[Research status of Bovis Calculus and relevant Chinese patent medicines based on bibliometric analysis].

With scarce resources, natural Bovis Calculus is expensive and hard to meet clinical demand. At the moment, four kinds of Bovis Calculus are available on the market: the natural product, in vitro cultured product, synthesized product, and the product formed in cow after manual intervention. In this study, papers on the four kinds of Bovis Calculus products and relevant Chinese patent medicines were searched from Web of Science, PubMed, and China National Knowledge Infrastructure(CNKI). CiteSpace, citexs AI, and CNKI were employed for bibliometric analysis and knowledge map analysis. On this basis, the status, trend, and focuses of research on Bovis Calculus and relevant Chinese patent medicines were summarized. The results suggested overall slow development in the research on Bovis Calculus and relevant Chinese patent medicines with three typical growth stages. It is consistent with the development of Bovis Calculus substitutes and the national policy for the development of traditional Chinese medicine. At the moment, the research on Bovis Calculus and relevant Chinese patent medicines has been on the rise. In recent years, there has been an explosion of research on them, particularly the quality control of Bovis Calculus and the Chinese patent medicines, the pharmacological efficacy of Chinese patent medicines, such as Angong Niuhuang Pills, and the comparison of the quality of various Bovis Calculus products. However, there is a paucity of research on the pharmacological efficacy and the mechanism of Bovis Calculus. This medicinal and the relevant Chinese patent medicines have been studied from diverse perspectives and China becomes outstanding in this research field. However, it is still necessary to reveal the chemical composition, pharmacological efficacy, and mechanism through multi-dimensional deep research.

[Research on network pharmacology of alkaloids in Sophora alopecuroides].

It was aimed at exploring the potential pharmacological effects of alkaloids in Sophora alopecuroides by means of network pharmacology in this study. The main alkaloids in S. alopecuroides were collected for analysis of drug properties, prediction of potential targets and screening of signaling pathways. DAVID analysis tool combined with KEGG database was used to annotate and analyze the signaling pathway. The alkaloids-targets-signaling pathways network was built through Cytoscape software. Results showed that 17 alkaloids in S. alopecuroides involved 49 targets (170 times in all) and 22 important signaling pathways. Three nodes in model of network pharmacology were cross-linked, and the metabolic pathways were coordinated and regulated by each other. It indicated that alkaloids in S. alopecuroides may have therapeutic effect on diseases of cancer, metabolic disorder, endocrine system, digestive system, nervous system and so on.

Construction of a genetically engineered chimeric apoprotein consisting of sequences derived from lidamycin and neocarzinostatin.

Neocarzinostatin (NCS) consists of an enediyne chromophore and an apoprotein (NCP). Lidamycin (LDM) is composed of another active enediyne chromophore (AE) and an acidic protein (LDP). Although the structures of NCP and LDP are very similar, LDM has been shown to have an increased tumor-suppressive activity than that of NCS. The aim of this study was to construct a chimeric protein (CMP) that consists of both the terminus residue of NCP and an LDP pocket-forming residue that can bind AE. This CMP will have a structure similar to NCS and an antitumor activity similar to LDM. The assembling efficiency of LDP, CMP, and NCP was 73.9, 1.5, and 1.1%, respectively. The cytotoxicity was consistent with their assembling efficiency of AE in proteins. When CMP-AE and NCP-AE were administered at equivalent AE doses of LDM, the inhibition rate of CMP-AE was the same as LDM and significantly higher than that of NCP-AE. Our study implied that the binding activity between LDP and AE was very specific. The terminus residue of LDP could affect the specifically binding activity. The pocket-forming residue could confer a protective function to the chromophore. Further investigation of its bioactivity might serve as a new drug design strategy and drug-delivery carrier in targeted cancer therapy.

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.

Genetically engineered endostatin-lidamycin fusion proteins effectively inhibit tumor growth and metastasis.

BACKGROUND: Endostatin (ES) inhibits endothelial cell proliferation, migration, invasion, and tube formation. It also shows antiangiogenesis and antitumor activities in several animal models. Endostatin specifically targets tumor vasculature to block tumor growth. Lidamycin (LDM), which consists of an active enediyne chromophore (AE) and a non-covalently bound apo-protein (LDP), is a member of chromoprotein family of antitumor antibiotics with extremely potent cytotoxicity to cancer cells. Therefore, we reasoned that endostatin-lidamycin (ES-LDM) fusion proteins upon energizing with enediyne chromophore may obtain the combined capability targeting tumor vasculature and tumor cell by respective ES and LDM moiety. METHODS: In this study, we designed and obtained two new endostatin-based fusion proteins, endostatin-LDP (ES-LDP) and LDP-endostatin (LDP-ES). In vitro, the antiangiogenic effect of fusion proteins was determined by the wound healing assay and tube formation assay and the cytotoxicity of their enediyne-energized analogs was evaluated by CCK-8 assay. Tissue microarray was used to analyze the binding affinity of LDP, ES or ES-LDP with specimens of human lung tissue and lung tumor. The in vivo efficacy of the fusion proteins was evaluated with human lung carcinoma PG-BE1 xenograft and the experimental metastasis model of 4T1-luc breast cancer. RESULTS: ES-LDP and LDP-ES disrupted the formation of endothelial tube structures and inhibited endothelial cell migration. Evidently, ES-LDP accumulated in the tumor and suppressed tumor growth and metastasis. ES-LDP and ES show higher binding capability than LDP to lung carcinoma; in addition, ES-LDP and ES share similar binding capability. Furthermore, the enediyne-energized fusion protein ES-LDP-AE demonstrated significant efficacy against lung carcinoma xenograft in athymic mice. CONCLUSIONS: The ES-based fusion protein therapy provides some fundamental information for further drug development. Targeting both tumor vasculature and tumor cells by endostatin-based fusion proteins and their enediyne-energized analogs probably provides a promising modality in cancer therapy.

Bortezomid enhances the efficacy of lidamycin against human multiple myeloma cells.

The proteasome inhibitor bortezomib has been applied successfully to treat multiple myeloma (MM). Its synergistic effects with other anticancer drugs have been studied widely. In the present study, it was found that lidamycin (LDM), a member of the enediyne antibiotic family, showed much more potent cytotoxicity than bortezomib to MM cell lines: U266 and SKO-007. Here, we investigated the potential synergy of bortezomib and LDM on MM cells. The results showed that cotreatment of bortezomib and LDM synergistically induced cytotoxicity and apoptosis in MM cell lines, followed by enhanced caspase-3 cleavage and degradation of poly-ADP-ribose polymerase together with the decreased nuclear factor-κB protein. These two drugs synergistically induced apoptosis, which was associated with enhanced activation of two mitogen-activated protein kinases: p38 mitogen-activated protein kinase and c-Jun NH(2)-terminal kinase. Moreover, bortezomib plus LDM synergistically induced apoptosis was also associated with downregulation of extracellular signal-regulated kinase, and induction of endoplasmic reticulum stress response. Overall, our results indicate that the combined regimen of bortezomib and LDM might be a potential therapeutic remedy for the treatment of MM.

Potent antitumor actions of the new antibiotic boningmycin through induction of apoptosis and cellular senescence.

Boningmycin, a new antibiotic of the bleomycin family, is isolated from the fermentation broth of Streptomyces verticillus var. pingyangensis n.sp. This study aimed to evaluate its antitumor actions and mechanism. The results showed that boningmycin exhibited potent inhibitory effects on several human solid tumor cells and that it was stronger than bleomycin. The administration of boningmycin inhibited the growth of human hepatoma HepG2 xenografts in nude mice, with more efficacy than that of bleomycin. Boningmycin led to an increase of the reactive oxygen species involving iron and caused G2/M phase accumulation in the HepG2 and human breast cancer MCF-7 cells. Two types of cell death, apoptosis and senescence, were detected after exposure to boningmycin. The accumulation of sub-G1 phase cells, an index of apoptosis, and the activation of caspase apoptotic pathways were detected after treatment with higher concentrations of boningmycin. Low concentrations of boningmycin led to a senescent phenotype with an increase in senescence-associated ß-galactosidase activity and the time-dependent increase of p21, p27, and p53 expressions from 48 to120 h. Taken together, the results showed that boningmycin exhibits potent antitumor actions through the induction of apoptosis and cellular senescence.

[Lidamycin inhibits the proliferation of HERG K+ channel highly expressing cancer cells and shows synergy with anticancer drugs].

This study is to investigate inhibitory effects of lidamycin (LDM) on the proliferation of HERG K+ channel highly expressing cancer cells and its synergy with anticancer drugs. MTT assay was used to examine the inhibitory effects of lidamycin combined with various anticancer drugs on the proliferation of human lung cancer A549 cells, human colon cancer HT-29 cells and herg-stably-transfected A549 cells. Using the xenograft model of subcutaneously transplanted HT-29 in nude mice, inhibitory effect was appraised in vivo. The coefficient of drug interaction (CDI) was used to evaluate the synergistic effect of drug combination. LDM significantly inhibited the proliferation ofA549 cells and HT-29 cells with IC50 values of 2.14 and 4.64 ng mL(-1), respectively. The efficacy in HT-29 cells with high HERG potassium expression level is less potent than that in A549 cells with low expression level. In terms of IC50 values, LDM suppressed the growth of herg-stably-transfected A549 cells less potently than pCDNA3.1-stably-transfected A549 cells. There existed synergistic effects in the combinations of fluorouracil (5-FU) and LDM, doxorubicin (DOX) and LDM, or hydroxycamptothecine (HCPT) and LDM. CDI values of the combinations of 5-FU and LDM were more than 0.75. CDI values of LDM and DOX were more than 0.70, but some CDI values of LDM and HCPT were less than 0.70. As for the CDI values, synergistic effects of the combination of LDM and HCPT were the most potent of the three groups. There is no relationship between the inhibitory effect of the growth of cancer cells by 5-FU and HERG potassium expression level. HERG expression level negatively correlated with inhibitory effect on the proliferation of cancer cells by DOX. HERG expression levels and chemosensitivity were positively correlated for HCPT. In the model of subcutaneously xenograft transplanted HT-29 in vivo, LDM and/or HCPT effectively inhibited the growth of HT-29 in nude mice, and the optimum CDI of the combination of LDM and HCPT was less than 1. HERG expression level negatively correlates the chemosensitivity of cancer cells to LDM. There exist synergistic effects in vitro and in vivo in the combination of LDM and HCPT, which inhibitory effects of the proliferation of cancer cells positively modulated by HERG potassium expression level. HERG K+ channel may become a target of combined therapy for choosing anticancer drugs.

Rhein lysinate suppresses the growth of tumor cells and increases the anti-tumor activity of Taxol in mice.

In previous studies, rhein, one of the major bioactive constituents in the rhizome of rhubarb, inhibited the proliferation of various human cancer cells. However, because of its water insolubility, the anti-tumor efficacy of rhein was limited in vivo. In this study, we observed the anti-tumor activity of rhein lysinate (the salt of rhein and lysine easily dissolves in water) in vivo and investigated its mechanism. Inhibition of ovarian cancer SKOV-3 cell proliferation was determined by MTT assay and the mechanism of action of rhein lysinate was investigated by Western blot analysis. The therapeutic efficacy of rhein lysinate was evaluated by intragastric and intraperitoneal administrations in H22 hepatocellular carcinoma mice. Rhein lysinate inhibited the proliferation of SKOV-3 cells and the IC50 value was 80 microM. Rhein lysinate inhibited the phosphorylation of MEK and ERK and increased the anti-tumor activity of Taxol in vitro. It inhibited tumor growth by both intragastric and intraperitoneal administrations and improved the therapeutic effect of Taxol in H22 hepatocellular carcinoma mice. In conclusion, rhein lysinate offers an anti-tumor activity in vivo and is hopeful to be a chemotherapeutic drug.

Generation and antitumor effects of an engineered and energized fusion protein VL-LDP-AE composed of single-domain antibody and lidamycin.

Type IV collagenase plays a pivotal role in invasion, metastasis and angiogenesis of tumor. Single domain antibodies are attractive as tumor-targeting vehicle because of their much smaller size compared with antibody molecules produced by conventional methods. Lidamycin (LDM) is a potent enediyne-containing antitumor antibiotic. In this study an engineered and energized fusion protein VL-LDP-AE composed of lidamycin and VL domain of mAb 3G11 directed against type IV collagenase was prepared using a novel two-step method. First a VL-LDP fusion protein was constructed by DNA recombination. Secondly VL-LDP-AE was obtained by molecular reconstitution. In MTT assay, VL-LDP-AE showed potent cytotoxicity to HT-1080 cells and KB cells with IC(50) values of 8.55 x 10(-12) and 1.70 x 10(-11) mol/L, respectively. VL-LDP-AE showed antiangiogenic activity in chick chrorioallantoic membrane (CAM) assay and tube formation assay. In in vivo experiments, VL-LDP-AE was proved to be more effective than free LDM against the growth of subcutaneously transplanted hepatoma 22 in mice. Drugs were given intravenously on day 3 and 10 after tumor transplantation. Compared in terms of maximal tolerated doses, VL-LDP-AE at 0.25 mg/kg suppressed the tumor growth by 89.5%, LDM at 0.05 mg/kg by 69.9%, and mitomycin at 1 mg/kg by 35%. Having a molecular weight of 25.2 kDa, VL-LDP-AE was much smaller than other reported antibody-based drugs. The results suggested that VL-LDP-AE would be a promising candidate for tumor targeting therapy. And the 2-step approach could serve as a new technology platform for making a series of highly potent engineered antibody-based drugs for a variety of cancers.

[Antitumor activities of various immunoconjugates composed of lidamycin and anti-type IV collagenase monoclonal antibody].

This study is to investigate the antitumor activities of the immunoconjugates composed of anti-type IV collagenase monoclonal antibody 3G11 and lidamycin (LDM) prepared by different methods. The immunoconjugates were prepared by linking 2-iminothiolane modified 3G11 to lysine-69 of LDM apoprotein by SPDP and SMBS as the intermediate drug linker. Immunoreactivity of the conjugates was determined by ELISA. The cytotoxicity of the conjugates was examined by clonogenic assay. Antitumor effects of the conjugates in vivo were evaluated in nude mice bearing subcutaneously implanted HT-1080 tumor. ELISA assay showed that the immunoconjugates retained the immunoreactivity of 3G11 against type IV collagenase. The cytotoxicity of the 3G11-SMBS-LDM to HT-1080 cells was significantly more potent than that of free LDM and 3G11-SPDP-LDM. In animal model at the same condition, free LDM inhibited the growth of HT-1080 tumor by 71.2%, while 3G11-SPDP-LDM and 3Gl1-SMBS-LDM reached 77.1% and 86.1%, respectively. The median survival time of the mice treated with free LDM was prolonged by 71.9% compared with that of untreated group. Whereas, the median survival time of 3G11-SPDP-LDM and 3G11-SMBS-LDM was prolonged by 125.3% and 163.7%, respectively, indicating that 3G11-SMBS-LDM was more effective than 3G11-SPDP-LDM in tumor suppression and life span prolongation. 3Gll-SMBS-LDM has more selective antitumor efficacy and lower toxicity, and might be a novel candidate for cancer therapy. LDM was more effective than 3G11-SPDP-LDM in tumor suppression and life span prolongation. 3Gll-SMBS-LDM has more selective antitumor efficacy and lower toxicity, and might be a novel candidate for cancer therapy.

A new HDAC inhibitor cinnamoylphenazine shows antitumor activity in association with intensive macropinocytosis.

Previous studies have shown that intensive macropinocytosis occurs in cancer cells and neutral red (NR) is noted for its capability to enter into the cell massively through a process mimetic to macropinocytosis. In addition, trans-cinnamic acid (tCA) has been found to be an inhibitor of histone deacetylase (HDAC). In the present study, cinnamoylphenazine (CA-PZ) that consists of NR and tCA moieties was synthesized and evaluated. As shown, CA-PZ massively entered into colon carcinoma HT-29 cells and pancreatic carcinoma MIA PaCa-2 cells and this entry was blocked by 5-(N-ethyl-N-isopropyl) amiloride (EIPA, an inhibitor of macropinocytosis), indicating a macropinocytosis-mediated uptake. Furthermore, CA-PZ markedly increased the protein expression levels of acetyl-H3, acetyl-H4 and p21 in HT-29 cells and MIA PaCa-2 cells. CA-PZ significantly inhibited the growth of colon carcinoma HT-29 and pancreatic carcinoma MIA PaCa-2 xenografts. By in vivo imaging, CA-PZ displayed prominent accumulation in the tumor xenografts. The study indicates that the newly synthesized CA-PZ acts as an HDAC inhibitor in association with intensive macropinocytosis-mediated intracellular delivery in cancer cells. The use of neutral red for preparation of chimeric molecules with the attribute of macropinocytosis-mediated intracellular delivery might open an alternative way for development of HDAC inhibitors.

Inhibition of histone deacetylases by trans-cinnamic acid and its antitumor effect against colon cancer xenografts in athymic mice.

Previous studies have shown that trans-cinnamic acid (tCA) has a broad spectrum of biological activities, and exhibits antioxidant, anti-inflammatory and anticancer properties. In addition, tCA and a variety of its analogs have been detected as gut microbe­derived metabolites exerting various biological effects in the colon. The aim of this study was to assess the antitumor activity of tCA in vitro and in vivo, in particular its therapeutic efficacy against colon cancer xenografts in athymic mice. Furthermore, it aimed to examine the effects of tCA on histone deacetylases (HDACs) and to identify the underlying molecular mechanisms. Using an MTT assay, tCA was observed to inhibit the proliferation of several cancer cell lines, and the half maximal inhibitory concentration (IC50) in HT29 colon carcinoma cells was ~1 mM. Western blot analysis demonstrated that tCA upregulated the expression of acetyl­H3 and acetyl­H4 proteins, which was consistent with the effects of the HDAC inhibitor, trichostatin A (TSA). Furthermore, expression of Bcl­2 (a marker of cell proliferation) was reduced, and apoptosis was induced. Apoptosis was shown by the activation of cleavage of poly ADP ribose polymerase and the increased expression of Bax. Apoptosis was also confirmed using APC Annexin V and SYTOX Green Nucleic Acid Stain. In addition, the tCA­induced inhibition of the expression of HDAC markers and activation of apoptosis in tumor tissues were further confirmed by immunohistochemistry. Intragastric administration of tCA at doses of 1.0 and 1.5 mmol/kg body weight suppressed the growth of HT29 human colon carcinoma xenografts in athymic mice at well­tolerated doses. No toxic changes were found in the heart, lung, liver, kidney, colon or bone marrow following histopathological examination. This study indicated that tCA is effective against colon cancer xenograft in nude mice. The antitumor mechanism of tCA was mediated, at least in part, by inhibition of HDACs in cancer cells. As an endogenous microbial metabolite predominantly produced in the colon, tCA is an agent of interest for further evaluation.

Antitumor efficacy of lidamycin against human multiple myeloma RPMI 8226 cells and the xenograft in nonobese diabetic/severe combined immunodeficiency mice.

AIMS: The aim of this study is to explore the antitumor efficacy of lidamycin (LDM) against human multiple myelomas (MM). MATERIALS AND METHODS: Human MM RPMI 8226 cells and the xenograft model in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice were used to examine the antitumor activity of LDM. RESULTS: Notably, LDM markedly suppressed the growth of human MM RPMI 8226 xenograft in NOD/SCID mice. In vitro, there was a significant reduction in cell proliferation after treatment with LDM. The overall growth inhibition correlated with the increase of apoptotic cells. The apoptosis-related proteins including caspase-3, 7, and 9 were activated, and poly adenosine diphosphate-ribose polymerase was cleaved. Further investigation revealed that cellular Bcl-2 and survivin decreased, whereas the level of Bax increased in the LDM-treated cells. CONCLUSIONS: LDM is highly effective against the growth of MM xenograft in NOD/SCID mice. The potent apoptosis.inducing effect of LDM may be mediated through caspase. and mitochondria.dependent pathway.

A recombinantly tailored ß-defensin that displays intensive macropinocytosis-mediated uptake exerting potent efficacy against K-Ras mutant pancreatic cancer.

K-Ras mutant pancreatic cancer cells display intensive macropinocytosis, indicating that this process may be exploited in the design of anticancer targeted therapies. In this study, we constructed a macropinocytosis-oriented recombinantly tailored defensin (DF-HSA) which consists of human ß-defensin-2 (DF) and human serum albumin (HSA). The macropinocytosis intensity and cytotoxicity of DF-HSA were investigated in K-Ras mutant MIA PaCa-2 cells and wild-type BxPC-3 cells. As found, the DF-HSA uptake in MIA PaCa-2 cells was much higher than that in wild-type BxPC-3 cells. Correspondingly, the cytotoxicity of DF-HSA to MIA PaCa-2 cells was more potent than that to BxPC-3 cells. In addition, the cytotoxicity of DF-HSA was much stronger than that of ß-defensin HBD2. DF-HSA suppressed cancer cell proliferation and induced mitochondrial pathway apoptosis. Notably, DF-HSA significantly inhibited the growth of human pancreatic carcinoma MIA PaCa-2 xenograft in athymic mice at well tolerated dose. By in vivo imaging, DF-HSA displayed a prominent accumulation in the tumor. The study indicates that the recombinantly tailored ß-defensin can intensively enter into the K-Ras mutant pancreatic cancer cells through macropinocytosis-mediated process and exert potent therapeutic efficacy against the pancreatic carcinoma xenograft. The novel format of ß-defensin may play an active role in macropinocytosis-mediated targeting therapy.

A Novel Nitrobenzoate Microtubule Inhibitor that Overcomes Multidrug Resistance Exhibits Antitumor Activity.

Multidrug resistance is a major limitation for microtubule-binding agents in cancer treatment. Here we report a novel microtubule inhibitor (2-morpholin-4-yl-5-nitro-benzoic acid 4-methylsulfanyl-benzyl ester, IMB5046), its cytotoxicity against multidrug-resistant cell lines and its antitumor efficacy in animal models. IMB5046 disrupted microtubule structures in cells and inhibited purified tubulin polymerization in vitro. It bound to the colchicine pocket of tubulin. IMB5046 displayed potent cytotoxicity against multiple tumor cell lines with an IC50 range of 0.037-0.426 µM. Notably, several multidrug-resistant cell lines which were resistant to colchicine, vincristine and paclitaxel remained sensitive to IMB5046. IMB5046 was not a P-glycoprotein substrate. IMB5046 blocked cell cycle at G2/M phase and induced cell apoptosis. Microarray assay indicated that the differentially expressed genes after IMB5046 treatment were highly related to immune system, cell death and cancer. In a mouse xenograft model IMB5046 inhibited the growth of human lung tumor xenograft by 83% at a well-tolerated dose. It is concluded that IMB5046 is a tubulin polymerization inhibitor with novel chemical structure and can overcome multidrug resistance. It is a promising lead compound for cancer chemotherapy, especially for treatment of multidrug-resistant tumors.

Antitumor efficacy of lidamycin on hepatoma and active moiety of its molecule.

AIM: To study the in vitro and in vivo antitumor effect of lidamycin (LDM) on hepatoma and the active moiety of its molecule. METHODS: MTT assay was used to determine the growth inhibition of human hepatoma BEL-7402 cells, SMMC-7721 cells and mouse hepatoma H22 cells. The in vivo therapeutic effects of lidamycin and mitomycin C were determined by transplantable hepatoma 22 (H22) in mice and human hepatoma BEL-7402 xenografts in athymic mice. RESULTS: In terms of IC(50) values, the cytotoxicity of LDM was 10 000-fold more potent than that of mitomycin C (MMC) and adriamycin (ADM) in human hepatoma BEL-7402 cells and SMMC-7721 cells. LDM molecule consists of two moieties, an aproprotein (LDP) and an enediyne chromophore (LDC). In terms of IC(50) values, the potency of LDC was similar to LDM. However, LDP was 10(5)-fold less potent than LDM and LDC to hepatoma cells. For mouse hepatoma H22 cells, the IC(50) value of LDM was 0.025 nmol/L. Given by single intravenous injection at doses of 0.1, 0.05 and 0.025 mg/kg, LDM markedly suppressed the growth of hepatoma 22 in mice by 84.7%, 71.6% and 61.8%, respectively. The therapeutic indexes (TI) of LDM and MMC were 15 and 2.5, respectively. By 2 iv. injections in two experiments, the growth inhibition rates by LDM at doses of 0.1, 0.05, 0.025, 0.00625 and 0.0125 mg/kg were 88.8-89.5%, 81.1-82.5%, 71.2-74.9%, 52.3-59.575%, and 33.3-48.3%, respectively. In comparison, MMC at doses of 5, 2.5, and 1.25 mg/kg inhibited tumor growth by 69.7-73.6%, 54.0-56.5%, and 31.5-52.2%, respectively. Moreover, in human hepatoma BEL-7402 xenografts, the growth inhibition rates by LDM at doses of 0.05 mg/kg X2 and 0.025 mg/kg X2 were 68.7% and 27.2%, respectively. However, MMC at the dose of 1.25 mg/kg X2 showed an inhibition rate of 34.5%. The inhibition rate of tumor growth by LDM was higher than that by MMC at the tolerated dose. CONCLUSION: Both LDM and its chromophore LDC display extremely potent cytotoxicity to hepatoma cells. LDM shows a remarkable therapeutic efficacy against murine and human hepatomas in vivo.

Antitumor activity of anti-type IV collagenase monoclonal antibody and its lidamycin conjugate against colon carcinoma.

AIM: Type IV collagenase including MMP-2 and -9 plays an important role in cancer cell invasion and metastasis and is an attractive target for mAb-directed therapy. The immunoreactivity of mAb 3G11, a mAb directed against type IV collagenase in human colorectal carcinomas, was studied by immuno-histochemical (IHC) staining. mAb 3G11 was conjugated to an antitumor antibiotic lidamycin (LDM). The antitumor activity of 3G11-LDM conjugate against colon carcinoma was investigated in mice. METHODS: ELISA, gelatin zymography, and Western blot assay were used for the biological characterization of mAb 3G11. The immunoreactivity of mAb 3G11 with human colorectal carcinomas was detected by IHC staining. The cytotoxicity of LDM and 3G11-LDM conjugate to human colon carcinoma HT-29 cells was examined by clonogenic assay and MTT assay. The therapeutic effect of conjugate 3G11-LDM was evaluated with colon carcinoma 26 in mice. RESULTS: As shown in ELISA, mAb 3G11 reacted specifically with type IV collagenase, while 3G11-LDM conjugate also recognized specifically its respective antigen. In IHC assay, mAb 3G11 showed positive immunoreactivity in most cases of colorectal carcinoma, and negative immunoreactivity in the adjacent non-malignant tissues. By gelatin zymography, the inhibition effect of mAb 3G11 on the secretion activity of type IV collagenase was proved. In terms of IC50 values in MTT assay, the cytotoxicity of LDM to human colon carcinoma HT-29 cells was 10,000-fold more potent than that of mitomycin C (MMC) and adriamycin (ADM). 3G11-LDM conjugate also displayed extremely potent cytotoxicity to human colon carcinoma HT-29 cells with an IC50 value of 5.6 x 10(-19) mol/L. 3G11-LDM conjugate at the doses of 0.05 and 0.1 mg/kg inhibited the growth of colon carcinoma 26 in mice by 70.3 and 81.2%, respectively. CONCLUSION: mAb 3G11 is immunoreactive with human colorectal carcinoma and its conjugate with LDM is highly effective against colon carcinoma in mice.

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.

A Gelatinases-targeting scFv-based Fusion Protein Shows Enhanced Antitumour Activity with Endostar against Hepatoma.

Gelatinases play important roles in tumour invasion and metastasis and are thus considered promising targets for cancer therapy. In this study, a new single-chain variable fragment (scFv)-based fusion protein Fv-LDP, composed of the anti-gelatinases scFv and lidamycin apoprotein (LDP), was prepared, and its combination with angiogenesis inhibitor Endostar was then investigated. The fusion protein Fv-LDP specifically bound to various tumour cells, and its binding capability to human pulmonary giant cell carcinoma (PG) cells was higher than that of LDP. Fv-LDP inhibited the expression and secretion of gelatinases and could be internalized into tumour cells via endocytosis. Fv-LDP also suppressed the growth of human hepatoma cells and murine hepatoma 22 transplanted in Kunming mice in various degrees. In addition, Endostar could enhance the synergistic or additive inhibition of Fv-LDP on the growth, migration or invasion of human hepatoma cells shown by a colony formation assay and a transwell-based migration or invasion assay, respectively. In vivo, Fv-LDP/Endostar combination showed a significantly synergistic effect on the growth of a human hepatoma xenograft, with an inhibition rate of 80.8% compared with the Fv-LDP (44.1%) or Endostar (8.9%)-treated group. The above-mentioned results indicate that the fusion protein Fv-LDP is effective against transplantable hepatoma in mice and human hepatoma xenografts in athymic mice. Moreover, Endostar can potentiate the inhibition effect of Fv-LDP on the growth of human hepatoma cells and xenografts. These data will provide a new combined strategy for improving the therapeutic efficacy of treatments for hepatoma or other gelatinase-overexpressing tumours.