Antinociceptive profile of potent opioid peptide AM94, a fluorinated analogue of biphalin with non-hydrazine linker.

AM94 is a fluorinated analog of biphalin with non-hydrazine linker that has an in vitro affinity for µ-opioid and δ-opioid receptors tenfold higher than biphalin. Furthermore, in vivo evaluation in rats showed that AM94 has in hot plate test - after both intracerebroventricular and intravenous administrations - a greater and more durable efficacy than biphalin. Here, the antinociceptive profile of AM94 is further evaluated by following two different administration routes, intrathecal and subcutaneous, and two different animal species, rats and mice. The analgesic potency of AM94 is compared with that of both the parent peptide biphalin and morphine. Results show that in rats (tail flick test) and in mice (formalin test), AM94 has a higher and more durable analgesic effect than biphalin after intrathecal and subcutaneous administrations. Conformational properties of biphalin and AM94 were also investigated by variable-temperature (1)H NMR and energy minimization.

α-Adrenoceptor stimulation attenuates melanoma growth in mice.

BACKGROUND AND PURPOSE: Recently, ß-adrenoceptor blockade has emerged as a potential strategy to inhibit melanoma growth. It remains to be ascertained whether ß-adrenoceptor stimulation by circulating catecholamines increases melanoma growth in mice. EXPERIMENTAL APPROACH: B16F10 melanoma-bearing mice were used to evaluate effects of adrenaline and specific adrenoceptor (AR) ligands on tumour volume. AR expression and effects of AR ligands on cell viability, production of mitochondrial reactive oxygen species (mROS), and proliferation activity in B16F10 cells, were determined by biochemical analyses. KEY RESULTS: Real-time polymerase chain reaction (qPCR) analyses revealed that B16F10 cells express α1B-, α2A-, α2B- and ß2-ARs. We found that treatment with the α- and ß-AR agonist adrenaline or with the synthetic catecholamine isoprenaline, which selectively stimulates ß-ARs, did not affect melanoma growth. Conversely, adrenaline reduced tumour growth in mice cotreated with propranolol, a ß1ß2-AR antagonist. Adrenaline had no effect in tumour-bearing ß1ß2-AR knockout mice, in which ß1- and ß2-ARs are lacking, but it reduced tumour growth when co-administered with propranolol suggesting that tumour ß2-ARs negatively regulate adrenaline antitumour activity. Additionally, we found that α1-AR stimulation with cirazoline yielded a decrease in B16F10 melanoma size. These effects on melanoma growth were paralleled by reduced cell viability and proliferation activity as well as increased mROS production in α1-AR-stimulated B16F10 cells. Decreased viability, proliferation and mitochondrial function in B16F10 cells also occurred after α2-AR stimulation by α2-AR agonist ST91. CONCLUSIONS AND IMPLICATIONS: In the B16F10 melanoma model, stimulation of α-AR subtypes yields in vivo and in vitro anticancer activity.

Effect of Modified Alkaline Supplementation on Syngenic Melanoma Growth in CB57/BL Mice.

Tumor extracellular acidity is a hallmark of malignant cancers. Thus, in this study we evaluated the effects of the oral administration of a commercially available water alkalizer (Basenpulver®) (BP) on tumor growth in a syngenic melanoma mouse model. The alkalizer was administered daily by oral gavage starting one week after tumor implantation in CB57/BL mice. Tumors were calipered and their acidity measured by in vivo MRI guided 31P MRS. Furthermore, urine pH was monitored for potential metabolic alkalosis. BP administration significantly reduced melanoma growth in mice; the optimal dose in terms of tolerability and efficacy was 8 g/l (p< 0.05). The in vivo results were supported by in vitro experiments, wherein BP-treated human and murine melanoma cell cultures exhibited a dose-dependent inhibition of tumor cell growth. This investigation provides the first proof of concept that systemic buffering can improve tumor control by itself and that this approach may represent a new strategy in prevention and/or treatment of cancers.