Optimization of the assembly efficiency for lidamycin chromophore bound to its apoprotein: a case study using orthogonal array.

OBJECTIVE: Lidamycin (LDM) can be dissociated to an apoprotein (LDP) and an active enediyne chromophore (AE). The detached AE can reassemble with its LDP-containing fusion protein to endow the latter with potent antitumor activity. However, the reassembly of AE with LDP is affected by several factors. Our aim was to optimize the assembly efficiency of the AE with a LDP-containing fusion protein and investigate the influence of several factors on the assembly efficacy. METHODS: A method based on RP-HPLC was developed to analyze the assembly rate, and an orthogonal experimental design L(9) (3(4)) was used to investigate the effects of temperature, assembly time, pH and molecular ratio of LDP-containing fusion protein to AE on the assembly rate. Furthermore, the determined optimum conditions for the assembly rate of the LDP-containing fusion protein with AE were applied and evaluated. RESULTS: A calibration curve based on the LDM micromolar concentration against the peak-area of AE by HPLC was obtained. The order in which individual factors in the orthogonal experiment affected the assembly rate were temperature>time>pH>molar ratio of AE to protein and all were statistically significant (P<0.01). The optimal assembly conditions were temperature at 10°C, time of 12 h, pH 7.0, and the molar ratio of AE: protein of 5:1. The assembly rate of AE with a LDP-containing fusion protein was improved by 23% after condition optimization. CONCLUSION: The assembly rate of chromophore of lidamycin with its LDP-containing fusion protein was improved after condition optimization by orthogonal design, and the optimal conditions described herein should prove useful for the development of this type of LDP-containing fusion protein.

[Bioluminescence imaging evaluation of the inhibitory effect of lidamycin on lung metastasis of human fibrosarcoma in athymic mice].

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.

[In vivo imaging analysis of biodistribution of FITC-labeled Rituximab in lymphoma-bearing nude mice].

OBJECTIVE: To conduct an in vivo optical imaging analysis of the biodistribution of antibody Rituximab in lymphoma tumor-bearing nude mice. METHODS: Laser scanning confocal microscope and flow cytometry were employed to determine the affinity of FITC-labeled Rituximab (FITC-Rituximab) with human lymphoma Raji cells. And the in vivo optical imaging system was used to analyze the biodistribution of FITC-Rituximab in lymphoma-transplanted xenograft nude mice. RESULTS: The results of flow cytometry and laser scanning confocal microscope demonstrated that FITC-Rituximab had remarkable affinity with lymphoma Raji cells and was mainly bound at cell membrane. The results of in vivo imaging analysis suggested that FITC-Rituximab could specifically accumulated at peritumor tissue less than 1 h, then penetrated into the interior of tumor and concentrated in 3-4 h. And the specific concentration of FITC-Rituximab could still been observed more than 8-10 h whereas there was no apparent fluorescence at other tissues. Furthermore, the results observed from a two-flank tumor xenograft model showed that FITC-Rituximab possessed specific binding affinity for CD20-overexpressed lymphoma. CONCLUSION: The in vivo optical imaging system can accurately monitor the distribution of FITC-Rituximab in tumor-bearing nude mice. And this technique has a reference value and significance for a real-time analysis of tumor-targeting capability of antibody drugs.

Isolation and functional identification of a novel human hepatic growth factor: hepatopoietin Cn.

UNLABELLED: Hepatic stimulating substance (HSS) was first isolated from weanling rat liver in 1975 and found to stimulate hepatic DNA synthesis both in vitro and in vivo. Since then, mammalian and human HSS have been investigated for their potential to treat hepatic diseases. However, the essential nature in composition and structure of HSS remain puzzling because HSS has not been completely purified. Heating, ethanol precipitation, and ion-exchange chromatographies had been carried out to isolate the protein with specific stimulating activity from newborn calf liver, and [(3)H]thymidine deoxyribose (TdR)/bromodeoxyuridine (BrdU) incorporation and carboxyfluorescein diacetate succinimidyl ester (CFSE)-based proliferation assay to determine the bioactivity in vitro and in vivo. We report the purification of a novel 30-kDa protein from a crude extract of calf liver HSS. This protein is a member of the leucine-rich acidic nuclear protein family (LANP) and has been named hepatopoietin Cn (HPPCn). Studies of partially hepatectomized (PH) mice show that levels of HPPCn messenger RNA (mRNA) increase after liver injury. Furthermore, the recombinant human protein (rhHPPCn) was shown to stimulate hepatic DNA synthesis and activate signaling pathways involved in hepatocyte proliferation in vitro and in vivo. CONCLUSION: HPPCn is a novel hepatic growth factor that plays a role in liver regeneration.

Correction: Long non-coding RNA HoxA-AS3 interacts with EZH2 to regulate lineage commitment of mesenchymal stem cells.

[This corrects the article DOI: 10.18632/oncotarget.11538.].

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.

Jarid2 is essential for the maintenance of tumor initiating cells in bladder cancer.

Bladder cancer is the most common urologic malignancy in China, with an increase of the incidence and mortality rates over past decades. Recent studies suggest that bladder tumors are maintained by a rare fraction of cells with stem cell proprieties. Targeting these bladder tumor initiating cell (TICs) population can overcome the drug-resistance of bladder cancer. However, the molecular and genetic mechanisms regulating TICs in bladder cancer remain poorly defined. Jarid2 is implicated in signaling pathways regulating cancer cell epithelial-mesenchymal transition, and stem cell maintenance. The goal of our study was to examine whether Jarid2 plays a role in the regulation of TICs in bladder cancer. We found that knockdown of Jarid2 was able to inhibit the invasive ability and sphere-forming capacity in bladder cancer cells. Moreover, knockdown of Jarid2 reduced the proportion of TICs and impaired the tumorigenicity of bladder cancer TICs in vivo. Conversely, ectopic overexpression of Jarid2 promoted the invasive ability and sphere-forming capacity in bladder cancer cells. Mechanistically, reduced Jarid2 expression led to the upregulation of p16 and H3K27me3 level at p16 promoter region. Collectively, we provided evidence that Jarid2 via modulation of p16 is a putative novel therapeutic target for treating malignant bladder cancer.

Long non-coding RNA HoxA-AS3 interacts with EZH2 to regulate lineage commitment of mesenchymal stem cells.

Long non-coding RNAs (lncRNAs) play an important role in gene regulation and are involving in diverse cellular processes. However, their roles in reprogramming of gene expression profiles during lineage commitment and maturation of mesenchymal stem cells (MSCs) remain poorly understood. In the current study, we characterize the expression of a lncRNA, HoxA-AS3, during the differentiation of MSCs. We showed that HoxA-AS3 is increased upon adipogenic induction of MSCs, while HoxA-AS3 remains unaltered during osteogenic induction. Silencing of HoxA-AS3 in MSCs resulted in decreased adipogenesis and expression of adipogenic markers, PPARG, CEBPA, FABP4 and ADIPOQ. Conversely, knockdown of HoxA-AS3 expression in MSCs exhibited an enhanced osteogenesis and osteogenic markers expression, including RUNX2, SP7, COL1A1, IBSP, BGLAP and SPP1. Mechanistically, HoxA-AS3 interacts with Enhancer Of Zeste 2 (EZH2) and is required for H3 lysine-27 trimethylation (H3K27me3) of key osteogenic transcription factor Runx2. Our data reveal that HoxA-AS3 acts as an epigenetic switch that determines the lineage specification of MSC.

Small antibody fusion proteins with complementarity-determining regions and lidamycin for tumor targeting therapy.

Gelatinases are overexpressed in several types of maligancies and tumor stromal cells. Lidamycin is an enediyne antitumor antibiotic, which is composed of an apoprotein (LDP) and an active chromophore (AE). It is known that the heavy-chain complementarity-determining region-3 (CDR3) domain of scFv is important in antibody affinity. The aim of this study was to prepare the enediyne-energized fusion proteins with a heavy-chain CDR3 domain of anti-gelatinases scFv and lidamycin, and to evaluate their antitumor efficiency. Fusion proteins comprising the CDR3 domain and the lidamycin apoprotein were generated, and ELISA, immunofluorescence and FACS were used to analyze the binding of the fusion protein with antigen gelatinases. The purified fusion proteins were assembled with the lidamycin chromophore, and the antitumor effects were evaluated in vitro and in vivo. It was found that the CDR3-LDP and CDR3-LDP-CDR3 fusion proteins demonstrated high affinity towards antigen gelatinases. Following stimulation of CDR3-LDP with enediyne, the results of MTT showed potent cytotoxicity towards tumor cells; the IC50 values of CDR3-LDP-AE to HepG2 and Bel-7402 tumor cells were 1.05×10-11 and 6.6×10-14 M, respectively. In addition, CDR3-LDP-AE displayed a potent antitumor effect in H22 cell xenografts in mice; the combination of CDR3-LDP (10 mg/kg) and CDR3-LDP-AE (0.25 and 0.5 mg/kg) revealed that the tumor inhibitory rates were 85.2 and 92.7%, respectively (P<0.05 compared with CDR3-LDP-AE). In conclusion, these results suggest that the CDR3-LDP fusion protein and its analog CDR3-LDP-AE may both be promising candidates for tumor targeting therapy.

Lapatinib, a dual inhibitor of EGFR and HER2, has synergistic effects with 5-fluorouracil on esophageal carcinoma.

Epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) amplification occurs in over 30% of esophageal carcinomas. Combination therapies with EGFR and HER2-targeting agents and cytotoxic agents are considered a potential therapeutic option for esophageal cancer. We evaluated the antitumor effects of lapatinib, a dual tyrosine kinase inhibitor which simultaneously inhibits EGFR and HER2, 5-fluorouracil (5-Fu) alone and in combination on esophageal cancer cells. The antiproliferative activity of lapatinib, 5-Fu and lapatinib plus 5-Fu was measured by MTT assay and the combination index (CI) values were calculated. Additionally, cell cycle distribution of lapatinib alone and the combination with 5-Fu were detected by flow cytometry analysis. Annexin V-FITC and propidium iodide stain were used for analyzing the apoptotic cells after cells were treated with either agent alone or in combination. The EGFR and HER2 activated signaling pathways were monitored by western blotting. The combination of lapatinib and 5-Fu synergistically inhibited cell proliferation and exhibited an enhanced proapoptotic effect on esophageal cancer cells. The potentiation effect of combined treatment was associated with downregulation of EGFR and HER2 signaling pathways because data from western blot analysis showed that lapatinib in combination with 5-Fu markedly reduced the phosphorylation of EGFR and HER2, and inhibited the activation of downstream signaling molecules, such as AKT and ERK. A significant G1 arrest was also observed in cell cycle analysis after exposing cells to lapatinib, however, combination with 5-Fu did not enhance G1 arrest. These results indicate that the combination of the lapatinib and 5-Fu is a promising treatment option for esophageal carcinoma with HER2 amplification.

Antitumor activities of dFv-LDP-AE: An enediyne-energized fusion protein targeting tumor-associated antigen gelatinases.

Gelatinases play an important role in tumor growth and metastasis, and overexpression of these molecules is strongly correlated with poor prognosis in a variety of malignant tumors. Lidamycin is an enediyne antitumor antibiotic with potent cytotoxicity. We previously reported that a tandem scFv format (dFv-LDP-AE) showed enhanced binding ability with gelatinases compared with the scFv-lidamycin conjugate (Fv-LDP-AE). In this study, the antitumor activities of dFv-LDP-AE on hepatocellular carcinoma (HCC) were evaluated in vitro and in vivo. By SDS-PAGE analysis, it was found that partial fusion protein dFv-LDP existed as dimer; the results of ELISA and immunofluorescence demonstrated that the fusion protein dFv-LDP could efficiently bind to hepatoma cells in vitro. The apparent arrest of cell cycle at G2/M phase and induction of apoptosis at nanomole levels indicated that the dFv-LDP-AE was very potent against HCC. In in vivo experiments, dFv-LDP-AE shown enhanced cytotoxic effects compared to those of LDM. Administration at mouse tolerable dosage level, the inhibition rate of tumor growth was 89.5% of dFv-LDP-AE vs. 73.6% of LDM on transplantable H22 in mice (P<0.05) and, 87.3% of dFv-LDP-AE vs. 63.4% of LDM on hepatoma Bel-7402 in athymic mice (P<0.01). Small animal optical imaging showed that the FITC-labeled dFv-LDP preferentially localized in the tumor site in less than 30 min, which demonstrated remarkable tumor-targeting properties. Taken together with the above findings, the enediyne-energized fusion protein dFv-LDP-AE showed potential application as a new agent for therapeutic appications in HCC.

[Construction of energized fusion protein consisting of epidermal growth factor receptor oligopeptide ligand and lidamycin and its antitumor activity].

BACKGROUND AND OBJECTIVE: Epidermal growth factor receptor (EGFR) is abnormally overexpressed on many kinds of tumor cells. Lidamycin is an enediyne antibiotic with highly potent antitumor activity. This study was to construct a novel fusion protein by recombining EGFR specific oligopeptide ligand and lidamycin, and investigate its antitumor efficacy. METHODS: The fusion protein (Ec-LDP) was expressed in E.coli and purified by affinity chromatography. The purity of Ec-LDP was analyzed by high performance liquid chromatography (HPLC). ELISA, flow cytometry (FCM) and immunofluorescence assay were used to analyze the binding activity of Ec-LDP to different cancer cell lines. The energized fusion protein Ec-LDP-AE was prepared by integrating the active enediyne chromophore (AE) of lidamycin into the Ec-LDP protein. The cytotoxicity of Ec-LDP-AE was measured by MTT assay. RESULTS: Ec-LDP fusion protein was successfully constructed and secretorily expressed in E.coli, and the production of Ec-LDP protein was 18 mg per liter fermentation broth. The purity of Ec-LDP protein was 95.3%. Ec-LDP protein had strong binding activity to cancer cell lines highly expressing EGFR, such as MCF-7 and A431 cells. However, Ec-LDP had no binding activity to EGFR negative NIH 3T3 cells. The energized fusion protein Ec-LDP-AE showed potent cytotoxicity to MCF-7 and A431 cells with the half maximal inhibitory concentration (IC50) values of 3.06 x 10(-11) mol/L and 9.38 x 10(-13) mol/L, respectively. CONCLUSION: The energized fusion protein Ec-LDP-AE binds to EGFR specifically and kills cancer cells efficiently.