Genes and Cancer Trivia Quiz

Answer: p53

p53 is a transcription factor. Transcription factors are proteins that bind to a specific sequence of a gene (promoter region) stimulating its transcription into mRNA, which is an intermediate template used by cells to translate genes into protein. p53 responds to DNA damage, e.g. UV light damages DNA.

This damage stabilises this protein. It can then upregulate expression of proteins needed to repair DNA, thus by this action guard the genome.

Answer: Tumour supressor gene

Tumour suppressor genes are generally involved in regulation of factors in the cell, e.g. proteins that control transcription of growth factors. Mis-function or non-function of these types of genes can therefore lead to uncontrolled growth of cells, and formation of tumours.

Answer: Knudson

Each gene has two alleles (each gene has two copies or alleles, maternal/paternal). The two-hit model suggests that the inactivation of both maternal and paternal alleles of a tumour suppressor gene are necessary for tumour development.

Answer: Increased growth of blood vessels

Angiogenesis is common in cancer because the body is very dependant on oxygen. Therefor the supply of oxygen to cells is essential. Thus control of this is tightly controlled at every level, genetic, protein and endocrine. With such complex regulation, it is inevitable that genetic defects that lead to tumour development would effect angiogenesis.

Answer: Interferon

Interferon is also a key factor of the immune system, especially in response to viruses.

Answer: Rapidly dividing cells

Tumour cells are essentially normal cells that due to genetic defects grow in an unregulated way, different types of cancer cell with have different regulatory pathways effected than others. Tumour cells characteristically grow/divide faster than "normal" cells and these cells are therefore targeted by drugs, with the consequence of effecting all rapidly dividing cells such as hair follicles, leading to hair loss.

Answer: CpG islands

Methylation is the incorporation of a methyl group to into the DNA. This methylation site is a C-G rich area within the DNA, if this is within the promoter region of a gene it prevents its expression. DNA codes for proteins using chemical groups known as bases, these are: cytosine(C), guanine(G), tyrosine (T) and adenosine (A). A, C-G rich area is a area of DNA that contains many C+G residues.

Answer: p17

Mutation of p53 is common in most types of cancer because of its important regulatory role in the genome. Rb mutation is associated with retinoblastoma. The VHL is associated with the familial cancer syndrome von Hippel-Lindau disease.

Answer: MDM2

p53 is activated and induces expression of MDM2. Inturn MDM2 transfers ubiquitin to p53 and prevents its accumulation. Ubiquitin is a small molecule that is commonly used to "tag" proteins and targets them for degradation by a cellular structure called the proteasome which is full of enzymes that degrade protein. This auto-regulatory loop prevents accumulation of p53.

Answer: E3 ubiquitin ligase

The VHL protein acts as the recognition component of this complex. VHL binds to target proteins as part of the E3 ligase complex. The E3 ligase complex tags proteins with ubiquitin and therefor targets them for proteosomal degradation much like MDM2/p53.