Genetics - Cancer Flashcards
What is cancer?
it is a condition where cells in a specific part of the body grow and reproduce uncontrollably
These cells can invade and destroy surrounding healthy tissue, including organs
What are the five features of normal cells?
Uniform
There are few cells going through the cell cycle - majority in a stable state
Oncogene expression is rare
Tumour suppressor genes are present
These cells secrete growth factors intermittently and in a co-ordinated manner
What are the five features of cancerous cells?
Not uniform
There are lots of cells undergoing cell division - majority are in an unstable state
Oncogene expression is frequent
Tumour suppressor gene function is lost
These cells secrete growth factors at an increased rate
What are the three steps of cancer formation?
Initiation
Promotion
Progression
What two cancer formation steps are preclinical?
Initiation
Promotion
What cancer formation step is clinical?
Progression
What is the initiation stage of cancer?
This is when a mutation occurs within a single cell that results in its ability to no longer respond to normal cell signals
What are the three mechanisms of initiation?
Chemical
Physical
Viral
What is the promotion stage of cancer?
This when the mutated cell divides to form a number of other abnormal cells
What are the two mechanisms of promotion?
Growth factor secretion
Oncogene expression
What is the progression stage of cancer?
It is when the tumour invades local tissue and then metastasises to other parts within the body
What are the three enzymes involved in metastasis by destroying cell adhesions in the extracellular matrix so that the cancerous cells can move between them?
Matrix metalloproteinases
Plasmin
Cathepsin
What are the three enzymes involved in metastasis by allowing cancerous cells to adhere to the cells of another organ?
Cadherins
Integrins
CD44
What process occurs after metastasis?
Angiogenesis
What is angiogenesis?
This is the formation of new blood vessels
What are proto-oncogenes?
They are the normal genes that codes for proteins that regulate cell growth and differentiation
What are oncogenes?
They mutational proto-oncogenes that accelerate cell devision
They are therefore cancer promoting genes
What part of the cell cycle are oncogenes involved in?
G1
What does a ‘gain in function’ of oncogenes result in?
Cancer
How many oncogene alleles must be affected before cancer occurs?
One
What are the three mechanisms in which proto-oncogenes become oncogenes?
Mutation
Chromosomal translocation
Increased protein expression
What testing method is used to screen for mutated oncogenes?
PCR
What cancer/condition is associated with the ABL gene?
Chronic myeloid leukaemia
What cancer/condition is associated with the c-MYC gene?
Burkitt’s lymphoma
What cancer/condition is associated with the n-MYC gene?
Neuroblastoma
What cancer/condition is associated with the BCL-1 gene?
Follicular lymphoma
What cancer/condition is associated with the RET gene?
Multiple endocrine neoplasia
What cancer/condition is associated with the RAS gene?
Pancreatic cancer
What cancer/condition is associated with the HER2 gene?
Breast cancer
Ovarian cancer
What are tumour suppressor genes?
They are genes which normally control the cell cycle
What part of the cell cycle are tumour suppressor genes involved in?
S phase
What occurs when there is a ‘loss of function’ in tumour suppressor genes?
Cancer
How many tumour suppressor alleles must be affected before cancer occurs?
Both alleles
What chromosome is p53 located on?
17p
What is the function of p53?
It is thought to play a crucial role in the cell cycle, preventing entry into the S phase until DNA has been checked and repaired
What cancer/condition is associated with p53 mutations?
Li-Fraumeni syndrome
What is Li-Fraumeni syndrome?
It is a rare disorder that significantly increases the risk of developing several types of cancer
What five cancers are most commonly associated with Li-Fraumeni syndrome?
Breast cancer
Colon cancer
Lung cancer
Sarcoma
Leukaemia
What cancer/condition is associated with APC mutations?
Colorectal cancer
What cancer/condition is associated with BRAC1 & 2 mutations?
Breast cancer
Ovarian cancer
What cancer/condition is associated with NF1 mutations?
Neurofibromatosis
What cancer/condition is associated with Rb mutations?
Retinoblastoma
What cancer/condition is associated with WT1 mutations?
Wilm’s tumour
What cancer/condition is associated with MTS-1 and p16 mutations?
Melanoma
What are DNA damage response genes?
These are the genes that are involved in coding for one of the key enzymes involved in repairing DNA when it is damaged
What part of the cell cycle are DNA damage response genes involved in?
S phase
What occurs when there is a ‘loss of function’ in DNA damage response genes?
Cancer
