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Laser dyes for experimental phototherapy of human cancer: Comparison of three rhodamines
Author(s) -
Haghighat Shaghayegh,
Castro Dan J.,
Lufkin Robert B.,
Fetterman Harold R.,
Castro Donna J.,
Soudant Jacques,
Ward Paul H.,
Saxton Romaine E.
Publication year - 1992
Publication title -
the laryngoscope
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.181
H-Index - 148
eISSN - 1531-4995
pISSN - 0023-852X
DOI - 10.1288/00005537-199201000-00016
Subject(s) - rhodamine 123 , photosensitizer , in vitro , chemistry , in vivo , dye laser , microbiology and biotechnology , laser , photodynamic therapy , rhodamine 6g , fluorescence , biology , photochemistry , biochemistry , optics , physics , organic chemistry , molecule , multiple drug resistance , antibiotics
The mitochondrial dye Rhodamine 123 (Rh‐123) has been shown to be an effective photosensitizer for argon‐laser irradiation of some types of human cancer cells in vitro. We reported that 514.5‐nm laser illumination of Rh‐123 sensitized human melanoma, and squamous carcinoma cells strongly inhibited tumor‐cell proliferation as measured by decreased 3 H‐thymidine ( 3 H‐T) uptake in vitro and may eradicate some tumors when grown as transplants in nude mice. However, several other human tumors were resistant to Rh‐123 laser therapy in vitro and in vivo. In the current study, it was possible to obtain 100‐ to 1000‐fold increased sensitivity to 514.5‐nm laser illumination by replacement of Rh‐123 with the cationic rhodamine dyes Rh‐3G and Rh‐6G. Cell viability was decreased over 95% and 3 H‐T incorporation reduced at least 80% by laser phototherapy after sensitizing tumor cells with 1 μg/mL Rh‐123, 0.01 μg/mL Rh‐3G, or 0.001 μg/mL Rh‐6G. However, Rh‐123 alone did not decrease 3 H‐T uptake significantly unless present at over 10‐ to 100‐fold higher levels than Rh‐3G, respectively. The tumor cell dye uptake level was measured by N‐butanol extraction and absorption scans at 400 to 600 nm. The results revealed that dye uptake was more rapid, and retention of Rh‐3G and Rh‐6G was 5‐ to 10‐fold higher than for Rh‐123 in the human tumor cells. The data suggest that Rh‐3G and Rh‐6G may be highly sensitive chromophores for laser phototherapy of human cancer cells.