Ch 19 - Cancer

Question 1

What is differentiation? How does this relate to cancer?

Answer 1

the process of cellular development by which a cell acquires a specific structure and function (i.e. red blood cells).

Cancer cells don’t look like other cells in the body, and they don’t contribute to the functioning of a body part.

Question 2

Why do cancer cells have large nuclei?

Answer 2

Because they contain an abnormal number of defective chromosomes (portions of chrom.s can be deleted or duplicated). the nuclei can take up almost the entire cell

Question 3

What is apoptosis, and how does that relate to cancer abnormalities?

Answer 3

In a normal cell, defective DNA undergoes apoptosis, or cell death. But cancer cells don’t

Question 4

Which tissues are likely to develop cancer and why?

Answer 4

Tissues that divide frequently, such as those that line the respiratory and digestive tracts. this is because each time they divide, there’s a chance for genetic mutation

Question 5

How does cell division differ in cancer cells?

Answer 5

In normal cells, cell division occurs 60-70 times before apoptosis occurs. Cancer cells are immortal and will continue dividing without ever experiencing cell death.

Question 6

What role do telomeres and telomerase play in the lifetime of a cancer cell?

Answer 6

telomeres = ends of chromosomes that contain special repetitive DNA sequences. in a normal cell, the telomeres get shorter after each cell cycle.

cancer cells contain an enzyme called telomerase that replenishes and rebuilds telomere sequences. this prevents the cancer cell from losing its potential to divide

Question 7

What is contact inhibition?

Answer 7

normal cells exhibit this, where they’ll come into contact with other cell neighbors, and this prevents them from dividing further.

cancer cells don’t have this inhibition. they’ll continue dividing, and pile one on top of the other, which creates tumors

Question 8

How do cancer cells react to stimulatory growth factors and inhibitory growth factors?

Answer 8

They’ll keep on dividing when stimulatory GFs are absent, and they don’t respond to inhibitory GFs

Question 9

What is carcinogenesis, and what is the process?

Answer 9

carcinogenesis = the development of cancer

1. initiation
2. promotion
3. progression

Question 10

What happens during initiation?

Answer 10

a single cell undergoes a mutation that causes it to divide repeatedly

Question 11

What happens during promotion?

Answer 11

a tumor develops. cells continue to divide and mutate

Question 12

What happens during progression?

Answer 12

as cells keep mutating, eventually there’s a cell that has the ability to invade surrounding tissues

Question 13

What is angiogenesis, and why does this occur in tumors?

Answer 13

the formation of new blood vessels. the low oxygen level in the middle of tumors can turn on genes that code for angiogenic growth factors that diffuse into nearby tissues, causing vessels to form

Question 14

How do cancers metastacize?

Answer 14

cancer cells must make their way across a basement membrane and invade a blood vessel or lymphatic vessel that transports the cancer cells to other locations in the body. not many cancers achieve this ability (1 in 10,000)

Question 15

What enzyme helps cancers invade basement membranes of tissues?

Answer 15

proteinase enzymes

Question 16

What are checkpoints?

Answer 16

checkpoints in the cell cycle monitor the condition of the cell and regulate its ability to divide. normally a protein called cyclin directs the movement of a cell through the cell cycle (i.e. mitosis). there are other proteins that monitor the cell cycle too

Question 17

What happens when checkpoint proteins mutate?

Answer 17

the cell loses control of the cell cycle, resulting in cancer

Question 18

What are proto-oncogenes? What happens when they mutate?

Answer 18

genes that code for proteins that promote the cell cycle and prevent apoptosis. they accelerate the cell cycle

when they mutate, they become cancer-causing genes called oncogenes. ongogenes are like proto-oncogenes on crack, stimulating the cell cycle even further and causing cells to divide more rapidly.

Question 19

What are tumor suppressor genes? What happens when they mutate?

Answer 19

genes that code for proteins that inhibit the cell cycle and promote apoptosis. when these genes mutate, their products no longer inhibit the cell cycle nor promote apoptosis. tumor suppressor genes therefore lose their function. this is referred to as a recessive mutation

Question 20

What is Bax and what happens when it mutates?

Answer 20

a tumor suppressor. Bax is a protein that promotes apoptosis. When it’s mutated, apoptosis is less likely to occur

Question 21

What is p53? Do tumors have this?

Answer 21

a tumor suppressor protein that activates DNA repair enzymes and turns on genes that stop the cell cycle from proceeding. if repair is impossible, apoptosis occurs. tumors lack p53 activity

Question 22

What is the BRCA1 gene, and what happens when it’s mutated?

Answer 22

BRCA1 mutations are associated with BReast CAncer (BRCA).

a tumor suppressor. This gene codes for DNA repair enzyme that fixes breaks in DNA. mutations prevent body from recognizing DNA damage, so cells progress through the cell cycle unchecked.

Question 23

How many Americans will deal with cancer in their lifetime?

Answer 23

1 in 3

Question 24

What is oncology?

Answer 24

the study of cancer

Question 25

What is a prognosis? What does a patient’s prognosis depend on?

Answer 25

The probable outcome (of cancer). Depends on:

1. whether the tumor has invaded surrounding tissues
2. whether there are metastatic tumors in distant parts of the body

Question 26

What are carcinomas?

Answer 26

Cancers in the:

• skin
• breast
• liver
• pancreas
• intestines
• lungs
• prostate
• thryoid

Question 27

What are sarcomas?

Answer 27

Cancers in the:

• muscles
• connective tissues (bones + fibrous connective tissue)

Question 28

What is leukemia?

Answer 28

Cancer in the:

- blood

Question 29

What are lymphomas?

Answer 29

Cancers in the:

- lymphatic tissues

Question 30

What are blastomas?

Answer 30

Cancer of immature cells (recall that an embryo is composed of three layers: ectoderm, mesoderm, and endoderm. Blastoma cells resemble the cells in the primary germ layer. For example, a nephroblastoma has cells similar to mesoderm cells, because the kidney grows from the mesoderm)

Question 31

What are the most common types of cancer?

Answer 31

• skin cancers
  1. lung cancer
  2. breast cancer
  3. prostate cancer
  4. colon/rectum cancer

Question 32

What is Hodgkin vs. non-Hodgkin lymphoma?

Answer 32

Hodgkin develops from mutated B cells

non-Hodgkin develops from B cells or T cells

Question 33

What’s the most common type of tumor in the endocrine system?

Answer 33

thyroid cancer

Question 34

What happens if a mutated copy of the BRCA1 or BRCA2 gene is inherited from either parent?

Answer 34

nothing. we inherit two copies of every gene, one from each parent. with just one copy of the gene, you’re more susceptible to get breast cancer. but the second copy would need to mutate in order for you to have breast cancer

if the 2nd mutation occurs in the breast, you develop breast cancer. if the 2nd mutation develops in the ovaries, you develop ovarian cancer

Question 35

What other gene requires a 2nd mutation before cancer arises?

Answer 35

The RB gene, another tumor suppressor gene, that can cause retinoblastoma, a rare eye disease, if mutation occurs on both copies

Question 36

Which abnormal gene predisposes an individual to thyroid cancer?

Answer 36

RET, a proto-oncogene. only one mutation is needed to increase PREdisposition

Question 37

What is a carcinogen? A mutagen?

Answer 37

mutagen = agent that causes mutations
carcinogen = a chemical that causes cancer because it causes mutations to occur

Question 38

What are examples of carcinogens?

Answer 38

• ionizing radiation (radon, nuclear fuel, x-rays, etc.)

Question 39

What’s the 2nd leading cause of lung cancer in the US?

Answer 39

Radon

Question 40

Why does tobacco cause cancer?

Answer 40

it contains a number of organic chemicals that are known mutagens (cause mutations)

Question 41

What types of pollutants cause cancer?

Answer 41

metals, dust, chemicals or pesticides

Question 42

What are the four types of DNA viruses that are directly believed to cause cancer?

Answer 42

Hep B (all chinese are affected, causing liver cancer)
Hep C
Epstein-Barr virus (all african children affected, causing burkitt lymphoma)
HPV (cervical cancer)

Question 43

What warning signs should you look for to detect cancer?

Answer 43

CAUTION

C - change in bowel/bladder habit
A - a sore that doesn't heal
U - unusual bleeding/discharge
T - thickening or lump in breast
I - indigestion or difficulty swallowing
O - obvious change in wart/mole
N - nagging cough or hoarseness

Question 44

What percentage of deaths from cervical cancer are prevented by getting regular Pap smears?

Answer 44

90%

Question 45

What’s a colonoscopy?

Answer 45

examination of the entire colon

Question 46

What’s a mammogram?

Answer 46

an x-ray study of the breast

Question 47

What a CAT scan?

Answer 47

uses computer analysis of scanning x-ray images to create cross-sectional pictures that portray a tumor’s size and location.

Question 48

What’s an MRI?

Answer 48

a type of imaging technique that depends on computer analysis. particularly useful for analyzing tumors in tissues surrounded by bone, just as tumors of the brain or spinal cord

Question 49

What’s an ultrasound?

Answer 49

Can confirm tumors of the stomach, prostate, pancreas, kidney, uterus and ovary

Question 50

What’s a biopsy?

Answer 50

removal of a few cells for examination

Question 51

What are tumor marker tests?

Answer 51

blood tests for antigens and/or antibodies. tumors release substances that provoke antibody responses

Question 52

What can genetic tests do?

Answer 52

They can tell you if you have genetic mutations in proto-oncogenes and/or tumor suppressor genes

Question 53

What are standard therapies for cancer?

Answer 53

1. Surgery
2. Radiation therapy = localized therapy
3. Chemotherapy = therapy for cancer cells that have spread throughout the body

Question 54

What are the types of chemotherapy medications?

Answer 54

1. Alkylating agents = block replication of DNA
2. Antimetabolites = block enzymes that cancer cells need
3. Antihumor antibiotics = interfere w/ DNA, blocking enzymes and cell division + changes cell membranes
4. Mitotic inhibitors = inhibit cell division or hinder certain enzymes necessary in cell repro. process
5. Nitrosoureas = impede enzymes that help repair DNA

Question 55

What is paclitaxel (Taxol)?

Answer 55

extract from a Pacific yew tree that is effective against advanced ovarian cancers, as well as head, breast and neck tumors

Question 56

What types of cancers are treated with a combination of chemotherapy alone?

Answer 56

leukemias
lymphomas
testicular cancer

Question 57

Why does chemo sometimes fail?

Answer 57

cancer cells become resistant to one or several chemotherapy drugs, called multi-drug resistance

Question 58

How are bone marrow transplants used along with chemo?

Answer 58

a patient’s stem cells are harvested and stored before chemotherapy begins. the stored stem cells are then returned to the patient by injection after chemo takes place

Question 59

How could p53 gene be used as therapy?

Answer 59

gene is only needed for 19 hrs to trigger apoptosis. seems to trigger cell death only in cancer cells

Question 60

How could antiangiogenic drugs confine and reduce tumors?

Answer 60

by breaking up the network of new capillaries in the vicinity of a tumor