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

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.

Real-time spectrum quantification of tumor-related fluorescence during neurosurgery: A preliminary report.

OBJECTIVES: The fluorescent dye, 5-aminolevulinic acid (5-ALA), is currently applied for fluorescence-guided resections of high-grade gliomas. Present limitations of this technique are qualitative and subjective analyses, which show little of the background structures. This paper describes the intraoperative quantitative analysis of fluorescence intensity, hot-spot enhancement by frame averaging, and observation of surrounding structures by using 1000-nm lighting in real time. PATIENTS AND METHODS: A sample of diluted protoporphyrin IX (PpIX) in a bottle and 37 samples from nine patients with brain lesions were involved in this study. In this preliminary study, we determined appropriate conditions for image averaging and filters and selected the most sensitive spectrometer. In addition, we utilized a 1000-nm lighting system to visualize surrounding structures with no interference from PpIX fluorescence. RESULTS: The novel system permitted the real-time quantitative analysis of PpIX fluorescence in operative fields by illuminating structures with 1000-nm-lighting. The real-time quantification provided subjective evaluations for surgical decision-making. We found good correlations between the fluorescence and PpIX contents in brain tissue. Furthermore, 1000-nm lighting visualized the anatomical structures and PpIX fluorescence simultaneously. CONCLUSION: The combination of spectroscopy and a 1000-nm lighting system could enable surgeons to create a spectrogram of targets of interest while observing background structures. The spectrometer that we selected is highly sensitive to PpIX fluorescence and enables us to perform intraoperative real-time tissue mapping. By using a real-time system, we can perform quantitative and objective evaluations to achieve maximal tumor resection.

Novel potential photodynamic therapy strategy using 5-Aminolevulinic acid for ovarian clear-cell carcinoma.

BACKGROUND: Photodynamic therapy (PDT) is known as a minimally invasive treatment for cancer. 5-Aminolevulinic acid (ALA) is a precursor of the photosensitizing agent protoporphyrin IX (PpIX). Patients with ovarian clear-cell carcinoma (CCC) have poorer prognoses than those of patients with other histological CCC types. We evaluated the efficacy of ALA-PDT on CCC cells in vitro. METHODS: We used seven human CCC cell lines to measure the cytotoxicity of ALA-PDT. PpIX production in cancer cells was measured using a micro-plate reader. Quantitative real-time PCR was performed to assess the mRNA levels of genes involved in the accumulation of PpIX in cancer cells. Additionally, we measured the enhancement in cytotoxicity with the use of an ABCG2 inhibitor. RESULTS: We found that three cell lines were highly sensitive to ALA-PDT. In contrast, one cell line was resistant to ALA-PDT. The cytotoxicity of ALA-PDT varied among CCC cell lines. The IC50 values of ALA-PDT for the CCC cell lines had a wide range (30-882µM). The cytotoxicity of ALA-PDT was correlated with the intracellular PpIX accumulation. The cell lines sensitive to ALA-PDT expressed PEPT1 (an ALA uptake transporter). The cell line resistant to ALA-PDT expressed ABCG2 (a PpIX export transporter). In the resistant cell line, a combination treatment with both ALA and an ABCG2 inhibitor resulted in the promotion of cytotoxic sensitivity. CONCLUSION: The present study revealed the efficacy of ALA-PDT against CCC with chemoresistance in vitro.

5-aminolevulinic acid combined with ferrous ion reduces adiposity and improves glucose tolerance in diet-induced obese mice via enhancing mitochondrial function.

BACKGROUND: Mitochondrial dysfunction is associated with obesity and various obesity-associated pathological conditions including glucose intolerance. 5-Aminolevulinic acid (ALA), a precursor of heme metabolites, is a natural amino acid synthesized in the mitochondria, and various types of cytochromes containing heme contribute to aerobic energy metabolism. Thus, ALA might have beneficial effects on the reduction of adiposity and improvement of glucose tolerance through its promotion of heme synthesis. In the present study, we investigated the effects of ALA combined with sodium ferrous citrate (SFC) on obesity and glucose intolerance in diet-induced obese mice. METHODS: We used 20-weeks-old male C57BL/6J diet-induced obesity (DIO) mice that had been fed high-fat diet from 4th week or wild-type C57BL/6J mice. The DIO mice were orally administered ALA combined with SFC (ALA/SFC) for 6 weeks. At the 4th and 5th week during ALA/SFC administration, mice were fasted for 5 h and overnight, respectively and used for oral glucose tolerance test. After the ALA/SFC administration, the plasma glucose levels, weight of white adipose tissue, and expression levels of mitochondrial oxidative phosphorylation (OXPHOS) complexes were examined. Furthermore, the effects of ALA/SFC on lipid content and glucose uptake were examined in vitro. RESULTS: Oral administration of ALA/SFC for 6 weeks reduced the body weight by about 10% and the weight of white adipose tissues in these animals. In vitro, ALA/SFC reduced lipid content in mouse 3T3-L1 adipocytes in a dose dependent manner, and enhanced glucose uptake in 3T3-L1 adipocytes by 70-90% and rat L6 myoblasts by 30% at 6 h. Additionally, oral administration of ALA/SFC reduced plasma glucose levels and improved glucose tolerance in DIO mice. Furthermore, ALA/SFC enhanced the expression of OXPHOS complexes III, IV, and V by 40-70% in white adipose tissues of DIO mice, improving mitochondrial function. CONCLUSIONS: Our findings indicate that ALA/SFC is effective in the reduction of adiposity and improvement of glucose tolerance, and that the induction of mitochondrial OXPHOS complex III, IV, and V by ALA/SFC might be an essential component of the molecular mechanisms underlying these effects. ALA/SFC might be a useful supplement for obesity and obesity-related metabolic disease such as type 2 diabetes mellitus.

Impaired CD98 signaling protects against graft-versus-host disease by increasing regulatory T cells.

Graft-versus-host disease (GvHD) is a major barrier to the broader use of allogenic hematopoietic stem cell transplantation for non-malignant clinical applications. A murine model of C57BL/6 to B6D2F1 acute GvHD was employed with T lymphocytes harboring a deletion of the CD98 heavy chain (CD98hc(-/-)) as donor cells. The CD98hc(-/-) resulted in lower responses to alloantigen stimulation in a mixed leukocyte reaction assay, and prevented the mortality associated with disease progression. The percentage of donor CD8 T lymphocytes was significantly decreased, while the percentage of Foxp3-positive regulatory T cells (Tregs) in recipients was increased by CD98hc(-/-). Decreased expression of FAS, FASL, ICOS, ICOSL, PD-1 and PD-L1 by donor CD8 T cells, and mRNA expression of cytotoxic T cell-related cytokines in the recipients were shown in those with CD98hc(-/-). Fewer infiltrated cells are found in the lungs, liver, tongue and skin of recipients with CD98hc(-/-) compared with the wild type recipients. Taken together, our data indicate that T cell-specific deletion of CD98hc can contribute to the prevention of GvHD development due to the attenuation of lymphocyte migration and by increasing the generation of Treg cells. These findings are expected to make it possible to develop novel approaches for the prevention of GvHD.

Optical properties of tumor tissues grown on the chorioallantoic membrane of chicken eggs: tumor model to assay of tumor response to photodynamic therapy.

Herein, the optical adequacy of a tumor model prepared with tumor cells grown on the chorioallantoic membrane (CAM) of a chicken egg is evaluated as an alternative to the mouse tumor model to assess the optimal irradiation conditions in photodynamic therapy (PDT). The optical properties of CAM and mouse tumor tissues were measured with a double integrating sphere and the inverse Monte Carlo technique in the 350- to 1000-nm wavelength range. The hemoglobin and water absorption bands observed in the CAM tumor tissue (10 eggs and 10 tumors) are equal to that of the mouse tumor tissue (8 animals and 8 tumors). The optical intersubject variability of the CAM tumor tissues meets or exceeds that of the mouse tumor tissues, and the reduced scattering coefficient spectra of CAM tumor tissues can be equated with those of mouse tumor tissues. These results confirm that the CAM tumor model is a viable alternative to the mouse tumor model, especially for deriving optimal irradiation conditions in PDT.

Generation and characterization of regulatory dendritic cells derived from murine induced pluripotent stem cells.

Regulatory dendritic cells (DCregs) represent a potential therapeutic tool for assessing a variety of immune overreaction conditions; however, current approaches for generating DCregs for therapeutic purposes are limited. We attempted to generate and characterize DCregs from murine induced pluripotent stem (iPS) cells. The iPS cells co-cultured with OP9 cells displayed mesodermally differentiated flat colonies. GM-CSF drove most of the colonies exhibiting a differentiated morphology. Thereafter, cells became morphologically heterologous under the effects of TGF-ß and IL-10. Most of the floating cells developed an irregular shape with areas of protrusion. The generated iPS-DCregs demonstrated high CD11b/c and low CD40, CD80, CD86 and MHC-II expressions with a high antigen uptake ability and poor T-cell stimulatory function. Importantly, iPS-DCregs showed immune responsiveness regulation effects both in vitro and in vivo and the ability to generate regulatory T-cells in vitro. Our result illustrates a feasible approach for generating functional DCregs from murine iPS cells.

5-Aminolevulinic acid combined with ferrous iron induces carbon monoxide generation in mouse kidneys and protects from renal ischemia-reperfusion injury.

Renal ischemia reperfusion injury (IRI) is a major factor responsible for acute renal failure. An intermediate in heme synthesis, 5-aminolevulinic acid (5-ALA) is fundamental in aerobic energy metabolism. Heme oxygenase (HO)-1 cleaves heme to form biliverdin, carbon monoxide (CO), and iron (Fe(2+)), which is used with 5-ALA. In the present study, we investigated the role of 5-ALA in the attenuation of acute renal IRI using a mouse model. Male Balb/c mice received 30 mg/kg 5-ALA with Fe(2+) 48, 24, and 2 h before IRI and were subsequently subjected to bilateral renal pedicle occlusion for 45 min. The endogenous CO concentration of the kidneys from the mice administered 5-ALA/Fe(2+) increased significantly, and the peak concentrations of serum creatinine and blood urea nitrogen decreased. 5-ALA/Fe(2+) treatments significantly decreased the tubular damage and number of apoptotic cells. IRI-induced renal thiobarbituric acid-reactive substance levels were also significantly decreased in the 5-ALA/Fe(2+) group. Furthermore, mRNA expression of HO-1, TNF-α, and interferon-γ was significantly increased after IRI. Levels of HO-1 were increased and levels of TNF-α and interferon-γ were decreased in the 5-ALA/Fe(2+)-pretreated renal parenchyma after IRI. F4/80 staining showed reduced macrophage infiltration, and TUNEL staining revealed that there were fewer interstitial apoptotic cells. These findings suggest that 5-ALA/Fe(2+) can protect the kidneys against IRI by reducing macrophage infiltration and decreasing renal cell apoptosis via the generation of CO.