What is the Difference Between Oncogene and Proto-Oncogene

The main difference between oncogene and proto-oncogene is that oncogene is a mutated gene that has the potential to cause cancer whereas proto-oncogene is the unmutated cancer-causing gene.

Oncogene and protooncogene are two types of cancer-causing genes. These genes are involved in the regulation of cell division.

Key Areas Covered

1. What is Oncogene
   • Definition, Characteristics, Importance
2. What is Proto-Oncogene
   • Definition, Characteristics, Importance
3. Similarities Between Oncogene and Proto-Oncogene
   • Outline of Common Features
4. Difference Between Oncogene and Proto-Oncogene
   • Comparison of Key Differences

Key Terms

Oncogene, Proto-Oncogene

What is Oncogene

An oncogene is a cellular gene (a proto-oncogene) that is dysfunctional due to mutation and fusion with another gene or overexpression. Generally, oncogenes deregulate cell proliferation and suppress apoptosis. Before undergoing mutation, oncogenes are known as proto-oncogenes. More importantly, proto-oncogenes play a key role in regulating cell division. Therefore, a mutation in proto oncogenes causes cancers by changing into oncogenes. Mutations change the function of the proto-oncogene resulting in uncontrollable cell multiplication. Normally, it pushes cells to divide again and again.

Figure 1: Oncogenes

Furthermore, the name oncogene suggests that the gene can cause cancer. The initial identification of oncogenes was in viruses and these oncogenes can cause cancer in animals. However, oncogenes are normal cellular genes that undergo mutations to get impair function, which is the regulation of cell proliferation. In addition, these oncogenes can regulate cell growth and apoptosis. Therefore, mutated copies of these genes allow uncontrolled cell division, growth, and suppressed apoptosis.  

What is Proto-Oncogene

Proto-oncogenes are a group of genes that cause normal cells to become cancerous when they are mutated. Mutations in proto-oncogenes are typically dominant in nature, and the mutated version of a proto-oncogene is called an oncogene. More importantly, proto oncogenes encode proteins that help to stimulate cell division, inhibit cell differentiation, and halt cell death. However, all of these processes are important for normal human development and for the maintenance of tissues and organs. Oncogenes, however, show impaired function that leads to increased cell division, decreased cell differentiation, and inhibition of cell death.

Figure 2: Proto-Oncogenes

Moreover, proto-oncogenes become cancer-causing genes upon undergoing mutations. Mutated proto-oncogenes are oncogenes. Therefore, proto oncogenes are healthy genes that occur in the cell. Usually, they are responsible for producing proteins involved in cell growth, division, and apoptosis. However, mutations cause a change in the function of the proto-oncogenes. This results in increased cell proliferation, cell growth, and suppressed apoptosis.

Similarities Between Oncogene and Proto-Oncogene

• Oncogene and protooncogene are two types of cancer-causing genes.
• These genes help in the regulation of cell division.

Difference Between Oncogene and Proto-Oncogene

Definition

Oncogene refers to a gene having the potential to cause a normal cell to become cancerous while protooncogene refers to a group of genes that cause normal cells to become cancerous when they are mutated.

Significance

Oncogenes are mutated cancer-causing genes while proto oncogenes are unmutated cancer-causing genes.

Effect

Oncogenes undergo rapid replication, becoming out of control, while proto oncogenes do not undergo rapid replication.

Potential Cancer-Causing Genes

Oncogenes are cancer-causing genes while proto oncogenes are not cancer-causing genes.

Conclusion

In brief, oncogenes are mutated cancer-causing genes. The mutation of these genes can cause rapid cell division. Therefore, they have the potential to cause cancers. In contrast, proto oncogenes are unmutated genes. However, both oncogenes and proto oncogenes have functions in the regulation of cell division. Therefore, mutations in these genes result in rapid cell division. Actually, this causes cancer. Here, proto oncogenes are genes in the regulation of cell division that does not undergo mutations. But protooncogenes have the potential to become cancer-causing genes. Therefore, the main difference between oncogenes and proto oncogenes is their ability to cause cancer.

References:

1. “Oncogene.” gov.
2. Cafasso, Jacquelyn. “Proto-Oncogenes: Definition, Function, and Relation to Cancer.” Healthline, Healthline Media, 9 June 2018.

Image Courtesy:

1. “Oncogenes illustration” By National Cancer Institute – Own work (Public Domain) via Commons Wikimedia
2. “Ch1-oncogene” By Philippe Hupé- Own Work (CC BY-SA 3.0) via Commons Wikimedia