Cancer cell metabolism: its relevance to cancer treatment

Melatonin protects against oxidative stress caused by delta-aminolevulinic acid: implications for cancer reduction

delta-Aminolevulinic acid (ALA) is a precursor of haem. The increased concentration of ALA is typically related to acute intermittent porphyria, hereditary tyrosinemia, and lead poisoning. delta-Aminolevulinic acid produced in excess accumulates in a number of organs, causes oxidative damage, and often leads to cancer. Melatonin (N-acetyl-5-methoxytryptamine) is a well-known antioxidant, free radical scavenger, and exhibits anticarcinogenic properties. It protects DNA, lipids, and proteins from oxidative damage. The protective effects of melatonin against ALA-induced oxidation of guanine bases, lipid peroxidation, and alterations in membrane fluidity in several organs have been documented. There is an inverse relationship between melatonin and ALA concentrations in both experimental and clinical conditions of porphyria. The marked efficacy of melatonin in protecting against ALA-related oxidative stress, its oncostatic properties, and low toxicity constitute reasons to consider the use of this indoleamine as a co-treatment in patients suffering from disturbances related to ALA accumulation.

Role of lipids, lipoproteins and vitamins in women with breast cancer

OBJECTIVES

Improper balance between the production of reactive oxygen metabolites (ROMs), and antioxidative defense system have been defined as oxidative stress in various pathologic conditions. Lipids, lipoproteins and antioxidative vitamins have been associated with the risk of breast cancer. The present case-control study was conducted to investigate the status of antioxidative vitamins (A, C and E), lipids (total cholesterol; TC and triglycerides; TG), lipoproteins (high-density lipoprotein cholesterol; HDL-C and low-density lipoprotein cholesterol; LDL-C) and retinol-binding protein (RBP) in breast cancer patients. The aim of the study was to find out oxidative stress in breast cancer.

DESIGN AND METHODS

Plasma lipids, lipoproteins and vitamins were estimated in 54 untreated breast cancer patients of different clinical stages and in 42 age- and sex-matched controls.

RESULTS

Plasma TC (p < 0.05), and LDL-C and TG (p < 0.01) were found to be significantly elevated among breast cancer patients as compared to the controls. On the other hand, plasma HDL-C concentration (p < 0.001) and vitamin C and E (p < 0.01) were observed significantly decreased in breast cancer patients than in the controls. The maximum changes in plasma TC, and vitamin C and E concentrations were observed in breast cancer patients with stage IV when compared with controls.

CONCLUSION

The study suggests that higher levels of TC and TG may play important role in carcinogenesis. Furthermore, the elevated plasma LDL-C concentration, which is more susceptible to oxidation, may result in higher lipid peroxidation in breast cancer patients. However, decreased concentrations of HDL-C and vitamin C and E are not likely to be sufficient enough to counter higher ROMs production reported earlier in breast cancer patients that may cause oxidative stress leading to cellular and molecular damage thereby resulting in cell proliferation and malignant conversions.