11. Cancer cell death Flashcards
Define apoptosis
Programmed cell death occurring as a normal part of organisms growth and development - this is active
Define necrosis
The death of tissue due to injury, disease or ischemia - this is passive
What happens to the nucleus during apoptosis?
The nucleus and genetic material condenses
What happens to the mitochondria during apoptosis?
The mitochondria condense
What are the morphological features of apoptotic cells?
Cellular and nuclear condensation
Nuclear fragmentation
Nuclear and mitochondrial condensation
Cellular fragmentation
What can apoptosis be induced by?
Heat shock Viral infection Toxins Oncagenes Free radicals Nutrient deprivation Chemotherapeutic drugs Radiation
What is meant by ‘immunogenic cell death (ICD)’?
A cell death modality that does stimulate an immune response against dead-cell antigens - in particular when they derive from cancer cells
When is ATP released during apoptosis?
During the blebbing stage
What is the main organelle responsible for the regulation of apoptosis?
Mitochondrion
What are lymphocytes?
WBC in the blood and the lymphoid organs
B cells
T cells
NK cells
What are phagocytes?
WBCs that can swallow and digest microscopic organisms via phagocytosis
What are monocytes?
What do monocytes differentiate into?
Circulate in the blood and differentiate into macrophages and dendritic cells
What are dendritic cells?
Specialised antigen presenting cells to the immune system
Where are immune cells produced?
Precursors in the bone marrow
Where are immune cells derived from?
Haematopoetic stem cells
What are the functions of T-cells?
Killing (cytotoxic) , activation (helper) and regulation (regulatory t cells)
How can cancer cells escape immunosurveillance?
Altering their characteristics e.g. downregulation of MHC I
Suppressing the immune response e.g. immunosuppressive cytokine
Outpacing the immune response - proliferate faster than the immune system can kill them
What cells do NK cells work on?
NK cells kill cells coated with an antibody
What are PAMPs recognised by?
These are recognised by toll-like receptors in the innate system on dendritic cells and macrophages
What are PAMPs recognised by?
These are recognised by toll-like receptors in the innate system on dendritic cells and macrophages
What are the cells of the innate system?
Granulocytes: neutrophil, eosinophil, basophil, monocyte
What are the cells of the adaptive immune system?
Lymphocytes - B cells (humoral) and T-cells (cellular)
What are the cells that bridge the gap between the innate and the adaptive immune system?
Dendritic cells
How does the immune system kill cancer cells?
T cells - CD8 and CD4+ B cells - antibodies Cytokine release Dendritic cells NK cells - activated for direct killing of the tumour cells Macrophages - antigen presenting
What cytokines are involved in cancer cell death?
IFN-alpha
IL-2
IL-12
GM-CSF
How many times can a normal human cell population divide?
Why?
52
The telomeres of the cell will get shorter and shorter each time the cell divides until they shorten to a critical length
