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.

Pulmonary Emphysema Impairs Male Reproductive Physiology Due To Testosterone and Oxidative Stress Imbalance in Mesocricetus auratus.

This study evaluated whether pulmonary emphysema affects sperm quality, male reproductive organs, and testosterone levels in adult male hamsters. Mesocricetus auratus males (130-150 g) were subdivided into a control group (C group) and an emphysema group (E group). The C group received an intratracheal instillation of saline solution (0.3 mL/100 g of body weight), and the E group received papain (40 mg/100 g of body weight). After 60 days, the biometric, pulmonary, and reproductive parameters of each group were evaluated. The E group developed pulmonary emphysema, which decreased body weight and sperm quality compared to the C group. In oxidative stress-related assays, lipid peroxidation was increased in the testis and epididymis (caput and cauda) in the E group compared with the C group. However, only the caput epididymis showed a reduction in glutathione levels. Pulmonary emphysema also affected the testicle by inducing an increase in abnormal seminiferous tubules, accompanied by a decrease in seminiferous epithelium height. Spermatogenesis kinetics were also modified by pulmonary emphysema. The number of Leydig and Sertoli cells decreased in the E group, accompanied by an increase in the nuclear volume of Leydig cells. Testosterone concentration was increased in the E group. Similarly, pulmonary emphysema altered epididymal components in all regions. In conclusion, pulmonary emphysema affected the reproductive system in this experimental model, as shown by testicular and epididymal morphophysiology changes, hormonal alteration, and oxidative stress imbalance, inducing the loss of correct function in the male reproductive system.

Metformin prevention of doxorubicin resistance in MCF-7 and MDA-MB-231 involves oxidative stress generation and modulation of cell adaptation genes.

Metformin was shown to sensitize multidrug resistant breast cancer cells; however, the mechanisms involved in this capacity need to be clarified. We investigated oxidative stress and inflammatory-related pathways during the induction of doxorubicin resistance in MCF-7 and MDA-MB-231 human breast cancer cells (DOX-res group), and evaluated metformin-induced cellular responses that resulted in the prevention of doxorubicin resistance (Met-DOX group). Microarray analysis demonstrated that DOX-res changed the expression of genes involved in oxidative stress (OS) and the TGF- ß1 pathway. The DOX-res group presented increased thiols and reduced lipoperoxidation, increased levels of nitric oxide, nuclear NF-kB and Nrf2, and reduced nuclear p53 labelling. Analysis of the TGF-ß1 signaling pathway by RT-PCR array showed that DOX-res developed adaptive responses, such as resistance against apoptosis and OS. Metformin treatment modified gene expression related to OS and the IFN-α signaling pathway. The Met-DOX group was more sensitive to DOX-induced OS, presented lower levels of nitric oxide, nuclear NF-kB and Nrf2, and increased nuclear p53. Analysis of the IFN-α signaling pathway showed that Met-DOX presented more sensitivity to apoptosis and OS. Our findings indicate that metformin is a promising tool in the prevention of chemoresistance in patients with breast cancer submitted to doxorubicin-based treatments.

Does l-glutamine-supplemented diet extenuate NO-mediated damage on myenteric plexus of Walker 256 tumor-bearing rats?

This study was designed to appraise the relationship between enteric neuropathy and oxidative stress in cancer cachexia under l-glutamine-supplemented diet. Total and nitrergic neuronal populations were investigated in jejunum and ileum in four experimental groups: control (C); control l-glutamine-supplemented diet (CG); Walker-256 tumor (TW); and Walker-256 tumor supplemented with l-glutamine (TWG). In addition, local oxidative stress, neuronal nitric oxide synthase (nNOS) enzyme and nitric oxide (NO) levels were evaluated. Neuronal density and somatic area of the total and nitrergic populations were reduced in TW rats, which was accompanied by high oxidative stress, NO and nNOS levels. l-glutamine supplementation prevented neuronal atrophy, changes in pan neuronal density and nNOS overexpression (ileum), and restored total antioxidant capacity. Nevertheless, the oxidative stress was partially mitigated and no effect was observed on the reduction of nitrergic population and NO levels. l-glutamine-supplemented diet extenuates NO-mediated damage on the myenteric plexus although has a small benefit on oxidative stress.

Mechanism of metformin action in MCF-7 and MDA-MB-231 human breast cancer cells involves oxidative stress generation, DNA damage, and transforming growth factor ß1 induction.

The participation of oxidative stress in the mechanism of metformin action in breast cancer remains unclear. We investigated the effects of clinical (6 and 30 µM) and experimental concentrations of metformin (1000 and 5000 µM) in MCF-7 and in MDA-MB-231 cells, verifying cytotoxicity, oxidative stress, DNA damage, and intracellular pathways related to cell growth and survival after 24 h of drug exposure. Clinical concentrations of metformin decreased metabolic activity of MCF-7 cells in the MTT assay, which showed increased oxidative stress and DNA damage, although cell death and impairment in the proliferative capacity were observed only at higher concentrations. The reduction in metabolic activity and proliferation in MDA-MB-231 cells was present only at experimental concentrations after 24 h of drug exposition. Oxidative stress and DNA damage were induced in this cell line at experimental concentrations. The drug decreased cytoplasmic extracellular signal-regulated kinases 1 and 2 (ERK1/2) and AKT and increased nuclear p53 and cytoplasmic transforming growth factor ß1 (TGF-ß1) in both cell lines. These findings suggest that metformin reduces cell survival by increasing reactive oxygen species, which induce DNA damage and apoptosis. A relationship between the increase in TGF-ß1 and p53 levels and the decrease in ERK1/2 and AKT was also observed. These findings suggest the mechanism of action of metformin in both breast cancer cell lineages, whereas cell line specific undergoes redox changes in the cells in which proliferation and survival signaling are modified. Taken together, these results highlight the potential clinical utility of metformin as an adjuvant during the treatment of luminal and triple-negative breast cancer.