WEEK 12 (Cancer) Flashcards
How can cancers vary?
- Ages of onset
- Growth rates
- Invasiveness
- Prognosis
- Responsiveness to treatment
What properties do all cancer cells share?
- PROLIFERATION = abnormal cell growth and division
- METASTASIS = defects in the normal restraints that keep cells from spreading and colonising other parts of the body
What is Neoplasia/Neoplastic progression and what are its properties?
- Uncontrolled, monoclonal proliferation of cells
- Can be benign or malignant
- Any neoplastic growth has two components: PARENCHYMA (neoplastic cells) and SUPPORTING STROMA (non-neoplastic)
Describe the stages from Normal cells to Metastasis
1) NORMAL CELLS - basal -> apical polarity
2) DYSPLASIA - Loss of uniformity in cell size and shape (PLEOMORPHISM), Loss of tissue orientation, Nuclear changes
3) CARCINOMA IN SITU/PREINVASIVE - Irreversible severe dysplasia that involves the entire thickness of the epithelium but does not penetrate the intact basement membrane
4) INVASIVE CARCINOMA - Cells have invaded basement membrane using collagenases and hydrolyses, Cell-cell contacts lost by inactivation of E-cadherin
5) Spread to distant organs via lymphatics or blood
What is Metastasis?
When tumour cells from a primary site invade and migrate to other parts of the body
What happens during metastasis?
1) Invasion
2) Intravasation
3) Transport
4) Extravasation
5) Metastatic colonisation
What makes metastasis complicated?
A tumour is not viewed as an isolated mass of cancer cells but as a tissue that RECRUITS and RECEIVES SIGNALS from surrounding normal cells (TUMOR MICROENVIRONMENT/TUMOR ASSOCIATED STROMA)
What affects the ability of a primary tumor to metastasise?
- Interaction of tumor cells with the tumor microenvironment
- Subpopulation of cancer stem cells in a primary tumor
What is Metastatic colonisation?
The establishment of a progressively growing tumor at a distant site involving the formation of new blood vessels as an essential process to provide nutrients and oxygen
__________________ identifies the last, and often rate-limiting step of metastasis that can be targeted to halt the complete clinical cancer phenotype
Metastatic colonisation
What are the properties of Micrometastases?
- Metastasised tumour cells that do not expand and remain dormant for years
- Maintain overall balance between proliferation and apoptosis
- Do not demonstrate progressive growth
What are the two defining features of stem cells?
- Ability to self-renew
- Ability to give rise to committed progenitors of differentiated cell types of one or more cell lineages
The feature of self-renewal is shared with stem cells and tumor cells. What proposals have been brought out by this?
- Self-renewal provides increased opportunities for carcinogenic changes to occur
- Altered regulation of self-renewal directly underlies carcinogenesis
What is differentiation dependent on?
The expression of a specific subset of genes that defines a particular type of cell
What is Burkitt lymphoma?
A B-cell tumour of the jaw that has an unusual geographical distribution. Occurs in Adolescents or young adults.
CAUSE:
MYC PROTO-ONCOGENE is translocated from its normal position at 8q to a position distal to the immunoglobulin heavy chain locus at 14q
COMMENTS:
- “star sky” appearance (sheets of lymphocytes with interspersed “tingle body” macrophages)
- Associated with EBV
- Jaw lesion in endemic form in Africa
- Pelvis/Abdomen in sporadic form
SYMPTOMS:
- Tumours of jaw/other facial bones
- If spread to CNS -> nerve damage, weakness or paralysis
- Loss of appetite
- Weight loss
- Fatigue
- Night sweats
- Unexplained fever
