Development of a novel multi-functional integrated bioconjugate effectively targeting K-Ras mutant pancreatic cancer / 药物分析学报

Folate receptor(FR)overexpression occurs in a variety of cancers,including pancreatic cancer.In addi-tion,enhanced macropinocytosis exists in K-Ras mutant pancreatic cancer.Furthermore,the occurrence of intensive desmoplasia causes a hypoxic microenvironment in pancreatic cancer.In this study,a novel FR-directed,macropinocytosis-enhanced,and highly cytotoxic bioconjugate folate(F)-human serum albumin(HSA)-apoprotein of lidamycin(LDP)-active enediyne(AE)derived from lidamycin was designed and prepared.F-HSA-LDP-AE consisted of four moieties:F,HSA,LDP,and AE.F-HSA-LDP presented high binding efficiency with the FR and pancreatic cancer cells.Its uptake in wild-type cells was more extensive than in K-Ras mutant-type cells.By in vivo optical imaging,F-HSA-LDP displayed prominent tumor-specific biodistribution in pancreatic cancer xenograft-bearing mice,showing clear and lasting tumor localization for 360 h.In the MTT assay,F-HSA-LDP-AE demonstrated potent cytotoxicity in three types of pancreatic cancer cell lines.It also induced apoptosis and caused G2/M cell cycle arrest.F-HSA-LDP-AE markedly suppressed the tumor growth of AsPc-1 pancreatic cancer xenografts in athymic mice.At well-tolerated doses of 0.5 and 1 mg/kg,(i.v.,twice),the inhibition rates were 91.2％and 94.8％,respectively(P＜0.01).The results of this study indicate that the F-HSA-LDP multi-functional bioconjugate might be effective for treating K-Ras mutant pancreatic cancer.

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.

Synthesis and anti-angiogenic activity of a novel microtubule inhibitor IMB5046 / 药学学报

IMB5046 is a newly discovered nitrobenzoate functioning as a microtubule inhibitor. Here we report its synthesis and in vitro anti-angiogenic activity. IMB5046 was synthesized by conjugation of 2-morpholin-4-yl-5-nitrobenzoic acid with 4-(methylthio)benzyl alcohol via two-step reactions. The structure of the end product was verified using 1H NMR and HR-MS spectroscopy. The effect of these compounds on cell proliferation was determined using MTT assay, and their impact on cytoskeleton was investigated using fluorescence assay. Flow cytometry was performed to examine the effect of IMB5046 on cell cycle. Cell wound scratch assay and Transwell assay were performed to examine cell migration. Endothelial tube formation assay was used to evaluate the anti-angiogenic activity of IMB5046. The results indicated that IMB5046 induced endothelial cell contraction and microtubule depolymerization, and inhibited the proliferation of endothelial cells and tumor cells, while two raw materials showed no obvious effects. IMB5046 arrested cell cycle at G2/M phase, even at low-cytotoxic concentrations it significantly inhibited the motility of endothelial cells. IMB5046 inhibited the tube formation of endothelial cells according to the number of tubes and junctions. In conclusion, IMB5046 is a promising microtubule-targeting drug with anti-angiogenic activity.

Research progress in new anti-tumor drugs on different targets derived from microorganisms / 药学学报

The metabolites produced by complex and diverse microorganisms are important resources for drug research and development. Using new targets to screen microbial metabolites, many anti-cancer drugs acting on different targets are discovered. Anti-tumor antibiotics acting on various targets and signaling pathways are important members in the study of specific targets for anti-tumor, and some anticancer antibiotics with potent antitumor activity are used as "warheads" of antibody-drug conjugates. Microbial-derived anti-tumor substances acting on different targets with high-efficiency "warheads" molecules are reviewed to provide a literature basis for research on the anti-cancer drugs for specific targets derived from microorganisms.

Molecular targets of tea polyphenols and its roles of anticancer drugs in experimental therapy / 药学学报

Tea polyphenols (TPs), major biological active constituents of green tea, exert moderate and selective anticancer effects. Molecular mechanisms of TPs in cancer prevention and treatment involve multiple potential molecular targets. TPs inhibit growth factor receptor-mediated signal transduction pathway, decrease the activities of mitogen activated protein kinases and activator protein transcription factor-1, block nuclear factor-kappaB signaling pathway, reduce proteasome activity, lower overexpression of COX-2, subside dihydrofolate reductase and telomerase, and inhibit DNA methylation and matrix metalloproteinases. Furthermore, TPs enhance the inhibitory effect on the growth of cancers by traditional anticancer drugs or targeted antitumor drugs in vitro and in vivo and reverse multidrug resistances of cancer cells to vincristine, doxorubicin, and 5-fluorouracil. Besides, TPs reduce the nephrotoxicity induced by cisplatin, ameliorate irinotecan-induced side effects in the small intestine of mice, and decrease bleomycin-caused DNA damage in human leukocytes. TPs also increase antitumor activity of vaccine through immunological modulation. TPs play roles of the augmentation of antitumor effects, the reversal of multidrug resistance, and the reduction of side effects of chemotherapeutic drugs. TPs could be used as biochemical modulators in cancer therapy.

Isolation and culture of mouse spermatogonial stem cells and determination of the related markers / 中国医学科学院学报

<p><b>OBJECTIVE</b>To establish a simple and highly effective isolation and culture system of mouse spermatogonial stem cells(SSCs)and detect the expression of stem cell-related markers in the isolated cells.</p><p><b>METHODS</b>The structures of seminiferous tubules of neonatal(6-8 days of age)and adult(26-28 weeks)DBA/2 mice were compared using histochemical examination. Testes of neonatal mice were selected for preparing primary cells. The digestive efficiency of different enzymes was compared. SSCs were isolated according to the different binding abilities of testicle somatic cells and SSCs to gelatin matrix. The effects of different base culture media such as StemPro34 and α-MEM,gelatin,and serum on the SSCs binding activity and growth were studied. The cell morphology was observed during the culture process. Immunofluorescence was used to detect the expression of SSCs and cancer stem cells(CSCs)-related markers in SSCs.</p><p><b>RESULTS</b>The content of SSCs in the testes of neonatal mice was relatively higher than that in adult mice. Trypsin showed the highest digestive efficiency. In StemPro34 supplemented with 1% fetal bovine serum and on the gelatin matrix,testicular somatic cells could bind with the plate efficiently. Spermatogonial cells grew well when using mitomycin C-treated testicular somatic cells as feeder cells and showed typical characteristic of SSCs. After 13 days of culture,spermatogonial cells formed cell clusters. Immunofluorescence assay showed that SSCs markers glial cell line-derived neurotrophic factor(GDNF)family receptor α1(GFRα1)and VASA protein were highly expressed in the cell clusters. CSCs marker CD44 was expressed in the As,Apr,Aal and the inner cells of the cell clusters,while seldom expressed in the somatic cells.</p><p><b>CONCLUSIONS</b>An isolation and culture system of SSCs derived from DBA/2 mice was established. CD44 is highly expressed in the early stage of spermatogonial cell development.</p>

Optimization of the preparation process for fusion protein Fv-LDP that composes lidamycin apoprotein and single-chain Fv antibody directed against type IV collagenase / 药学学报

This study is to optimize the preparation process of fusion protein Fv-LDP which was expressed in the form of inclusion body and consisted of lidamycin apoprotein LDP and single-chain Fv antibody (scFv) directed against type IV collagenase. The preparation and the dissolution of inclusion body, the immobilized metal affinity chromatography of the target protein and the renaturization by stepwise dialysis were optimized by single-factor analysis or orthogonal design. In addition, the refolded fusion protein Fv-LDP was refined by Sephadex G-75 chromatography followed by fluorescence-activated cell sorter (FACS)-based saturation binding assay to measure its antigen-binding activity. After optimization of the process, the purity of fusion protein Fv-LDP existed in the inclusion body was 63.9% and the corresponding solubility was 95.7%; Under denaturing conditions, the purity of fusion protein Fv-LDP was more than 95% after the purification process. The percentage of monomeric fusion protein Fv-LDP was 60% after the refolding process, while it was further refined to 85% which was 5.6-fold higher than that of the initial refolding condition. The refined fusion protein Fv-LDP could bind to human lung adenocarcinoma PAa cells and human hepatoma BEL-7402 cells with the dissociation constants (Kd) of 0.176 micromol x L(-1) and 0.904 micromol x L(-1), respectively. The preparation process of fusion protein Fv-LDP has been successfully optimized, which provides the experimental basis for the production and future development of fusion protein Fv-LDP, and might serve as a relatively practical system for the preparation of other scFv-based proteins expressed in the form of inclusion body.

Anticancer effect of 17-(6-cinnamamido-hexylamino-)-17-demethoxygeldanamycin: in vitro and in vivo / 药学学报

In the present study, a new compound named 17-(6-cinnamamido-hexylamino-)-17-demethoxygeldanamycin (CDG) was obtained by introducing the cinnamic acid (CA) group into the 17-site of geldanamycin (GDM). The anti-cancer effects of CDG in vitro and in vivo were evaluated. MTT assay was used to examine the inhibitory effect of CDG on the proliferation of MCF-7, HepG2, H460 and SW1990 cells. Immunofluorescent staining flow cytometry combined with Annexin V-FITC/PI staining were used to detect apoptotic cells. Transwell assay was used to analyze the effect of CDG on cell invasion and migration ability. Western blotting was used to detect the expression levels of RAF-1, EGFR, AKT, CDK4 and HER-2 of MCF-7, HepG2 and H460 cells. The toxicities of CDG and GDM were evaluated in mice. Using the subcutaneously transplanted MCF-7 xenograft in nude mice, inhibitory effect was evaluated in vivo. The results showed that CDG inhibited the proliferation of cancer cells (IC50: 13.6-67.4 microg.mL-1). After exposure to CDG for 48 h, most cells presented typical morphologic changes of apoptosis such as chromatin condensation or shrunken nucleus. The rates of apoptosis of MCF-7, HepG2, H460 and SW1990 cells incubated with 10 microg.mL-1 CDG were 23.16%, 27.55%, 22.21%, 20.47%, respectively. A dose-dependent reduction of migration of four cell lines was found after exposure to CDG. The decreased levels of RAF-1, EGFR, AKT, CDK4 and HER-2 showed that CDG possessed HSP90 inhibitory effect. The result of animal toxicity test on the mice suggested that CDG had lower toxicity than GDM. Meanwhile, CDG inhibited the growth of MCF-7 xenografts of athymic mice.

Construction of IL-1Ra-HSA fusion protein and analysis of its bioactivity and pharmacokinetics / 药学学报

In order to increase the plasma half-life and tissue specificity of IL-1 receptor antagonist, a recombinant fusion protein IL-1Ra-HSA, linked by a rigid peptide linker PAPAP, was engineered and expressed by the Pichia pastoris host cells. The fusion protein was secreted to the host cells culture, identified by Western blot, and purified by affinity chromatography. This was followed by a further examination of its bioactivity and pharmacokinetics. Our results demonstrated that the fusion protein retained the antagonist activity of IL-1Ra, capable of binding specifically to the IL-1 receptor on human melanoma A375.S2 cells, and inhibits the cytolytic effect of IL-1beta to A375.S2 cells. Albumin fusion dramatically extended the half-life of IL-1Ra and resulted in a specific accumulation of IL-1Ra in the arthritic paws and a lower distribution of IL-1Ra in other organs such as liver, kidney, spleen and lung in mice with collagen-induced arthritis. The findings reported herein indicate that the fusion protein is likely to have greater clinical applications in areas such as the treatment of rheumatoid arthritis.

An overview of antibody-based cancer therapy / 药学学报

The use of monoclonal antibodies (mAbs) for cancer therapy has achieved considerable success in recent years. Approximate 17 monoclonal antibodies have been approved as cancer therapeutics since 1997. Antibody-drug conjugates (ADC) are powerful new treatment options for cancer, and naked antibodies have recently achieved remarkable success. The safety and effectiveness of therapeutic mAbs in oncology vary depending on the nature of the target antigen and the mechanisms of tumor cell killing. This review provides a summary of the current state of antibody-based cancer therapy, including the mechanisms of tumor cell killing by antibodies, tumor antigens as antibody targets, clinical effectiveness of antibodies in cancer patients and nanoparticles-based ADCs.

Inhibition of tumor cell invasion and induction of apoptosis by ubenimex / 药学学报

This study is to investigate the effects of ubenimex on tumor cell invasion and apoptosis, dose relationship and mechanism. Immunofluorescence staining was performed to detect the expression of CD13 in HT-1080 cells. MTT assay was used to analyze the effect of ubenimex on cell proliferation. Annexin V-EGFP/PI was used to detect apoptotic cells by flow cytometry. Cell cycle was analyzed using flow cytometry. Ala-pNA was used as substrate to evaluate the effect of ubenimex on the aminopeptidase activity. Transwell assay was used to analyze the effect of ubenimex on cell invasion and migration ability. Western blotting was used to detect the expression level of CD13. MMP activity was analyzed using gelatin zymography. The results showed that ubenimex at high concentration inhibited the proliferation of HT-1080 cells (IC50: 3.8 mg x mL(-1)), and induced cell apoptosis. Cell cycle was blocked at G1 phase. Ubenimex at low concentration inhibited the aminopeptidase activity of HT-1080 cells (IC50: 8.3 microg x mL(-1)) and inhibited cell invasion, but it had no effects on the cell migration and proliferation. Ubenimex had no effects on CD13 expression and MMP activity. In conclusion, ubenimex at low concentration can inhibit the invasion ability of tumor cells by directly inhibiting the aminopeptidase activity; ubenimex at high concentration can inhibit the proliferation of tumor cells and induce cell apoptosis by a CD13-independent pathway.

Bioluminescence imaging evaluation of the inhibitory effect of lidamycin on lung metastasis of human fibrosarcoma in athymic mice / 药学学报

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.

Optimization of the assembly efficiency for lidamycin chromophore bound to its apoprotein: a case study using orthogonal array / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Lidamycin inhibits the proliferation of HERG K+ channel highly expressing cancer cells and shows synergy with anticancer drugs / 药学学报

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.

Binding capability of lidamycin apoprotein to human breast cancer detected by tissue microarrays / 药学学报

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.

Construction and screening of phage antibody libraries against epidermal growth factor receptor and soluble expression of single chain Fv / 药学学报

Recent studies have shown that epidermal growth factor receptor (EGFR) is an important target for cancer therapy. The present study prepared single chain Fv (scFv) directed against EGFR. Balb/c mice were immunized by human carcinoma A431 cells, and total RNA of the splenic cells was extracted. VH and VL gene fragments were amplified by RT-PCR and further joined into scFv gene with a linker, then scFv gene fragments were ligated into the phagemid vector pCANTAB 5E. The phagemid containing scFv were transformed into electro-competent E. coli TG1 cells. The recombinant phage antibody library was constructed through rescuing the transformed cells with help phage M13K07. The specified recombinant phages were enriched through 5 rounds of affinity panning and the anti-EGFR phage scFv clones were screened and identified with ELISA. A total of 48 clones from the library were selected randomly and 45 clones were identified positive. After infecting E. coli HB2151 cells with one positive clone, soluble recombinant antibodies about 27 kD were produced and located in the periplasm and the supernatant. The result of sequencing showed that the scFv gene was 768 bp, which encoded 256 amino acid residues. VH and VL including 3 CDRs and 4 FRs, respectively, were all homologous to mouse Ig. The soluble scFv showed the specific binding activity to purified EGFR and EGFR located in carcinoma cell membrane. The successful preparation of anti-EGFR scFv will provide an EGFR targeted molecule for the development of antibody-based drugs and biological therapy of cancer.

Lidamycin induces apoptosis of human gastric carcinoma BGC823 cells and inhibits xenograft growth in nude mice / 药学学报

To investigate the effect of lidamycin (LDM) on human gastric carcinoma BGC823 cells and xenograft growth in nude mice, MTT (methyl thiazolyl tetrazolium) assay was used to determine the inhibition of BGC823 cell proliferation by LDM. Induction of apoptosis was studied by flow cytometry and TUNEL assay. The expression of VEGF was detected by Western blotting analysis. Athymic nude mice were used to determine in vivo antitumor activity. Proliferation inhibition and apoptosis induction were studied in lidamycin-treated cells. The expression of VEGF in BGC823 cells decreased in a dose-dependent manner. LDM at 0.02 mg x kg(-1) and 0.04 mg x kg(-1) suppressed the growth of BGC823 xenografts in nude mice by 57% and 72%, respectively. LDM potently induces apoptosis in human gastric carcinoma BGC823 cells and inhibits xenograft growth.

Rhein lysinate induces apoptosis in breast cancer SK-Br-3 cells by inhibiting HER-2 signal pathway / 药学学报

This study is to investigate the effect of rhein lysinate on inducing human breast cancer cell line SK-Br-3 apoptosis and the role of HER-2 signal pathway in the apoptosis. MTT assay was used to detect SK-Br-3 cell proliferation. Cell cycle and apoptosis were analyzed by flow cytometry. The protein expression and the protein phosphorylation of HER-2 signal pathway were detected by Western blotting. The level of HER-2 mRNA was detected by RT-PCR and the level of HER-2 expression was also detected by immunofluorescence cytochemical methods. The results showed that rhein lysinate remarkably inhibited breast cancer SK-Br-3 cell proliferation. The IC50 value for 48 h treatment was 85 micromol x L(-1). Apoptosis in SK-Br-3 cells was induced by rhein lysinate in a dose dependent manner. The protein expressions of HER-2, NF-KB, and the protein phosphorylation of HER-2 were downregulated, however the protein expression of p53 and p21 was upregulated after rhein lysinate treatment. The level of HER-2 mRNA decreased by using RT-PCR assay and the level of HER-2 expression was also decreased by using immunofluorescence cytochemical assay after rhein lysinate treatment. It can be concluded that rhein lysinate could inhibit SK-Br-3 cell proliferation and induce apoptosis. HER-2/NF-kappaB/p53/p21 signal pathway might be involved in this process. Rhein lysinate has a good prospect to be an adjuvant chemotherapeutic drug.

Antitumor activities of various immunoconjugates composed of lidamycin and anti-type IV collagenase monoclonal antibody / 药学学报

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.

Effect of lidamycin on telomerase activity in human hepatoma BEL-7402 cells / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate the effect of lidamycin (LDM) on telomerase activity in human hepatoma BEL-7402 cells under the condition of LDM inducing mitotic cell death and senescence.</p><p><b>METHODS</b>Chromatin condensation was detected by co-staining with Hoechst 33342 and PI. Cell multinucleation was observed by Giemsa staining and genomic DNA was separated by agarose gel electrophoresis. Fluorescent intensity of Rho123 was determined for mitochondrial membrane potential. MTT assay and SA-beta-gal staining were employed to analyze the senescence-like phenotype. The expression of proteins was analyzed by Western blot. Telomerase activity was assayed by telomerase PCR-ELISA.</p><p><b>RESULTS</b>Mitotic cell death occurred in LDM-treated cells characterized by unique and atypical chromatin condensation, multinucleation and increased mitochondrial membrane potential. However, no apoptotic bodies or DNA ladders were found. In addition, apoptosis-related proteins remained nearly unaltered. Senescence-like phenotype was identified by increased and elongated size of cells, growth retardation, enhanced SA-beta-gal activity and the changes of senescence-related protein expression. Telomerase activity markedly decreased (P<0.01) in LDM-treated hepatoma BEL-7402 cells.</p><p><b>CONCLUSION</b>Mitotic cell death and senescence could be triggered simultaneously or sequentially after exposure of hepatoma BEL-7402 cells to LDM. The decrease in telomerase activity may play a key role in the defective mitosis and aging morphology. Further investigation of detailed mechanism is needed.</p>