Chapter 25: Cancer genetics

clonal

All cells are descended from one another

cancer is ______ and involves multiple mutations beginning with a ________ change that if left untreated can morph into a malignant/invasive growth

clonal, benign

cancer

a genetic disease characterized by uncontrolled cell division

how many different kinds of human cancers are known

more than 100

how are cancer cells classified

According to the type of cell that has become cancerous

why are cancers considered to be clonal

because most cancers originate in a single cell

At the cellular and genetic levels cancer is usually a ________

multistep process

how does cancer begin, and then how does it progress

begins with a precancerous genetic change (benign growth), and following additional genetic changes, it progresses to cancerous cell growth

invasive cells

can invade healthy tissues

Once a cellular growth has become ________ the cells are ______

malignant, invasive

metastatic

cells that can migrate to other parts of the body

most cancers are the result of ________ mutations that accumulate in a single cell

multiple somatic

how many Americans are diagnosed with new cancers each year

1.5 million

How many people will die from cancer each year

about 500,000

are cancers likely to be associated with an inherited component

most cancers (90-95%) are not associated with an inherited component

what percentage of cancers have an inherited component

5-10%

what are most cancers related to

exposure to mutagens that alter the structure and expression of genes

What percentage of non-inherited cancers are the result of spontaneous mutations and viruses

less than 5%

carcinogens

specific compounds that are known to cause cancer

what are the most common cancers in the US

breast, prostate, lung, colon, and skin

Is cancer rates proportional to economic status

yes, rates are highest in countries with the highest life expectancy, education, and standard of living

prostate, lung, and colon make up what percetange of male cancers

48%

Breast, lung, and colon make up what percentage of female cancers

51%

proto-oncogene

A gene often found mutated in cancer, whose normal function is to regulate cell growth

oncogene

mutated form a normal gene that helps to promote or allows for the uncontrolled cell growth of cancer

what is the cell cycle regulated by in eukaryotes

polypeptide hormones known as growth factors

What are the four main ways of proto-oncogenes becoming oncogenes

missense mutations, gene amplifications, chromosomal translocations, and viral integration

is mutation in proto-oncogenes a gain or loss of function mutation

a gain-of-function mutation

what are the three ways that proto-oncogenes can become abnormally active

they may be overexpressed, they may be a product an aberrant protein, or they may be expressed in a cell type where they are not normally expressed

tumor-suppressor genes

a gene whose normal function is to regulate or slow the cell cycle. Cancer progresses by the loss of these genes or their function

what happens when tumor-suppressor genes are inactivated

when inactivated by mutation it becomes more likely that cancer will occur

what percentage of all human cancers are associated with defects in the p53 gene

50%

what is the primary role of the p53 protein

to determine if a cell has incurred DNA damage and if so will promote different cellular pathways to prevent the division of cells with damaged DNA

What are the three types of things that p53 can do

activate genes that promote DNA repair, activate genes that arrest cell division, and may generally repress other genes that are required for cell division, or activate genes that promote apoptosis

what can make a cancer more difficult to treat

A malignancy can continue to accumulate genetic changes that make it even more difficult to treat

what do most inherited forms of cancer involve

a defect in a tumor-suppressor gene

What kinds of cancer are there genetic testing for

familial adenomatous polyposis, and breast cancer