Transcript Cell Death and Cancer

The Cell Cycle and Cancer
Some thoughts about cell division…
• Do all cells divide at the same speed?
• What factors affect mitosis?
• How do cells die?
How do Cells Die?
Necrosis
Apoptosis
• Premature cell death
due to unexpected and
accidental cell damage.
• This is an unregulated
cell death.
• Causes: toxins,
radiation, trauma, lack
of oxygen due to the
blockage of blood flow.
• A cell also dies as a normal
part of the functioning of
healthy multicellular
organisms.
• This is a regulated or
controlled cell death of cells
that are no longer useful.
• Removes cells that have lost
their ability to perform
efficiently.
• The material of the cell is
recycled by the body.
What happens when
damage to a cell
impairs its ability to
commit apoptosis and
it starts to divides
uncontrollably?
Answer: Cancer
Cancer
• Uncontrolled cell division
• Caused by changes in the DNA
instructions controlling cell
division
• Loss of a cell’s ability to undergo
apoptosis (becomes “immortal”)
– On/off switch is broken
– Continually reproducing
Can lead to formation of a
lump or tumour. A tumour is
a mass of cells that continue
to divide without any benefit
to the body.
Normal Cells vs Cancer Cells
• In small groups (5-7 minutes)
– Compare Normal Cells to Cancer Cells
– Come up with similarities and differences
– Record on whiteboards
Normal Cells
Cancer Cells
Make exact copies of themselves
through mitosis
Make exact copies of themselves
through mitosis
Certain appearance.
Variability in appearance.
Reproduce for certain number of
controlled cell divisions (on-off
switch functional)
Uncontrolled cell division (on-off
switch NOT functional).
Normal cells respond to signals from Do not interact with other cells or
nearby cells (cell communication).
respond to signals. Behave
independently.
Stick together to form masses of
cells as appropriate.
Do not stick to other cells. Can
spread to other parts of the body.
Self-destruct when too old or too
damaged (apoptosis)
Grows into tumours. Cell death can
be via forced medical technologies
(eg. Chemotherapy, radiation, etc)
Cell Cycle Checkpoints
• Checkpoints are where the
cell assesses if conditions
are favorable for cell
division.
• When the environment is
not favorable (eg. Lack of
nutrients, damage to cell’s
DNA), a protein called p53
can stop the cell cycle and
cause the cell to die.
• When the proteins that
regulate the cell cycle are
mutated or absent, cells can
divide uncontrollably,
leading to cancer.
Tumours
• Tumours need nutrients and O2 to survive and to go
through the cell cycle. Therefore, they need access to the
body’s blood supply.
• Send out chemical signals to normal cells in surrounding
area and these normal cells encourage the blood vessels
to expand into the tumour mass.
Types of Tumours
Benign Tumours
• Harmless masses of cells
• Localized to a specific area –
does not interfere with
surrounding cells
Malignant Tumours
• Cancerous masses of cells
• Interferes with the work of
surrounding cells or
destroys those cells.
• These cells can break away
and spread to other parts of
the body and start a new
tumour (metastasis)
Causes of Cancer
Mutagens
• Random changes that can occur
when DNA is replicated; can be
genetically inherited
Carcinogens
• Any environmental factor that
can cause a mutation
– Tobacco products
– X-ray exposure
– UV radiation from sun or
tanning beds
– Viruses (eg. HPV)
– Certain toxic chemicals (eg. BPA
or PVC in plastics)
– Poor lifestyle choices (eg. Poor
diets can reduce amount of
cancer-fighting antioxidants in
your body)
Cancer Video: TED.com
“How do cancer cells behave differently from
healthy ones?” (George Zaidan)
• https://www.youtube.com/watch?v=BmFEoCF
Di-w
Cancer Screening
• Screening is an early detection tool that improves
chances of treatment and survival rates in most
cases.
• Can be done by yourself, your family doctor or a
specialist.
• Examples:
–
–
–
–
Breast self-exams
PAP smears (to check for signs of cervical cancer)
Testicular exams
Blood tests for increased PSA (prostate-specific
antigen) levels for prostate cancer.
Cancer Diagnosis
• Signs of cancer can include increased fatigue,
unexplained weight loss, swelling/pain in the
tumour area or can go undetected.
• Examples of technologies:
– Endoscopy (insertion of a viewing instrument into
body)
– X-ray
– Ultrasound (using sound waves to detect tumours)
– CT/CAT scan and MRI
– Sample removal/biopsies for microscopic examination
Cancer Treatment Options
•
•
•
•
•
•
Chemotherapy
Radiation therapy
Surgery
Biophotonics
Clinical drug trials
Holistic
Whiteboard
information:
•What is it? How
does it work? (Brief)
•2 pro’s
•2 con’s
1-1.5 minute
presentation