Lecture 16 Flashcards
is cancer more prevalent in men or women?
men
where does tissue repair often come from?
often comes from basal stem cells - if they are lost they can be made again from differentiation
what are the 5 types of abnormal cell growth?
Hypertrophy - increase in cell size
Hyperplasia = increase in cell number
Metaplasia = change in cell differentiation - replacement of one mature cell type with another mature cell type
Dysplasia = change in cell differentiation - replacement of one mature cell type with another less mature cell type
Neoplasia = cancer - irreversible tissue changes caused by mutations
what is the difference between neoplasia and the other type of abnormal cell growth?
- the other types are reversible because they are results of a stimulus
- neoplasia is irreversible because it is autonomous
what is cancer (4 things)?
1) uncontrolled cell proliferation ie mitosis
2) abberant differentiation doesnt follow normal balance between proliferation and differentiation
3) uncontrolled cell interaction- invasion and metastasis (tumors invade adjacent tissues)
4) Cancer cell host interactions - need blood supply (angiogenesis), produce hormones, interaction with immune system
what is metastasis, what are common sites of it and why?
- the development of secondary malignant growths at a distance from a primary site
- pass in blood cells to distant sites and colonise them
- cancer and lungs are common sites due to all our blood passing through these organs
what is the difference between benign and malignant tumors?
benign = confined well defined structures malignant = dysplasia, anaplasia(severe dysplasia), invasion, metastasis
4 things which cause cancer?
1) chemical - smoking
2) Parasites - proteins they make can cause cancerous changes to cell division
3) Viruses - insertion into genome
4) Radiation - uv
describe the general stochastic model for cancer
- mutations making a cell into a tumour initiating cell
- Tumour is made of a mix of cell types
- Small genetic changes - all grow slightly differently
- All cells in the tumour are tumour initiating - individually - each cell would give rise to a tumour
- Chance what the tumour composition is
- Cells die off and environment will effect it
- most cells are capable of contributing to tumour growth and evolving to be resistant to treatment
what are problems with the stochastic model?
1) get recurrence of tumours even when thought everything is killed off
2) Tumour properties are very heterogenous - diverse in content - contain lots of differentiated cells
- sounds like a stem cell system - tumour initiating cells aren’t killed off and just reactivate
heterogeneity extends to virtually all measurable properties of cancer cells, what are these properties?
1) differentiation state
2) proliferation state
3) migratory and invasive capacity
4) size
5) therapeutic response
what are the implications of tumour heterogeneity?
- not every tumour is the same
- only some some cells can give rise to cells with higher proliferative capacity
- only some cells appear to be tumour initiating cells
describe the ‘cancer stem cell’ model
- only a small definable subset of cancer cells are tumour initiating cells that have the ability to proliferate indefinitely
- ability to self renew and give rise to the phenotypically diverse tumour cell population to drive tumerogenesis
- Regulated by the same pathways - assymetric division - which Is the disregulated in cancer cells
- Not necessarily a stem cell to start with that got mutated - could be a cell that got mutated leading to it becoming/ acquiring the properties of a stem cell which gives rise to a tumour
describe the difference between normal stem cells and cancer stem cells?
normal = rare cells within organs with the ability to self renew and give rise to all types of cells within the organ to drive organogenesis cancer = rare cells within tumours with the ability to self renew and give rise to the phenotypically diverse tumour cell population to drive tumorigenesis
what are properties shared by normal stem cells and cancer stem cells?
1) assymetric division - both self renew to maintain organs and tumours
2) regulated by similar pathways
3) differentiate and give rise to heterogenous population of cells that compose the organ or the tumour but lack the ability for unlimited proliferation (hierarchy)
