Neoplasia Flashcards
(39 cards)
What is Neoplasia?
An abnormal new mass of tissue, with unregulated and uncoordinated cell growth
How does neoplasia occur?
proliferation of existing cells
What are the types of neoplasia?
Benign - doesn’t produce any problems unless its in a vital area e.g. brain
Malignant - immortalized clone, loss of cell regulation
Biology of tumour growth
Normal growth - polyclonal growth, well regulated
Hyperplasia - excessive polyclonal growth
Not cancerous but may progress to cancer in later years
Benign tumours - clonal proliferation, limited response to cell signal
Malignant tumours - immortalized clone, loss of cell regulation
Leiomyoma
benign tumour of smooth muscles
Lipoma
benign tumour of fat cells
Angioma
benign tumour of blood vessel
Adenoma
benign tumour of a gland
Fibroma
benign tumour of fibroblast
Characteristics of malignant tumours
Anaplasia or cellular atypia: Lack of differentiation
1) variation in shape and size of cells or nuclei
2) Enlarged + hyperchromatic nuclei, prominent nucleoli, increase nuclear to cytoplasmic ratio
Increased and abnormal mitotic activity (especially metaphase)
Dysplasia: disorganised and random growth
Invasion: direct extension and penetration by cancer cells into neighbouring tissues
Metastasis: spread of cancer cells through thecirculatory systemor thelymphatic systemto more distant locations.
Principal characteristics of carcinomas and sarcomas
printed table
What are the hallmarks of cancer?
- Self sufficiency in growth signals
- Insensitivity to anti-growth signals
- Tissue invasion & metastasis
- Limitless replicative potential
- Sustained angiogenesis
- Evading apoptosis
Initiators of cancer development
Initiation is the first step in the two-stage model of cancer development.
Initiators cause irreversible changes (mutations) to DNA (DNA damage) that increase cancer risk.
e.g. chemicals, viruses, radiation
Promoters of cancer development
Promotion is the second step in the two-stage model of cancer development.
Once a cell has been mutated by an initiator, it is susceptible to the effects of promoters. e.g. growth factors, hormones (estrogen plays an important role in progression of steroid hormone-dependent cancers)
What are the key three genetic events involved in the conversion of a normal cell into a neoplastic cell?
- Telomerase expression preventing telomeric shortening with each cell division and thwarts cell aging.
- Inactivation of tumour suppressor gene function in the immortalized cells removes inhibition of growth.
- Oncogenes activation sets up autocrine growth stimulation
Define Proto-oncogenes
Normal genes - positively regulate the cell cycle and help cells to grow.
Define oncogenes
Mutations may cause proto-oncogenes to become oncogenes, disrupting normal cell division and causing cancers to form
Neoplastic growth - promoting factors
Oncogenes
Anti-apoptotic genes
Telemorase expression
Epigenetic contributions
Neoplastic growth - inhibiting factors
Tumour suppressor genes
Pro-apoptotic genes
Role of oncogenes in cancer
What is gain-of-function mutation?
When a proto-oncogenes causes cancer after mutation occurs in the gene that results in the gene being permanently turned on.
aka dominant mutations - only one copy of the gene needs to be mutated in order to encourage cancer
Role of p53 in tumour development
Mutation causes P53 can lose its normal function.
Therefore does not arrest the cell cycle and damaged cell continues to divide - may result in cancer.
What is the role normal p53?
When cellular damage occurs, P53 arrests the cell cycle (before S phase) until the damage is repaired.
If damage cannot be repaired, apoptosis occurs.
What is the role of normal pRB?
Binding of Rb, converts E2F factors from transcriptional activators to transcriptional repressors.
