Nitric oxide and its derivatives in the cancer battlefield.

Elevated levels of reactive nitrogen species, alteration in redox balance and deregulated redox signaling are common hallmarks of cancer progression and chemoresistance. However, depending on the cellular context, distinct reactive nitrogen species are also hypothesized to mediate cytotoxic activity and are thus used in anticancer therapies. We present here the dual face of nitric oxide and its derivatives in cancer biology. Main derivatives of nitric oxide, such as nitrogen dioxide and peroxynitrite cause cell death by inducing protein and lipid peroxidation and/or DNA damage. Moreover, they control the activity of important protein players within the pro- and anti-apoptotic signaling pathways. Thus, the control of intracellular reactive nitrogen species may become a sophisticated tool in anticancer strategies.

PTP1B phosphatase as a novel target of oleuropein activity in MCF-7 breast cancer model.

Phosphatase PTP1B has become a therapeutic target for the treatment of type 2-diabetes, whereas recent studies have revealed that PTP1B plays a pivotal role in pathophysiology and development of breast cancer. Oleuropein is a natural, phenolic compound with anticancer activity. The aim of this study was to address the question whether PTP1B constitutes a target for oleuropein in breast cancer MCF-7 cells. The cellular MCF-7 breast cancer model was used in the study. The experiments were performed using cellular viability tests, Elisa assays, immunoprecipitation, flow cytometry analyses and computer modelling. Herein, we evidenced that the reduced activity of phosphatase PTP1B after treatment with oleuropein is strictly correlated with decreased MCF-7 cellular viability and cell cycle arrest. These results provide new insight into further research on oleuropein and possible role of the compound in adjuvant treatment of breast cancer.

Anticancer Potential of Oleuropein, the Polyphenol of Olive Oil, With 2-Methoxyestradiol, Separately or in Combination, in Human Osteosarcoma Cells.

BACKGROUND/AIM: Oleuropein belongs to the potent polyphenols of olive oil. Notably, it is considered as a potentially active anticancer agent. Herein, the anticancer efficiency of oleuropein, when used separately and in combination with the chemotherapeutic agent, 2-methoxyestradiol (2-ME), was investigated in highly metastatic osteosarcoma (OS) cells. MATERIALS AND METHODS: Human OS cells (143B OS cell line) were incubated with oleuropein and 2-ME, alone or in combination. Cell viability was determined by the MTT assay. Cell migration assays were used in order to determine the anti-migratory potential of the compounds, while their impact on autophagy was evaluated via the LC3-antibody-based detection assay. The interaction between oleuropein and 2-ME was determined via the CalcuSyn software. RESULTS: Both anti-migratory and anti-proliferative effects of oleuropein were demonstrated on human OS cells. Anticancer effects of oleuropein were significantly enhanced after 2-ME addition. Treatment of 143B OS cell with oleuropein, alone or in combination with 2-ME resulted in induction of autophagy. CONCLUSION: The obtained data suggest an anticancer effect of oleuropein, alone and in combination with 2-ME, on highly metastatic 143B OS cells. Notably, a synergism between oleuropein and 2-ME towards 143B OS cells was detected. The exact mechanism of this synergism needs to be further investigated; nonetheless, induction of nitro-oxidative stress and/or induction of autophagy are suggested.

Curcumin and Cinnamaldehyde as PTP1B Inhibitors With Antidiabetic and Anticancer Potential.

BACKGROUND/AIM: Protein tyrosine phosphatase (PTP1B) is a potential target for the treatment of type 2 diabetes and cancer. Curcumin and cinnamaldehyde have been previously reported to have antidiabetic and anticancer potentials. The aim of this study was to investigate the effect of curcumin in comparison to cinnamaldehyde on the enzymatic activity of PTP1B and the viability of MCF-7 cancer cells. MATERIALS AND METHODS: Enzymatic activity and cell viability assays were utilized. Experiments were performed using the breast cancer MCF-7 cell line. RESULTS: Curcumin and cinnamaldehyde decreased the activity of PTP1B, and had inhibitory effects on the viability of MCF-7 cancer cells. Curcumin had a significantly higher inhibitory effect than cinnamaldehyde. CONCLUSION: Curcumin can be considered a potential agent for the treatment of type-2 diabetes or cancer.

2-Methoxyestradiol and Its Combination with a Natural Compound, Ferulic Acid, Induces Melanoma Cell Death via Downregulation of Hsp60 and Hsp90.

Melanoma is an aggressive type of skin cancer with one of the highest mortality rates. Notably, its incidence in the last few decades has increased faster than any other cancer. Therefore, searching for novel anticancer therapies is of great clinical importance. In the present study, we investigated the anticancer potential of 2-methoxyestradiol, potent chemotherapeutic, in the A375 melanoma cellular model. In order to furthermore evaluate the anticancer efficacy of 2-methoxyestradiol, we have additionally combined the treatment with a naturally occurring polyphenol, ferulic acid. The results were obtained using the melanoma A375 cellular model. In the study, we used MTT assay, flow cytometry, and western blot techniques. Herein, we have evidenced that the molecular mechanism of action of 2-methoxyestradiol and ferulic acid is partly related to the reduction of Hsp60 and Hsp90 levels and the induction of nitric oxide in the A375 melanoma cell model, while no changes were observed in Hsp70 expression after 2-methoxyestradiol and ferulic acid treatment separately or in combination. This is especially important in case of chemoresistance mechanisms because the accumulation of Hsp70 reduces induction of cancer cell death, thus decreasing antitumour efficacy.

Potential Health Benefits of Olive Oil and Plant Polyphenols.

Beneficial effects of natural plant polyphenols on the human body have been evaluated in a number of scientific research projects. Bioactive polyphenols are natural compounds of various chemical structures. Their sources are mostly fruits, vegetables, nuts and seeds, roots, bark, leaves of different plants, herbs, whole grain products, processed foods (dark chocolate), as well as tea, coffee, and red wine. Polyphenols are believed to reduce morbidity and/or slow down the development of cardiovascular and neurodegenerative diseases as well as cancer. Biological activity of polyphenols is strongly related to their antioxidant properties. They tend to reduce the pool of reactive oxygen species as well as to neutralize potentially carcinogenic metabolites. A broad spectrum of health-promoting properties of plant polyphenols comprises antioxidant, anti-inflammatory, anti-allergic, anti-atherogenic, anti-thrombotic, and anti-mutagenic effects. Scientific studies present the ability of polyphenols to modulate the human immune system by affecting the proliferation of white blood cells, and also the production of cytokines or other factors that participate in the immunological defense. The aim of the review is to focus on polyphenols of olive oil in context of their biological activities.