Greater Cytotoxicity Research Articles

Elucidation of cellular uptake and intracellular trafficking of heparosan polysaccharide-based micelles in various cancer cells.

Heparosan polysaccharide, known as a heparin precursor, can be used in drug delivery systems due to its good biocompatibility and anti-cancer effect. But few studies on the cellular uptake mechanism of heparosan polysaccharide-based nanocarrier have been investigated. Therefore, the intracellular trafficking and the uptake mechanism of heparosan-based micelles by different tumor cells were investigated in this study. Heparosan-cholesterol amphipathic conjugates (KC) were constructed and doxorubicin (DOX) was loaded to prepare DOX/KC micelles. Different cancer cells were selected to find out the influence on DOX/KC uptake. There was an obvious difference in cytotoxicity and cellular uptake of DOX/KC in various cancer cells. Interestingly, DOX/KC micelles exhibited the strongest cytotoxicity against MGC80-3 cells and displayed highly cellular uptake by B16 cells. The results of the uptake mechanism showed that the internalization of DOX/KC micelles into MGC80-3 cells and A549 cells was mainly through clathrin-mediated endocytosis and macropinocytosis, while micropinocytosis, clathrin-mediated endocytosis and clathrin/caveolae -independent multi-pathways all contributed to the uptake of micelles in B16 cells. Furthermore, after being internalized by MGC80-3 cells, DOX/KC could escape from the lysosome and simultaneously be transported into the nucleus and mitochondria resulting in the greatest cytotoxicity. These results indicate that heparosan-based drug delivery systems may have different uptake and subcellular distribution behavior in tumor cells, and they will achieve the maximum efficacy only in specific kind of cancers.

Cancer Cells Treated by Clusters of Copper Oxide Doped Calcium Silicate.

Purpose: Different compositions of copper oxide (CuO)-doped calcium silicate clusters were used to treat the cancer cells. Methods: The influence of CuO content on the morphology, drug delivering ability, physicochemical properties and cytotoxicity was investigated. Results: The microcrystalline structure revealed the decrement of the size from (20-36 nm) to (5-7 nm) depending on the copper content percentages. Drug delivering ability of doxycycline hyclate (Dox) was down regulated from 58% to 28%in the presence of the CuO. The inclusion of CuO and Dox didn’t show any remarkable changes on the physicochemical properties of the CuO-doped calcium silicate nanoparticles. Conclusion: The CuO-doped calcium silicate sample (5 weight %) exhibited great cytotoxicity against the tested cell lines compared to the CuO-free sample. CuO-doped materials displayed significant anticancer effect; this sheds light on its implication in the treatment of cancer.

Synthesis and characterisation of a new benzamide-containing nitrobenzoxadiazole as a GSTP1-1 inhibitor endowed with high stability to metabolic hydrolysis

The antitumor agent 6-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)thio)hexan-1-ol (1) is a potent inhibitor of GSTP1-1, a glutathione S-transferase capable of inhibiting apoptosis by binding to JNK1 and TRAF2. We recently demonstrated that, unlike its parent compound, the benzoyl ester of 1 (compound 3) exhibits negligible reactivity towards GSH, and has a different mode of interaction with GSTP1-1. Unfortunately, 3 is susceptible to rapid metabolic hydrolysis. In an effort to improve the metabolic stability of 3, its ester group has been replaced by an amide, leading to N-(6-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)thio)hexyl)benzamide (4). Unlike 3, compound 4 was stable to human liver microsomal carboxylesterases, but retained the ability to disrupt the interaction between GSTP1-1 and TRAF2 regardless of GSH levels. Moreover, 4 exhibited both a higher stability in the presence of GSH and a greater cytotoxicity towards cultured A375 melanoma cells, in comparison with 1 and its analog 2. These findings suggest that 4 deserves further preclinical testing.

Type of pH sensitive linker reveals different time-dependent intracellular localization, in vitro and in vivo efficiency in alpha-fetoprotein receptor targeted doxorubicin conjugate

Despite the presence of a variety of modern anticancer drugs at the market, doxorubicin (Dox) is still widely used in antineoplastic therapy, although its administration causes severe side effects. To enhance specific activity of such molecules, various approaches have been exploited: targeted moieties like monoclonal antibodies, onco-specific proteins and peptides are utilized as specific vector molecules; environment sensitive linkers are exploited to facilitate transported drug release at the target point etc. Acid-labile linkers are frequently used in synthesis due to the ability to be cleaved inside specific cellular compartments with acidic environment, avoiding possible recycling mechanisms. Two types of conjugates containing different acid-labile linkers have been synthesized. In vitro efficiency of doxorubicin conjugates with recombinant receptor-binding domain of human alpha-fetoprotein (3dAFPpG) synthesized with use of cis-aconitic anhydride (CAA) and linker based on succinimidyl 3-(2-pyridyldithio)propionate (SPDP) and 3-(2-pyridyldithio)propionic acid hydrazide (PDPH) was compared. The 3dAFPpG-SPDP-PDPH-Dox revealed a comparable with unmodified doxorubicin cytotoxic effect against the Dox sensitive MCF7 cell line and greater cytotoxicity against the anthracycline resistant MCF7Adr cells. Meanwhile the 3dAFPpG-CAA-Dox cytotoxic effect was significantly lower, although doxorubicin’s pH-dependent release profiles and intracellular accumulation rates were similar. These differences in cytotoxic activity were arguably explained by the dissimilarities in intracellular doxorubicin localization, which may originate from thiol reductase activity in lysosomes and late endosomes.

Developing a novel cholesterol-based nanocarrier with high transfection efficiency and serum compatibility for gene therapy

Primary cells are sensitive to culture conditions, which can be more difficult to get efficient transfection. The purpose of this study is to develop a serum-compatible cholesterol-based nanocarrier for delivering therapeutic nucleic acids into cells efficiently for future clinical gene therapy. A novel cationic 3-β-[N-(2-guanidinoethyl)carbamoyl]-cholesterol (GEC-Chol) was mixed with cholesterol and superparamagnetic iron oxide (SPIO) nanoparticles to form GCC-Fe3O4 nanocarrier. Transfection efficiency and cytotoxicity in serum and non-serum conditions were evaluated. Florescent-labeled oligonucleotides (ODNs) were transfected as indicators. Fluorescent microscopy, confocal microscopy, and flow cytometry analysis were used for evaluations. Besides, we also delivered functional antisense c-myc ODNs as surrogates for specific gene manipulation in vitro. Results indicated that GCC-Fe3O4 nanocarrier could have size down to less than 135 nm, which structure was highly stable and consistent over time. It also showed great transfection efficiency and low cytotoxicity in both serum and non-serum conditions. Our results demonstrated that GCC-Fe3O4 nanocarrier had exceeded 90% transfection efficiency, which was much better than common commercialized transfection reagents under same conditions. Such nanocarrier not only worked well in cell lines, but also ideal for gene delivery in primary cells. With high transfection efficiency and serum compatibility, this novel biocompatible cholesterol-based nanocarrier provides an ideal platform especially for RNAi-based gene manipulation. It also opens a wide range of biomedical applications for in vivo cell tracking and gene therapeutics for clinical usage.

Toxin-producing Klebsiella oxytoca as a cause of antibiotic-associated colitis

Antibiotic-associated diarrhea remains an unresolved problem in current medicine. In the last decade, in addition to idiopathic antibiotic-associated diarrhea, diseases caused by cytotoxin-producing Klebsiella oxytoca strains are becoming increasingly detected. Clinical manifestations of this infection may vary from relatively mild diarrhea without signs of hemocolitis to severe antibiotic-associated hemorrhagic colitis with predominant involvement of the right hemicolon. High prevalence of resistance to ciprofloxacin, tetracycline, gentamicin, amikacyne, and trimethoprim/sulfamethoxazole is associated with the presence of all adhesion genes of K. oxytoca and its greater cytotoxicity. The genes encoding the K. oxytoca cytotoxin (tilivalline) are a part of the pathogenicity island (PAI) and are similar to the clusters responsible for the biosynthesis of pyrrolobenzodiazepine and found in gram-positive bacteria. The most important pathogenicity factor related to the development of K. oxytoca -associated hemorrhagic colitis is a cytotoxin kleboxymycin, which is a tilivalline metabolite. The treatment strategy in K. oxytoca -associated hemorrhagic colitis is to withdraw the trigger antimicrobial agent, to refrain from administration of new antimicrobials, to administer rehydration and rational pathogenetically based therapy. Studies on the development of therapeutic bacteriophages against K. oxytoca are of pilot nature.

Copanlisib, a novel phosphoinositide 3-kinase inhibitor, combined with carfilzomib inhibits multiple myeloma cell proliferation.

Multiple myeloma (MM) is a uniformly fatal disorder of B cells characterized by the accumulation of abnormal plasma cells. Phosphoinositide 3-kinase (PI3K) signaling pathways play a critical regulatory role in MM pathology. Copanlisib, also known as BAY80-6946, is a potent PI3Kα and δ inhibitor. In this study, we investigated the efficacy of copanlisib and a proteasome inhibitor using MM cell lines and primary samples. The p110α and δ catalytic subunits of the class PI3K increased, and carfilzomib activity reduced in the presence of a supernatant from the feeder cell line, HS-5. Phosphorylation of Akt and activation of caspase 3 and poly (ADP-ribose) polymerase (PARP) partially reduced upon carfilzomib treatment in the presence of HS-5. Apoptosis also decreased. Copanlisib treatment for 72h inhibited growth in MM cell lines and induced apoptosis. Combination treatment of MM cells with carfilzomib and copanlisib caused greater cytotoxicity than that caused by either drug alone and increased apoptosis. Caspase 3 activity increased while that of Akt decreased after combination treatment with copanlisib and carfilzomib. Further, copanlisib inhibited vascular endothelial growth factor (VEGF)-mediated angiogenesis in vitro and in vivo. It also inhibited C-X-C motif chemokine 12 (CXCL12)-mediated chemotaxis. The data suggest that administration of the PI3K inhibitor, copanlisib, may be a powerful strategy against stroma-associated drug resistance of MM cells and can enhance the cytotoxic effects of proteasome inhibitors in such residual MM cells.

Excelsanone, a new isoflavonoid from Erythrina excelsa (Fabaceae), with in vitro antioxidant and in vitro cytotoxic effects on prostate cancer cells lines

A new isoflavonoid, excelsanone (2), was isolated from the ethyl acetate extract of Erythrina excelsa stem bark, together with three known compounds namely 6,8-diprenylgenistein (3), β-sitosterol (1) and sitosteryl-β-D-glucopyranoside (4). Their structures were elucidated using spectroscopic methods (HR-ESI-MS, NMR and IR) and by comparison with some literature data. The antioxidant activity of crude extracts and two isolated compounds was evaluated using free radical scavenging (DPPH) and Ferric Reducing Ability Power (FRAP) methods with catechin as standard. The results of the radical scavenging activity showed that excelsanone (2) has a moderate potential with an IC50 of 1.31 mg/ml. The cytotoxicity of compounds 2 and 3 as well as the ethyl acetate extract was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in two prostate cancer cell lines (DU145 and PC3). Excelsanone (2) induced a greater cytotoxicity in all tested cell lines, with a significant inhibition of DU145 cells growth in a concentration-dependent manner.

Bufalin-loaded vitamin E succinate-grafted-chitosan oligosaccharide/RGD conjugated TPGS mixed micelles demonstrated improved antitumor activity against drug-resistant colon cancer.

BackgroundMultidrug resistance (MDR) is the major reason for the failure of chemotherapy in colon cancer. Bufalin (BU) is one of the most effective antitumor active constituents in Chansu. Our previous study found that BU can effectively reverse P-glycoprotein (P-gp)-mediated MDR in colon cancer. However, the clinical application of BU is limited due to its low solubility in water and high toxicity. In the present study, a multifunctional delivery system based on vitamin-E- succinate grafted chitosan oligosaccharide (VES-CSO) and cyclic (arginine-glycine-aspartic acid peptide) (RGD)-modified d-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS) was prepared by emulsion solvent evaporation method for targeted delivery of BU to improve the efficacy of drug-resistant colon cancer therapy.MethodsThe cytotoxicity of BU-loaded micelles against drug-resistant colon cancer LoVo/ADR and HCT116/LOHP cells was measured by CCK-8 assay. The cellular uptake, Rho123 accumulation, and cell apoptosis were determined by flow cytometry. The expression of apoptosis-related protein and P-gp was measured by Western blot assay. The antitumor activity of BU-loaded micelles was evaluated in LoVo/ADR-bearing nude mice.ResultsBU-loaded VES-CSO/TPGS-RGD mixed micelles (BU@VeC/T-RGD MM) were 140.3 nm in diameter with zeta potential of 8.66 mV. The BU@VeC/T-RGD MM exhibited good stability, sustained-release pattern, higher intracellular uptake, and greater cytotoxicity in LoVo/ADR cells. Furthermore, the mechanisms of the BU@VeC/T-RGD MM to overcome MDR might be due to enhanced apoptosis rate and P-gp efflux inhibition. Subsequently, in vivo studies confirmed an enhanced therapeutic efficiency and reduced side effects associated with BU@VeC/T-RGD MM compared with free BU, owing to the enhanced permeation and retention effect, improved pharmacokinetic behavior, and tumor targeting, which lead to MDR-inhibiting effect in LoVo/ADR-bearing nude mice.ConclusionOur results demonstrated that VeC/T-RGD MM could be developed as a potential delivery system for BU to improve its antitumor activity against drug-resistant colon cancer.

SDF-1-loaded PLGA nanoparticles for the targeted photoacoustic imaging and photothermal therapy of metastatic lymph nodes in tongue squamous cell carcinoma

The combination of photothermal therapy and targeted chemotherapy can produce much greater cytotoxicity than chemotherapy. Herein, we developed multifunctional targeted polymeric nanoparticles (NPs) loaded with indocyanine green (ICG) and doxorubicin (DOX) for the targeted photoacoustic imaging and photothermal ablation of oral cancer cells. The chemokine SDF-1, a specific antibody, was conjugated to NPs by the carbodiimide method. The NPs were automatically targeted to tumour tissue in vitro and in vivo through CXCR4-SDF-1 interactions. The results of in vivo and in vitro photoacoustic imaging and photothermal therapy experiments showed that the multifunctional NPs had excellent photoacoustic imaging characteristics and photothermal therapy capabilities. The photothermal material heated rapidly after laser irradiation, and the resulting heat increased cell metabolism and membrane permeability, which increased cellular NP uptake. The encapsulated drug (DOX) was released immediately after the liquid core was transformed into a gas via laser effects, which killed tumour cells while producing strong photoacoustic signals in vitro and in vivo. Thus, we concluded that the chemokine SDF-1 can be applied for the targeted chemotherapy of metastatic lymph nodes of oral squamous cell carcinoma (OSCC) and is more effective for treating oral cancer when combined with photothermal therapy than when used alone.

Gemcitabine combined with an engineered oncolytic vaccinia virus exhibits a synergistic suppressive effect on the tumor growth of pancreatic cancer

Pancreatic cancer (PC) is a lethal solid malignancy with resistance to traditional chemotherapy. Recently, considerable studies have demonstrated the ubiquitous antitumor properties of gene therapy mediated by the oncolytic vaccinia virus. The second mitochondrial-derived activator of caspase (Smac) has been identified as an innovative tumor suppressor that augments the chemosensitivity of cancer cells. However, the therapeutic value of oncolytic vaccinia virus (oVV)-mediated Smac gene transfer in pancreatic cancer is yet to be elucidated. In the present study, oncolytic vaccinia virus expressing Smac (second mitochondrial-derived activator of caspase) (oVV-Smac) was used to examine its beneficial value when used alone or with gemcitabine in pancreatic cancer in vitro and in vivo. The expression of Smac was evaluated by western blot analysis and quantitative polymerase chain reaction, oVV-Smac cytotoxicity by MTT assay, and apoptosis by flow cytometry and western blot analysis. Furthermore, the inhibitory effect of oVV-Smac combined with gemcitabine was also evaluated. The results indicated that oVV-Smac achieved high levels of Smac, greater cytotoxicity, and potentiated apoptosis. Moreover, co-treatment with oVV-Smac and gemcitabine resulted in a synergistic effect in vitro and in vivo. Therefore, our findings advance oVV-Smac as a potential therapeutic candidate in pancreatic cancer and indicated the synergistic effects of co-treatment with oVV-Smac and gemcitabine.

Oblongifolin C suppresses lysosomal function independently of TFEB nuclear translocation.

Lysosomes are the terminal organelles of the autophagic-endocytic pathway and play a key role in the degradation of autophagic contents. We previously reported that a natural compound oblongifolin C (OC) increased the number of autophagosomes and impaired the degradation of P62, most likely via suppression of lysosomal function and blockage of autophagosome-lysosome fusion. However, the precise mechanisms of how OC inhibits the lysosome-autophagy pathway remain unclear. In the present study, we investigated the effect of OC on transcription factor EB (TFEB), a master regulator of lysosomal biogenesis, lysosomal function and autophagy. We showed that treatment with OC (15 μM) markedly enhanced the nuclear translocation of TFEB in HeLa cells, concomitantly reduced the interaction of TFEB with 14-3-3 proteins. We further demonstrated that OC caused significant inhibition of mTORC1 along with TFEB nuclear translocation, and OC-mediated TFEB nuclear translocation was dependent on mTORC1 suppression. Intriguingly, this increased nuclear TFEB was accompanied by reduced TFEB luciferase activity, increased lysosomal pH and impaired cathepsin enzyme activities. In HeLa cells, treatment with OC (7.5 μM) resulted in about 30% of cell death, whereas treatment with hydroxycitrate, a caloric restriction mimetic (20 μM) did not affect the cell viability. However, cotreatment with OC and hydroxycitrate caused significantly great cytotoxicity (>50%). Taken together, these results demonstrate that inhibition of lysosome function is mediated by OC, despite evident TFEB nuclear translocation.

New inhibitors of matrix metalloproteinases 9 (MMP-9): Lignans from Selaginella moellendorffii

Matrix metalloproteinase 9 (MMP-9) is one of the structurally related zinc-dependent endopeptidases families and provides a new target for cancer therapy owing to its pivotal role in metastatic tumors. In this paper, fourteen lignans, including three novel lignans, named selamoellenin B–D (1–3), and eleven known lignan derivatives (4–14) were isolated from the plant of Selaginella moellendorffii. Among them, compound 3 is optically active, which was enantiomerically seperated to afford a pair of enantiomers, (−)-3 and (+)-3. Their structures were elucidated by extensive spectroscopic analyses. Their cytotoxic activities were evaluated against four human cancer cell lines. Among them, five compounds (4, 5, 6, 11 and 13) exhibited great potent cytotoxicity and their structure-activity relationships were also discussed. All compounds except for 3 lignan analogues with low cytotoxicity were selected for further in vitro enzyme inhibition, surface plasmon resonance (SPR), and molecular docking assays based on the MMPs target. The results shown that, compound 11 have the best inhibitory effect and can be considered as a potential drug candidate targeting at MMP-9 for cancer therapy.

POxylated graphene oxide nanomaterials for combination chemo-phototherapy of breast cancer cells

PEGylated graphene oxide (GO) nanomaterials have been showing promising results in cancer therapy, due to their drug loading and photothermal capacities. However, the recent reports regarding the immunogenicity of poly(ethylene glycol) based coatings highlight the importance of investigating alternative materials to functionalize GO. Herein, GO derivatives were functionalized for the first time with an amphiphilic polymer based on poly(2-ethyl-2-oxazoline) and were co-loaded with doxorubicin (DOX) and D-α-Tocopherol succinate (TOS) to be applied in chemo-phototherapy of breast cancer cells. The results revealed that POxylated GO displays the required properties for application in cancer therapy. Moreover, the screening of different DOX:TOS combination ratios showed that the 1:3 DOX:TOS molar ratio produces an optimal synergistic therapeutic effect towards breast cancer cells. Furthermore, this drug ratio had a lower impact on normal cells. POxylated GO was then loaded with this drug combination in order to assess its chemo-phototherapeutic potential. The delivery of DOX:TOS by POxylated GO to cancer cells induced a stronger therapeutic effect than that attained with the free drug combination. Furthermore, an even greater cytotoxicity towards cancer cells was achieved by exposing DOX:TOS loaded POxylated GO to near infrared radiation. Overall, POxylated GO is a promising drug delivery and phototherapeutic agent.

Cytotoxic effect of Semialarium mexicanum (Miers) Mennega root bark extracts and fractions against breast cancer cells.

The root bark of Semialarium mexicanum (Miers) Mennega (cancerina) is traditionally used in Mexico to treat cancer. However, there are no studies supporting its use. We evaluated whether S. mexicanum root bark induces cytotoxicity in breast cancer cells to determine if it has potential applications in the treatment of this disease. Extracts of S. mexicanum root bark in petroleum ether, ethanol, and water were obtained by ultrasound-assisted extraction. MTT and WST-1 assays were used to evaluate the cytotoxicity of the extracts toward breast cancer cells (MDA-MB-231 and MCF7), non-tumorigenic breast-derived cells (MCF 10A), and peripheral blood mononuclear cells (PBMCs). For the extract with greatest cytotoxicity, induction of apoptosis and oxidative stress were determined using flow cytometry. The extract was fractionated, and the cytotoxicity of its fractions was evaluated with the four cell types. The fractions were also analyzed by HPLC. Only the petroleum ether extract was cytotoxic for all cell types (MDA-MB-231 > MCF 10A/MCF7 > PBMCs). Cell death occurred by apoptosis, which could be associated with the induction of oxidative stress. Two fractions that were highly cytotoxic for breast cancer cells were obtained from this extract (IC50 ≤ 4.15µg/mL for the most active fraction at 72h). The MCF 10A cells were less affected, while PBMCs were not affected after 72h of treatment. Pristimerin was identified in both fractions and may be partially responsible for the cytotoxic effect. These results suggest that S. mexicanum root bark has a potential application in breast cancer treatment.

Abstract 3979: Active components of Alpinia katsumadai-induced cell apoptosis and autophagy in human pancreatic cancer cells

Abstract Alpinia katsumadai, as a traditional Chinese medicine, exhibited potent anti-oxidative and anticancer effects. Studies have shown that the effect of the active components of Alpinia katsumadai (ACAK) on anticancer is via apoptosis or autophagy in colorectal and glioblastoma cancer cells. However, the effects of ACAK on anticancer effect and inducation of apoptosis and autophagy in pancreatic cancer cells are still unknown. Therefore, we investigated the effects of ACAK on cytotocixity, apoptosis and autophagy as well as associated mechanisms in pancreatic cancers Panc-1 and Panc-28 cells. We found that ACAK showed greater inhibitory effects on the proliferation of Panc-1 and Panc-28 cells in a dose- and time-dependent manners (IC50 0.1692 and 0.1554mg/ml, respectively) compared to a variety of other cancer cells including breast cancer MDA-MB-468 cells, melamoma A875 cells, lung cancer A549 cells, colon cancer HCT-116 cells, and glioblastoma cancer U87 cells (IC50 0.2302, 0.2586, 0.2642, 0.3006, and 0.4298, respectively) by CCK-8 assay. Furthermore, ACAK induced cell apoptosis in pancreatic cancer Panc-1 and Panc-28 cells in a dose- dependent manner by Hochest 33342-PI and AnnexinV-PI dual staining analysis. Moreover, the expression levels of apoptosis related proteins casepase 3, casepase 9, and PARP were significantly up-regulated by Western blotting analysis. The study of cell autophagy was dectected by mRFP -GFP-LC3 adenovirus and western-blotting. and the results showed that the expression levels of autophagy-related protein beclin-1 and LC3-II were significanlt up-regulated by mRFP-GFP-LC3 adenovirus and western-blotting analysis. Our findings demonstrated that ACAK had greater cytotoxicity than a variety of other cancer cells by inducing apoptosis and autophagy in pancreatic cancer Panc-1 and Panc-28 cells. Therefore, ACAK may be developed as a novel anticancer agent for the treatment of pancreatic cancer clinically. Citation Format: Weixiao An, Honglin Lai, Yangyyang Zhang, Xiukun Lin, Shousong Cao. Active components of Alpinia katsumadai-induced cell apoptosis and autophagy in human pancreatic cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3979.

Impact of various lipophilic substituents on ruthenium(II), rhodium(III) and iridium(III) salicylaldimine-based complexes: synthesis, in vitro cytotoxicity studies and DNA interactions.

A series of bidentate salicylaldimine ligands was prepared and reacted with either [RuCl(µ-Cl)(p-cymene)]2, [RhCl(µ-Cl)(Cp*)]2 or [IrCl(µ-Cl)(Cp*)]2. All of the compounds were characterised using an array of spectroscopic and analytical techniques, namely, nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy and mass spectrometry. Single crystal X-ray diffraction (XRD) was used to confirm the bidentate coordination mode of the salicylaldimine ligand to the metal centre. The platinum group metal (PGM) complexes were screened against the MCF7 breast cancer cell line. The ruthenium and iridium salicylaldimine complexes showed comparable or greater cytotoxicity than cisplatin against the MCF7 cancer cells, as well as greater cytotoxicity than their rhodium counterparts. Three of the salicylaldimine complexes showed potent activity in the range 18-21µM. Two of these complexes had a greater affinity for cancerous cells than for CHO non-cancerous cells (SI > 4). Preliminary mechanistic studies suggest that the ruthenium complexes undergo solvation prior to 5'-GMP binding, whereas the iridium complexes were inert to the solvation process.

Enhanced delivery of sorafenib with anti-GPC3 antibody-conjugated TPGS-b-PCL/Pluronic P123 polymeric nanoparticles for targeted therapy of hepatocellular carcinoma

Although sorafenib (SFB) showed improved efficacy and much reduced the side effects in clinical liver cancer therapy, its therapeutic efficacy was still greatly limited due to short half-life in vivo as well as drug resistance. To solve these problems, we developed a novel SFB-loaded polymeric nanoparticle for targeted therapy of liver cancer. This polymeric nanoparticle, referred to NP-SFB-Ab, was fabricated from self-assembly of biodegradable block copolymers TPGS-b-poly(caprolactone) (TPGS-b-PCL) and Pluronic P123 and drug SFB, followed by conjugating the anti-GPC3 antibody. NP-SFB-Ab showed robust stability and achieve excellent SFB release in cell medium. The CLSM demonstrated that the Ab-conjugated NP exhibited much higher cellular uptake in HepG2 human liver cells than non-targeted NP. The MTT assay also confirmed that NP-SFB-Ab caused much greater cytotoxicity than non-targeted NP-SFB and free SFB. Finally, NP-SFB-Ab was proved to greatly inhibit the tumor growth of HepG2 xenograft-bearing nude mice without obvious side effects. Therefore, this NP-SFB-Ab provides a promising new approach for targeted therapy of hepatocellular carcinoma.

Bilirubin Nanoparticle-Assisted Delivery of a Small Molecule-Drug Conjugate for Targeted Cancer Therapy.

Despite growing interest in targeted cancer therapy with small molecule drug conjugates (SMDCs), the short half-life of these conjugates in blood associated with their small size has limited their efficacy in cancer therapy. In this report, we propose a new approach for improving the antitumor efficacy of SMDCs based on nanoparticle-assisted delivery. Ideally, a nanoparticle-based delivery vehicle would prolong the half-life of an SMDC in blood and then release it in response to stimuli in the tumor microenvironment (TME). In this study, PEGylated bilirubin-based nanoparticles (BRNPs) were chosen as an appropriate delivery carrier because of their ability to release drugs in response to TME-associated reactive oxygen species (ROS) through rapid particle disruption. As a model SMDC, ACUPA-SN38 was synthesized by linking the prostate-specific membrane antigen (PSMA)-targeting ligand, ACUPA, to the chemotherapeutic agent, SN38. ACUPA-SN38 was loaded into BRNPs using a film-formation and rehydration method. The resulting ACUPA-SN38@BRNPs exhibited ROS-mediated particle disruption and rapid release of the SMDC, resulting in greater cytotoxicity toward PSMA-overexpressing prostate cancer cells (LNCaP) than toward ROS-unresponsive ACUPA-SN38@Liposomes. In a pharmacokinetic study, the circulation time of ACUPA-SN38@BRNPs in blood was prolonged by approximately 2-fold compared with that of the SMDC-based micellar nanoparticles. Finally, ACUPA-SN38@BRNPs showed greater antitumor efficacy in a PSMA-overexpressing human prostate xenograft tumor model than SN38@BRNPs or the SMDC alone. Collectively, these findings suggest that BRNPs are a viable delivery carrier option for various cancer-targeting SMDCs that suffer from short circulation half-life and limited therapeutic efficacy.

Uranyl acetate induced DNA single strand breaks and AP sites in Chinese hamster ovary cells

The aim of this study is to characterize the genotoxicity of depleted uranium (DU) in Chinese Hamster Ovary cells (CHO) with mutations in various DNA repair pathways. CHO cells were exposed to 0–300 μM of soluble DU as uranyl acetate (UA) for 0–48 h. Intracellular UA concentrations were measured via inductively coupled mass spectrometry (ICP-MS) and visualized by transmission electron microscopy (TEM). Cytotoxicity was assessed in vitro by clonogenic survival assay. DNA damage response was assessed via Fast Micromethod® to determine UA-induced DNA single strand breaks. Results indicate that UA is entering the CHO cells, with the highest concentration localizing in the nucleus. Clonogenic assays show that UA is cytotoxic in each cell line with the greatest cytotoxicity in the base excision repair deficient EM9 cells and the nuclear excision repair deficient UV5 cells compared to the non-homologous end joining deficient V3.3 cells and the parental AA8 cells after 48 h. This indicates that UA is producing single strand breaks and forming UA-DNA adducts rather than double strand breaks in CHO cells. Fast Micromethod® results indicate an increased amount of single strand breaks in the EM9 cells after 48 h UA exposure compared to the V3.3 and AA8 cells. These results indicate that DU induces DNA damage via strand breaks and uranium-DNA adducts in treated cells. These results suggest that: (1) DU is genotoxic in CHO cells, and (2) DU is inducing single strand breaks rather than double strand breaks in vitro.