Carcinogenesis Flashcards
(23 cards)
What are the three common characteristics of all cancers
It is a genetic disorder caused by DNA mutations
Genetic alterations in cancer cells are transmitted to daughter cells
Mutations and epigenetic alterations give cancer cells hallmarks
Name some of the hallmak=rks of cancer
Self sufficent in growth signals, insensitive to inhibitory ones
Evasion of apoptosis and limitless reproductive potential
Systained angiogenesis and altered cell metabolism,
Evasion of immune surveillance, and evasion and metastasis
What ccancers can ionising radiation lead to
Acute and chronic myeloid leukaemia, papillary carcinoma of thyroid
What cancers can non-ionising radiation cause (UVB, sunlight)
Squamous cell carcinoma, basal cell carcinoma, malignant carcinoma of skin
What are oncogenes
Cells which control growth and differentiation
What different types of oncogenes are there
Proto-oncogenes: FOr cell growth and differentiation
Growth factor/growth factor receptors (these induce cell growth)
Signal transducers: relay receptor activation to nucleus
Cell cycle regulators mediate progression though the cell cycle
What do tumour supressor genes do
Regulate cell growth, decrease risk of tumour formation
notable examples are p53 and retinoblastoma
What does p53 do
Tumour supressor gene,
regulates cell cycle and DNA repair, papoptosis. Can be damaged by mutation or loss of alleles.
What is the knudson two-hit hypothesis
Both copies of the gene must be knocked out for tumour formation (such as with p53)
At what point is p53 active in the cell cycle
During G1 checkpoint, if DNA is found to be damaged, p53 gene is activated, preventing access to S phase, arresting the cell cycle
Describe the cell cycle in order
G1 -> S -> G2 - > M -> G1
What other Tumour supressor gene acts like p53
Rb
What do apoptosis regulators do
prevent apoptosis in normal cells but promote ti in mutated cells with un-repairable DNA
How does BCL2 and cytochrome C regulate apoptosis
BCL2 stablises mitochondrial membrane, blocking cytochrome C release. Disruption og BCL2 allows cytocchrome C to leavemitochondria and activate apoptosis.
Follicular lymphoma gets around this
What is telomerase and what happens woth cancers
They shorten with serial cell divisions, eventually causing senescence.
Cancer cells show upregulation of telomerase
What is angiogenesis and how is it linked to cancers
The new blood vessel formation is needed for tumour survival and growth. Cancers usually produce fibroblast growth factor and vascular endothelial growth factor, both angiogenic, responsible for blood vessel creation
What is dysplasia?
disordered cell growth, often precancerous cells.
Theoretically reversible with removal of stressor. Otherwise can progress to irreversible carcinoma
What is neoplasia
Unregulated, clonal, irreversible growth. Neoplastic tumours can be benign or malignant
What are the characteristics of a benign tumour
Remains localised, slow growing, closely resembles tissue from which they grow, often circumscribed or encapsulated
What are the characteristics of malignant tumours
Invades surrounding tissues, many can metastasize. Often rapidly growing, varies in resemblance to tissue of origin, irregular margin
What is the difference between in situ and invasive carcinoma
In situ means an epithelial neoplasm exhibiting all cellular features of malignancy, but hasnt invaded through the epithelial basement membrane, separating form potential routes of metastasis
What are some characteristic signs of malignanct cells
Increased nuclear/cytoplasmic ratio
Nuclear pleomorphism and hyperchromasia
Irregular chromatin distribution, prominent nucleoli
Irregular nuclear membranes
Name characteristics of benign cells
Low nuclear to cytoplasmic ratio
All nuclei of similar size, not hyperchromatic, vesiclular, evenly distributed chromatin, smooth nuclear membranes
