Question

(and the book) discussed several characteristics specific to cancer cells that are critical for their ability to proliferate and become invasive cancers, essentially out-competing normal, well-behaved cells. List two of these abnormal characteristics and explain how each of them can contribute to cancer development.

Answer 1

Cancer cells differ from normal cells in many ways. Normal cells become cancerous when a series of mutations leads the cell to grow and proliferate uncontrollably. Mutations give a cancer cell a growth advantage which by it can make more copies of itself than a normal cell can. Two of many characteristics of cancer cells are:

1. Insensitivity to anti-growth signals

cancer cells inactivate growth inhibitory signals like tumor suppressor genes, such as Rb, that normally inhibit growth. Tumor suppressor genes are important genes in normal cells that slow down cell division usually for repairing DNA mistakes. They suppress cell proliferation and signal the need for apoptosis. When tumor suppressor genes don't work properly, cells can grow out of control, which can lead to cancer. Both copies of tumor suppressor genes must be mutated within a cell for uncontrolled division to occur.

2. Evading programmed cell death

Cancer cells suppress and inactivate genes and pathways that normally enable cells to die. Apoptosis is a form of programmed cell death and is induced in case the cell is damaged. Apoptosis is required for organisms to grow and develop normally with healthy cells. Cancer cells are characteristically able to bypass this mechanism. Cancer cells change the mechanisms that detect the cell damage and so, proper signaling cannot occur. Thus apoptosis cannot be initiated, which leads to cancer.