Cancer as an Infectious Disease - Test 1 Flashcards
What was the conclusion from cancer research in the 1970s?
- Virus-induced cancers represent only a minority of the cancer types affecting humans
What was cancer considered as?
- A candidate for infectious disease
In 1911 what virus caused cancer in chickens?
- Rous Sarcoma Virus (RSV)
- A virus can transform a normal cell into a tumor
- Rous’s protocol for inducing sarcomas in chickens
What were the two categories of disease in the 19th century?
- Bacteria - trapped in pores upon filtration
- Viruses - pass through filters
Density Dependant Inhibition (contact inhibition)
The behavior exhibited by cells propagated in monolayer culture reflects the halt in cell proliferation.
Anchorage dependence
Requirement of cells for tethering to a solid substrate before they will grow.
Cancer cells do not exhibit…
- Anchorage Dependence
- Density Dependence
Transformation
- Process of converting a normal mammalian cell into a cell having some or many attributes of a cancer cell
Transfection
- a procedure for introducing DNA or RNA molecules into cells which may thereafter be expresses transiently in such cells, in case of DNA, stably in such cells
Transduction
- [as in signal transduction]
- Process by which a gene is introduced into a cell, usually by a vector such as a viral vector.
Immortalization
- Process whereby a cell population normally having limited reproductive potential acquires the ability to multiply indefinitely
Tumorigenicity
The ability of cells to serve as founders of new tumors is often gauged experimentally by transplanting cells into appropriate hosts.
Tumorigenic
- Referring to the ability of cells to form tumors when introduced into appropriate animal hosts
Tumorigenesis
The process of forming a tumor,often involving a succession of steps.
What becomes integrated into the chromosomes of infected cells?
Retroviral genomes
Provirus
- a virus genome that is integrated into the DNA of a host cell.
How does RSV transform cells?
- It exploits a kidnapped cellular gene
SRC gene
- specifies the src protein which causes cell transformation
- src was named to indicate its role in triggering the formation of sarcomas in infecting chickens
Where were src sequences present?
- In the genome of uninfected cells
What does src possess the properties of?
It possesses the properties of a normal cellular gene
- The relation “created a revolution in thinking about the origins of cancer”
What are tree ways that retroviruses contribute to tumorigenesis?
- Carry an oncogene acquired from a cellular proto-oncogene precursor
- Upregulate cellular porto-oncogenes through “insertional mutagenesis” thereby converting the port-onogene into an oncogene
- Naturally carry oncogenes
What classes of DNA viruses are able to induce cancer?
- papilloma virus
- polyomavirus
- human adenovirus
- herpesvirus
- poxvirus
DNA tumor virus genomes
- integrate into host-cell chromosomal DNA which allows for transmission of viral DNA sequences
T antigen
Tumor-associated protein
SV40 large T antigen
- Product of an early gene
- Involved in viral genome replication and virion assembly
- Capable of inducing malignant transformation of a variety of cell types largely through disrupting pRb and p53
Gastric carcinoma
- Bacterial Cancer -Most deaths resulting from stomach cancer are due to chronic infection by pathogenic strains of the common bacterium
How does H. Pylori cause stomach cancer?
- Chronic, long-term infections and associated inflammation
- Cag pathogenicity island (PAI), carried by certain H. pylori strains, encodes the CagA protein.
The bacteria inject CagA into gastric epithelial cells where it deregulates cellular signals resulting in transformation-related phenotypes
