Chunying Cui

Novel tetrapeptide, RGDF, mediated tumor specific liposomal doxorubicin (DOX) preparations.

Arginine-glycine-aspartate (RGD) has been shown to possess a strong affinity for the integrins overexpressed in tumor cells, especially during tumor invasion, angiogenesis and metasis. Based on work from others, a novel tetrapeptide, arginine-glycine-aspartate-phenylanaline (RGDF), has been designed and studied as a homing device to direct liposomal doxorubicin (DOX) to tumor cells in this work. In order to incorporate RGDF into liposomal DOX preparations, RGDF was conjugated with three different fatty alcohols to achieve RGDF-fatty alcohol conjugates. Glycine-glycine-aspartate-phenylanaline (GGDF)-lauryl alcohol conjugate was synthesized as a negative control. RGDF-fatty alcohol conjugates (RGDFO(CH(2))(n)CH(3)) and GGDF-lauryl alcohol conjugate (L-GGDFC12-DOX) incorporated liposomal preparations were obtained by first preparing liposomes using the film dispersion method followed by loading DOX using a transmembrane pH gradient method. Because of their amphipathic nature, RGDF- or GGDF-fatty alcohol conjugates are expected to be readily incorporated into liposomes with their fatty alkanyl chains being intercalated between fatty acyl chains of liposomal bilayers and the hydrophilic peptide moiety (RGDF or GGDF) being anchored on the surface of liposomes. The particle size and zeta potential of liposomal DOX preparations containing RGDF-fatty alcohol conjugate (L-RGDF-DOXs) or L-GGDFC12-DOX were measured, and their morphology was studied using transmission electron microscopy. In vitro DOX release profile from RGDF incorporated liposomal DOX was measured. The antitumor activities of RGDF incorporated liposomal DOX preparations were evaluated in ICR mice inoculated with sarcoma S(180), which is known to express α(v)β(3) integrin. Both conventional liposomal DOX preparation (L-DOX) without RGDFO(CH(2))(n)CH(3) and L-GGDFC12-DOX were used as negative controls. Our results showed improved tumor growth inhibition with L-RGDF-DOXs over doxorubicin hydrochloride solution, L-DOX and L-GGDFC12-DOX. Pathological examination of tumor biopsy demonstrated that L-RGDF-DOXs induced enhanced tumor cell death in comparison to negative controls. Pharmacokinetic studies showed that the concentrations of DOX found in tumor sites were increased by 1.7-4.5-fold when liposomal DOX preparation containing RGDF-lauryl alcohol conjugate (L-RGDFC12-DOX) was administered in comparison to when L-GGDFC12-DOX or doxorubicin hydrochloride solution was administered. The concentrations of DOX found in the heart, which is the main site of toxic effects of DOX, were significantly reduced when L-RGDFC12-DOX was administered in comparison to when L-GGDFC12-DOX or doxorubicin hydrochloride solution was administered.

Synthesis and evaluation of anti-tumor activities of N4 fatty acyl amino acid derivatives of 1-β-arabinofuranosylcytosine

1-Beta-D-arabinofuranosylcytosine (Ara-C, Cytarabine) is one of the drugs used for acute nonlymphocytic leukemia (ANLL). However, the bioavailability of Ara-C is relatively low due to its low lipophilicity. In order to improve the lipophilicity and bioavailability of Ara-C, a series of N(4) derivatives of Ara-C, i.e., (fatty acid)-(amino acid)-Ara-C analogues, were prepared. The 15 derivatives synthesized were characterized by their melting points, optical rotations and partition coefficients. It was found that the Ara-C derivatives synthesized in this study were more lipophilic than Ara-C as determined by their partition coefficients. Their in vitro cytotoxicity and in vivo anti-tumor activity were determined and compared with that of Ara-C. It was found that the derivatives were more active than Ara-C in Hela cells, but not in HL-60 cells. The in vivo results showed that some of the derivatives were more effective than Ara-C in mice bearing S(180) tumor while others showed a decreased activity in comparison with Ara-C.

Novel N-(3-carboxyl-9-benzylcarboline-1-yl)ethylamino acids: synthesis, anti-proliferation activity and two-step-course of intercalation with calf thymus DNA

To explore the intercalating mechanism of -carbolines, four novel N-(3-carboxyl-9-benzyl-carboline-1-yl)ethylamino acids [-phenylalanine (6a), -alanine (6b), -isoleucine (6c) and -glycine (6d)] were prepared here. Their in vitro anticancer activities were examined by their anti-proliferation for 5 human carcinoma cell lines. The average IC50s against 5 human carcinoma cell lines are 53.54 microM, 118.77 microM, 147.34 microM and greater than 291.63 microM for 6a, 6b, 6c and 6d, respectively. The DNA intercalating mechanism of 6a-d was approved by the comparison of the parameters and signals of UV, CD and fluorescence spectra of calf thymus DNA (CT DNA) alone and the CT DNA/6a-d system. Using fluorescence titration based kinetic analysis a two-step-course consisting of stacking and intercalating was described and the stacking was considered as the key step to the CT DNA intercalating mechanism of 6a-d. Using fluorescence titration based thermomechanical analysis, the stacking complexes of 6a-d with CT DNA were described to be formed spontaneously and to be stabilized predominantly by their hydrophobic interactions. The intercalation itself goes very fast and only has limited contribution to their anticancer activities.

Enhanced anticancer activity of glutamate prodrugs of all‐trans retinoic acid

Objectives All‐trans retinoic acid (ATRA), an active metabolite of vitamin A, is widely used in the treatment of acute promyelocytic leukaemia and myelodysplastic syndrome. However, its high lipophilicity is thought to be responsible for the slow dissolution and low bioavailability following oral administration. In order to obtain compounds with better solubility characteristics to improve the transportation and bioavailability of ATRA, derivatives of ATRA containing glutamic acid or its sodium salt were synthesised.

RGD-peptides modifying dexamethasone: to enhance the anti-inflammatory efficacy and limit the risk of osteoporosis

Dexamethasone (Dex) is one of the most effective anti-inflammatory glucocorticoids, while the side effect, osteoporosis seriously limits its clinical use. Cell adhesion is involved in the onset of inflammation and osteoporosis, and RGD-peptides are well known as anti-adhesion peptides. To enhance the anti-inflammatory efficacy and limit the osteoporotic risk of Dex three novel conjugates of RGDV, RGDS and RGDF covalently modified Dex are presented here. For the xylene-induced ear edema model the ear edema of the mice treated with the conjugates was significantly lower than that of the mice treated with Dex. Receiving 15 day therapy the total volumetric bonemineral density, the peripheral quantitative CT and the femur weight of the mice treated with the conjugates were significantly higher than those of the mice treated with Dex. Therefore covalently modifying Dex with RGDV, RGDS and RGDF not only increased the anti-inflammatory activity but also decreased the osteoporotic risk of Dex. In addition, the enhanced anti-inflammatory activity was correlated with the down-regulated DNA expression of the conjugates.

Loading cisplatin onto 6-mercaptopurine covalently modified MSNS: a nanomedicine strategy to improve the outcome of cisplatin therapy

In the treatment of cancer patients, cisplatin (CDDP) exhibits serious cardiac and renal toxicities, while classical combinations related to CDDP are unable to solve these problems and may result in worse prognosis. Alternately, this study covalently conjugated 6-mercaptopurine (6MP) onto the surface of mercapto-modified mesoporous silica nanoparticles (MSNS) to form MSNS-6MP and loaded CDDP into the holes on the surface of MSNS-6MP to form MSNS-6MP/CDDP, a tumor-targeting nano-releasing regime for CDDP and 6MP specifically. In the S180 mouse model, the anti-tumor activity and overall survival of MSNS-6MP/CDDP (50 mg·kg−1·day−1, corresponding to 1 mg·kg−1·day−1 of 6MP and 5 mg·kg−1·day−1 of CDDP) were significantly higher than those of CDDP alone (5 mg·kg−1·day−1) or CDDP (5 mg·kg−1·day−1) plus 6MP (1 mg·kg−1·day−1). The assays of serum alanine aminotransferase, aspartate aminotransferase and creatinine, as well as the images of myocardium and kidney histology, support that MSNS-6MP/CDDP is able to completely eliminate liver, kidney and heart toxicities induced by CDDP alone or CDDP plus 6MP.

RGDS covalently surfaced nanodiamond as a tumor targeting carrier of VEGF-siRNA: synthesis, characterization and bioassay

A nonviral tumor targeting vector for siRNA transfer is of importance. Here, a novel delivery system consisting of a covalent conjugate of NDCO-RGDS and VEGF-siRNA, NDCO-RGDS/VEGF-siRNA, was presented. In vitro, NDCO-RGDS/VEGF-siRNA released and transferred VEGF-siRNA in a long-acting manner. Compared to the control, NDCO-RGDS/VEGF-siRNA decreased the expression of VEGF mRNA and protein in HeLa cells by 88.41 ± 3.49% and 83.94 ± 2.00%, respectively. In vivo, NDCO-RGDS/VEGF-siRNA exhibited gene silencing and slowed tumor growth. FT-MS spectrum analysis revealed that NDCO-RGDS/VEGF-siRNA mainly distributed in tumor tissue of the treated S180 mice. Therefore NDCO-RGDS could be considered a promising nonviral tumor-targeting vector for siRNA transfer in tumor therapy.

Nanomedical strategy to prolong survival period, heighten cure rate, and lower systemic toxicity of S180 mice treated with MTX/MIT

In spite of the usual combination form of methotrexate (MTX)/mitoxantrone (MIT) and various complex combination regimens of MTX/MIT with other anticancer drugs, the survival period, cure rate, and systemic toxicity still need to be improved. For this purpose, a nanostructured amino group-modified mesoporous silica nanoparticles (MSNN)−MTX/MIT was designed. In the preparation, the surface of mesoporous silica nanoparticles (MSNs) was modified with amino groups to form MSNN. The covalent modification of the amino groups on the surface of MSNN with MTX resulted in MSNN−MTX. The loading of MIT into the surface pores of MSNN−MTX produced nanostructured MSNN−MTX/MIT. Compared with the usual combination form (MTX/MIT), nanostructured MSNN−MTX/MIT increased the survival period greatly, heightened the cure rate to a great extent, and lowered the systemic toxicity of the treated S180 mice, significantly. These superior in vivo properties of nanostructured MSNN−MTX/MIT over the usual combination form (MTX/MIT) were correlated with the former selectively releasing MTX and MIT in tumor tissue and inside cancer cells in vitro. The chemical structure and the nanostructure of MSNN−MTX/MIT were characterized using infrared and differential scanning calorimeter spectra as well as transmission electron microscope images, respectively.

Preparation and biological evaluation of tumor-specific Ara-C liposomal preparations containing RGDV motif

Arginine-glycine-aspartate (RGD) has been shown to be essential for the recognition of integrins overexpressed in tumor cells, especially during tumor invasion, angiogenesis, and metasis. In this study, a novel tetrapeptide, RGD-valine (RGDV), was designed and attached to the N position of 1-β-D-arabinofuranosylcytosine (Ara-C) at the valine end, as a homing device for the delivery of Ara-C to tumor cells. Furthermore, fatty acids of various chain lengths (C(n)H(2n+1)COOH, n = 7, 9, 11, 13, and 15) were attached to the arginine end of RGDV to form a series of C(n)H(2n+1)CO-RGDV-Ara-C compounds. The structures of C(n)H(2n+1)CO-RGDV-Ara-C compounds were confirmed using mass spectrometry and nuclear magnetic resonance. The liposomal preparations of the synthesized C(n)H(2n+1)CO-RGDV-Ara-C compounds were obtained using the film dispersion method in the presence of phospholipids. The particle size, zeta potential, and dispersity index of the liposomes formed were found to be approximately 215 nm (diameter), approximately -30 mV, and <0.3, respectively. The antitumor activity of the liposomal preparations containing the respective C(n)H(2n+1)CO-RGDV-Ara-C compounds was evaluated in mice inoculated with sarcoma S(180). Liposomal Ara-C preparation, liposomal C(11)H(23)CO-V-Ara-C preparation, Ara-C, and C(11)H(23)CO-V-Ara-C sodium carboxymethyl cellulose (CMC-Na) suspensions were used as controls. C(n)H(2n+1)CO-RGDV-Ara-C containing liposomal preparations were shown with an enhanced antitumor activity, likely because of the targeting effect of RGDV.

Exploring the Relationship between the Inhibition Selectivity and the Apoptosis of Roscovitine-Treated Cancer Cells

The antitumor activity of roscovitine was tested in four cervical carcinoma cells: C33A, HCE-1, HeLa, and SiHa. The effects of roscovitine on ATP Lite assay, cell cycle, and apoptosis were assessed. The Sub-G1 DNA content occurred great increasing, and this indicates that apoptosis was induced quickly in HeLa cells, but slowly in the other cells. The morphological observation results showed that roscovitine induced apoptosis and cell death in the cervical carcinoma cells. Results revealed that roscovitine exhibited selective cytotoxicity towards 4 cervical carcinoma cells, and the cells showed different morphologic and apoptotic changes at the same concentration. It was estimated that cervical carcinoma cells responded differently to roscovitine because of differences in apoptotic and genetic background in different cervical carcinoma cells. This study suggested that roscovitine had the potential to be a chemotherapeutic agent against cervical carcinoma.