CANCER

• Cells reproduce in defiance of restraints
• Cells invade and colonize territories reserved for other cells

Benign tumors

Reproduce without restraint but are noninvasive

Malignant tumors

Reproduce and metastasize

Proto-oncogene

Gene whose protein product stimulates normal cell growth and division

Oncogene

Mutated gene that has hyperactive function that can lead to cancer

Tumor suppressor gene

Gene whose protein product inhibits cell division and whose mutation can lead to cancer if it leads to decreased function

4 TYPES OF CANCER CAUSING MUTATIONS

Proto-oncogene

1. Gene moves to new location

• Could lead to excess protein production

2. Gene is duplicated

• Could lead to excess protein production

3. Mutation in gene’s control element

• Could lead to excess protein production

4. Mutation in gene itself

• Could lead to hyperactive or degradation resistant protein

MULTISTEP MODEL OF CANCER DEVELOPMENT

• Cancer is caused by an accumulation of mutations, not just one

Example: colon cancer pathway

1. Loss of tumor suppressor function (adenomatous polyposis coli gene)

• Can lead to a polyp (benign growth)

2. Activation of ras oncogene and
3. Loss of another tumor suppressor gene

• Can lead to an adenoma (larger benign growth)

4. Loss of p53 tumor suppressor and
5. Addition mutations that allow for invasion and metastasis

• Can lead to carcinoma (malignant tumor)