Tumor Suppressor Genes: Retinoblastoma

25 vocabulary flashcards generated from the 'Tumor Suppressor Genes: Retinoblastoma' lecture notes.

Proto-oncogenes

Cancer-critical genes where a mutation leads to overactive or overexpressed versions, requiring only a single copy mutation (dominant).

Tumor Suppressor Genes

Cancer-critical genes where mutations result in loss-of-function, requiring both copies to be mutated (recessive).

Retinoblastoma

A childhood eye tumor resulting from a mutation in the Rb tumor suppressor gene.

Familial Retinoblastoma

A form of retinoblastoma characterized by multiple tumors in both eyes, with a 36% chance of developing other cancers.

Sporadic Retinoblastoma

A form of retinoblastoma characterized by a single tumor in one eye.

Loss of Heterozygosity (LOH)

The elimination of a wild-type gene copy, often through mitotic recombination, making a cell homozygous for a mutant allele.

Mitotic Recombination

The exchange of non-sister chromatids between homologous chromosomes during mitosis, a mechanism for eliminating a wild-type gene copy.

Epigenetic Modification

Changes to DNA that do not alter the DNA sequence itself, such as promoter methylation.

Promoter Methylation

An epigenetic modification where methyl groups are added to cytosine bases in the promoter region, often inactivating tumor suppressor genes by making the promoter inaccessible.

Runx3

A tumor suppressor gene implicated in stomach cancer development, frequently inactivated by promoter methylation rather than mutations.

Cell Cycle

Comprised of four successive phases (G1, S, G2, M) that a cell undergoes to grow and divide.

HDACs (Histone Deacetylases)

Enzymes that remove acetyl groups from histones, causing chromatin compaction and repressing transcription.

CTD (C-terminal domain)

A part of RNA polymerase II, whose phosphorylation by CycE-CDK2 causes HDACs to dissociate, impacting gene expression.

CycE-CDK2

A cyclin-dependent kinase complex that phosphorylates the CTD, leading to release of E2F and S-phase entry.

E2F

Transcription factors that regulate the expression of genes required for S-phase entry, inhibited by Rb.

Rb (Retinoblastoma Protein)

A tumor suppressor protein that prevents inappropriate entry into S-phase by binding to and inhibiting E2F transcription factors.

HPV (Human Papillomavirus)

A DNA virus that can cause cervical cancer by inactivating tumor suppressors like Rb.

HPV E7 viral protein

A viral oncoprotein from HPV that binds to and inactivates the Rb protein, leading to uncontrolled cell cycle entry.

G1/S Checkpoint

A critical point in the cell cycle where the cell decides whether to proceed with DNA replication, heavily regulated by Rb and E2F.

Cyclin D-CDK4

A cyclin-dependent kinase complex that phosphorylates Rb, initiating its inactivation and leading toward S-phase entry.

Chromatin Compaction

The condensation of DNA and proteins (histones) into a more compact structure, making genes less accessible for transcription, often regulated by HDACs.

Global Hypermethylation

An widespread increase in methylation across the genome observed in some cancers, particularly affecting tumor suppressor gene promoters.

Transcription

The process of copying genetic information from DNA into RNA, a process that is repressed when promoters are methylated and inaccessible.

S-phase

The phase of the cell cycle during which DNA is replicated.

DNA Replication

The biochemical process where a cell's DNA is duplicated, a key event of the S-phase, regulated by proteins like E2F.