Abstract | BACKGROUND:
Glioblastoma (GBM) is a highly malignant lethal brain cancer. Accumulated evidence suggests that elevated resistance of GBM to both chemo- and radio- therapy is, at least in part, due to the presence of a small population of glioma stem cells (GSC). In the present study, we aimed to determine the sensitivity of GSCs to 5-aminolevulinic acid-mediated photodynamic therapy (ALA- PDT). METHODS: For this purpose, we established GSC-enriched cell cultures (termed glioma stem-like cells or GSLCs) from A172 human GBM cell line. Under our cultivation conditions, GSLCs formed floating spheroid clusters that contained increased population of CD133/Sox2 expressing cells. Firstly, to compare the activity of protoporphyrin IX ( PpIX) biosynthesis in the GSLCs and the parental A172 glioma cells, we examined the expression levels of biosynthesis enzymes and transporters for PpIX using qRT-PCR, and investigated the intracellular levels of PpIX with use of flow cytometry analysis. Then, we evaluated the sensitivity of these cells to ALA- PDT in vitro. Finally, to confirm the therapeutic impact of ALA- PDT on GSLCs with more clinically relevant model, we performed the same experiment using three different patient-derived glioma sphere lines, which cultivated them either in stem cell media or under differentiation conditions in the presence of serum. RESULTS AND CONCLUSION: GSLCs expressed higher mRNA levels of PpIX biosynthesis enzymes and its transporters PEPT1/2 and ABCB6, when compared to the parental A172 glioma cells. Consistently, flow cytometry analysis revealed that upon incubation with ALA, GSLCs accumulate a higher level of PpIX. Finally, we showed that GSLCs were more sensitive to ALA- PDT than the original A172 cells, and confirmed that all patient-derived glioma sphere lines also showed significantly increased sensitivity to ALA- PDT if cultivated under the pro-stem cell condition. Our data indicate that ALA- PDT has potential as a novel clinically useful treatment that might eliminate GBM stem cells that are highly resistant to current chemo- and radio- therapy.
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Authors | Takahiro Fujishiro, Naosuke Nonoguchi, Marat Pavliukov, Naoki Ohmura, Shinji Kawabata, Yangtae Park, Yoshinaga Kajimoto, Toshihisa Ishikawa, Ichiro Nakano, Toshihiko Kuroiwa |
Journal | Photodiagnosis and photodynamic therapy
(Photodiagnosis Photodyn Ther)
Vol. 24
Pg. 58-68
(Dec 2018)
ISSN: 1873-1597 [Electronic] Netherlands |
PMID | 29990642
(Publication Type: Journal Article)
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Copyright | Copyright © 2018 Elsevier B.V. All rights reserved. |
Chemical References |
- AC133 Antigen
- Photosensitizing Agents
- Protoporphyrins
- RNA, Messenger
- SOX Transcription Factors
- SOX15 protein, human
- Aminolevulinic Acid
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Topics |
- AC133 Antigen
(biosynthesis)
- Aminolevulinic Acid
(pharmacology)
- Brain Neoplasms
(drug therapy)
- Cell Line, Tumor
- Drug Resistance, Neoplasm
- Glioblastoma
(drug therapy, pathology)
- Humans
- Neoplastic Stem Cells
(drug effects)
- Photochemotherapy
(methods)
- Photosensitizing Agents
(pharmacology)
- Protoporphyrins
(biosynthesis)
- RNA, Messenger
- SOX Transcription Factors
(biosynthesis)
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