Transcript
When good cells go bad
The Cell Cycle and Cancer
What is cancer?Caner is defined as the continuous
uncontrolled growth of cells .A tumor is a an abnormal proliferation of
cells.Benign tumors stays confined to its original
locationMalignant tumors are capable of invading
surrounding tissue or invading the entire bodyTumors are classified as to their cell typeTumors can arise from any cell type in the
body
This video shows what the cancer is
Animation: How Cells Reproduce (cancer)
Normal and Cancer cells
1. Click on picture for cell cycle animation – will go to www.cancerquest.org)2. Use alt-tab keys to go between website and power point presentation. 3. Click on blank space to proceed to next slide.)
Cancer continued; three cancer types Carcinomas; constitute 90% of cancers,
are cancers of epithelial cellsSarcomas; are rare and consist of tumors
of connective tissues (connective tissue, muscle, bone etc.)
Leukemias and lymphomas; constitute 8% of tumors. Sometimes referred to as liquid
tumors. Leukemias arise from blood forming cells and lymphomas arise from
cells of the immune system (T and B cells).
Some Major Types of Cancer
In general, a cancer is named according to the type of tissue in which it first forms
Sarcomas: cancer of connective tissue
Carcinomas: cancer arising from epithelium
Lymphomas: cancer of lymphoid tissue
Leukemias: cancer of stem cells
Gliomas: cancer of brain cells
Cancer is a disease of the cell cycle. Some of the body’s cells divide uncontrollably and tumors form .
Tumors in LiverTumor in Colon
While normal cells will stop dividing if there is a mutation in the DNA, cancer cells will continue to divide with mutation.
Due to DNA mutations, cancer cells ignore the chemical signals that start and stop the cell cycle.
2 animations of cancer cells dividing: click on picture
Normal cells show contact inhibition
Cancer cells lack contact inhibition
They keep growing
And growing
And growing
And growing
Cancer Spreads Step-by-Step
This Cancer Cell Is Surrounded by White Blood Cells
4Cell
division
Mitosis
3DNA
repair
G21
Cell grows, doubles in
sizeG1
S
2Chromosome duplication
G1/S checkpoint
p. 183
Outside cell
Receptor
Plasma membrane
Cytoplasm
Nucleus
Changes in gene expression
Signal molecule
Signal–receptor binding
Cellular response
Protein molecules
Stepped Art
• Benign: localized and of small size
• Cells that closely resemble, and may function, like normal cells
• May be delineated by a fibrous (Basal lamina) capsule
• Become problems due to sheer bulk or due to secretions (e.g. hormones)
Normal Moles Are Common Examples of Benign Growths
Malignant tumors: high rate of division, properties may vary compared to cells of origin. Most malignant cells become metastatic
Invade surrounding tissue and establishment of secondary areas of growth: Metastasis
Cancer : Malignant
Main Features of Benign and Malignant Tumors
SmokingNumber one factor in cancer, either direct
(smoker) or indirect (secondhand smoke) -Related to cancers of oral cavity, larynx,
esophagus, and lungsAccounts for 30% of all cancer deathsMost have very low survival rate (e.g. 13% lung
cancer sufferers survive beyond 5 yrs
Lungs of Non-Smoker and Smoker
Other Factors Also May Lead to Cancer
Chemical carcinogensCarcinogens: cancer-causing substances
that can lead to a mutation in DNAAsbestos, vinyl chloride, and benzeneHydrocarbons in cigarette smokeAflatoxin: fungal product
RadiationUV from the sun and tanning lampsX-rays: medical and dentalRadon, cosmic rays, and gamma radiation
X-rays
Skin Cancer (1)~1 million new cases in U.S. per year
Almost all cases related to UV light exposure from sun or tanning lamps
Increasing, may be due to outdoor recreation or moving to regions with more sun exposure
Lightly pigmented people higher risk, genetic characteristics can affect the susceptibility
Melanoma
Other Factors Also May Lead to Cancer
Chemical carcinogensCarcinogens: cancer-causing substances
that can lead to a mutation in DNAAsbestos, vinyl chloride, and benzeneHydrocarbons in cigarette smokeAflatoxin: fungal product
RadiationUV from the sun and tanning lampsX-rays: medical and dentalRadon, cosmic rays, and gamma radiation
Some Industrial Chemicals Linked to Cancer
Biopsy Is the Only Sure Way to Diagnose Cancer
BiopsyRemoval and microscopic examination of tissue
Seven common cancer signs: CAUTION
Cancer Treatment and Prevention
When a person is diagnosed with cancer, a variety of weapons are available to combat it
Chemotherapy drugs
Radiation therapy
Surgery
Chemotherapy and Radiation Kill Cancer Cells
Radiation therapyUsed when cancer is small or
has not spreadRadioisotopes used, e.g., Ra-
226 and Co-60
Chemotherapy and radiation destroy healthy cells
More precise treatmentsMonoclonal antibody treatmentInterferon treatment; limited at
present
Good Lifestyle Choices Can Limit Cancer Risk
Avoid tobacco completely
Maintain a desirable weight; eat a low-fat diet with plenty of fruits and vegetables
Make sure your living and work environment is safe from carcinogens
Protect your skin from the sun’s UV rays
.
SUMMARYNormal Cell Division
.1DNA is replicated properly.
2 .Chemical signals start and stop the
cell cycle.3 .Cells communicate
with each other so they don’t become
overcrowded.
Cancer Cells
.1Mutations occur in the DNA when it is
replicated.2 .Chemical signals that
start and stop the cell cycle are ignored.
3 .Cells do not communicate with
each other and tumors form.
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