Tuftsin-tailored fusion protein inhibits the growth of circulating gastric tumor cells associated with macrophage phagocytosis.

Circulating tumor cells (CTCs) are a major cause of tumor metastasis and resistance to anticancer therapies. To date, no effective low-toxicity chemotherapeutic agents or antibodies have exhibited significant clinical activity against CTCs. Macrophages are important mediators of antitumor immunity. Tuftsin (TF), a tetrapeptide located at residues 289-292 of the CH2 domain of the Fc region of the IgG heavy chain, binds to Nrp-1, a receptor on the surface of macrophages that promotes phagocytosis and induces nonspecific activation of the immune system against tumors. Lidamycin (LDM) is an antitumor chemotherapy agent that is strongly cytotoxic to tumors and can dissociate into an apoprotein (LDP) and active enediyne (AE) in vitro. We previously constructed the fusion protein LDP-TF through genetic engineering and inserted the chromophore AE to produce LDM-TF, which can target macrophages to promote their phagocytic and cytotoxic activity against tumor cells. Preliminary experiments confirmed the anti-tumor activity of LDM-TFs. In this study, we found that LDM-TF effectively inhibited the growth of CTCs of gastric cancer origin and enhanced macrophage phagocytosis both in vivo and in vitro. Tumor cell expression of CD47, which helps to evade phagocytosis by macrophages, was substantially downregulated by LDM-TF. Notably, our in vitro experiments demonstrated that the combination of LDM-TF and anti-CD47 antibodies promoted phagocytosis more than either component alone. Our findings demonstrate the significant inhibitory effect of LDM-TF on the growth of CTCs of gastric cancer origin and suggest that the combination of LDM-TF and anti-CD47 antibodies may exhibit synergistic effects, thereby providing a new option for the clinical treatment of patients with advanced tumors that have metastasized.

Preparation and anti-tumor activity of a novel antibody-drug conjugate 607-LDM / 药学学报

Antibody-drug conjugates (ADCs) are one of the most important classes of anticancer therapeutics. Human epidermal growth factor receptor-2 (HER2), which is highly expressed in many types of aggressive cancers including breast and ovarian cancer, has been approved as an ideal target for ADCs. Lidamycin (LDM), developed by Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, is an enediyne-containing antibiotic with potent anti-tumor activity. LDM is a promising payload for ADCs. In the present research, using a special site-directed conjugating technology, we made a novel ADC (607-LDM) with a drug-to-antibody ratio (DAR) of 2 and composed of the anti-HER2 antibody 607 and LDM. The new ADC exhibited potent antitumor activity against human ovarian cancer SKOV3 and breast cancer BT-474 cells. It also induced apoptosis and G2/M arrest. In nude mice with SKOV3 xenografts and a tumor volume of 150-200 mm3, a single intravenous injection 607-LDM at 1 mg·kg-1 induced tumor growth inhibition of 72.4%, which was significant compared to either LDM (50.6%) or antibody (30.2%) treatment alone, or both in combination (50.1%, P < 0.05). All animal experiments were performed in accord with National Regulations and approved by the Animal Experiments Ethical Committee of College of Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences. The novel ADC designed in this study, 607-LDM, is a promising candidate for the treatment of HER2-positive cancers.

An albumin­binding domain and targeting peptide­based recombinant protein and its enediyne­integrated analogue exhibit directional delivery and potent inhibitory activity on pancreatic cancer with K­ras mutation.

Efficient enrichment and transmembrane transport of cytotoxic reagents are considered to be effective strategies to increase the efficiency and selectivity of antitumor drugs targeting solid tumors. In the present study, a recombinant protein ABD­LDP­Ec consisting of the albumin­binding domain (ABD), the apoprotein (LDP) of lidamycin (LDM) and an EGFR­targeting oligopeptide (Ec) was prepared by DNA recombination and bacterial fermentation, and was integrated with the enediyne chromophore (AE) of lidamycin to generate its enediyne­integrated analogue ABD­LDP­Ec­AE. ABD­LDP­Ec exhibited high binding capacity to both albumin and EGFR­positive pancreatic cancer cells, and was internalized into the cytoplasm through receptor­mediated endocytosis and albumin­driven macropinocytosis of K­ras mutant cells. In animal experiments, ABD­LDP­Ec demonstrated notable selective distribution in pancreatic carcinoma xenografts by passive targeting of albumin captured in the blood and was retained in the tumor for 48 h. ABD­LDP­Ec and ABD­LDP­Ec­AE exhibited inhibitory activity in cell proliferation and AsPC­1 xenograft growth, and ABD­LDP­Ec­AE increased the tumor growth inhibition rate by 20% compared with natural LDM. The results indicated that the introduction of ABD­based multi­functional drug delivery may be an effective approach to improve the efficacy of antitumor drugs, especially for K­ras mutant cancers.

Distribution, excretion and pharmacokinetic research of dual target ligand-based lidamycin in rats / 中国药理学与毒理学杂志

OBJECTIVE: To study the distribution, excretion and other pharmacokinetic characteristics of dual target ligand-based lidamycin (DTLL) in rats. METHODS: [125l] radioactivity isotope tracing method was used to determine the pharmacokinetic parameters of DTLL which was injected intravenously via the tail vein of healthy Wistar rats at a single dose of [125l] DTLL 2625 kBq · 0.05 mg-1· kg-1. The samples from rat plasma, tissue, feces, urine and bile were obtained to analyze the distributions of DTLL in rats after administration and to calculate the cumulative excretion scores by using a liquid scintillation counting analyzer with the WinNolin program. RESULTS: The area under the concentration-time curve (AUC0-∞) of DTLL was (184±33) h·μg·L-1, with half time (t1/2) and cleanrance (Cl) at (3.98±0.75) h and (278±41) mL·h-1· kg-1, respectively. DTLL was mainly distributed in whole body tissues without any accumulation observed. The excretion rate of DTLL was (82.5±2.6)% for urine, compared with (10.4±6.6)% in feces and (92.9±7.4)% in total. CONCLUSION: DTLL is distributed rapidly in the whole body without obvious accumulation. Most of the DTLL administered is excreted through feces and urine.

Effects of Lidamycin on cell cycle, apoptosis, autophagy and epithelial mesenchymal transformation of human cervical carcinoma Hela cells / 中国药理学通报

Aim To investigate the effects of lidamycin (LDM) on cell cycle, apoptosis, autophagy and epithelial mesenchymal transformation (EMT) of human cervical cancer Hela cells as well as its underlying mechanism. Methods MTT assay was used to analyze the effect of LDM on Hela cell growth. Flow cytometry was used to detect the effect of LDM on cell cycle, apoptosis and mitochondrial membrane potential. Western blot was used to detect the expression levels of proteins. Transwell assay was used to analyze the effect of LDM on migration and invasion of Hela cells. QT-PCR was employed to analyze the effects of LDM on LSD1 (lysine specific demethylase 1) expression level in Hela cells. Results LDM could significantly inhibit Hela cell proliferation in a time-and concentration-dependent manner, with the IC50 values of 19. 24 ng . mL-1 (24 h), 6.678 ng . mL- 1(48 h) and 3.221 ng . mL-1 (72 h). LDM could induce G2/M cycle arrest and mitochondrial-mediated endogenous apoptosis in Hela cells. Low concentration of LDM(5 ng . mL-1) could induce autophagy, but high concentration of LDM(20 ng . mL-1 ) could inhibit autophagy in Hela cells. In addition, LDM could inhibit the migration and invasion of Hela cells, change the expression levels of EMT-related factors, but LSD1 was not involved in this process. Conclusions LDM can effectively inhibit proliferation, invasion and metastasis of Hela cervical cancer cells, and its mechanism may be closely related to cell cycle arrest, apoptosis, interfering autophagy and inhibition of EMT.

EGFR-targeting, ß-defensin-tailored fusion protein exhibits high therapeutic efficacy against EGFR-expressed human carcinoma via mitochondria-mediated apoptosis.

Defensins play an essential role in innate immunity. In this study, a novel recombinant ß-defensin that targets the epidermal growth factor receptor (EGFR) was designed and prepared. The EGFR-targeting ß-defensin consists of an EGF-derived oligopeptide (Ec), a ß-defensin-1 peptide (hBD1) and a lidamycin-derived apoprotein (LDP), which serves as the "scaffold" for the fusion protein (Ec-LDP-hBD1). Ec-LDP-hBD1 effectively bound to EGFR highly expressed human epidermoid carcinoma A431 cells. The cytotoxicity of Ec-LDP-hBD1 to EGFR highly expressed A431 cells was more potent than that to EGFR low-expressed human lung carcinoma A549 and H460 cells (the IC50 values in A431, A549, and H460 cells were 1.8 ± 0.55, 11.9 ± 0.51, and 5.19 ± 1.21 µmol/L, respectively); in addition, the cytotoxicity of Ec-LDP-hBD1 was much stronger than that of Ec-LDP and hBD1. Moreover, Ec-LDP-hBD1 suppressed cancer cell proliferation and induced mitochondria-mediated apoptosis. Its in vivo anticancer action was evaluated in athymic mice with A431 and H460 xenografts. The mice were administered Ec-LDP-hBD1 (5, 10 mg/kg, i.v.) two times with a weekly interval. Administration of Ec-LDP-hBD1 markedly inhibited the tumor growth without significant body weight changes. The in vivo imaging further revealed that Ec-LDP-hBD1 had a tumor-specific distribution with a clear image of localization. The results demonstrate that the novel recombinant EGFR-targeting ß-defensin Ec-LDP-hBD1 displays both selectivity and enhanced cytotoxicity against relevant cancer cells by inducing mitochondria-mediated apoptosis and exhibits high therapeutic efficacy against the EGFR-expressed carcinoma xenograft. This novel format of ß-defensin, which induces mitochondrial-mediated apoptosis, may play an active role in EGFR-targeting cancer therapy.

An arginine-rich cell penetrating peptide contained anti-gelatinase scFv-LDM fusion protein shows potent antitumor efficacy in pancreatic cancer.

Pancreatic cancer (PC) is one of the most dangerous cancers with less than 5% survival rate in 5 years. This study was to evaluate the antitumor activities of dFv-LDP-AE and dFv-R-LDP-AE, two energized fusion protein targeting gelatinases, on pancreatic cancer. The fusion protein dFv-LDP-AE consists of two tandem anti-gelatianses scFv and an enediyne antibiotic lidamycin (LDM) for receptor binding and cell killing. To improve the penetration capability, the fusion protein dFv-LDP-AE was integrated with an arginine-rich cell penetrating peptide (Arg)9 and then generated the fusion protein dFv-R-LDP-AE. The current study demonstrated that dFv-LDP and dFv-R-LDP had high affinity with the antigen gelatinases and PC cells, the integration of (Arg)9 could increase the penetration rate of fusion protein in SW-1990 and PANC-1 cells. After enediyne-energized with chromophore of lidamycin, the energized fusion protein dFv-LDP-AE and dFv-R-LDP-AE showed potent cytotoxicity to PC cells and could induced the robust cell apoptosis and necrosis in vitro. Western blot showed that dFv-R-LDP-AE could increase PARP cleavage, and inhibited the expression of VEGF, Cyclin D1, Cox-2 and Bcl-2 in SW-1990 and PANC-1 cells. In vivo, at a tolerated dosage, dFv-LDP, dFv-LDP-AE and dFv-R-LDP-AE inhibited tumor growth by 20.42%, 56.31% (P < 0.01, compared to that of control) and 74.2% (P < 0.05, compared to that of dFv-LDP-AE) in pancreatic cancer SW-1990 xenografted mice, respectively. Moreover, the results of in vivo optical imaging showed that fusion protein dFv-R-LDP displayed prominent accumulation in the tumor in SW-1990 xenografted mice and Capan-2 orthotopic transplanted mice. These results showed that dFv-R-LDP-AE possessed potent antitumor efficacy on PC, which indicating it could be a promising candidate for targeting therapy of PC.

Bispecific antibody-drug conjugate targeting egfr and cd13 inhibited angiogenesis and tumor cell migration and invasion / 中国药学杂志

OBJECTIVE: To investigate the inhibitory effects of bispecific antibody-drug conjugate Fv-LDM-NGR targeting EGFR and CD13 on human tumor cells and endothelial cells,and possible mechanisms. METHODS: Human breast cancer cells MCF-7, human lung adenocarcinoma cells A549 and human microvascular endothelial cells HMEC-1, were studied. MTT assay was applied to measure proliferative activity of tumor cells. The influence of Fv-LDM-NGR on tube formation of HMEC-1 was observed. Transwell assay was applied to measure migration and invasion capacity in tumor cells. Western blot was applied for analyzing intracellular signaling transduction pathways. Flow cytometry, Hochest stain and Annexin -FITC/PI were used to detect cell cycle and apoptosis. RESULTS: Fv-LDM-NGR could inhibit the proliferation of tumor cells and microvascular endothelial cells with IC50 values of 10-14-10-12mol•L-1. Fv-LDM-NGR prevented tube formation in microvascular endothelial cells, and suppressed migration and invasion in tumor cells. Fv-LDM-NGR interfered with the intracellular signaling transduction pathways, then caused G2/M and S phase arrest and induced apoptosis. CONCLUSION :Bispecific antibody-drug conjugate Fv-LDM-NGR could prevent cell invasion in tumor cells and tube formation in microvascular endothelial cells through blocking activity of CD13. And it could down-regulate the expression and the phosphorylation of EGFR, interfere with cellular signal pathways, induce cell cycle arrest and cell apoptosis, and inhibit cell proliferation and migration.

A bispecific enediyne-energized fusion protein targeting both epidermal growth factor receptor and insulin-like growth factor 1 receptor showing enhanced antitumor efficacy against non-small cell lung cancer.

Epidermal growth factor receptor (EGFR) and insulin-like growth factor 1 receptor (IGF-1R) both overexpressed on non-small cell lung cancer (NSCLC) and are known cooperatively to promote tumor progression and drug resistance. This study was to construct a novel bispecific fusion protein EGF-IGF-LDP-AE consisting of EGFR and IGF-IR specific ligands (EGF and IGF-1) and lidamycin, an enediyne antibiotic with potent antitumor activity, and investigate its antitumor efficacy against NSCLC. Binding and internalization assays showed that EGF-IGF-LDP protein could bind to NSCLC cells with high affinity and then internalized into cells with higher efficiency than that of monospecific proteins. In vitro, the enediyne-energized analogue of bispecific fusion protein (EGF-IGF-LDP-AE) displayed extremely potent cytotoxicity to NSCLC cell lines with IC50<10-11 mol/L. Moreover, the bispecific protein EGF-IGF-LDP-AE was more cytotoxic than monospecific proteins (EGF-LDP-AE and LDP-IGF-AE) and lidamycin. In vivo, EGF-IGF-LDP-AE markedly inhibited the growth of A549 xenografts, and the efficacy was more potent than that of lidamycin and monospecific counterparts. EGF-IGF-LDP-AE caused significant cell cycle arrest and it also induced cell apoptosis in a dosage-dependent manner. Pretreatment with EGF-IGF-LDP-AE inhibited EGF-, IGF-stimulated EGFR and IGF-1R phosphorylation, and blocked two main downstream signaling molecules AKT and ERK activation. These data suggested that EGF-LDP-IGF-AE protein would be a promising targeted agent for NSCLC patients with EGFR and/or IGF-1R overexpression.

Lidamycin decreases CD133 expression in hepatocellular carcinoma via the Notch signaling pathway.

Cluster of differentiation (CD)133 is considered a molecular marker of cancer stem cells in hepatocellular carcinoma. In the present study, the effect of lidamycin (LDM) on CD133 expression in hepatocellular carcinoma (Huh7 cells) was evaluated and the potential molecular mechanism was investigated. Flow cytometry analysis, as well as sorting, sphere formation and western-blot assays, were performed in vitro to explore the effects of LDM on CD133 expression. A subcutaneous tumor model in nude mice was used to observe the effects of LDM on tumor volume and CD133 protein in vivo. To investigate the potential underlying molecular mechanism, Notch signaling pathway activity was detected by western blot analysis and reverse transcription-quantitative polymerase chain reaction. The proportion of CD133+ cells and the expression of CD133 protein were revealed to be downregulated by LDM. Sphere formation of sorted CD133+ cells was suppressed 7 days after LDM treatment. In addition, LDM inhibited tumor volume formed from sorted CD133+ cells and CD133 protein level in vivo. LDM decreased the mRNA level of NOTCH1, Hes1 (Hes family BHLH transcription factor 1) and Hey1 (Hes-related family BHLH transcription factor with YRPW motif 1) genes; consequently, the protein expression of NOTCH1, Notch intracellular domain, Hes1 and Hey1 was decreased by LDM. Downregulation of the Notch signaling pathway by LDM was enhanced through combination with N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester. In brief, these data suggest that LDM suppresses CD133 expression via the Notch signaling pathway, indicating the potential mechanism of LDM on CD133 and the benefits for further clinical application.

Complete genome sequence of Streptomyces globisporus C-1027, the producer of an enediyne antibiotic lidamycin.

Streptomyces globisporus C-1027 produces a nine-membered enediyne antitumor antibiotic lidamycin. Here we report the complete genome sequence of S. globisporus C-1027, which consists of a 7,608,611 bp linear chromosome, a 167,754 bp linear plasmid SGLP1 and a 7,234 bp circular plasmid pSGL1. The biosynthetic gene cluster for lidamycin was located in the linear plasmid SGLP1. Genome analysis also revealed a number of genes related to biosynthesis of diverse secondary metabolites. The genome sequence of C-1027 will enable us to disclose biosynthetic pathways of these secondary metabolites and discover new natural products with potential applications notably in human health.

Construction of an enediyne-energized fusion protein IGF-LDP-AE and its antitumor activity on non-small cell lung cancer / 中国药学杂志

OBJECTIVE: To construct a novel fusion protein contained insulin-like growth factor 1 (IGF-1) and lidamycin (LDM) and evaluate its antitumor activity on non-small cell lung cancer (NSCLC). METHODS: DNA fragment coding for fusion protein (ldp-igf) was synthesized by linking apoprotein of lidamycin (ldp) with igf-1, and then was cloned into the plasmid pET30a. Fusion protein LDP-IGF was expressed in E.coli as inclusion bodies and was purified by Ni2+ affinity chromatography. Binding affinity of LDP-IGF to NSCLC cells was evaluated by immunofluorescence assay and flow cytometry-based binding assay. MTT assay was used to measure the in vitrocytotoxicity of LDP-IGF and its enediyne-energized analogue LDP-IGF-AE. PI staining assay and Annexin V-FITC/PI staining assay were used to analyze the cell cycle arrest and cell apoptosis after treatment with LDP-IGF-AE, respectively. RESULTS: Active soluble LDP-IGF protein was prepared by isolation, purification, denaturation and refolding, and the production of LDP-IGF was 12 mg per liter fermentation broth. Both of immunofluorescence assay and flow cytometry-based binding assay showed that LDP-IGF has strong binding activity to NSCLC cells. Enediyne-energized fusion protein LDP-IGF-AE exhibited potent cytotoxicity to NSCLC cells in vitro, and it is more potent than that of LDM. Furthermore, fusion protein LDP-IGF without active enediyne was also cytotoxic to A549 cells at high concentrations (50 and 100 μg·mL-1). LDP-IGF-AE could cause significant G2-M arrest in A549 and H460 cells, and it also induced the apoptosis in NSCLC cells in a concentration-dependent manner. CONCLUSION: Fusion protein LDP-IGF-AE shows potent antitumor efficacy in vitro on NSCLC, suggesting it could be a promising candidate for targeted therapy.

Immunogenic apoptosis of human Caski cervical cancer cells induced by Lidamy-cin / 中国免疫学杂志

Objective:To investigate effects of Lidamycin (LDM,C-1027) on the proliferation and immunogenic transform of human Caski cervical cancer cells and to provide the basic experiment data and theoretical supports for establishment of the new immu-notherapy method mediated by LDM. Methods:MTT was used for the analysis of cell proliferation;apoptosis rate was analyzed by flow cytometry;Western blot was used to analyze the effect of LDM on the expression of Bax and Bcl-2 in Caski cells;the Flow cytometry was used to detect the expression of Calreticulin ( CRT ) on the cell surface. Results: Lidamycin inhibited proliferation of Caski cells significantly in the time-and dose-dependent manners;The apoptotic cell ratio induced by 5 μg/L Lidamycin was 11. 5% ,Comparing with the control group, Lidamycin treatment increased Bax but decreased Bcl-2 contents significantly within Caski cells, it also significantly increased the expression of CRT on the cell surface of Caski cells from 2. 31% to 67. 2%. Conclusion: Lidamycin has pharmacological activity in inhibiting proliferation of the human cervical Caski cells and the underlying mechanism is related with inducing the intrinsic mitochondrial pathway of apoptosis. In the same time,Lidamycin can increase the expression of CRT on the cell surface,so it may have the ability to promote the immunogenic apoptosis of tumor cells.

Site-specific PEGylation of lidamycin and its antitumor activity.

In this study, N-terminal site-specific mono-PEGylation of the recombinant lidamycin apoprotein (rLDP) of lidamycin (LDM) was prepared using a polyethyleneglycol (PEG) derivative (M w 20 kDa) through a reactive terminal aldehyde group under weak acidic conditions (pH 5.5). The biochemical properties of mPEG-rLDP-AE, an enediyne-integrated conjugate, were analyzed by SDS-PAGE, RP-HPLC, SEC-HPLC and MALDI-TOF. Meanwhile, in vitro and in vivo antitumor activity of mPEG-rLDP-AE was evaluated by MTT assays and in xenograft model. The results indicated that mPEG-rLDP-AE showed significant antitumor activity both in vitro and in vivo. After PEGylation, mPEG-rLDP still retained the binding capability to the enediyne AE and presented the physicochemical characteristics similar to that of native LDP. It is of interest that the PEGylation did not diminish the antitumor efficacy of LDM, implying the possibility that this derivative may function as a payload to deliver novel tumor-targeted drugs.

Transarterial oily chemoembolization with lidamycin shows potent therapeutic efficacy in VX2 rabbit liver tumor.

Transarterial oily chemoembolization (TOCE) is one of the most effective approaches for the treatment of patients with hepatocellular carcinoma (HCC), who are not suitable for surgical therapy. Lidamycin (LDM), a potent antitumor antibiotic, demonstrates good antitumor efficacy in various tumor types, both in vitro and in vivo. In this study, the antitumor efficacy of LDM combined with TOCE against the rabbit VX2 tumor was assessed. A toxicity assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) demonstrated that a combination of LDM with lipiodol did not impair the cytotoxicity of LDM against HepG2 cells in vitro. Using TOCE in rabbit VX2 tumor models, LDM showed a more powerful inhibitory effect against the tumor and lowered the expression levels of proliferating cell nuclear antigen (PCNA), cluster of differentiation 31 (CD31), and vascular endothelial growth factor (VEGF) compared to Adriamycin (ADM); moreover, this improvement was not accompanied by an increase of hepatotoxicity as shown by alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. These results suggested that LDM combined with TOCE may be a feasible strategy in HCC therapy in the future.

Lidamycin inhibits tumor initiating cells of hepatocellular carcinoma Huh7 through GSK3ß/ß-catenin pathway.

Recently, tumor initiating cells are considered as the central role of tumorigenicity in hepatocellular carcinoma. Enediyne anticancer antibiotic lidamycin with great potential antitumor activity is currently evaluated in Phase II clinical trials. In this study, we evaluated the effect of lidamycin on tumor initiating cells of hepatocellular carcinoma Huh7 and identified the potential mechanism. Flow cytometry analysis and sorting assay, surface marker assay, sphere formation assay, and aldefluor assay were used to evaluate the effect of lidamycin on Huh7 tumor initiating cells in vitro. To investigate the potential mechanism, the activity of GSK3ß/ß-catenin pathway was detected by Western blot and T cell factors transcriptional activity assay. Subcutaneous tumor model in nude mice was used to observe in vivo effect of lidamycin on Huh7 cells. Lidamycin decreased the proportion of EpCAM+ cells and the expression of EpCAM protein. Lidamycin inhibited sphere formation of sorted EpCAM+ cells in 7 d, and of parental cells in three serial passages. The population of aldehyde dehydrogenase-positive cells was reduced by lidamycin. In addition, lidamycin restrained tumor volume and incidence in vivo. Lidamycin activated GSK3ß, and degraded the activity of ß-catenin. Consequently, transcriptional activity of ß-catenin/T cell factors was decreased. In brief, these results suggest that lidamycin suppressed Huh7 tumor initiating cells via GSK3ß/ß-catenin pathway. These findings reveal the potential mechanism of lidamycin on tumor initiating cells and the benefit for further clinical evaluation.

Antitumor efficacy of lidamycin via hepatic arterial interventional or intravenous administration in rabbit VX2 liver cancer / 军事医学

Objective To investigate the difference of effect between interventional treatments and intravenous therapy of lidamycin on VX2 rabbit liver cancer.Methods VX2 Carcinoma cells were surgically implanted into the left liver lobe of 12 New Zealand white rabbits to establish the VX2 rabbit liver tumor model.Tumor size was detected by type-B ultrasonic diagnostic instrument.The rabbits were randomly divided into two groups of six,respectively treated with the hepatic inter-ventional administration of lidamycin (LDM)(1 ml,0.05 mg/kg)under the guidance of digital subtraction angiography (DSA)(group A)and with the auricular intravenous administration of LDMat the same dose (group B).All the rabbits were sacrificed and anatomized on day 10 after treatment,whose liver tumor was fixed with 4% paraformaldehyde solution and embedded in paraffin.Proliferating cell nuclear antigen (PCNA)and CD34 expression in the sample sections of tumor tissue were assessed through immunohistochemical staining.The levels of alanine transaminase (ALT)and aspartate trans-aminase(AST)were detected by Cobas 8000.Finally,the inhibition of VX2 tumor was evaluated.Results The VX2 tumor volumes were all increased at 10 day after LDMtreatment.However,the tumors in group A were smaller than those of group B (P <0.05).The results of immunohistochemistry showed that the intervention therapy of LDM could further lower the expression of CD34 and PCNA compared to group B.Conclusion Hepatic interventional administration of LDM under the guidance of DSA produces a better effect on attenuating the tumor growth than the intravenous administration of LDM.

Lidamycin regulates p53 expression by repressing Oct4 transcription.

Antitumor antibiotic lidamycin (LDM) is widely used in the treatment of a variety of cancers. Here we demonstrated that LDM up-regulates the expression of the tumor suppressor p53 gene by repressing Oct4 transcription. We showed that low dose LDM-induced increase of p53 expression and decrease of Oct4 expression in P19 and HCT116-p53(+/+) cells. Knockdown of Oct4 expression by siRNA led to activation of p53 in both cell lines, whereas ectopical expression of Oct4 significantly inhibited p53 expression in P19 cells. LDM-induced p53 activation was blocked by ectopical expression of Oct4.

Synergistic inhibition of angiogenesis and glioma cell-induced angiogenesis by the combination of temozolomide and enediyne antibiotic lidamycin.

Present work mainly evaluated the inhibitory effects of lidamycin (LDM), an enediyne antibiotic, on angiogenesis or glioma-induced angiogenesis in vitro and in vivo, especially its synergistic anti-angiogenesis with temozolomide (TMZ). LDM alone efficiently inhibited proliferations and induced apoptosis of rat brain microvessel endothelial cells (rBMEC). LDM also interrupted the tube formation of rat brain microvessel endothelial cells (rBMEC) and rat aortic ring spreading. The blockade of rBMEC invasion and C6 cell-induced rBMEC migration by LDM was associated with decrease of VEGF secretion in a co-culture system. TMZ dramatically potentiated the effects of LDM on anti-proliferation, apoptosis induction, and synergistically inhibited angiogenesis events. As determined by western blot and ELISA, the interaction of tumor cells and the rBMEC was markedly interrupted by LDM plus TMZ with synergistic regulations of VEGF induced angiogenesis signal pathway, tumor cell invasion/migration, and apoptosis signal pathway. Immunofluorohistochemistry of CD31 and VEGF showed that LDM plus TMZ resulted in synergistic decrease of microvessel density (MVD) and VEGF expression in human glioma U87 cell subcutaneous xenograft. This study indicates that the high efficacy of LDM and the synergistic effects of LDM plus TMZ against glioma are mediated, at least in part, by the potentiated anti-angiogenesis.

Tissue factor-targeted lidamycin inhibits growth and metastasis of colon carcinoma.

Colon cancer is the third most common cancer in the world. The overexpression of tissue factor (TF) in colon cancer cells makes it an ideal target for colon cancer therapy. The purpose of the present study was to develop a TF-targeting energized fusion protein, mlFVII-LDP-AE, which is composed of a mouse Factor VII light chain (mlFVII) as the targeting domain conjugated to the highly cytotoxic antibiotic lidamycin (LDM, LDP-AE) as the effector domain. The potential efficacy of mlFVII-LDP-AE for mouse colon cancer therapy was tested in a mouse colon cancer subcutaneous xenograft model and a live metastasis model in BALB/c mice. mlFVII-LDP-AE showed a tumor growth inhibition rate of 91.2% (at a dose of 0.8 mg/kg) and a tumor metastasis inhibition rate of 84.7% (at a dose of 0.6 mg/kg). The results showed that mlFVII-LDP-AE was able to effectively inhibit the growth and metastasis of mouse colon cancer. As human TF and FVII have features similar to those of mice, human FVII light chain (hlFVII)-targeted LDM (hlFVII-LDP-AE) may be expected to have therapeutic potential for human colon cancer.