Quantitative pharmacoproteomics investigation of anti-cancer drugs in mouse. Development and optimisation of proteomics workflows for evaluating the effect of anti-cancer drugs on mouse liver

Abstract

Minimizing anti-cancer drug toxicity is a major challenge for the pharmaceutical industry. Toxicity is most frequently due to either the direct interaction of the drug on previously unidentified targets or its conversion to metabolites by drug metabolizing enzymes (e.g. CYP450 enzymes) that cause cellular, tissue or organ damage. Pharmacoproteomics is beginning to take a central role in studying changes in protein expression corresponding to drug administration, the results of which, inform about the mode of action, toxicity, and resistance in pre-clinical and clinical stages of drug development. The main aim of this research is to apply comparative proteomics studies on livers from male and female mice xenograft models treated with major anti-cancer drugs (5-flourouracil, paclitaxel, cisplatin, and doxorubicin) and CYP inducer, TCPOBOP, to investigate their effect on protein expression profiles (proteome). Within this thesis, an attention is paid to optimise a highly validated proteomics workflow for biomarker identification. Proteins were extracted from liver microsomes of mice treated in two separate sets; Set A – male (5-fluoruracil, doxorubicin, cisplatin and untreated) or Set B – female (5-fluoruracil, paclitaxel, TCPOBOP and untreated) using cryo-pulverization and sonication method. The extracts were digested with trypsin ii and the resulting peptides labelled with 4-plex iTRAQ reagents. The labelled peptides were subjected for separation in two-dimensions by iso-electric focusing (IEF) and RP-HPLC techniques before analysis by mass spectrometry and database searching for protein identification. Set A and Set B resulted in identification and quantification of 1146 and 1743 proteins, respectively. Moreover, Set A and Set B recovered 26 and 34 cytochrome P450 isoforms, respectively. The microsomal changes after drug treatments were quite similar. However, more changes were observed in the male set. Up-regulation of MUPs showed the greatest distinction in the protein expression patterns in the treated samples comparing to the untreated controls. In Set A, 5-fluoruracil and cisplatin increased the expression of three isoforms (MUP1, 2, and 6), whereas doxorubicin has increased the expression of four isoforms (MUP1, 2, 3, and 6). On the other side, only TCPOBOP in Set B has increased the expression of two isoforms (MUP1 and 6). Our findings showed that the expression of MUP, normally involved in binding and excretion of pheromones, have drug- and sex-specific differences. The mechanism and significance of MUP up-regulation are ambiguous. Therefore, the impact of each therapeutic agent on MUP and xenobiotic enzymes will be discussed.