The Effect of Urethan and 7,12-Dimethylbenz[a]Anthracene on Organ Cultures of Newborn and Adult Mouse Thymuses

Thymuses of newborn and adult mice were maintained as organ cultures for 20 days. A 24 hour treatment with urethan or with 7,12-dimethylbenz(a)anthracene (DMBA) induced necrosis of the peripheral zone of the cortex in both the newborn and adult cultured thymuses. In all the DMBA treated thymuses and the newborn thymuses treated with urethan, the necrosis eventually involved a large part of the organs. In the adult thymuses treated with urethan the necrosis appeared notably reduced at the end of the 20 day observation period.

Abstract B38: Photochemical internalisation for the local delivery of chemotherapy in prostate cancer

• Introduction

Prostate cancer is fifth leading cause of death from cancer in men. Although chemotherapy is the gold standard treatment for a wide range of cancers including the prostate, there are several limitations (systemic toxicity, multidrug resistance or inadequate cellular delivery) and there is growing interest in developing focal therapies when appropriate.

Photochemical Internalisation (PCI) is a focal light-triggered drug delivery system, which combines low dose Photodynamic Therapy (PDT) with chemotherapy agents to enhance delivery of the agents to their specific subcellular target. PCI is particularly suitable for agents prone to endolysosomal sequestration, thererefore the photosensitisers (PS) used for PCI localise in endolysosomal membranes which upon visible light exposure leads to the production of reactive oxygen species (ROS), causing photooxidative disruption of membranes and subsequent cytosolic release of the entrapped agents. These will then reach their intended targets more efficiently, improving efficacy and potentially reducing the therapeutic dose.

The present project focuses on the use of PCI to deliver Saporin, a ribosome inactivating (RIP) type 1 protein. RIPs are able to cause permanent damage to eukaryotic ribosomes; however, despite its intrinsic high toxicity, endolysosomal sequestration impairs its ability to inhibit protein synthesis.

• Aim

To assess the potential of PCI for enhanced delivery of Saporin in human and rat prostate cancer cells. In addition, a CXCR4-targeted peptide-PS conjugate was tested.

• Materials & Methods

Porphyrin and chlorin-based PS were co-administered with Saporin. Cells were incubated for 24hrs with different drug combinations then exposed to light, and cell viability was measured at different time points post illumination using the MTT assay. Subcellular location of Saporin and PS were observed using confocal microscopy.

• Results

PCI resulted in a synergistic effect between sub-lethal PDT and Saporin. Despite minimal cell kill when the toxin or PS were administered alone, PCI delivery enhanced Saporin cytotoxicity using only 20pM in the rat Mat-LyLu and 2nM in PC3 human cell lines. PCI elicits up to 1.5-fold higher efficacy in cell kill vs. PDT 48hrs after light treatment and 3.5-fold higher 96hrs after light treatment in rat and human prostate cancer cells accordingly (p<0.05). In addition, PS doses were reduced by 20 times when targeted against CXCR4 receptor (overexpressed in prostate cancer among others). This resulted in 75% reduction of cell viability compared to 79% using the 20-fold higher dose of untargeted PS. Moreover, a 3-fold higher efficacy in cell kill of PCI vs. PDT 96hrs after light treatment in human cells was observed.

Intracellular redistribution following endolysosomal release of fluorescently labelled Saporin and PS following illumination was confirmed with confocal microscopy.

• Conclusions

These results demonstrate the potential of PCI for prostate cancer treatment in vitro and in vivo tumour experiments are in progress.

Citation Format: ALEJANDRA MARTINEZ DE PINILLOS, RUGGERO DONDI, L. WANG, ELNAZ YAGHINI, JOSEPHINE H. WOODHAMS, CAROLINE M. MOORE, IAN M. EGGLESTON, ALEXANDER J. MACROBERT. Photochemical internalisation for the local delivery of chemotherapy in prostate cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B38.

EFFECT OF SINGLE-WALL CARBON NANOTUBE ON SOYBEAN (GLYCINE MAX) REGENERATION FROM MATURE COTYLEDONARY NODE EXPLANTS

One of the major limitations in producing transgenic soybeans using the agrobacterium-mediated cotyledonary-node method is low regeneration frequency. An improved highly efficient regeneration system of soybean was established herein. Cotyledonary node explants were placed in shoot initiation medium with single-wall carbon nanotube (SWNT) for adventitious shoots regeneration, and adventitious shoots were subcultured in shoot elongation medium with SWNT for shoot elongation and rooting. 40 mg/L SWNT supplemented in shoot initiation medium was found to be the optimal concentration with shoots regeneration frequency significantly increased by 21.5% compared with the control treatment, while for 4 mg/L and 400 mg/L, the increase was 4.6% and 6.5%, respectively. Faster elongation and rooting of adventitious shoots was observed in shoot elongation medium with 40 mg/L SWNT. Soybean plantlet formation frequency within the limited four weeks supplemented with 40 mg/L SWNT reached 48.4% while in the other three treatments: 4 mg/L, 400 mg/L and control, 0% were observed. These results indicate that supplement of SWNT in the soybean medium can efficiently promote adventitious shoots formation frequency, increase plantlet formation frequency and shorten the regeneration period.

Mice overexpressing wild-type human alpha-synuclein display alterations in colonic myenteric ganglia and defecation

BACKGROUND

Prevalent non-motor symptoms of Parkinson's disease (PD) include gastrointestinal motor impairments and advanced stage PD displays pathological aggregates of α-synuclein in colonic enteric neurons. We previously showed that 12 months old mice overexpressing human wild type (WT) α-synuclein under the Thy1 promoter (Thy1-aSyn) displayed colonic motor dysfunction. We investigated functional gut alterations at earlier ages and histological correlates.

METHODS

Defecation, gastric emptying (GE), and immunostaining for α-synuclein, peripheral choline acetyltransferase (pChAT), tyrosine hydroxylase (TH), neuronal nitric oxide synthase (nNOS), and vasoactive intestinal peptide (VIP) in distal colon myenteric plexuses were assessed in male Thy1-aSyn compared to littermate WT mice.

KEY RESULTS

Thy1-aSyn mice aged 2.5-3 or 7-8 months old had 81% and 55% reduction in fecal pellet output, respectively, in the first 15 min of exposure to a novel environment. The reduction remained significant in the older group for 2-h, and subsequent refeeding resulted also in a 60% and 69% reduction of defecation in the first hour, respectively. Thy1-aSyn mice (8-10 months) displayed increased α-synuclein in the myenteric plexuses with abundant varicose terminals surrounding pChAT-immunoreactive (ir) neurons, and only a few, nNOS-ir neurons. There were no conspicuous changes in pChAT- and nNOS-ir neurons, or TH- and VIP-ir nerve fibers. Thy1-aSyn mice aged 4-18 months had normal GE.

CONCLUSIONS & INFERENCES

The occurrence of over-production of pre-synaptic α-synuclein in colonic myenteric ganglia several months before the loss of striatal dopamine may provide an anatomical basis for interference with cholinergic neuronal activation, causing an early impairment in defecation to stimuli.

Mast-Cell Degranulation Induced by Physical Stimuli Involves the Activation of Transient-Receptor-Potential Channel TRPV2

A characteristic of mast cells is the degranulation in response to various stimuli. Here we have investigated the effects of various physical stimuli in the human mast-cell line HMC-1. We have shown that HMC-1 express the transient receptor potential channels TRPV1, TRPV2 and TRPV4. In the whole-cell patch-clamp configuration, increasing mechanical stress applied to the mast cell by hydrostatic pressure (–30 to –90 cm H2O applied via the patch pipette) induced a current that could be inhibited by 10 µM of ruthenium red. This current was also inhibited by 20 µM SKF96365, an inhibitor that is among TRPV channels specific for the TRPV2. A characteristic of TRPV2 is its activation by high noxious temperature; temperatures exceeding 50 °C induced a similar ruthenium-red-sensitive current. As another physical stimulus, we applied laser light of 640 nm. Here we have shown for the first time that the application of light (at 48 mW for 20 min) induced an SKF96365-sensitive current. All three physical stimuli that led to activation of SKF96365-sensitive current also induced pronounced degranulation in the mast cells, which could be blocked by ruthenium red or SKF96365. The results suggest that TRPV2 is activated by the three different types of physical stimuli. Activation of TRPV2 allows Ca2+ ions to enter the cell, which in turn will induce degranulation. We, therefore, suggest that TRPV2 plays a key role in mast-cell degranulation in response to mechanical, heat and red laser-light stimulation.

Central administration of pan-somatostatin agonist ODT8-SST prevents abdominal surgery-induced inhibition of circulating ghrelin, food intake and gastric emptying in rats

BACKGROUND

  Activation of brain somatostatin receptors (sst(1-5) ) with the stable pan-sst(1-5) somatostatin agonist, ODT8-SST blocks acute stress and central corticotropin-releasing factor (CRF)-mediated activation of endocrine and adrenal sympathetic responses. Brain CRF signaling is involved in delaying gastric emptying (GE) immediately post surgery. We investigated whether activation of brain sst signaling pathways modulates surgical stress-induced inhibition of gastric emptying and food intake.

METHODS

Fasted rats were injected intracisternally (i.c.) with somatostatin agonists and underwent laparotomy and 1-min cecal palpation. Gastric emptying of a non-nutrient solution and circulating acyl and desacyl ghrelin levels were assessed 50min post surgery. Food intake was monitored for 24 h.

KEY RESULTS

The abdominal surgery-induced inhibition of GE (65%), food intake (73% at 2h) and plasma acyl ghrelin levels (67%) was completely prevented by ODT8-SST (1μg per rat, i.c.). The selective sst(5) agonist, BIM-23052 prevented surgery-induced delayed GE, whereas selective sst(1) , sst(2) , or sst(4) agonists had no effect. However, the selective sst(2) agonist, S-346-011 (1μg per rat, i.c.) counteracted the abdominal surgery-induced inhibition of acyl ghrelin and food intake but not the delayed GE. The ghrelin receptor antagonist, [D-Lys(3) ]-GHRP-6 (0.93mg kg(-1) , intraperitoneal, i.p.) blocked i.p. ghrelin-induced increased GE, while not influencing i.c. ODT8-SST-induced prevention of delayed GE and reduced food intake after surgery.

CONCLUSIONS & INFERENCES

ODT8-SST acts in the brain to prevent surgery-induced delayed GE likely via activating sst(5) . ODT8-SST and the sst(2) agonist prevent the abdominal surgery-induced decrease in food intake and plasma acyl ghrelin indicating dissociation between brain somatostatin signaling involved in preventing surgery-induced suppression of GE and feeding response.

Central somatostatin receptor 1 activation reverses acute stress-related alterations of gastric and colonic motor function in mice

BACKGROUND

Corticotropin-releasing factor (CRF) signaling induced by stress is well established to delay gastric emptying (GE) and stimulate colonic functions. The somatostatin receptor (sst(1-5) ) agonist, ODT8-SST acts in the brain to inhibit stress-induced adrenocorticotropic hormone and epinephrine secretion. We investigated whether ODT8-SST acts in the brain to influence stress-related alterations of gastric and colonic motor function and sst receptor subtype(s) involved.

METHODS

Peptides were injected intracerebroventricularly (i.c.v.) under short isoflurane anesthesia and GE, fecal pellet output (FPO) and distal colonic motility monitored in conscious mice.

KEY RESULTS

The stress of acute anesthesia/vehicle i.c.v. injection reduced GE by 67% and increased defecation by 99% compared to non-injected controls. Both responses were abolished by ODT8-SST (1μg= 0.75nmol) or sst(1) agonist (0.65-1.95nmol). The sst(1) agonist (1.95nmol) also prevented the abdominal surgery-induced delayed GE. Octreotide (sst(2)  >sst(5)  > sst(3) ) and the sst(2) or sst(4) agonists (1μg=0.78 or 0.70nmol, respectively) injected i.c.v. did not influence FPO while i.c.v. somatostatin-28 mimicked ODT8-SST's effect. The ODT8-SST-induced increased food intake was inhibited by i.c.v. sst(2) antagonist while the reduced FPO was unchanged. ODT8-SST i.c.v. reduced distal colonic motility in semi-restrained mice compared with vehicle and blocked water avoidance- and i.c.v. CRF (0.5μg=0.09nmol)-induced stimulated FPO while a similar colonic secretomotor response to i.p. 5-hydroxytryptophane (10mgkg(-1) =36.4μmol kg(-1) ) was unaltered. Conclusions & Inferences  ODT8-SST counteracts stress/i.c.v. CRF-related stimulation of colonic motor function and delayed GE which can be reproduced mainly by activation of sst(1) receptors. These data opens new insight to brain somatostatinergic signaling pathways interfering with brain circuitries involved in gut motor responses to acute stress.