Normal cells undergo normal division which can be controlled by inhibitors, while cancer cells split rapidly in an unorganized manner and even in the presence of inhibitors. The rapid uncontrollable division by cancer cells forms the basis of the difference between normal cells and cancer cells. Mitotic index (MI) is a measure of rating cell division.
Cancer Cells and Normal Cells Compared
Cancer cells undergo the cell cycle repeatedly. In cancerous tissue, cancer cells divide over and over and with time the cells fill up the volume they are occupying resulting in the incapacitation of the process of mitosis. Also, it is observed that when they exhibit contact with the neighboring cells, they pile up on top of each other and grow in multiple layers. This implies that they have lost all restraints. Additionally, cancer cells continue to grow even in presence of growth inhibitory factors. Their growth is disorganized. They spend more time in the mitosis phase during a cell cycle (Virtual Lab, 2012).
In culture cells, normal cells continue to grow until the culture is covered by one layer of cells. At this level, the further division is impossible as space is severely limited. Normal cells undergo cell division in a more organized manner; growth in these cells is only possible through stimulation through a proper channel. Normal cells stop the process of division upon getting in touch with other cells.
Ovarian cancer cells show aggressive cancer growth. This is shown by the fact that they have the highest value of the mitotic index (MI). Using the data obtained from the lab (Virtual Lab, 2012), the following calculations are made possible:
Normal lung cells Normal stomach cells Normal ovarian cells:
- Interphase 19 18 18
- Prophase 1 0 0
- Metaphase 0 1 1
- Anaphase 0 0 2
- Telophase 0 1 0
- Total cells 20 20 21
Cancerous Lung cells Cancerous Stomach cells Cancerous ovarian cells:
- Interphase 18 14 11
- Prophase 0 2 2
- Metaphase 0 1 2
- Anaphase 1 1 3
- Telophase 1 2 2
- Total cells 20 20 20
It is through division that a cell population grows. The cell passes through interphase and mitosis for a complete cell cycle. Normal cells retard in their divisive ability as they age. It is, therefore, important to quantify the aspect of cell division (Han, 2010). Mitotic index is defined as a measure of the proliferation of a cell. It is the ratio of cell population in mitosis and the total cell population. Cancer cells have a higher mitotic index because of the uncontrollable division in mitosis. For example, normal lung tissue has 5% MI whilst the cancerous one has 25%
Mitotic index average
- Normal Lung = (19/20) + (19/20)/2= 95% Mitotic Index= 100-95=5%
- Normal Stomach= (19/20) + (19/20)/2= 95% Mitotic index=100-95=5%
- Normal Ovary= (18/20) + (19/20)/2= 92.5% Mitotic index=100- 92.5%= 7.5%
- Cancerous Lung cells= (18/20) + (3/20) =75% Mitotic index= 100-75= 25%
- Cancerous Stomach = (14/20) + (13/20)/2=67.5% Mitotic index= 100-67.5%= 32.5%
- Ovary Cancerous= (12/20) + (10/20)/2= 55% Mitotic index=100-55=55%
In general, the mitotic index decreases with an increase in cell division. The mitotic index is important in quantifying differences in cell division between the normal and cancerous cells. Cancer cells are hard to control and consequently, their uncontrolled growth leads to various problems. Cancerous tissues will have a higher mitotic index than normal tissues because of the rapid cell division in cancerous tissues (Missailidis, 2007).
Han, H. (2010). Drug Discovery in Pancreatic Cancer: Models and Techniques. New York, NY: Springer.
Missailidis, S. (2007). The Cancer Clock. New York, NY: John Willey and Sons.
Virtual Lab. (2012). Cell Reproduction. McGraw-Hill Companies. Web.