ABSTRACT
In tissue culture, azelaic acid (C9) has been shown to have an anti-proliferative and cytotoxic effect on human and murine malignant melanocytes, with inhibition of mitochondrial oxido-reductase enzymes and DNA synthesis, and damage to mitochondria. Recent reports of effects on differentiation of normal keratocytes have led to the present study of its effects on a squamous carcinoma cell line. Cells were exposed to single doses of disodium salts of azelaic (C9(2)Na) and adipic (C6(2)Na) acids at concentrations of 10(-2)M and 5 x 10(-2)M for 48 hrs. Only C9(2)Na at 5 x 10(-2) M for 4 hrs., and longer, significantly affected proliferation, and the cells exhibited massive swelling of mitochondria with loss of cristae. The results further confirm the probable value of azelaic acid as a general anti-tumoral agent rather than a specifically melanocytotoxic one. They could justify clinical studies on the effect of topical azelaic acid therapy on squamous cell carcinoma in vivo.
Subject(s)
Carcinoma, Squamous Cell/ultrastructure , Dicarboxylic Acids/pharmacology , Adipates/pharmacology , Antineoplastic Agents/pharmacology , Cell Division/drug effects , Cell Survival/drug effects , Humans , Microscopy, Electron , Mitochondrial Swelling/drug effects , Tumor Cells, CulturedABSTRACT
In cell culture, azelaic acid (C9) has been shown to have an antiproliferative and cytotoxic effect on human and murine malignant cutaneous melanocytes. Normal melanocytes are unaffected, as are normal choroidal melanocytes. Here, effects on cell kinetics and ultrastructure of cells of a human choroidal melanoma line have been studied. Cells were exposed to single doses of disodium salts of azelaic (C(9)2Na) and adipic (C(6)2Na) acids at concentrations of 10(-2) M and 5 X 10(-2) M for 48 hr. C(9)2Na at 5 X 10(-2) M had a significant effect on proliferation at 24 and 48 hr and this was not reversible on removal of diacid. At 5 X 10(-2) M for 24 hr, C(6)2Na had no effect and at 5 X 10(-2) M for 48 hr had an effect which was marginally significant, but reversible. Swelling and disruption of mitochondria was seen in cells exposed to C(9)2Na at 5 X 10(-2) M for 1 hr and longer, but even at 10(-1) M, cells exposed to C(6)2Na were minimally affected. The results could encourage further investigations of the feasibility of azelaic acid therapy for uveal and ocular adnexal melanoma.
Subject(s)
Adipates/pharmacology , Choroid Neoplasms/pathology , Dicarboxylic Acids/pharmacology , Melanoma/pathology , Tumor Cells, Cultured/drug effects , Cell Count/drug effects , Choroid Neoplasms/ultrastructure , Humans , Melanocytes/drug effects , Melanocytes/pathology , Melanocytes/ultrastructure , Melanoma/ultrastructure , Microscopy, Electron , Osmolar ConcentrationABSTRACT
The cytotoxic effect of azelaic acid on murine melanoma cells in culture is due, at least in part, to an antimitochondrial action. We investigated the possibility that the addition of carnitine to the medium may increase the transport of azelaic acid into the mitochondria and thereby increase its cytotoxic effect. Using mitochondrial cross-sectional area measured from electron micrographs as a criterion for mitochondrial damage, we found that the addition of L-carnitine to the culture medium had no effect either alone or with a low (10(-3) M) concentration of azelaic acid. At a high concentration (5 X 10(-2) M) azelaic acid caused swelling and disruption of the mitochondria to such an extent that this was not increased by carnitine. At 10(-2) M azelaic acid, however, some swelling of the mitochondria occurred which was significantly increased by the addition of carnitine. This indicates that carnitine-mediated transport of the diacid into the mitochondria had occurred. We conclude that carnitine may reduce the time or concentration needed for azelaic acid to have a toxic effect on the malignant melanocyte.
Subject(s)
Antineoplastic Agents/pharmacology , Carnitine/pharmacology , Dicarboxylic Acids/pharmacology , Melanoma/ultrastructure , Animals , Cell Line , Mice , Mitochondria/drug effects , Mitochondria/ultrastructureABSTRACT
Clinically, dicarboxylic acids have a cytotoxic effect on the abnormally hyperactive and malignant epidermal melanocyte, and diacids from C8 to C13 have been shown to inhibit mitochondrial oxidoreductases. Here, their effect on the growth kinetics and ultrastructure of murine melanoma cells in culture is examined. Cultures of Harding-Passey and Cloudman S91 melanoma cells were exposed to single doses of the disodium salts of C12, C9, and C6 (which does not significantly inhibit mitochondrial enzymes) dicarboxylic acids at concentrations of 10(-3) M to 10(-1) M. With C12 and C9, viability and cell proliferation over 3 days were significantly affected by concentrations greater than 10(-2) M. With exposure to C6 at 10(-1) M and to medium to which NaCl was added to produce equal osmolarity, the effect was much less. Electron microscopy of cells exposed to C9 at 10(-1) M for 1 h and 6 h revealed massive swelling of mitochondria with destruction of cristae, but plasma and nuclear membranes and membranes of endoplasmic reticulum were intact. Similar damage was not seen with C6 at 10(-1) M nor with equiosomolar NaCl. The results confirm (1) the cytotoxicity of dicarboxylic acids for malignant melanocytes, and (2) that the mitochondrion is a prime target for their action.
