Cancer Basics Flashcards
What is cancer?
Diseases characterized by abnormal regulation of cell growth and reproduction
___ and ___ lead to unregulated and increased cell proliferation
Damage and changes in gene expression
What do cancer cells compete with normal cells for?
Space and nutrients
Cancers increased population of unregulated cells have the capacity to ___ and ___ others
travel and invade
Name the 2 steps of the cell cycle.
Interphase and mitotic phase
Where are the cell checkpoints and what is their function?
G1(stops duplication if DNA is damaged) and G2(stops cycle if damaged
What are the three parts of interphase?
G1-Cell growth, S-Cell growth and DNA synthesis, G2- Growth and prep for division
What happens during the mitotic phase? What is the breakdown of stages within the mitotic phase?
Split into two identical daughter cells. PMAT(prophase, metaphase, anaphase, telophase)
What does cytokinesis signify?
Complete division
What cells reproduce rapidly? Provide example
Bone marrow or skin cells
What cells never reproduce? Provide example
neurons
For the cells that don’t reproduce, what stage are they thought to remain in?
G0
What is the Retinoblastoma pathway?
A complex signaling system controlling division
Is the RB pathway a major target for human cancer-causing mutations?
yes
Where does the most common mutation occur(in regards to the cell cycle/checkpoints)?
The most common effects the G1 checkpoint via mutation of the RB pathway
What is cyclin D?
A protein which binds to RB protein causing E2F to unbind
When E2F unbinds from RB, what is the result?
Becomes inactivated, allowing it to progress through the cell cycle
What 3 primary mutations can occur at the RB pathway?
1) Mutation can occur on RB, keeping it inactive indefinitely
2) Mutation can occur on transcription factor E2F, causing an under-expression, resulting in inactivation of RB and therefore progression through the cell cycle
3) Over-expression of cyclin D can lead to more inactivation of RB than normal, allowing for the cell to progress through the cell cycle.
Describe the status of RB activation/inactivation and how cyclin D and E2F influence it.
RB is active when E2F is bound to it. Active means that it is not able to pass the G1 checkpoint or continue with the cell cycle. If cyclin D is expressed, it binds to RB, unbinding transcription factor E2F and inactivating the protein. This allows the cell to pass the G1 checkpoint, whether damaged or not, and continue the cycle.
TorF: Any alteration that occurs at the RB pathway which inactivates RB can lead to cancer.
True
What are other possible regulation issues in cancer cells? (There are 4)
1) presence of growth factors
2) Ratio of cell surface area to cell volume
3) Contact inhibition limiting cell growth due to lack of space
4) Cell growth inhibition due to a collection of the cell’s own secretions
What is carcinogenesis?
The process by which a normal cell becomes cancerous
What are the steps of carcinogenesis?
Initiation and Promotion
What is the initiation portion of carcinogenesis?
The carcinogen attacks a normal cell
What is the multiple hit theory?
Two hits are required to mutate a gene. The first hit could be hereditary, in which it was passed down. The first hit could also be due to a rare event (carcinogen). The second hit would be a rare event (carcinogen) in which that gene becomes mutated. Therefore, all daughter cells from this mutated gene will then produce mutated genes.
What is the promotion portion of carcinogenesis?
The gene is expressed within the cell causing uncontrolled division and tumor production
Can a cell have one hit and still be functioning normally?
yes
What two types of genes are mutated and lead to cancer?
Oncogenes and Tumor suppressor genes