Mechanistic study of PpIX accumulation using the JFCR39 cell panel revealed a role for dynamin 2-mediated exocytosis

Yuya Kitajima,Masahiro Ishizuka,Kanami Yamazaki,Takeo Kohda,Takuya Ishii,Yumiko Nishimura,Shingo Dan,Motowo Nakajima,Tohru Tanaka

doi:10.1038/s41598-019-44981-y

Yuya Kitajima, Masahiro Ishizuka + Show 7 more

Open Access

https://doi.org/10.1038/s41598-019-44981-y

Copy DOI

Abstract

5-aminolevulinic acid (5-ALA) has recently been employed for photodynamic diagnosis (ALA-PDD) and photodynamic therapy (ALA-PDT) of various types of cancer because hyperproliferating tumor cells do not utilize oxidative phosphorylation and do not efficiently produce heme; instead, they accumulate protoporphyrin IX (PpIX), which is a precursor of heme that is activated by violet light irradiation that results in the production of red fluorescence and singlet oxygen. The efficiencies of ALA-PDD and ALA-PDT depend on the efficient cellular uptake of 5-ALA and the inefficient excretion of PpIX. We employed the JFCR39 cell panel to determine whether tumor cells originating from different tissues can produce and accumulate PpIX. We also investigated cellular factors/molecules involved in PpIX excretion by tumor cells with the JFCR39 cell panel. Unexpectedly, the expression levels of ABCG2, which has been considered to play a major role in PpIX extracellular transport, did not show a strong correlation with PpIX excretion levels in the JFCR39 cell panel, although an ABCG2 inhibitor significantly increased intracellular PpIX accumulation in several tumor cell lines. In contrast, the expression levels of dynamin 2, which is a cell membrane-associated molecule involved in exocytosis, were correlated with the PpIX excretion levels. Moreover, inhibitors of dynamin significantly suppressed PpIX excretion and increased the intracellular levels of PpIX. This is the first report demonstrating the causal relationship between dynamin 2 expression and PpIX excretion in tumor cells.

Highlights

Diagnostic imaging techniques for cancer, such as computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET), have been widely adopted, and their effectiveness has been confirmed
We evaluated cancer detection via 5-aminolevulinic acid (5-ALA)-derived protoporphyrin IX (PpIX) accumulation using cancer cells originating from various tissues under the same conditions
We employed the JFCR39 cell panel, which is a well-characterized panel of human cancer cell lines, as a model system

Summary

Introduction

Diagnostic imaging techniques for cancer, such as computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET), have been widely adopted, and their effectiveness has been confirmed. In contrast to normal differentiated cells, which primarily rely on mitochondrial oxidative phosphorylation to generate the energy needed for cellular processes, most cancer cells instead rely on aerobic glycolysis, which consumes a large amount of glucose and produces excess lactate, resulting in acidosis This phenomenon is termed “the Warburg effect” and causes a lack of NADH and the insufficient conversion of Fe3+ to Fe2+, resulting in low FECH activity and the consequent accumulation of PpIX, especially when an abundant amount of 5-ALA is exogenously administered[23]. Hagiya et al.[39] reported that the balance between the protein expression level of PEPT1, which is a peptide transporter that is involved in the uptake of ALA into cells, and the expression level of ATP binding cassette subfamily G member 2 (ABCG2), which is a drug-resistant transporter involved in the elimination of PpIX, was correlated with the levels of PpIX accumulation in several gastric cancer cell lines They showed that ABCG2 inhibitors suppress the extracellular excretion of PpIX and increase its intracellular accumulation

Methods

Results

Conclusion