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Serine protease inhibition and mitochondrial dysfunction associated with cisplatin resistance in human tumor cell
Y Dong1, S J Berners-Price, D R Thorburn
1Department of Obstetrics and Gynaecology, University of Queensland, Australia.
Abstract:
Indicators of mitochondrial function were studied in two different cell culture models of cis-diamminedichloroplatinum-II (CDDP) resistance: the intrinsically resistant human ovarian cancer cell line CI-80-13S, and resistant clones (HeLa-S1a and HeLa-S1b) generated by stable expression of the serine protease inhibitor-plasminogen activator inhibitor type-2 (PAI-2), in the human cervical cancer cell line HeLa. In both models, CDDP resistance was associated with sensitivity to killing by adriamycin, etoposide, auranofin, bis[1,2-bis(diphenylphosphino)ethane]gold(I) chloride ([Au(DPPE)2]Cl), CdCl2 and the mitochondrial inhibitors rhodamine-123 (Rh123), dequalinium chloride (DeCH), tetraphenylphosphonium (TPP), and ethidium bromide (EtBr) and with lower constitutive levels of ATP. Unlike the HeLa clones, CI-80-13S cells were additionally sensitive to chloramphenicol, 1-methyl-4-phenylpyridinium ion (MPP+), rotenone, thenoyltrifluoroacetone (TTFA), and antimycin A, and showed poor reduction of 1-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT), suggesting a deficiency in NADH dehydrogenase and/or succinate dehydrogenase activities. Total platinum uptake and DNA-bound platinum were slightly lower in CI-80-13S than in sensitive cells. The HeLa-S1a and HeLa-S1b clones, on the other hand, showed poor reduction of triphenyltetrazolium chloride (TTC), indicative of low cytochrome c oxidase activity. Total platinum uptake by HeLa-Sla was similar to HeLa, but DNA-bound platinum was much lower than for the parent cell line. The mitochondria of CI-80-13S and HeLa-S1a showed altered morphology and were fewer in number than those of JAM and HeLa. In both models, CDDP resistance was associated with less platinum accumulation and with mitochondrial and membrane defects, brought about one case with expression of a protease inhibitor which is implicated in tumor progression. Such markers may identify tumors suitable for treatment with gold phosphine complexes or other mitochondrial inhibitors.
Insights
cis-diamminedichloroplatinum-II (CDDP) resistance in cancer cells involves mitochondrial defects and altered platinum accumulation. These findings suggest potential therapeutic targets like gold phosphine complexes for specific tumors.
Area of Science:
- Biochemistry
- Cell Biology
- Oncology
Background:
- Cis-diamminedichloroplatinum-II (CDDP) is a widely used chemotherapy drug.
- Understanding mechanisms of CDDP resistance is crucial for improving cancer treatment outcomes.
- Mitochondrial dysfunction is increasingly recognized as a factor in cancer drug resistance.
Purpose of the Study:
- To investigate mitochondrial function in two distinct models of CDDP resistance.
- To identify potential biomarkers for predicting response to CDDP and other therapies.
- To explore the role of mitochondrial defects in acquired and intrinsic CDDP resistance.
Main Methods:
- Utilized intrinsically resistant ovarian cancer cells (CI-80-13S) and CDDP-resistant HeLa clones (HeLa-S1a, HeLa-S1b) expressing plasminogen activator inhibitor type-2 (PAI-2).
- Assessed sensitivity to various chemotherapeutic agents and mitochondrial inhibitors (e.g., rhodamine-123, dequalinium chloride).
- Measured cellular ATP levels, mitochondrial morphology, platinum uptake, and DNA-bound platinum.
Main Results:
- CDDP resistance correlated with sensitivity to adriamycin, etoposide, gold complexes, and mitochondrial inhibitors, alongside lower ATP levels.
- CI-80-13S cells exhibited deficiencies in NADH/succinate dehydrogenase and reduced MTT assay activity.
- HeLa clones showed reduced triphenyltetrazolium chloride reduction, indicating low cytochrome c oxidase activity, and decreased DNA-bound platinum.
Conclusions:
- CDDP resistance is linked to mitochondrial defects, altered platinum accumulation, and membrane abnormalities.
- Specific mitochondrial dysfunctions, like impaired dehydrogenase or cytochrome c oxidase activity, are associated with different resistance mechanisms.
- These mitochondrial and membrane alterations may serve as biomarkers for identifying tumors responsive to gold phosphine complexes or other mitochondrial inhibitors.