Ch 26 Cancer Cells

Carcinomas

a malignant tumor (cancer) arising from the epithelial cells that cover external and internal body surfaces.

Sarcomas

any cancer arising from a supporting tissue, such as bone, cartilage, fat, connective tissue, and muscle

Lymphomas

cancer of lymphatic origin in which the cancer cells grow as solid masses of tissue.

Tumor

cancer cells grow as solid masses of tissue.

Benign tumors

tumor that grows only locally, unable to invade neighboring tissues or spread to other parts of the body

Malignant tumors

tumor that can invade neighboring tissues and spread through the body via fluids, especially the bloodstream, to other parts of the body; also called a cancer.

Cancer

uncontrolled, growing mass of cells that is capable of invading neighboring tissues and spreading via body fluids, especially the bloodstream, to other parts of the body; also called a malignant tumor.

Anchorage-independent growth

a trait exhibited by cancer cells, which grow well not just when they are attached to a solid surface, but also when they are freely suspended in a liquid or semisolid medium.

Density-dependent inhibition of growth

tendency of cell division to stop when cells growing in culture reach a high population density.

Initiation

irreversible conversion of a cell to a precancerous state by agents that cause DNA mutation.

Promotion

gradual process by which cells previously exposed to an initiating carcinogen are subsequently converted into cancer cells by agents that stimulate cell proliferation.

Tumor progression

gradual changes in tumor properties observed over time as cancer cells acquire more aberrant traits and become increasingly aggressive

Angiogenesis

growth of new blood vessels.

Invasion

direct spread of cancer cells into neighboring tissues.

Metastasis

spread of tumor cells to distant organs via the bloodstream or other body fluids.

Carcinogens

any cancer-causing agent

Precarcinogens

substance capable of causing cancer only after it has been metabolically activated by enzymes in the liver.

Ames test

screening test for potential carcinogens that assesses whether a substance causes mutations in bacteria

Ionizing radiation

high-energy forms of radiation that remove electrons from molecules, thereby generating highly reactive ions that cause DNA damage; includes X-rays and radiation emitted by radioactive elements.

Ultraviolet radiation (UV)

mutagenic type of radiation present in sunlight that triggers the formation of pyrimidine dimers in DNA.

Oncogenic virus

virus that can cause cancer

Burkitt lymphoma

a lymphocyte cancer associated with infection by Epstein-Barr virus along with a chromosome translocation in which the MYC gene is activated by moving it from chromosome.

Epstein-Barr virus (EBV)

virus associated with Burkitt lymphoma (as well as the noncancerous condition infectious mononucleosis)

Oncogene

any gene whose presence can cause cancer; arises by mutation from normal cellular genes called proto-oncogenes

Proto-oncogenes

normal cellular gene that can be converted into an oncogene by point mutation, gene amplification, chromosomal translocation, local DNA rearrangement, or insertional mutagenesis

Tumor suppressor genes

gene whose loss or inactivation by deletion or mutation can lead to cancer.

Two-hit hypothesis

hypothesis that loss-of-function mutations in each of the two copies of a tumor suppressor gene are required to predispose cells to become cancerous

p53 gene

tumor suppressor gene that codes for the p53 protein, a transcription factor involved in preventing genetically damaged cells from proliferating; most frequently mutated gene in human cancers