ABSTRACT
Ovarian cancer is currently the most lethal gynecologic malignancy in Europe and the US. Platin analogues and paclitaxel demonstrate high remission rates, but unfortunately the efficacy of cytostatic agents is limited by the development of multidrug resistance (mdr). Clinical paclitaxel resistance is often associated with mdr1 overexpression. In a recent study, we introduced a highly specific quantitative real-time reverse transcriptase polymerase chain reaction for the quantification of mdr1 transcripts. In the present study, we demonstrate that primary tumor cells from patients with recurrent ovarian cancer overexpress mdr1. To evaluate mdr1 expression, we collected tumor cells from 77 ovarian cancer patients (13 chemotherapy-naive ovarian cancer, 64 recurrent ovarian cancer). Cancer cells were aspirated from 49 solid specimens (63%) and 28 ascitic fluids (37%). Subsequently, cancer cells were exposed in 221 short-term cultures either to blank medium (control) or to a single anticancer drug, cisplatin, doxorubicin or paclitaxel. The drug concentrations applied referred to clinical relevant doses. mdr1 mRNA expression was significantly higher in specimens from recurrent ovarian cancer incubated in paclitaxel than in specimens from chemotherapy-naive ovarian cancer. No significant differences were detectable between the mean value of mdr1 mRNA expression in tumor specimens from recurrent ovarian cancer incubated in cisplatin or doxorubicin. Differences within the untreated patients group were also not statistically significant. The result of this study confirms clinical observations, as well as in-vitro studies based on tumor cell lines, that paclitaxel resistance is correlated with mdr1 overexpression.
Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics , Antineoplastic Agents/pharmacology , Neoplasm Recurrence, Local/drug therapy , Ovarian Neoplasms/drug therapy , Adult , Aged , Cell Line, Tumor , Cisplatin/pharmacology , Doxorubicin/pharmacology , Female , Humans , Middle Aged , Neoplasm Recurrence, Local/genetics , Ovarian Neoplasms/genetics , Paclitaxel/pharmacology , RNA, Messenger/analysisABSTRACT
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.
