Evaluation of serum insulin-like growth factor-1 and 26S proteasome concentrations in healthy dogs and dogs with chronic diseases depending on body condition score.

In patients suffering from chronic diseases, the objective assessment of metabolic states could be of interest for disease prognosis and therapeutic options. Therefore, the aim of this study was to assess insulin-like growth factor-1 (IGF-1) and 26S proteasome (26SP) in healthy dogs and dogs suffering from chronic diseases depending on their body condition score (BCS) and to examine their potential for objective assessment of anabolic and catabolic states. Serum concentrations of IGF-1, an anabolic hormone, and 26SP, a multiprotein complex which is part of the ubiquitin-proteasome pathway, by which the majority of endogenous proteins including the muscle proteins are degraded, were measured in 21 healthy dogs and 20 dogs with chronic diseases by canine ELISA. The concentrations of IGF-1, 26SP and their ratio (IGF-1/26SP) were set in relationship to the BCS of the dogs. When examining healthy and chronically diseased dogs separately, a positive correlation between IGF-1 and the BCS was observed in the healthy group and a negative correlation between 26SP and the BCS was noted in dogs with chronic diseases. Further, dogs suffering from chronic diseases showed higher 26SP concentrations and lower values for IGF-1/26SP than the healthy dogs. Overall, we detected a negative correlation between 26SP and the BCS and a positive correlation between IGF-1/26SP and the BCS. The results of our study indicate usability of IGF-1 for description of anabolic states, while 26SP could be useful for detection and description of catabolic states. Finally, the ratio IGF-1/26SP seems to be promising for assessment of metabolic states.

26S proteasome and insulin-like growth factor-1 in serum of dogs suffering from malignant tumors.

Studies in humans have shown that the ubiquitin-proteasome pathway and the insulin-like growth factor axis are involved in carcinogenesis, thus, components of these systems might be useful as prognostic markers and constitute potential therapeutic targets. In veterinary medicine, only a few studies exist on this topic. Here, serum concentrations of 26S proteasome (26SP) and insulin-like growth factor-1 (IGF-1) were measured by canine enzyme-linked immunosorbent assay (ELISA) in 43 dogs suffering from malignant tumors and 21 clinically normal dogs (control group). Relationships with tumor size, survival time, body condition score (BCS), and tumor entity were assessed. The median 26SP concentration in the tumor group was non-significantly higher than in the control group. However, dogs with mammary carcinomas displayed significantly increased 26SP levels compared to the control group and dogs with tumor size less than 5 cm showed significantly increased 26SP concentrations compared to dogs with larger tumors and control dogs. 26SP concentrations were not correlated to survival time or BCS. No significant difference in IGF-1 levels was found between the tumor group and the control group; however, IGF-1 concentrations displayed a larger range of values in the tumor group. Dogs with tumors greater than 5 cm showed significantly higher IGF-1 levels than dogs with smaller tumors. The IGF-1 concentrations were positively correlated to survival time, but no correlation with BCS was found. Consequently, serum 26SP concentrations seem to be increased in some dogs suffering from malignant tumors, especially in dogs with mammary carcinoma and smaller tumors. Increased serum IGF-1 concentrations could be an indication of large tumors and a poor prognosis.

Des études chez l'humain ont démontré que la voie ubiquitine-protéasome et l'axe du facteur de croissance apparenté à l'insuline sont impliqués dans la carcinogénèse, et ainsi, des composantes de ces systèmes pourraient être utiles en tant que marqueurs du pronostic et constituer des cibles thérapeutiques potentielles. En médecine vétérinaire, seules quelques études existent sur ce sujet. Dans cette étude, les concentrations sériques de protéasome 26S (26SP) et du facteur de croissance 1 apparenté à l'insuline (IGF-1) ont été mesurés par réaction immunoenzymatique (ELISA) chez 43 chiens souffrant de tumeurs malignes et 21 chiens cliniquement normaux (groupe témoin). Les associations entre la taille des tumeurs, le temps de survie, le pointage de la condition corporelle (PCC) et le type de tumeurs ont été évaluées. La concentration médiane de 26SP dans le groupe avec tumeur était plus élevée que celle du groupe témoin mais de manière non-significative. Toutefois, les chiens avec des carcinomes mammaires montraient des quantités significativement augmentées de 26SP comparativement au groupe témoin et les chiens avec des tumeurs dont la taille était de moins de 5 cm avaient des concentrations de 26SP significativement augmentées comparativement aux chiens avec des tumeurs plus grosses et aux chiens du groupe témoin. Les concentrations de 26SP n'étaient pas corrélées au temps de survie ou au PCC. Aucune différence significative dans les niveaux d'IGF-1 ne fut trouvée entre le groupe avec tumeur et le groupe témoin; toutefois, les concentrations d'IGF-1 s'étendaient sur un plus large spectre dans le groupe avec tumeur. Les chiens avec des tumeurs plus large que 5 cm avaient des concentrations d'IGF-1 significativement plus élevées que les chiens avec des tumeurs plus petites. Les concentrations d'IGF-1 étaient corrélées positivement avec le temps de survie, mais aucune corrélation avec le PCC ne fut trouvée. Conséquemment, les concentrations de 26SP semblent être augmentées chez quelques chiens souffrant de tumeurs malignes, et plus spécialement les chiens avec des carcinomes mammaires et des plus petites tumeurs. Des concentrations augmentées d'IGF-1 pourraient être une indication d'une grosse tumeur et d'un pronostic sombre.(Traduit par Docteur Serge Messier).