Question

Hypothesize about tumor growth. Scientists have shown that tumor growth is an example of positive feedback loops. Why is tumor growth an example of positive feedback? In your answer elaborate using the following terms stimulus, receptor, control center, effector, response.

Answer 1

Tumor growth is a process associated with the expression of oncogenic genes

Explanation:

The tumor cells often share oncogenic receptors that are expressed during oncogenesis. For example, it has been shown that the epidermal growth factor receptor is often mutated in brain cancer cells, thereby encoding an oncogenic that is overactive. These receptors are responsive to stimulus of nearby cells and thus act as effectors that amplify tumorigenic signals. In consequence, during tumor progression, tumorigenic effector cells have an uncontrolled proliferation and antiapoptotic signals are predominant. The nucleus in the cell functions as a control center where tumor suppressor genes are transcribed to fight against such oncogenic cells.