ABSTRACT
The clinical observation of the multidrug resistance (MDR) phenotype is often associated with overexpression of the mdrl gene, in particular with respect to ovarian cancer. However, until now the mdrl-inducing potential of commonly used antineoplastics has been only incompletely explored. We performed short-term cultures of six ovarian cancer cell lines (MZOV4, EF027, SKOV3, OAW42, OTN14, MZOV20) exposed to either blank medium or cisplatin, doxorubicin or paclitaxel at concentrations related to the clinically achievable plasma peak concentration. A highly specific quantitative real-time RT-PCR was used to detect the Mdr1 transcripts. Mdrl mRNA contents were calibrated in relation to coamplified GAPDH mRNA. Mdrl mRNA was detectable in each cell line. In 13 out of 18 assays (72%) the specific anticancer drug being tested induced mdr1 transcription. No decrease in mdr1 mRNA concentration was observed. Our data suggest that mdr1 induction by antineoplastics is one of the reasons for failure of ovarian cancer therapy but may vary individually.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , Antineoplastic Agents/pharmacology , Drug Resistance, Multiple/genetics , Drug Resistance, Neoplasm/genetics , Gene Expression Regulation, Neoplastic/drug effects , Ovarian Neoplasms/genetics , Antineoplastic Agents, Phytogenic/pharmacology , Cisplatin/pharmacology , DNA Primers/chemistry , Doxorubicin/pharmacology , Drug Screening Assays, Antitumor , Female , Humans , Ovarian Neoplasms/metabolism , Paclitaxel/pharmacology , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Transcription, Genetic/drug effects , Tumor Cells, Cultured/drug effectsABSTRACT
BACKGROUND: Development of resistance to anticancer drugs is a major concern in clinical oncology and might be particularly involved in the secondary treatment failure frequently seen in ovarian cancer. Clinical observation of the multidrug resistance (MDR) phenotype is often associated with overexpression of the mdr1-gene. However, until now the mdr1-inducing potential of commonly used antineoplastics has been only incompletely explored. MATERIALS AND METHODS: We perfomed short-term cultures of 7 established ovarian cancer cell lines exposed to either blank medium or one of three single anticancer drugs (cisplatin, doxorubicin, paclitaxel) at concentrations related to the clinically achievable plasma peak concentration. Mdr1-transcripts were detected using the highly specific quantitative real time RT-PCR. To calibrate each approach, mdr1-mRNA content was calculated in relation to co-amplified GAPDH-mRNA. RESULTS: Mdr1-mRNA was detectable in each cell line. In 13 assays (62%) the specific anticancer drug being tested induced mdr1-transcription. No decrease in mdr1-mRNA concentration was observed. The method described here is easy to perform and could be of striking value in predicting the development of tumor chemoresistance. CONCLUSION: Our data indicate that mdr1-induction by antineoplastics is one of the reasons for failure of ovarian cancer therapy but may vary from one individual to another.
