Cancer as endpoint of chemical exposure Flashcards
(24 cards)
What is cancer characterized by?
Genomic mutation, modified gene expression, cell proliferation, and aberrant cell growth
Cancer is one of the leading causes of death globally.
Define neoplasia.
New growth or autonomous growth of tissue.
What are malignant neoplasms from epithelial origin called?
Carcinoma.
What is the term for substances that induce cancer?
Carcinogens.
Differentiate between genotoxic and nongenotoxic carcinogens.
Genotoxic carcinogens interact with DNA, while nongenotoxic carcinogens do not directly interact with DNA but may alter gene expression.
What are the three stages of carcinogenesis?
Initiation, promotion, and progression.
What occurs during the initiation stage of carcinogenesis?
A stable, heritable change due to a carcinogen-induced mutational event.
What are initiating agents in the context of carcinogenesis?
Chemical and physical agents that lead to genetic changes including mutations and deletions.
What are the two types of DNA-reactive carcinogens?
- Direct-acting (activation-independent)
- Indirect-acting (require metabolic activation)
What is the role of direct-acting carcinogens?
They directly bind to DNA without being metabolized.
What is a procarcinogen?
A parent compound that requires metabolism to become carcinogenic.
Define mutagenesis.
The process by which mutations occur in DNA.
Describe homologous recombination in DNA repair.
Repair of double-strand breaks using the information from a homologous, intact chromosome.
What are polycyclic aromatic hydrocarbons (PAHs)?
Carcinogens found in charcoal-broiled foods, cigarette smoke, and diesel exhaust.
What are Polyaromatic Hydrocarbons (PAHs)?
PAHs are found at high levels in charcoal-broiled foods, cigarette smoke, and in diesel exhaust.
PAHs are a class of chemicals that are known to be genotoxic carcinogens.
What is a characteristic of non-genotoxic carcinogens?
They often target organs and tissues with a high incidence of spontaneous tumors and require prolonged exposure to induce tumors.
Examples include chemicals that induce cytotoxicity or hormonal perturbations.
What is cytotoxicity in the context of carcinogenesis?
Cytotoxicity involves sustained cell death leading to regenerative growth and potential accumulation of DNA mutations.
This can result in preneoplastic lesions and tumor formation.
What are estrogenic agents?
Estrogenic agents are chemicals that can induce tumors in estrogen-dependent tissues, impacting hormonal balance.
Diethylstilbestrol (DES) is a notable example linked to increased cancer risk.
What impact does thyroid hormone have on carcinogenesis?
Reduced thyroid hormone and increased TSH can induce neoplasia in the thyroid gland.
TSH promotes cell proliferation, which can lead to tumor formation.
Which metals are known carcinogens?
Notable carcinogenic metals include arsenic, beryllium, cadmium, chromium, nickel, and lead.
Their carcinogenic effects can vary by type of exposure.
What does hormesis refer to in the context of dose-response?
U, J, or inverted U-shaped dose–response with low-dose exposures often resulting in beneficial effects
What organ is primarily tested for carcinogenicity due to its high incidence of cancer?
Liver
Nearly half of the chemicals tested in chronic bioassays show increased liver cancer incidence.
What does the IARC classification scheme assess?
The carcinogenicity of chemicals and mixtures
It categorizes agents based on strength of evidence for carcinogenicity.
What are the characteristics of cancer as a multistage process?
Increased selective lesion growth, angiogenesis, replicative immortality, invasion and metastasis, evasion of growth suppression, altered energy metabolism, immune system evasion
These characteristics involve multiple molecular and cellular events.
