Epigenetics and Cancer Concepts

Vocabulary practice flashcards covering key definitions, mechanisms, and stages of epigenetics, gene expression, and carcinogenesis from PHLT 304 lecture notes.

Gene expression

The process by which a gene is used to produce a protein molecule.

Epigenetics

The study of changes caused by activating or silencing genes (increasing or decreasing gene expression) without any change in the underlying DNA sequence.

Epigenome

A flexible layer of chemical tags covering DNA and histones that shapes the physical structure of the genome and adjusts gene expression in response to environmental signals such as diet and stress.

Nucleosome

A basic structural unit of chromatin formed by DNA wrapping around a core of eight histone proteins.

Solenoid

A coiled structural level of chromatin where each turn consists of approximately $6\text{ nucleosomes}$.

Chromatin loop

A structural fold organized from solenoids, with each loop containing approximately $100{,}000\text{ base pairs}$ of DNA.

DNA methylation

An epigenetic mechanism involving the reversible addition of a methyl group directly onto DNA, which typically reduces expression of a nearby gene.

Histone acetylation

An epigenetic modification involving the addition of an acetyl group to histones, which weakens interactions between histones and DNA to facilitate transcription.

Agouti gene

A gene in mice that, when unmethylated, is expressed to produce yellow coat color and obesity, as well as higher adult risk for diabetes and cancer.

Sulforaphane

A dietary compound found in broccoli that increases histone acetylation, leading to the activation of anti-cancer genes.

Butyrate

A compound produced in the intestine when dietary fiber is fermented that increases histone acetylation to activate protective genes and increase lifespan.

Diallyl sulphide (DADS)

A dietary compound found in garlic that increases histone acetylation to turn on anti-cancer genes.

Dutch Hunger Winter of 1944-1945

A period of severe gestational under-nutrition ($400\text{--}800\text{ calories/day}$) resulting in offspring being small for gestational age and developing higher adult rates of cardiovascular disease, obesity, and high blood pressure.

Neoplasia

New growth or autonomous growth of tissue.

Neoplasm

The lesion resulting from neoplasia, characterized by abnormal tissue that undergoes more rapid proliferation than normal and lacks structural organization and functional coordination.

Benign lesion

A neoplastic lesion characterized by expansive growth and slow rates of proliferation that does not invade surrounding tissues.

Malignant lesion

A neoplastic lesion demonstrating invasive growth and capable of spreading (metastases) to other tissues and organs.

Metastases

Secondary growths derived from a primary malignant neoplasm.

Genotoxic carcinogen

A physical or chemical agent that causes neoplasia by interacting directly with DNA to cause mutation.

Nongenotoxic carcinogen

A physical or chemical agent that induces neoplasia by modifying gene expression without damaging DNA.

Generation time

The time needed for a quiescent cell to complete one cell division cycle to produce $2\text{ daughter cells}$.

Quiescent cell ($G_0$ phase)

A cell in the nonproliferating resting phase of the cell cycle.

Proto-oncogene

A gene involved in normal cell growth that, when mutated into an oncogene, can stimulate pathways controlling cell proliferation, division, and angiogenesis.

Tumor suppressor gene

A gene that produces proteins to help control cell growth, whose inactivation via mutation leads to uncontrolled cell growth.

Angiogenesis

The formation of new blood vessels, which tumors require to grow.

Initiation stage

The first stage of multistage carcinogenesis involving an irreversible mutation in a somatic cell that becomes fixed if not repaired before DNA synthesis and cell division.

Somatic cell

Any cell of the body except reproductive (germ) cells.

Apoptosis

A form of programmed cell death where cell fragments are phagocytosed by other cells and eliminated without causing inflammation.

Phagocytosis

The process by which a white blood cell (phagocyte) removes dead cells and destroys foreign material such as bacteria.

Promotion stage

The stage of carcinogenesis where tumor promoters stimulate existing mutated cells to grow by altering gene expression to cause sustained cell proliferation.

Progression stage

The stage of carcinogenesis involving the conversion of benign lesions into cancerous lesions demonstrating autonomous growth and lack of growth control.

American Cancer Society warning signals

The seven warning signs of cancer summarized by C.A.U.T.I.O.N.: Change in bowel/bladder habits, A sore that does not heal, Unusual bleeding or discharge, Thickening or lump, Indigestion/swallowing difficulty, Obvious change in mole/wart, Nagging cough/hoarseness.

Indole-3-carbinol (I3C)

A compound produced by Cruciferae/Brassica vegetables that decreases tumor proliferation, induces $G_1/S$ cell cycle arrest, reduces inflammation and metastasis, and promotes apoptosis.