Alpha-tocopheryl succinate enhances doxorubicin-induced apoptosis in human gastric cancer cells via promotion of doxorubicin influx and suppression of doxorubicin efflux

The synergistic antitumor effects of all-trans retinoic acid and C-phycocyanin on the lung cancer A549 cells in vitro and in vivo

The anticancer effects and mechanism of all-trans retinoic acid (ATRA), C-phycocyanin (C-PC) or ATRA+C-PC on the growth of A549 cells were studied in in vitro and in vivo experiments. The effects of C-PC and ATRA on the growth of A549 cells were determined. The expression of CDK-4 and caspase-3, and the cellular apoptosis levels were detected. The tumor model was established by subcutaneous injection of A549 cells to the left axilla of the NU/NU mice. The weights of tumor and the spleen were tested. The viabilities of T-cells and spleen cells, TNF levels, the expression of Bcl-2 protein and Cyclin D1 gene were examined. Results showed both C-PC and ATRA could inhibit the growth of tumor cells in vivo and in vitro. ATRA+C-PC cooperatively showed a higher antitumor activity. The dosage of ATRA was reduced when it was administered with C-PC together, and the toxicity was reduced as well. ATRA+C-PC could decrease CDK-4 but increase caspase-3 protein expression level and induce cell apoptosis. ATRA alone could lower the activities of T lymphocytes and spleen weights, but the combination with C-PC could effectively promote viability of T cells and spleen. C-PC+ATRA could up-regulate TNF, and down-regulate Bcl-2 and Cyclin D1 gene. The combination might inhibit tumor growth by inhibiting the progress of cell cycle, inducing cell apoptosis and enhancing the body immunity.

Preparation and characterization of potential doxorubicin-loaded mixed micelles formed from vitamin E containing graft copolymers and PEG-b-PLA diblock copolymers

Mixed micelles formed from mPEG-b-PLA and PHPMA-g-α-TOS were investigated to accelerate drug release, improve cancer cell uptake and enhance cytotoxicity.

Co-delivery of paclitaxel and α-tocopherol succinate by novel chitosan-based polymeric micelles for improving micellar stability and efficacious combination therapy

The aim of this study was to develop chitosan derivative polymeric micelles for co-delivery of paclitaxel (PTX) and α-tocopherol succinate (α-TS) to the cancer cells to improve the therapeutic efficiency and reduce side effects of PTX. In this study, amphiphilic tocopheryl succinate-grafted chitosan oligosaccharide was synthesized and physically loaded by PTX and α-TS with entrapment efficiency of 67.9% and 73.2%, respectively. Physical incorporation of α-TS into the micelles increased the hydrophobic interaction between PTX and the micelles core, which improved micelle stability, reduced the micelle size and also sustained the PTX release from the micelles. The mean particle size and zeta potential of αTS/PTX-loaded micelles were about 133 nm and +25.2 mV, respectively, and PTX release was completed during 6-9 d from the micelles. Furthermore, the cytotoxicity of α-TS/PTX-loaded micelles against human ovarian cancer cell line cancer cell in vitro was higher than that of PTX-loaded micelles and the free drug solution. Half maximal inhibitory concentration values of PTX after 48-h exposure of the cells to the PTX-loaded micelles modified and unmodified with α-TS were 110 and 188 ng/ml, respectively.

RRR-α-tocopheryl succinate induces apoptosis in human gastric cancer cells via the NF-κB signaling pathway

To investigate the effects of the nuclear factor (NF)-κB signaling pathway on the induction of apoptosis by vitamin E succinate (RRR-α-tocopheryl succinate; VES) in human gastric carcinoma cells. Human gastric carcinoma SGC-7901 cells were treated with temperate concentrations of VES and pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF-κB. Cell viability and apoptosis were respectively estimated by methylthiazol tetrazolium (MTT) assay and the Annexin V‑FITC method. Western blot analysis was used to evaluate the protein expressions of NF-κBp65 and Bcl-2 family members Bcl-2, Bax and cleavage of caspase-3, caspase-9, and poly (ADP-ribose) polymerase (PARP). The DNA-binding activity of NF-κBp65 was measured by electrophoretic mobility shift assay (EMSA). Reverse transcription and polymerase chain reaction (RT-PCR) was implemented to evaluate the transcription of inhibitor of apoptosis (IAP) genes. Apoptosis assessment showed that VES induces apoptotic cell death in human gastric carcinoma cells. In the following experiments, PDTC (100 µM) was used in cell treatment 2 h before VES. The decreased ratio of the nuclear and cytosolic NF-κBp65 protein level was induced by VES and PDTC reinforced this trend. PDTC treatment significantly enhanced the decrease of NF-κB-DNA binding activity induced by VES in human gastric SGC-7901. The decrease in protein expression of Bcl-2 as well as the increase in the protein expression of Bax were induced by VES treatment. The cleavage of caspase-9, caspase-3 and PARP was induced. There was no effect on the gene transcription of c-IAP-1, c-IAP-2, and x-linked IAP (XIAP) compared with the control group, whereas mRNA levels of survivin and the neuronal apoptosis inhibitory protein (NAIP) markedly decreased. Notably, pretreatment with PDTC reinforced all the above VES-induced effects. In conclusion, VES-induced apoptosis in SGC-7901 cells is accompanied by the inhibition of the NF-κB signaling pathway, including changes in Bcl-2 family members, cleavage of caspases and gene transcription of survivin and NAIP.

Molecular mechanism of inhibitory effects of C-phycocyanin combined with all-trans-retinoic acid on the growth of HeLa cells in vitro

We studied the effects of all-trans-retinoic acid (ATRA), C-phycocyanin (C-PC), or ATRA+C-PC on the growth of cervical cells (HeLa cells), cell cycle distribution, and apoptosis. The anticancer mechanism of the drug combination was revealed. MTT assay was adopted to determine the effects of C-PC and ATRA on the growth of HeLa cells. The expression quantities of cyclin-dependent kinase (CDK) 4, cyclin D1, Bcl-2, caspase-3, and CD59 were determined by in situ hybridization, immunofluorescence, immunohistochemistry staining, Western blot, and RT-PCR. TUNEL assay was adopted to determine the cellular apoptosis levels. Both C-PC and ATRA could inhibit the growth of HeLa cells, and the combination of ATRA+C-PC functioned cooperatively to induce apoptosis in HeLa cells. The dosage of ATRA was reduced when it cooperated with C-PC to reduce the toxicity. ATRA treated with C-PC could induce more cell cycle arrests than the single drug used by decrease in cyclin D1 and CDK4 expression. The combination of the two drugs could upregulate caspase-3 and downregulate the Bcl-2 gene and induce cell apoptosis. Moreover, the combination therapy has an important immunological significance in decreased expression of the CD59 protein. Singly, C-PC or ATRA could inhibit the growth of HeLa cells, and the effects of treatment were further enhanced in the combination group. In combination with C-PC, the dosage of ATRA was effectively reduced. The C-PC + ATRA combination might take effect by inhibiting the progress of the cell cycle, inducing cell apoptosis and promoting complement-mediated cytolysis.

Self-assembling doxorubicin-tocopherol succinate prodrug as a new drug delivery system: synthesis, characterization, and in vitro and in vivo anticancer activity

Self-assembled prodrugs forming nanoaggregates are a promising approach to enhance the antitumor efficacy and to reduce the toxicity of anticancer drugs. To achieve this goal, doxorubicin was chemically conjugated to d-α-tocopherol succinate through an amide bond to form N-doxorubicin-α-d-tocopherol succinate (N-DOX-TOS). The prodrug self-assembled in water into 250 nm nanostructures when stabilized with d-α-tocopherol poly(ethylene glycol) 2000 succinate. Cryo-TEM analysis revealed the formation of nanoparticles with a highly ordered lamellar inner structure. NMR spectra of the N-DOX-TOS nanoparticles indicated that N-DOX-TOS is located in the core of the nanoparticles while PEG chains and part of the tocopherol are in the corona. High drug loading (34% w/w) and low in vitro drug release were achieved. In vitro biological assessment showed significant anticancer activity and temperature-dependent cellular uptake of N-DOX-TOS nanoparticles. In vivo, these nanoparticles showed a greater antitumor efficacy than free DOX. N-DOX-TOS nanoparticles might have the potential to improve DOX-based chemotherapy.

Alteration of α-tocopherol-associated protein (TAP) expression in human breast epithelial cells during breast cancer development

Breast cancer is the most common malignancy among women and has an age-specific incidence profile. Over the last decade, many studies have demonstrated the anticancer activity of α-tocopherol, the main and most active form of natural vitamin E. α-Tocopherol-associated protein (TAP) was found to be one of the major α-tocopherol binding proteins in human serum and in liver, brain, and prostate tissues. In this study, we found that reduced TAP expression was significantly correlated with Her2/neu receptor expression, breast cancer stage and nodal stage in paired normal and cancerous breast tissue samples from 93 patients using real-time PCR analysis. A cell viability assay showed that α-tocopheryl succinate (α-TOS), a synthetic derivative of α-tocopherol, enhanced the cells' sensitivity to doxorubicin and resulted in a reduction in cell viability in breast cancers. Taken together, these data suggest that the use of vitamin E or its analogue as a dietary supplement may be beneficial for the treatment of cancer.