Lecture 11.2: Neoplasia 2 Flashcards
True or false? Most cancers are sporadic.
True. There is no known inheritable trait involved.
What are the 4 classes of normal regulatory genes that are principle targets of neoplasia?
Growth promoting oncogenes. Growth inhibiting tumour suppressor genes. Apoptotic genes. DNA repair genes.
Where are the areas in a gene that SNPs can occur. What happens in each case?
Outside the gene, has no effect on protein production/function. Non-coding part of gene that may change amount of protein produced. Coding part that completely changes amino acid sequence.
What do point mutations do in the gene?
Change function or expression.
What do copy number changes do?
Expression levels. Example is N-MYC gene.
What are the major proliferation pathways in cancer?
Tyrosine kinase pathway. Activates RAS pthway, changes gene in nucleus via two methods: PI3 and/or MAPK.
PI3 has a PTEN tumour suppressor. It can itself also be mutated where it is inactivated or completely deleted.
Sometimes MAPK itself can be mutated to be activated spontaneously.
True or false? Suppressor effects can be induced by DNA methylation whereby there is hypermethylation.
True.
Explain how miRNAs can help control tumours. And what happens when that all goes wrong.
They are transcribed not not translated pieces of micro RNA that serve to regulate transcription and translation of genes. We may not have enough, leading to over expression of oncogenes. Or we may have too much, which can target tumour suppressor proteins.
Explain the significance of p53.
Transcription factor that regulates expression of cell cycle factors. Itself can be mutated or deleted leading to inability to induce apoptosis, cell cycle arrest, DNA repair, differentiation, senescence.
Which oncogenes are known as tumour suppressors?
MYC and RAS.
What are the two pathways in which tumours can occur?
Decreased apoptosis, which has two pathways.
Extrinsic which is ligand mediated, CD95 is the main receptor.
Intrinsic, caused by stress, chemicals, radiation, where decreased BAX (pro apoptotic from loss of p53) and increased BCL2 (pro apoptotic) occurs.
What are the three cellular glues that are dysfunctional in metastasis?
Catenins, connexins, integrins.
