Cancer and Stem Cells Flashcards
(26 cards)
How does the body function and how does cancer break rules?
Body functions as ecosystem where Cells are usually committed to apoptosis if damaged, also committed to collaboration and cancer hurts this system by hurting rest, growth division, differentiation, and apoptosis
What are the types of cancer?
Carcinomas (epithelial tissues), sarcomas (connective and muscle tissues), leukemias and lymphomas - blood cells
What are the properties of cancer cells?
cells reproduce despite restraint on cell growth and division, cells invade local tissue and can colonize foreign locations
Describe benign vs malignant tumors
benign - non invasive
malignant - invasive
How do tumors progress and convert a healthy cell to a cancer cell?
multiple mutations are required to convert a healthy cell to a cancer cell, mutations can be present due to inheritance, chemical carcinogens, radiation, errors in dna replication, and defects in dna repair
Why is PET used to detect cancer cells?
Cancer cells have increased glucose uptake and metabolism, since tumor cells do more glycolysis making it possible to visualize them with radioactively labeled glucose in PET scan
What is cell senescence and how do cancer cells get around it?
cell division counting mechanism, depends on shortening of telomeres, provides a built in limit to number of times a cell divides
cancer cells get around this by keeping telomeres active, preventing them from shortening over time, checkpoints are disabled, so cell cycle proceeds
Describe cancer cell properties
decreased sensitivity to anti proliferative signals, less likely to undergo apoptosis, defective in cell cycle mechanisms, induce angiogenesis (formation of new blood vessels), use stromal cells for support, stabilize telomere length
How does cell division and apoptosis impact cells
Increased cell division and/or decreased apoptosis can cause a cell to be a tumor
Why do cancer cells accumulate mutations?
• Mutations are accumulated at a higher rate in cancer cells
than in normal cells in part due to inability to repair DNA
damage or undergo proper chromosome segregation.
Describe cancers that arise from a single cell
cells within the tumor share common chromosomal abnormalities (translocations), genetic mutations (point mutations), or epigenetic changes
Describe cancer critical genes that cause an overactivity or underactivity mutation
Myc, Ras - overactivity mutation (gain of function), activating mutation enables oncogene to promote cell transformation
Rb, p53 - underactivity mutation (loss of function), tumor suppressor gene is eliminated through 2 mutation events
How can an oncogene be made?
Gene amplification, deletion or point mutation in coding sequence, regulatory mutation, chromosome rearrangement (produces hyperactive fusion protein)
What is dna from tumor cells tested for
DNA from tumor cells can be tested to see if it causes abnormal cell proliferation. Results in ID of Ras.
What is the difference between hereditary and nonhereditary retinoblastoma
Individuals with inherited Retinoblastoma have a greater chance of developing a tumor
What are the mechanisms of gene inactivation?
Genetic - accidental change in nucleotide sequence, epigenetic - accident causes dna packaging into heterochromatin or methylation of C nucleotides
What are tumor suppressors and protooncogenes?
Tumor Suppressors: Rb, p16
• Proto-oncogene: Cyclin-Cdk
• E2F can inhibit and promote the cell cycle depending on which one is active
What is the role of p53?
P53 - tumor suppressor, components of p53 pathway mutated in almost all cancers
Stable, active p53 leads to cell cycle arrest, apoptosis
What are the stages of tumor progression?
Stages of tumor progression -
- Normal Epithelium
- Low grade intraepithelial Neoplasia - cell proliferation
- High grade intraepithelial neoplasia - more cell proliferation, basal lamina not invaded yet .
Invasive Carcinoma - cancerous tumor
Describe the progression of colorectal cancer
Loss of Apc (not anaphase promoting complex, helps keep Wnt signaling pathway off), activation of K-Ras, loss of smad4 and other tumor suppressors, loss of p53, other unknown alternations
What does metastasis require?
requires disruptions in cell cell and cell-matrix adhesion
What are the difficult and easy steps in metastasis?
escape from parent tissue and colonization of remote site is difficult, travel through circulation is easy
What does the tumor microenvironment look like?
includes cancer cells, includes stroma, Stromal cells evolve to support the cancer cells.
What do tumors induce in order to survive?
Tumor induce angiogenesis, secrete signals that attract endothelial cells for the growth of blood vessels to the tumor. • Tumors require blood vessels to supply nutrients and oxygen to survive
