Cancer Flashcards
What is cancer?
Arises when normal cells are transformed into malignant ones
What marks cancer?
Marked by uncontrolled cell proliferation and resistance to apoptosis
What is carcinogenesis?
Generation of cancer
Linked to mutagenesis
What is mutagenesis?
Production of a change in DNA sequence
What are the histologies of cancer?
Metaplasia, hyperplasia, dysplasia, neoplasia, metastases
Describe metaplasia
Change in cell type, can be result of injury, develop into dysplasia
- squamous to columnar epithelium in oesophagus
Describe hyperplasia
Increased number of cells, normal cellular appearance, reversible
- benign prostatic hyperplasia
Describe dysplasia
increased proliferation
change in nuclei, loss of tissue architecture
Describe neoplasia
malignancy, no physiological control, irreversible
Describe metastases
spread to different parts in the body
What are the hallmarks of cancer?
Capabilities to promote growth of malignancy
Give examples of self sufficient growth signals
Constitutively active receptors (EGFR), proteins downstream of growth factor signaling (RAS-RAF-MEK pathway)
What is the EGFR pathway?
Epidermal growth factor binds to epidermal growth factor receptor
- stimulates downstream pathway to drive cellular proliferation
- change in gene expression transcription
How do cells evade apoptosis?
Resistance through loss of p53 activity or overexpression of anti-apoptotic Bcl2
What is Bcl2?
Family of apoptotic inhibit enzymes for apoptosis
Why do tumours need blood vessels?
Requirement for tumours to increase significantly in size
How do cancer cells bind to new environments?
Cell adhesion molecules (CAMs) and integrins
How do cancer cells produce ATP/energy (cancer cell metabolism)?
Malignant cells produce ATP by glycolysis and lactate fermentation
What is lactate fermentation in cancer cells?
Lactic acid burn from big tumours
Why do cancer cells switch to anaerobic glycolysis?
Tumours are hypoxic: adaptation to lack of oxygen
AKT pathway activation and p53 activation
What are the forms of cancer?
Carcinoma, sarcoma, leukaemia, lymphoma, melanoma
What is carcinoma?
Originate from epithelial cells
What is sarcoma?
Originate in bone and soft tissue (connective tissue), muscle and fibrous tissues
What is leukaemia?
Cancers of white blood cells, invasive
What is lymphoma?
Malignancy of lymphocytes, lymph nodes
What is melanoma?
Originate from melanocytes, skin pigment
How are defects inherited?
Defects in cell must be genetic or epigenetic
Affect proteins they encode
What are the types of mutations?
Inherited, spontaneous, induced
Explain inherited mutations
Associated with familial history of cancer
- BRCA1 mutations
- Lynch syndrome (colorectal)
What is aneuploidy in spontaneous mutations?
Change in chromosome number
Failure to repair errors in replication
Explain induced mutations
Environmental exposures
- UV light induces formation of thymine dimers
What is an exon?
Region of genome that ends up within an mRNA molecule
What is an intron?
Non-coding sequence of RNA transcription
What are the two types of genetic change?
Transition and transversion
What is transition?
Base is still a purine or still a pyrimidine
Guanine -> Adenine
Cytosine -> Thymine
What is transversions?
Change from purine to pyrimidine or backwards
Thymine -> Guanine
In what cancer are chromosomal changes common?
Leukamia
What genes are mutated in cancer?
Oncogenes, tumour supressor genes
What are oncogenes?
Capable of initiating cancer formation when activated
Drive abnormal cell proliferation
What are tumour suppressor genes?
Suppress abnormal growth and carcinogenesis
Implicated in regulation of cell cycle, apoptosis and DNA repair
What is the most frequent mutated gene?
TP53 has a crucial role in DNA damage
