Transcript Carcinogenesis – The Development of Cancer

Cancer
A power point presentation by Mr. C
2005
Carcinogenesis – The
Development of Cancer
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Mitosis gone mad…
Extra Spindle
Apparatus
Extra Centriole
METAPHASE
PROPHASE
INTERPHASE
Extra Centriole
EARLY TELOPHASE
ANAPHASE
Abnormal Nuclear
Cluster
LATE TELOPHASE
Unequal Daughter
Cells, with abnormal
Nuclei formed
Oncogene initiation
Promoter Sequence for
Regulator Gene
Transcription
Translation
Regulator Gene
Binding Site
for Repressor
Structural Genes
Generation
of oncogene
by radiation
RNA
Human Cell
protein coat
RETROVIRUS
Virus releases its nucleic acid into Cell
DNA
The viral enzyme "reverse Transcriptase" turns viral RNA into
double stranded DNA.
cDNA incorporates itself into host's own DNA
- this could "switch on" an oncogene.
Normal Tissue with a few abnormal
cells growing and dividing (anaplasia).
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THE FOUR BASIC CHARACTERISTICS OF CANCER
CELLS
The cells of the cancer, at least at its beginning, must
have been derived from a single cell that went wrong.
The cell must have independent ability to divide
continuously and out of control.
The cell must be able to separate from its neighbouring
cells and move to a new location where a new mass of
cells will develop.
When a cancer cell divides, it often results in a cell with
an abnormal number of chromosomes, either more or
less than the normal complement. This characteristic
varies strongly with the type of cancer. In some cancers,
the cell divisions are perfectly normal.
THE SEVEN DANGER SIGNS OF
CANCER
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1. A change in bowel or bladder habits.
2. A sore that doesn't heal.
3. Unusual bleeding or discharge.
4. A thickening lump in the breast or
elsewhere in the body.
5. Indigestion or difficulty in swallowing.
6. Obvious changes in a wart or mole.
7. A persistent nagging cough or
hoarseness.
Ways to memorize signs
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Cough
Change
Lump
Indigestion
Mole
Bleeding
Sore
C
Climbs
Review of Carcinogenesis –
The Development of a Cancer
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1) INITIATION
a chemical (e.g. cigarette smoke,
asbestos, benzene, DDT) or radiation (e.g.
U.V. light, X-rays, gamma rays) mutagen
causes a mutation in DNA that turns a
protooncogene into an oncogene.
The mutagen that does this is called an
INITIATOR.
2) PROMOTION
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Exposure to a promoter after initiation
will speed up the development of
cancer.
e.g. a promoter could be cigarette smoke,
U.V. light, a high fat/low fiber diet.
Promoters trigger uncontrolled
growth.
3) TUMOR DEVELOPMENT
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uncontrolled growth of cancerous cells. (a
new growth of cancerous cells is called a
neoplasia).
a primary tumor forms.
the cells of the tumor are undifferentiated and
resemble embryonic cells (this property of
cancer cells is called anaplasia).
the tumor cells release chemicals that cause
increased vascularization of the tumor (i.e.
more blood vessels grow towards the tumor).
The tumor cells release proteases that allow the
tumor to grow into surrounding tissue.
METASTASIS
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Tumor cells acquire the ability to break free
from the primary tumor and invade blood
vessels or lymph vessels.
These cells travel in the blood or lymph, and
go to other sites in the body, where they leave
the blood or lymph and grow into new
tumors (called secondary tumors)
Cancer at this stage is very difficult to treat
effectively.