click below
click below
Normal Size Small Size show me how
toxicology ch 8
| Question | Answer |
|---|---|
| Cancer | disease of cellular mutation, proliferation, & aberrant cell growth |
| Tumor | complex tissue w/ multiple cell populations that interact, function as a tissue |
| Benign | tissue of origin followed by suffix “oma” |
| Malignant | develop when abnormal cells grow, multiply, and spread to other parts of the body. |
| Carcinogen | Substance capable of causing cancer in living tissue |
| Genotoxic carcinogen | Interact physically w/ DNA to damage or change its structure |
| Nongenotoxic carcinogen | Changes how DNA expresses information w/o modifying or damaging its structure •Creates a situation that makes cell/tissue more susceptible to DNA damage |
| Carcinogenesis | Process of definable & reproducible stages |
| MULTISTAGE CARCINOGENESIS | 1.Initiation - mutation occurs 2.Promotion - mutated cells divide 3.Progression - more mutations, cells more aggressive |
| •Direct-acting (activation-independent) genotoxic carcinogens | interact physically w/ DNA, produces highly reactive electrophilics, frequently result in tumor formation at chemical exposure site |
| Indirect-acting genotoxic carcinogens | require metabolism to become carcinogenic |
| Mutagens | transitions, transversions, frame-shifting, or broken DNA |
| Polyaromatic hydrocarbons | cigarette smoke, BBQ, diesel exhaust |
| Alkylating agents | multiple drugs |
| Aromatic amines/amides | dyes, cigarette smoke |
| Cytotoxicity | produces cell turnover, chance of DNA mutation |
| •Receptor-mediated CAR | cell proliferation, inhibit apoptosis |
| PPARα | transcription factor, gene expression |
| AhR | transcription factor, links environmental chemical stimuli w/ adaptive responses (detoxification, cellular homeostasis, immune responses) |
| Hormonal | estrogen/TSH leads to cell proliferation |
| Altered methylation | affects gene translation |
| Oxidative stress | DNA breaks, crosslinks, other modifications |
| Proto-oncogenes, tumor-suppressor genes | regulate cell division |
| Retroviruses | mutate genes in nearly normal cells (HIV) |
| DNA viruses | most lethal to non-host animal cells; survivors permanently transformed (HPV) |
| SHORT-TERM TESTS FOR MUTAGENICITY | identify potential genotoxic carcinogens |
| In vitro gene mutation assay | Ames assay - uses his- bacteria Mouse lymphoma assay - uses eukaryotic cells Chinese hamster ovary (CHO) test - chromosomes |