 1, 25-dihydroxyvitamin D3 into, and retention within hepatoma tissue and low initial systemic serum levels. Lipiodol was more effective in these respects than MCT. This method of administration has potential in the treatment of hepatoma.

In vitro and in vivo inhibition of liver cancer cells by 1,25-dihydroxyvitamin D3

Inhibitory effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on the proliferation of a variety of cancer cell lines have been extensively reported. We have studied the effect of 1,25-(OH)2D3 (10(-11)-10(-6) M) on the proliferation of a number of human and rat liver cancer cell lines. Additionally, the effect of 1,25-(OH)2D3 (0.02-0.5 microg/kg per day) on the rate of growth of liver cancer cell line xenografts in nude mice was also investigated. In vitro, proliferation of Hep-3B, PLC/PRF/5, and SKHEP-1 cells was significantly inhibited by 1,25-(OH)2D3, while HTC and Novikoff cells were more resistant to the inhibitory effects of the drug. In vivo, treatment of SKHEP-1 tumor bearing nude mice with different doses of 1,25-(OH)2D3 significantly retarded tumor growth without the development of hypercalcemia.

Intraperitoneal and intraamygdala N(6)-cyclohexyladenosine suppress hippocampal kindled seizures in rats

Effects of intraperitoneal and intraamygdala N(6)-cyclohexyladenosine (CHA), a selective adenosine A(1) receptor agonist, and 1,3-dimethyl-8-cyclopentylxanthine (CPT), a selective adenosine A(1) receptor antagonist, were examined in fully hippocampal kindled rats. Intraperitoneal administration of CHA (0. 25, 0.5 and 1 mg/kg) decreased hippocampal secondary afterdischarge duration (SAD) and amygdala afterdischarge duration (ADD). Only the 1 mg/kg dose induced a significant increase in latency to stage 4. Intraperitoneal administration of CPT (0.25, 0.5 and 1 mg/kg) induced a significant increase in stage 5 duration, hippocampal SAD and ADD. Pretreatment of animals with CPT (1 mg/kg), antagonized effects of CHA on seizure parameters. Intraamygdala microinfusion (1 microl over 2 min) of CHA (5 nM-1 mM) significantly reduced hippocampal SAD and amygdala ADD. These effects were antagonized by intraamygdala CPT (1 microM). Results obtained suggest that in hippocampal kindled rats, amygdala may be regarded as a relay point for AD propagation specially in recruit activity of the hippocampus.

1,25-dihydroxyvitamin D3 dissolved in lipiodol produces a sustained antiproliferative effect in the human hepatoblastoma cell line HepG2

The steroid hormone 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] has potential to be used as an anti-tumor agent, but its clinical application has been restricted by the strong systemic calcemic activity. Regional administration of the drug dissolved in lipiodol, might be a way of selectively delivering high concentrations of the drug to lipiodol avid tumor cells without causing systemic side effects. In acute (1 day treatment) and chronic (5 days treatment) experiments, efficacy of the drug dissolved in ethanol (control) or lipiodol and subsequently diluted in the culture medium was tested in vitro against the hepatoblastoma cell line HepG2. Using [3H]thymidine incorporation and cell count, antiproliferative effects of 1,25-(OH)2D3 dissolved in the two different solvents was compared. Microscopic examination of cells exposed to the lipiodol containing media revealed intra-cellular presence of the oil in abundance. Chronic treatment of cells with either formulation of 1,25-(OH)2D3 resulted in profound inhibition of cell proliferation. However, exposure of cells to 1,25-(OH)2D3 in lipiodol was followed by significantly greater and lasting inhibition of cell proliferation in both acute and chronic studies. These results indicate that, 1,25-(OH)2D3 dissolved in lipiodol probably acts as a sustained release drug depot formulation, in which case it could have some potential for the regional treatment of liver tumors.

Anticonvulsant action of 2-chloroadenosine injected focally into the perirhinal cortex in amygdaloid kindled rats

Possible anticonvulsant effects of 2-chloroadenosine injected focally into the perirhinal cortex of amygdala kindled rats were investigated over a 2 h period. Animals were microinfused (1 microl) with 2-chloroadenosine (2-CLA; 5, 10, 15, 25 and 100 nM) or artificial cerebrospinal fluid applied through a cannula located in the perirhinal cortex. At the doses employed, 2-CLA significantly reduced afterdischarge duration and stage 5 seizure duration. The latency to stage 4 seizure was increased only at the highest dose of 2-CLA (100 nM), while even at this dose no significant change in seizure stage could be seen. The maximum effect of 2-CLA was obtained 30 min after microinfusion of the drug. Pre-treatment (intraperirhinal cortex) of animals with the nonselective adenosine antagonist, caffeine (50 microM; 1 microl), blocked the anticonvulsant activity of 2-CLA. These results suggest that adenosine receptors located in the perirhinal cortex may play an important role in the suppression of seizure activity elicited from the amygdala.

The fruit essential oil of Pimpinella anisum exerts anticonvulsant effects in mice

This study investigates anticonvulsant effects of an essential oil of the fruits of Pimpinella anisum (Umbelliferae), a folkloric remedy in the Iranian traditional medicine, against seizures induced by pentylenetetrazole (PTZ) or maximal electroshock (MES) in male mice. The essential oil suppressed tonic convulsions induced by PTZ or MES. It also elevated the threshold of PTZ-induced clonic convulsions in mice. The essential oil produced motor impairment. However, this effect was not observed at the doses and time courses needed for anticonvulsant activity.

Evaluation of the anticonvulsant activity of the essential oil of Eugenia caryophyllata in male mice

In this study, the effect of an essential oil of Eugenia caryophyllata (Myrtaceae), an antiepileptic remedy in Iranian folk medicine, against seizures induced by maximal electroshock (MES) or pentylenetetrazole (PTZ) in male mice was studied. The essential oil exhibited anticonvulsant activity against tonic seizures induced by MES. Although it was not effective against clonic convulsions induced by intraperitoneal administration of PTZ, the seizure threshold which was determined by an increase in the dose of intravenously infused PTZ required to induce clonus, was elevated by the essential oil. In addition, at some anticonvulsant doses, the essential oil produced motor impairment on the rotarod.

Evaluation of the anticonvulsant profile of progesterone in male amygdala-kindled rats

While there is clinical evidence that progesterone has anticonvulsant activity in women with complex partial seizures, previous studies on the anticonvulsant effect of progesterone in experimental animal models are inconclusive. Moreover, the effect of progesterone on seizure parameters in fully amygdala-kindled rats which best resemble complex partial seizures has not been evaluated. Therefore, in the present work the anticonvulsant effect of progesterone at doses of 10, 30, 60 and 75 mg/kg in fully amygdala-kindled male rats was studied. Only at the high and sedative dose of 75 mg/kg, progesterone suppressed behavioral seizures and afterdischarges elicited 10 min after intraperitoneal (i.p.) administration. Pretreatment with the progesterone antagonist, 17beta-hydroxy-11beta-(4-dimethylaminophenyl)-17alpha-(prop- 1-ynyl)-estra-4,9-dien-3-one (RU 38486) at the dose of 3 mg/kg did not inhibit the anticonvulsant activity of progesterone, while pretreatment with the GABA(A) receptor antagonist, bicuculline (2 mg/kg) blocked the anticonvulsant effect of progesterone. Neither RU 38486 nor bicuculline had any effect on the seizure parameters. These findings suggest that only at large and sedative doses, progesterone has some anticonvulsant activity in male amygdala-kindled rats which may be partly mediated via the GABA(A) receptor complex interaction.

Intra-amygdala infusion of 2-chloroadenosine suppresses amygdala-kindled seizures

The seizure-modulating effects of 2-chloroadenosine (2-CLA) infused directly into the amygdala were investigated. Different groups of amygdala-kindled rats were infused (1 microliter) with 2-CLA (0.25, 1, 10 and 25 nM), caffeine (200 microM and 2 mM), a combination of the two or artificial cerebrospinal fluid (ACSF) applied directly through a cannula located in the amygdala. Infusion of 2-CLA dramatically suppressed seizure stage (SS), after discharge duration (ADD) and stage 5 seizure duration (S5D), while the latency to bilateral forelimb clonus (S4L) was significantly prolonged. These anticonvulsant effects were evident after 5 min, reached a maximum at the 60 min time point and were still detectable 360 min post-2-CLA infusion. Pretreatment with caffeine blocked the anticonvulsant effects of 2-CLA dose-dependently. These results may suggest that in amygdaloid-kindled rats, adenosine receptors located in the amygdala play a major role in the expression of the anticonvulsant activity of 2-CLA.

Effect of intraperitoneal and intrahippocampal (CA1) 2-chloroadenosine in amygdaloid kindled rats

Effects of intraperitoneal and intrahippocampal 2-chloroadenosine and caffeine were examined in fully kindled amygdaloid rats. Intraperitoneal administration of 2-chloroadenosine (5 and 10 mg/kg) decreased afterdischarge duration, stage 5 seizure duration and prolonged time taken to reach stage 4 seizure. Only the 10 mg/kg dose induced a significant reduction in seizure stage. Intraperitoneal administration of caffeine (50 mg/kg) increased both afterdischarge duration and stage 5 seizure duration but did not significantly alter other parameters. Intrahippocampal microinfusion of 2-chloroadenosine (1 mM) or caffeine (2 mM) did not alter any of the measured seizure parameters. Intraperitoneal but not intrahippocampal pretreatment of animals with caffeine (50 mg/kg and 2 mM, respectively) blocked the anticonvulsant effects induced by intraperitoneal administration of 2-chloroadenosine. It may therefore be concluded that the adenosine A1 receptors of the CA1 region of the hippocampus do not play a role in mediating the anticonvulsant effects of intraperitoneally administered 2-chloroadenosine in amygdaloid kindled rats.

Evidence for serotonergic system involvement in the effect of morphine on gastrointestinal motility in the rat

1. Intestinal motility was measured by the transit of charcoal meal through the small intestine of the rat. 2. Morphine given subcutaneously induced a reduction in the gastrointestinal transit (GIT), and the response was dose-dependent (0.1-2.5 mg/kg). 3. The inhibitory effect of morphine was antagonized by prior subcutaneous administration of naloxone (1 mg/kg). 4. Depletion of serotonergic neurons by para-chlorophenylalanine (100 mg/kg, ip, 3 days) completely abolished the inhibitory action of morphine. 5. Methysergide (5 mg/kg, sc) and ketanserin (5 mg/kg, sc) also reduced the morphine effect. 6. Destruction of serotonergic neurones by intracerebroventricular injection of 5,7-dihydroxytryptamine (20 mu/kg) abolished the effect of morphine. 7. These observations provide some evidence for the involvement of a central serotonergic system in the effect of morphine on gastrointestinal motility.

Inhibition of aromatase activity in the rat by aminoglutethimide and related compounds

Two compounds possessing aromatase inhibitory activity have been evaluated for their effects on oestradiol (E2) biosynthesis in the rat. These compounds, structurally related to aminoglutethimide (1), were administered intra-peritoneally at two dose levels to 10 week old female rats previously treated with pregnant mares' serum gonadotrophin (PMSG, 100 i.u. subcutaneously every other day for 9 days). Three hours after dosing, blood was collected and plasma oestradiol levels determined by RIA. Aminoglutethimide, 3-(4'-aminophenyl-3-ethylpyrrolidine-2,5-dione (2) and N-methyl-3-(4'-aminophenyl)-3-ethylpyrrolidine-2,5-dione (3) decreased E2 blood levels by 98, 97 and 82% of control levels respectively (n = 6) at a dose of 50 mg/kg. Similarly effective inhibition was also observed at a dose of 25 mg/kg (n = 4). Ovarian aromatase activity, assessed by incubating the homogenised ovaries of treated rats with tritium-labelled androstenedione (0.2 microM) or testosterone (1 microM), indicated that residual enzyme activity was reduced compared with controls. Aminoglutethimide, and the new pyrrolidinedione aromatase inhibitors 2 and 3, are therefore effective inhibitors of E2 biosynthesis in the rat with functioning ovarian activity.