Development of a novel multi-functional integrated bioconjugate effectively targeting K-Ras mutant pancreatic cancer.

Folate receptor (FR) overexpression occurs in a variety of cancers, including pancreatic cancer. In addition, 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.

The recombinant defensin/HSA fusion protein that inhibits NF-κb associated with intensive macropinocytosis shows potent efficacy against pancreatic cancer.

KRAS mutation and NF-κB both play crucial role in pancreatic cancer; in addition, defensin, the peptide mediator in innate immunity, can inhibit NF-κB. Assuming a strategy that targets both NF-κB and concomitantly the mutated KRAS indirectly via intensive macropinocytosis, we designed and generated a recombinant protein DF2-HSA which consists of two molecules of human beta-defensin 2 (HBD2) and a moiety of human serum albumin (HSA). As shown, the recombinant protein DF2-HSA markedly down-regulated NF-κB in both KRAS mutant MIA PaCa-2 cells and wild type BxPC-3 cells. Determined by confocal microscopy, the uptake of DF2-HSA in MIA PaCa-2 cells was more intense than that in BxPC-3 cells. The uptake was blocked by the specific inhibitor EIPA, indicating that DF2-HSA internalized via macropinocytosis. DF2-HSA displayed more potent cytotoxicity to cancer cells than HBD2. DF2-HSA induced apoptosis in cancer cells. Notably, DF2-HSA inhibited tumor cell spheroid formation, an effect comparable to that of salinomycin. DF2-HSA inhibited tumor cell migration and invasion. As detected with scanning electron microscopy, DF2-HSA strongly depleted filopodia on cell surface; and salinomycin induced similar changes. By in vivo imaging, DF2-HSA displayed intense tumor-site accumulation and lasting retention for over 14 days; however, HBD2 showed much less tumor-site accumulation and a shorter retention time for only 24 h. DF2-HSA suppressed the growth of pancreatic cancer MIA PaCa-2 xenograft in athymic mice; and its combination with gemcitabine achieved higher antitumor efficacy. In summary, the recombinant defensin/HSA fusion protein that inhibits NF-κb associated with intensive macropinocytosis is highly effective against pancreatic cancer.

Pingyangmycin enhances the antitumor efficacy of anti-PD-1 therapy associated with tumor-infiltrating CD8+ T cell augmentation.

PURPOSE: To investigate the antitumor efficacy of pingyangmycin (PYM) in combination with anti-PD-1 antibody and determine the capability of PYM to induce immunogenic cell death (ICD) in cancer cells. METHODS: The murine 4T1 breast cancer and B16 melanoma models were used for evaluation of therapeutic efficacy of the combination of PYM with anti-PD-1 antibody. The ELISA kits were used to quantify the ICD related ATP and HMGB1 levels. The Transwell assay was conducted to determine the chemotaxis ability of THP-1 cell in vitro. The flow cytometry was used to measure reactive oxygen species level and analyze the ratio of immune cell subsets. RESULTS: PYM induced ICD in murine 4T1 breast cancer and B16 melanoma cells and increased the release of nucleic acid fragments that may further promote the monocytic chemotaxis. In the 4T1 murine breast cancer model, PYM alone, anti-PD-1 antibody alone, and their combination suppressed tumor growth by 66.3%, 16.1% and 77.6%, respectively. PYM markedly enhanced the therapeutic efficacy of anti-PD-1 antibody against 4T1 breast cancer. The calculated CDI (coefficient of drug interaction) indicated synergistic effect. Evaluated by graphic analysis, the nucleated cells intensity in the femur bone marrow remained unchanged. Histopathological observations revealed no noticeable toxico-pathological changes in the lung and various organs, indicating that the PYM and anti-PD-1 antibody combination exerted enhanced efficacy at well-tolerated dosage level. By the combination treatment, a panel of immunological changes emerged. The ratio of CD3+ cells, NK cells and NKT cells increased and Tregs decreased in peripheral blood. The DCs increased in the spleen. Prominent changes occurred in tumor infiltrating lymphocytes. The ratio of CD8+ cells increased, while that of CD4+ cells decreased; however, the ratio of CD3+ cells remained unchanged, implying that certain immunological responses emerged in the tumor microenvironment. PYM alone could also increase CD8+ cells and reduce CD4+ cells in tumor infiltrating lymphocytes. CONCLUSIONS: The studies indicate that PYM, as an ICD inducer with mild myelosuppression effect, may enhance the therapeutic efficacy of anti-PD-1 antibody in association with tumor infiltrating CD8+ T cell augmentation.

DBDx-based drug combinations show highly potent therapeutic efficacy against human pancreatic cancer xenografts in athymic mice.

Previous studies have shown that DBDx, a combination consisting of dipyridamole, bestatin and dexamethasone is highly effective against several cancer xenografts in athymic mice. Here the therapeutic effects of DBDx and its combination with gemcitabine or capcitabine against human pancreatic cancer xenografts and the mechanism were studied. In vivo experiments performed in athymic mice showed that the antitumor efficacy of DBDx was much stronger than that of gemcitabine or capecitabine alone. Notably, the combination of DBDx and gemcitabine or capcitabine further enhanced the efficacy. In the case of DBDx (242 mg/kg) plus gemcitabine (100 mg/kg), tumor weight decreased about 97.7%, and tumor sizes were shrinking during the treatment. In the case of DBDx (242 mg/kg) plus capecitabine (718.7 mg/kg), tumor weight decreased about 94.9%. Moreover, DBDx and its combinations obviously prolonged theoverall survival of mice compared with gemcitabine or capcitabine alone. DBDx-based drug combination therapy showed no obvious systematic toxicity. The gene expression profile analysis showed that the genes changed by DBDx were related to immune system and tumor vasculature. The result of protein array showed that the changed proteins in the serum of treated mice were related to immune and inflammation system. These results show that DBDx-based drug combinations, a new strategy which integrates the use of low-cytotoxic drugs and cytotoxic chemotherapeutics, are highly effective regimens against human pancreatic cancer in athymic mice at well tolerated doses. DBDx-based drug combination therapy might provide new options for the treatment of pancreatic cancer.

The novel quinolizidine derivate IMB-HDC inhibits STAT5a phosphorylation at 694 and 780 and promotes DNA breakage and cell apoptosis via blocking STAT5a nuclear translocation.

Sophoridine is a quinolizidine natural product and the exploration of its derivatives has been carried out, and the potent anticancer compound IMB-HDC was acquired. Although previous studies have revealed that some sophoridine derivatives could induce DNA breakage, the underlying mechanisms of inhibition of DNA damage repair (ATR inactivation) and the apoptosis independent of p53, have not been elucidated. Our research reveals a novel DNA response mechanism different from general DNA-damaging agents, and that sophoridine derivate inhibits the phosphorylation of Tyr694 and Ser780 of STAT5a to induce the lessened shuttle from the cytoplasm to the nucleus, and leads to the decreased nuclear STAT5a and subsequently inhibits the expression of STAT5a target gene RAD51 that contributes to the checkpoint activation, thus inhibiting ATR activation. Meanwhile, IMB-HDC that induced the diminished expression of STAT5a target gene contributes to proliferation and leads to apoptosis. More importantly, we give the first evidence that promoting the effect of Tyr694 phosphorylation on nuclear location and subsequent STAT5a target gene transcription depends on Ser780 increased or unchanged phosphorylation and was not correlated with Ser726 phosphorylation.

Dexamethasone enhances the antitumor efficacy of Gemcitabine by glucocorticoid receptor signaling.

Gemcitabine (Gem) is currently used as the first-line therapy for liver and pancreatic cancer but has limited efficacy in most cases. Dexamethasone (Dex) have been applied as a chemoprotectant and chemosensitizer in cancer chemotherapy. This study further explored the potential of combination of Gem and Dex and tested the hypothesis that glucocorticoid receptor signaling is essential for the synergistic antitumor activity. In the HepG2 and AsPC-1 xenograft models, the combination treatment showed a significantly synergistic antitumor activity. Immunohistochemistry of post-treatment tumors showed a significant decrease in proliferation and angiogenesis as compared to either of the treatments alone. Dex alone and the combination with Gem inhibited the expression of glucocorticoid receptor. The combination of Dex and Gem showed synergistic cytotoxicity in cell lines in vitro. The antiproliferative synergism is prevented by used glucocorticoid receptor (GR) small interfering RNA, demonstrating that the glucocorticoid receptor is required for the antiproliferative synergism of Gem and Dex. The inhibition of glucocorticoid receptor signaling pathway and induction of apoptosis via activation of caspases 3, 8 and 9, PARP, contributed to the synergistic effect of this combination therapy. These results demonstrate that Dex could potentiate the antitumor efficacy of Gem. The synergistic antitumor activity of the combination of Dex and Gem was through glucocorticoid receptor signaling. Taken together, a combination of Dex and Gem shows a significant synergistic antitumor activity and lesser toxicity both in vitro and in vivo and could be a combination chemotherapy for the treatment of highly expression of glucocorticoid receptor patients.

The ionophore antibiotic gramicidin A inhibits pancreatic cancer stem cells associated with CD47 down-regulation.

BACKGROUND: Pancreatic cancer stem cells (CSCs), a special population of cells, renew themselves infinitely and resist to various treatment. Gramicidin A (GrA), an ionophore antibiotic derived from microorganism, can form channels across the cell membrane and disrupt cellular ionic homeostasis, leading to cell dysfunction and death. As reported, the ionophore antibiotic salinomycin (Sal) has been proved to kill CSCs effectively. Whether GrA owns the potential as a therapeutic drug for CSCs still remains unknown. This study investigated the effect of GrA on pancreatic CSCs and the mechanism. METHODS: Tumorsphere formation assay was performed to assess pancreatic CSCs self-renewal potential. In vitro hemolysis assay was determined to test the borderline concentration of GrA. CCK-8 assay was used to detect pancreatic cancer cell proliferation capability. Flow cytometry was performed to detect cell apoptosis and mitochondrial membrane potential. Scanning and transmission electron microscopy was used to observe ultrastructural morphological changes on cell membrane surface and mitochondria, respectively. Western blot analysis was used to determine relative protein expression levels. Immunofluorescence staining was performed to observe CD47 re-distribution. RESULTS: GrA at 0.05 µM caused tumorspheres disintegration and decrease in number of pancreatic cancer BxPC-3 and MIA PaCa-2 cells. GrA and Sal both inhibited cancer cell proliferation. The IC50 values of GrA and Sal for BxPC-3 cells were 0.025 µM and 0.363 µM; while for MIA PaCa-2 cells were 0.032 µM and 0.163 µM, respectively. Compared on equal concentrations, the efficacy of GrA was stronger than that of Sal. GrA at 0.1 µM or lower did not cause hemolysis. GrA induced ultrastructural changes, such as the decrease of microvilli-like protrusions on cell surface membrane and the swelling of mitochondria. GrA down-regulated the expression levels of CD133, CD44, and CD47; in addition, CD47 re-distribution was observed on cell surface. Moreover, GrA showed synergism with gemcitabine in suppressing cancer cell proliferation. CONCLUSIONS: The study found that GrA was highly active against pancreatic CSCs. It indicates that GrA exerts inhibitory effects against pancreatic CSCs associated with CD47 down-regulation, implying that GrA might play a positive role in modulating the interaction between macrophages and tumor cells.

An EGFR-targeting antibody-drug conjugate LR004-VC-MMAE: potential in esophageal squamous cell carcinoma and other malignancies.

Epidermal growth factor receptor (EGFR) is a rational target for cancer therapy, because its overexpression plays an important oncogenic role in a variety of solid tumors; however, EGFR-targeted antibody-drug conjugate (ADC) therapy for esophageal squamous cell carcinoma (ESCC) is exceedingly rare. LR004 is a novel anti-EGFR antibody with the advantages of improved safety and fewer hypersensitivity reactions. It may be of great value as a carrier in ADCs with high binding affinity and internalization ability. Here, we prepared an EGFR-targeting ADC, LR004-VC-MMAE, and evaluated its antitumor activities against ESCC and EGFR-positive cells. LR004 was covalently conjugated with monomethyl auristatin E (MMAE) via a VC linker by antibody interchain disulfide bond reduction. VC-MMAE was conjugated with LR004 with approximately 4.0 MMAE molecules per ADC. LR004-VC-MMAE showed a potent antitumor effect against ESCC and other EGFR-positive cells with IC50 values of nM concentrations in vitro. The in vivo antitumor effects of LR004-VC-MMAE were investigated in ESCC KYSE520 and A431 xenograft nude mice models. Significant activity was seen at 5 mg·kg-1 , and complete tumor regression was observed at 15 mg·kg-1 in the KYSE520 xenograft nude mice after four injections, while the naked antibody LR004 had little effect on inhibiting tumor growth. Similar promising results were obtained in the A431 models. In addition, the tumors also remained responsive to LR004-VC-MMAE for large tumor experiments (tumor volume 400-500 mm3 ). The study results demonstrated that LR004-VC-MMAE could be a potential therapeutic agent for ESCC and other EGFR-expressing malignancies. We also evaluated PK profile of LR004-VC-MMAE ADC in the mice model, which would provide qualitative guiding significance for the further research.

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.

Non-suicidal self-injury in Chinese heroin-dependent patients receiving methadone maintenance treatment: Prevalence and associated factors.

BACKGROUND: To date, there have been no studies examining non-suicidal self-injury (NSSI) in Chinese heroin-dependent patients (HDPs) receiving methadone maintenance treatment (MMT). This study determined the prevalence of NSSI and its methods in HDPs under MMT as well as factors significantly associated with NSSI. METHOD: We recruited a cross-sectional sample of 652 HDPs from three MMT clinics in Wuhan, China. In total, 603 HDPs (92.5%) completed standardized questionnaires concerning demographic, clinical, and psychosocial data. The presence and methods of NSSI were assessed with two standardized questions. RESULTS: The one-month prevalence of NSSI in Chinese HDPs receiving MMT was 13.8%. The most common three methods of NSSI were burning (59%), cutting (19.3%), and hitting (9.6%). Significant factors associated with NSSI in multiple logistic regression analysis were unemployment (OR [95%CI] = 2.54 [1.26, 5.10], P = 0.009), a short duration of MMT (OR [95%CI] = 1.04 [1.01, 1.09], P = 0.034), pain (OR [95%CI] = 2.31 [1.05, 5.35], P = 0.028), depression (OR [95%CI] = 4.32 [2.09, 9.00], P < 0.001), anxiety (OR [95%CI] = 3.74 [1.61, 8.70], P = 0.002), and loneliness (OR [95%CI] = 3.04 [1.27, 7.26], P = 0.012). CONCLUSIONS: NSSI is common among Chinese HDPs of MMT clinics. Services for HDPs in MMT settings should include periodic screening for NSSI, adequate pain treatment, and appropriate psychosocial treatment for depression, anxiety, and loneliness.

Intensive fibrosarcoma-binding capability of the reconstituted analog and its antitumor activity.

Fibrosarcomas are highly aggressive malignant tumors. It is urgently needed to explore targeted drugs and modalities for more effective therapy. Matrix metalloproteinases (MMPs) play important roles in tumor progression and metastasis, while several MMPs are highly expressed in fibrosarcomas. In addition, tissue inhibitor of metalloproteinase 2 (TIMP2) displays specific interaction with MMPs. Therefore, TIMP2 may play an active role in the development of fibrosarcoma-targeting agents. In the current study, a TIMP2-based recombinant protein LT and its enediyne-integrated analog LTE were prepared; furthermore, the fibrosarcoma-binding intensity and antitumor activity were investigated. As shown, intense and selective binding capability of the protein LT to human fibrosarcoma specimens was confirmed by tissue microarray. Moreover, LTE, the enediyne-integrated analog of LT, exerted highly potent cytotoxicity to fibrosarcoma HT1080 cells, induced apoptosis, and caused G2/M arrest. LTE at 0.1 nM markedly suppressed the migration and invasion of HT1080 cells. LTE at tolerated dose of 0.6 mg/kg inhibited the tumor growth of fibrosarcoma xenograft in athymic mice. The study provides evidence that the TIMP2-based reconstituted analog LTE may be useful as a targeted drug for fibrosarcome therapy.

Mithramycin-loaded mPEG-PLGA nanoparticles exert potent antitumor efficacy against pancreatic carcinoma.

Previous studies have shown that mithramycin A (MIT) is a promising candidate for the treatment of pancreatic carcinoma through inhibiting transcription factor Sp1. However, systemic toxicities may limit its clinical application. Here, we report a rationally designed formulation of MIT-loaded nanoparticles (MIT-NPs) with a small size and sustained release for improved passive targeting and enhanced therapeutic efficacy. Nearly spherical MIT-NPs with a mean particle size of 25.0±4.6 nm were prepared by encapsulating MIT into methoxy poly(ethylene glycol)-block-poly(d,l-lactic-co-glycolic acid) (mPEG-PLGA) nanoparticles (NPs) with drug loading of 2.11%±0.51%. The in vitro release of the MIT-NPs lasted for >48 h with a sustained-release pattern. The cytotoxicity of MIT-NPs to human pancreatic cancer BxPC-3 and MIA Paca-2 cells was comparable to that of free MIT. Determined by flow cytometry and confocal microscopy, the NPs internalized into the cells quickly and efficiently, reaching the peak level at 1-2 h. In vivo fluorescence imaging showed that the prepared NPs were gradually accumulated in BxPC-3 and MIA Paca-2 xenografts and retained for 168 h. The fluorescence intensity in both BxPC-3 and MIA Paca-2 tumors was much stronger than that of various tested organs. Therapeutic efficacy was evaluated with the poorly permeable BxPC-3 pancreatic carcinoma xenograft model. At a well-tolerated dose of 2 mg/kg, MIT-NPs suppressed BxPC-3 tumor growth by 96%. Compared at an equivalent dose, MIT-NPs exerted significantly higher therapeutic effect than free MIT (86% versus 51%, P<0.01). Moreover, the treatment of MIT and MIT-NPs reduced the expression level of oncogene c-Myc regulated by Sp1, and notably, both of them decreased the protein level of CD47. In summary, the novel formulation of MIT-NPs shows highly therapeutic efficacy against pancreatic carcinoma xenograft. In addition, MIT-NPs can downregulate CD47 expression, implying that it might play a positive role in cancer immunotherapy.

Recombinant EGFR/MMP-2 bi-targeted fusion protein markedly binding to non-small-cell lung carcinoma and exerting potent therapeutic efficacy.

Overexpression of EGFR and MMP-2 plays an essential role in the initiation and progression of non-small-cell lung carcinoma (NSCLC). In this study, a novel format of EGFR/MMP-2 bi-targeted fusion protein Ec-LDP-TIMP2 and its enediyne-integrated analogue Ec-LDP(AE)-TIMP2 have been prepared by genetic engineering and molecular reconstitution. The Ec-LDP(AE)-TIMP2 comprises endogenous inhibitor of matrix metalloproteinase 2 (TIMP2), EGF-derived oligopeptide (Ec), lidamycin apoprotein (LDP), and the extremely potent cytotoxic enediyne (AE). By tissue microarray, Ec-LDP-TIMP2 showed high binding intensity and selectivity to human NSCLC specimens as compared with the matched non-cancerous tissues. By in vivo imaging, Ec-LDP-TIMP2 displayed prominent tumor-specific distribution in human NSCLC H460 xenograft. Particularly, Ec-LDP(AE)-TIMP2 inhibited tumor growth of H460 xenograft in athymic mice more striking. At doses of 0.2 and 0.4mg/kg, Ec-LDP(AE)-TIMP2 suppressed tumor growth by 74% and 89%, respectively. No histopathological changes were found in various organs of treated animals, suggesting that the effective dosage was tolerated. In summary, the ligand-based and enediyne-integrated fusion protein displaying extremely potent cytotoxicity might be highly effective for NSCLC therapy and useful as a carrier for drug delivery.

A CD13-targeting peptide integrated protein inhibits human liver cancer growth by killing cancer stem cells and suppressing angiogenesis.

CD13 is a marker of angiogenic endothelial cells, and recently it is proved to be a biomarker of human liver cancer stem cells (CSCs). Herein, the therapeutic effects of NGR-LDP-AE, a fusion protein composed of CD13-targeting peptide NGR and antitumor antibiotic lidamycin, on human liver cancer and its mechanism were studied. Western blot and immunofluorescence assay demonstrated that CD13 (WM15 epitope) was expressed in both human liver cancer cell lines and vascular endothelial cells, while absent in normal liver cells. MTT assay showed that NGR-LDP-AE displayed potent cytotoxicity to cultured tumor cell lines with IC50 values at low nanomolar level. NGR-LDP-AE inhibited tumorsphere formation of liver cancer cells, and the IC50 values were much lower than that in MTT assay, indicating selectively killing of CSCs. In endothelial tube formation assay, NGR-LDP-AE at low cytotoxic dose significantly inhibited the formation of intact tube networks. Animal experiment demonstrated that NGR-LDP-AE inhibited the growth of human liver cancer xenograft. Immunohistochemical analysis showed that NGR-LDP-AE induced the down-regulation of CD13. In vitro experiment using cultured tumor cells also confirmed this result. NGR-LDP-AE activated both apoptotic and autophagic pathways in cultured tumor cells, while the induced autophagy protected cells from death. Conclusively, NGR-LDP-AE exerts its antitumor activity via killing liver CSCs and inhibiting angiogenesis. With one targeting motif, NGR-LDP-AE acts on both liver CSCs and angiogenic endothelial cells. It is a promising dual targeting fusion protein for liver cancer therapy, especially for advanced or relapsed cancers.

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.

An engineered TIMP2-based and enediyne-integrated fusion protein for targeting MMP-14 shows potent antitumor efficacy.

Recent studies have shown that MMP-14 is highly expressed in a panel of human solid tumors and poses as a potential molecular target for anticancer drugs. Currently, major strategies for targeted therapeutics have mainly focused on the use of antibody or ligand-based agents. For seeking an alternative approach, it is of interest to employ endogenous proteins as drug delivery carriers. Considering the facts that TIMP2, the tissue inhibitor of metalloproteinase 2, shows specific interaction with MMP-14 and that Lidamycin (LDM), an extremely potent cytotoxic antitumor antibiotic, consists of an apoprotein (LDP) and a highly active enediyne (AE); we designed and prepared a TIMP2-based and enediyne-integrated fusion protein LDP(AE)-TIMP2 by DNA recombination and molecular reconstitution consecutively. Furthermore, the MMP-14 binding attributes of the active fusion protein were determined and its therapeutic efficacy against human esophageal carcinoma KYSE150 xenograft and human fibrosarcoma HT1080 xenograft models in nude mice was investigated. It is suggested that TIMP2, the endogenous and MMP-14 binding protein, might serve as a guided carrier for targeted therapeutics.

A multifunctional drug combination shows highly potent therapeutic efficacy against human cancer xenografts in athymic mice.

The tumor microenvironment plays a crucial role during tumor development. Integrated combination of drugs that target tumor microenvironment is a promising approach to anticancer therapy. Here, we report a multifunctional combination of low-cytotoxic drugs composed of dipyridamole, bestatin and dexamethasone (DBDx) which mainly acts on the tumor microenvironment shows highly potent antitumor efficacy in vivo. In mouse hepatoma H22 model, the triple drug combination showed synergistic and highly potent antitumor efficacy. The combination indices of various combinations of the triple drugs were between 0.2 and 0.5. DBDx inhibited the growth of a panel of human tumor xenografts and showed no obvious systemic toxicity. At tolerated doses, DBDx suppressed the growth of human hepatocellular carcinoma BEL-7402, HepG2, and lung adenocarcinoma A549 xenografts by 94.5%, 93.7% and 96.9%, respectively. Clonogenic assay demonstrated that DBDx showed weak cytotoxicity. Western blot showed that Flk1 and Nos3 were down-regulated in the DBDx-treated group. Proteomic analysis showed that DBDx mainly affected the metabolic process and immune system process; in addition, the angiogenesis and VEGF signaling pathway were also affected. Conclusively, DBDx, a multifunctional drug combination of three low-cytotoxic drugs, shows synergistic and highly potent antitumor efficacy evidently mediated by the modulation of tumor microenvironment. Based on its low-cytotoxic attributes and its broad-spectrum antitumor therapeutic efficacy, this multifunctional combination might be useful in the treatment of cancers, especially those refractory to conventional chemotherapeutics.

Tuftsin-based, EGFR-targeting fusion protein and its enediyne-energized analog show high antitumor efficacy associated with CD47 down-regulation.

Tuftsin (TF) is an immunomodulator tetrapeptide (Thr-Lys-Pro-Arg) that binds to the receptor neuropilin-1 (Nrp1) on the surface of cells. Many reports have described anti-tumor activity of tuftsin to relate with nonspecific activation of the host immune system. Lidamycin (LDM) that displays extremely potent cytotoxicity to cancer cells is composed of an apoprotein (LDP) and an enediyne chromophore (AE). In addition, Ec is an EGFR-targeting oligopeptide. In the present study, LDP was used as protein scaffold and the specific carrier for the highly potent AE. Genetically engineered fusion proteins LDP-TF and Ec-LDP-TF were prepared; then, the enediyne-energized fusion protein Ec-LDM-TF was generated by integration of AE into Ec-LDP-TF. The tuftsin-based fusion proteins LDP-TF and Ec-LDP-TF significantly enhanced the phagocytotic activity of macrophages as compared with LDP (P < 0.05). Ec-LDP-TF effectively bound to tumor cells and macrophages; furthermore, it markedly suppressed the growth of human epidermoid carcinoma A431 xenograft in athymic mice by 84.2 % (P < 0.05) with up-regulated expression of TNF-α and IFN-γ. Ec-LDM-TF further augmented the therapeutic efficacy, inhibiting the growth of A431 xenograft by 90.9 % (P < 0.05); notably, the Ec-LDM-TF caused marked down-regulation of CD47 in A431 cells. Moreover, the best therapeutic effect was recorded in the group of animals treated with the combination of Ec-LDP-TF with Ec-LDM-TF. The results suggest that tuftsin-based, enediyne-energized, and EGFR-targeting fusion proteins exert highly antitumor efficacy with CD47 modulation. Tuftsin-based fusion proteins are potentially useful for treatment of EGFR- and CD47-overexpressing cancers.

MMP-2/9-oriented combinations enhance antitumor efficacy of EGFR/HER2-targeting fusion proteins and gemcitabine.

To increase the antitumor efficacy, in the present study, we proposed several settings of matrix metalloproteinase (MMP)-2/9-oriented combinations that comprise the MMP-2/9-targeting fusion protein dFv-LDP and the MMP inhibitor doxycycline (DOX) in association with EGFR/HER2-bispecific fusion protein Ec-LDP-Hr, its enediyne-energized analogue Ec-LDP-Hr-AE, and gemcitabine (GEM). The expressions of various fusion proteins were detected by western blot analysis. Proliferation and migration inhibition of cells were determined by MTT and Transwell assay, respectively. The binding capability of dFv-LDP and Ec-LDP-Hr to cancer cells was examined by ELISA, cell immunofluorescence coimmunoprecipitation and confocal assays. Animal experiments were set to investigate the antitumor efficacy of various combinations against colorectal carcinoma HCT-15 xenograft in athymic mice. These two targeting proteins dFv-LDP and Ec-LDP-Hr had strong binding capabilities and antiproliferation effects on various cancer cell lines. Enhanced therapeutic efficacy in vivo was observed in the MMP-2/9-targeting fusion protein dFv-LDP integrated combinations including: i) dFv-LDP and Ec-LDP-Hr, ii) dFv-LDP and enediyne-energized fusion protein Ec-LDP-Hr-AE, iii) dFv-LDP and Ec-LDP-Hr-AE plus DOX, and iv) dFv-LDP and GEM plus DOX against colorectal cancer HCT-15 xenograft in athymic mice. In setting iii, DOX (20 mg/kg), dFv-LDP (20 mg/kg) and Ec-LDP-Hr-AE (0.3 mg/kg) alone suppressed tumor growth by 35, 49.7 and 67.5%, respectively. The combination of dFv-LDP and Ec-LDP-Hr-AE was 75.1%. Furthermore, this combination plus DOX showed stronger efficacy with an inhibitory rate of 82.7%. In setting iv, the combination of dFv-LDP and GEM suppressed tumor growth by 66.3%. Notably, the tumor inhibitory rate of the dFv-LDP/GEM/DOX combination reached 85.5%, producing initial shrinkage after the first administration. The MMP-2/9-oriented combination strategy that employs the MMP-2/9-targeting antibody-based fusion protein and the small molecular inhibitor DOX as the basic composed agents may enhance antitumor efficacy in association with the EGFR/HER2-targeting fusion protein and GEM. This multiple targeting approach may be useful for enhancing antitumor efficacy against colorectal cancer.

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.