F1 Flashcards
What are the two main characteristics of cancer cells?
What is a defining feature of cancer cells?
- reproduce despite normal constraints that inhibit cell proliferation and clonal expansion.
Normally a cell only divides following growth factor or hormones - Cancer cells invade and colonize territories normally reserved for other cells.
defining feature of cancer cells: Autonomous/deregulated cell growth
What is cancer caused by? What are the changes that this can result in?
Cancer is caused by the accumulation of genetic alterations that confer a survival advantage to the cancer cell.
Changes may result in:
- increased cell growth
- resistance to apoptosis
- altered tissue invasiveness
- angiogenic proliferation
- ability to escape immune surveillance
Molecular medicine: caner
What does the genetic nature of cancer suggest?
The genetic nature of cancer is reflected in the clonal nature of the cancer cells.
i.e daughter cells inherit the properties of the mother cell.
- Recognition that cancer is a genetic disease has lead to intensive effort to characterise genes responsible which has lead to new therapies
Characteristics of cancer cells.
What is cell transformation?
The change from a normal cell to a cancer cell is called cell transformation.
cancer cells do not look like normal cells
the pathologist uses the change in the appearance of the cell to diagnose the cancer.(where it originated from)
What are the characteristics of cancer cells? and what has research shown regarding genetic mutations in cancers?
Cancer cells:
- enlarged nucleus
- changes to the cytoskeleton
- loss of specialised features
spectrum in the changes in the appearance of the cancer cell
some highly malignant cancers it is nearly impossible to tell the cell of origin
much data to suggest as cancer develops
accumulation in genetic errors means increased change in cell appearance
Benign tumours
Appearance under the microscope like the tissues they came from
Remain localised and do not spread (encapsulated in fibrous capsule. do not change in size)
Usually do not cause problems unless they grow in a confined space. (e.g the brain)
Malignant tumours (6 or more major genetic errors)
- Do not resemble the tissue of cell origin
- often have irregular structures, large variable nucleus, little cytoplasm, evidence of mitosis (rapidly), little specialised features
- invade surrounding tissues
How are cancer cells different from normal cells?
- malignant cells are all members of a single clone, including cells that have spread to distant sites.
- Cancer cells appear different than surrounding normal cells, divide at a faster rate, have a high metabolic rate, invade new tissues.
Spread of Cancer: Metastasis
What is metastasis
and what determines spread of cancer?
Cancers invade other tissues and spread to other parts of the body - METASTASIS
Metastasis can be local or distant
Spread of cancer may depend on the type of cancer i.e some more likely to spread than others
e.g small cell lung cancer metastatic at time of patient presentation
DNA damage causes cancer
Cancer cells develop due to damage to the cells DNA.
DNA damage can be: inherited (germ line errors) or acquired (somatic errors)
In inherited cases every cell in the body carries one copy of DNA with that genetic defect (germ-line mutations)
Acquired somatic errors
As a person gets older the number of DNA mutations increases therefore increased risk of cancer.
Acquired mutations in a cell may eventually lead to cancer in that tissue
For somatic mutations, only the cancer cells carry the DNA mutation/error.
what are carcinogens and some examples
Compounds or chemicals that produce cancer
Carcinogens include:
- UV light
- tobacco smoke
- meat preservatives
- ionizing radiation
What cells susceptible to DNA damage?
what is it about some cells that make them susceptible to DNA damage? and why
- Rapidly dividing cells are particularly susceptible to genetic damage and cancer
- In somatic cells that divide frequently (such as bone marrow, gut cells, skin cells etc), carcinogens cause DNA damage causing mutation of one base to another
WHY
- DNA repair enzymes correct these errors, however if they are:
- substantial mutations
- loss of DNA repair enzymes
- less time for the DNA repair mechanisms
therefore an accumulation of DNA mutations occurs.
There is less time for DNA repair in rapidly dividing cells, cancer cells - more rapid cell cycle, gradually accumulate more and more genetic damage
What types of cancers do we have familial aggregation?
Familial aggregation occurs in virtually every type of human cancer
What is some familial aggregation due to?
- shared exposure to carcinogens
- genetic predispositions
- combinations of both
Person who has a parent or sibling who develops cancer at a young age has 2 times the risk of developing the same cancer
