Date post: | 07-Apr-2018 |
Category: |
Documents |
Upload: | rajesh-balakrishnan |
View: | 218 times |
Download: | 0 times |
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 1/28
The Cell Cycle and Cancer
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 2/28
Cell signaling: chemical
communication between cells.
Click on above to go to
animation
second chemical response inside the
cell. This may be the first step of an
entire chemical cascade of chemical
signals that trigger actions in the cell.
Achemical
signal to a
receptor
on theoutside of
a cell may
trigger a
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 3/28
Cancer � Normal cell division:
± Controlled by cell cycle checkpoints
� CHECKPOINTS ± critical control points that determine if a
cell will move to the next portion of the cell cycle.
� Cancerous cell division: ± Ignores the cell cycle checkpoints
� Caused by DNA mutations
� Cells grow and divide out of control
� Cancerous cells do not perform designated purpose.� Crowd out normal cells that do perform designated purpose.
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 4/28
The Stages of the Cell Cycle
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.)
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 5/28
There are several factors that regulate the
cell cycle and assure a cell divides correctly.
1.Before a cell divides,
the DNA is checked
to make sure it has
replicated correctly. (If
DNA does not copyitself correctly, a gene
mutation occurs.
DNA replication animation:click
on DNA picture
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 6/28
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 7/28
Cell Cycle Checkpoints
� G1/S ± Monitors cell size and for DNA damage
� G2/M
± Replication complete, DNA damage?
� M
± Spindle fibers connected, etc.?
� G0 ± Does body require more of my type of cell?
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 8/28
� Control of cellular division
± Genes code for proteins that either stimulate cell
growth or suppress it.
� Cyclins: proteins that control phases of the cell cycle.
± Examples:
» S-cycline stimulates DNA replication
» M-cycline helps trigger mitosis
� Growth factors supervise progress through the cycle.
± Sometimes trigger genes to make cyclins.
± Sometimes block cyclins
� Proto-oncogenes: genes involved in growth stimulation
± Mutation here can produce an ³onco-gene´ which triggersuncontrolled growth. GAS PEDAL
� Tumor suppressor genes: inhibit growth and division
± Mutation here = loss of inhibition BRAKE
» Cells divide out of control without normal functioning
suppressor gene
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 9/28
� Example of a
tumor suppressor
gene:
±p53 gene
codes for
apoptosis:
(Programmedcell death)
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 10/28
2. Chemical Signals tell a cell when to start
and stop dividing.
(Target cells animation: click on go
sign)
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 11/28
Control of cell division continued:
Density Dependent Inhibition: Normal cells cease
dividing once critical cell density is reached. Cancer
cells do not possess this trait.
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 12/28
Neighboring cells communicate with dividing
cells to regulate growth.
(Normal contact inhibition animation: click on petri dish)
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 13/28
� Anchorage dependence:
proteins located in plasmamembrane indicate
attachment to neighboring
cells/tissue
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 14/28
DNA mutations disrupt the cell cycle.
Carcinogens:
1. radiation
2. smoking3. Pollutants
4. chemicals
5. viruses
6. Heredity
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 15/28
What causes the mutations thatlead to cancer?
� Viruses: HPV --> cervical cancer ± Bacteria: H. pylori --> gastric cancer (bacteria usually not a
known carcinogen)
� Chemicals --> lung cancer � UV radiation --> skin cancer
� What do these agents have in common?
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 16/28
u s ep rocess: ancer resu s rom
³multiple hits´
� Cancer requires mutation of multiple genes� Age relationship:
± Cancer rate increases dramatically with age.
� Delay between carcinogen exposure andonset
± 5-8 year delay between carcinogen exposure
(Hiroshima and Nagasaki) and onset of
leukemia ± 15 year delay between tuberculosis X-ray
treatment and onset of breast cancer
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 17/28
Age and Cancer
� Note log scale for
incidence rate
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 18/28
Cancer is a disease of the cell cycle. Some
of the body¶s cells divide uncontrollably and
tumors form.
Tumors in Liver
Tumor in Colon
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 19/28
While normal cells will stop dividing if there is a mutation in
the DNA, cancer cells will continue to divide with mutation.
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 20/28
Due to DNA mutations, cancer cells ignore the
chemical signals that start and stop the cell cycle.
They don¶t communicate with neighboring cells
and continue to grow and form tumors.
2 animations of cancer cells dividing: click on picture
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 21/28
SUMMARYNormal Cell Division
1. DNA is replicated
properly.
2. Chemical checkpoints
signal start and stopof the cell cycle.
3. Cells communicate
with each other so
they don¶t becomeovercrowded.
Cancer Cells
1. Mutations occur in the DNA
2. Ignores normal checkpoints
= excessive division
3. Unusual # of chromosomes
4. Loss of attachment and
other control mechanisms
5. Immortality
6. Extensive angiogenesis
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 22/28
Normal and Cancer
Karyotypes
� (a) is a normal cell, (b) is a cancer cell
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 23/28
Benign or malignant?
� Benign tumors do notspread from their siteof origin, but cancrowd out
surrounding cells.
� Malignant tumors
can spread from theoriginal site andcause secondarytumors. This is called
metastasis.
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 24/28
� Metastasis: cells travelthrough blood vessels or
lymph to other areas of thebody and grow there. Thisis what makes tumors solethal.
� interfere with normalfunctioning of other tissues
vital to survival.
.
Pathways of cancer:
cell signaling
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 25/28
Treating Cancers
Cancer treatments include drugs that can stop
cancer cells from dividing.
Chemotherapy:
Radiation:Surgery:
Other medications designed to assist the body in
preventing cancerous cell division.
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 26/28
Cancer therapies targets
� Classic cancer therapies target rapidlydividing cells ± Radiation
± Chemotherapy
� Side effects ± Hair loss
± Weakened immune system
± Digestive tract issues
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 27/28
Cancer therapies target
� immune system may not target tumor cells because they appear to be ³self´
� Some therapies activate one's immunesystem against a cancer
8/6/2019 The Cell Cycle and Cancer 2011
http://slidepdf.com/reader/full/the-cell-cycle-and-cancer-2011 28/28
Cancer therapies target
� Modern, therapies attack specificproteins that are abnormally expressed
in a tumor
± Block over-expressed growth factor
receptors --> Herceptin
± Target cancer cells so less side effects.