Cancer Genetics Flashcards
How do cancer cells arise?
Cell growth is highly regulated
When cells are derailed how are new cells produced?
uncontrolled proliferation
What is the difference between cell masses of tumours or neoplasms?
Tumours - cancerous
Neoplasms - new growth
What does transformation mean?
Process of changes within a cell that lead to a neoplasm
What are 2 types of neoplasm?
Benign - localised
Metastatic - spread
What are familial cancers?
Inherited in families - high penetrance in genes
What are sporadic cancers?
Acquired in ones life time - combo of low pentrance genes
What are cancer cells in situ?
Clonal
What part of chromosomes are associated with cancer?
Aberrations
What are mutagens?
Exposure to chemicals that damage DNA
What type of infection can lead to cancer?
oncovirus
What is carciogenesis?
Process of inducing cancer
Which 2 genes do mutations arise in?
Oncogenes and Tumour surpressor gene
What are 4 types of mutations?
Single letter change, reverse order, deletion, insertion
What type of genetic changes in oncogenes?
1 change, gain of unction, stimulate cell growth, myc, ras
What type of genetic changes in tumour suppressors?
2 genetic changes, loss of function, repress cell entry - pRb, P53
What are proto oncogenes?
Genes which encode for components of cell signalling pathways
What do proto oncogenes promote?
Cell growth and division
What happens to proto oncogenes when mutated?
Become oncogenes - drive cell to divide
What do oncogenes trigger?
Cell transformation
What are viral oncogenes?
Copies of a group of genes found in humans
What do proto-oncogenes control?
Key process in cell growth such as factors, receptors, signalling, transcription
When does proto-oncogenes become activated oncogenes?
Gain of function by amplification, mutation and chromosomal rearrangement
Why is HER 2 an example of oncogene?
30% have this, increased her2 receptors on cell surface - amplification
Why is Ras an example of oncogene?
Signal transducer protein - active and inactive form 1/3 have it
Why is VEGF an example of oncogene?
Vascular endothelial growth factor - over produce this and sprouts new vessels feeding cancer - target avastin
What is theact of cancers creating new blood vessels?
Angiogenesis
What inhibits angiogensis?
Anti angiogenesis - avastin
Where do tumour suppressor genes work?
At cell cycle check points
What are 3 classfications of TSG?
Gatekeeper
Caretaker
Landscaper
What do Gatekeeper genes do?
regulate cell division
What do Caretaker genes do?
DNA repair
What do Landscaper genes do?
Modulate stroma for tumour to grow
Why are mutations in TSG recessive?
Both alleles must be mutated for gene to stop functioning
Why is Rb an example of TSG?
People can inherit one faulty copy and later in life lose second copy and be cancerous
Why is p53 an example of TSG?
Known as gaurdian of genome needed for apoptosis
Why is BCRA 1 and BRCA 2 an example of TSG?
Encode DNA repair enxymes and when mutated can accumulate
What does BRCA 1 regulate?
Microtubules for taxane resistance
How do Viruses assist cancer?
Enhance proliferation and predispose cells to cancer - CANT induce IT
What does protein does DNA make to inactivate tumour surpressors?
Viral proteins - mesotheliomas
What does RNA viruses insert for viral promotion?
Avian model
What do RNA viruses carry to activate oncogene?
Avian sarcoma
What does HPV E6 /E7 inactivate?
P53 and Rb
What also inactivates P53 and Rb?
SV40 TAg and AdE1a,b - Rb and P53
What does two hit hypothesis define?
Min number of mutations for tumour to occur
For cancer to develop what 6 stuff must cells acquire?
External growth signals Anti-growth signals Apoptosis Immortality Angiogenesis Metastatic
What does FAP lead to?
Colon cancer
What can transformation process lead to?
Neoplasms
What are 2 types of neoplasms?
Benign or Malignant
What facts indicate cancer is genetic?
Familial cancers, Oncoviruses, Mutagens
What do the Mutations that cause cancer disrupt?
Cell cycle checkpoints
What aberration causes a gain of function event?
Proto-oncogenes to oncogenes
What genes prevent uncontrolled cell division?
Tumour Suppressor genes
How do TSG stop cell division?
Deactivated in cancer by recessive mutations in both alleles
