cell bio (cancer)

Oncogene

A gene that when mutated or overexpressed promotes uncontrolled cell growth and proliferation

Proto-oncogene

A normal gene that regulates cell growth but can become an oncogene after mutation

Tumor suppressor gene

A gene that inhibits cell division or promotes apoptosis; loss-of-function mutations contribute to cancer

Gain-of-function mutation

A mutation that increases activity of a protein

Loss-of-function mutation

A mutation that reduces or eliminates protein function

Driver mutation

A mutation that directly contributes to cancer progression by providing growth advantage

Passenger mutation

A mutation that does not contribute to cancer progression but accumulates alongside driver mutations

Point mutation

A single nucleotide change that can activate oncogenes or inactivate tumor suppressors

Missense mutation

A mutation that changes one amino acid in a protein

Nonsense mutation

A mutation that introduces a premature stop codon

Silent mutation

A nucleotide change that does not alter the amino acid sequence

Frameshift mutation

An insertion or deletion that shifts the reading frame

Insertion mutation

Addition of nucleotides into DNA sequence

Deletion mutation

Removal of nucleotides from DNA sequence

Gene amplification

Increase in the number of copies of a gene

Chromosomal translocation

Rearrangement of parts between nonhomologous chromosomes

Fusion gene

A hybrid gene formed from two previously separate genes

Copy number variation

Changes in the number of copies of a gene that can affect gene expression

Epigenetic modification

Heritable changes in gene expression without altering DNA sequence

DNA methylation

Addition of methyl groups to DNA

Histone modification

Chemical changes to histone proteins affecting chromatin structure and gene expression

Loss of heterozygosity (LOH)

Loss of the normal allele in a heterozygous cell

Two-hit hypothesis

Concept that both alleles of a tumor suppressor gene must be inactivated for cancer to develop

Apoptosis

Programmed cell death that is often suppressed in cancer cells

Cell cycle checkpoint

Regulatory mechanism ensuring proper cell division; often disrupted in cancer

p53

A tumor suppressor protein that regulates cell cycle arrest and apoptosis in response to DNA damage

RB (Retinoblastoma protein)

A tumor suppressor that controls progression from G1 to S phase

RAS

A proto-oncogene encoding a GTPase involved in cell signaling; mutations lead to constant activation

MYC

A transcription factor oncogene that promotes cell growth and proliferation

Telomerase activation

Reactivation of telomerase in cancer cells allowing unlimited replication

Angiogenesis

Formation of new blood vessels to supply tumors with nutrients and oxygen

Metastasis

Spread of cancer cells from primary tumor to distant sites

Genomic instability

Increased tendency for mutations

DNA repair gene mutation

Defects in DNA repair mechanisms leading to accumulation of mutations

Carcinogen

A substance capable of causing cancer by inducing mutations

Clonal expansion

Growth of a population of cells derived from a single mutated ancestor

Tumor heterogeneity

Presence of genetically diverse cells within a tumor