What Is Cancer?
Dr Anil Mohith
Medical Oncologist
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What Causes Cancer?
Some viruses or bacteria
Some chemicals
Radiation
Heredity
Diet
Hormones
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Different Kinds of Cancer
Some common
carcinomas:
Lung
Leukemias:
Bloodstream
Lymphomas:
Lymph nodes
Breast (women)
Colon
Bladder
Prostate (men)
Some common
sarcomas:
Fat
Bone
Muscle
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Loss of Normal Growth Control
Normal
cell division
Cell Suicide or Apoptosis
Cell damage—
no repair
Cancer
cell division
First
mutation
Second
mutation
Third
Fourth or
mutation later mutation
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Uncontrolled growth
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Example of Normal Growth
Dead cells
shed from
outer surface
Epidermis
p
Dividing cells
in basal layer
Cell migration
Dermis
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The Beginning of Cancerous Growth
Underlying tissue
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Invasion and Metastasis
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Cancer cells invade
surrounding tissues
and blood vessels
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Cancer cells are
transported by the
circulatory system
to distant sites
3
Cancer cells
reinvade and grow
at new location
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Microscopic Appearance of Cancer Cells
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Normal Cell Communication
Genes
mRNA
Cell
divides
Proteins
Cell
autodestructs
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Some communications pathways
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Cancer: A Communication Failure
Colon
Retinoblastoma,
bone, bladder,
lung,
g breast
Many
y cancers
Genes
mRNA
Proteins
Sarcomas
Leukemia,
brain,,
breast,
stomach,
lung
Leukemia
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Some neuronal tumors
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Genes and Cancer
Viruses
Chemicals
Radiation
Heredity
Chromosomes
are DNA
molecules
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Expression Changes With Cell Type
Myosin mRNA
Myocyte has both
genes, but . . .
Myosin gene
Myocyte makes
myosin mRNA and
not immunoglobulin mRNA
Lymphocyte has
both genes, but . . .
Immunoglobulin gene
No immunoglobulin mRNA
No myosin mRNA
Myosin gene
Immunoglobulin gene
Lymphocyte makes
immunoglobulin mRNA
and not myosin mRNA
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Immunoglobulin mRNA
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Human Genome Project
Chromosome X
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Examples of
Dominantly Inherited Cancer Syndromes
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DNA Mutation
DNA
CA AG C T A A C T
Normal gene
CA AG C G A A C T
Single base change
CA A G G CG C T A A C T
Additions
C
T
CA A G A A C T
Deletions
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Oncogenes
Normal cell
Cancer cell
Mutated/damaged oncogene
Normal
genes
regulate
cell growth
Oncogenes
accelerate
cell growth
and
d division
di i i
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Tumor Suppressor Genes
Normal
genes
prevent
cancer
Normal cell
Remove or inactivate
tumor suppressor genes
Cancer cell
Damage to
both genes
leads to
cancer
Mutated/inactivated
tumor suppressor genes
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p53 Tumor Suppressor Protein
Triggers Cell Suicide
p53 protein
Normal cell
Excessive DNA damage
Cell suicide
(Apoptosis)
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DNA Repair Genes
Normal DNA repair
T C GA C
Base pair
mismatch
No cancer
TC T AC
AG C T G
TC TAC
TCT AC
AG C T G
Cancer
AG
TG
AG A T G
No DNA repair
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Cancer Tends to Involve Multiple Mutations
Benign tumor cells
grow only locally and
cannot spread by
i
invasion
i
or metastasis
t t i
Malignant cells invade
neighboring tissues, enter
blood vessels, and
metastasize
t t i to
t different
diff
t sites
it
Time
Mutation
Cells
inactivates proliferate
suppressor
gene
Mutations
inactivate
DNA repair
genes
Proto-oncogenes
mutate to
oncogenes
More mutations,
more genetic
instability,
metastatic
disease
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Example: Translocation of Bcr-Abl Genes
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9
(q+)
Ph
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bcr
(22q–)
bcr-abl
abl
Fusion protein
with tyrosine
kinase activity
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Molecular Diagnostics
Old Way
Patient’s
tissue sample
Pathology
Proteomics
Proteins
New Way
Mass spectrometry
Proteomic image
Genomics
Patient’s
tissue sample
or blood sample
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DNA
Gene chip
Microarray image
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THANK YOU
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