Inhibition by oral N-acetylcysteine of doxorubicin-induced clastogenicity and alopecia, and prevention of primary tumors and lung micrometastases in mice.

Abstract

The thiol N-acetylcysteine (NAC), an analog and precursor of glutathione, displays cancer preventive properties not only in early stages of the carcinogenesis process but also in its advanced stages. NAC inhibited type-IV collagenase activity as well as invasion, tumor take, and metastasis of malignant cells in murine models. Previously, we provided evidence for synergistic effects of oral NAC with intravenously injected doxorubicin (DOX). In the present study B16-BL6 melanoma cells were injected s.c. into the footpad of C57BL/6 mice. The animals were divided into 5 groups: i) untreated mice; ii) mice receiving daily NAC with drinking water (12.25 mmol/kg body weight) starting 16 h after injection of cancer cells; iii) mice receiving a single i.v. injection of DOX (2 micromol/kg body weight) 24 h after injection of cancer cells; iv) mice receiving a combination of NAC and DOX, with NAC treatment starting 72 h before injection of cancer cells; and v) mice treated as in iv) but with NAC treatment starting 16 h after injection of cancer cells. Both NAC and DOX, either individually or in combination, significantly enhanced the survival time as compared to controls. The weight of local primary tumors was significantly decreased by either drug, and was further decreased to a significant extent, compared to the individual treatments, in the two groups of mice receiving combinations of NAC and DOX. No lung micrometastases, evaluated by immunohistochemistry as S-100-positive foci of melanocytic cells, were detectable in the two groups of mice receiving the combined treatments. NAC significantly, attenuated the time-related increase of micronucleated polychromatic erythrocytes in the peripheral blood of DOX-treated mice. All mice individually treated with DOX developed a partial but well evident alopecia, diffusely affecting their back hair, which was totally prevented by NAC, irrespective of the combination schedule. Thus, besides preventing DOX cardiotoxicity, as extensively documented in the literature, oral NAC protects mice from DOX-induced myelogenotoxicity and alopecia, and at the same time interacts with this cytotoxic agent in inhibiting cancer cell invasion and metastasis.