Angiogenesis Flashcards
What is the non-neoplastic element of a neoplasm?
Stroma
What does the stroma contain?
Blood vessels to supply nutrients to the tumour
Fibroblasts
Variety of inflammatory cells
What is continued growth of a tumour dependent on?
An adequate blood supply to provide oxygen and nutrients
It also allows tumour cells to gain access to the vessels and the development of metastasis
What happens to a tumour if it does not have an adequate blood supply?
Necrosis
What are the roles of the two types of tumour associated macrophages?
M1 - primarily tumoricidal = fight tumour growth
M2 - help tumour growth
What is metastasis?
Transmission of microorganisms or cancerous cells from an original site to one or more sites elsewhere in the body, usually by way of the blood vessels or lymphatics
Describe the 4 stages of metastasis
- Intravasation - digestion of basement membrane
- Tumour cells must evade the immune system by forming small clusters
- Extravasation - invade a basal lamina, grow, form blood vessels
- Extravascular tumour
Compare the main features of benign and malignant tumours
Benign - slow growth, demarcation, resembles original architecture
Malignant - fast growing, invades locally, metastasis, anaplasia, resembles original architecture
What are carcinogenic agents, give some examples
Agents which cause tumours - cause malignant transformation in cells
- Chemicals, irradiation, infectious agents
What is an oncogene?
Drives neoplastic transformation in the organism
What is a proto-oncogene?
A normal cellular gene that regulates cell cycle activation
How are oncogenes activated?
- By viral-oncogenes - present in the viral DNA/RNA, infection with these leads to an oncogene
- DNA damage or mutation of a proto-oncogene
Carcinogens are electrophiles, what is an electrophile?
Structures that are have electron deficient atoms
What 2 steps are undertaken by chemical carcinogens?
Initiation - Carcinogens introduce an irreversible change
Promotion - the damaged DNA template must be replicated so that the change in DNA becomes fixed
What are promotors?
Agents that stimulate the division of mutated cells
Give an example of a promotor
Oestrogen binding to cell receptors, stimulates growth of neoplasms in humans
What is radiation?
Energy that travels in the form of waves
What are the two types of radiation?
Non-ionising: Not enough energy to displace bound electrons from atoms
Ionising: Sufficient energy to release electrons in a reaction cascade
What are the consequences of high or low doses of radiation?
High - extensive necrosis affecting more rapidly dividing cells
Low - accumulative effects, DNA damage, apoptosis, tumours
Which types of non-ionising radiation has a direct action on DNA?
UVB
Give some examples of
DNA virsuses
Papovavirus
Herpesvirus
Adenovirus
Describe a viral DNA malignant neoplasm
Viral genome is integrated into the host genome, only part of the viral cycle is completed
- suppression of hosts immune system
- activation of cellular oncogenes
What is the role of tumour suppressor genes?
Normal cellular genes that regulate cell cycle activation
- control cell cycle, apoptosis and DNA repair throughout the cell cycle
