Identification of candidate biomarkers of therapeutic response to docetaxel by proteomic profiling.
Docetaxel chemotherapy improves symptoms and survival in men with metastatic hormone-refractory prostate cancer (HRPC). However, approximately 50% of patients do not respond to Docetaxel and are exposed to significant toxicity without direct benefit. This study aimed to identify novel therapeutic targets and predictive biomarkers of Docetaxel resistance in HRPC. We used iTRAQ-mass spectrometry analysis to identify proteins associated with the development of Docetaxel resistance using Docetaxel-sensitive PC3 cells and Docetaxel-resistant PC3-Rx cells developed by Docetaxel dose escalation. Functional validation experiments were performed using recombinant protein treatment and siRNA knockdown experiments. Serum/plasma levels of the targets in patient samples were measured by ELISA. The IC(50) for Docetaxel in the PC3-Rx cells was 13-fold greater than the parent PC-3 cell line (P = 0.004). Protein profiling identified MIC-1 and AGR2 as respectively up-regulated and down-regulated in Docetaxel-resistant cells. PC-3 cells treated with recombinant MIC-1 also became resistant to Docetaxel (P = 0.03). Conversely, treating PC3-Rx cells with MIC-1 siRNA restored sensitivity to Docetaxel (P = 0.02). Knockdown of AGR2 expression in PC3 cells resulted in Docetaxel resistance (P = 0.007). Furthermore, increased serum/plasma levels of MIC-1 after cycle one of chemotherapy were associated with progression of the cancer (P = 0.006) and shorter survival after treatment (P = 0.002). These results suggest that both AGR2 and MIC-1 play a role in Docetaxel resistance in HRPC. In addition, an increase in serum/plasma MIC-1 level after cycle one of Docetaxel may be an indication to abandon further treatment. Further investigation of MIC-1 as a biomarker and therapeutic target for Docetaxel resistance in HRPC is warranted.
Zhao
Liangli
L
Cancer Research Program, Garvan Institute of Medical Research, Sydney, Australia.
Lee
Brian Y
BY
Brown
David A
DA
Molloy
Mark P
MP
Marx
Gavin M
GM
Pavlakis
Nick
N
Boyer
Michael J
MJ
Stockler
Martin R
MR
Kaplan
Warren
W
Breit
Samuel N
SN
Sutherland
Robert L
RL
Henshall
Susan M
SM
Horvath
Lisa G
LG
D000970:Antineoplastic Agents / Q000494:pharmacology*; D014408:Biomarkers, Tumor / Q000096:biosynthesis / Q000097:blood*; D045744:Cell Line, Tumor; D000077143:Docetaxel; D019008:Drug Resistance, Neoplasm; D055436:Growth Differentiation Factor 15 / Q000096:biosynthesis / Q000097:blood / Q000235:genetics / Q000494:pharmacology; D006801:Humans; D008297:Male; D009088:Mucoproteins; D015513:Oncogene Proteins; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood* / Q000188:drug therapy* / Q000235:genetics; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D034741:RNA, Small Interfering / Q000235:genetics; D011994:Recombinant Proteins / Q000494:pharmacology; D043823:Taxoids / Q000494:pharmacology*; D014162:Transfection
C502296:AGR2 protein, human; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; C526140:GDF15 protein, human; D055436:Growth Differentiation Factor 15; D009088:Mucoproteins; D015513:Oncogene Proteins; D011506:Proteins; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D043823:Taxoids; D000077143:Docetaxel; D017430:Prostate-Specific Antigen