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At least 19 recordsLinked to original sources

Antitumor activity of a derivative of mitomycin, 7-N-[2-[[2-(gamma-L-glutamylamino)ethyl]dithio]ethyl]mitomycin C (KW-2149), against murine and human tumors and a mitomycin C-resistant tumor in vitro and in vivo.

The antitumor activity of a mitomycin derivative, 7-N-[2[[2-(gamma-glutamylamino)ethyl]dithio]ethyl]mitomycin C (KW-2149), was evaluated in murine and human tumor models, including a mitomycin C (MMC)-resistant tumor in vitro and in vivo. KW-2149 showed a profound effect against i.p. inoculated P388 leukemia on both a single and an intermittent administration schedule. Against s.c. implanted colon adenocarcinoma 38 (colon 38). KW-2149 was as effective as MMC in ILS% and in tumor growth inhibition on a single-administration schedule. Both compounds were similarly effective when an intermittent schedule was used. KW-2149 showed activity against human tumor xenografts and was effective in two of four non-small-cell lung carcinomas but was not effective against three gastric adenocarcinomas on the single-administration regimen. The activity of KW-2149 against gastric adenocarcinoma was inferior to that of MMC on a single-administration schedule. However, the antitumor activity of KW-2149 was higher on an intermittent schedule than on a single-administration regimen. The antitumor activity of KW-2149 against human tumor xenografts was similar to that of MMC on an intermittent schedule, and the former drug was effective against both gastric adenocarcinomas and both non-small-cell lung carcinomas. KW-2149 was more effective than MMC against a subline of P388 leukemia that is resistant to MMC in vitro as well as in vivo.

Adenocarcinoma↗

Nonenzymatic reductive activation of 7-N-((2-([2-(gamma-L-glutamylamino)ethyl]dithio)ethyl))mitomycin C by thiol molecules: a novel mitomycin C derivative effective on mitomycin C-resistant tumor cells.

7-N-((2-([2-(gamma-L-Glutamylamino)ethyl]dithio)ethyl))mitomycin C (KW-2149) is an analogue of mitomycin C (MMC) and has prominent activities against various tumors. We studied the antitumor effects of KW-2149 in MMC-resistant variants of human colon carcinoma HT-29 (HT-29/MMC) and mouse hepatoma Hepa-I (C4, B13NBii1) cells, which are deficient in DT-diaphorase and cytochrome P450 reductase, respectively. These enzymes mediate the reductive activation of MMC in the cells. Although HT-29/MMC and C4, B13NBii1 cells showed significant resistance to MMC, they showed sensitivity tl KW-2149 comparable to their parental tumors, indicating that DT-diaphorase and cytochrome P450 reductase could not be involved in the activation of KW-2149. In studying the activation mechanism of KW-2149, we found that glutathione (GSH) and cysteine significantly enhanced the cytotoxicity of KW-2149 in HT-29 cells. The DNA adduct of KW-2149 was increased when HT-29 cells or the isolated nuclei of the cells were incubated with KW-2149 in the presence of physiological concentrations of GSH and cysteine. KW-2149 alkylated calf thymus DNA in the presence of GSH and cysteine in vitro. These results indicate that activation of KW-2149 by thiol molecules, unlike MMC, could be an important activation mechanism of KW-2149 to form DNA adduct and to exert its cytotoxicity. This is the reason why KW-2149 is effective against MMC-resistant tumors with deficiencies in the MMC activation enzymes.

Buthionine Sulfoximine↗

Metabolism of mitomycin C by DT-diaphorase: role in mitomycin C-induced DNA damage and cytotoxicity in human colon carcinoma cells.

The role of DT-diaphorase in bioreductive activation of mitomycin C was examined using HT-29 and BE human carcinoma cells which have high and low levels of DT-diaphorase activity, respectively. HT-29 cells were more sensitive to mitomycin C-induced cytotoxicity than the DT-diaphorase-deficient BE cell line. Mitomycin C induced DNA interstrand cross-linking in HT-29 cells but not in BE cells. Both mitomycin C-induced cytotoxicity and induction of DNA interstrand cross-links could be inhibited by pretreatment of HT-29 cells with dicoumarol. Metabolism of mitomycin C by HT-29 cell cytosol was pH dependent and increased as the pH was lowered to 5.8, the lowest pH tested. Metabolism of mitomycin C by HT-29 cytosol was inhibited by prior boiling of cytosol or by the inclusion of dicoumarol. Little metabolism was detected in BE cytosols. When purified rat hepatic DT-diaphorase was used, metabolism of mitomycin C increased as the pH was decreased and could be detected at pH 5.8, 6.4, 7.0, 7.4, but not at 7.8. Metabolism of mitomycin C was NADH dependent and inhibited by dicoumarol or by prior boiling of enzyme. An approximate 1:1 stoichiometry between NADH and mitomycin C removal was demonstrated and no oxygen consumption could be detected. Metabolism of mitomycin C by purified HT-29 DT-diaphorase was also dicoumarol inhibitable and pH dependent. The major metabolite formed during metabolism of mitomycin C by HT-29 cytosol, purified HT-29, and rat hepatic DT-diaphorase was characterized as 2,7-diaminomitosene. These data suggest that two-electron reduction of mitomycin C by DT-diaphorase may be an important determinant of mitomycin C-induced genotoxicity and cytotoxicity.

Antineoplastic Agents↗

Inhibition of DNA cross-linking by mitomycin C by peroxidase-mediated oxidation of mitomycin C hydroquinone.

Mitomycin C requires reductive activation to cross-link DNA and express anticancer activity. Reduction of mitomycin C (40 microm) by sodium borohydride (200 microm) in 20 mm Tris-HCl, 1 mm EDTA at 37 degrees C, pH 7.4, gives a 50-60% yield of the reactive intermediate mitomycin C hydroquinone. The hydroquinone decays with first order kinetics or pseudo first order kinetics with a t(12) of approximately 15 s under these conditions. The cross-linking of T7 DNA in this system followed matching kinetics, with the conversion of mitomycin C hydroquinone to leuco-aziridinomitosene appearing to be the rate-determining step. Several peroxidases were found to oxidize mitomycin C hydroquinone to mitomycin C and to block DNA cross-linking to various degrees. Concentrations of the various peroxidases that largely blocked DNA cross-linking, regenerated 10-70% mitomycin C from the reduced material. Thus, significant quantities of products other than mitomycin C were produced by the peroxidase-mediated oxidation of mitomycin C hydroquinone or products derived therefrom. Variations in the sensitivity of cells to mitomycin C have been attributed to differing levels of activating enzymes, export pumps, and DNA repair. Mitomycin C hydroquinone-oxidizing enzymes give rise to a new mechanism by which oxic/hypoxic toxicity differentials and resistance can occur.

Borohydrides↗

Combination chemotherapy with doxorubicin and mitomycin C in non-small cell bronchogenic carcinoma. Severe pulmonary toxicity from q 3 weekly mitomycin C.

Forty-five patients with advanced, measurable, or evaluable non-small bronchogenic carcinoma (NSCBC) were treated with doxorubicin and mitomycin C combination chemotherapy. The first 27 patients received doxorubicin 50 mg/m2 I.V. every 3 weeks and mitomycin C 10 mg/m2 I.V. every 3 weeks. Because of severe cardiopulmonary toxicity in seven patients, with four otherwise unexplained deaths, the next 18 patients were treated with the mitomycin C dose reduced to 10 mg/m2 every 6 weeks. Overall, 11 patients (25%) responded, with one complete and 10 partial remissions. Eight responses (30%) were observed in the patients who received mitomycin C every 3 weeks and three responses (17%) were found in those given mitomycin C every 6 weeks (p less than 0.5), with no cardiopulmonary toxicity in the latter group. The median survival was 21 weeks for the entire group of patients, with the group receiving mitomycin C every 3 weeks living a median of 15.5 weeks and those given mitomycin C every 6 weeks surviving 35.5 weeks (p less than 0.025). We conclude that there is a higher tumor response rate but more cardiopulmonary toxicity and shorter survival among the group receiving mitomycin C every 3 weeks compared to those receiving mitomycin C every 6 weeks. Future studies should consider this toxicity of mitomycin C administered on an every-3-week schedule.

Adult↗

Reductive activation of mitomycin C and mitomycin C metabolites catalyzed by NADPH-cytochrome P-450 reductase and xanthine oxidase.

Under anaerobic conditions and with proper electron donors, NADPH-cytochrome P-450 reductase (EC 1.6.2.4) and xanthine oxidase (EC 1.2.3.2) similarly reductively metabolized mitomycin C. Reversed phase high performance liquid chromatography was used to separate, detect, and isolate several metabolites. Three metabolites were identified by mass spectrometry and thin layer chromatography as 1,2-cis- and trans-2,7-diamino-1-hydroxymitosene and 2,7-diaminomitosene. Three metabolites were phosphate-dependent, and two of them were identified to be 1,2-cis- and trans-2,7-diaminomitosene 1-phosphate. The amounts of the five identified metabolites generated during the reduction of mitomycin C varied with pH and nucleophile concentration. At pH 6.5, 2,7-diaminomitosene was essentially the only metabolite formed, whereas from pH 6.8 to 8.0, trans- and cis-2,7-diamino-1-hydroxymitosene increased in quantity as 2,7-diaminomitosene decreased. The disappearance of mitomycin C and the production of metabolites were enzyme and mitomycin C concentration-dependent. Substrate saturation was not reached for either enzyme up to 5 mM mitomycin C. Electron paramagnetic resonance studies demonstrated the formation of mitomycin C radical anion as an intermediate during enzymatic activation. Our results indicate that either enzyme catalyzed the initial activation of mitomycin C to a radical anion intermediate. Subsequent spontaneous reactions, including the elimination of methanol and the opening of the aziridine ring, generate one active center at C-1 which facilitates nucleophilic attack. Simultaneous generation of two reactive centers was not observed. All five primary metabolites were metabolized further by either flavoenzyme. The secondary metabolites exhibited similar changes in their absorbance spectra and were unlike the primary metabolites, suggesting that a second alkylating center other than C-1 was generated during secondary activation. We propose that secondary activation of monofunctionally bound mitomycin C is probably a main route for the bifunctional binding of mitomycin C to macromolecules and that the cytotoxic actions of mitomycin C result from multiple metabolic activations and reactions.

Animals↗

Sequence-specific DNA damage induced by reduced mitomycin C and 7-N-(p-hydroxyphenyl)mitomycin C.

Mitomycin C reduced with sodium borohydride induced the DNA damage at deoxyguanosines preferentially in dinucleotide sequence G-T. The DNA damage produced strand breaks when subsequently heated. The DNA damage scarcely occurred when the end-labeled DNA was preincubated with ethidium bromide or actinomycin D before the addition of mitomycin C and the reducing agent. Fully reduced mitomycin C did not induce the DNA damage. The mitomycin C-inducing DNA damage seems to require the intercalation of the partially reduced mitomycin C of short life time, probably semiquinone radical, between DNA base pairs. The inhibitory effects of sodium chloride and radical scavengers suggested that the requirement of the covalent bond formation of mitomycin C to DNA and the involvement of oxygen radicals in the DNA damage. 7-N-(p-hydroxyphenyl)mitomycin C, which is reported to show a higher antitumor activity and a lower toxicity than mitomycin C, was readily reduced with dithiothreitol and induced the sequence-specific DNA damage, whereas mitomycin C was not.

Bacteriophage phi X 174↗

Structure-activity relationships for mitomycin C and mitomycin A analogues.

A set of 30 mitomycin C and mitomycin A analogues, including five new compounds, was screened against three different solid human tumor cell lines using the MTT tetrazolium dye assay. A statistically significant correlation among antitumor activity, quinone reduction potential (E1/2), and the logarithm of the partition coefficient (log P) was obtained, with the most easily reduced and the most lipophilic compounds being the most potent. When these analogues were separated into mitomycin C and mitomycin A subsets, the former gave a correlation only with E1/2, whereas the latter (which differ little in their E1/2 values) gave a correlation only with log P. These correlations are in contrast to those made in the P388 leukemia assay in mice wherein the most active mitomycin C and mitomycin A analogues were the most hydrophilic ones. When the same compounds were tested against P388 leukemia cells in the MTT assay, the results were the same as those of the solid tumor assays. Thus, the substantial differences in relative potencies of mitomycins are related not to the kind of tumor cell, but to the type of assay performed, cell culture versus whole animal. No correlation was found between antitumor potency in the cell culture systems and calculated relative DNA binding strengths, probably because the limiting factors in antitumor potency of mitomycins appear to be tumor cell uptake (log P) and/or bioreductive activation (E1/2).

Animals↗

A phase III trial of mitomycin C alone versus mitomycin C, vinblastine, and cisplatin for metastatic squamous cell lung carcinoma.

BACKGROUND: In an effort to confirm the efficacy of mitomycin C against metastatic squamous cell lung carcinoma and to compare the efficacy of single-agent therapy with a combination containing cisplatin, the authors conducted a randomized Phase III trial of mitomycin C alone versus mitomycin C, vinblastine, and cisplatin (MVP). METHODS: All patients had advanced squamous cell lung carcinoma, and survival was the primary end point. There were 133 eligible patients who received either mitomycin C alone (n = 64) or MVP (n = 69). The two groups were similar with respect to performance score, disease status, age, sex, and stage. RESULTS: The major objective response rates were 30% (95% confidence interval [CI], 18-41%) and 43% (95% CI, 32-55%) for mitomycin C alone and MVP, respectively (P = 0.1). The median time to progression was 83 days for mitomycin C alone, compared with 119 days for MVP (P = 0.026). The median survival time was 114 days for mitomycin C and 163 days for MVP (P = 0.09). The 1-year survival rates were equivalent. Myelosuppression was the major toxicity, and there were significantly greater leukocyte nadirs with MVP therapy (P < 0.001). CONCLUSION: Mitomycin C has antitumor activity against squamous cell lung carcinoma when used alone or in combination with MVP. The regimen containing cisplatin had marginally increased activity that did not translate into a clinically significant survival advantage.

Adult↗

Results of a randomized phase III trial of sequential intravesical therapy with mitomycin C and bacillus Calmette-Guerin versus mitomycin C alone in patients with superficial bladder cancer.

PURPOSE: We study toxicity and efficacy of sequential intravesical therapy with mitomycin C and bacillus Calmette-Guerin (BCG) in patients with intermediate or high risk superficial bladder cancer compared to the use of intravesical mitomycin C alone. MATERIALS AND METHODS: Patients with intermediate and high risk papillary superficial bladder cancer and carcinoma in situ were randomized after transurethral resection between 4 weekly instillations with 40 mg. mitomycin C followed by 6 weekly instillations with BCG (group 1, 90 patients) or 10 weekly instillations with mitomycin C (group 2, 92 patients). RESULTS: The frequency of bacterial and chemical cystitis, and other local side effects was similar in both groups. Allergic reactions, including skin rash, were more frequent in the mitomycin C only group (12 of 92 patients versus 5 of 90, p = 0.08), and other systemic side effects were more frequent in the sequential group (16 of 90 versus 8 of 92, p = 0.07). After a median followup of 32 months the number of recurrences (sequential 35 of 90 patients versus mitomycin C only 42 of 92, p = 0.36) and progression (5 of 90 versus 4 of 92 respectively, p = 0.70) were similar in both groups. CONCLUSIONS: We did not find any major differences in toxicity or treatment efficacy with intravesical mitomycin C and the sequential use of BCG or mitomycin C for intermediate and high risk superficial papillary bladder cancer.

Adjuvants, Immunologic↗

Cardiotoxicity of mitomycin A, mitomycin C, and seven N7 analogs in vitro.

The alkylating antitumor agents mitomycin A (MMA), mitomycin C (MMC), and seven N7 analogs were compared in terms of their cardiotoxic and antitumor activity in vitro. Neonatal rat-heart myocytes were sensitive to five of the compounds studied, including MMA, 7-dimethylamidinomitosane (BMY-25282), 7-(N-methyl-piperazinyl)-mitosane (RR-194), N7-(4-iodophenyl)-MMC (RR-208), and N7-(4-hydroxyphenyl)-MMC (M-83) in order of descending molar potency. MMA and RR-208 possessed the greatest cytotoxic potency against 8226 human myeloma tumor cells in vitro. Two of the nine mitomycins studied, BMY-25282 and M-83, showed greater cytotoxic potency for heart cells. For these two agents, the ratio of the 50% inhibitory concentration in heart cells to that in 8226 myeloma cells was 50 and 32, respectively. For the other analogs, the tumor-cell cytotoxic potency was much higher (ranging from 200 to 7,000). For the nine mitomycin compounds, a correlation was found between heart-cell toxicity and low reduction potentials (E1/2 values) ranging from -0.16 to -0.37 V. Thus, as the reduction potential decreased (easier reducibility), the cardiotoxic potency in vitro increased (r = 0.81). In contrast, mitomycins with reduction potentials of higher than -0.37 V were much less potent cardiotoxins. Thus, mitomycin C (E1/2 = -0.45 V) was noncardiotoxic even when tested at concentrations 100-fold above those pharmacologically achievable in humans. Mitomycin C also failed to enhance doxorubicin (Adriamycin) cardiotoxicity in vitro. Importantly, no correlation was found between the reduction potential and the antitumor activity of the nine analogs (n = 0.51), in this small series.

Adenosine Triphosphate↗

Mitomycin resistance in mammalian cells expressing the bacterial mitomycin C resistance protein MCRA.

The mitomycin C-resistance gene, mcrA, of Streptomyces lavendulae produces MCRA, a protein that protects this microorganism from its own antibiotic, the antitumor drug mitomycin C. Expression of the bacterial mcrA gene in mammalian Chinese hamster ovary cells causes profound resistance to mitomycin C and to its structurally related analog porfiromycin under aerobic conditions but produces little change in drug sensitivity under hypoxia. The mitomycins are prodrugs that are enzymatically reduced and activated intracellularly, producing cytotoxic semiquinone anion radical and hydroquinone reduction intermediates. In vitro, MCRA protects DNA from cross-linking by the hydroquinone reduction intermediate of these mitomycins by oxidizing the hydroquinone back to the parent molecule; thus, MCRA acts as a hydroquinone oxidase. These findings suggest potential therapeutic applications for MCRA in the treatment of cancer with the mitomycins and imply that intrinsic or selected mitomycin C resistance in mammalian cells may not be due solely to decreased bioactivation, as has been hypothesized previously, but instead could involve an MCRA-like mechanism.

Aerobiosis↗

Effect of photodynamic therapy in combination with mitomycin C on a mitomycin-resistant bladder cancer cell line.

Photodynamic therapy is a method for treating cancer using drugs activated by light. A new compound, 5-aminolaevulinic acid (ALA), is a precursor of the active photosensitizer protoporphyrin IX (PpIX) and has fewer side-effects and much more transient phototoxicity than previous photosensitizers. Cell survival of ALA-mediated photodynamic therapy was measured in the J82 bladder cancer cell line, along with its mitomycin C-resistant counterpart J82/MMC. This demonstrated that mitomycin resistance is not cross-resistant to photodynamic therapy. There was also a suggestion that the mitomycin-resistant cells were more susceptible to photodynamic therapy than the parent cell line. Photodynamic therapy appeared to enhance the effect of mitomycin C, when mitomycin C was given first. This phenomenon was apparent for both drug-resistant and drug-sensitive cell lines. This suggests a possible role for combined mitomycin C and photodynamic therapy in superficial bladder tumours that have recurred despite intravesical cytotoxic drug treatment.

Aminolevulinic Acid↗

H2O2 generation during the redox cycle of mitomycin C and dna-bound mitomycin C.

Reduction of mitomycin C by NaBH4 or by NADPH in the presence of a cell extract followed by exposure to air results in the generation of H2O2. This phenomenon occurs not only with free mitomycin but also with mitomycin irreversibly bound to DNA. In view of these findings, the antibiotic activity of mitomycin was tested in two bacterial systems: a facultative aerobic bacterium grown in the presence or absence of oxygen and obligate anaerobic bacterium. No oxygen effect could be demonstrated in either case in the growth-inhibitory and bactericidal activity of the drug. Nevertheless, the H202 generating capacity of mitomycin-DNA complexes inside the nucleus may play a role in the drug-induced biological damage to the genetic material of cells.

Aerobiosis↗

Multicenter randomized trial comparing cisplatin-mitomycin-vinorelbine versus cisplatin-mitomycin-vindesine in advanced non-small cell lung cancer. 'Groupe Français de Pneumo-Cancérologie'.

The study was designed to evaluate the value of vinorelbine in a cisplatin-mitomycin-vinca alkaloid regimen for treatment of locally advanced or metastatic non-small cell lung cancer (NSCLC). A group of 227 patients with inoperable NSCLC in stage III (58%) or stage IV (42%) were included in this randomized multicenter trial comparing a reference regimen (VDS group, n = 113) cisplatin (120 mg/m2 on day 1, day 29 and day 71), mitomycin (8 mg/m2 on day 1, day 29 and day 71) and vindesine (3 mg/m2/week for 5 weeks and then every 2 weeks up to the 15th week) to a cisplatin-mitomycin-vinorelbine combination (VNB group, n = 114), with cisplatin and mitomycin at the same doses, and vinorelbine 25 mg/m2/week for 16 weeks. The objective response rate (evaluated at 17th week) was 17% in the VDS group and 25% in the VNB group (P = 0.15). Median survival was 33.4 weeks and 34.5 weeks in the VDS and VNB arms, respectively. Overall survival duration was not significantly different between the two arms (logrank test, P = 0.20) despite a trend to an increased survival in the VNB group. This essentially benefited the patients with stage III disease with a clear-cut lengthening of median (45.9 vs. 33.4 weeks) and 1 year survival (44.6% vs. 26.2%, P < 0.05) in favor of the VNB group. Nevertheless, there was no significant difference in overall survival (logrank, P = 0.13). Survival duration of the patients with stage IV disease was comparable in the two arms (logrank test, P = 0.90). Grade 3 or 4 neutropenia was found in 61% and 87% of the VDS and VNB groups, respectively (P < 0.01). Grade 2-4 peripheral neuropathy was observed in 23% of the patients in the VDS group and in 6% of the patients in the VNB group (P < 0.01). Replacement of vindesine by vinorelbine in a cisplatin-mitomycin-vinca alkaloid chemotherapeutic regimen did not lead to a significant improvement in objective response rate or in duration of survival. There was a reduction in neurotoxicity at the expense of an increased hematologic toxicity. However, for patients with stage III disease there was an increase in 1 year survival with the vinorelbine combination.

Aged↗

New potent mitomycin derivatives: synthesis and antitumor activity of 7,7-(ethylenedioxy)mitomycins.

A series of 6,7-dihydro-7,7-(ethylenedioxy)mitomycins was synthesized and evaluated for antitumor and anticellular activities. These compounds were prepared by basic treatment of 7-methoxymitomycins with ethylene glycol, and were structurally novel mitomycin derivatives containing a masked quinone moiety. 5,6-Enol or 6-chloro derivatives of 6,7-dihydro-7,7-(ethylenedioxy)mitomycins were also prepared and the (allyloxy)carbonyl group at the aziridine nitrogen has proved to be an efficient protecting group in chemical modification of mitomycins. Most of these mitomycin derivatives displayed potent antitumor activity against P388 leukemia in mice and anticellular activity against HeLa S3 cells.

Animals↗

A randomized trial with mitomycin-C/ifosfamide versus mitomycin-C/vindesine versus cisplatin/etoposide in advanced non-small-cell lung cancer.

192 evaluable patients with advanced inoperable non-small-cell lung cancer were treated with either mitomycin-C/ifosfamide (A), mitomycin-C/vindesine (B), or cisplatin/etoposide (C) in a prospective randomized trial. The response rates for each treatment arm were 30.0% (A), 22.7% (B), and 25% (C), respectively. There was no statistically significant difference (p = 0.4) between treatment arms. The median survival time was 27 weeks (A), 23 weeks (B), and 25 weeks (C), respectively. With regard to toxicity the combination mitomycin-C/vindesine was superior to treatment arms A and C. Nausea and vomiting (WHO 3 + 4) occurred only in 6.1% of the patients versus 43.3% of those treated with mitomycin-C/ifosfamide and 36.7% of those treated with cisplatin/etoposide. This difference is statistically highly significant (p = 0.0001). Because of its very low toxicity, especially for gastrointestinal symptoms, the combination mitomycin-C/vindesine was judged superior to the other combinations. None of these regimens, however, had a major impact on survival in advanced non-small-cell lung cancer.

Adult↗