Molecular Basis of Cancer Flashcards

A set of practice flashcards covering the molecular and genetic basis of cancer based on Dr. Ilija Arar's lecture notes.

Molecular Etiology of Neoplasia

Defined as genetic mutation, specifically alterations in nuclear DNA sequences (genes).

DNA Point mutations

An example of a DNA mutation involving a change in a single nucleotide base within the sequence.

Chromosomal Translocation

A genomic abnormality and type of DNA mutation where segments of chromosomes are moved.

Gene Amplification

A type of DNA mutation characterized by the increase in the number of copies of a specific gene.

Proto-oncogenes

Cellular genes that promote normal growth and differentiation; they may become oncogenic through viral or other exogenous influences.

Anti-oncogenes

Also known as cancer suppressor genes, these are growth-inhibiting genes that regulate cell growth.

Hyperplasia

A condition during neoplastic progression where altered cells look normal but reproduce excessively.

Dysplasia

A state where cells exhibit abnormal shapes and orientations in addition to proliferating excessively.

In situ cancer

A tumor that has become abnormal in growth and appearance but remains contained and has not yet broken through tissue boundaries.

Invasive cancer

A malignant mass that has acquired mutations allowing it to invade underlying tissue and shed cells into blood or lymph.

Metastases

New lethal tumors established throughout the body by renegade cells from a primary malignant tumor.

Oncogenes

Genes that promote neoplastic growth and exist as mutations of naturally occurring proto-oncogenes.

Oncoproteins

Proteins encoded by oncogenes that lack important regulatory functions and are produced without dependency on growth factors or external signals.

sis

An oncogene that encodes for Platelet Derived Growth Factor ($PDGF$).

Growth factor receptors

Transmembrane proteins with an external ligand-binding domain and a cytoplasmic tyrosine kinase domain that provide mitogenic signals.

ret

An example of a growth factor receptor linked to neoplasia due to its continuous activation of enzyme activity.

erb

An example of a growth factor receptor that promotes neoplasia via overexpression.

ras protein

A member of the $G$-protein family present in mutated forms in $10$-$20\%$ of all human cancers; the mutation maintains it in an activated state.

GAP

A protein involved in the inactivation of $ras$ through the hydrolysis of $GTP$ to $GDP$.

Nuclear Regulatory Proteins

Proteins localized in the nucleus that bind to DNA and activate transcription of proto-oncogenes, including $myc$, $jun$, and $fos$.

Two-hit hypothesis

A hypothesis stating that the inactivation of recessive anti-oncogenes leads to neoplasia only when both alleles are mutated.

RB

A cancer suppressor gene associated with retinoblastoma and osteosarcoma.

p53

A protein that links cell damage with DNA repair, cell-cycle arrest, and apoptosis; it causes $G_1$ arrest by inducing repair genes.

Li Fraumeni syndrome

A clinical syndrome associated with mutations in the $p53$ cancer suppressor gene.

BRCA

A specific cancer suppressor gene associated with breast carcinoma.

APC

A cancer suppressor gene associated with colon carcinoma.

p21

A $CDK$ inhibitor transcriptionally up-regulated by $p53$ to facilitate $G_1$ cell cycle arrest.

GADD45

A gene involved in DNA repair that is a target for up-regulation by $p53$.

BAX

A pro-apoptotic gene whose interaction/balance with anti-apoptotic genes dictates programmed cell death; its deletion can lead to malignancy.

bcl-2

An anti-apoptotic gene whose overexpression is frequently found in malignant lymphoma.

Telomeres

The tips of chromosomes that shorten as normal cells divide, serving as a cell-clock.

Telomerase

An enzyme that prevents chromosome shortening by adding nucleotides; it is absent in somatic cells but may be reactivated in cancer cells.

Bloom's Syndrome

A genetic condition associated with a high leukemia risk of $1$ in $8$.

DCC

A familial cancer gene associated with colon cancer.