OBJECTIVETo explore the expression of multidrug resistance gene 1 ( MDR1), glutathione-S-transferases-pi (GST-pi) in osteosarcoma and soft tissue sarcoma tissues from 34 patients and their correlation with chemotherapy resistance.

METHODSMDR1 and GST-pi expressions were analyzed by real-time fluorescence quantitative polymerase chain reaction (FQ-PCR) and flow cytometry (FCM) at mRNA and protein levels, respectively. Chemotherapy sensitivity on adriamycin, cisplatinum, fluorouracil, mitomycin C, dacarbazine, vincristine, methotrexate in tumor tissues were detected by MTT assay.

RESULTSThe nonsensitive rates on adriamycin, cisplatinum, fluorouracil, mitomycin C, dacarbazine, vincristine, methotrexate in tumor tissues were 41.18%, 17.7%, 47.1%, 50.0%, 76.5%, 61.8% and 52.9%, respectively. The expression of P-glycoprotein (P-gp) and GST-pi in tumor tissues was 1.54 and 2.58 (relative fluorescence intensity). Chi2 analysis showed that there was a positive correlation between P-gp expression and drug resistance on ADM, GST-pi expression and resistance on ADM, DDP and MMC (P < 0.05). There was not seen obvious correlation between expression of MDR1, GST-pi and age, gender, pathological type, tumor size in osteosarcoma and soft tissue sarcoma patients (P > 0.05). The expression of GST-pi was increased in patients receiving preoperative chemotherapy. The rate of postoperative recurrence was higher in patients with higher GST-pi expression level than those with lower GST-pi expression level before operation (P < 0.05).

CONCLUSIONIndividual differences exist in chemotherapy sensitivity and expression of MDR1 and GST-pi in osteosarcoma and soft tissue sarcomas patients. Chemotherapy can induce up-regulation of GST-pi protein expression. Primary high expression of GST-pi is the main mechanism of resistance of osteosarcoma and soft tissue sarcomas to chemotherapy and is related to poor prognosis.

ATP-Binding Cassette, Sub-Family B, Member 1 ; biosynthesis ; genetics ; Adolescent ; Adult ; Aged ; Antineoplastic Combined Chemotherapy Protocols ; therapeutic use ; Bone Neoplasms ; drug therapy ; genetics ; metabolism ; Child ; Cisplatin ; therapeutic use ; Doxorubicin ; therapeutic use ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Female ; Flow Cytometry ; Follow-Up Studies ; Glutathione S-Transferase pi ; biosynthesis ; genetics ; Humans ; Male ; Middle Aged ; Mitolactol ; therapeutic use ; Mitomycins ; therapeutic use ; Osteosarcoma ; drug therapy ; genetics ; metabolism ; Prognosis ; RNA, Messenger ; biosynthesis ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; methods ; Sarcoma ; drug therapy ; genetics ; metabolism