The replication of cells has long been known to be responsible for tissue, organ, and species growth and reproduction. This, of course, is a highly regulated and controlled process that results in numerous differentiated cells performing a variety of specific tasks. Cancer on the other hand is uncontrolled growth of cells, where cellular differentiation is often lost.
Proliferating cells (normal and cancerous) repeatedly transition between cellular duplication (interphase) and cell division (mitosis). This repetitive process has been described as a cycle. The concept of cell cycle was first utilized to describe these repetitive elements. The terminology (G0, G1, S, G2, and M) attempts to place in temporal perspective two dichotomies; mitosis (M), which can be determined by direct observation, and DNA synthesis (S), which can be established by DNA labeling. G1, the post mitotic gap, G2 the post-synthetic phase or pre-mitotic gap; and G0, a phase in which non-dividing cells exist, are terms used for simplicity (Figure 1).
|Figure 1. Schematic of the Cell Cycle|
|Figure 2. Plot of Lifetime Cancer risk vs. Total Stem Cell Divisions of Various Organs .|
Cancer has touched all of us in some way. Very few have not had a family member or friend be diagnosed with or die of cancer. While these data suggest that many cancers are not preventable, they reinforce the need for better early diagnosis and effective treatments for cancers. Most of those afflicted want to know why they have cancer and if they could have avoided it somehow. While the 3-pack a day smoker who gets lung cancer has a pretty good idea as to why they were afflicted, for many others the answer really is bad luck.
- Tomasetti, C. and B. Vogelstein (2014) Variation in Cancer Risk among Tissues can be explained by the Number of Stem Cell Divisions, Science, 347:78-81.
By: BioTek Instruments, Paul Held Ph.D., Laboratory Manager