AIMTo compare two methods, the total radioactivity assay (RA method) and the radioactivity assay after separation with high performance liquid chromatography (HPLC-RA method).

METHODS125I-Lidamycin was prepared by Iodogen method and separated by size exclusive high performance liquid chromatography. The pharmacokinetic parameters of lidamycin were assayed by two methods after intravenous injection to mice at the dose of 100 microg x kg(-1), and compared by statistical analysis.

RESULTSThe pharmacokinetic parameters (Vd, T1/2alpha, T1/2beta, K21, K10, K12, AUC and CL) showed significant difference between the two methods (P < 0.05).

CONCLUSIONThe HPLC-RA method was better than the RA method to determine unchanged 125I-lidamycin.

Aminoglycosides ; blood ; pharmacokinetics ; Animals ; Antibiotics, Antineoplastic ; blood ; pharmacokinetics ; Area Under Curve ; Chromatography, High Pressure Liquid ; methods ; Enediynes ; Female ; Iodine Radioisotopes ; Isotope Labeling ; Male ; Mice ; Sensitivity and Specificity

Lidamycin (LDM) is a potent antitumor antibiotic. Previous studies have shown that LDM could inhibit proliferation and migration in endothelial cells. In the present report, the effect of LDM on angiogenesis of zebrafish embryo was studied. The results showed that treatment of zebrafish embryos with LDM resulted in significant inhibition of angiogenesis. Morphological observation, quantitative endogenous alkaline phosphatase (EAP) assay, alkaline phosphatase staining, and transgenic zebrafish assay were performed to evaluate vascular development defects in zebrafish. The results indicated that after the zebrafish embryos were exposed to LDM, angiogenesis defects of zebrafish embryos were observed, including pericardial edema, reduced numbers of circulating red blood cells, suppression of zebrafish vessel growth, and absences of SIV (subintestinal vein). The expression of VEGF was detected by RT-PCR assay, quantitative reverse transcriptase real-time PCR (qRT-PCR) assay and Western blotting analysis. The results revealed that LDM could inhibit the expression of VEGF protein, while the expression of mRNA was not significantly affected. The study suggests that LDM could inhibit the zebrafish embryo angiogenesis by down-regulation ofVEGF expression.
Aminoglycosides ; pharmacology ; Animals ; Animals, Genetically Modified ; embryology ; genetics ; physiology ; Antibiotics, Antineoplastic ; pharmacology ; Down-Regulation ; Embryo, Nonmammalian ; drug effects ; Enediynes ; pharmacology ; Neovascularization, Physiologic ; drug effects ; genetics ; RNA, Messenger ; metabolism ; Vascular Endothelial Growth Factor A ; genetics ; metabolism ; Zebrafish ; embryology ; genetics ; physiology

This study is to investigate the binding capability of lidamycin apoprotein (LDP), an enediyne-associated apoprotein of the chromoprotein antitumor antibiotic family, to human breast cancer and normal tissues, the correlation of LDP binding capability to human breast cancer tissues and the expression of tumor therapeutic targets such as VEGF and HER2. In this study, the binding capability of LDP to human breast cancer tissues was detected with tissue microarray. The correlation study of LDP binding capability to human breast tumor tissues and relevant therapeutic targets was performed on breast cancer tissue microarrays. Immunocytochemical examination was used to detect the binding capability of LDP to human breast carcinoma MCF-7 cells. As a result, tissue microarray showed that LDP staining of 73.2% (30/41) of breast cancer tissues was positive, whereas that of 48.3% (15/31) of the adjacent normal breast specimens was positive. The difference between the tumor and normal samples was significant (Chi2 = 4.63, P < 0.05). LDP immunoreactivity in breast cancer correlated significantly with the overexpression of VEGF and HER2 (P < 0.001 and < 0.01, r = 0.389 and 0.287, respectively). Determined with confocal immunofluorescent analysis, LDP showed the binding capability to mammary carcinoma MCF-7 cells. It is demonstrated that LDP can bind to human breast cancer tissues and there is significant difference between the breast cancer tissues and the corresponding normal tissues. Notably, the binding reactivity shows positive correlation with the expression of VEGF and HER2 in breast carcinoma tissues. The results imply that LDP may have a potential use as targeting drug carrier in the research and development of new anticancer therapeutics. This study may provide reference for drug combination of LDM and other therapeutic agents.
Aminoglycosides ; metabolism ; Antibiotics, Antineoplastic ; metabolism ; Apoproteins ; metabolism ; Breast Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Enediynes ; metabolism ; Female ; Humans ; Protein Binding ; Receptor, ErbB-2 ; metabolism ; Tissue Array Analysis ; methods ; Vascular Endothelial Growth Factor A ; metabolism

This paper is to report the study of the metabolism of lidamycin in vitro including in plasma and microsomes to guide clinical therapy. Lidamycin was quantified by detecting its active ingredient using HPLC-MS/MS. The metabolic stability of lidamycin in rat, Beagle dog, monkey and human plasma and liver microsomes, and its inhibition to cytochrome P450 isoforms in human liver microsomes were studied. Results showed that lidamycin was metabolized in the four species of plasma, and the sequence of metabolic rates in plasma were in rat > in dog > in human > in monkey. But among the four species of liver microsomes, lidamycin was metabolized only in monkey liver microsomes. There was almost no inhibition to cytochrome P450 isoforms at the concentrations of between 0.0005 and 10 ng x mL(-1). Therefore, the property of lidamycin metabolism in human is similar with that in dog, and metabolism of other drugs would not be decreased by cytochrome P450 as used along with lidamycin in clinic.
Aminoglycosides ; blood ; metabolism ; Animals ; Antibiotics, Antineoplastic ; blood ; metabolism ; Chromatography, High Pressure Liquid ; Cytochrome P-450 CYP1A2 ; metabolism ; Cytochrome P-450 Enzyme System ; metabolism ; Dogs ; Enediynes ; blood ; metabolism ; Enzyme Activation ; Humans ; Macaca ; Microsomes, Liver ; metabolism ; Rats ; Tandem Mass Spectrometry

AIMTo investigate the synergetic effect and the mechanism of antitumor action of the antibiotic lidamycin in combination with cisplatin in vitro.

METHODSCytotoxicity of the drugs was measured by clonogenic assay. Chromatin condensation was observed by co-staining with fluorescent dyes, Hoechst 33342 and propidium iodide. Apoptotic sub-G1 was detected by flow cytometry and DNA ladder was observed using agarose gel electrophoresis. Bcl-2 protein level was detected by Western blot assay.

RESULTSBy using clonogenic assay, lidamycin in combination with cisplatin was found to have synergetic effects on the proliferation of human hepatoma BEL-7402 cells. The data showed that BEL-7402 cells treated with cisplatin and lidamycin in combination produced internucleosomal DNA fragmentation analysed by agarose gel electrophoresis. The results of flow cytometry showed that cisplatin and lidamycin administrated in combination showed no obvious change in G1 phase distribution compared with single treatment. However, this combination reduced the S phase arrest and reversed the reduction of G2/M phase induced by single treatment. The results also showed that there was 11.3% or 9.37% of cells undergoing apoptosis in BEL-7402 cells treated with cisplatin or lidamycin, respectively, while it showed 32.4% of apoptotic cells in combination treatment. Cisplatin, lidamycin and combination of cisplatin and lidamycin was shown to induce typical chromatin condensation in BEL-7402 cells. The study showed that 0.5 mumol.L-1 cisplatin or 1 x 10(-4) mumol.L-1 lidamycin alone decreased Bcl-2 protein level, while lidamycin in combination with cisplatin strongly inhibited expression of Bcl-2 proteins in BEL-7402 cells.

CONCLUSIONThe results suggest that lidamycin enhancement of cisplatin-induced apoptosis associates with decrease of Bcl-2 protein expression, which may be useful for cancer chemotherapy.

Aminoglycosides ; pharmacology ; Antibiotics, Antineoplastic ; pharmacology ; Antineoplastic Agents ; pharmacology ; Apoptosis ; Carcinoma, Hepatocellular ; pathology ; Cisplatin ; pharmacology ; Drug Synergism ; Enediynes ; Humans ; Liver Neoplasms ; metabolism ; pathology ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; S Phase ; drug effects ; Tumor Cells, Cultured

AIMA bioassay method was established for the determination of active concentrations of lidamycin and studied its pharmacokinetics in mice and dogs.

METHODSCytotoxicity of lidamycin in vitro was used to determine drug serum concentrations in vivo.

RESULTSValidity of methodology met the requirements of pharmacokinetic study. The concentration-time profile in mice after iv lidamycin of 100, 50 and 10 microg x kg(-1) was best fitted with 2-compartmental model with T1/2alpha and T1/2beta of 0.77-1.8 min and 5.6-7.2 min, respectively. The AUC were 2851.3, 887.8 and 166.4 microg x min x L(-1), respectively and increased with dose nonlinearly. There were similar trends between AUC and the potency of tumor growth inhibition. After iv lidamycin of 12 microg x kg(-1) in dogs, the concentrations of lidamycin decreased rapidly and the AUC was 16 microg x min x L(-1), which were lower and quicker than those in mice. The levels in serum after second administration at day 15, were lower than those of the first.

CONCLUSIONActive concentrations and pharmacokinetics of lidamycin were obtained by bioassay method successfully. There are species differences and single and multi-dosing differences in the pharmacokinetics of lidamycin.

Aminoglycosides ; blood ; pharmacokinetics ; pharmacology ; Animals ; Antibiotics, Antineoplastic ; blood ; pharmacokinetics ; pharmacology ; Area Under Curve ; Biological Assay ; Dogs ; Enediynes ; Female ; Humans ; Injections, Intravenous ; KB Cells ; metabolism ; Liver Neoplasms ; pathology ; Male ; Mice ; Neoplasm Transplantation ; Sarcoma 180 ; pathology ; Species Specificity

AIMTo investigate the chemosensitivity to lidamycin (C-1027) in mdr1 gene overexpressing cancer cell lines established by drug induction and by gene-transfection.

METHODSDNA was cloned by RT-PCR and then eukaryotic expressing recombinant plasmid pcDNA3. 1/mdrl was constructed. Using Lipofectamine 2000, a strain of stably transfected human hepatoma cancer cells, HepG2/mdrl, was obtained. The mdr1 mRNA level, P-glycoprotein (P-gp) level and the activity of P-gp to extrude drugs in cancer cells were determined by RT-PCR, immunofluorescence analysis and rhodamine 123 efflux assay. The chemosensitivity of cancer cells with low or high mdr1 expression to lidamycin and other antitumor drugs was tested by MTT assay.

RESULTSThe mdr1 mRNA and P-gp levels in KBv200, MCF-7/ADR, and stably transfected HepG2/mdr1 cells were much higher than that in respective parent KB, MCF-7 and HepG2 cells. The IC50 values of lidamycin for KBv200, MCF-7/ADR and HepG2/mdrl cells were (0.24 +/- 0.20) nmol x L(-1), (0.028 +/- 0.011) nmol x L(-1), and (0.020 +/- 0.011) nmol x L(-1), respectively. Compared with parental cells, the values of resistant fold for KBv200, MCF-7/ADR and HepG2/mdr1 cells to lidamycin were 6.8, 1.6 and 1.3 fold; to adriamycin were 37.2, 181.3 and 8.8 fold; to taxol were 336.8, 49.2 and 40.3 fold, respectively.

CONCLUSIONLidamycin is highly active to multidrug resistant cancer cells. The chemosensitivity of those resistant cancer cells to lidamycin is approximately at the similar level as that of parent cancer cells.

ATP-Binding Cassette, Sub-Family B, Member 1 ; analysis ; genetics ; Aminoglycosides ; pharmacology ; Antibiotics, Antineoplastic ; pharmacology ; Cell Line, Tumor ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Enediynes ; pharmacology ; Genes, MDR ; Humans ; Neoplasms ; drug therapy ; pathology ; Transfection

This study is to investigate the inhibitory effect of lidamycin (LDM) and its combination with methotrexate (MTX) on lung metastasis of fibrosarcoma by bioluminescence imaging in athymic mice. A stable luciferase transfected HT-1080 cell line was constructed and the capability to establish experimental lung metastasis in athymic mice was confirmed. The optical imaging system was applied to evaluate the formation of lung metastasis in vivo. In addition, metastatic nodules were counted for the evaluation of inhibition rates. As shown, the fluorescent intensity of luciferase-transfected HT-1080 cells was colinear with the cell population and the minimal detected cell population was 100 cells/well. Optical imaging showed that the fluorescent intensity of treated group was apparently lower than that of the control. The inhibition rates of lung metastasis by LDM alone at 0.025 mg x kg(-1) and 0.05 mg x kg(-1) were 53.9% and 75.9%, respectively, while that of MTX alone at 0.5 mg x kg(-1) was 70.2%. The combination of LDM at 0.025 mg x kg(-1) and MTX at 0.5 mg x kg(-1) showed an inhibition rate of 88.7%. The coefficient of drug interaction (CDI) was 0.82. The results herein demonstrated that LDM alone had strong anti-metastasis effect on human fibrosarcoma HT-1080 and the inhibition efficacy is strengthened when combined with MTX.
Aminoglycosides ; administration & dosage ; Animals ; Antibiotics, Antineoplastic ; administration & dosage ; Antimetabolites, Antineoplastic ; administration & dosage ; Antineoplastic Combined Chemotherapy Protocols ; therapeutic use ; Cell Line, Tumor ; Drug Synergism ; Enediynes ; administration & dosage ; Female ; Fibrosarcoma ; pathology ; Humans ; Luminescent Measurements ; Lung ; pathology ; Lung Neoplasms ; drug therapy ; pathology ; secondary ; Methotrexate ; administration & dosage ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Random Allocation ; Transfection ; Xenograft Model Antitumor Assays

To investigate the antitumor activities of the immunoconjugates composed of anti-type IV collagenase monoclonal antibody Fab' fragment and lidamycin (LDM) prepared with different linkers. The immunoconjugates were prepared by linking Fab' to lysine-69 of LDM apoprotein by SPDP, LCSPDP, SMBS or SSMPB as the intermediate drug linkers. Immunoreactivities of the conjugates were determined by ELISA. The cytotoxicities of the conjugates were examined by clonogenic assay. In vivo antitumor effects of the conjugates were evaluated in nude mice bearing subcutaneously implanted HT-1080 tumor. ELISA assay showed that the conjugates retained part of the immunoreactivity of 3G11 against the antigen. The cytotoxicities of the Fab'-SMBS-LDM and Fab'-SSMPB-LDM to HT-1080 cells were significantly potent, compared with Fab'-SPDP-LDM, Fab'-LCSPDP-LDM and free LDM. In animal models at the same condition, free LDM, Fab'-SPDP-LDM and Fab'-LCSPDP-LDM inhibited the growth of HT-1080 tumor by 70.9%, 74.8% and 72.3%, while Fab'-SMBS-LDM and Fab'-SSMPB-LDM reached 78.0% and 87.7%, respectively. The median survival time of the mice treated with free LDM, Fab'-SPDP-LDM and Fab'-LCSPDP-LDM were prolonged by 71.9%, 82.2% and 107.5%, respectively, compared with that of untreated group. Whereas, the median survival time of Fab'-SMBS-LDM and Fab'-SSMPB-LDM were prolonged by 145.2% and 165.8%, respectively, indicating that Fab'-SSMPB-LDM was more effective than Fab'-SMBS-LDM in tumor suppression and life span prolongation. Fab'-SSMPB-LDM has more marked selective antitumor efficacy and lower toxicity, and might be a novel candidate for cancer therapy.
Aminoglycosides ; pharmacology ; Animals ; Antibiotics, Antineoplastic ; pharmacology ; Antibodies, Monoclonal ; immunology ; Cell Line, Tumor ; drug effects ; Cell Proliferation ; drug effects ; Collagenases ; immunology ; Enediynes ; pharmacology ; Fibrosarcoma ; pathology ; Humans ; Immunoconjugates ; pharmacology ; Immunoglobulin Fab Fragments ; immunology ; Matrix Metalloproteinase Inhibitors ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Neoplasm Transplantation ; Tumor Burden ; drug effects

This study is to investigate the tumor invasion and metastasis inhibition effects of the immunoconjugate composed of lidamycin and anti-type IV collagenase monoclonal antibody Fab' fragment. Boyden chamber assay was used to evaluate the influence of Fab'-LDM on HT-1080 cells invasion ability, gelatinase spectrum was used to measure the change of invasion factor MMP-2 and MMP-9's secretion, and RT-PCR was adopted to determine TIMP-1 mRNA expression level. The immunoconjugate inhibition of tumor in situ metastasis was also tested in nude mice. The Fab'-LDM conjugates had dose-dependent inhibition effect on HT-1080 cells' invasion. At the concentrations of 5 and 10 nmol L(-1), the Fab'-LDM inhibited the invasion by (60 +/- 12) % and (79 +/- 11) % respectively. At the concentration of 5 and 10 nmol L(-1), the Fab'-LDM inhibited the secretion of MMP-2 by (42 +/- 8) % and (54 +/- 6) % and that of MMP-9 by (57 +/- 3) % and (87 +/- 1) %, respectively. RT-PCR indicated that conjugates increased the anti-invasion factor TIMP-1 level. The in vivo experiment showed that, compared with the control group, the tumor inhibition rate in Fab', Fab'-LDM, and LDM group equaled to (30 +/- 13) %, (86 +/- 26) %, (74 +/- 22) % respectively. In conclusion, Fab'-LDM could inhibit the invasion and metastasis of tumor and it might be a new tumor biotherapy agent.
Aminoglycosides ; pharmacology ; Animals ; Antibiotics, Antineoplastic ; pharmacology ; Antibodies, Monoclonal ; immunology ; Cell Line, Tumor ; Enediynes ; pharmacology ; Fibrosarcoma ; metabolism ; pathology ; Humans ; Immunoconjugates ; pharmacology ; Immunoglobulin Fab Fragments ; pharmacology ; Matrix Metalloproteinase 2 ; immunology ; secretion ; Matrix Metalloproteinase 9 ; immunology ; secretion ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Neoplasm Invasiveness ; Neoplasm Metastasis ; Neoplasm Transplantation ; RNA, Messenger ; metabolism ; Tissue Inhibitor of Metalloproteinase-1 ; genetics ; metabolism ; Tumor Burden ; drug effects