Abnormal cell growth is primarily caused by changes in DNA that lead to the activation of oncogenes and/or the inactivation of tumor suppressor genes.
Understanding the Mechanisms
The human body’s cells normally grow and divide in a controlled manner. However, this process can go awry, leading to abnormal growth. This happens due to changes in the genes that regulate cell growth.
Oncogenes: The Accelerators of Cell Growth
- What are they? Oncogenes are genes that, when activated, promote excessive cell growth and division.
- How do they form? These genes originate from normal genes involved in cell growth that have undergone a DNA mutation.
- How do they function? Unlike normal genes, oncogenes cannot be turned off, leading to continuous and uncontrolled cell proliferation.
- Example: Imagine a car’s accelerator pedal getting stuck; the car keeps speeding up without any control.
Tumor Suppressor Genes: The Brakes on Cell Growth
- What are they? Tumor suppressor genes are the body's natural defense against cancer. They help control cell growth and prevent the development of tumors.
- How do they function? They act like brakes on cell division, slowing it down or stopping it when needed. They also repair DNA damage and promote cell death (apoptosis) in damaged cells.
- What happens when they fail? When tumor suppressor genes are inactivated, damaged cells can grow unchecked, as the body's defense mechanism is compromised.
- Example: Think of the car’s brakes failing; the car cannot slow down, leading to dangerous situations.
How DNA Changes Lead to Abnormal Growth
A change in DNA sequence can lead to two main scenarios:
- Activation of Oncogenes: A DNA mutation can transform a normal gene into an oncogene. The oncogene then promotes excessive cell division.
- Inactivation of Tumor Suppressor Genes: A DNA mutation can disable tumor suppressor genes, which means the body loses its ability to halt cell growth, repair DNA, and cause cell death of abnormal cells.
Summary of Causes
Here's a simple table summarizing the causes of abnormal cell growth:
| Cause | Description | Effect on Cell Growth |
|---|---|---|
| Oncogene Activation | A normal gene involved in cell growth becomes permanently "switched on." | Uncontrolled cell growth |
| Tumor Suppressor Inactivation | Genes that normally slow or stop cell growth are disabled or lose function. | Uncontrolled cell growth |
Practical Insight
Understanding these mechanisms is crucial in the development of cancer treatments. Many therapies now target oncogenes or aim to restore the function of tumor suppressor genes to control the excessive cell growth.
