Viruses to Cancer What is cancer?. Loss of Normal Growth Control Cancer cell division Fourth or...
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Transcript of Viruses to Cancer What is cancer?. Loss of Normal Growth Control Cancer cell division Fourth or...
Viruses to Cancer
What is cancer?
Loss of Normal Growth Control
Cancer cell division
Fourth orlater mutation
Third mutation
Second mutation
First mutation
Uncontrolled growth
Cell Suicide or Apoptosis
Cell damage—no repair
Normal cell division
Example of Normal Growth
Cell migration
Dermis
Dividing cells in basal layer
Dead cells shed from
outer surface
Epidermis
The Beginning of Cancerous Growth
Underlying tissue
Tumors (Neoplasms)
Underlying tissue
Invasion and Metastasis
3Cancer cells reinvade and grow at new location
1Cancer cells invade surrounding tissues and blood vessels
2Cancer cells are transported by the circulatory system to distant sites
Malignant versus Benign Tumors
Malignant (cancer) cells invade neighboring tissues, enter blood vessels, and metastasize to different sites
Time
Benign (not cancer) tumor cells grow only locally and cannot spread by invasion or metastasis
Microscopic Appearance of Cancer Cells
What Causes Cancer?Some viruses or bacteria
HeredityDiet
Hormones
RadiationSome chemicals
Viruses
Virus inserts and changes genes forcell growth
Cancer-linked virus
Examples of Human Cancer VirusesSome Viruses Associated with Human Cancers
Figure 3.3 The Biology of Cancer (© Garland Science 2007)
Replication & Variety of DNA Viruses
SV40 Virion
HPV 16 Virion
AIDS and Kaposi’s Sarcoma
Kaposi’ssarcoma
Withoutdisease
Depressedimmunesystem
HIV infection
KSHV infection
Genes and Cancer
Chromosomes are DNA molecules
Heredity
RadiationChemicals
Viruses
Proto-Oncogenes and Normal Cell Growth
Receptor
Normal Growth-Control Pathway
DNA
Cell proliferation
Cell nucleus
Transcriptionfactors
Signaling enzymes
Growth factor
Oncogenes areMutant Forms of Proto-Oncogenes
Cell proliferation driven by internal oncogene signaling
Transcription
Activated gene regulatory protein
Inactive intracellular signaling protein
Signaling protein from active oncogene
Inactive growth factor receptor
Tumor Suppressor Genes
Normal genes prevent cancer
Remove or inactivate tumor suppressor genes
Mutated/inactivated tumor suppressor genes
Damage to both genes leads to cancer
Cancer cell
Normal cell
Tumor Suppressor GenesAct Like a Brake Pedal
Tumor Suppressor Gene Proteins
DNACell nucleus
Signalingenzymes
Growth factor
Receptor
Transcriptionfactors
Cell proliferation
Figure 3.2 The Biology of Cancer (© Garland Science 2007)
RNA Tumor Viruses – The Rous Sarcoma Virus Story
Figure 3.22 The Biology of Cancer (© Garland Science 2007)
Virus OncogeneRous sarcoma virus v-srcSimian sarcoma virus v-sisAvian erythroblastosis v-erbA/BKirsten murine sarcoma v-kRasMoloney murine sarcoma v-mosMC29 avian myelocytoma v-myc
Viruses and Their Oncogenes
Figure 3.23b The Biology of Cancer (© Garland Science 2007)
Retroviral Insertion Has the Potential to Transform by Activation of Oncogenes
Many Types of HPVs
Different HPVs–Different Infections
Harmless
No warts or cancer
Warts-Linked
Genital warts
Cancer-Linked
Most clear up
Some persist, but no abnormalities in cervix
Some persist, some abnormalities in cervix
A few persist and progress to cervical cancer
Common Infection
Infected with HPV
Virus Penetrates Cervix
Uterus
HPVinfection
Vagina
Cervix
Layers of epithelial cells
Papillomavirus
Virus Uncoats
Virus “uncoats”
Nucleus
Epithelial cell interior
mRNAs for viral proteins E6 and E7
Viral DNA enters nucleus
Virus Disables Suppressors
Cancerous epithelial cells
Suppressor protein 2
E7 viral protein
Degraded suppressors
Healthy cellsMucus
E6 viral protein
Suppressor protein 1
The Vaccination
Antibodies Prevent Infection
Papillomavirus
No DNA strands can escape the capsid= Antibodies