Midterm 1 Flashcards
benign
-grows slowly
-low mitotic index
-well-defined border
-not invasive
-doesn’t metastasize
-can be removed surgically
malignant
-grows rapidly
-high mitotic index
-not defined/not encapsulated
-invasive
-spreads distantly (metastasis)
solid tumors
-epithelia (carcinoma)
-connective tissue (sarcomas)
-nervous system (neuroectodermal tumors)
diffuse tumors
blood tumors
-leukemia, lymphoma
somatic mutation theory (SMT)
-mutations gives cell a growth advantage
-leads to clonal expansion
-successive mutations giving greater advantages and more clonal expansion
cancer in the context of evolution
- mutation gives cell competitive advantage
- selective pressures from body prevent mutation from growing
- the only cells that survive are the ones that randomly mutate to be resistant
driver mutation
causes/contributes to oncogenesis
passenger mutation
accumulate due to poor genome maintenance in cancer cells, but incidental to cancer phenotype
-outnumber driver mutations
cancer=mutation+opportunity
-not every cell with a mutation becomes cancer
-not every cell with an oncogenic mutation becomes cancer
what are experimental models to study cancer?
-cell culture (yeast, bacteria)
-animals: genetically induce cancer or transplant human cancers into immunocompromised animals
-humans (organoids, genetics)
functional analysis of potentially cancerous mutations
is it necessary?
-remove a part and see if processes are turned off
is it sufficient?
-add one thing and see if process is turned on
necessity tests-how to remove a gene or protein?
-gene knockouts
-interference with RNA (knockdowns)
-interference with protein (function blocking antibody, dominant-interference
sufficiency tests-how to add a gene or protein?
-gene: deliver gene construct that results in gene expression
-RNA: inject X into mRNA
-protein: inject X protein
reverse transcriptase PCR (rtPCR)
-isolate cells, then mRNA
-reverse transcribe mRNA to cDNA
-use primers to amplify specific regions
-measure output thru gel, fluorescence, etc
in situ hybridization
-fix whole tissue
-use a probe that is the DNA sequence reverse complement of gene being tested
-tells spatial where the gene is located
RNAseq
-isolate mRNA
-PCR to cDNA and add adapters sequence
-map result back to the genome
western blot
-separates protein by size
-uses a fluorescent antibody to target specific protein
flow cytometry
cells of interest are labeled with antibodies and sorted using a laser
immunohisochemistry(IHC)/ immunoflurescence
-primary antibody binds to antigen of interest
-2nd antibody is fluoresently labeled
-can see where antigen is located
immunnoprecipitation
isolation of proteins and other biomolecules from cell or tissue lysates for the purpose of subsequent detection by western blotting and other assay techniques.
cyclin dependent kinase (CDK)
add a phosphate group to proteins to activate or inactivate them
-always present in a cell
-default function is inactive
-only active when bound to a specific cyclin
cyclins
activate CDKs
-specific cyclins are made at specific times
Wee1 kinase
inhibitory phosphorylation
cdc25 phosphatase
removal of inhibitory phosphorylation
CAK
activating phosphorylation
spindle assembly checkpoint (SAC)
misalignment of chromosomes prevents CDK from activating APC
-alignment of chromosomes is detected by a conformational change in proteins on the chromosome caused by microtubule attachment and tension (during metaphase)
-prevents cell from going into anaphase until all chromosomes are aligned
oncogene
encodes a protein that can cause cancer
proto-oncogene
“normal” unmutated version of an oncogene
Her2
receptor that regulates cell growth and division
ligand
small protein or molecule
receptor
transmembrane protein that binds to extracellular cue and initiates intracellular signals
effector
generally many molecules acting in cascade can cluster by protein-protein interactions motifs
transcription factor
regulate gene expression
cell signalling
-transmission from outside of cell to nucleus
-fast ON and OFF
-energetically cheap
gene expression
-slow ON and OFF
-stable changes
-energetically costly
receptor tyrosine kinases (RTKs)
-high affinity cell surface receptors for polypeptide growth factors
-causes trans-autophosphorylation
-activate Ras/MAPK pathway
-transient phosphorylation syncs with entry into S phase
EGF (epidermal growth factor)
-small protein that stimulates epithelial cell division
-binds to EGF receptor
steps of RTK firing
- specific ligand binding (EGF binds)
- stable dimerization of RTK by EGF binding
- trans-autophosphorylation
-triggers tyr phosphorylation of downstream effectors
how are mitogens/RTKs linked to the cell cycle
-many growth factors signal through RTKs
-activating the Ras-mediated MAPK pathway to promote proliferation
what are mutations in RTK firing that are oncogenic?
-mutations affecting structure: lack of ligand binding site that results in the constant dimerization and phosphorylation of the tyr kinase domain
-mutations causing overexpression: mutation in regulatory region that results in constitutive expression, results in molecular crowding and unregulated phosphorylation and unregulated cell growth
herceptin that targets Her2
antibody therapy
-blocks cleavage of Her2, prevents signal transduction pathway
-blocks dimerization, prevents signal transduction pathway
-endocytosis: downregulates Her2 by bringing it inside the cell
-activation of antibody-dependent cell-mediated cytotoxicity: immune effector cell binds to herceptin, results in a immune attack and lysis of the tumor cell
oncogene
gene capable of transforming a normal cell into a tumor cell
v-onco
-viral oncogene
-gene carried in a virus, derived from a cellular gene, promotes proliferation in infected cell
c-onco
-cellular oncogene
-gene that promotes cellular proliferation in a controlled manner under normal situations
Rous experiment
- sarcoma in a chicken is removed
- grind up sarcoma with sand and pass thru fine pore filter
-only allowed virus thru - inject filtrate into chicken and observe to see if tumor grows
Results: discovered RSV
focus assay
way to measure oncogenic properties
-an immunostaining technique and a variation of the viral plaque assay
