ACVIM lectures Flashcards
What is the warburg effect?
aerobic glycosis
T/F Cancer cells stop using oxidative phosphorylation in favor or glycosis
False- they continue to do same amount of oxidative phos AND additionally use glucose for glycolysis
What is another substance that can be used for energy creation?
glutamine
What effects dose lactate have on the tumor microenvironment?
- immune suppression/escape (impact APC, increase Tregs)
- enhance angiogensis (increased VEGF/IL8)
- enhance tumor cell migration/invasion (ECM/integrins)
What impact does lactate have on patient outcome?
high lactate- worse outcome
TKTL1 activity correlates to what activity of glycolysis?
increased so higher activity worse outcome (eval in mammary tumors once)
18F-FDG-PETCT is sensitive or specific?
sensitive
2-DG (inhibits glycolysis) results in what changes in invasion and metastasis?
reduced - possibly due to reduced cathepsin levels (which degrades ECM)
Cancer stem cells can do what actions?
initiate and maintain tumor growth and produce heterogenous tumor population
What is symmetric cell division with stem cells?
two identical daughter cells
What is asymmetric cell division in stem cells?
stem cell and more differentiated progenitor cell (limited self renewal and lead to terminal differentiation)
What are common stem cell markers via flow?
CD34, CD133, CD44
T/F There are specific markers that differentiate normal from cancer stem cells
false
What therapies are CSC more resistant to?
RT and chemo
CSC have dysregulation in DNA repair via what mechaanisms?
p53, MDM2, gammaH2AX
Inhibition of EGFR in CSC can lead to what response?
increased sensitivity to chemotherapy and radiation
What is dedifferentiation?
loss of lineage committment and stem cell feature increase
what is transdifferentiation?
change from one lineage (differentiated) to another
Exposure of diff cell to OCT4, cMyc, SOX2, KLF4 results in what?
pluripotent stem cell production
Hypoxia and subsequent HIF1 alpha production upregulates ___ and ____ which can promote dedifferentiation
Oct4 and Nanog
ZEB, SNAIL, SLUG, TWIST transcription factors help to induce what process?
EMT
What metabolic processes do CSC utilize?
either! plastic with ox phos and aerobic glycolysis and can switch
what is metformin and how is it used in cancer research/therapy?
antidiabetic drug and blocks mitochondrial functon
PGE2 mediates what inflammatory processes and cancer processes?
EGFR/VEGFR: proliferation, migration, angiogensis, mets
BCL-2NFkB - apoptosis inhibition
IL12 - immune suppression
MMP2/9 - mets/invasion
T/F PGE2 is a negative regulator of hematopoietic stem cell growth and development
False- PGE2 increases it
Rituximab targets what?
CD20
Herceptin targets what?
HER2
Avastin targets
VEGF
what is phenotype drug discovery?
look for change in cell/tumor then find target later
What is target based drug discovery?
ID target and create drug then test on tumor
T/F high throughput screening typically results in a drug
False- then look at hits and look for leads within those to confirm, increase potency/selectivity, reduced tox etc and then lead optimize the drug
what are the 4 types of ab formulations?
- Mouse
- chimeric
- caninized
- fully canine
what are three main methods for creation of monoclonal ab?
Hybridoma (using mouse)
phage display
transgenic mouse
What is time to development of animal health drug and how many early phase drugs make it to market?
6-8 years
1 in 10 drugs
what is fractional cell kill hypothesis?
drug kills constant fraction of cell population (independent # of cells)
overall results of chemo tx depends on what two conditions?
drug dose and number/freq of tx cycles
what two drug classes are impacted by rate of cell growth (don’t work as well in tumors with non cycling cells)?
antimetabolites and antitumor antibiotics
what are benefits of initial tumor debulking in drug sensitiivty?
- smaller # starting cells (fractional cell kill)
- improved O2 delivery
- recruit quiescent cells to cycle
What are most common sites of alkylation for alkylators and end result?
N7 and O6 guanine and result in strand breakage when repair attempted
What DNA substitution occurs with alkylation of N7 guanine?
C to T (due to modified guanine)
what class of alkylators lead to crosslinks?
bifunctional
What are the nitrogen mustards (5)?
cytoxan ifosfamide mechlorethamine chlorambucil melphalan
What nitrogen mustards must be activated by P450?
cyotxan and ifosfamide
how does melphalan enter cells?
charged and hydrophilic so requires active uptake via AA transporter - via leucine transporter)
what are nitrosurea?
CCNU
BCNU
what are methylating agents?
procarb
dacarab
TMZ
what other action does procarbazine have and what is main lesion caused by it?
MAO
O6
what is main lesion for methylating aklyators?
O6
What alkylators cross BBB?
CCNU and TMZ
What is the role of methylguanine methyltransferase?
repair O6 alkylation
MMR overexpression or underexpression leads to resistance to alkylators?
underexpression
T/F ifosfamdie is given in single fractions because its metabolism can become saturated
False - given as multiple doses bc of saturation which reduced efficacy
Is doxorubicin or metabolite doxorubicinol more cardiotoxic?
Doxorubicinol
interaction of topo II and doxorubicin leads to what?
formation of cleavable complex - so unable to ligate the DS breaks created by topo II
what is MOA of actinomycin D?
intercalation DNA (in GC regions) and inhibition of RNA/protein synthesis
What is MOA of bleomycin?
binds to Fe intracellularly (Cu extracellularly) and then binds O2 and then cleaves DNA (up to 4/complex)
up or down regulation of TopoII alpha leads to resistance to dox?
downregulation
T/F Antimetabolites have high rate of secondary cancer
false b/c doesn’t bind to DNA
What MTX form has most activity
MTX polyglutamates (also traps inside cell)
What are the cytidine analogs?
cytarabine and gemcitabine
what are actions of cytarabine?
inhibition DNA polymerase alpha and incorporate into DNA leading to chain elongation
gemcitabine has what actions?
inhibits RNR, incorporates into DNA, inhibits DNA polymerase
gemcitabine metabolites increase or decrease kinase enzyme actions?
increases - so more active drug made
What are actions of 5-FU?
inhibits DNA/RNA synthesis via incorporation and TS inhibition
what enzyme metabolizes 5-FU?
DPD
what is metabolism process of Rabacfosadine?
hydrolysis
deamination (RL step)
phosphorylation to PMEGpp (analog of dGTP)
what is action of Rabacfosadine?
competitive inhibitor DNA polymerase alpha, deta, episolon and incorporated into DNA
Vincas bind to - or + end of microtubules?
+ end = prevent assembly
taxanes bind where on microtubule?
interior surface
what is main excretion of vincaas?
hepatic
T/F alterations in alpha and beta tubulin leads to reduced affinity for vinca binding
false-makes tubulin more stable to microtubules are more stable (can lead to increased sensitivity to taxanes
What is most common binding site of platinums?
N7 purine (adenine or guanine)
Inter or intrastrand adducts are the main form of platinums?
intra, but interstrand is responsible for main cytotoxicity
Regarding “worst drug rule”, which drug is “worst” and when is it used?
“worst” = use drug that has least cell kill against cell resistant to other drug
use first
For drugs with similar potency, which drug should be used?
more specific agent first and broader action longer
AUC of doxorubicin directly correlates with what in dogs?
absolute neutrophil count and outcome
what impacts acute and chronic cardiotoxicity of doxo?
max plasma concentration
what is max tolerated AUC for carbo in cats?
2.75-2.95mg*min/mL
What is calculation of feline carbo clearance?
GFR x 2.60
What are the routes of metastasis?
direct extension
lymphatic
hematogenous
permation
T/F E cadherin alone is a better prognostic factor compared to the ratio of type IV collagenases
false- ratio is better
metastasis is efficient or ineffecient?
inefficient
what can improved survival of tumor cells in circulation (3 things)?
homotypic tumor aggregation
heterotypic aggregation with lymphocytes/platelets
plasticity of cell membrane
what are two possible fates of disseminated tumors cells?
cell death - (immune recognition or incompatible soil)
survive - (dormancy, recirculation, proliferation)