PATHOLOGY

Detailed explanation-1: -The answer is simple: Oncogenes arise as a result of mutations that increase the expression level or activity of a proto-oncogene. Underlying genetic mechanisms associated with oncogene activation include the following: Point mutations, deletions, or insertions that lead to a hyperactive gene product.

Detailed explanation-2: -Before an oncogene becomes mutated, it is called a proto-oncogene, and it plays a role in regulating normal cell division. Cancer can arise when a proto-oncogene is mutated, changing it into an oncogene and causing the cell to divide and multiply uncontrollably.

Detailed explanation-3: -An oncogene is a dominantly expressed mutation which gives a cell a growth or survival advantage. An oncogene codes for a mutated form of a protein which forms part of a signal transduction pathway. An oncogene coeds for a protein which prevents the cell from undergoing apoptosis.

Detailed explanation-4: -Gene amplification (see Figure 5.54) is common in tumor cells, occurring more than a thousand times more frequently than in normal cells, and amplification of oncogenes may play a role in the progression of many tumors to more rapid growth and increasing malignancy.