Expression of blood hepatocyte-derived microRNA-122 in canine multicentric lymphoma with hepatic involvement

A review on microRNA detection and expression studies in dogs

MicroRNAs (miRNAs) are small non-coding RNAs that function by post-transcriptional regulation of gene expression. Their stability and abundance in tissue and body fluids makes them promising potential tools for both the diagnosis and prognosis of diseases and attractive therapeutic targets in humans and dogs. Studies of miRNA expression in normal and disease processes in dogs are scarce compared to studies published on miRNA expression in human disease. In this literature review, we identified 461 peer-reviewed papers from database searches using the terms "canine," "dog," "miRNA," and "microRNA"; we screened 244 for inclusion criteria and then included a total of 148 original research peer-reviewed publications relating to specific miRNA expression in canine samples. We found an overlap of miRNA expression changes between the four groups evaluated (normal processes, non-infectious and non-inflammatory conditions, infectious and/or inflammatory conditions, and neoplasia) in 39 miRNAs, 83 miRNAs in three of the four groups, 110 miRNAs in two of the three groups, where 158 miRNAs have only been reported in one of the groups. Additionally, the mechanism of action of these overlapping miRNAs varies depending on the disease process, elucidating a need for characterization of the mechanism of action of each miRNA in each disease process being evaluated. Herein we also draw attention to the lack of standardization of miRNA evaluation, consistency within a single evaluation method, and the need for standardized methods for a direct comparison.

Epigenetic Alterations in Canine Malignant Lymphoma: Future and Clinical Outcomes

Canine malignant lymphoma is a common neoplasia in dogs, and some studies have used dogs as a research model for molecular mechanisms of lymphomas in humans. In two species, chemotherapy is the treatment of choice, but the resistance to conventional anticancer drugs is frequent. The knowledge of molecular mechanisms of development and progression of neoplasia has expanded in recent years, and the underlying epigenetic mechanisms are increasingly well known. These studies open up new ways of discovering therapeutic biomarkers. Histone deacetylases and demethylase inhibitors could be a future treatment for canine lymphoma, and the use of microRNAs as diagnosis and prognosis biomarkers is getting closer. This review summarises the epigenetic mechanisms underlying canine lymphoma and their possible application as treatment and biomarkers, both prognostic and diagnostic.

MicroRNA-21 expression, serum tumor markers, and immunohistochemistry in canine mammary tumors

BACKGROUND

Canine mammary tumors (CMTs) are one of the most common malignancies in dogs and are associated with significant mortality. Serum tumor markers and non-coding microRNAs have gained widespread popularity in human oncology studies. The present study has two aims, first one is to investigate the miR-21 expression compared with changes in serum tumor markers (CEA and CA15-3) in CMT. The second aim is to detect the immunohistochemistry markers as vimentin, P63, and -SMA in CMT.

METHODS

This study enrolled 17 female dogs: 10 with mammary tumors and seven controls without tumors. Blood samples were collected to measure miR-21, CEA, and CA 15-3, and histological samples were prepared for histological grading and immunohistochemistry.

RESULTS

CA 15-3 was elevated in all animals, whereas CEA levels showed no change compared with controls. miR-21 was upregulated 12.84-fold in animals with CMT. The most frequently recorded CMT was the mixed type. Myoepithelial cells were identified by P63 immunoreactivity, but not SMA. High expression of miR-21 was observed with positive vimentin immunoreactivity, indicating the mesenchymal origin of the tumor cells.

CONCLUSION

The present study showed that miR-21 was elevated to a greater extent than CA 15-3 (12.84-fold vs. threefold). Tumors that was positive for vimentin immunoreactivity was also associated with an elevation in the levels of miR-21, showing that miR-21 is released from mesenchymal cells. These findings support the hypothesis that miR-21 may be a more sensitive, noninvasive indicator for CMT.

Hepatocyte-derived canine familiaris-microRNAs as serum biomarkers of hepatic steatosis or fibrosis as implicated in the pathogenesis of canine cholecystolithiasis

BACKGROUND

Hepatic cholesterol accumulation in small breed dogs is a leading risk factor for hepatic fatty changes, gallbladder hypomotility, and cholelith development, which, if not discovered early, could lead to life-threatening choledocholithiasis and acute pancreatitis.

OBJECTIVE

This study proposed to assess the use of hepatocyte-derived canine familiaris (cfa)-microRNAs (miRNA-122, -34a, and -21) as new diagnostic serum biomarkers of liver steatosis or fibrosis, for which both processes have been implicated in canine cholecystolithiasis.

METHODS

Forty client-owned dogs diagnosed with cholecystolithiasis and hepatic steatosis (C+HS) or fibrosis (C+HF) based on ultrasonographic, biochemical, and histopathologic findings, and 20 healthy dogs used as controls were included in the study. Serum cfa-miRNA expression was determined using a real-time polymerase chain reaction assay.

RESULTS

Serum cfa-miRNA-122 and -34a expression was significantly upregulated in the C+HS (P < .001) and C+HF (P < .01) groups compared with the control group and showed a positive correlation with alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), alkaline phosphatase (ALP), γ-glutamyl transferase (GGT), total cholesterol (TC), and triglycerides (TG) levels in the C+HS group. Cfa-miRNA-122 and -34a expression discriminated the diseased groups from the control group better than traditional serum-derived liver biomarkers, as evidenced by areas under the receiver operating characteristic (AUC-ROC) curve of 0.99 and 0.97 for cfa-miRNA-122 expression in the C+HS and C+HF groups, and 1.0 and 0.96 for cfa-miRNA-34a in the C+HS and C+HF groups, respectively. Cfa-miRNA-21 expression was upregulated only in the C+HF group compared with the C+HS (P < .01) and control (P < .001) groups and showed a positive correlation with serum ALT, AST, TBIL, ALP, and GGT and negative correlation with serum TC and TG levels. Cfa-miRNA-21 expression could also differentiate the C+HF group from the control and C+HS groups with a diagnostic performance superior to that of the conventional serum biochemical variables as evidenced by AUCs of 1.0 and 0.98, respectively.

CONCLUSIONS

Serum cfa-miRNA-122, -34a, and -21 expression was significantly upregulated in dogs with cholecystolithiasis with hepatic steatosis or fibrosis compared with control dogs. These miRNAs could serve as novel biomarkers for hepatic steatosis or fibrosis, which have been implicated in the pathogenesis of cholecystolithiasis.

Abramov P, M. Abdelhamid F. Clinical Characteristics, Serum Biochemical Changes, and Expression Profile of Serum Cfa-miRNAs in Dogs Confirmed to Have Congenital Portosystemic Shunts Accompanied by Liver Pathologies

Computed tomography angiography (CTA) and biochemical parameters cannot specify liver pathologies in dogs with congenital portosystemic shunts (CPSS) that are easily determined by invasive histopathology. This study aims to assess the possibility of using circulating serum canine familiaris (cfa) microRNAs (miRNAs) as novel non-invasive serum-based fingerprints for liver injuries associated with various morphologies of extrahepatic and intrahepatic portosystemic shunts (EHPSS and IHPSS). Data were obtained from 12 healthy dogs and 84 dogs confirmed to have EHPSS (splenocaval, splenophrenic, splenoazygos, right gastrocaval (RGC), right gastrocaval with caudal loop (RGC-CL)) and IHPSS (right divisional and left divisional) using CTA. Hepatic pathologies were determined by histopathology. Serum expression of miRNAs was assessed by real-time polymerase chain reaction. Based on the nature of liver injuries in each shunt type, cfa-miR-122 was significantly upregulated in all CPSS groups. Meanwhile, serums cfa-miR-34a and 21 were not significantly expressed in splenophrenic or splenoazygos groups, but they were extensively upregulated in splenocaval, RGC, RGC-CL groups and less frequently in right or left divisional groups. Also, serum cfa-miR126 was significantly upregulated in both IHPSS groups but less significantly expressed in RGC, RGC-CL, and splenocaval groups. Overall, estimated cfa-miRNAs could serve as novel biomarkers to mirror the histopathological and molecular events within the liver in each shunt type.