Oxidative Stress in Caffeine Action on the Proliferation and Death of Human Breast Cancer Cells MCF-7 and MDA-MB-231.

To investigate the effects of caffeine on the proliferation and death of human breast cancer cells MCF-7 and MDA-MB-231. Cells were exposed to 1, 2.5, 5 and 10 mM of caffeine during 24 h, and oxidative stress (OS), cell proliferation and death, metabolic activity and DNA lesions were evaluated in the collected samples. Caffeine was cytotoxic to the cell lines analyzed, reducing cell proliferation and viability by interfering with the cellular metabolism and with lysosomal function. Although the cells presented different behaviors to treatment, in both cell lines, the drug induced OS and predominantly apoptosis. MCF-7 cells responded to OS induction (lipid peroxidation) increasing their antioxidant defenses. However, the OS generated induced oxidative DNA lesions, a finding not observed in MDA-MB-231 cells. The association of different scavengers with caffeine did not result in the recovery of cell viability, which suggests that it is not possible to attribute the caffeine induction of OS to only one of the specific ROS analyzed (superoxide anion, singlet oxygen and peroxyl radical). These results are promising and suggest that caffeine may be a good target for studies to prove its usefulness as an adjuvant in breast cancer treatment.

Systemic oxidative profile after tumor removal and the tumor microenvironment in melanoma patients.

This study highlights the systemic oxidative changes in patients submitted to primary cutaneous melanoma removal. Cutaneous melanoma is highly aggressive and its incidence is increasing worldwide. We evaluated systemic oxidative stress (OS) and 3-nitrotyrosine (3-NT) expression in melanoma tissue in relation to the Breslow thickness in patients under surveillance. Forty-three patients with cutaneous melanoma and 50 healthy volunteers were recruited. Patients were divided into two groups according to the tumor's Breslow thickness: T1/T2 (<2 mm) and T3/T4 (≥2 mm). Systemic OS and inflammatory mediators were evaluated in plasma, and the 3-NT expression was analyzed via immunohistochemistry. Compared with the controls, the patients had lower blood levels of reduced glutathione, higher malondialdehyde and thiol levels, and a higher total radical-trapping antioxidant parameter to uric acid ratio. The C-reactive protein and γ-glutamyl transpeptidase were increased only in the T3/T4 group. High levels of 3-NT were present only in T3/T4 patients. Our data suggested that a correlation exists between the Breslow thickness and a systemic pro-oxidant status, and that oxidative changes induced by the melanoma remain in the microenvironment post-surgery, demonstrating a role for oxygen species in melanoma.