Question

Explain the connection between cancer and control of the cell cycle.

Short answer

Cancer is linked to the control of the cell cycle in that disruptions in the normal function of the cell cycle can lead to uncontrolled growth and multiplication of cells. The anomalies can occur due to overexpression or reduced activity of the proteins that regulate the cell cycle or due to mutations in the genes that control these processes. Understanding this connection has resulted in the development of targeted cancer therapies that interrupt the cell cycle and stop the proliferation of cancer cells.

Step-by-step solution

Understanding the Cell Cycle

The cell cycle is a sequence of stages through which a cell passes and at the end of which it divides into two daughter cells. This process occurs in a highly regulated manner and includes four phases: G1 (gap 1), S (synthesis), G2 (gap 2), and M (mitosis or cell division). The transition of a cell from one phase to the next is regulated by a set of proteins known as cyclins and cyclin-dependent kinases (CDKs). Anomalies in the activity or expression of these proteins can lead to uncontrolled cell proliferation.

Link between Cell Cycle Control and Cancer

Cancer is characterized by the uncontrolled growth and multiplication of cells. It is caused when the normal control mechanisms of the cell cycle are disrupted. It may occur due to the overexpression of proteins that promote cell cycle progression (like cyclins and CDKs) or due to the reduced activity of proteins that inhibit cell cycle progression (like tumor suppressor proteins). This may result in the cells dividing uncontrollably, leading to the development of a tumor.

Role of Mutations

Mutations in the genes that control the cell cycle can result in cancer. Oncogenes are mutated forms of normal genes (proto-oncogenes) that regulate cell growth and division. When these oncogenes are activated, they can drive uncontrolled cell division, leading to cancer. On the other hand, mutations can also occur in tumor suppressor genes, which normally inhibit cell division and prevent the formation of tumors. When these genes are deactivated due to mutations, they lose their function, resulting in uncontrolled cell division.

Cancer Treatments Targeting the Cell Cycle

Understanding the link between the cell cycle and cancer has led to the development of targeted therapies that can interrupt the cell cycle and stop the growth of cancer cells. Some anticancer drugs target the proteins involved in promoting the cell cycle, while others boost the function of the proteins that inhibit the cell cycle. These therapies have shown to be effective in halting the growth of cancerous cells and reducing the size of tumors.