Question | Answer |
Lecture 54 | Molecular Basis of Cancer I |
Characteristics of Cancer Cells: | unregulated proliferation, invasion of surrounding normal tissues, and metastasis to more distant parts of body |
Tumor | Any abnormal proliferation of cells, may be benign or malignant |
Benign Tumor | Remains confined to its original location |
Malignant Tumor | Capable of invading surrounding normal tissue or spreading through body by circulatory/lymphatic system |
Only ___ tumors are proper cancers. | malignant |
Carcinomas | Cancer of epithelial cells |
Sarcomas | Cancer of connective tissue and muscle cells |
Leukemia/Lymphoma | Cancer of blood forming cells and cells of the immune system |
Glioma/Retinoblastoma | Cancer of central nervous system and eye |
Cancers have characteristics that reflect their ___. | origin |
___ tumors make up the majority of human tumors. | Epithelial |
Beneath the epithelial cell layer is the ___. | basement membrane (basal lamina); |
Beneath the basement membrane is the ___. | stroma |
Most common human cancers are ___. | carcinomas |
Carcinomas are responsible for >___% of cancer-related deaths in the western world. | >80% |
___ carcinomas arise from protective epithelial cells. | Squamous cell |
Adenocarcinomas arise from specialized epithelial cells that ___. | secrete |
Common squamous cell carcinomas: | skin, cervix, lung |
Common adenocarcinomas: | lung, colon, breast, pancrease, prostate, ovary |
Sarcomas derive from various cell types, including: | fibroblasts, adipocytes, osteoblasts, and myocytes |
Sarcomas account for ___% of tumors encountered in clinics. | 1% |
Leukemia | Malignant derivatives of blood forming cell lineages, moves freely through blood circulation |
Lymphomas | Tumors of lymphoid lineages (B-/T-lymphocytes), aggregate to form solid masses, commonly in lymph nodes |
Neuroectodermal tumors arise from from components in the: | central and peripheral nervous system |
Neuroectodermal tumors compose ___% of all diagnosed cancers, and is responsible for ___% of cancer-related deaths. | 1.3%, 2.5% |
Most cancers derive from: | a single abnormal cell |
Evidence of single-cell origin derived from: | same chromosomal abnormality, same X chromosome inactivated, production of same antibody from malignant B-lymphocytes |
Development of cancer is a ___ process, where the cells gradually become malignant. | multistep |
Tumor development involves selection of cells with increased capacity for ___, ___, ___, and ___. | proliferation, survival, invasion, and metastasis. |
Carcinogens | Agents that can cause cancer |
Chemical carcinogens act by: | damaging DNA and introducing mutations |
___, ___, and ___ are carcinogens in tobacco smoke, causing 80-90% of lung cancers. | Benzopyrene, dimethylnitrosamine, and nickel compounds |
Ionizing radiation causdes: | DNA breaks and cross-linking between DNA (introducing mutations) |
Some viruses introduce ___that can cause cancer. | foreign DNA |
___ and ___ virus can liver cancer and cervical cancer, respectively. | Hepatitis and papilloma |
Ames Test | Asses mutagenic properties of compounds with homogenized rat liver, counts bacterial colonies to determine carcinogenic properties |
Some carcinogens contribute to cancer progression by stimulating cell ___ (instead of introducing mutations). | proliferation (i.e. hormones likes estrogen) |
Cancer results from mutations in genes controlling ___. | cell proliferation |
Two mutational routes for uncontrolled cell proliferation are: | proto-oncogene/oncogene and tumor suppressor gene |
Oncogene mutation has a dominant effect, requiring: | only 1 copy to be mutated |
Tumor suppressor gene has a recessive effect, requiring: | both copies to be mutated |
Most retroviruses contain only three genes: | gag, pol, and env |
Gag, pol, and env do not induce: | cell transformation |
Retroviruses that cause cancer have acquired ___. | oncogenes |
Retroviruses pick up oncogenes by ___. | accident |
Any gene can be ___ into the retrovirus. | incorporated |
Incorporation of non-oncogenes into the retrovirus leads to: | nothing (generally) |
Most oncogenes encode for proteins that stimulate: | growth pathways |
Many growth factors promote proliferation of cells by inducing ___ expression. | cyclin D |
Oncogenes signal ___ in absence of extracellular cues. | proliferation |