mRNA expression of tumor-associated genes in canine grade I meningiomas

The expression of platelet-derived growth factor and its receptor in canine and feline meningiomas

Feline meningiomas usually have benign biological behavior, while canine and human meningiomas are often classified as grade 2 or 3. Activation of the platelet-derived growth factor (PDGF) and its receptor signal pathway through PDGFβ/Rβ autocrine and paracrine is considered to play an important role in the tumor proliferation and malignant transformation of human meningiomas. However, there have been few studies about the expression of these molecules in canine meningiomas and no studies about their expression in feline meningiomas. We analyzed the PDGFα/Rα and PDGFβ/Rβ expression in canine and feline meningiomas by immunohistochemistry and western blotting. Immunohistochemically, most canine meningiomas showed the expression of PDGFα (42/44; 95.5%), PDGFRα (44/44; 100%) and PDGFRβ (35/44; 79.5%), and a few showed the expression of PDGFβ (8/44; 18.2%). In contrast, feline meningiomas were immunopositive for PDGFRα and PDGFRβ in all cases (14/14; 100%), while no or a few cases expressed PDGFα (0/14; 0%) and PDGFβ (2/14; 14.3%). Western blotting revealed specific bands for PDGFα, PDGFRα and PDGFRβ, but not for PDGFβ in a canine meningioma. In a feline meningioma, specific bands for PDGFRα and PDGFRβ were detected, but not for PDGFα and PDGFβ. These results suggested that canine meningiomas commonly express PDGFα/Rα, and thus autocrine or paracrine PDGFα/Rα signaling may be involved in their initiation and progression. Moreover, PDGF negativity may be related to benign biological behavior and a low histopathological grade in feline meningioma.

Comparison of vascular endothelial growth factor/vascular endothelial growth factor receptor 2 expression and its relationship to tumor cell proliferation in canine epithelial and mesenchymal tumors

The vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) signaling pathway plays an important role in tumor angiogenesis. VEGFR2 is expressed not only in vascular endothelial cells but also in tumor cells; however, the relationship of VEGF/VEGFR2 expression and tumor proliferation has yet to be elucidated. In addition, since several studies have reported that VEGFR2 inhibitors are more effective against epithelial tumors than mesenchymal tumors, there may be a difference in VEGF/VEGFR2 expression between epithelial and mesenchymal tumors. The purpose of this study was to elucidate differences in VEGF/VEGFR2 expression between epithelial and mesenchymal tumors and the relationship of VEGF/VEGFR2 expression and proliferation in canine tumor cells. We assessed 29 epithelial and 21 mesenchymal canine tumors for microvessel density (MVD), mRNA transcription levels of von Willebrand Factor (vWF) and endoglin, expression of VEGF, VEGFR2, and phosphorylated VEGFR2 (pVEGFR2), and proliferation index (PI) using real-time reverse transcription polymerase chain reaction and immunohistochemistry. VEGFR2 expression on vascular endothelial cells, MVD, and mRNA transcription levels of vWF and endoglin were not significantly different between the two groups. However, expression of VEGF, VEGFR2, and pVEGFR2 was higher in epithelial tumors (P<0.01). Moreover, PI correlated with pVEGFR2 expression in only epithelial tumors (P<0.01, Rs=0.543). These results suggest that the activity of VEGF/VEGFR2 signaling in tumor cells is raised in epithelial tumors, and that this signaling pathway may be related to tumor cell proliferation in epithelial tumors.

Magnetic Resonance Imaging (MRI) Differential Diagnosis of Meningiomas Using ANOVA

This work explored the diagnostic value of different subtypes of meningiomas under T2WI low signal based on analysis of variance (ANOVA), and the expression differences of Ki67, VEGF, and P73 in different subtypes were analyzed. 67 patients with meningioma confirmed surgically and pathologically in hospital were selected as the research subjects, whose pathological classification occurs with obvious low signal on T2WI. First, the age distribution of the subjects and the distribution of different subtypes were counted. Then, ANOVA was adopted to analyze the MRI imaging signs of patients with different subtypes of meningioma. Finally, the differences of Ki67, VEGF, and P73 proteins and mRNA expression levels in different subtypes were detected via immunohistochemical assay and qPCR. The results showed that the proportion of patients with transitional meningioma was the most, which was 43.28%, while the proportion of patients with meningeal melanoma was the least, which was 7.46%. In patients with transitional meningioma, the MRI images showed mixed signals in different layers. Fibrous MRI images showed hyalinosis and calcification of collagen fibers in the tumor, with low T2WI signal. Sand-shape MRI images showed double low signals. MRI images of meningeal melanoma showed high signal on T1-weighted Imaging (T1WI) and low signal on T2WI. The protein expression and mRNA levels of Ki67 and P73 in transitional meningioma were evidently higher in contrast to those in fibrous meningioma (P < 0.05). The expression level of VEGF protein and mRNA in meningeal melanoma were notably higher in contrast to those in fibro meningioma (P < 0.05). It was revealed that the MRI images of the four subtypes of meningiomas under ANOVA-based T2WI low signal were quite different, and the expressions of Ki67, P73, and VEGF in different subtypes had significant differences. This work provided a reference basis for the preoperative diagnosis, treatment, and prognosis of meningiomas.

Phosphofructokinase-1 and fructose bisphosphatase-1 in canine liver and kidney

In healthy individuals, plasma glucose levels are maintained within a normal range. During fasting, endogenous glucose is released either through glycogenolysis or gluconeogenesis. Gluconeogenesis involves the formation of glucose-6-phosphate from a variety of precursors followed by its subsequent hydrolysis to glucose. Gluconeogenesis occurs in the liver and the kidney. In order to compare gluconeogenesis in canine liver and kidney, the activity and expression of the rate limiting enzymes that catalyze the fructose-6-phosphate and fructose 1,6-bisphosphate steps, namely, phosphofructokinase-1 (PFK-1) (glycolysis) and fructose bisphosphatase-1 (FBP-1) (gluconeogenesis), were examined. Healthy male and female beagle dogs aged 1–2 years were euthanized humanely, and samples of their liver and kidney were obtained for analysis. The levels of PFK-1 and FBP-1 in canine liver and kidney were assessed by enzymatic assays, Western blotting, and RT-qPCR. Enzyme assays showed that, in dogs, the kidney had higher specific activity of PFK-1 and FBP-1 than the liver. Western blotting and RT-qPCR data demonstrated that of the three different subunits (PFK-M, PFK-L, and PFK-P) the PFK-1 in canine liver mainly comprised PFK-L, whereas the PFK-1 in the canine kidney comprised all three subunits. As a result of these differences in the subunit composition of PFK-1, glucose metabolism might be regulated differently in the liver and kidney.

Phosphofructokinase-1 subunit composition and activity in the skeletal muscle, liver, and brain of dogs

Phosphofructokinase-1 (EC:2.7.1.11, PFK-1) catalyzes the phosphorylation of fructose 6-phosphate to fructose 1,6-bisphosphate using adenosine triphosphate and is a key regulatory enzyme of glycolysis. Mammalian PFK-1 isozymes are composed of three kinds of subunits (PFK-M, -L, and -P), with different properties. It has been suggested that the proportion of PFK-1 subunits in different organs is based on the organ energy metabolism. In this study, we analyzed the activity and subunit composition of canine PFK-1. We found that, in dogs, the skeletal muscle only has PFK-M, the liver mainly has PFK-L, and the brain expresses all of them. The knowledge of the composition of PFK-1 could provide useful information for determination of the differences in glycolysis in various organs of dogs.