The PI3K/Akt/PTEN axis is one of the most important signaling pathways in tumorigenesis. Recently, mutation of PIK3CA has been highlighted due to the similarities of mutational hotspots in both dogs and humans. PIK3CA H1047R (c.3140A > G) has been discovered as the most common mutational hot spot in canine mammary tumor in recent studies, while the feature of PIK3CA-mutated canine mammary tumor is obscure. Methods: A total of 83 mammary samples classified as normal (n = 13), adenoma (n = 25), low-grade carcinoma (n = 21), and high-grade carcinoma (n = 24) were included in this study. Genomic DNA from each sample was extracted, amplified by conventional PCR, and analyzed through Sanger sequencing. Analysis for the expression of PIK3CA, Akt, p-Akt, and PTEN was performed by immunohistochemistry, and of Akt2 by RNA in situ hybridization. Results: PIK3CA H1047R mutation was detected in 14.3% (10/70) of tumor samples. Dysregulation of p-Akt, Akt2, and PTEN was observed in mammary tumor samples, but only PTEN dysregulation was associated with PIK3CA H1047R mutation. Conclusions: The present study showed that dysregulation of components in the PI3K/Akt/PTEN pathway is a feature of canine mammary tumors, but this dysregulation is not directly correlated to the PIK3CA H1047R mutation except for PTEN expression.

Feline cancer is increasingly recognized as a major cause of mortality, yet data on tumor prevalence and behavior in cats, particularly in non-Western regions, remain limited. This study analyzed a decade of feline tumor data in Korea from 2012 to 2022, focusing on age, breed, and anatomical location as predictors of malignancy. Data were collected from 683 cats, with regression analysis applied to determine significant associations. Older cats exhibited a markedly higher risk of malignancy, particularly in mast cell and mammary tumors. Tumors in the mammary gland and alimentary tract had malignancy rates exceeding 90%, underscoring the need for early detection in these regions. Interestingly, squamous cell carcinoma was rare in the skin, in stark contrast to Western studies, likely reflecting differences in environmental exposure. While breed was not a statistically significant predictor, certain breeds, including Persians and Russian Blues, showed a higher frequency of malignancy. These findings highlight the importance of regional tumor research in cats and the need for larger, multicenter datasets that incorporate environmental, genetic, and lifestyle factors. Understanding these influences will help refine veterinary care and improve cancer treatment outcomes in feline populations.

Domestic dogs (Canis lupus familiaris) serve as valuable translational models for human cancer research due to their biological similarities. Canine mammary tumors (CMTs), frequently diagnosed in female dogs, share various characteristics with human breast cancers. This study investigates the PIK3CA (H1047R) mutation in CMTs using droplet digital PCR (ddPCR) and explores the potential of liquid biopsy for non-invasive detection. We analyzed 80 formalin-fixed, paraffin-embedded (FFPE) CMT tissue samples and compared ddPCR results with next-generation sequencing (NGS) data, achieving high concordance. Plasma and serum samples were also assessed for mutation concordance with tissue results. Our findings indicate a higher frequency of the PIK3CA (H1047R) mutations in benign and grade I malignant CMTs compared to more aggressive malignancies. The ddPCR assay demonstrated high sensitivity and specificity, with plasma testing showing 78.6% sensitivity and 87.5% specificity, and serum testing showing 66.7% sensitivity and 90.0% specificity. These results highlight the viability of liquid biopsy as a minimally invasive method for monitoring PIK3CA mutations in canine patients. The study suggests that liquid biopsy techniques hold significant promise for improving the early detection and monitoring of canine cancers, warranting further research to refine these methods and explore their applications in canine cancer diagnostics and treatment.

Ju JH, et al. J Vet Sci. 2019 Mar;20(2):e11. https://doi.org/10.4142/jvs.2019.20.e11

Song DW, et al. J Vet Sci. 2021 Sep;22:e77. https://doi.org/10.4142/jvs.2021.22.e77

Kim SH, et al. J Vet Sci. 2021 Jul;22(5):e61. https://doi.org/10.4142/jvs.2021.22.e61