Expression of Apoptosis‐regulating Proteins Bcl‐2 and Bax in Lymph Node Aspirates from Dogs with Lymphoma

• Published in: Journal of veterinary internal medicine Vol. 30; no. 3; pp. 819 - 826
• Main Authors: Meichner, K., Fogle, J.E., English, L., Suter, S.E.
• Format: Journal Article
• Language: English
• Published: United States John Wiley and Sons Inc 01.05.2016; Wiley
• Subjects: Animals; Antineoplastic Agents - administration & dosage; Antineoplastic Agents - therapeutic use; Apoptosis; bcl-2-Associated X Protein - genetics; bcl-2-Associated X Protein - metabolism; Canine; Case-Control Studies; Dog Diseases - drug therapy; Dog Diseases - pathology; Dogs; Female; Flow cytometry; Flow Cytometry - veterinary; Gene Expression Regulation, Neoplastic; Lymph Nodes - metabolism; Lymph Nodes - pathology; Lymphoma, B-Cell - drug therapy; Lymphoma, B-Cell - pathology; Lymphoma, B-Cell - veterinary; Lymphoma, T-Cell - drug therapy; Lymphoma, T-Cell - pathology; Lymphoma, T-Cell - veterinary; Lymphosarcoma; Male; Programmed cell death; Prospective Studies; Proto-Oncogene Proteins c-bcl-2 - genetics; Proto-Oncogene Proteins c-bcl-2 - metabolism; SMALL ANIMAL; Systole; Treatment Outcome; Flow cytometry; Programmed cell death; Lymphosarcoma; Canine
• ISSN: 0891-6640; 1939-1676
• DOI: 10.1111/jvim.13937

Background Dysregulated apoptosis is a hallmark of tumorigenesis, and is also involved in resistance to cytotoxic treatment, and might be relevant in lymphoma in dogs. Hypothesis/Objectives That Bcl‐2/Bax expression patterns differ between lymphoma immunophenotypes, and that Bcl‐2/Bax ratio is correlated with prognosis. Animals Fifty‐five client‐owned dogs with multicentric lymphoma and 5 healthy dogs. Methods Prospective, case–control study. We compared 3 methods (flow cytometry, qRT‐PCR, Western blot) for Bcl‐2 and Bax quantification in a subset of dogs. The effect of time on Bcl‐2/Bax ratios measured by flow cytometry was assessed in lymphoma cell lines. Immunophenotype and Bcl‐2/Bax expression by flow cytometry were determined in LN aspirates from all dogs with multicentric lymphoma compared to healthy dogs. Progression‐free survival (PFS) was retrospectively evaluated in a group of dogs all receiving similar treatment. Results Bcl‐2/Bax ratios remain consistent for at least 5 days after sample collection. Bcl‐2/Bax ratio was higher in dogs with T‐cell lymphoma (TCL; median 0.97, range 0.37–1.36) compared to B‐cell lymphoma (BCL; median 0.36, range 0.07–1.45) (P < .0001) and normal dogs (median 0.36, range 0.21–0.48) (P = .0006), respectively. Dogs with Bcl‐2/Bax ratios higher than the median of the group experienced a median PFS of 101 days and dogs with ratios equal and lower than the median had PFS of 130 days (P = .19). Conclusions and clinical importance Higher intrinsic resistance to apoptosis following cytotoxic treatment might contribute to the less favorable prognosis associated with multicentric TCL in dogs. Whether Bcl‐2/Bax will be helpful to identify canine BCL and TCL with more aggressive and more indolent behavior, respectively, should be evaluated in larger prospective clinical studies.