How do cancer cells differ from normal cells regarding cell cycle control?

Cancer cells significantly differ from normal cells in their control of the cell cycle, particularly concerning checkpoints and growth factors. Normal cells are governed by a series of checkpoints that monitor and regulate the progression of the cell cycle, ensuring that cells do not divide uncontrollably. These checkpoints help prevent the development of tumors by allowing the cell to repair damage or undergo programmed cell death (apoptosis) if damage is irreparable.

In contrast, cancer cells often lack the necessary protein checkpoints that would typically regulate their division and growth. This lack of control enables them to proliferate without the usual restrictions found in normal cells. Additionally, cancer cells frequently produce their own growth factors, which stimulate their continued growth and division even in the absence of external signals that normal cells would require. This aberration in growth signaling contributes to the unchecked proliferation characteristic of tumors.

Understanding these differences provides critical insights into cancer biology and illustrates why targeted therapies often focus on reinstating or mimicking these regulatory mechanisms to control cancer cell growth.