Malignant melanoma is the most aggressive and deadliest form of skin cancer due to its highly metastatic potential, which calls for new and improved therapies. Cationic antimicrobial peptides (CAPs) are naturally occurring molecules found in most species, in which they play a significant role in the first line of defense against pathogens, and several CAPs have shown promising potential as novel anticancer agents. Structure–activity relationship studies on the CAP bovine lactoferricin allowed us to de novo design short chemically modified lytic anticancer peptides. In the present study, we investigated the in vivo antitumor effects of LTX-315 against intradermally established B16 melanomas in syngeneic mice. Intratumoral administration of LTX-315 resulted in tumor necrosis and the infiltration of immune cells into the tumor parenchyma followed by complete regression of the tumor in the majority of the animals. LTX-315 induced the release of danger-associated molecular pattern molecules such as the high mobility group box-1 protein in vitro and the subsequent upregulation of proinflammatory cytokines such as interleukin (IL) 1β, IL6 and IL18 in vivo. Animals cured by LTX-315 treatment were protected against a re-challenge with live B16 tumor cells both intradermally and intravenously. Together, our data indicate that intratumoral treatment with LTX-315 can provide local tumor control followed by protective immune responses and has potential as a new immunotherapeutic agent.Electronic supplementary materialThe online version of this article (doi:10.1007/s00262-014-1540-0) contains supplementary material, which is available to authorized users.
Cell adhesion and migration is largely dependent on integrin binding to extracellular matrix, and several signalling pathways involved in these processes have been shown to be modified by reactive oxygen species (ROS). In fact, integrin activation is linked to increased ROS production by NADPH-oxidases, 5-lipoxygenase, and release from mitochondria. Cell migration is intimately linked to degradation of the extracellular matrix, and activated matrix metalloproteinases (MMPs) are a prerequisite for cancer cell invasion and metastasis. In this minireview, we focus on the interplay between integrin-mediated ROS production and MMP expression as well as its biological and pathobiological significance.
SUMMARYThe life strategy of the anadromous Arctic charr (Salvelinus alpinus) includes several months of voluntary fasting during overwintering in freshwater, leading to emaciation prior to seawater migration in spring. In this study we compared changes in condition, substrate utilization and liver metabolism between captive anadromous charr subjected to food deprivation during late winter and spring, and conspecifics fed in excess. In March, nine out of the 10 sampled fed fish had not eaten, indicating that they were in a voluntary anorexic state. In June, the fed fish were eating and all had higher body mass, condition factor and adiposity than in March. In fasted fish there were only small decreases in body mass, condition factor and adiposity between March and May, but all these parameters decreased markedly from May to June. The fasted fish were depleted in fat and glycogen in June, had suppressed activity of hepatic enzymes involved in lipid metabolism (G6PDH and HOAD) and seemed to rely on proteinderived glucose as a major energy source. This was associated with upregulated liver gene expression of leptin A1, leptin A2, SOCS1, SOCS2 and SOCS3, and reduced IGF-I expression. In an in vitro study with liver slices it was shown that recombinant rainbow trout leptin stimulated SOCS1 and SOCS3 expression, but not SOCS2, IGF-I or genes of enzymes involved in lipid (G6PDH) and amino acid (AspAT) metabolism. It is concluded that liver leptin interacts with SOCS in a paracrine fashion to suppress lipolytic pathways and depress metabolism when fat stores are depleted.
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γ-Glutamyltransferase (GGT) plays a significant role in antioxidant defence and participates in the metabolism of glutathione (GSH). The enzyme is up-regulated after acute oxidative stress and during pro-oxidant periods, but the underlying regulatory mechanisms are not well known. The present investigation studied whether the endogenous reactive oxygen species (ROS) level was a determinant for GGT expression. A substantial amount of ROS is produced through the NADPH oxidase (NOX) system and knockdown of p22phox, a sub-unit of NOX1-4, resulted not only in reduced ROS levels but also in reduced GGT expression in human endometrial carcinoma cells. Phorbol-12-myristate-13-acetate (PMA) is an activator of NOX and it was found that PMA treatment of human colon carcinoma cells both increased cellular ROS levels and subsequently up-regulated GGT expression. On the other hand, the NOX inhibitor apocynin reduced ROS levels as well as GGT expression. The GGT mRNA sub-type A was increased after PMA-induced NOX activation. These results demonstrate that ROS generated from NOX enzymes are a significant determinant for GGT expression and activity.
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