P-Glycoprotein Activity at Diagnosis Does Not Predict Therapy Outcome and Survival in Canine B-Cell Lymphoma.

Various mechanisms are known to be involved in the development of multidrug resistance during cancer treatment. P-glycoprotein (P-gp) decreases the intracellular concentrations of cytotoxic drugs by an energy-dependent efflux mechanism. The aim of this study was to investigate the predictive value of P-gp function based on the evaluation of P-gp activity in tumor cells obtained from canine B-cell lymphoma patients at diagnosis.

Celecoxib Prevents Doxorubicin-Induced Multidrug Resistance in Canine and Mouse Lymphoma Cell Lines.

Background: Treatment of malignancies is still a major challenge in human and canine cancer, mostly due to the emergence of multidrug resistance (MDR). One of the main contributors of MDR is the overexpression P-glycoprotein (Pgp), which recognizes and extrudes various chemotherapeutics from cancer cells.

Methods: To study mechanisms underlying the development of drug resistance, we established an in vitro treatment protocol to rapidly induce Pgp-mediated MDR in cancer cells.

Evaluation of Pgp (MDR1) immunohistochemistry in canine lymphoma - prognostic and clinical aspects.

Permeability glycoprotein (P-glycoprotein, Pgp) immunohistochemistry (IHC) was evaluated in dogs with multicentric lymphoma treated with cyclophosphamide- doxorubicin-vincristine-prednisolone with or without L-Asparaginase. Lymph nodes of 33 untreated dogs were immunophenotyped: Ki67% and Pgp analyses (with anti-Pgp, monoclonal mouse C494 clone) were performed. Pgp positivity rate and intensity were determined microscopically (by manual counting done by two blinded authors in two parallel specimens).