Reversal of Cisplatin and Multidrug Resistance by Ribozyme-Mediated Glutathione Suppression

Nagata, Junko; Kijima, Hiroshi; Hatanaka, Hiroyuki; Asai, Satoshi; Miyachi, Hayato; Takagi, Atsushi; Miwa, Takeshi; Mine, Tetsuya; Yamazaki, Hitoshi; Nakamura, Masato; Kondo, Takahito; Scanlon, Kevin J.; Ueyama, Yoshito

doi:10.1006/bbrc.2001.5399

Cited by 37 publications

(17 citation statements)

References 51 publications

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“…Formation of mitochondrial ROS appears to be increased by reversible glutathionylation of complex I as well (43). GSH depletion sensitizes cisplatin-resistant cancer cells (19,20). Conversely, treatments with N-acetyl-L-cysteine, a glutathione ester, or GSH are protective against cisplatininduced toxicity (44, 45).…”

Section: Discussionmentioning

confidence: 99%

“…Glutathione (GSH) depletion as a potential strategy to sensitize cancer cells has been under investigation for over two decades (14)(15)(16)(17)(18)(19)(20)(21)(22). Indeed, GSH and glutathione peroxidase (GPx) play central roles in cellular homeostasis by controlling the levels of ROS, and cancer cells tend to exhibit higher levels of ROS (22,23).…”

Section: Introductionmentioning

confidence: 99%

“…Several studies have associated GSH depletion with mitochondrial dysfunction, but the precise mechanism remains unclear (24). GSH depletion is commonly achieved using the inhibitor of GSH synthesis, L-buthionine sulfoximine (BSO), which has been shown to sensitize cancer cells to cisplatin treatment (19,20). However, limitations of this strategy include an inherent lack of specificity towards cancer cells and subsequent side effects (21).…”

Section: Introductionmentioning

confidence: 99%

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Selected flavonoids potentiate the toxicity of cisplatin in human lung adenocarcinoma cells: A role for glutathione depletion

Kachadourian

Leitner²,

Day³

2007

Int J Oncol

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Abstract. Adjuvant therapies that enhance the anti-tumor effects of cis-diammineplatinum(II) dichloride (cisplatin, CDDP) are actively being pursued. Growing evidence supports the involvement of mitochondrial dysfunction in the anti-cancer effect of cisplatin. We examined the potential of using selective flavonoids that are effective in depleting tumor cells of glutathione (GSH) to potentiate cisplatin-mediated cytotoxicity in human lung adenocarcinoma (A549) cells. We found that cisplatin (40 μM, 48-h treatment) disrupts the steady-state levels of mitochondrial respiratory complex I, which correlates with elevated mitochondrial reactive oxygen species (ROS) production and cytochrome c release. The flavonoids, 2',5'-dihydroxychalcone (2',5'-DHC, 20 μM) and chrysin (20 μM) potentiated the cytotoxicity of cisplatin (20 μM), which could be blocked by supplementation of the media with exogenous GSH (500 μM). Both 2',5'-DHC and chrysin were more effective than the specific inhibitor of GSH synthesis, L-buthionine sulfoximine (BSO, 20 μM), in inducing GSH depletion and potentiating the cytotoxic effect of cisplatin. These data suggest that the flavonoid-induced potentiation of cisplatin's toxicity is due, in part, to synergetic pro-oxidant effects of cisplatin by inducing mitochondrial dysfunction, and the flavonoids by depleting cellular GSH, an important antioxidant defense.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Selected flavonoids potentiate the toxicity of cisplatin in human lung adenocarcinoma cells: A role for glutathione depletion

Kachadourian

Leitner²,

Day³

2007

Int J Oncol

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“…A second strategy that has not been tested clinically involves the use of a hammerhead ribozyme against g-GCS mRNA to downregulate its levels specifically (Nagata et al, 2001). In vitro this strategy has been shown to enhance sensitivity to a variety of chemotherapeutic agents, most probably by affecting target repair as well as modulating MRP-mediated drug efflux.…”

Section: Depletion Of Glutathione To Modulate Drug Resistancementioning

confidence: 99%

Strategies for reversing drug resistance

2003

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“…22) Briefly, the specific PCR products were size-fractionated by horizontal agarose gel electrophoresis, and stained with ethidium bromide. The authentic sense primer for γ-GCSh was 5′-CCAGTTCCTGCACATCTACCACG-3′, and the antisense primer was 5′-GTCGCTGGG-GAGTGATTTCTGC-3′.…”

Section: )mentioning

confidence: 99%

Hammerhead Ribozyme against γ‐Glutamylcysteine Synthetase Attenuates Resistance to Ionizing Radiation and Cisplatin in Human T98G Glioblastoma Cells

Tani

Goto

Kamada

et al. 2002

Japanese Journal of Cancer Research

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Glioblastoma cells are highly malignant and show resistance to ionizing radiation, as well as anticancer drugs. This resistance to cancer therapy is often associated with a high concentration of glutathione (GSH). In this study, the effect of continuous down-regulation of γ γ γ γ-glutamylcysteine synthetase (γ γ γ γ-GCS) expression, a rate-limiting enzyme for GSH synthesis, on resistance to ionizing radiation and cisplatin (CDDP) was studied in T98G human glioblastoma cells. We constructed a hammerhead ribozyme against a γ γ γ γ-GCS heavy subunit (γ γ γ γ-GCSh) mRNA and transfected it into Key words: γ-Glutamylcysteine synthetase -Hammerhead ribozyme -Glutathione -CisplatinIonizing radiationResistance of malignant cells to radiotherapy and chemotherapy is a major problem in the treatment of cancers. Glioblastoma is one of the most malignant forms of neoplasm, and often shows resistance to radio-and chemotherapy.1) This resistance is due to direct factors, such as a low intrinsic radiation sensitivity, a high recovery capacity, an increased number of clonogens, and a high hypoxic fraction.2) Glutathione (γ-glutamylcysteinylglycine, GSH), participates in many biological processes, especially cellular defense against oxidative stress induced by reactive oxygen species (ROS) and anti-cancer drugs.3-5) GSH is synthesized via two ATP-requiring steps that are catalyzed by γ-glutamylcysteine synthetase (γ-GCS), a rate-limiting enzyme for the synthesis of GSH, and GSH synthetase. γ-GCS is composed of a heavy subunit (γ-GCSh) that is catalytic, and a light subunit (γ-GCSl) that is regulatory. 6, 7)We previously found that γ-GCS is over-expressed in T98G human glioblastoma cells concomitant with a high concentration of GSH. 8) Since ionizing radiation produces ROS inside the cells, over-expression of γ-GCS was thought to be an important factor in the acquisition of T98G glioblastoma cell resistance to ionizing radiation. The over-expression of γ-GCS has also been reported in many human malignant cells resistant to cisplatin [cisdiamminedichloroplatinum (II)] (CDDP) and doxorubicin.9-13) Recently, we reported that the two subunits of γ-GCS are concomitantly expressed in response to CDDP in human cancer cells. 9) We also reported that CDDP is transported in the form of a CDDP-GSH adduct 14) and that GSH S-transferase π (GSTπ) detoxifies CDDP by forming an adduct with GSH, and is thus important for the efflux of CDDP.15) These findings suggest that a high concentration of GSH is a factor in malignant cell acquisition of resistance to anti-cancer drugs as well as ionizing radiation.Concerning the expression of γ-GCS, Manna et al. reported that over-expression of γ-GCS heavy subunit suppresses tumor necrosis factor-induced apoptosis and the DNA-binding activity of nuclear factor-κB (NF-κB) and activator protein-1 (AP-1), 16) suggesting an important role for γ-GCS in regulating cell proliferation and death.In this study, we developed a hammerhead ribozyme against γ-GCSh to constitutively suppress the γ-GCSh gene expression in T9...

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Reversal of Cisplatin and Multidrug Resistance by Ribozyme-Mediated Glutathione Suppression

Cited by 37 publications

References 51 publications

Selected flavonoids potentiate the toxicity of cisplatin in human lung adenocarcinoma cells: A role for glutathione depletion

Selected flavonoids potentiate the toxicity of cisplatin in human lung adenocarcinoma cells: A role for glutathione depletion

Strategies for reversing drug resistance

Hammerhead Ribozyme against γ‐Glutamylcysteine Synthetase Attenuates Resistance to Ionizing Radiation and Cisplatin in Human T98G Glioblastoma Cells

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