Cancer treatment is still of the greatest challenges that health care providers and patients are facing. One of the unsolved problems in cancer treatment is cells’ reaction to metabolic stress caused by harsh nutritional conditions around tumor. In order to be able to treat this disease properly, it is important to understand the true nature of the disease. In fact, the cells inside the central part of the tumor lack sufficient access to blood vessels, nutrients, and growth signals. After tumor shrinkage, the cells are exposed to favorable environmental conditions and might regrow and cause tumor recurrence. The main purpose of this study was to investigate the effect of serum starvation, as a type of metabolic stress, on human lung cancer cell line, A549. These cells were treated with 10% (control), 0. 5% and 0. 25% serum for 1 to 5 days. At 24 h intervals, the cells were released with 10% serum supplemented media. Starved or released cells were studied for their cycle and morphology. The results showed that the cells were actually arrested at G1 phase and following exposure to optimal conditions, the cells could be back to their cycle again. Furthermore, sub-G1 apoptotic cells population was not increased within the starvation period, while control cells had significant increase in sub-G1 cells. Morphological studies also showed that starved cells could make denser colonies while control cells were entering death phase. These observations provide some evidence for the generation of some effective resistance phenomena in cancer cells against harsh metabolic conditions.

The metabolic syndrome (MS) recognized as a major cause of type 2 diabetes and cardiovascular diseases, has become one of the major public health challenges worldwide. The pathogenesis of the metabolic syndrome is multiple and still poorly understood. No single factor has yet been identified as an underlying causal factor. There is a growing belief, however, that obesity, specially visceral obesity, may play an important role in the development of the syndrome. Visceral adiposity seems to be an independent predictor of insulin sensitivity, impaired glucose tolerance, dyslipidaemia and elevated blood pressure. An increasing number of studies confirm that oxidative stress, chronic inflammation and angiogenesis all play important roles in the pathogenesis of MS. Chronic hyperglycemia causes oxidative stress in tissues prone to complications in patients with diabetes. Oxidative stress occurs in a cellular system when the production of free radical moieties exceeds the antioxidant capacity of that system. If cellular antioxidants do not remove free radicals, radicals attack and damage proteins, lipids, and nucleic acids. The oxidized or nitrosylated products of free radical attack have decreased biological activity, leading to loss of energy metabolism, cell signaling, transport, and other major functions. These altered products are also targeted for proteosome degradation, further decreasing cellular function. Accumulation of such injury ultimately leads a cell to die through necrotic or apoptotic mechanisms.In conclusion, a puzzle of many pieces of evidence suggests that free radical overgeneration may be considered the key in the generation of insulin resistance, diabetes, and cardiovascular disease.