How normal cells get transformed into cancerous neoplastic cells? Mention the difference between viral oncogenes and cellular oncogens.
Answers
How is a normal cell transformed into a cancerous cell? The proteins involved in regulating cell division events no longer appropriately drive progression from one cell cycle stage to the next. Rather than lacking function, cancer cells reproduce at a rate far beyond the normally tightly regulated boundaries of the cell cycle. Cancer can be distinguished from many other human diseases because its root cause is not a lack of, or reduction in, cell function. For example, individuals with diabetes may lack insulin production or the ability to respond to insulin. With coronary heart disease, poor blood supply to the heart can cause the organ to eventually fail. In the case of acquired immune deficiency syndrome (AIDS), the immune system loses the cells it needs to fend off infection. And with many infectious diseases, foreign microorganisms wreak havoc on the host they have invaded, causing a loss of function within cells, tissues or entire organ systems. Cancers, however, occur due to an alteration of a normal biological process — cell division.
Cells that progress through the cell cycle unchecked may eventually form malignant tumors, where masses of cells grow and divide uncontrollably, then develop the ability to spread and migrate throughout the body. Fortunately, cancer prevention usually occurs through the strict regulation of the cell cycle by groups of proteins that interact with each other in a very specific sequence of events. It is these events that determine whether the cell cycle will go forward or remain stalled between stages.