Silencing of ferrochelatase enhances 5-aminolevulinic acid-based fluorescence and photodynamic therapy efficacy.

BACKGROUND: Recurrence of glioma frequently occurs within the marginal area of the surgical cavity due to invading residual cells. 5-Aminolevulinic acid (5-ALA) fluorescence-guided resection has been used as effective therapeutic modalities to improve discrimination of brain tumour margins and patient prognosis. However, the marginal areas of glioma usually show vague fluorescence, which makes tumour identification difficult, and the applicability of 5-ALA-based photodynamic therapy (PDT) is hampered by insufficient therapeutic efficacy in glioma tissues. METHODS: To overcome these issues, we assessed the expression of ferrochelatase (FECH) gene, which encodes a key enzyme that catalyses the conversion of protoporphyrin IX (PpIX) to heme, in glioma surgical specimens and manipulated FECH in human glioma cell lines. RESULTS: Prominent downregulation of FECH mRNA expression was found in glioblastoma tissues compared with normal brain tissues, suggesting that FECH is responsible for PpIX accumulation in glioblastoma cells. Depletion of FECH by small interference RNA enhanced PpIX fluorescence after exposure to 5-ALA concomitant with increased intracellular PpIX accumulation in glioma cells. Silencing of FECH caused marked growth inhibition and apoptosis induction by PDT in glioma cells. CONCLUSION: These results suggest that knockdown of FECH is a potential approach to enhance PpIX fluorescent quality for optimising the subjective discrimination of vague fluorescence and improving the effect of 5-ALA-PDT.

Bone marrow-derived stromal cells can express neuronal markers by DHA/GPR40 signaling.

The exact origin of neural stem cells in the adult neurogenesis niche remains unknown. Our previous studies, however, indicated an implication of both bone marrow cells as potential progenitors of hippocampal newborn neurons and polyunsaturated fatty acids as ligands of G protein-coupled receptor 40 (GPR40) signaling. Here, we aimed at studying whether bone marrow-derived stromal cells (BMSC) treated by docosahexaenoic acid (DHA) can express neuronal markers in vitro. We focused on implication of DHA/GPR40 signaling for the expression of neural markers in clonally-expanded BMSC from young macaque monkeys. Cell cycle analysis revealed that the DHA plus bFGF treatment induced a decrease of BMSC proliferation and increased the cells in the G0 resting phase. The transitions from nestin-positive progenitors via immature neuronal (beta III-tubulin-positive) to mature neuronal (NF-M and Map2-positive) phenotypes were examined using RT-PCR, Western blot and immunocytochemistry. We detected a significant increase of GPR40 mRNA and protein expression after bFGF induction, being compared with the untreated BMSC. Addition of DHA, a representative GPR40 ligand, led to a significant down-regulation of GPR40, i.e., G protein-coupled receptor-specific internalization, with a subsequent upregulation of neuronal markers such as beta III-tubulin, NF-M and Map2. These data altogether suggest that adult primate BMSC can express neuronal markers with the aid of DHA/GPR40 signaling.