metastasis 1 Flashcards
what is metastasis
the process where cancer cells that originate in one part of the body end up in other places and form secondary tumours
where do prostate cancer cells normally metastasise to
bone marrow
where do colon cancer cells normally metastasise to
liver
where do breast cancer cells normally metastasise to
lungs and bone marrow
where do pancreatic cancer cells normally metastasise to
liver
overview of metastasis - 6 steps
primary tumour forms, the tumour cells invade into surrounding tissue, they meet barriers e.g. blood vessel walls and so they start to break through (intravasation), they interact with blood platelets and immune cells when in blood, they attach to the blood vessel wall and do extravasation. they then multiply and form a micrometastasis from there colonization occurs where a 2º tumour forms
why do cancer cells have to invade surrounding tissues
they divide more than they need to and they arent dying so there is a big mass of cells
what is intravasation
to invade across a blood vessel barrier and get into the blood supply
what is extravasation
moving out the blood vessel
what is a micrometastasis
a very small collection of tumour cells that are in a different location
what happens to most micrometastasis’
they invade new tissue and form and don’t grow
what is another name for 2º tumours
macrometastasis
define epithelial cell
cells that line tube structures
properties of epithelial cells (4)
polygonal/columnar shape, apico-basolateral polarisation, strong cell-cell adhesion, limited migratory potential
what is apico-basolateral polarisation
a type of cell polarity specific to epithelial cells, they have different faces
what cell is an example of a mesenchymal cell
white blood cell
difference between epithelial and mesenchymal cells in relation to movement
mesenchymal cells move around whereas epithelial cells stay in the same place
what are the markers for epithelial cells (4)
E-cadherin, certain cytokertins, occludin, claudin
what is e-cadherin
cell surface protein that acts as a molecular ‘velcro’ that sticks cells together
properties of mesenchymal cells (4)
spindle shape, anterior-posterior polarization, focal cell-cell contacts, strong migratory potential
markers for mesenchymal cells (3)
vimentin, N-Cadherin, fibronectin
what does apical mean
top surface
what does basolateral mean
side surfaces
what does “spindle-shaped” mean
pointy
what does anterior-posterior polarisation
they have a head and a tail, they have a directionality
what are focal cell-cell contacts
grabbing onto something and pulling themselves along, make and break contact
epithelial gene expression programme
epithelial cells have the ability to make all the proteins they need to be epithelial cells
what type of protein is E-cadherin
transmembrane protein
what does it mean when you say E-cadherin can dimerise
a molecule of E-cadherin can interact with a molecule of E-cadherin from another epithelial cell
what happens to epithelial cells in cancer
they can change into mesenchymal cells and start interacting with the extra cellular matrix
what do epithelial cells lose when they become cancerous (4)
cytokeratin expression, tight junctions and junctions involving e-cadherin, epithelial cell polarity, epithelial gene expression program
what do epithelial cells acquire when they become cancerous (6)
fibroblast-like shape, motility, invasiveness, increased resistance to apoptosis, mesenchymal gene expression program, mesenchymal adherens junction protein (N-cadherin)
what makes a cell be able to change its gene expression program
transcription factors
what do most EMT (epithelial-mesenchymal transition) transcription factors do
repress E-cadherin expression
what does TWIST transcription factor do
binds to DNA and represses the promotor of the CDH1 gene which produces e-cadherin. Cell becomes mesenchymal
TWIST cancer association
lots of cancer cells have high levels of TWIST, it induces cells to migrate to different places and its meant to be just in the embryo but cancer cells produce it anywau
3 other examples of genes/proteins that repress E-cadherin
Goosecoid, Slug (SNAI2), Snail (SNAI1)
what is the basement membrane made of
proteins - collagen fibre network
how do cancer cells get through the basement membrane
they produce matrix metalloproteinases (MMP-1)
what is MMP-1
a gene that encodes collagenase-1
what does collagenase do
breaks down collagen, can break up collagen fibres in basement membrane
what does the degradation of the extra cellular matrix produce
growth factors, which can then help cells to grow
