Synthesis and biological evaluation of 173-dicarboxylethyl-pyropheophorbide-a amide derivatives for photodynamic therapy.

Three novel 173-dicarboxylethyl-pyropheophorbide-a amide derivatives as photosensitizers for photodynamic therapy (PDT) were synthesized from pyropheophorbide-a (Ppa). Their photophysical and photochemical properties, intracellular localization, photocytotoxicity in vitro and in vivo were investigated. All target compounds exhibited low cytotoxicity in the dark and remarkable photocytotoxicity against human esophageal cancer cells. Among them, 1a showed highest singlet oxygen quantum yield. Upon light activation, 1a exhibited significant photocytotoxicity. After PDT treatment, the growth of Eca-109 tumor in nude mice was significantly inhibited. Therefore, 1a is a powerful and promising antitumor photosensitizer for PDT.

Synthesis and evaluation of new 5-aminolevulinic acid derivatives as prodrugs of protoporphyrin for photodynamic therapy.

Protoporphyrin IX (PpIX) is used as a photosensitizer in the photodynamic diagnosis (PDD) and photodynamic therapy (PDT) of cancer and is synthesized intracellularly from 5-aminolevulinic acid (5-ALA) precursors. Thirteen novel 5-ALA derivatives were designed and synthesized appropriately with tailored hydrophilicity and lipophilicity. The generation of PpIX was detected and their antitumor activity in vitro and in vivo was also investigated. It was shown that compounds 9b-c, 11b-c and 13a displayed a characteristic long wavelength absorption peak at 593 nm after 5 h incubation in mice fibrosarcoma S180 cells. After being exposed to 600 nm laser light irradiation, these compounds can inhibit cell proliferation in S180 cells in vitro. The growth of S180 cell tumors in Kunming mice was significantly inhibited by these compounds in vivo. Among these compounds, 13a has low dark toxicity and high phototoxicity, which makes it an effective and promising prodrug for PDT.

Antitumor activity of photodynamic therapy with a chlorin derivative in vitro and in vivo.

Chlorin derivatives are promising photosensitive agents for photodynamic therapy (PDT) of tumors. The aim of the current study is to investigate the PDT therapeutic effects of a novel chlorin-based photosensitizer, meso-tetra[3-(N,N-diethyl)aminomethyl-4-methoxy]phenyl chlorin (TMPC) for gliomas in vitro and in vivo. Physicochemical characteristics of TMPC were recorded by ultraviolet visible spectrophotometer and fluorescence spectrometer. The rate of singlet oxygen generation of TMPC upon photo-excitation was detected by using 1,3-diphenylisobenzofuran (DPBF). The accumulation of TMPC in gliomas U87 MG cells was measured by fluorescence spectrometer. The efficiency of TMPC-PDT in vitro was analyzed by MTT assay and clonogenic assay. The biodistribution and clearance of TMPC were determined by fluorescence measuring. Human gliomas U87 MG tumor-bearing mice model was used to evaluate the antitumor effects of TMPC-PDT. TMPC shows a singlet oxygen generation rate of 0.05 and displays a characteristic long wavelength absorption peak at 653 nm (ε = 15,400). The accumulation of TMPC increased with the increase of incubation time. In vitro, PDT using TMPC and laser showed laser dose- and concentration-dependent cytotoxicity to U87 MG cells. In U87 MG tumor-bearing mice, TMPC-PDT significantly reduced the growth of the tumors. Both in vitro and in vivo, TMPC showed little dark toxicity. In vitro and in vivo studies, it found that TMPC has excellent antitumor activities. It suggests that TMPC is a potential photosensitizer of photodynamic therapy for cancer.

The association between Salt-inducible kinase 2 (SIK2) and gamma isoform of the regulatory subunit B55 of PP2A (B55gamma) contributes to the survival of glioma cells under glucose depletion through inhibiting the phosphorylation of S6K.

BACKGROUND: PPP2R2C encodes a gamma isoform of the regulatory subunit B55 subfamily consisting PP2A heterotrimeric with A and C subunits. Currently, the precise functions of B55gamma in cancer are still under investigating. In this project, we reported a novel function of B55gamma in the regulation of glucose metabolism in Glioma cells. METHODS: Western blot and immunoprecipitation were performed to determine protein expression and interaction. Cell viability was measured by Typan Blue staining and direct cell counting using hematocytometer. siRNA technology was used to down regulate protein expression. RESULTS: Glucose uptake and lactate product were suppressed by overexpression of B55gamma in Glioma cells. In addition, cancer cells with larger amount of B55gamma showed higher survival advantages in response to glucose starvation through the dephosphorylation of S6K. From proteomic analysis, we found B55gamma binds with and up regulates SIK2 through the stabilization of SIK2 protein which is required for the B55gamma-mediated suppression of S6K pathway. Knocking down of SIK2 in B55gamma over expressing cells recovered the phosphorylation of S6K. CONCLUSION: In summary, our project will provide novel insight into the design and development of therapeutic strategies to target the B55gamma-mediated glucose metabolism for the treatment of human brain tumor patients.

Decreased miR-106a inhibits glioma cell glucose uptake and proliferation by targeting SLC2A3 in GBM.

BACKGROUND: MiR-106a is frequently down-regulated in various types of human cancer. However the underlying mechanism of miR-106a involved in glioma remains elusive. METHODS: The association of miR-106a with glioma grade and patient survival was analyzed. The biological function and target of miR-106a were determined by bioinformatic analysis and cell experiments (Western blot, luciferase reporter, cell cycle, ntracellular ATP production and glucose uptake assay). Finally, rescue expression of its target SLC2A3 was used to test the role of SLC2A3 in miR-106a-mediated cell glycolysis and proliferation. RESULTS: Here we showed that miR-106a was a tumor suppressor miRNA was involved in GBM cell glucose uptake and proliferation. Decreased miR-106a in GBM tissues and conferred a poor survival of GBM patients. SLC2A3 was identified as a core target of miR-106a in GBM cells. Inhibition of SLC2A3 by miR-106a attenuated cell proliferation and inhibited glucose uptake. In addition, for each biological process we identified ontology-associated transcripts that significantly correlated with SLC2A3 expression. Finally, the expression of SLC2A3 largely abrogated miR-106a-mediated cell proliferation and glucose uptake in GBM cells. CONCLUSIONS: Taken together, miR-106a and SLC2A3 could be potential therapeutic approaches for GBM.

γ-secretase inhibitor up-regulates vascular endothelial growth factor receptor-2 and endothelial nitric oxide synthase.

Although previous studies have shown that γ-secretase inhibitors significantly suppress tumor growth via anti-angiogenesis, the mechanism involved in the regulation of tumor angiogenesis by γ-secretase inhibitors has not been clearly understood. The objective of this study was to investigate the regulation of vascular endothelial growth factor receptor (VEGFR) and endothelial nitric oxide synthase (eNOS) by a γ-secretase inhibitor in the H5V mouse microvascular endothelial cell line. H5V cells were cultured with different concentrations of the γ-secretase inhibitor DAPT for 48 h and with 100 µmol/l DAPT at different incubation times. Protein and mRNA expression of VEGFR-1, VEGFR-2, VEGFR-3 and eNOS was measured by Western blotting and real-time PCR, respectively. The VEGFR-2 kinase inhibitor was used to assess the role of VEGFR-2 in eNOS regulation. We found that the γ-secretase inhibitor DAPT increased protein and mRNA expression of VEGFR-2 and eNOS, but decreased VEGFR-1 expression and had no significant effect on VEGFR-3. Up-regulation of eNOS was blocked by the VEGFR-2 kinase inhibitor. In conclusion, the γ-secretase inhibitor enhances VEGFR-2 and eNOS expression, and the up-regulation of eNOS is dependent on an increase in VEGFR-2. Thus, we suggest that administration of the γ-secretase inhibitor be combined with disruption of eNOS or interruption of VEGF signaling, which may improve the anti-angiogenic efficacy in tumor treatments.