Transcriptome analysis of ABCB1, ABCG2 and the BCL2/BAX ratio in refractory and relapsed canine lymphomas under treatment and rescue protocol

Abstract

The main problems that cause unresponsiveness to an anti-neoplastic drug are the overexpression of drug resistant and anti-apoptotic proteins in tumor cells. In a rescue protocol we evaluated the ability of toceranib phosphate concurrent with lomustine (CCNU) or L-asparaginase and vincristine to decrease drug resistant and apoptotic proteins in relapsed and refractory canine lymphomas. The peripheral blood samples were collected before and after the rescue treatment from fourteen dogs that were refractory to cyclophosphamide-vincristine-prednisolone (COP) or COP-doxorubicin (CHOP) treatment and had recurrent multicentric lymphoma. The mRNA expression level of ABCB1, ABCG2, Bcl2 and Bax were determined by quantitative real-time PCR. The fold-change in ABCB1, ABCG2, Bcl2 and Bax mRNA levels were analyzed in correlation with the progression-free survival (PFS). After the rescue treatment, the ABCB1 and ABCG2 mRNA expression levels were 1.57- and 1.85-fold lower (p = 0.4 and p = 0.87), respectively, compared to pre-treatment. Bcl2/Bax ratio was numerically but not significantly decreased 1.02-fold (p = 0.74). The overall response rate of this protocol was 50% with a median PFS of 79 days (range 14-207 days). The low medians of relative expression levels of ABCB1, ABCG2 and Bcl2/Bax ratio group did not correlate with the clinical outcomes when compared to the high medians of relative expression levels, and likewise with the clinical stage, immunophenotype, histological grade and sub-stage. Therefore, the administration of a rescue drug with toceranib phosphate might be beneficial in refractory and relapsed canine lymphoma.

Immunophenotype, Molecular Diagnosis, Minimal Residual Disease, and Multidrug Resistance Protein Expression in Modified Cop, Modified Chop and Rescue Protocols of Treated Canine Lymphomas

“…However, CD79a staining gave a negative result in four cases of B-cell lymphoma (Dog No. 1,2,20,42) and a positive result in four cases of T-cell lymphoma (Dog No. 33,35,36,38) as shown in Table 1.…”

“…(D) The hPARR analysis showed monoclonal IgH genes from WBC samples in week 0 and after week 4 to 13 a diffused pattern of both IgH and TCRγ genes was evident. L = ExcelBand 100bp ladder; 1 = Cµ gene (130 bp); 2,5,8,11,14, 17, 20, 23 = IgH genes (120 bp);3,6,9,12,15, 18, 21, 24 = TCRγ-1 genes (90 bp);4,7,10,13,16, 19, 22,[5][6][7][11][12][13][17][18][19]25 = heteroduplex analysis; 26 = B-cell lymphoma; 27 = T-cell lymphoma; 28= negative control.…”