Ch 19 - Cancer Flashcards
What is differentiation? How does this relate to cancer?
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.
Why do cancer cells have large nuclei?
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
What is apoptosis, and how does that relate to cancer abnormalities?
In a normal cell, defective DNA undergoes apoptosis, or cell death. But cancer cells don’t
Which tissues are likely to develop cancer and why?
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
How does cell division differ in cancer cells?
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.
What role do telomeres and telomerase play in the lifetime of a cancer cell?
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
What is contact inhibition?
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
How do cancer cells react to stimulatory growth factors and inhibitory growth factors?
They’ll keep on dividing when stimulatory GFs are absent, and they don’t respond to inhibitory GFs
What is carcinogenesis, and what is the process?
carcinogenesis = the development of cancer
- initiation
- promotion
- progression
What happens during initiation?
a single cell undergoes a mutation that causes it to divide repeatedly
What happens during promotion?
a tumor develops. cells continue to divide and mutate
What happens during progression?
as cells keep mutating, eventually there’s a cell that has the ability to invade surrounding tissues
What is angiogenesis, and why does this occur in tumors?
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
How do cancers metastacize?
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)
What enzyme helps cancers invade basement membranes of tissues?
proteinase enzymes
What are checkpoints?
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
What happens when checkpoint proteins mutate?
the cell loses control of the cell cycle, resulting in cancer
What are proto-oncogenes? What happens when they mutate?
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.
What are tumor suppressor genes? What happens when they mutate?
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
What is Bax and what happens when it mutates?
a tumor suppressor. Bax is a protein that promotes apoptosis. When it’s mutated, apoptosis is less likely to occur
What is p53? Do tumors have this?
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
What is the BRCA1 gene, and what happens when it’s mutated?
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.
How many Americans will deal with cancer in their lifetime?
1 in 3
What is oncology?
the study of cancer
What is a prognosis? What does a patient’s prognosis depend on?
The probable outcome (of cancer). Depends on:
- whether the tumor has invaded surrounding tissues
- whether there are metastatic tumors in distant parts of the body
What are carcinomas?
Cancers in the:
- skin
- breast
- liver
- pancreas
- intestines
- lungs
- prostate
- thryoid
What are sarcomas?
Cancers in the:
- muscles
- connective tissues (bones + fibrous connective tissue)
What is leukemia?
Cancer in the:
- blood
What are lymphomas?
Cancers in the:
- lymphatic tissues
What are blastomas?
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)
What are the most common types of cancer?
- skin cancers
1. lung cancer
2. breast cancer
3. prostate cancer
4. colon/rectum cancer
What is Hodgkin vs. non-Hodgkin lymphoma?
Hodgkin develops from mutated B cells
non-Hodgkin develops from B cells or T cells
What’s the most common type of tumor in the endocrine system?
thyroid cancer
What happens if a mutated copy of the BRCA1 or BRCA2 gene is inherited from either parent?
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
What other gene requires a 2nd mutation before cancer arises?
The RB gene, another tumor suppressor gene, that can cause retinoblastoma, a rare eye disease, if mutation occurs on both copies
Which abnormal gene predisposes an individual to thyroid cancer?
RET, a proto-oncogene. only one mutation is needed to increase PREdisposition
What is a carcinogen? A mutagen?
mutagen = agent that causes mutations carcinogen = a chemical that causes cancer because it causes mutations to occur
What are examples of carcinogens?
- ionizing radiation (radon, nuclear fuel, x-rays, etc.)
What’s the 2nd leading cause of lung cancer in the US?
Radon
Why does tobacco cause cancer?
it contains a number of organic chemicals that are known mutagens (cause mutations)
What types of pollutants cause cancer?
metals, dust, chemicals or pesticides
What are the four types of DNA viruses that are directly believed to cause cancer?
Hep B (all chinese are affected, causing liver cancer)
Hep C
Epstein-Barr virus (all african children affected, causing burkitt lymphoma)
HPV (cervical cancer)
What warning signs should you look for to detect cancer?
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
What percentage of deaths from cervical cancer are prevented by getting regular Pap smears?
90%
What’s a colonoscopy?
examination of the entire colon
What’s a mammogram?
an x-ray study of the breast
What a CAT scan?
uses computer analysis of scanning x-ray images to create cross-sectional pictures that portray a tumor’s size and location.
What’s an MRI?
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
What’s an ultrasound?
Can confirm tumors of the stomach, prostate, pancreas, kidney, uterus and ovary
What’s a biopsy?
removal of a few cells for examination
What are tumor marker tests?
blood tests for antigens and/or antibodies. tumors release substances that provoke antibody responses
What can genetic tests do?
They can tell you if you have genetic mutations in proto-oncogenes and/or tumor suppressor genes
What are standard therapies for cancer?
- Surgery
- Radiation therapy = localized therapy
- Chemotherapy = therapy for cancer cells that have spread throughout the body
What are the types of chemotherapy medications?
- Alkylating agents = block replication of DNA
- Antimetabolites = block enzymes that cancer cells need
- Antihumor antibiotics = interfere w/ DNA, blocking enzymes and cell division + changes cell membranes
- Mitotic inhibitors = inhibit cell division or hinder certain enzymes necessary in cell repro. process
- Nitrosoureas = impede enzymes that help repair DNA
What is paclitaxel (Taxol)?
extract from a Pacific yew tree that is effective against advanced ovarian cancers, as well as head, breast and neck tumors
What types of cancers are treated with a combination of chemotherapy alone?
leukemias
lymphomas
testicular cancer
Why does chemo sometimes fail?
cancer cells become resistant to one or several chemotherapy drugs, called multi-drug resistance
How are bone marrow transplants used along with chemo?
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
How could p53 gene be used as therapy?
gene is only needed for 19 hrs to trigger apoptosis. seems to trigger cell death only in cancer cells
How could antiangiogenic drugs confine and reduce tumors?
by breaking up the network of new capillaries in the vicinity of a tumor
