Cell Senescence Flashcards
What is the single biggest risk factor developing cancer?
Age.
What is cell senescence?
A mechanism for preventing the proliferation of potential cancer cells.
Which stages of the cell cycle are most likely times senescent cells to stop proliferating?
G1 phase
G2 phase
What could cause a proliferating cell to become senescent?
Excess cell division
Short telomeres
Activated oncogene
Cell stress or damage
What is a nevus?
A mole
When are nevi acquired?
In utero or soon after birth.
How are nevi formed?
A melanocyte which acquires an activated BRAF or NRAS oncogene, the cells can proliferate and expand to form a cluster of pigmented melanocytes.
Why do nevi not progress to melanoma more frequently?
The cells are kept in a proliferation arrested state called cellular senescence.
Why do melanocytes sometimes progress to melanoma?
Partially due to inactivation of p16 or PTEN.
How was senescence originally discovered?
Hayfleck was growing cells in culture and found eventually cells just stop growing.
- the Hayfleck limit
Give examples of markers of senescence.
β- galactasidose, p16
What do senescent cells secrete?
Various cytokines and chemokines such as VEGF, IL6, IL8, Matrix metalloproteases.
Why is the senescence associated secretory phenotype thought to be important?
By bringing in immune cells it might promote clearance of damaged cells.
By secreting inflammatory molecules it could be detrimental to a tissue in the long term.
How do senescent cells promote tissue aging?
Blocking cell renewal.
Driving chronic inflammation.
They are inherently damaged cells that have a tendency to become diseased.
How do senescent cells inhibit cancer?
Damaged cells are prevented by progressing to cancer by senescence.
