Role of BCRP as a biomarker for predicting resistance to 5-fluorouracil in breast cancer.
OBJECTIVE
Chemotherapy is not only important but also necessary for the patient of breast cancer. Breast cancer resistance protein (BCRP), an atypical drug efflux pump, mediates multidrug resistance in breast cancer. The aim of this study is to search new substrate of BCRP. The result will guide the drug selection of chemotherapy in BCRP-positive breast cancer.


METHODS
PA317/Tet-on/TRE-BCRP cell induced with doxycycline was used to screen the possible substrates of BCRP by MTT assay. The suspicious substrate [5-fluorouracil (5-Fu)] was further confirmed in PA317 and breast cancer cell MCF-7 by HLCP, apoptosis assay (staining and FACS) and RNAi technique.


RESULTS
Mitoxantrone, 5-Fu, adriamycin, Methotrexate, Pirarubicin, and Etoposide were identified as substrates of BCRP. However, Paclitaxel, Vincristine, Vindesine, Mitomycin C, and cisplatin were not mediated by BCRP. 5-Fu was identified as substrate of BCRP for the first time. The further study showed that the intracellular retention dose of 5-Fu and the 5-Fu induced cellular apoptosis all decreased when BCRP highly expressed. Furthermore, 5-Fu accumulation and 5-Fu induced DNA damage increased when BCRP was silenced by RNAi in breast cancer cells.


CONCLUSIONS
5-Fluorouracil may be a specific substrate which can be bound by BCRP. BCRP can predict the sensitivity of breast cancer to 5-Fu. And BCRP-targeted therapy will reverse the resistance of breast cancer to 5-Fu.
Yuan
Jianhui
J
Cancer Research Institute, Xiangya School of Medicine, Central South University, Xiangya Road #110, 410078, Changsha, Hunan, People's Republic of China.
Lv
Hui
H
Peng
Bo
B
Wang
Chengkun
C
Yu
Yanhui
Y
He
Zhimin
Z
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D014408:Biomarkers, Tumor / Q000096:biosynthesis*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D020552:Comet Assay; D019008:Drug Resistance, Neoplasm; D005260:Female; D005434:Flow Cytometry; D005472:Fluorouracil / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D011237:Predictive Value of Tests
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000964:Antimetabolites, Antineoplastic; D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D005472:Fluorouracil