Heru Chen

Pericyte-targeting prodrug overcomes tumor resistance to vascular disrupting agents

Blood vessels in the tumor periphery have high pericyte coverage and are resistant to vascular disrupting agents (VDAs). VDA treatment resistance leads to a viable peripheral tumor rim that contributes to treatment failure and disease recurrence. Here, we provide evidence to support a hypothesis that shifting the target of VDAs from tumor vessel endothelial cells to pericytes disrupts tumor peripheral vessels and the viable rim, circumventing VDA treatment resistance. Through chemical engineering, we developed Z-GP-DAVLBH (from the tubulin-binding VDA desacetylvinblastine monohydrazide [DAVLBH]) as a prodrug that can be selectively activated by fibroblast activation protein α (FAPα) in tumor pericytes. Z-GP-DAVLBH selectively destroys the cytoskeleton of FAPα-expressing tumor pericytes, disrupting blood vessels both within the core and around the periphery of tumors. As a result, Z-GP-DAVLBH treatment eradicated the otherwise VDA-resistant tumor rim and led to complete regression of tumors in multiple lines of xenografts without producing the drug-related toxicity that is associated with similar doses of DAVLBH. This study demonstrates that targeting tumor pericytes with an FAPα-activated VDA prodrug represents a potential vascular disruption strategy in overcoming tumor resistance to VDA treatments.

Synthesis of xanthone derivatives and studies on the inhibition against cancer cells growth and synergistic combinations of them

34 Xanthones were synthesized by microwave assisted technique. Their inxa0vitro inhibition activities against five cell lines growth were evaluated. The SAR has been thoroughly discussed. 7-Bromo-1,3-dihydroxy-9H-xanthen-9-one (3-1) was confirmed as the most active agent against MDA-MB-231xa0cell line growth with an IC50 of 0.46xa0±xa00.03xa0μM. Combination of 3-1 and 5,6-dimethylxanthone-4-acetic acid (DMXAA) showed the best synergistic effect. Apoptosis analysis indicated different contributions of early/late apoptosis and necrosis to cell death for both monomers and the combination. Western Blot implied that the combination regulated p53/MDM2 to a better healthy state. Furthermore, 3-1 and DMXAA arrested more cells on G2/M phase; while the combination arrested more cells on S phase. All the evidences support that the 3-1/DMXAA combination is a better anti-cancer therapy.

Elaboration of thorough simplified vinca alkaloids as antimitotic agents based on pharmacophore similarity

Thorough simplification of vinca alkaloids based on pharmacophore similarity has been conducted. A concise process for the syntheses of target compounds was successfully developed with yields from poor to excellent (19-98%). Cell growth inhibitory activities of these synthesized compounds were evaluated in five cancer cell lines including MCF-7, MDA-MB-231, HepG2, HepG2/ADM and K562. Almost all compounds exhibited moderate antitumor activity with optimal IC50 value of 0.89 ± 0.07 μM in MCF-7 cells. Investigation of structure-activity relationship (SAR) indicates that electron-withdraw substituents on the ring contribute to the enhancement of the antitumor activities. The simplified vinca alkaloids are confirmed as antimitotic agents, which inhibit the polymerization of tubulin just like vinblastine.

Desacetylvinblastine monohydrazide disrupts tumor vessels by promoting VE-cadherin internalization

Vinca alkaloids, the well-known tubulin-binding agents, are widely used for the clinical treatment of malignant tumors. However, little attention has been paid to their vascular disrupting effects, and the underlying mechanisms remain largely unknown. This study aims to investigate the vascular disrupting effect and the underlying mechanisms of vinca alkaloids. Methods: The capillary disruption assay and aortic ring assay were performed to evaluate the in vitro vascular disrupting effect of desacetylvinblastine monohydrazide (DAVLBH), a derivate of vinblastine, and the in vivo vascular disrupting effect was assessed on HepG2 xenograft model using magnetic resonance imaging, hematoxylin and eosin staining and immunohistochemistry. Tubulin polymerization, endothelial cell monolayer permeability, western blotting and immunofluorescence assays were performed to explore the underlying mechanisms of DAVLBH-mediated tumor vascular disruption. Results: DAVLBH has potent vascular disrupting activity both in vitro and in vivo. DAVLBH disrupts tumor vessels in a different manner than classical tubulin-targeting VDAs; it inhibits microtubule polymerization, promotes the internalization of vascular endothelial cadherin (VE-cadherin) and inhibits the recycling of internalized VE-cadherin to the cell membrane, thus increasing endothelial cell permeability and ultimately resulting in vascular disruption. DAVLBH-mediated promotion of VE-cadherin internalization and inhibition of internalized VE-cadherin recycling back to the cell membrane are partly dependent on inhibition of microtubule polymerization, and Src activation is involved in DAVLBH-induced VE-cadherin internalization. Conclusions: This study sheds light on the tumor vascular disrupting effect and underlying mechanisms of vinca alkaloids and provides new insight into the molecular mechanism of tubulin-targeting VDAs.

Short Simple Linear Peptides Mimic Antimicrobial ComplexCyclodecapeptides Based on the Putative Pharmacophore

The sequence, -D-Tyr-Pro-Trp-D-Phe- has been identified from Loloatin C as a promising pharmacophore model for developing new antimicrobial peptides. Most of the linear peptides designed based on this sequence exhibits strong antimicrobial activities against Gram-positive bacteria S. aureus , S. albus and Gram-negative bacteria E. coli strains with MIC values ranging from 15.6 to 62.5 μg/mL, although they are inactive against fungus C. albicans , multi-drug resistant bacterial MRSA and K. pneumoniae . The linear hexapeptide, H-Asp-D-Tyr-Pro-Trp-D-Phe-Asn-OH (L1) is confirmed the most active peptide among them. L1 possesses s table α-helix domain conformation which is similar to Loloatin C in membrane mimetic solution. All the tested peptides demonstrate low hemolytic toxicity to rabbit red blood cells with EC 50 values higher than 120 μg/mL and low cytotoxicity to mouse fibroblast cells. The successful simplication of Loloatin C to a short linear peptide simplifies the synthetic process and lowers costs of production. The discussion of structure-activity relationship is also included

A vascular disrupting agent overcomes tumor multidrug resistance by skewing macrophage polarity toward the M1 phenotype

Multidrug resistance (MDR) mediated by ATP-binding cassette (ABC) transporters is the major obstacle for chemotherapeutic success. Although attempts have been made to circumvent ABC transporter-mediated MDR in past decades, there is still no effective agent in clinic. Here, we identified a vascular disrupting agent, Z-GP-DAVLBH, that significantly inhibited the growth of multidrug-resistant human hepatoma HepG2/ADM and human breast cancer MCF-7/ADR tumor xenografts, although these cells were insensitive to Z-GP-DAVLBH inxa0vitro. Z-GP-DAVLBH increased the secretion of granulocyte-macrophage colony-stimulating factor in tumor tissues and serum of tumor-bearing mice to skew tumor-associated macrophages from the pro-tumor M2 phenotype to the antitumor M1 phenotype, thereby contributing to the induction of HepG2/ADM and MCF-7/ADR cell apoptosis. Our findings shed new light on the underlying mechanisms of VDAs in the treatment of drug-resistant tumors and provide strong evidence that Z-GP-DAVLBH should be a promising agent for overcoming MDR.

DMXAA-pyranoxanthone hybrids enhance inhibition activities against human cancer cells with multi-target functions

Four 5,6-dimethylxanthone-4-acetic acid (D) and pyranoxanthone (P) hybrids (D-P-n) were design-synthesized based on multi-target-addressed strategy. D-P-4 was confirmed as the most active agent against HepG-2xa0cell line growth with an IC50 of 0.216xa0±xa00.031xa0μM. Apoptosis analysis indicated different contributions of early/late apoptosis/necrosis to cell death for both monomers, the combination (Dxa0+xa0P in 1:1xa0mol ratio) and D-P-4. They all arrested more cells on S phase. Western Blot implied that D-P-4 regulated p53/MDM2 to a better healthy state. Moreover, it improved Bax/Bcl-2 signaling pathway to increase cancer cell apoptosis. In all cases studied, D-P-4 showed the best activity and synergistic effect. All the evidences support that D-P-4 is a better anti-cancer therapy with multi-target functions.

Incorporation of nitric oxide donor into 1,3-dioxyxanthones leads to synergistic anticancer activity

Fifty 1,3-dioxyxanthone nitrates (4au202f∼u202fi-n, nu202f=u202f1-6) were designed and synthesized based on molecular similarity strategy. Incorporation of nitrate into 1,3-dioxyxanthones with electron-donating groups at 6-8 position brought about synergistic anticancer effect. Among them, compound 4g-4 was confirmed the most active agent against HepG-2u202fcells growth with an IC50 of 0.33u202f±u202f0.06u202fμM. It dose-dependently increased intramolecular NO levels. This activity was attenuated by either NO scavenger PTIO or mitochondrial aldehyde dehydrogenase (mtADH) inhibitor PCDA. Apoptosis analysis indicated different contributions of early/late apoptosis and necrosis to cell death for different dose of 4g-4. 4g-4 arrested more cells on S phase. Results from Western Blot implied that 4g-4 regulated p53/MDM2 to promote cancer cell apoptosis. All the evidences support that 4g-4 is a promising anti-cancer agent.