Chapter 10 - Biology of Cancer Flashcards
How is cancer a form of Darwinian evolution?
tumour development has cells with a heritable change that have a survival advantage, so outcompete their neighbours
What is the leading cause of suffering and death worldwide?
cancer
Cancer is a collection of more than ___ diseases
100
Is cancer age related?
yes, the longer we live, the greater chance DNA replication has a mutation
Is cancer genetic or epigenetic?
it can be both
Epigenetic
how behaviours and environment cause changes that affect gene function
What 3 factors influence risk and development of cancer?
environment, heredity, behaviour
Cancer is derived from the Greek work Karinoma meaning ____. Why?
crab; describes the projections of the tumour into near tissues
Original Tumour Definition
any swelling caused by inflammation
Current Tumour Definition
new growth or neoplasm (abnormal growth)
Are all tumours cancer?
no
Benign Tumour
non-cancerous
Malignant Tumour
cancerous
Well-differentiated Cells
normal tissues that grow and spread slowly
Undifferentiated Cells
made of abnormal cells that grow and spread quickly
What kind of cells do benign tumours have?
well-differentiated cells and connective tissue
Do benign tumour invade beyond its capsule?
no, they maintain a normal structure
Are benign tumours dangerous?
they can be
Benign Meningioma
tumour at the base of the skull that can compress the brain
Malignant tumour progress to ____
cancer
Malignant tumours grow ______ and have ______ organization
rapidly; abnormal
Anaplasia
loss of cellular differentiation
What type of cells do malignant tumours have?
undifferentiated
Pleomorphic
variability in size and shape
Stroma
supporting structure
Metastasis
ability to spread far beyond tissue of origin
What is the most deadly characteristic of malignant tumours?
metastasis
Carcinomas
cancers arising from epithelial tissue
Adenocarcinomas
cancers arising from ductal or glandular structures
Do benign tumours metastasize?
no
Benign tumours have a ____ mitotic index, malignant tumours have a _____ mitotic index
low; high
What is a carcinoma in situ (CIS)?
a pre-invasive epithelial tumour of glandular or squamous cell origin
What does “pre-invasive” mean?
the cancer develops incrementally as it accumulates specific genetic mutations
Are CIS considered malignant?
No, they have not broken the basement membrane or invaded surrounding stroma
Situ
in natural or original place
CIS remain _____ for a long time
stable
Can CIS progress?
yes they can progress into invasive or metastatic cancers
Can CIS disappear?
yes they may regress
CIS either…
remains, progresses, disappears
How to classify CIS?
vary from low-grade to high-grade
Which class of CIS are more likely to become an invasive carcinoma?
high-grade
Cancer is predominantly a disease of ______
aging
Mutation
cancer cells acquire characteristics that provide them an advantage over other cells
What is the advantage of cancer cells mutating?
increased growth rate and/or decreased apoptosis
Do cancer cells need growth factors to multiply?
no
Cancer cells lack contact inhibition meaning…
Anchorage independence
Do cancer cells undergo apoptosis?
no, they are immortal
How many mutations are required for cancer cells to form?
multiple
Tumour Microenvironment
mixture of cells (cancerous and not) and their secretions
Stage 1 of Cancer: Tumour Initiation
production of initial cancer cells, first stage of development
What does tumour initiation depend on?
specific mutations
Stage 2 of Cancer: Tumour Promotion
population of cancer cells expands with diverse phenotypes, the cells undergo additional mutations
Stage 3 of Cancer: Tumour Progression
tumour spreads to near (invasion) and far (metastasis), more mutations occur
Point Mutations
small-scale genetic changes, alteration of one or a few base pairs
Translocations
large-scale genetic changes
Driver Mutations (small-scale)
drive the progression of cancer forward
Passenger Mutations (small-scale)
don’t contribute to malignant phenotypes, just random events
Chromosome Translocations (large-scale)
large changes in chromosome structure
During chromosome translocation…
a section of one chromosome is translocated to another
Gene Amplification (large-scale)
rather than 2 normal gene copies, tens or hundreds are made
HER2 Proteins
too many receptors signalling cells to grow and divide too quickly
Clonal Proliferation Model
advantage of cancer cells that causes them to replicate faster than neighbours
What drives the accumulation of mutations?
rapid cell division and impaired DNA repair mechanisms
What does inactivation of the antigen presenting cell cause?
the cell seems normal but proliferates excessively
What does the mutation that activates K-ras cause?
normal cell that proliferates too much
What does a loss of DCC and an over-expression of COX-2 cause?
rapidly proliferating cell undergoing structural changes
What does a loss of TP53 and the activation of telomerase cause?
uncontrollable abnormal cell growth
Transformation
process by which a normal cell becomes a cancer cell
What directs transformation?
accumulation of genetic changes that drive it to malignancy
Do all cancer cells have the same mutations?
not necessarily, some have their own set of mutations
What is the result of transformation?
heterogenous mixture of cells that accumulate more and more mutations
Heterogenous
diverse in character
Which cancer cell triggers the initial pro-inflammatory response?
the initial cancer cells
Who is affected by the initial pro-inflammatory response?
the cancer cells that triggered it and the neighbouring nonmalignant cells
What is recruited during the pro-inflammatory response?
-Inflammatory and immune cells (macrophages, T and B cells)
-tissue repair cells (fibroblasts, adipocytes, mesenchymal stem cells, endothelial cells)