View
3
Download
0
Category
Preview:
Citation preview
1
Chapter 20
Lecture Outline
See separate PowerPoint slides for all figures and tables pre-
inserted into PowerPoint without notes.
Copyright © 2016 McGraw-Hill Education. Permission required for reproduction or display.
3
Points to ponder • What are characteristics of cancer cells?
• What are the three stages in the development of cancer?
• What are angiogenesis and metastasis?
• How do proto-oncogene and tumor-suppressor genes normally act, and how can they become cancerous?
• Explain different types of cancer, depending on tissue type involved.
• What are some genetic and environmental causes of cancer?
• What does CAUTION stand for in regards to cancer?
4
Points to ponder
• What are some regular screening tests you can get to help prevent cancer?
• Know how to do self exams.
• What are tumor marker and genetic tests?
• What are some standard treatments for cancer?
• What are some newer cancer therapies?
• What is your opinion on controlling tobacco?
5
Characteristics of cancer cells
1. Lack differentiation and do not contribute to
body functioning
2. Have abnormal nuclei that are enlarged and
may have an abnormal number of
chromosomes
3. Unlimited ability to divide
• One way is through turning on the
telomerase gene that allows telomeres on
chromosomes to continually be built, thus
allowing a cell to divide over and over again.
20.1 Cancer Cells
6
Characteristics of cancer cells
4. Form tumors
• Benign tumors are usually encapsulated and
do not invade adjacent tissue, while a
cancerous tumor usually is not encapsulated
and eventually invades surrounding tissue.
5. Can divide without growth factors
6. Become abnormal gradually through a
multistage process
7. Undergo angiogenesis and metastasis
20.1 Cancer Cells
7
3 phases in the development of
cancer cells
• Initiation – a single cell undergoes a mutation
that causes it to divide repeatedly
• Promotion – a tumor develops and cells within
the tumor mutate
• Progression – a cell mutates in such a way
that allows it to invade surrounding tissue
20.1 Cancer Cells
8
3 phases in the development of
cancer cells
Figure 20.2 Progression from a
single mutation to a tumor.
20.1 Cancer Cells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
distant tumor
e. Cancer cells now have the ability to invade lymphatic and blood vessels.
d. Cells have gained the ability to invade underlying tissues by producing a proteinase enzyme.
malignant tumor
invasive tumor
blood vessel
lymphatic vessel
3 mutations
tumor
2 mutations
1 mutation epithelial cells
a. Cell (dark pink) acquires a mutation for repeated cell division.
b. New mutations arise, and one cell (brown) has the ability to start a tumor.
c. Cancer insitu. The tumor is at its place of origin .One cell (purple) mutates further.
f. New metastatic tumors are found some distance from the original tumor.
lymphatic vessel
9
What are angiogenesis and metastasis?
• Angiogenesis is the formation of new blood
vessels to supply nutrients and oxygen to the
tumor.
• Metastasis occurs when cells move into the
bloodstream or lymphatic vessels and form new
tumors at distant sites from the primary tumor.
20.1 Cancer Cells
10
The genetic basis for cancer
• Proto-oncogenes – products promote the cell cycle and prevent cell death (apoptosis)
• Tumor suppressor genes – products inhibit the cell cycle and promote apoptosis
• Mutations in these genes can cause cancer; in fact, proto-oncogenes that have mutated are cancer-causing genes called oncogenes.
20.1 Cancer Cells
11
Mutations in proto-oncogenes produce
oncogenes that stimulate the cell cycle
Figure 20.3 Mutations in proto-oncogenes produce oncogenes that stimulate the cell cycle.
20.1 Cancer Cells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
receptor
cytoplasm
transcription factor
stimulating growth factor
plasma
membrane
signaling
pathway
protein that
over stimulates
the cell cycle
nucleus
oncogene
12
Mutations in tumor suppressor genes
cause a loss of cell cycle control
Figure 20.4 Mutations in tumor suppressor genes cause a loss of cell cycle control.
20.1 Cancer Cells
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
receptor
cytoplasm
transcription factor
inhibiting growth factor
plasma
membrane
signaling
pathway
nucleus
protein that
unable to inhibit
the cell cycle
or promote
apoptosis
mutated tumor suppressor gene
13
Types of cancer
• Oncology is the study of cancer.
• Carcinomas: cancers of the epithelial tissue
• Adenocarcinomas: cancers of glandular
epithelial cells
• Sarcomas: cancers of muscle and connective
tissues
• Leukemias: cancers of the blood
• Lymphomas: cancers of lymphatic tissues
20.1 Cancer Cells
14
Causes of cancer
• Genetics
• Environmental carcinogens
– Radiation
– Environmental carcinogens (tobacco smoke
and pollutants)
– Viruses
20.2 Causes and Prevention of Cancer
15
Estimated cases of cancer and
cancer deaths in the United States
Figure 20.5 Estimated cases of cancer and cancer deaths in the United States.
20.2 Causes and Prevention of Cancer
16
Genetic causes of cancer
• Examples of genes associated with cancer
– BRCA1 and BRCA2 are tumor suppressor genes that are associated with breast cancer.
– RB is a tumor suppressor gene that is associated with an eye tumor.
– RET is a proto-oncogene that is associated with thyroid cancer.
• Mutations of these genes predispose individuals to certain cancers but it takes at least one more acquired mutation during their lifetime to develop cancer.
20.2 Causes and Prevention of Cancer
17
Transposons
• Transposons (“jumping genes”) are small,
mobile sequences of DNA that have the
ability to move throughout the genome,
sometimes causing mutations.
• If a transposon causes a loss of cell cycle
control, it can cause cancer.
20.2 Causes and Prevention of Cancer
18
Environmental causes of cancer
• Radiation
– Environmental factors such as UV light (in sunlight or tanning lights) and X-rays can cause mutations.
• Organic chemicals – Tobacco smoke increases cancer of lungs,
mouth, larynx, and others.
– Pollutants such as metals, dust, chemicals, and pesticides increase the risk of cancer.
20.2 Causes and Prevention of Cancer
19
Environmental causes of cancer
• Viruses – Hepatitis B and C viruses can cause liver
cancer.
– Epstein-Barr virus can cause Burkitt lymphoma.
– Human papillomavirus can cause cervical cancer.
– HTLV-1 (human T-cell lymphotropic virus, type 1) can cause hairy cell leukemia.
– HIV and Kaposi’s sarcoma, associated herpesvirus (KSHV), can cause Kaposi’s sarcoma and certain lymphomas.
20.2 Causes and Prevention of Cancer
20
7 warning signs of cancer
• Change in bowel or bladder habits
• A sore that does not heal
• Unusual bleeding or discharge
• Thickening or lump in breast or elsewhere
• Indigestion or difficulty in swallowing
• Obvious change in wart or mole
• Nagging cough or hoarseness
20.3 Diagnosis of Cancer
21
Detecting skin cancer
• A – asymmetry
• B – border is
irregular
• C – color varies
from one area to
another
• D – diameter is
larger than 6 mm
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
A= Asymmetry : One-
half of mole does
not look like the
other half
B= Border: Irregular
scalloped or poorly
circumscribed border
C= Color: Varied from
one are a to another;
shades of tan, brown,
black, or sometimes
white, red, or blue
D= Diameter: Larger
than 6mm (the
diameter of a
pencil eraser)
E= Elevated: Above
skin surface, and
evolving, or changing
overtime
A: © Custom Medical Stock Photo, Inc.; B: © ISM/Phototake; C: © Dr. P. Marazzi/Photo Researchers, Inc.;
D: © Custom Medical Stock Photo, Inc.; E: © Dr. Ken Greer/VisualsUnlimited
Figure 20.8 The ABCDE test for melanoma.
20.3 Diagnosis of Cancer
22
Some routine screening tests for cancer
• Self-examination – monthly exams of breasts and testicles starting at age 20
• Colonoscopy – every five years starting at age 50
• Mammogram – yearly after age 40
• Pap test – should begin three years after vaginal intercourse or no later than age 21
Figure 20.9 Mammograms can detect breast cancer.
20.3 Diagnosis of Cancer
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
a. b. (both): © UHB Trust/Getty Images
23
Self exams
finger
pads
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Figure 20A Shower check for breast
cancer.
Figure 20B Mirror check for breast
cancer.
Figure 20C Shower check for
testicular cancer.
20.3 Diagnosis of Cancer
24
Other ways to detect cancer
• Tumor marker tests – blood tests for tumor antigens/antibodies – CEA (carcinoembryonic antigen) antigen
can be detected in someone with colon cancer
– PSA (prostate-specific antigen) test for prostate cancer
– AFP (alpha-fetoprotein) test for liver tumors
20.3 Diagnosis of Cancer
25
Other ways to detect cancer
• Genetic tests – tests for mutations in proto-oncogenes and tumor suppressor genes – RET gene (thyroid cancer)
– P16 gene (associated with melanoma)
– BRCA1 (breast cancer)
• A diagnosis of cancer can be confirmed by performing a biopsy.
20.3 Diagnosis of Cancer
26
Prevention of Cancer
• Protective behaviors
– Don’t use tobacco.
– Don’t sunbathe or use a tanning booth.
– Avoid radiation.
– Be tested for cancer.
– Be aware of occupational hazards.
– Be aware of postmenopausal hormone therapy.
– Get vaccinated.
20.3 Diagnosis of Cancer
27
Prevention of Cancer
• The right diet
– Avoid obesity.
– Eat plenty of high-fiber foods.
– Increase consumption of foods that are rich in vitamins A and C.
– Reduce consumption of salt-cured, smoked, or nitrite-cured foods.
– Include vegetables from the cabbage family in the diet.
– Drink alcohol in moderation.
20.3 Diagnosis of Cancer
28
Standard cancer treatments • Surgery – removal of small cancers
• Radiation therapy – localized therapy that causes chromosomal breakage and disrupts the cell cycle
• Chemotherapy – drugs that treat the whole body and kill cancer cells by damaging their DNA or interfering with DNA synthesis
• Bone marrow transplants – transplant bone marrow from one individual to another
20.4 Treatment of Cancer
29
Newer cancer therapies • Immunotherapy – inject immune cells that are genetically
engineered to bear the tumor’s antigens
• Passive immunotherapy – antibodies that are linked to radioactive isotopes or chemotherapeutic drugs are injected into the body
• p53 gene therapy – a retrovirus in clinical trial that is injected into the body where it will infect and kill only tumor cells (cells that lack p53 = tumor cells)
• Angiogenesis inhibition - angiostatin and endostatin are drugs in clinical trials that appear to inhibit angiogenesis
20.4 Treatment of Cancer
30
Immunotherapy
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
5. APCs present tumor
antigen to cytotoxic
T cells, and they attack
tumor cells. 4.Genetically engineered cells
are returned to patient.
gene for
tumor antigen
2. APCs are genetically
engineered to have genes
for tumor antigens.
cytokines
stimulate APCs tumor
cell
antigen
APC
1. Antigen-presenting cell
(APCs) are removed
from the patient.
3.APCs display tumor
antigens at their surface.
tumor antigen
cytotoxic
T cell
Figure 20.12 Use of immunotherapy to treat cancer.
20.4 Treatment of Cancer
Recommended