Pathophysiology and Epidemiology of Cancer and Epigenetics

Comprehensive vocabulary flashcards covering cancer biology, epidemiology, childhood malignancies, genetics, and epigenetics from lecture notes.

Embryonal tumors

Tumors originating during intrauterine life composed of immature embryonic tissue unable to mature or differentiate into fully developed cells, commonly named with the suffix -blast.

Mesodermal germ layer

The embryonic layer from which most childhood cancers originate, giving rise to connective tissue, bone, cartilage, muscle, blood, blood vessels, gonads, kidneys, and the lymphatic system.

Epigenetics

Chemical modifications of DNA sequences that alter the expression of genes, resulting in disease and phenotypic variations without altering the underlying genetics.

DNA methylation

The attachment of a methyl group to a cytosine base followed by a guanine base (CpG dinucleotide), causing a gene to become transcriptionally inactive or silent.

Euchromatic

Refers to a DNA segment that is loosely bound to associated histones and is transcriptionally active.

Heterochromatic

Refers to a DNA segment that is tightly bound to associated histones and is transcriptionally inactive.

DNA Hydroxymethylation

An epigenetic modification most common in cells undergoing transition where a hydroxymethyl group affixes to C5 of cytosine, explaining loss of methylation in embryonic development.

Oncomirs

MicroRNAs (miRNAs) that stimulate cancer development and progression by altering the activity of oncogenes and tumor-suppressor genes.

Genomic Imprinting

The process of gene silencing in which genes are predictably silenced depending on which parent transmits them, usually associated with heavy methylation.

Neoplasm

An abnormal growth resulting from uncontrolled proliferation that serves no physiologic function.

Anaplasia

The loss of cellular differentiation and organization resulting in poorly differentiated cells, characteristic of malignant tumors.

Carcinoma in situ (CIS)

Preinvasive epithelial malignant tumors of glandular or squamous origin that have not broken through the basement membrane or invaded the surrounding stroma.

Proto-oncogenes

Normal nonmutant genes that code for cellular growth.

Oncogenes

Mutant genes that direct protein synthesis and cellular growth in an unregulated manner.

Tumor-suppressor genes

Genes encoding proteins that normally negatively regulate proliferation, also referred to as anti-oncogenes.

Caretaker genes

Genes that maintain genomic integrity by encoding proteins involved in repairing DNA replication errors or damage caused by radiation and chemicals.

Retinoblastoma protein (Rb)

A tumor suppressor protein whose inactivation or mutation leads to childhood retinoblastoma as well as many lung, breast, and bone cancers.

TP53 gene

A tumor-suppressor gene known as the guardian of the genome that monitors stress signals, activates caretaker genes, and induces cell cycle arrest or apoptosis upon DNA damage.

Telomeres

Protective caps on each chromosome maintained by telomerase that shorten with each cell division in normal body cells.

Warburg effect

The preferential use of glycolysis by cancer cells under normal oxygen conditions to produce building blocks for rapid cellular growth.

Tumor-associated macrophage (TAM)

A key cell type that promotes tumor survival by blocking cytotoxic T cell and NK cell functions, secreting cytokines for tumor growth, and promoting angiogenesis.

Epithelial-mesenchymal transition (EMT)

A process during cancer progression where epithelial cells lose polarity and adhesion, gain migratory capacity and apoptosis resistance, and dedifferentiate into a stem cell-like state.

Paraneoplastic syndromes

Symptom complexes triggered by a cancer but not caused by direct local effects of the tumor mass, mediated by hormones or antibodies released into circulation.

Cachexia

The most severe form of malnutrition in cancer patients, characterized by protein-calorie malnutrition, progressive wasting, anorexia, asthenia, and altered metabolism.

Relative risk

The ratio of the rate of a disease among individuals exposed to a risk factor compared to the incidence rate among individuals not exposed.

Incidence Rate

The number of new cases of a disease reported during a specific period divided by the total number of individuals in the population.

Prevalence Rate

The proportion of a population affected by a specific disease at a given point in time.

Polygenic traits

Traits whose phenotypic variations are caused by the combined effects of multiple genes.

Multifactorial traits

Traits whose variations result from complex interactions between multiple genetic factors and environmental factors.

Empirical risks

Recurrence risks for multifactorial diseases derived from direct observation of clinical and population data.

Concordant trait

A trait shared by both members of a twin pair.

Discordant trait

A trait present in one member of a twin pair but absent in the other.

Developmental plasticity

The degree to which an organism's development is contingent upon and shaped by its environmental conditions.

Nutrigenomics

The study of how nutrition interacts with individual genomic differences to influence phenotypic variability and disease risk.

Xenobiotic chemicals

Toxic, mutagenic, and carcinogenic chemicals found in food that undergo activation by phase I enzymes like cytochrome P-450.

Glutathione-S-transferases (GSTs)

Phase II detoxification enzymes in the liver that metabolize environmental carcinogens and reactive oxygen species to protect against cancer.