L22 - Behaviour of tumours Flashcards
what is neoplasia?
● An autonomous proliferation of cells
● Loss of normal growth control
● Tumour: literally any swelling
what does benign mean?
No local invasion; no metastasis
what does malignant mean?
Local invasion and metastasis
what is hypertrophy?
enlargement in individual cell size
what is hyperplasia?
increase in number of cells
what is metaplasia?
replacement of mature tissue types/change from one type to another
what is dysplasia?
abnormality indicating precursor change of malignancy
cell types not where they’re supposed to be
what is anaplasia?
failure to differentiate
how do malignant tumours behave?
- invasion
- metastasis
- angiogenesis
what is invasion?
- invades adjacent structures
- destroys normal tissue
what is metastasis?
spread to distant sites/forms new tumours in new areas
what can cause a tumour to undergo invasion?
➢ Increased motility [from solid tissue to a mesenchymal]
➢ Decreased adhesion [lose tissue component]
➢ Production of proteolytic enzymes [to lose the fixed components keeping them in place]
➢ Mechanical pressure [can also cause local invasion]
what are the adhesion molecules that attach cell to cell?
cadherins
what are the adhesion molecules that attach cell to extracellular matrix?
integrins
what would happen if a mutation of e-cadherins was to occur?
loss of cell-cell adhesion and contact inhibition
what would happen if changes in integrin expression was to occur?
lead to decreased cell-matrix adhesion (cell would be mobile)
In cancer epithelial cells gain mesenchymal properties, what does this mean?
they can become loosely connected, able to migrate
which enzyme degrades collagen type I, II, III?
interstitial collagenases
which enzyme degrades collagen type IV and gelatin?
gelatinases
which enzyme degrades collagen type IV and proteoglycans?
stomolysins
collagen type I is the main component of what?
skin
collagen type II is the main component of what?
hyaline and cartilage
collagen type III is the main component of what?
bone
collagen type IV is the main component of what?
basement membrane
what are Proteolytic Enzymes?
Matrix Metalloproteinases
degrade extracellular matrix (allows local invasion)
how can benign tumours cause damage?
mechanical pressure
- Pressure occludes vessels
- Pressure atrophy
[Even though not malignant, surrounding tissues can be destroyed due to
compression of feeding vessels causing atrophy]
in metastasis which is often the most damaging tumour - the primary or secondary site?
Secondary tumour burden is often greater than that of the primary site
list routes of metastasis
- lymphatic
- blood
- transcoelomic
- implantation