Cancer Biology and Cell Cycle Control

Flashcards on cancer cells, cell cycle checkpoints, and related genes.

Cancer Cells

Grow without signals, don’t die when damaged, pile on each other, develop vasculature, and metastasize.

Cell Cycle Steps Control

The cell cycle steps are very tightly controlled to ensure proper cell division.

CDKs (cyclin-dependent kinases)

Always present in the cell, but not always functional.

Cyclins

Present only during certain stages of the cell cycle.

CDK-Cyclin Complex

Cyclins bind CDKs, which then phosphorylate target proteins, leading to activation or inactivation.

Phosphorylation Effects on CDKs

CDKs can be phosphorylated (or not) to affect their function; phosphorylation can either activate or inactivate CDK.

Retinoblastoma Pathway

A pathway where CDKs and cyclins promote cell growth.

Checkpoints in Cell Cycle

G1 checkpoint (DNA damage), G2 checkpoint (DNA damage), M checkpoint (microtubule attachment).

p53 in G1 Checkpoint

p53 causes cell cycle arrest to provide time to repair DNA damage or induces apoptosis if damage is too extensive.

Extracellular Signals Promoting Cell Growth

Protein shape changes, Growth factors, Growth factor receptors, Intracellular signaling factors, and Transcription factors.

Tumor Suppressor Genes

Genes that encode proteins that prevent cell growth or repair DNA damage.

Proto-oncogenes

Genes that encode proteins that promote cell growth.

Oncogene

A mutant form of a proto-oncogene that promotes cell growth constitutively.

Philadelphia chromosome

Translocation between chromosomes 9 and 22, leading to chronic myelogenous leukemia.

Mutant tumor suppressor genes

Cannot prevent cell growth; act recessively but can appear dominant in pedigrees.

Epigenetic changes in cancer

Alter gene expression, leading to over- or under-expressed genes.

Cancer Development

Requires multiple mutations in cell cycle control genes in the same cell for progression.

Cancer Cell Karyotypes

Often show aneuploidy and rearrangements due to loss of checkpoint control.