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The role of topotecan for extending the platinum-free interval in recurrent ovarian cancer: an in vitro model.
Gynecol Oncol. 2004 Jul; 94(1):67-73.GO

Abstract

OBJECTIVE

Topotecan, a novel topoisomerase-I inhibitor, is an active agent of second-line chemotherapy for extending the platinum-free interval (PFI) and improving the chances of a response to platinum in recurrent ovarian cancer patients. The aim of this study was to understand the molecular mechanism of topotecan-based second-line chemotherapy through an in vitro cell culture model and to gain clinical insight into sequencing issues for second-line treatment with novel agents versus retreatment with platinum.

STUDY DESIGN

The human ovarian cancer cell line A2780 and the cisplatin resistance cell line A2780-CR were separately seeded in 6-well cell culture plates and then exposed to multiple concentrations of cisplatin plus paclitaxel or topotecan for 7 days. Surviving cells were recovered and cultured in drug-free media for 3 weeks and then replated in a 96-well microtiter plate. The LD(50) for these cells was determined by a cytotoxic MTT assay after exposure to multiple clinically relevant concentrations of cisplatin or topotecan. Surviving cells were cultured in drug-free media for an additional 4 weeks at which time the LD(50) was reassessed for each cell population by a second MTT assay. Using RT-PCR and Northern blot hybridization to measure mRNA expression, the molecular profile of these cells in terms of resistance was evaluated for the multidrug-resistant gene (MDR-1), multidrug-resistant protein (MRP), Topoisomerase-I, and beta-Actin.

RESULTS

The LD(50) to cisplatin was unchanged in A2780-CR cells treated by topotecan. Those A2780-CR cells originally exposed to higher concentrations of cisplatin became more resistant to cisplatin in the MTT assays, while those A2780-CR cell lines treated with a combination of lower cisplatin concentrations and paclitaxel became more sensitive to cisplatin in the MTT assay (P < 0.01). The second MTT assay demonstrated that the LD(50) for cisplatin in every cell line decreased significantly after a 4-week drug-free interval (P < 0.01). There was no difference in the mRNA expression for MRP or topoisomerase-I regardless of cell line, or type or concentration of chemotherapeutic exposure. The mRNA for MDR-1 was uniquely overexpressed in the cisplatin-resistant cell line A2780-CR9 initially treated with low doses of cisplatin and paclitaxel, but was not amplified in A2780 (P < 0.01).

CONCLUSIONS

The acquired resistance to cisplatin in A2780 is potentially due to P-glycoprotein-mediated multidrug resistance. This acquired resistance to cisplatin is an unstable phenotype in that some cell populations become sensitive after a drug-free interval and topotecan treatment. This reversal of resistance, however, does not appear to be simply due to loss of MDR-1 expression. While in vivo confirmation is required, agents with novel mechanisms of action offer a strategy to extend the platinum-free interval and thereby improve survival in patients with recurrent ovarian cancer.

Authors+Show Affiliations

Department of Obstetrics and Gynecology, Washington University School of Medicine, St Louis, MO 63110, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

15262121

Citation

Horowitz, Neil S., et al. "The Role of Topotecan for Extending the Platinum-free Interval in Recurrent Ovarian Cancer: an in Vitro Model." Gynecologic Oncology, vol. 94, no. 1, 2004, pp. 67-73.
Horowitz NS, Hua J, Gibb RK, et al. The role of topotecan for extending the platinum-free interval in recurrent ovarian cancer: an in vitro model. Gynecol Oncol. 2004;94(1):67-73.
Horowitz, N. S., Hua, J., Gibb, R. K., Mutch, D. G., & Herzog, T. J. (2004). The role of topotecan for extending the platinum-free interval in recurrent ovarian cancer: an in vitro model. Gynecologic Oncology, 94(1), 67-73.
Horowitz NS, et al. The Role of Topotecan for Extending the Platinum-free Interval in Recurrent Ovarian Cancer: an in Vitro Model. Gynecol Oncol. 2004;94(1):67-73. PubMed PMID: 15262121.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The role of topotecan for extending the platinum-free interval in recurrent ovarian cancer: an in vitro model. AU - Horowitz,Neil S, AU - Hua,Jun, AU - Gibb,Randall K, AU - Mutch,David G, AU - Herzog,Thomas J, PY - 2003/09/25/received PY - 2004/7/21/pubmed PY - 2004/8/18/medline PY - 2004/7/21/entrez SP - 67 EP - 73 JF - Gynecologic oncology JO - Gynecol Oncol VL - 94 IS - 1 N2 - OBJECTIVE: Topotecan, a novel topoisomerase-I inhibitor, is an active agent of second-line chemotherapy for extending the platinum-free interval (PFI) and improving the chances of a response to platinum in recurrent ovarian cancer patients. The aim of this study was to understand the molecular mechanism of topotecan-based second-line chemotherapy through an in vitro cell culture model and to gain clinical insight into sequencing issues for second-line treatment with novel agents versus retreatment with platinum. STUDY DESIGN: The human ovarian cancer cell line A2780 and the cisplatin resistance cell line A2780-CR were separately seeded in 6-well cell culture plates and then exposed to multiple concentrations of cisplatin plus paclitaxel or topotecan for 7 days. Surviving cells were recovered and cultured in drug-free media for 3 weeks and then replated in a 96-well microtiter plate. The LD(50) for these cells was determined by a cytotoxic MTT assay after exposure to multiple clinically relevant concentrations of cisplatin or topotecan. Surviving cells were cultured in drug-free media for an additional 4 weeks at which time the LD(50) was reassessed for each cell population by a second MTT assay. Using RT-PCR and Northern blot hybridization to measure mRNA expression, the molecular profile of these cells in terms of resistance was evaluated for the multidrug-resistant gene (MDR-1), multidrug-resistant protein (MRP), Topoisomerase-I, and beta-Actin. RESULTS: The LD(50) to cisplatin was unchanged in A2780-CR cells treated by topotecan. Those A2780-CR cells originally exposed to higher concentrations of cisplatin became more resistant to cisplatin in the MTT assays, while those A2780-CR cell lines treated with a combination of lower cisplatin concentrations and paclitaxel became more sensitive to cisplatin in the MTT assay (P < 0.01). The second MTT assay demonstrated that the LD(50) for cisplatin in every cell line decreased significantly after a 4-week drug-free interval (P < 0.01). There was no difference in the mRNA expression for MRP or topoisomerase-I regardless of cell line, or type or concentration of chemotherapeutic exposure. The mRNA for MDR-1 was uniquely overexpressed in the cisplatin-resistant cell line A2780-CR9 initially treated with low doses of cisplatin and paclitaxel, but was not amplified in A2780 (P < 0.01). CONCLUSIONS: The acquired resistance to cisplatin in A2780 is potentially due to P-glycoprotein-mediated multidrug resistance. This acquired resistance to cisplatin is an unstable phenotype in that some cell populations become sensitive after a drug-free interval and topotecan treatment. This reversal of resistance, however, does not appear to be simply due to loss of MDR-1 expression. While in vivo confirmation is required, agents with novel mechanisms of action offer a strategy to extend the platinum-free interval and thereby improve survival in patients with recurrent ovarian cancer. SN - 0090-8258 UR - https://www.unboundmedicine.com/medline/citation/15262121/The_role_of_topotecan_for_extending_the_platinum_free_interval_in_recurrent_ovarian_cancer:_an_in_vitro_model_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0090825804002252 DB - PRIME DP - Unbound Medicine ER -