Canine mammary tumors (CMTs), one of the most common malignant neoplasms in female dogs, currently lack effective chemotherapeutic options beyond surgical treatment. Conjugated linoleic acid (CLA), particularly the cis-9, trans-11 CLA (c9, t11-CLA) isomer, has demonstrated anticancer potential in human studies; however, its specific mechanisms in CMTs remain largely unexplored. This study investigated the antitumor effects of c9, t11-CLA on the CMT cell line CMT-U27, focusing on apoptosis regulation and oxidative stress modulation, thereby providing the theoretical basis for developing novel anti-tumor therapies. Following treatment of the CMT-U27 cells with various concentrations of c9, t11-CLA, CCK-8 assays revealed a concentration-dependent increase in apoptosis. Quantitative RT-qPCR and western blot analyses were performed to assess the 120μM, the expression of the anti-apoptotic proteins (Bcl-2 and Bcl-XL) was significantly decreased (P<0.05), while the expression of proapoptotic proteins (Bax and Bad) increased (P<0.05). Additionally, catalase expression was reduced (P<0.05), the malondialdehyde content was increased, and superoxide dismutase activity was decreased. In summary, this study demonstrates that c9, t11-CLA treatment significantly inhibits the proliferation of CMT-U27 cells, potentially through modulation of Bcl-2 family protein expression, activation of peroxisome proliferator-activated receptor gamma (PPARγ), and disruption of the oxidative homeostasis.

To Cite This Article: Ren y, Wang Z, Li M and Shen X 2025. Cis-9, Trans-11 conjugated linoleic acid promotes apoptosis, restores oxidative homeostasis, and inhibits the proliferation of canine mammary tumor cells. Pak Vet J, 45(2): 807-815. http://dx.doi.org/10.29261/pakvetj/2025.194