Cancer Genetics

What is cancer?

A group of diseases characterized by unregulated cell division and proliferation.

Define a benign tumor.

A tumor that remains localized and does not invade nearby tissues.

Define a malignant tumor.

A tumor that invades nearby tissues and can metastasize, spreading to other regions of the body.

What is metastasis?

The process by which cancer cells leave the original tumor site, travel to other parts of the body, and form new tumors.

What is the multistep model of cancer?

A model stating that mutations accumulate within a cell over time, leading to tumor formation when enough are present.

What are proto-oncogenes?

Normal genes that promote cell growth but can become oncogenes when mutated.

What are oncogenes?

Mutated forms of proto-oncogenes that lead to increased cell proliferation.

What are tumor suppressor genes?

Genes that help regulate cell division and prevent uncontrolled growth; mutations can lead to cancer.

Describe the G1/S checkpoint.

A regulatory point in the cell cycle where the cell assesses whether to proceed to DNA synthesis, involving proteins like Cdk, cyclin, Rb, and E2F.

How do DNA repair mechanisms contribute to cancer?

Ineffective DNA repair can lead to mutations that accumulate, increasing the risk of cancer.

What is DNA methylation?

A biochemical process that suppresses gene expression by adding methyl groups to DNA, typically at CpG islands.

What is the role of p53 in cancer?

A tumor suppressor gene that activates DNA repair, arrests growth at the G1/S checkpoint, and initiates apoptosis.

How does the mutation of p53 affect cancer?

Mutations or deletions of p53 are found in over 50% of cancers, contributing to unregulated cell growth.

What happens when Rb gene is mutated?

A mutation in the Rb gene can produce a protein that fails to bind to E2F, potentially leading to tumor formation.

What is the significance of methylation of the MGMT promoter?

Methylation of the MGMT promoter can inhibit the expression of DNA repair proteins, contributing to cancer development.

What impact would p21 methylation of the P53 promoter have on cell cycle regulation?

It may reduce the expression of p21, impairing cell cycle arrest and potentially leading to uncontrolled proliferation.