In vivo models of investigating cancer Flashcards
1
Q
Describe control of cell delamination in development
A
- example = c.elegans
- basement membrane separates vulva and uterus cells
- connection needs to be broken by breaking basement membrane
- done by anchor cell
- creating an extension of very dynamic protrusions that make a hole in the BM
- squeezing through the hole-coming in contact with vulval cells
- formation of the mature uterine-vulval connection
2
Q
What are some molecular modulators of tumour progression?
A
Fos - a proto-oncogene associated to cancer cell invasion
Rho-GTPases and Rac - regulators of F-actin dynamics
- MMPs - remodel the ECM
3
Q
What is the effect of mechanical pushing?
A
- may help in breaching through the BM - therefore MMP inhibitors are not that successful in treating tumours
4
Q
What are the requirements of the anchor cells?
A
- needs to be arrested in G1 while invading the vulval epithelium - invasion as a cooperative process - with some cells aiding in migration and not proliferating - while others continue proliferating and are dragged along
5
Q
Describe cell migration by border cells in d.melanogaster (fruit flies)
A
- polar cells activate motility in neighbouring cells - they secrete a cytokine (unpaired)
- migratory border cells carry polar cells = they respond to unpaired by activating a kinase (JAK) and a transcription factor (Stat) downstream
- the JAK-Stat pathway is involved in cancer cell motility
- learning about mechanisms of border cells collective migration teaches us about cell migration in cancer
6
Q
Describe oogenesis in drosophila
A
- each ovary is formed by several ovarioles - an egg chain production
- the oocyte matures within the egg chamber
- nurse cells generate all the nutrients and maternal RNAds that the oocyte needs to be mature
- the oocyte acquires a polarity - border cells are important to confer the polarity
7
Q
What is the traditional method to study tumour progression?
A
- mice = primary model
- mouse mutant strains prone to develop a particular cancer
- use immunocompromised mouse strains to perform xenotransplants
8
Q
Why is the zebrafish a good model system to study tumour progression?
A
- cheaper
- allows imaging in vivo
- high throughput screen for therapeutic approaches
9
Q
Describe transgenic melanoma models in zebrafish
A
- 50% of advanced melanomas contain a mutation in the BRAF gene
- BRAFv600E is the most common mutation
- BRAF is a kinase and the V600E mutation leads to formation of a constitutive active form
- a transgenic zebrafish was generated that express BRAFv600E in the melanocytes
- these transgenic fish develop malignant melanomas
10
Q
How are transgenic fish visualised?
A
- GFP labelling
- does not label differentiated melanocytes
- BUT metastatic melanoma cells present features of neural crest progenitors and re-express GFP
- can be visualised
11
Q
How can zebrafish be used for cancer drug discovery?
A
- zebrafish models that develop tumours in embryonic/larval stages are useful for high-throughput drug discovery screens
- Tg(mitfa:V12Ras) = transgenic line expressing oncogene Ras in the melanocytes from the moment of their specification
- these fish develop too many melanocytes from the embryonic stages - larvae are hyper-pigmented
- as they grow, the adults eventually develop melanoma
- screening for chemicals that revert hyperpigmentation in Tg(mitfa:V12HRas)
- these chemicals are potential suppressors of melanoma progression
12
Q
Describe how drugs can be discovered using melanoma cells
A
- metastatic melanoma cells present features of neural crest progenitors
- if we find drugs that suppress neural crest formation, they may also work suppressing melanoma progression
- combination of drugs worked preventing progression = in melanoma cell culture, in mouse xenografts
- leflunomide has been taken forward into phase I/II clinical trials
