Effect of photofrin II and light energy on retinoblastoma-like cells in vitro

Several clinical studies, as well as investigations performed on tissue cultures and murine tumor models, have demonstrated the in vitro and in vivo efficacy of Photofrin II and hypericin as radiosensitizing agents. The mechanisms involved in the radiosensitizing action of Photofrin II and hypericin are partially understood; the recognition of the major role performed by oxygen regarding the modulation of cellular radiosensitivity has prompted the present investigations on the relevance of oxygenation for the success of Photofrin II or hypericin-based radiation therapy of tumors. RT4 human bladder carcinoma cell lines were seeded and incubated with various concentrations of Photofrin II or hypericin under ambient and 5% oxygen levels. The cells were irradiated with ionizing radiation between 1 and 6 Gy. The same experiments were repeated with Photofrin II and hypericin alone, without radiation. The cell survival was evaluated. The results demonstrated an increase of radiation-induced cell damage in the presence of Photofrin II and hypericin, respectively, when sufficient oxygen was available. Low levels of oxygen reduced the activity of Photofrin II as well as of hypericin as a radiosensitizer, with minimal tumor damage ( p < 0.05 in a Student t-test). The mechanism of action of Photofrin II and hypericin as radiosensitizers requires the presence of sufficiently high oxygen concentrations.

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In Vitro Photodynamic Treatment of Normal and Human Papilloma Virus-Transfected Keratinocytes With Photofrin II and Red Light

Archives of Dermatology ◽

10.1001/archderm.1991.01680040091009 ◽

1991 ◽

Vol 127 (5) ◽

pp. 683

Author(s):

Eric F. Bernstein

Keyword(s):

Human Papilloma Virus ◽

Red Light ◽

Photodynamic Treatment ◽

Papilloma Virus ◽

Photofrin Ii

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Photosensitization by the Near-IR-absorbing Photosensitizer Lutetium Texaphyrin: Spectroscopic, In Vitro and In Vivo Studies

Journal of Porphyrins and Phthalocyanines ◽

10.1002/(sici)1099-1409(199807/10)2:4/5<383::aid-jpp94>3.0.co;2-y ◽

1998 ◽

Vol 02 (05) ◽

pp. 383-390 ◽

Cited By ~ 15

Author(s):

GENADY KOSTENICH ◽

TANYA BABUSHKINA ◽

ADINA LAVI ◽

YAKOV LANGZAM ◽

ZVI MALIK ◽

...

Keyword(s):

Cell Membrane ◽

Structural Damage ◽

Biological Properties ◽

In Vivo Studies ◽

Outer Cell ◽

Lipid Bilayer Membranes ◽

Photofrin Ii ◽

Ionic Imbalance

The spectroscopic and biological properties of the new photosensitizer lutetium texaphyrin (Lu-Tex) were assessed in vitro and in vivo on a C26 colon carcinoma model, in comparison with hematoporphyrin (Hp), photofrin II (PII) and chlorin e 6( Chl ). Strong binding of Lu-Tex to lipid bilayer membranes was observed. The results of confocal fluorescence microscopy on C26 cells showed that Lu-Tex was localized in small vesicles in the cytoplasm, possibly in the lysosomes, while Chl and Hp were distributed in larger cytoplasmic vesicles attributed to mitochondria. Scanning electron microscopy and X-ray microanalysis revealed that photodynamic therapy with Lu-Tex induced only slight damage to the cell membrane, leading to a delayed cell response. Chl and Hp caused significant structural damage to the outer cell membrane, resulting in ionic imbalance and fast cell death. The in vitro quantitative assessment of the relative efficiency per absorbed photon of the sensitizers revealed that Lu-Tex was less effective than Chl and Hp . However, the results of our in vivo study showed that at the same light and drug doses the anti-tumor efficiency of the agents was in the following order: Lu-Tex > Chl > PII . The strong in vivo anti-tumor effect of Lu-Tex can be explained by its higher integrated absorption in the long-wavelength range.

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