Human Lung Carcinoma Reaction against Metabolic Serum Deficiency Stress

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.