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Generation and characterization of a low-degree drug-resistant human tumor cell line
Abstract:
A 2780 human ovarian cancer cells, obtained from an untreated patient, have been exposed to a relatively low, clinically maintainable dose (10 nmol/l) of the anthracycline doxorubicin (DX) to derive a low-degree (5-fold) drug-resistant subline (A2780-DX1). Compared to parental cells, these DX-resistant cells have increased size (+60% of cell volume) and contain a greater number of cytoplasmic vacuoles as determined by electron microscopy. When exposed to several other antiproliferative drugs, A2780-DX1 cells were highly cross-resistant (greater than 10-fold) to epirubicin, mafosfamide and cisplatin and slightly cross-resistant (2- to 3-fold) to navelbine and bleomycin, while they retained the original sensitivity to vinblastine, Ara-C and fluorouracil. Gel electrophoresis of cytoplasmic membrane proteins showed differences between the pattern of parental A2780 sensitive and A2780-DX1 cells as far as low-molecular-weight proteins (less than 45 kD) are concerned, while no clear overexpression of P-glycoprotein (P-170) could be detected. Membrane modifications yielding a decrease of both DX uptake and retention, increased content of intracellular glutathione (+32%) and reduced DNA double-strand breaks seem to be involved in the resulting multidrug-resistant phenotype of A2780-DX1 cells.
Insights
Low-dose doxorubicin (DX) exposure created drug-resistant ovarian cancer cells (A2780-DX1). These cells exhibit cross-resistance to multiple chemotherapy agents, suggesting altered cellular mechanisms contribute to multidrug resistance.
Area of Science:
- Oncology
- Cell Biology
- Pharmacology
Background:
- Doxorubicin (DX) is a key anthracycline chemotherapy agent.
- Acquired drug resistance limits the efficacy of cancer treatments.
- Understanding resistance mechanisms is crucial for developing effective therapies.
Purpose of the Study:
- To generate and characterize a doxorubicin (DX)-resistant human ovarian cancer cell line (A2780-DX1).
- To investigate the cross-resistance profile of the A2780-DX1 subline against other antiproliferative drugs.
- To explore potential cellular mechanisms underlying the observed multidrug resistance.
Main Methods:
- Exposure of A2780 human ovarian cancer cells to a low dose of doxorubicin (DX) to establish the A2780-DX1 subline.
- Comparative analysis of cell volume and cytoplasmic vacuolation using electron microscopy.
- Assessment of cross-resistance to various chemotherapy drugs.
- Analysis of cytoplasmic membrane proteins via gel electrophoresis.
- Measurement of doxorubicin uptake and retention, intracellular glutathione levels, and DNA double-strand breaks.
Main Results:
- The A2780-DX1 subline showed a 5-fold resistance to doxorubicin (DX) and significant cross-resistance (>10-fold) to epirubicin, mafosfamide, and cisplatin.
- A2780-DX1 cells exhibited increased cell volume (+60%) and more cytoplasmic vacuoles compared to parental cells.
- Reduced DX uptake and retention, increased intracellular glutathione (+32%), and fewer DNA double-strand breaks were observed in A2780-DX1 cells.
- No clear overexpression of P-glycoprotein (P-170) was detected, but differences in low-molecular-weight cytoplasmic membrane proteins were noted.
Conclusions:
- Low-dose doxorubicin (DX) can induce a multidrug-resistant phenotype in ovarian cancer cells.
- The resistance mechanism involves alterations in drug transport, increased glutathione levels, and reduced DNA damage, independent of P-glycoprotein (P-170) overexpression.
- These findings highlight the complexity of acquired chemoresistance and suggest potential targets for overcoming resistance in ovarian cancer.