Neoplasia Flashcards
atrophy
an acquired diminution of growth due to a decrease in the size or number of constituent parts (cells) of a tissue eg. decrease in size of ovaries post menopause
Hypertrophy-
increase in the size of individual cells, in response to prolonged demand for increased function eg. pregnant uterus
Hyperplasia-
increase in the number of the component cells- increase proliferation, only lasts as long as the cause eg. lactating breast
competence factor
any factor that causes the cell to enter the cell cycle from G0
commitment factor
factors like polypeptide growth factors & hormones that pushes the cell through G1/S (restriction checkpoint)
2 protein families that affect the entry of cells to the next stage:
- cyclin dependant kinases (CDKs)
- cyclins- concentrations rise and fall regularly throughout cell cycle
points of cell cycle where cyclins are synthesised in the greatest concentration
- G1 cyclins: cyclin Ds
- G1/S: cyclin Es
- S cyclins: cyclin As
- M cyclins: cyclin Bs
3 options a cell can commit itself to in G1:
- recycle and go through the cell cycle another time
- decycle and enter a resting G0 phases where it can re-enter the cycle if conditions demand
- decycle permanently and terminally differentiate
what protein controls the restriction checkpoint?
Rb
E2Fs
transcription factors that bring about own transcription and of the cyclin E- CDK2 complex + regulate other genes that promote entry into the S phase
how does Rb inhibit cell progression and force it into G0?
Rb binds to E2Fs and inhibits them by binding to E2F responsive promoters. Once the Rb-E2F complex is bound, it recruits histone deacetylases and chromatin remodelling complexes. The remodelling and removal of the acetyl groups repress the action of the promoters
why does phosphorylation of Rb allow cells to move onto the S phase?
a certain level of phosphorylation stops Rb from being able to bind to E2Fs
what complex increases the phosphorylation of Rb?
cyclin E-CDK2 complex
purpose of G2/M checkpoint
checking that the cell has replicated all of its DNA and completed any necessary DNA repair
purpose of spindle checkpoint
whether chromosomes are all attached properly so that segregation in anaphase goes correctly
permanent cells
irreversible differentiated, eg. neurones, striated myocytes
constituents of the continuously self renewing population
- Stem cells: self-renewing & slowly proliferating
- Transit amplifying: committed to differentiation and rapid proliferation at same time
- Terminal differentiation: fully differentiated
Metaplasia
replacement of one differentiated cell type by another in response to persistent injury, most commonly involves replacement of a glandular epithelium by a squamous one eg. exposure of bronchial epithelium persistently to tobacco smoke
Dysplasia
part of spectrum of changes of pre-invasive neoplasia, dysplastic changes don’t revert to normal once the injury is removed
morphology in dysplasia
• The regular organised appearance of epithelium is disturbed by variation in shape and size of cells
- Enlargement- increased Nucleus: Cytoplasm ratio
- Irregularity- pleomorphism (variation in nuclear size, shape and chromatin staining)
- Hyperchromatic nuclei (dark nuclei)
- Increased mitosis
• Distortion of the proliferating compartment compared to differentiation compartment
neoplasia
- An abnormal mass of tissue (tumour)
- Growth exceed and is uncoordinated with that of normal tissue
- Persists in same excessive manner after stimulus is removed
- Irreversible
- Composed of living cells
- Cells of a tumour have deregulated or lost the division/ differentiation/death controls which regulate tissue organisation and architecture
invasion
capacity to infiltrate surrounding tissue and organs
Metastasis-
ability to spread to and proliferate in distant parts of body after tumour cells
routes of metastasis
by blood and lymph channels and along body spaces (transcoelomic spread)
Benign neoplasms-
proliferate but do not invade adjacent tissue
Generally, not life threatening but they can cause problems because of position, pressure, obstruction and excess production of hormones.
Malignant neoplasms
proliferate, invade adjacent tissues and/or metastasise, malignant tumours are cancers
morphology of benign tumours
- Slow growing
- Low mitotic rate
- Clearly demarcated from surrounding tissue- encapsulated or pseudo capsule
- Nuclear morphology often near normal, grow outwards
- Clonal mutations or chromosome abnormalities- not aneuploid
morphology of malignant tumours
- Not demarcated (set boundaries) clearly
- Surface often ulcerated and necrotic
- Often grow inwards (endophytic growth)
- Cut surface heterogenous
- Rapid growth
- Nuclei pleomorphic, hyperchromatic
- Abnormal mitoses
- Usually aneuploid
stroma
vascular connective tissue surrounding and supporting the neoplastic cells- very pronounced in carcinomas
why is neovascularisation important?
for growth of tumour
4 most common cancers
breast, lung, colorectal and prostatic cancers
highest levels of mutation
defective DNA repair, UV and smoking
name for preinvasive stage of cervical cancer
cervical intra-epithelial neoplasms (CIN- UK/Europe) or lesions
cytological features of high grade intra-epithelial neoplasms
- Variation in cell size/shape
- Abnormal nuclei (pleomorphism- variability of nuclei & hyperchromasia- excessive pigmentation)
- Abnormal and increased mitoses
- Loss of nuclear polarity
- Loss of differentiation
why have CINs not invaded?
they stay on the epithelial side of the basement membrane- intra-epithelial
breast precursor name
Ductal Carcinoma In Situ (DCIS)
features of ductal carcinoma in situ
excessive numbers of neoplastic epithelial cells (larger than normal with a range of nuclear cytological abnormalities- pleomorphism, hyperchromasia, loss of differentiation- build up within enlarged ducts or groups of small ducts causing them to dilate
in situ
non invasive
large intenstine precursor name
adenoma
adenoma
have dysplastic glandular epithelium, may evolve into an invasive adenocarcinoma (malignant)
polyp
Adenomas of the colon