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Clear cell renal cell carcinoma (CCRCC) evolves due to mutations in the Von Hippel-Lindau (VHL) tumor suppressor gene. Although the loss of VHL enables survival and proliferation of CCRCC cells, it is also expected to introduce vulnerabilities that may be exploited for therapeutics discovery. To this end, we developed a high-throughput screen to identify small molecules derived from plants, microorganisms, and marine organisms to which CCRCC cells are sensitive. Screening over 8,000 compounds using this approach, we report here the identification of the microbially derived compound carminomycin I (CA) as an effective inhibitor of VHL-defective (VHL(-/-)) CCRCC cell proliferation. CA also induced apoptosis in CCRCC cells by a mechanism independent of p53 or hypoxia-inducible factor 2. We found that P-glycoprotein (P-gp) sequestered CA within the Golgi complex. Interestingly, Golgi sequestration was critical for the antiproliferative effects of CA and P-gp inhibitors abrogated this activity. Furthermore, CA induced cleavage of the Golgi protein p115 and the translocation of its C-terminal fragment to the nucleus. Finally, examination of the activity of the VHL-interacting Golgi protein, endoplasmic reticulum-Golgi intermediate compartment, ERGIC-53 showed that VHL could mediate protection from CA in CCRCC cells. Our natural product-based screening approach has revealed the P-gp-mediated localization of anticancer compounds within the Golgi in CCRCC cells as a potential strategy of targeting VHL-deficient CCRCC cells., (© 2011 AACR.)

KRN 8602 (MX2) is a novel morpholino anthracycline derivative having the chemical structure 3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin hydrochloride. To investigate the mechanisms of resistance to MX2, we established an MX2-resistant phenotype (K562/MX2) of the human myelogeneous leukaemia cell line (K562/P), by continuously exposing a suspension culture to increasing concentrations of MX2. K562/MX2 cells were more resistant to MX2 than the parent cells, and also showed cross-resistance to etoposide and doxorubicin. Topoisomerase (Topo) IIalpha protein levels in K562/MX2 cells were lower of those in K562/P cells on immunoblot analysis and decreased expression of Topo IIalpha mRNA was seen in K562/MX2 cells. Topoisomerase II catalytic activity was also reduced in the nuclear extracts from K562/MX2 cells when compared with K562/P cells. Aberrant methylated CpG of Topo IIalpha gene was observed in K562/MX2 cells when compared with the parent line on methylation-specific restriction enzyme analysis. To overcome the drug resistance to MX2 and etoposide, we investigated treatment with 5-Aza-2'-deoxycytidine (5AZ), which is a demethylating agent, in K562/MX2 cells. 5-Aza-2'-deoxycytidine treatment increased Topo IIalpha mRNA expression in K562/MX2 cells, but not in K562/P cells, and increased the cytotoxicity of MX2 and etoposide. Methylated CpG was decreased in K562/MX2 cells after 5AZ treatment. We concluded that the mechanism of drug resistance to MX2 and etoposide in K562/MX2 cells might be the combination of decreased expression of Topo IIalpha gene and increased methylation, and that 5AZ could prove to be a novel treatment for etoposide-resistant cell lines, such as K562/MX2.

The new hydrophilic derivatives of 14-hydroxycarminomycin were obtained using 13-dimethyl ketal of 14-bromocarminomycin (6) as the starting compound. The reductive alkylation of 6 with melibiose or D-galactose followed by hydrolysis of the corresponding intermediate bromoketals 9 and 11 produced 3'-N-[-alpha-D-(galactopyranosyl-(1 --> 6)-O-D-1-desoxyglucit-1-yl]-14-hydroxycarminomycin (10) and 3'-N-(1-desoxy-D-galactit-1-yl)-14-hydroxycarminomycin (12), respectively. These novel derivatives 10 and 12 were less toxic than carminomycin or 14-hydroxycarminomycin for leukemia (K562) and breast carcinoma (MCF-7) cells. Importantly, carminomycin, 14-hydroxycarminomycin and compounds 10 and 12 were similarly active for wild type cells and their multidrug resistant (MDR) sublines, K562i/S9 and MCF-7Dox.

Cytotoxic activity of dammarane triterpenoids isolated from beach leaves was studied. These substances differ from the native ginseng genin (20(S)-protopanaxadiol) by the number, location, or configuration of OH-groups. Using fertilized egg cells of sea urchin Stronglyocentrotus intermedius we demonstrate that the orientation of C-3 OH-group has no effect on cytotoxic activity of triterpenoids as well as a higher activity of a triterpenoid with 3 alpha,12 beta-OH as compared to a C-3 ketone but lower activity as compared to a triterpenoid with 3 alpha,17 alpha-OH. Depending on the number of OH-groups the cytotoxic activity of triterpenoids decreases in the row: tetraol > pentaol > triol. Dammar-24-ene-3 alpha 2 beta,17 alpha,20(S)-tetraol (compound IV) is cytotoxic for the Ehrlich ascite carcinoma cells and this effect is additive to cytotoxic activity of anthracycline antibiotic carminomycin in vitro. Compound IV changes the permeability and microviscosity of the tumor cell membranes.

The potential antitumor effect of MX2, a new lipophilic morpholino anthracycline, was compared with those of ACNU or doxorubicin (DOX) using two different rodent glioma models. A mouse subcutaneous glioma model (203 glioma) was used to measure the effect of each drug on reducing the glioma size and a rat 9L intracerebral glioma model (9L glioma) was used to assess the antitumor effect on survival rate in a clinically similar fashion. Treatment with ACNU inhibited tumor growth by 94.6% (p < 0.0001) and complete regression of the tumor was observed in 3 of 25 (12.0%) of the ACNU-treated cases. Tumor growth was inhibited by 32.4% with DOX despite a tendency (p < 0.16) and by 59.4% with MX-2 (p < 0.001); neither of these drugs resulted in complete tumor regression. In the intracerebral glioma rats, only ACNU tended to ameliorate survival rate, but there was no statistical significance. These results suggest that ACNU has the most potent effect but MX2 can be an option for chemotherapy of malignant gliomas. Interestingly, all three drugs significantly elevated the brain water content on both the ipsilateral and contralateral sides of the tumor, although they did not induce brain edema in the normal rat brains. Careful management of brain edema might be required regardless of the drug used during chemotherapy to maximize the prognosis of glioma patients.

Conjugates of carminomycin (Cm) with alpha-fetoprotein (AFP) and epidermal growth factor (EGF) were prepared and their cytotoxic activities were studied in vitro. Both conjugates showed cytotoxic activity which exceeded that of free Cm in tumor cell cultures of MCF-7, SKOV3, QOS, P388 and B16 cells. The antitumor effects of the conjugates were studied in vivo in mice with subcutaneous tumors of B16 and P388 cells. The Cm-AFP and Cm-EGF conjugates inhibited tumor growth and noticeably increased the mean life span in experimental animals. Our results suggest that the therapeutic activity of Cm can be significantly enhanced by conjugation to AFP or EGF., (Copyright 2000 S. Karger AG, Basel.)

A series of anthracyclines (comprising carminomycins I, II and III, and barminomycin) were tested for their ability to react with DNA to form site-specific adducts using an in vitro transcription assay. The requirement for drug activation by formaldehyde was also assessed using a transcription assay and HPLC analysis of GC-containing oligonucleotide duplexes. In the absence of formaldehyde, barminomycin was the most reactive compound and carminomycin I the least reactive. The DNA sequence specificity of all anthracyclines was similar (the most intense binding sites being 5'-GC sequences), although barminomycin was the most selective for 5'-GC. Barminomycin adducts were the most stable at 37 degrees C (no loss in the 48 h time frame studied) while carminomycin II and III lesions were least stable (each with a half-life of approximately 4-5 h). These results are discussed collectively in terms of the requirement and contribution of structural elements of the anthracyclines for the formation of DNA adducts.

MX2 is a novel morpholino anthracycline reported to have lower systemic toxicity than other anthracyclines. It has similar antitumour activity to adriamycin and is cytotoxic towards multi-drug resistant cells and anthracycline sensitive sublines of human and murine tumour cells. In this study MX2 showed a marked cytocidal effect compared to M2, the most cytotoxically active metabolite, and the nitrosourea, BCNU, when 30 ng/ml of each drug was added to separate flasks of C6 glioma cells grown in monolayer. The colony formation of C6 glioma cells was markedly inhibited by MX2 in a dose dependent manner. The LD50 values for MX2, M2 and BCNU were 10.5 ng/ml, 15.8 ng/ml and 465 ng/ml respectively. MX2 is likely to be bound to the main plasma protein, albumin, and can also interact with the plasma lipoproteins, particularly high density lipoprotein. The results in this study strongly support the further investigation of MX2 as a potential chemotherapeutic agent against brain tumours.

MX2, a new lipophilic morpholino anthracycline, has been reported to have chemotherapeutic effects superior to those of adriamycin against murine and human glioma cells in vitro and in vivo. To assess the combination effect of MX2 and hyperthermia in vitro, the thermo-chemosensitivities of cultured human (U251MG and KC) and rat (C6 and 9L) glioma cell lines were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. The number of viable cells in each cell line was markedly and dose-dependently decreased by MX2 treatment, but the sensitivity of U251MG to MX2 was less than that of the other cell lines. The survival of each cell line was decreased with the hyperthermic treatment at 43 degrees C for 60 minutes. Combined treatment with MX2 and hyperthermia had an additive effect on cultured glioma cells when MX2 was added to the medium at a dose below 50 ng/ml. However, combined treatment indicated neither an additive nor a synergistic effect when the dose of MX2 was above 50 ng/ml. We conclude that MX2 may be clinically useful against malignant gliomas when administered alone or in combination with hyperthermia.

Changes were studied in the value for the nucleolar coefficient as were the percentage of large and compact nucleoli and numbers of Ag-NOR in the peripheral blood of patients with acute myeloblastic leukemia in order that resistant clones might be identified as early as possible. It has been ascertained that within 24 hours of the start of polychemotherapy "7 + 3" leukotic cells respond in different ways to the chemotherapeuticals employed depending on the outcome of the illness.

Leukemia with megakaryocytic involvement has a poor prognosis. MX2 is a new morpholino anthracycline that is effective against various leukemic cell lines. This study examined the antitumor activity of MX2 against human megakaryocytic cell lines, including CMK, CMK11-5, MEG-01, and UT-7, and investigated the role of apoptosis in the cytotoxicity of this drug. To quantify the extent of apoptosis induced by MX2, we used the in situ terminal deoxynucleotide transferase assay and the histone-associated DNA fragmentation assay. The cytotoxic effect of MX2 on CMK cells was reduced by various inhibitors of apoptosis. To our knowledge, this is the first report showing that apoptosis is involved in the killing of megakaryocytic cell lines by an antileukemic agent. We suggest that MX2 may be useful for the treatment of megakaryocytic leukemia.

The purpose of the present study was to investigate the pharmacokinetics and pharmacodynamics of the new morpholino anthracycline drug MX2. A total of 27 patients with advanced cancer participated in a dose-escalation study in the first cycle of treatment with drug given i.v. at doses of 10-50 mg/m2 (total dose 16.8-107.5 mg). The mean total systemic plasma clearance (CL) of MX2 was 2.98 +/- 1.68 l/min, the mean volume of distribution at steady state was 1460 +/- 749 l and mean elimination half-life was 10.8 +/- 5.1 h. The area under the plasma concentration-time curve (AUC) of MX2 was linearly related to the dose per kilogram and the dose per body surface area (r2 = 0.43, P < 0.01 and r2 = 0.44, P < 0.01, respectively). CL did not correlate with total body weight, lean body mass or body surface area. The mean elimination half-lives of the metabolites M1, M2, M3 and M4 were 11.8 +/- 5.0, 21.9 +/- 11.8, 19.0 +/- 11.3 and 12.3 +/- 6.3 h, respectively. The fractional Emax model produced a much better fit to the relative nadir neutrophil count versus dose data (r2 = 0.42) than to the relative nadir neutrophil count versus AUC or peak concentration (Cmax) data (r2 = 0.15 and 0.09, respectively). There seemed to be a threshold dose of about 65 mg of MX2 at or above which a large proportion of patients had a nadir neutrophil count of less than 0.5 x 10(9)/l. This study shows that the pharmacokinetics of MX2 are similar to those of other anthracyclines. With other anthracyclines the degree of myelosuppression seems to depend more on the AUC and Cmax than on the delivered dose; however, with MX2 the degree of myelosuppression depends more on the dose given than on drug exposure expressed as the AUC or Cmax.

MX2, a new lipophilic morpholino anthracycline, has been reported to have superior chemotherapeutic effects to adriamycin against murine and human tumor cells. In this study the chemotherapeutic effect of MX2 against C6 glioma cells was examined as well as the photocytotoxicity of MX2 and the combination effect of MX2 and photodynamic therapy (PDT) in vitro. Colony formation is inhibited even with only 2 hour treatment with MX2 in a dose-dependent manner. In this colony forming efficiency assay the drug concentration required for 50% inhibition of colony formation for C6 glioma cells was 24.0 +/- 4.5 ng/ml. Mild photocytotoxicity of MX2 against C6 glioma cells was observed at a high concentration (100 ng/ml) of MX2 following exposure to white light but not red light. In combination, MX2 and the photosensitizer haematoporphyrin derivative (HpD) exhibited an additive cytotoxic effect against C6 glioma cells when the cells were treated with MX2 either immediately after red light illumination following incubation with HpD or at an interval of 24 hours before incubation with HpD. We conclude that MX2 may be clinically useful against malignant glioma alone, and in combination with other therapies such as PDT.

The chemotherapeutic effect of MX2 (3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin), a new lipophilic morpholino anthracycline, against rat C6 and human T98G glioma cells, was examined in vitro and in vivo. The subcellular distribution of MX2 was also studied. The drug concentrations of MX2 required for the 50% inhibition of cell growth (IC50) for C6 and T98G cells were 25.5 +/- 1.3 ng/ml and 70.6 +/- 6.8 ng/ml, respectively, which were much lower than the IC50 values for nimustine (ACNU). A C6 subline resistant to ACNU, C6/ACNU, was established by continuous exposure to graded concentrations of ACNU. The IC50 of MX2 for C6/ACNU was 28.3 +/- 2.2 ng/ml, indicating no cross-resistance to MX2. In the rats bearing the intracerebral C6 tumors, the life span was increased by about 40 to 100% after intravenous administration of MX2 at doses ranging from 1 to 3 mg/kg of body weight. Confocal laser scanning microscopy demonstrated visually the good accumulation of MX2 in the implanted intracerebral C6 tumors, as well as its predominant distribution in the cytoplasm over the nucleus in both cell lines in vitro. Ultrastructural studies also demonstrated the cytotoxic effects of MX2 against glioma cells. Our results suggest that MX2 may be a useful chemotherapeutic agent in the treatment of malignant gliomas and that confocal laser scanning microscopy is useful for the study of the cellular pharmacokinetics of anthracycline derivatives, such as MX2.

In several preclinical systems, the morpholino anthracycline MX2 has greater antitumor activity than doxorubicin, is less cardiotoxic, and is effective against multidrug resistant cancer cells. We used a human tumor soft-agar cloning assay to test the cytotoxicity of MX2 against single cell suspensions from freshly obtained human tumors. Tumor cells were exposed to MX2 at 0.05 and 0.5 micrograms/ml either for 1 hour (2-1 specimens; 77 [38%] assessable) or continuously (231 specimens; 91 [39%] assessable). Superior antitumor activity was observed with continuous exposure (19% in vitro response at 0.05 micrograms/ml and 69% at 0.5 micrograms/ml) than with 1-hour exposure (1.3% at 0.05 micrograms/ml and 12% at 0.5 micrograms/ml). Activity was seen against all types of cancer tested including renal (91%), melanoma (88%), ovarian (73%), breast (71%) and non-small-cell lung (67%) cancer at a MX2 concentration of 0.5 micrograms/ml after continuous exposure. If appropriate plasma levels can be achieved in patients, MX2 could have significant clinical activity with those tumors.

Positively charged doxorubicin (DOX) and non-positively charged anthracyclines, aclarubicin (ACR) and morpholino-carminomycin (KRN 8602), have been investigated with respect to pharmacological parameters, cytotoxicity, DNA damage and repair in DOX-sensitive and -resistant murine and human cells. Friend leukemia cells (FLC) resistant to high concentrations of doxorubicin (DOX-RFLC3) or daunorubicin (DNR-RFLC3) (1771 and 1543 fold resistance respectively) express less than 10 fold resistance to aclarubicin (ACR). In these cells, the intracellular accumulation of ACR is similar in sensitive and resistant cells. Resistance to ACR was not observed in either DOX-RFLC1 or DNR1 with a lower level of resistance (27 fold). Increased expression of a 170,000-dalton surface antigen (gp-170) was found to be correlated with the level of resistance. However, when the selective agent in ACR, despite the low level of resistance (2.8 fold) both high expression of gp 170 and resistance to DOX (77 fold) or DNR (62 fold) are observed. It is assumed therefore that induction of multidrug resistance phenotype can be achieved by compounds which do not display cross resistance with DOX or DNR. Reduced levels or absence of cross-resistance can be related to the electrical charge of the compound. This assumption is supported by further studies on DOX-sensitive or -resistant human K562 cells exposed to another non-positively charged anthracycline, KRN 8602. In the continuous presence of drug, K562/DOX were less resistant to KRN 8602 (2.9 fold) than to DOX (31 fold). After short time exposure followed by growth in drug-free medium, absence of cross-resistance to KRN 8602 has been observed in K562/DOX. Furthermore, accumulation experiments showed that high intracellular drug concentrations were rapidly achieved (within 15 min) in both DOX-sensitive and -resistant cells. In cells exposed to DOX, DNA single-strand break (DNA-SSBs) frequencies were related to time and drug concentration while those produced by KRN 8602 or ACR were maximal after short time incubation. DNA-SSBs produced by these anthracyclines are not repaired when cells are incubated in drug free medium. In DOX resistant cells, DNA-SSBs produced by DOX were repaired whereas those produced by ACR or KRN 8602 were not. It is suggested, therefore, that absence of cross resistance to various anthracyclines is related to differences in the chemical electrical charge, which may influence drug accumulation and DNA repair in resistant cells.

A daunorubicin-blocked mutant strain RPM-5 derived from a new baumycin-producing Streptomyces sp. D788 accumulated a major precursor metabolite D788-1 (10-carboxyl-13-deoxocarminomycin) and nine minor metabolites in the culture broth. Five among them were new with a substituent at C-10 or the altered side chains at C-9. Isolation, purification and identification of all anthracycline metabolites produced by strain RPM-5 are described with their antitumor activities against L1210 cells.

In an attempt to predict the clinical activity of newly developed anthracycline analogues, ME2303, KRN8602, and SM5887 in the treatment of lung cancer, we compared antitumor activity of these drugs with that of adriamycin, using six human lung cancer cell lines and two drug-resistant human lung cancer sublines. Taking the pharmacokinetic data into consideration, we evaluated the relative antitumor activity: the ratio of area under the concentration-time curve of each drug to the 50% inhibitory concentration of the drug. Regarding this ratio, ME2303 was more potent than adriamycin, SM5887, and KRN8602. Cross-resistance of the new analogues to adriamycin was investigated using an adriamycin-resistant small cell lung cancer subline, SBC-3/ADM100 and an etoposide-resistant subline, SBC-3/ETP. SBC-3/ADM100 being 106-fold more resistant to adriamycin than the parent SBC-3 showed less resistance to the analogues: 1.80-fold to KRN8602, 3.80-fold to SM5887, and 8.60-fold to ME2303. SBC-3/ETP which was 52.1-fold more resistant to etoposide and 39.5-fold more resistant to adriamycin were also less resistant to the new analogues: 3.27-fold to KRN8602, 9.07-fold to SM5887, and 17.3-fold to ME2303. In conclusion, ME2303 was found to be the most potent agent among drugs tested for the treatment of lung cancer, and KRN8602 can be expected to be beneficial for the treatment of drug-resistant small cell lung cancer.

We previously reported that MX2, a new morpholino anthracycline, showed marked effects on pleiotropic drug-resistant sublines of murine P388 leukemia in vivo as well as in vitro. In this study we examine the in vitro cytotoxicity against pleiotropic drug-resistant sublines of human tumor cell lines. MX2 was effective against multidrug-resistant sublines of four human tumor cell lines; these cells, having a 4.8- to 200-fold cross-resistance to Adriamycin (ADM) showed only a 0.7- to 2.3-fold resistance to MX2 compared with the sensitive cells. To elucidate the mechanism by which MX2 overcomes multidrug resistance, the intracellular pharmacology of MX2 in human myelogenous leukemia K562 and its ADM-resistant subline (K562/ADM) was examined. Both K562 and K562/ADM cells accumulated MX2 more easily than ADM, and the intracellular accumulation of MX2 attained a steady state in both cell lines within 30 min of incubation at 37 degrees C. The amount of MX2 that accumulated in K562/ADM at a steady state was only 1.3 times lower than that in K562. However, ADM was accumulated slowly in both cell lines compared with MX2, and the intercellular concentration reached a steady state in K562/ADM after 90 min of incubation and in K562 after more than 120 min. K562/ADM cells accumulated a 3.3-fold lower concentration of ADM than K562 after 120 min of exposure. The steady-state concentration of ADM in K562/ADM was 8.3 times lower than that of MX2. In addition, greater than 70% of MX2 was retained in both cell lines after 150 min of incubation in the absence of this drug. Verapamil, a calcium antagonist, hardly augmented the cytotoxicity of MX2 against K562/ADM, and no distinct effect of this drug on both the time course and the maximal level of accumulation of MX2 was observed. Interestingly, MX2 effectively inhibited ATP/Mg2(+)-dependent [3H]vincristine binding to K562/ADM membrane preparations, indicating that MX2 could be transported outside the cell by an active efflux pump. The high intracellular accumulation and retention of MX2 in K562/ADM through the rapid influx of the drug into the cells may be one of the reasons why MX2 circumvents pleiotropic drug resistance.

The mechanism of action of 3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin (MX2) was examined in a human leukemia cell line (K562) and its Adriamycin (ADM)-resistant subline (K562/ADM). ADM and MX2 showed an equivalent antitumor effect against K562. K562/ADM was highly resistant to ADM. In cellular pharmacokinetic studies, MX2 showed faster and greater influx than did ADM in both K562 and K562/ADM. The efflux of ADM was rapid in K562/ADM but not in K562. On the other hand, the efflux of MX2 was rapid in both cell lines. The formation of DNA single-strand breaks and double-strand breaks by ADM was significantly lower in K562/ADM than K562. On the other hand, formation of those breaks by MX2 was not decreased. Although some of the DNA breaks induced by MX2 were resealed, there was no difference in the degree of resealing in K562 and K562/ADM cells. On the other hand, most of the small number of DNA breaks in K562/ADM induced by ADM were resealed. The topoisomerase II activity in K562 and K562/ADM was not significantly different. It is concluded that MX2 conquers multidrug resistance by rapid influx following a higher frequency of formation of DNA single- and double-strand breaks in K562/ADM cells.

The sensitivity of three human fibroblast lines, trisomic with respect to chromosome 21, to an anthracycline antibiotic carminomycin was compared with that of a normal fibroblast line using a 51Cr release assay. It was found that for an intermediate antibiotic concentration (10 microM) the sensitivity of trisomic fibroblasts, of increased content of Cu,Zn-superoxide dismutase was lower. These results suggest a role for superoxide-mediated membrane damage in the cytotoxic action of anthracycline antibiotics.

Inhibition of DNA synthesis by rubomycin (daunorubicin), carminomycin and doxorubicin in the spleen, liver, kidneys and heart was studied on mice. The antibiotics were administered intravenously in a dose of 0.3 LD50. The inhibition level was estimated by incorporation of 3H-thymidine. The time courses of DNA synthesis inhibition by daunorubicin, carminomycin and doxorubicin markedly differed, whereas the patterns of their inhibition curves for all the organs were close. The maximum inhibition of DNA synthesis by carminomycin was observed in 6 hours. After that period it gradually restored. Doxorubicin induced the maximum inhibition of DNA synthesis in 24-48 hours after its administration. Daunorubicin induced two maxima in inhibition of DNA synthesis i. e. in 6 and 48 hours. Definite correlation between the levels of DNA synthesis inhibition by the antibiotics and their toxic action was shown.

The cytotoxic effect of daunorubicin, carminomycin, idarubicin and the major metabolite of idarubicin in man, 4-demethoxydaunorubicinol, was investigated in a human normal progenitor myeloid stem cell assay and in a human tumor stem cell assay. Against normal myeloid progenitor cells, idarubicin and carminomycin were equally potent; both agents were significantly (P less than or equal to 0.01) more potent than daunorubicin. Idarubicin was approx. 2.5 times more potent than 4-demethoxydaunorubicinol. Against malignant tumor cells, 50% cell kill after exposure to idarubicin was observed in four out 24 samples; this inhibition occurred at a drug concentration of 0.1 micrograms/ml. Two of the samples sensitive to idarubicin were also sensitive to 4-demethoxydaunorubicinol at a concentration of 0.1 micrograms/ml. Overall, idarubicin was active against two out of six ovarian carcinomas and against one out of three breast carcinomas. Our data confirm that 4-demethoxydaunorubicinol may play a role in the biological activity of idarubicin.

Carminomycin was shown to inhibit the development of both the DNA-containing variolovaccine virus and the RNA-containing grippe virus in chick embryos. Comparison of the effects of rubomycin, carminomycin, 14-oxy-carminomycin and carminomycin complex with bovine serum albumin in experiments with chick embryos showed that the inhibitory effect of carminomycin and its derivatives on the development of the grippe virus was much higher than that of rubomycin. The carminomycin derivatives proved to be much more active in this respect than the initial antibiotic. Carminomycin and its derivatives had a therapeutic effect on mice with experimental grippe pneumonia also on their oral use.

Treatment of di-O-acetyl-2-deoxy-L-fucopyranosyl bromide with carminomycinone and epsilon-pyrromycinone in the presence of mercuric bromide and mercuric cyanide afforded 3',4'-diO-acetyl-2'-deoxy-L-fucopyranosylcarminomycinone and -epsilon-pyrromycinone. Similarly, when di-O-acetyl-2-deoxy-D-erythrho-pentopyranosyl chloride was treated with daunomycinone, carminomycinone and epsilon-pyrromycinone, the di-O-acetyl derivatives of the anthracyclinone glycosides were obtained. Deacetylation of the previous acetates with sodium methoxide afforded 2'-deoxy-L-fucopyranosylcarminomycinone and -epsilon-pyrromycinone, as well as 2'-deoxy-D-erythro-pentopyranosyldaunomycinone, -carminomycinone, and -epsilon-pyrromycinone. 2'-Deoxy-L-fucopyranosylcarminomycinone was found to be more active than carminomycin at higher dosages on L1210.

A simple procedure for preparation of tritiated anthracycline antibiotics, such as rubomycin and carminomycin is described. The method is based on isotope exchange with tritiated water at 100 degrees C. The specific activity of the preparations is several hundreds decays a minute per 1 microgram. The stability of the antibiotic label in aqueous solutions at various pH values was determined. At pH 7.2 and a temperature of 37 degrees C the loss of the tritium by the end of the 1st, 2nd, 3rd, 4th and 7th day amounted to 7.1, 11, 14, 19, and 24 per cent, respectively. It is concluded tht tritiated antibiotics prepared with the method of tritiated water exchange may be used in biomedical investigations.

The effect of various concentrations of antitumor antibiotics, such as carminomycin, rubomycin, adriamycin, mitomycin C and bruneomycin on transduction of erythromycin resistance from the donor strain 8325 P II/de of Staph, aureus to the recipient strain 8325-I in different transduction systems was studied. It was shown that the above antibiotics inhibited the transduction in the systems with constant presence of the drugs. Preliminary treatment of the recipient cells with the drugs in the subbacteriostatic doses did not decrease the transfer frequency. The preliminary treatment of the donor cells resulted in an increase in the phase titer and the transfer frequency in the "preliminary-treated donor + recipient" system.

A new antitumor antibiotic, 13-deoxycarminomycin, has been isolated from the anthracycline complex produced by Streptomyces peucetius var. carminatus (ATCC 31502), a biochemical mutant of Streptomyces peucetius var. caesius, the doxorubicin-producing microorganism. The new anthracycline, showing antibacterial and cytotoxic activity in vitro, was found active against P-388 murine leukemia.

Carminomycin (CMN) was administered i.v. to 44 patients with a variety of nonhematological cancers every 4 weeks at doses of 15, 20, 22.5, and 25 mg/sq m. Granulocytopenia was the dose-limiting toxicity. The median granulocyte count for previously untreated patients receiving 22.5 mg/sq m was 0.962 cells/microliters, and for previously treated patients receiving 20 mg/sq m it was 0.420 cell/microliters. Moderate to severe phlebitis was associated with drug administration in 50% of cases. Nausea, vomiting, and alopecia were mild. Three of nine patients who received a total CMN dose of greater than or equal to 100 mg/sq m (mean, 132 mg/sq m) developed unexplained decreases in radionuclide cardiac ejection fraction, with one patient developing decreased QRS amplitude and congestive heart failure at a total dose of 160 mg/sq m. CMN is rapidly metabolized to carminomycinol. The elimination half-lives of CMN and carminomycinol are 6 to 10 and 50 hr, respectively. CMN was found to be a more potent inhibitor of human granulocyte-macrophage colony-forming units than was carminomycinol. Objective partial responses were seen in two of seven previously untreated patients with non-small cell lung cancer and one of three patients with squamous cell carcinoma of the head and neck previously untreated with chemotherapy.

General toxic and myeloinhibitory effects of some antitumor antibiotics, such as rubomycin, olivomycin, bruneomycin and karminomycin administered intraperitoneally in a single LD50 to mice were studied. It was found that the general toxicity of bruneomycin and karminomycin was almost the same and 5 to 8 times higher than that of rubomycin and olivomycin. The use of the above antibiotics resulted in definite shifts in the blood systems of healthy mice. The most significant suppression of hemopoesis accompanied by a pronounced depression of the number of the myelocariocytes was observed after the use of olivomycin. The effect of karminomycin was characterized by suppression of erythro-, myelo- and lymphopoesis and depression of the number of the granulocytes and lymphocytes of the blood. Bruneomycin and rubomycin had a short-time myeloinhibitory effect. The erythroid cords of the bone marrow proved to be most sensitive to the inhibitory effect of the antibiotics. However, inhibition of the erythropoesis accompanied by deep reticulocytopenia did not induce the respective depression of the erythrocyte number. The lymphoid cords was in the 2nd place by its sensitivity to the antibiotics and the myeloid and megocariocytal cords were in the 3rd and the 4th places respectively. Complete reduction of hemopoesis in the animals was observed by the 10th day of the drugs use.

Inhibition of DNA synthesis in the liver, kidneys, spleen and heart of mice after intravenous administration of 0.1 and 0.3 LD50 of semisynthetic derivatives of rubomycin (daunorubicin) and carminomycin was studied. The level of DNA synthesis inhibition was estimated by a decrease in incorporation of (methyl-3H) thymidine. Under the action of 13-trebutoxycarbonyl hydrazone and 14-salicyloiloxy derivatives of rubomycin and carminomycin maximum inhibition of DNA synthesis was reached later while its recovery started earlier as compared to the initial antibiotics.

Yeast mutants with distorted cell membranes, which are selectively inhibited by anticancer antibiotics and are not affected by antibacterial antibiotics, could be of considerable interest as test organisms. They could be used for the isolation of active antitumor substances from complex mixtures of natural compounds.

The optical properties of the mesophases modeling the condensed state of cell DNA molecules formed from the complexes of 7-anthracycline antibiotics with double-stranded low-molecular DNA and polynucleotides were studied. The parameters of the antibiotic binding to the DNA during formation of the mesophases (0.3 M NaCl, 150 mg/ml of polyethylene glycol) are presented. It was found that the CD mesophase spectrum formed from the complex of DNA-antibiotic was characterized by the presence of intensive negative bands in the region of absorption of the chromophores of both DNA and antibiotic. This is indicative of regular spiral organization of the DNA mesophase. Binding of the antibiotic to DNA and polynucleotides was accompanied by changing of the band negative mark (at definite levels of the DNA molecule filling with the antibiotic) in the CD mesophase spectrum to the positive one. It was shown that with respect to the mesophases formed from the complexes of DNA with iremycin and aclacinomycin A no changing in the band marks was observed. Consequently, antibiotics may be conditionally divided into 2 groups. The antibiotics of the first group induce changes in the spin direction of the DNA mesophase, while the antibiotics of the second group had no such effect. It was demonstrated that antibiotic binding with the AT-rich sequences induce more pronounced changes in the mesophase properties than that with the GC-rich sequences. Possible causes of the mark changing in the spin of the DNA mesophase during the DNA binding with antharcyclines are discussed. Biological significance of the phenomenon is still unclear.

N-Monoethyl derivatives of carminomycin, rubomycin, 13-dihydrocarminomycin and 13-dihydrorubomycin were synthesized by condensation of their amino groups with acetic aldehyde in the presence of sodium boron hydride. The respective N,N-diethyl derivatives of the antibiotics were formed as by-products of the reaction. New compounds such as N-ethylcarminomycin, N,N-diethylcarminomycin, N-ethyl-13-dihydrocarminomycin, N,N-diethyl-13-dihydrocarminomycin, N-ethylrubomycin and N-ethyl-13-dihydrorubomycin were synthesized. Antibacterial activity of N-ethyl- and N,N-diethyl derivatives of carminomycin and rubomycin determined with the use of Bac. mycoides as the test microbe was 40-50 per cent and that of N-ethyl- and N,N-diethyl-13-dihydro-derivatives was 15-30 per cent of the activity of the respective antibiotics, carminomycin and rubomycin.

A new antibiotic complex has been obtained from the cultures of an actinomycete, strain FA-1180, isolated from a soil sample collected at lake side of Biwa in Japan. On the basis of taxonomic studies the producing microorganism is designated as Actinomadura roseoviolacea var. biwakoensis nov. var. The antibiotic complex belongs to the class of anthracycline glycoside antibiotics. All components form deep red fine needles on crystallization; components are named rubeomycin A, A1, B and B1. These components exhibit activity against Gram-positive bacteria as well as Yoshida sarcoma cell in vitro. These components are also effective on P388 leukemia.

Autoradiographic investigations with the use of 3H-thymidine were performed on 140 noninbred albino rats. The fate of the label in the cells of the myeloid series was followed in the experimental and control groups. The animals of the experimental group were treated with carminomycin in the LD50 30 minutes after injecion of 3H-thymidine. The mitotic cycle of the nondifferentiated cells and promyelocytes + myelocytes in the control animals was equal to 24 hours, the period and rate of the metamyelocyte maturation being 10 hours and 0.81 per cent/hour respectively. The mitotic cycle of the nondifferentiated cells and promyelocytes + myelocytes during the first division after carminomycin administration increased up to 48 hours due to the block of G2-period, the period and rate of the metamyelocyte maturation being 18 hours and 0.43 per cent/hour respectively. The myelotoxic effect of carminomycin was due to the damage of the dividing cells in G2-period of the mitotic cycle, decreased rate of differentiation and death of the cells after or during the first and second divisions.

Acute toxicity of the components of the carminomycin complex after intravenous administration to albino mice increased as follows. I less than II less than III. Component II induced a decrease in all the indices of the bone marrow and peripheral blood of the animals. It was most pronounced in dogs. The dogs died after administration of component II in the lethal doses as a result of the bone marrow aplasia. The indices of the functional state of the liver and kidneys in the animals after administration of components I and II changed slightly. Component III administered repeatedly to rabbits even in low doses induced significant impairments in the function of the liver and kidneys. Component II differed from component I by more pronounced cardiotoxicity. On the basis of the experimental data and the results published earlier component I is recommended for clinical trials as the least toxic one.

14-Bromocarminomycin and 14-bromorubomycin were treated with alkali metal salts and nitrogen heterocycles to obtain 14-acetoxycarminomycin, 14-octamoylhydroxycarminomycin, 14-salicyloylhydroxycarminomycin, 14-salicyloylhydroxyrubomycin, 14-chinaldinoylhydroxyrubomycin and rubomycin 14-N-phthalimide, rubomycin 14-N-pyridinium bromide and 14-N-imidazolylrubomycin. It was shown that the reaction rate of the nucleophilic substitution in the acetone medium could be increased with the use of crown ethers of sodium iodide. Under such conditions 14-iodinecarminomycin and 14-iodinerubomycin, two intermediate products, partially reduced to the initial antibiotics, i.e. carminomycin and rubomycin. 14-Acetoxycarminomycin had the highest activity against Bac. mycoides, used as a test microbe. It amounted to 50 per cent, while the activity of the other derivatives did not exceed 25 per cent of the activity of the initial antibiotics.

In our experimental work we intended to study the effect of certain anthracycline antibiotics, like Adriamycin, Daunomycin, Carminomycin on the RNA dependent DNA polymerase, i.e. reverse transcriptase (RT) system. Over the direct effect on the RT our aim was to find out the rate of selectivity of above antibiotics on the RT. For doing this we compared the above effects to those found on natural nucleic acid polymerases. These experiments were confirmed using synthetic polynucleotid template poly(rA)n(dT)12-18 for the Rauscher RT enzyme and poly(dA)n . poly(dT)n for E. coli DNA polymerase I. In our work we have shown that Carminomycin, in contrast to Adriamycin and Daunomycin, possesses a highly specific inhibitory effect on the RT enzyme system.

A comparative mutagenic effect of karminomycin and rubomycin in LD50 on the cells of the rat bone marrow (71 animals) was studied. It was found that karminomycin had a higher and more prolonged mutagenic effect than rubomycin. Both antibiotics induced mainly chromatin deletions and not so frequent reconstructions. They are probably identical with respect to their mechanism of action on chromosomes.

A comparative study on the effects of antitumour antibiotics of the anthracycline group (rubomycin, carminomycin and adriamycin) on respiration and oxidative phosphorylation in liver mitochondria in various metabolic states has been carried out for the first time. It was shown that the antibiotics under study cause partial inhibition of mitochondrial state 3 respiration, which is eliminated by an uncoupler. Treatment of liver mitochondria with the antibiotics decreases the ADP/O and respiratory control values and stimulates state 4 respiration. The latter is partly inhibited by oligomycin. The uncoupled respiration is decelerated in the presence of the antibiotics. Under these conditions the oxidation of succinate is inhibited by lower concentrations of the antibiotics than that of NAD+-dependent substrates. It was shown that the maximal activity is exerted by the most polar agent carminomycin, while the hydrophobic rubomycin is the least active. The experimental results are discussed in terms of the toxic effect of antitumour antibiotics.