Extracellular cyclic adenosine monophosphate-dependent protein kinase A autoantibody and C-reactive protein as serum biomarkers for diagnosis of cancer in dogs

Protein kinase A, a cyclic adenosine monophosphate (AMP)‐dependent enzyme, normally exists within mammalian cells; however, in cancer cells, it can leak out and be found in the serum. Extracellular cyclic AMP‐dependent protein kinase A (ECPKA) has been determined to increase in the serum of cancer‐bearing dogs. However, there have been no reports in the veterinary literature on serum ECPKA autoantibody (ECPKA‐Ab) expression in dogs with cancer. The aim of this study was to evaluate ECPKA‐Ab and C‐reactive protein (CRP) as serum biomarkers for cancer in dogs. ECPKA‐Ab and CRP levels were detected by an enzyme‐linked immunosorbent assay in serum samples from dogs with malignant tumours (n = 167), benign tumours (n = 42), or non‐tumour disease (n = 155) and from healthy control dogs (n = 123). ECPKA‐Ab and CRP levels were significantly higher in the dogs with malignant tumours than in those with benign tumours or non‐tumour diseases, as well as in the healthy controls (P < 0.001, Kruskal‐Wallis test). There was a significant positive correlation between the neoplastic index, which was developed using ECPKA‐Ab and CRP levels, and the presence of cancer in dogs (P < 0.001); the area under the receiver‐operating characteristic curve was estimated to be >0.85 (P < 0.001). In conclusion, ECPKA‐Ab is a potential serum biomarker for a broad spectrum of cancers. Combined measurement of CRP and ECPKA‐Ab levels in serum improves the sensitivity and accuracy of a diagnosis of cancer in dogs.

Characteristics of extracellular cyclic AMP-dependent protein kinase as a biomarker of cancer in dogs

OBJECTIVE

Early and proper diagnosis of cancer is the most critical factor for the survival and treatment of veterinary cancer patients. In this study, we evaluated extracellular cyclic AMP-dependent protein kinase A (ECPKA) level in serum as a useful cancer biomarker in dogs.

METHODS

ECPKA levels were detected in sera from dogs with cancers (n = 48), benign tumours (n = 18), and non-tumour diseases (n = 102) as well as healthy control dogs (n = 54) utilizing enzyme-linked immunosorbent assay (ELISA).

RESULTS

Sera from dogs bearing various types of cancer exhibited markedly increased levels of ECPKA by up to 7.1-, 8.8-, and 10.9-fold compared with those from dogs harbouring benign tumours, dogs with non-tumour diseases, and healthy control dogs, respectively (P < .0001). In addition, serum ECPKA level did not show statistically significant correlation with gender, breed, or age of dogs or their non-cancerous disease conditions.

CONCLUSION

Our data strongly propose that detection of serum ECPKA level is a potential and specific diagnostic tool for cancer in dogs.