Lecture 32

Question 1

Define benign tumor

Answer 1

Tumor that remains localized

Question 2

Define malignant tumor

Answer 2

Tumor cells invade other tissues

Question 3

Define metastasis

Answer 3

Tumor cells induce secondary tumors

Question 4

Define oncogenes and proto-oncogenes

Answer 4

Oncogenes: mutated, dominant-acting stimulatory genes that cause cancer

Proto-oncogenes: responsible for basic cellular functions in normal cells; when mutated, they become oncogenes

Question 5

Define tumor suppressor genes

Answer 5

Mutated recessive-acting inhibitory genes that are inactive

Question 6

What is the singular key event in cancer progression?

Answer 6

Genomic instability; leads to mutations that activate all of the secondary hallmark events (2 mutations are typically required for cancer initiation)

Question 7

Why is cancer a “genetic” disease, but most cancers are not inherited?

Answer 7

It is a genetic disease because it is caused/initiated by mutations in genes that cause cells to become abnormal and proliferate uncontrollably; most cancers aren’t inherited because it usually takes 2 mutations (2 hit hypothesis) and that is not likely to be passed on directly to offspring

Question 8

What are the different roles of tumor suppressor genes and oncogenes in cancer initiation and progression?

Answer 8

Tumor suppressor genes inhibit cell proliferation and slow or stop tumor development and growth, but are inactive when mutated (have 2 mutations that will then cause cell proliferation), while oncogenes are genes that have been mutated to cause cancer and tumor development and proliferation and are dominant genes (only takes one mutation)

Bottom Line - oncogenes need a single hit to be activated but tumor suppressors need a double hit to be inactivated

Question 9

What is the role of environmental factors in cancer initiation and progression?

Answer 9

Some environmental factors include tobacco use, obesity, alcohol, and UV radiation;

Question 10

What is the role of epigenetics in cancer initiation and progression?

Answer 10

Epigenetic modifications can lead to cancer, such as methylation of key sites that contain genes that normally suppress tumor growth

Question 11

What is the role of chromosome instability (translocations) in cancer initiation and progression?

Answer 11

A reciprocal translocation between chromosomes 9 and 22 cause chronic myelogenous leukemia, while a reciprocal translocation between chromosomes 8 and 14 causes Burkitt lymphoma

Question 12

Define loss of heterozygosity

Answer 12

Gross chromosomal event that results in loss of the entire gene and the surrounding chromosomal region

Question 13

What is the normal function of p53 and what happens when it is mutated?

Answer 13

Regulates cell division, apoptosis, DNA repair, and other functions; leads to many types of cancers when mutated