a) w/c 6-Jan-14 Tumours/Repro Flashcards
(115 cards)
p53 is an example of what type of gene?
Both p53 and Rb protein are examples of TUMOUR SUPRESSOR GENES (BRAKE ANAOLOGY).
For suppresion to be stopped, need both copies to be mutated/deleted
White haired cats are suspectible to which type of UV radiation induced cancer?
Squamous cell carcinoma (ear tips, nose)
The opposite of tumour supppressor genes are known as_____
mitogens Stimulate cell proliferation.
Aka proto-oncogenes e.g. Ras/Raf
5 hallmarks of cancer
- Resisting cell death
- Sustaining proliferative signalling
- Inducing angiogenesis
- Enabliing replicative immortaility
- Evading growth suppressors
- Activating invasion and metastasis
Two types of cancer boxers are predisposed to
Lymphoma and mast cell tumours = boxers are a walking neoplasm.
German shepherd dogs: haemangiosarcoma
3 ways cancer cells can undergon uncontrolled proliferation
- Secretion of endogenous growth receptors
- Mutation of growth factor receptors. Constitutively activate in absence of growth factor. e.g. canine mast cell tumour KIT mutation
- Mutation of intraceullar signalling molecules. Activating proto-oncogenes e.g. Ras/Raf
Rb protein transduces growth-inhibitory signals that originate largely _____
Rb protein OUTSIDE the cell. Determines whether or not the cell cycle progresses
p53, another tumour suppresor gene recieves input from ___ mechanisms
Intracellular mechanisms, if cell viability is suboptimal it calls a halt to cell cycle progression
Can Rb and p53 trigger apoptosis via the caspace cascade? If so, which pathway is involved?
ONLY P53 can trigger APOPTOSIS via the INTRINSIC PATHWAY leading to CASPASE cascade (i.e. intracellular)
What is the significance of the Bcl-2 family in oncogenesis?
Cancer cells need to resist cell death. Regulated cell death has two mechanisms. Intrinsic and Extrinsic pathway.
Cancer cells can downregulate death receptors or UPREGULATE Bcl-2 family which blocks the INTRINSIC pathway
How can tumour cells avoid the EXTRINSIC pathway of cell death?
Cancers can downregulate the death receptors on the cell surface (i.e. extrinsic pathway)
c.f. with intrinsic pathway –> p53 intracellularly. Cancer cells can UPREGULATE Bcl-2 family
Which specialised DNA polymerase is upregulated in cancer cells to enable replicative immortality?
Normal cells undergo cellular senescence due to shorted telomeres (protect end of chromosomes)
Cancer cells contained DNA polymerase Telomerase which adds telomere repeat segments = immortality
Why do tumour cells need to induce angiogenesis? How do they do this?
Once a tumour reaches a critical size, is at risk of hypoxia-induced cellular necrosis therefore requires a blood supply.
SECRETE ANGIOGENIC FACTORS such as Vascular Endothelial Growth Factor (VEGF).
Faciliates metastasis/ Haematogenious spread
What do CARCINOMA cells use to metastasise?
Loss of E-cadherin by carcinoma cells allows them to detach from primary tumour and spread.
- Local drainage LN
- Liver
- Lungs
- Bone Marrow
Significance of tumour-promoting inflammation?
Some tumours demonstrate a significant infiltration of inflammatory cells. Although its an attempt to eradicate it can be COUNTERPRODUCTIVE.
Inflammatatory cells can supply bioactive molecules e.g. growth factors, immunosuppressive mediators
DDx for cancer tumour?
Abscess (systemically ill? pyrexia?), grauloma, haematoma, seroma, cyst
How could a haematoma be differentiated from a tumour?
Painful? Hot? Fluid-filled? Well-defined or ill-define? Fixed to under lying tissue?
What steps should be undertaken when a tumour is identifed?
Cytotoly (fine needle aspirate), no negative pressure to start with, evaculate syreinge using air.
Why is Histopathology preferred to cytology?
Histopathology: Tissue- Gives information on cell type and morphology/ tissue architecqture
Cytology: Cells
Both cytology and histopathology can both examines cell morphology for signs of malignancy (mitotic index, megakaroyocyte)
A fast growing tumour is more likely to be ____
malignant than a slow growing tumour.
Benign tumours grow by expansion
Malignant tumours grow more rapidly and disrupt surrounding tissues
Difference between tumour GRADE and STAGE?
Grade: Assigned by the PATHOLOGIST. low, intermediate or high grade
Stage: Assigned by the clinician. EXTENT of the disease in the patient. Use the TNM system
What is the TNM system?
T: Primary tumour: Size, mobility, relationship to surrounding tissue
N: Node: Assess the drainage LN (can be internal)
M: Distant metastasis. Imaging inc CT.
Most common site for metastasis in small animals?
Lungs. Can present with dyspnoea/ cough
X-ray, inflated radiograph, ideally 3
A tumour 3-5cm in diameter would have which TNM grade/
T2