Lethal and sublethal effects of the combination of doxorubicin and the bisdioxopiperazine, (+)-1,2,-bis (3-5-dioxopiperazinyl-1-yl) propane (ICRF 187), on murine sarcoma S180 in vitro

Doxorubicin and the bisdioxopiperazine, ICRF 187, synergistically inhibit proliferation of murine sarcoma S180 cells in vitro. Cell cycle analysis was employed to help discriminate cytokinetic from lethal effects of the drug combination. Twenty-four-hour incubation with either agent produced dose-dependent partial G2M arrest. At high doses, ICRF 187 produced partial G2M arrest, inhibition of cell division, and continued DNA synthesis at a higher ploidy, resulting in a second G2M arrest of an 8n population. The addition of ICRF 187 to doxorubicin resulted in enhancement of cell cycle blockade at G2M. The combination also produced enhanced lethality as measured by reduced colony-forming efficiency of drug-treated S180 cells. Measurement of [14C]doxorubicin accumulation in, and effux from, ICRF 187 pretreated cells failed to reveal an effect of pretreatment with the bisdioxopiperazine on anthracycline disposition by S180 cells, suggesting that the enhanced cytotoxic and cytostatic effects do not result from increased intracellular concentrations of doxorubicin. The positive interaction between the two drugs may represent site-specific enhancement of the anthracycline effect by ICRF 187 at an intracellular target site.     

Phase II trial of ICRF-187 in children with solid tumors and acute leukemia

Summary ICRF-187 is the (+) enantiomer of the racemic mixture razoxane (ICRF-159). This compound is much more water soluble and thus could be formulated for parental use. The maximum tolerated dose in children after phase I trials was determined to be 3500 mg/M²/day × 3 days. A phase II trial of ICRF-187 was done in 21 children with solid tumors and 35 children with acute leukemia. All these patients were < 21 years of age, had recovered from previous chemotherapy, had normal liver and kidney functions, and had a life expectancy of greater than 4 weeks. ICRF-187 was administered at a dose of 3 g/M²/day for 3 days as a 4 hour infusion each day. In patients with leukemia, no objective response was seen in the bone marrow although a few patients had a decrease in peripheral blast count. There were no measurable responses seen in patients with a solid tumor. ICRF-187 was well tolerated. The major toxicity was hematopoietic depression. Significant but rare toxicities included moderate to severe nausea and vomiting, and elevation of bilirubin and transaminases. Although inactive in the current study, ICRF-187 might be more active in another schedule. Address for offprints: T. Vats (POG #8462), POG Operations Office, 4949 West Pine Boulevard, Suite 2A, St. Louis, MO 63108, USA     

Effect of ICRF-187 on the pulmonary damage induced by hyperoxia in the rat.

Histological and ultrastructural studies were made of the lungs of rats that were exposed to 100% oxygen for 60 h and were treated with either normal saline or with ICRF-187, a bis-diketopiperazine derivative of EDTA that has the capacity to chelate iron. This metal is thought to be needed to catalyze the formation of toxic oxygen free radicals. ICRF-187 (20 mg/kg) was given intraperitoneally at approximately 12 h intervals (5 doses) during the 60 h exposure. Seven of the ten saline-treated rats exposed to oxygen died prior to the end of the study whereas only one of the 10 rats in the ICRF-187-treated group died. This difference in mortality is found to be statistically significant (P less than 0.05). All saline-treated rats showed light and electron microscopic evidence of pulmonary damage. ICRF-187 attenuated the morphologic alterations observed by light microscopy (intra-alveolar edema, inflammatory exudates and bronchiolar epithelial cell swelling and hyperplasia; P less than 0.05). In addition, electron microscopic evaluation revealed that capillary thrombi, endothelial cell alterations and alveolar epithelial cell damage also were less severe in ICRF-187-treated rats. It is concluded that ICRF-187 may provide a new and useful approach for the prevention of hyperoxia-induced pulmonary damage.     

Characterisation of cytotoxicity and DNA damage induced by the topoisomerase II-directed bisdioxopiperazine anti-cancer agent ICRF-187 (dexrazoxane) in yeast and mammalian cells

Background

Bisdioxopiperazine anti-cancer agents are inhibitors of eukaryotic DNA topoisomerase II, sequestering this protein as a non-covalent protein clamp on DNA. It has been suggested that such complexes on DNA represents a novel form of DNA damage to cells. In this report, we characterise the cytotoxicity and DNA damage induced by the bisdioxopiperazine ICRF-187 by a combination of genetic and molecular approaches. In addition, the well-established topoisomerase II poison m-AMSA is used for comparison.

Results

By utilizing a panel of Saccharomyces cerevisiae single-gene deletion strains, homologous recombination was identified as the most important DNA repair pathway determining the sensitivity towards ICRF-187. However, sensitivity towards m-AMSA depended much more on this pathway. In contrast, disrupting the post replication repair pathway only affected sensitivity towards m-AMSA. Homologous recombination (HR) defective irs1SF chinese hamster ovary (CHO) cells showed increased sensitivity towards ICRF-187, while their sensitivity towards m-AMSA was increased even more. Furthermore, complementation of the XRCC3 deficiency in irs1SF cells fully abrogated hypersensitivity towards both drugs. DNA-PK_cs deficient V3-3 CHO cells having reduced levels of non-homologous end joining (NHEJ) showed slightly increased sensitivity to both drugs. While exposure of human small cell lung cancer (SCLC) OC-NYH cells to m-AMSA strongly induced γH2AX, exposure to ICRF-187 resulted in much less induction, showing that ICRF-187 generates fewer DNA double strand breaks than m-AMSA. Accordingly, when yeast cells were exposed to equitoxic concentrations of ICRF-187 and m-AMSA, the expression of DNA damage-inducible genes showed higher levels of induction after exposure to m-AMSA as compared to ICRF-187. Most importantly, ICRF-187 stimulated homologous recombination in SPD8 hamster lung fibroblast cells to lower levels than m-AMSA at all cytotoxicity levels tested, showing that the mechanism of action of bisdioxopiperazines differs from that of classical topoisomerase II poisons in mammalian cells.

Conclusion

Our results point to important differences in the mechanism of cytotoxicity induced by bisdioxopiperazines and topoisomerase II poisons, and suggest that bisdioxopiperazines kill cells by a combination of DNA break-related and DNA break-unrelated mechanisms.     

乙双吗啉(AT-1727)对L_(1210)细胞动力学的影响

以显微分光光度法结合放射自显影两种方法,研究了乙双吗啉对L_(1210)细胞动力学的影响。两种方法获得基本相似的结果。ip乙双吗啉50 mg/kg后,4 N细胞由未给药时的6.6%增加到23%,分裂细胞则明显减少,提示乙双吗啉可诱导G_2期细胞堆积。显微镜观察可见,堆积的G_2期细胞出现核肿胀,大量空泡,核破裂等现象,提示G_2期的阻断可能和G_2期细胞损伤有关。     

Dexrazoxane (ICRF-187)

• 1.Dexrazoxane (ICRF-187) is the only clinically approved drug for use in cancer patients to prevent anthracycline mediated cardiotoxicity.
• 2.The mode of action appears to be mainly due to the potential of the drug to remove iron from iron/anthracycline complexes and thus reduce free radical formation by these complexes.
• 3.Dexrazoxane also influences cell biology by its ability to inhibit topoisomerase II and its effects on the regulation of cellular iron homeostasis.
• 4.Although the cardioprotective effect of dexrazoxane in cancer patients undergoing chemotherapy with anthracyclines is well documented, the potential of this drug to modulate topoisomerase II activity and cellular iron metabolism may hold the key for future applications of dexrazoxane in cancer therapy, immunology, or infectious diseases.

     

Characterization of the biological and biochemical activities of F 11782 and the bisdioxopiperazines, ICRF-187 and ICRF-193, two types of topoisomerase II catalytic inhibitors with distinctive mechanisms of action

F 11782 is a newly identified catalytic inhibitor of topoisomerases I and II, without any detectable interaction with DNA. This study aimed to establish whether its catalytic inhibition of topoisomerase II was mediated by mechanisms similar to those identified for the bisdioxopiperazines. In vitro combinations of F 11782 with etoposide resulted in greater than additive cytotoxicity in L1210 cells, contrasting with marked antagonism for combinations of etoposide with either ICRF-187 or ICRF-193. All three compounds caused a G2/M blockade of P388 cells after an 18-h incubation, but by 40 h polyploidization was evident only with the bisdioxopiperazines. Gel retardation data revealed that only F 11782, and not the bisdioxopiperazines, was capable of completely inhibiting the DNA-binding activity of topoisomerase II, confirming its novel mechanism of action. Furthermore, unlike ICRF-187 and ICRF-193, the cytotoxicity of F 11782 appeared mediated, at least partially, by DNA damage induction in cultured GCT27 human teratoma cells, as judged by a fluorescence-enhancement assay and monitoring p53 activation. Finally, the major in vivo antitumor activity of F 11782 against the murine P388 leukemia (i.v. implanted) and the B16 melanoma (s.c. grafted) contrasted with the bisdioxopiperazines' general lack of activity. Overall, F 11782 and the bisdioxopiperazines appear to function as quite distinctive catalytic topoisomerase II inhibitors.     

乙双吗啉(AT-1727)对L1210细胞动力学的影响

以显微分光光度法结合放射自显影两种方法,研究了乙双吗啉对L₁₂₁₀细胞动力学的影响。两种方法获得基本相似的结果。ip乙双吗啉50 mg/kg后,4 N细胞由未给药时的6.6%增加到23%,分裂细胞则明显减少,提示乙双吗啉可诱导G₂期细胞堆积。显微镜观察可见,堆积的G₂期细胞出现核肿胀,大量空泡,核破裂等现象,提示G₂期的阻断可能和G₂期细胞损伤有关。     

Effect of ICRF-187 pretreatment against doxorubicin-induced delayed cardiotoxicity in the rat

Doxorubicin (DXR), administered iv in rats at the weekly dose of 3 mg/kg for 5 weeks, significantly impaired body weight gain and induced irreversible ECG alterations, mainly consisting of a progressive prolongation of ST and QT intervals. Five weeks after the last DXR administration, the contractile performance of atria isolated from treated animals was significantly reduced. At the same time, relevant morphologic lesions, consisting of myocyte vacuolization and myofibrillar loss, were also present in the myocardium of the same rats. The study showed that ICRF-187, administered ip at a dose of 125 mg/kg, significantly prevented body weight loss. QT and ST prolongation, and the decreased contractile force induced by DXR. In addition, ICRF-187 caused a significant reduction in incidence and severity of myocardial lesions. The cardioprotective effect of ICRF-187 is not mediated by a modification in DXR pharmacokinetics in heart, since the drug was actually found to increase DXR uptake in myocardial cells.     

Induction of apoptosis by dexrazoxane (ICRF-187) through caspases in the absence of c-jun expression and c-Jun NH2-terminal kinase 1 (JNK1) activation in VM-26-resistant CEM cells.

Dexrazoxane (ICRF-187) is an inhibitor of the catalytic activity of DNA topoisomerase II (topo II) that does not stabilize DNA-topo II covalent complexes. Here, we examined cytotoxic signaling by ICRF-187 in human leukemic CEM cells and a teniposide (VM-26)-resistant subline, CEM/VM-1. Treatment of CEM and CEM/VM-1 cells with ICRF-187 induced apoptotic cell death characterized by internucleosomal DNA fragmentation, nuclear condensation, and induction of at least caspase-3- and -7-like protease activities (but not caspase 1). Treatment of these cells with Z-Asp-2,6-dichlorobenzoyloxymethyl-ketone, a potent inhibitor of apoptosis, inhibited ICRF-187-induced DEVD-specific caspase activity and apoptosis in a concentration-dependent manner. ICRF-187-induced apoptosis in CEM cells was associated with transient induction of c-jun and activation of c-Jun NH2-terminal kinase 1 (JNK1). However, CEM/VM-1 cells, which were 3-fold more sensitive than CEM cells to ICRF-187 due to a decrease in topo II activity, exhibited ICRF-187-induced apoptosis in the absence of c-jun induction and JNK1 activation. These results indicate that catalytic inhibition of topo II by ICRF-187 leads to apoptosis through at least a caspase-3- and -7-like protease-dependent mechanism and suggest that c-jun and JNK1 are not required in ICRF-187-induced apoptosis in CEM cells.     

The catalytic DNA topoisomerase II inhibitor dexrazoxane (ICRF-187) induces differentiation and apoptosis in human leukemia K562 cells

The bisdioxopiperazines ICRF-187 (dexrazoxane), ICRF-193, and ICRF-154 are catalytic noncleavable complex-forming inhibitors of DNA topoisomerase II that do not produce protein-linked DNA strand breaks. In this study, we showed that bisdioxopiperazines induced erythroid differentiation, inhibited human leukemia K562 cell growth, and caused a slow induction of apoptosis. Dexrazoxane treatment caused DNA endoreduplication resulting in large highly polyploid cells. This result suggested the lack of a DNA topoisomerase II activity-based cell cycle checkpoint. The percentage of K562 cells that became apoptotic was much larger than the percentage of cells that stained for hemoglobin, suggesting that prior differentiation was not required for induction of apoptosis. Use of the Bcr-Abl tyrosine kinase inhibitor STI-571 resulted in a reduction in Bcl-xL levels and potentiation of dexrazoxane-induced apoptosis related to an earlier onset and more extensive cleavage of caspase-3. These results indicated that dexrazoxane-induced apoptosis is associated with a caspase-3 activation/cleavage pathway. In addition, these results were consistent with the antiapoptotic signaling function of Bcr-Abl to regulate expression of Bcl-xL. The ability of dexrazoxane to induce differentiation and apoptosis suggests that bisdioxopiperazines may be useful in treating some types of leukemia.     

Pretreatment with ICRF-187 allows a marked increase in the total cumulative dose of doxorubicin tolerated by beagle dogs

To study the influence of ICRF-187 on the functional and morphological effects of very large cumulative doses of doxorubicin, adult beagle dogs were given doxorubicin (1.75 mg/kg i.v.) either alone or 15 min after ICRF-187 (25 mg/kg, i.v.) at 3-week intervals. Control dogs received ICRF-187 (25 mg/kg, i.v.) or 0.9% saline without doxorubicin. Of eight animals receiving doxorubicin alone, two died after a total dose of 12.25 mg/kg and three died after 14 mg/kg; three others were in poor condition at the time of euthanasia after 14 mg/kg. Of eight animals receiving both ICRF-187 and doxorubicin, one died after 35 mg/kg, two died after 43.75 mg/kg and one died after 52.5 mg/kg; two dogs were euthanatized after 43.75 mg/kg because of difficulties encountered in giving i.v. injections, and two dogs survived a total dose of 52.5 mg/kg. All control dogs survived. None of the treatment or control groups developed consistent echocardiographic changes or alterations in mean arterial pressure. Dogs given ICRF-187 and doxorubicin developed PQ interval prolongation after 300 days and ventricular premature beats after 500 days. Each animal receiving doxorubicin alone had severe myocardial lesions (lesion score 3+). Of the animals given ICRF-187 and doxorubicin, one that received 35 mg/kg doxorubicin had no lesions; of four given 43.75 mg/kg, three had no lesions and one had minimal lesions (lesion score 1+); of three given 52.5 mg/kg, one had minimal (lesion score 1+) and two had moderate (lesion score 2+) lesions. Control animals had no myocardial lesions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Uranium induces genomic instability and slows cell cycle progression in human lymphocytes in acute toxicity study

In the situation of radiation triage, accidental exposure to uranium, or uranium contamination in food or water; haematopoietic decline or bone marrow sickness is observed in the aftermath followed by other systemic effects. Most studies done previously have been on cytogenetic analysis in blood lymphocytes of uranium miners wherein causal relationship was difficult to be established. This study provides new insights into the minimum risk level of uranium to human lymphocytes, DNA damage induced and alterations in the cell cycle progression through 96-h acute toxicity study. Cytotoxicity studies by MTT assay and flow cytometry showed that uranyl nitrate concentration of 1280 μM lead to 50% cell death, 640 μM caused 25% death, 250 μM caused 10% cell death and 5 μM was the NOAEL. Uranium caused DNA damages in a dose dependent manner as evident from comet and CBMN assays. A marked increase in G2/M phase cells was observed in the test culture groups. Halting of cell cycle at G2/M checkpoint also signified the extent of double strand breaks and genetic instability with increasing uranium dose in this study. Better cell cycle responses and lower genetic damage index observed in lower dosage of exposure, suggests adaptability and repair responses in human lymphocytes. Together these results advance our understanding of uranium effects on mammalian cells.     

Examination of the protective effect of ICRF-187 and dimethyl sulfoxide against acetaminophen-induced hepatotoxicity in Syrian golden hamsters

The protective activity of 1,2-bis(3,5-dioxopiperazin-l-yl)propane (ICRF-187) and dimethyl sulfoxide (DMSO) was tested against acetaminophen-induced hepatotoxicity. Male Syrian golden hamsters injected intraperitoneally between 18:00 h and 20:00 h for 2 consecutive days with acetaminophen (N-acetyl-p-aminophenol) (300 mg/kg) displayed signs of hepatotoxicity as evidenced by increases in enzyme activity and cellular damage. Forty-eight hours after the second acetaminophen dose, the activities of serum glutamic-pyruvic transaminase and alkaline phosphatase were increased compared with levels found in hamsters given only saline. In addition, hepatocellular necrosis was evident in acetaminophen-treated animals. ICRF-187 (300 mg/kg) given 1 h before acetaminophen attenuated the increases in enzyme activities, and both DMSO (7.3 g/kg) and ICRF-187 reduced the incidence and severity of acetaminophen-induced hepatocellular injury. Both ICRF-187 and DMSO are capable of altering free radical-mediated toxicity in other experimental systems. Whether these compounds reduce acetaminophen-induced liver toxicity by a similar mechanism remains to be determined.     

Characterization of a Chinese hamster ovary cell line with acquired resistance to the bisdioxopiperazine dexrazoxane (ICRF-187) catalytic inhibitor of topoisomerase II

A Chinese hamster ovary (CHO) cell line highly resistant to the non-cleavable complex-forming topoisomerase II inhibitor dexrazoxane (ICRF-187, Zinecard^®) was selected. The resistant cell line (DZR) was 1500-fold resistant (IC₅₀ = 2800 vs 1.8 μM) to continuous dexrazoxane exposure. DZR cells were also cross-resistant (8- to 500-fold) to other bisdioxopiperazines (ICRF-193, ICRF-154, and ICRF-186), and somewhat cross-resistant (4- to 14-fold) to anthracyclines (daunorubicin, doxorubicin, epirubicin, and idarubicin) and etoposide (8.5-fold), but not to the other non-cleavable complex-forming topoisomerase II inhibitors suramin and merbarone. The cytotoxicity of dexrazoxane to both cell lines was unchanged in the presence of the membrane-active agent verapamil. DZR cells were 9-fold resistant to dexrazoxane-mediated inhibition of topoisomerase II DNA decatenation activity compared with CHO cells (IC₅₀ = 400 vs 45 μM), but were only 1.4-fold (IC₅₀ = 110 vs 83 μM) resistant to etoposide. DZR cells contained one-half the level of topoisomerase II protein compared with parental CHO cells. However, the specific activity for decatenation using nuclear extract topoisomerase II was unchanged. Etoposide (100 μM)-induced topoisomerase II-DNA complexes in DZR cells and isolated nuclei were similarly one-half the level found in CHO cells and in isolated nuclei. However, the ability of 500 μM dexrazoxane to inhibit etoposide (100 μM)-induced topoisomerase II-DNA covalent complexes was reduced 4- to 6-fold in both DZR cells and nuclei compared with CHO cells and nuclei. In contrast, there was no differential ability of aclarubicin or merbarone to inhibit etoposide-induced topoisomerase II-DNA complexes in CHO compared with DZR cells and isolated nuclei. It was concluded that the DZR cell line acquired its resistance to dexrazoxane mainly through an alteration in the topoisomerase II target.     

半边旗抗肿瘤有效成分对HL—60细胞DNA拓扑异构酶活性及其细胞 …

目的；研究半边旗有效成分５Ｆ，６Ｆ，Ａ对ＨＬ－６０细胞ＤＮＡ拓扑异构酶活性和细胞周期的影响。方法：应用ｐＢＲ３２２质粒ＤＮＡ作为底物测定酶的活性；细胞周期用流式细胞仪测定；应用噻唑蓝法测定药物对细胞生长的抑制率。结果：５Ｆ，６Ｆ，Ａ均能够抑制ＤＮＡ拓扑异构酶Ⅰ，Ⅱ的活性。     

Bis(2-chloroethyl)sulfide (BCES) disturbs the progression of rat keratinocytes through the cell cycle

Epidermal basal keratinocytes are the primary target in BCES-induced cutaneous injury. DNA synthesis is inhibited by exposure to BCES which could relate to the mustard's cytotoxic effect. The effects of BCES on the cell cycle in keratinocytes synchronized by aphidicolin were investigated. Primary keratinocytes synchronized at the Gl/S boundary entered the S, G2, M, and G1 phases at successive times after release from the block. When cells were exposed to 1, 10, or 50 μM BCES in different phases of the cell cycle, cells in the S phase were more sensitive to BCES than cells in the other phases. Keratinocytes exposed to 1 μM BCES at the Gl/S boundary exhibited a prolongation of the S phase and a block in the G2 phase. When these cells were exposed to 10 or 50 μM BCES, they did not enter the S phase for up to 12 h and the incorporation of thymidine into DNA was inhibited. These results suggest that the blocks in the G2 and G1 phases relate to the cytotoxic effect of BCES on the germinative population of epidermal keratinocytes.     

Cross-talk between phosphatidic acid and ceramide during ethanol-induced apoptosis in astrocytes

Background

Anticancer bisdioxopiperazines, including ICRF-154, razoxane (Raz, ICRF-159) and ICRF-193, are a family of anticancer agents developed in the UK, especially targeting metastases of neoplasms. Two other bisdioxopiperazine derivatives, probimane (Pro) and MST-16, were synthesized at the Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. Cytotoxic activities and mechanisms of Raz (+)-steroisomer (ICRF-187, dexrazoxane), Pro and MST-16 against tumor cells were evaluated by MTT colorimetry, flow cytometry and karyotyping.

Results

Pro was cytotoxic to human tumor cell lines in vitro (IC₅₀<50 μM for 48 h). Four human tumor cell lines (SCG-7901, K562, A549 and HL60) were susceptible to Pro at low inhibitory concentrations (IC₅₀ values < 10 μM for 48 h). Although the IC₅₀ against HeLa cell line of vincristine (VCR, 4.56 μM), doxorubicin (Dox, 1.12 μM) and 5-fluoruouracil (5-Fu, 0.232 μM) are lower than Pro (5.12 μM), ICRF-187 (129 μM) and MST-16 (26.4 μM), VCR, Dox and 5-Fu shows a low dose-related – high cytotoxic activity. Time-response studies showed that the cytotoxic effects of Pro are increased for 3 days in human tumor cells, whereas VCR, Dox and 5-Fu showed decreased cytotoxic action after 24 h. Cell cycle G₂/M phase arrest and chromosome segregation blocking by Pro and MST-16 were noted. Although there was similar effects of Pro and MST-16 on chromosome segregation blocking action and cell cycle G₂/M phase arrest at 1- 4 μM, cytotoxicity of Pro against tumor cells was higher than that of MST-16 in vitro by a factor of 3- 10 folds. Our data show that Pro may be more effective against lung cancer and leukemia while ICRF-187 and MST-16 shows similar IC₅₀ values only against leukemia.

Conclusion

It suggests that Pro has a wider spectrum of cytotoxic effects against human tumor cells than other bisdioxopiperazines, especially against solid tumors, and with a single cytotoxic pathway of Pro and MST-16 affecting chromosome segregation and leading also to cell G₂/ M phase arrests, which finally reduces cell division rates. Pro may be more potent than MST-16 in cytotoxicity. High dose- and time- responses of Pro, when compared with VCR, 5-Fu and Dox, were seen that suggest a selectivity of Pro against tumor growth. Compounds of bisdioxopiperazines family may keep up their cytotoxic effects longer than many other anticancer drugs.