Carminomycin I is an apoptosis inducer that targets the Golgi complex in clear cell renal carcinoma cells.

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.

[Anthracycline antibiotics and their derivatives--inhibitors of topoisomerase I].

The relationship between the structure of new semisynthetic derivatives of doxorubicin, daunorubicin, and carminomycin and their ability to inhibit topoisomerase 1 were studied. The new derivatives inhibit the activity of topoisomerase 1 at low concentrations, induce the death of K-562 leukemia cells in culture, and produce an antitumor effect in experimental animals with P388 leukemia.

Altered expression of topoisomerase IIalpha contributes to cross-resistant to etoposide K562/MX2 cell line by aberrant methylation.

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.

Carminomycin, 14-hydroxycarminomycin and its novel carbohydrate derivatives potently kill human tumor cells and their multidrug resistant variants.

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 from birch leaves]. / Tsitotoksicheskoe deistvie dammaranovykh triterpenoidov, vydelennykh iz list'ev berez.

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.

Antitumor activity of alpha fetoprotein and epidermal growth factor conjugates in vitro and in vivo.

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.

An investigation of the cytotoxicity of the morpholino anthracycline MX2 against glioma cells in vitro.

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.

Antitumor effect and peritumoral brain edema formation in relation to MX2, ACNU, and doxorubicin therapy: a comparative analysis using rodent models of gliomas.

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.

Structural requirements for the formation of anthracycline-DNA adducts.

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.

[Combination effect of hyperthermia and MX2 on cultured glioma cell lines].

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.

[The use of the nucleolar apparatus indices of the leukemic cells in patients with acute myeloblastic leukemia for the early detection of resistant clones]. / Ispol'zovanie nekotorykh pokazatelei iadryshkovogo apparata leikoznykh kletok bol'nykh ostrym mieloblastnym leikozom dlia rannego vyiavleniia rezistentnykh klonov.

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.

Induction of apoptosis in megakaryocytic leukemia cell lines by MX2, a morpholino anthracycline.

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.

Pharmacokinetics and pharmacodynamics of MX2 hydrochloride in patients with advanced malignant disease.

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.

[Antitumor effect of MX2, a new morpholino anthracycline against C6 glioma cells and its combination effect with photodynamic therapy in vitro].

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 antitumor effect of MX2, a new morpholino anthracycline, against malignant glioma cell lines and its subcellular distribution.

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.

Activity of the morpholino anthracycline 3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin (MX2) against human tumor colony-forming units in vitro.

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.

Cross resistance relevance of the chemical structure of different anthracyclines in multidrug resistant cells.

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.

Anthracycline metabolites from baumycin-producing Streptomyces sp. D788. II. New anthracycline metabolites produced by a blocked mutant strain RPM-5.

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.