Topic 1 - Cancer Flashcards
Cause and mechanism (37 cards)
What is cancer?
A group of diseases that includes solid tumours at almost any site in the body, and leukaemias. A disease of the body’s own cells.
What causes cancer?
Uncontrolled division of abnormal cells in a part of the body
What are the features of cancer at a cellular level?
- uncontrolled cell division
- change in morphology
- dedifferentiation of cells
- cell mitigation into adjacent and distal tissues
What are the characteristics of cancer cells grown in lab?
- Uncontrolled growth
- Loss of contact inhibition
- Immortal
What are the stages of cancer development?
- Normal cells
- Hyperproliferative cell population
- Early adenoma
- Late adenoma
- Carcinoma
What is hyperproliferation?
An abnormally high rate of proliferation of cells by rapid division; substantial overproliferation
What is adenoma?
A benign tumour formed from glandular structures in epithelial tissue.
What are the steps of cancer development at a cellular level?
Normal cells Mutation Proliferation Mutation Rapid growth Tumour Mutation Malignant tumour Mutation Enters blood stream Metastatic tumour
What are the common genetic abnormalities?
- Point mutation
- Deletion
- Insertion
- Gene amplification
- Chromosomal translocation
- Aneuploidy
What can point mutations result in?
- A change in gene function
- Amino acid substitution
- Introduce a stop codon early
What can insertions and deletions result in?
- Gain or loss of one or two bases results in a shift in the reading frame of a gene transcript
- Frameshift mutation
What can gene amplification result in?
-A cell having anywhere up to 100 copies of a gene it would normally have 2 of
What can chromosomal translocations result in?
- Genes being moved to a more transcriptionally active site of the chromosome
- Two genes being recombined into a new gene fusion
What can aneuploidy result in?
-Any departure from the normal structure or number of chromosomes
What are the two things mutations can do to genes?
- Disrupt the coding sequence sufficiently to stop protein product from functioning normally
- Make the protein more active by improving the amino acid sequence, or by allowing more copies to be made
What does genetic instability caused by carcinogens/mutations lead to?
Genetic variation in populations of tumour cells for natural selection to work on
What does mutation induction require?
- Chemical modification of DNA
- Replication of DNA
- Resulting in misincorporation of DNA by polymerase
What induces normal cells to divide?
+ve growth factors
What prevents normal cells from dividing?
-ve growth factors
What is apoptosis?
The death of cells which occurs as a normal and controlled part of an organism’s growth or development
What are the characteristics of normal cells?
- Induced to divide by +ve growth factors
- Prevented from dividing by -ve growth factors
- Finite life span
- Self-destruct by apoptosis
- No influence on blood vessel formation
- Tightly joined and immobile
- Genetically stable
What are the hallmarks of cancer cells?
- Genetic instability
- Invasive and metastatic
- Independent of +ve growth factors
- Resistant to -ve growth factors
- Immortal
- Resistant to apoptosis
- Angiogenic
What is Angiogenesis?
The formation of new blood vessels
What are oncogenes?
Mutated versions of normal genes that have a key role in promoting growth and division of cells - mutations lead to increased activity/inappropriate switching on of cell division
