Ch 10- Biology of Cancer Flashcards
what is cancer?
the leading cause of suffering and death in the world, a collection of more than 100 different diseases, each caused by a specific and often age related accumulation of genetic and epigenetic alteration. Environment, heredity and behaviour interact to modify risk of developing cancer and response to treatment.
what does epigenetic mean?
study of how behaviours and environment cause changes that affect gene function
what does neoplasm mean?
a new/abnormal growth
what is a benign tumour?
encapsulated and contain well-differentiated cells/ well organized stroma. Retain normal tissue structure/don’t invade beyond capsule. Can still be dangerous/benign meningioma at base of skull can compress local brain tissue
what is a well differentiated tumour?
cells and tissue structures that are like normal tissues and tend to grow and spread slowly
what is an undifferentiated tumour?
made up of cells that look very abnormal and often grow and spread quickly
what is a malignant tumour?
- they progress to cancer.
- rapid growth rates/abnormal organization
- hallmark of cancer: anaplasia= loss of cellular differentiation= undifferentiated
- pleomorphic: variability in size and shape
- large stroma but disorganized with abnormal structure
- metastasis: ability to spread far beyond tissue of origin/ most deadly characteristic of malignant tumours
what is a carcinomas?
cancers arising from epithelial tissue
what is a adenocarcinomas?
cancers arising form ductal or glandular structures
what is a carcinoma in situ?
- preinvasive epithelial tumours of glandular or squamous cells origin
- cancers develop incrementally as they accumulate specific genic lesions
- they have not broken through basement membrane or invaded surrounding stroma therefore not considered malignant
- they vary from low-grade to high grade dysplasia (abnormal growth)
- high grade lesions have highest likelihood of becoming invasive carcinoma
what are the 3 fates of CIS?
- remain stable for a long time
- progress to invasive/metastatic cancers
- regress and disappear
what does situ mean?
in natural or original place
where does mutation come in for cancer?
multiple mutations are required before cancer can develop
- cell aquires characteristics that provide advantage over neighbouring cells
- common advantages: increased growth rate and/or decreased apoptosis
what is the result of mutations in cancer cells?
- decreased need for growth factors to multiply
- lack contact inhibition
- anchorage independence to disseminate through body (metastasis)
- immortality: no apoptosis
what are the two fundamental cancer concepts?
- cancer is a genetic disease arising from multiple mutations
- The tumour microenvironment is a mixture of cells (cancerous and benign) as well as their secretion
what is the stage 1 of cancer?
tumour initiation: producing initial cancer cell/ first stage of cancer development/ dependent on specific mutations
what is stage 2 of cancer?
tumour promotion: population of cancer cells expands with diversity of phenotypes/additional mutations
what is stage 3 of cancer?
tumour progression: spread of tumour to adjacent (invasion) and distal sites (metastasis)/ governed by more mutations and changing microenvironments
what is a small scale mutation?
point mutations: alteration of one or a few mucleotide base pairs/can have prodound effects on activity of resultant proteins
what are some types of point mutations?
Driver mutations: mutations that “drive” progression of cancer
Passenger mutations: mutations that don’t contribute to malignant phenotype. some are just random events and referred to as “passenger mutations”
what are large scale mutations
- Chromosome translocations: large changes in chromosome structure. section of one chromosome is translocated to another chromosome
- gene amplification: instead of normal two copies of gene, tens or even hundreds of copies are present
what is the clonal proliferation model?
selective advantage cancer cell has over neighbouring cells/it can replicate faster than non-mutant neighbours
- increasingly rapid cell division and impaired DNA repair mechanisms of cancer cells= continuing accumulation of mutations throughout progression to most aggressive metastatic lesion
what does tranformation mean?
process by which a normal cell becomes a cancer cell
what is transformation directed by?
progressive accumulation of genetic changes that alter basic nature of cell and drive it to malignancy
what is the result of mutations?
- genomically heterogeneous mixture of cells
- where subsets accumulate more and more mutations which increases cell’s malignant potential
how are cells similar to wound healing?
because initial cancer cell proliferation triggers a typical proinflammatory response by itself and adjacent nonmalignant cells
- as with wound healing, mediators recruit inflammatory or immune cells and cells associated with tissue repair
what happens when there is abnormal wound healing?
- recruited cells form a stroma
- stroma surrounds and infliltrates tumour/stroma cells can make up 90% of tumour mass
- stroma growth not just affected by rapid cancer cell proliferation but also various cell additions to stroma
- extensive paracrine signaling among stromal and cancer cells affects both populations
what is the effect of abnormal wound healing?
- cancer cells increase proliferation and become more heterogeneous
what is the process of abnormal wound healing?
= great deal of cancer cell death
- surviving cells are more aggressive
- many take on a metastatic phenotype
WHICH MECHANISM?
Cancer cell: I need the ability of uncontrolled growth
Sustained proliferation signals
- Pro-oncogene control this
- Oncogene= mutations
- Result: blocking of body’s mechanism to stop uncontrolled growth
