Bio of Cancer Final
The purpose of this card is simply to demonstrate that HIFa increases VEGF production in a variety of different ways in addition to going to the nucleus
Post-transcription levels as well HIFa IS SUPER IMPORTANT FOR THE ENVIRONMENTAL FACTORS OF ANGIOGENESIS
What is the PD-L1 ligand? On what kind of cells is it located and what function does this serve?
Programmed death 1 checkpoint protein (PD-1) PD-L1 ligands on the tumor cells Interacts with PD-1 receptors on T cells and this will decrease the function of the T cells
What is a prophylactic and therapeautic vaccine
Prophylactic: One that will prevent you from getting a certain disease Therapeutic: helps you deal with it once you actually get the disease
A good therapeutic technique would be to increase Ephrin B4 levels
True Increased Ephrin B4 levels may decrease the effects of VEGF on abnormal vessel growth
True or False: Pericyte protection of endothelial cells can render these endothelial cells resistant to many common therapeutics
True You have to take away these pericytes if you want to have an effective treatment
True or False: Angiogenesis even occurs in blood cancers
True Angiogenesis occurs around the bone marrow
True or False: Continued modification improves CAR-T Cell effectiveness
True!
Why is tumor angiogenesis necessary for cancer cells to survive?
Tumors require adequate supply of oxygen and nutrients. Access to oxygen is the rate limiting step Without a new blood supply, these tumor cells become hypoxic and can only grow to about 1-2 mm.
Why do hypoxic tumor cells produce VEGF?
Under normal oxygen conditions - HIFa becomes hydroxylated - HIFa then gets degraded by VHL - The whole time in normal oxygen conditions, HIFa stays in cytoplasm and gets degraded Under low oxygen conditions - HIFa doesn't get hydroxylated - HIFa goes into the nucleus and causes increased VEGF production THIS IS A NATURAL PROCESS THAT WE USE IN LOW OXYGEN CONDITIONS THAT CANCER TAKES ADVANTAGE OF
Some metastasis stats
Up to 70% of patients with invasive cancer have metastases at diagnosis. Metastasis leads to 95% of cancer-related deaths Millions of tumor cells are shed daily into the circulation. Less than 0.01% of circulating tumor cells form metastatic lesion
Just a quick overall look at the metastatic cascade before we dive in
Up to now in this class we have covered as far as B- proliferation & angiogenesis
Name the most potent angiogenic growth factor
VEGF Promotes vascular permeability and leakage Increases vascular cell proliferation Increase cell survival Promotes motility
There is a plethora of various members of the VEGF family. Which member of the VEGF family will we focus on and which isoform of VEGF will we focus on Which VEGF receptors will we focus on?
VEGFA165 VEGF receptor 1 & 2 - These are protein kinases
What are the outcomes of VEGF binding to VEGFR1 and VEGFR2?
VEGFR1 = inhibitory activity - Has inside out function VEGFR2 = stimulatory activity - This is the main activating pathway - Triggers activation of all the VEGF pathways like RAS/MAPK (proliferation), increase nitric oxide and permeability, P13K/AT (survival), cytoskeletal changes (actin) & (migration)
What is Angiostatin?
this is a fragment of plasminogen cut by MMPs that will bind to integrin and cause inhibition
Mention some potential future CAR-T cell therapies
- Addition of NK signal receptors - Binding of cancer cells still with stress ligands - Results in T-cell activation - Combining CAR-T cells with checkpoint blockers (CTLA-4;PD-1) - Targeting tumor angiogenic vasculature with antibodies against VEGF
What are the two classes of macrophages?
- Class M1: Tumor suppressive functions. inc release of cytotoxic substances like ROS and stimulates immune response (release of immunostimulatory cytokines) - Class M2: Recruited and transformed in tumor microenvironment & Releases factors that promote the hallmarks of cancer - Also called Pro-tumor TAM (tumor-associated macrophages) common in advanced tumor
How does T-VEC kill cancer cells?
- Direct killing: virus replicates and lyses cancer cells - Systemic killing: Lysed cancer cell releases specific tumor antigens and virus produces molecules (GM-CSF) that cause a strong immune response against tumor cells throughout the body Double whammy!!
What is the ephrin ligand? What is the ephrin receptor and where is it found? What is the outcome of ephrin receptor binding?
- Ephrin B2 is the ephrin ligand located on arterial vessels. This is a GO signal - Ephrin B4 is is the receptor located on venous vessels. This is a STOP signal Ephrin B2 causes the arterioles to keep growing and growing until they reach the ephrin B4 receptor on the venous vessels at which point the arterial vessels stop growing and a capillary is formed. B4 serves as an inhibitory signal here that controls vessel formation.
What kind of cancer is caused by the following viruses: - Epstein-Barr virus - Hepatitis B virus - Human papillomavirus - Helicobacter pylori
- Epstein-Barr virus = Burkitt's lymphoma - Hepatitis B virus = Liver cancer - Human papillomavirus = HPV cervical cancer - Helicobacter pylori = stomach cancer
What is PDGF and what does it do?
- PDGF is a growth factor produced and released by the endothelial cells but it doesn't necessarily cause the endothelial cells to proliferate, it indirectly causes the stabilization of endothelial cells via pericyte recruitment - PDGF will bind to the PDGF receptor on the pericytes - This recruits the pericytes to the endothelial cells to stabilize them This makes sense because as you are synthesizing more endothelial cells, you require more pericytes to attach and help survival.
What are some of the ways that angiogenesis can be used as a therapeutic measure?
- Repair damage from heart attack - Minimize neural damage after stroke - Improve bone healing - Improve circulation in diabetics
What are the three classes of lymphocytes?
- T cells - B cells - NK (Natural Killer) cells
Describe the journey of the cells of the primary tumor to reach the secondary tumor. Include the following terms: Stroma, basement membrane, epithelial cell, endothelial cell, secondary site
- The primary tumor typically sits atop a layer of epithelial cells. These epithelial cells are cells lining the outside of some sort of tissue. - The primary tumor busts through this epithelial tissue and busts through the basement membrane - The tumor cells are now engulfed in the stroma - The stroma panics, goes WHAT THE F*CK IS GOING ON WHAT THE F*CK HOLY SHIT IS THAT A TUMOR OH MY GOD WHAT THE F*CK - This reactive stroma now allows for the tumor cells to undergo EMT (defined in the following card) - These mesenchymal cancer cells can degrade the matrix and bust through into the circulatory system - These mesenchymal cancer cells then exit at some other location and enter the stroma of the new location - Burrows through the stroma, epithelial cell and basement membrane of the new location - The cancer cell then undergoes MET turning back into an epithelial cell so it can chill & proliferate at the new location
Give me a general overview of therapeautic tumor vaccines
- Tumor antigens (along with antigen-presenting cells) are introduced into the patient - The patient's own immune system becomes primed to attack the cancer cells
When we say that we're "genetically modifying the T cells" what are we actually doing?
- We are inserting DNA that will make the T cells code for proteins that can recognize other antigens present on cancer cells, the T cell no longer needs the MHC class 1 presenting antigens to identify the cancer cell. THIS IS THE MAIN BIG DEAL THAT MAKES THIS WORK - We are adding more signaling "activating" domains onto the T cells - We are adding more "co-stimulatory molecules" (possibly ones such as CD28 ligands) These two are counteracting the tumor's initial response to try to hide from T cells Some researchers are even adding "survival factors"
What are the ways that cancer cells can regulate the expression of stress ligands to make less NK cells come to attack?
- cancer cells inhibit production of stress ligands or - secrete these ligands (act as decoy) that limit attack by NK cells
Summarizing cards 82-85, what are the four drugs/methods that we use to inhibit VEGF activity? Note that #4 was not previously covered in any of the above cards
1. Aflibercept- this is a soluble VEGF receptor, it "traps" the VEGF and so this VEGF molecule is no longer capable of inducing angiogenesis 2. Bevacizumab (Avastin)- This was actually the first approved anti-angiogenic drug and is the major drug administered -Avastin is a monoclonal antibody against VEGF. This antibody interacts with VEGF in such a way that it will not allow VEGF to activate the VEGF receptor 3. Ramucritumab- This is another monoclonal antibody, however this drug is an antibody against VEGFR2 blocking VEGF binding 4. Intracellular tyrosine kinase inhibitors- the advantage of this is that these inhibitors can target many members of the tyrosine kinase receptors family that bind a variety of different growth factors
What are the 5 ways in which TSP binding to the endothelial cells will inhibit angiogenesis?
1. Binds to CD36 that will initiate cell death within the endothelial cells therefore the survival of the endothelial cells to then proliferate will be inhibited. Lead to apoptosis 2. TSP cause the endothelial cells to release FAS-L that will bind to the FAS-L receptor ON THE ENDOTHELIAL CELL ITSELF effectively forcing these endothelial cells to pull a Jeffrey Epstein. Lead to apoptosis 3. TSP binds to CD 47 which will inhibit the activation of the VEGF receptor 2 and also goes through a caspace death cycle through creating reactive oxygen species ROS. 4. TSP does the opposite of MMP (these would usually release the VEGF from being sequestered in the matrix). TSP here binds to the VEGF so now you will sequester VEGF. 5. TSP binds to MMPs and inhibits their function in degrading matrix so the matrix will be left intact now.
If you look back on card #84, you may recall that Avastin is a monoclonal antibody against VEGF. This antibody interacts with VEGF in such a way that it will not allow VEGF to activate the VEGF receptor which will inhibit the growth of blood vessels to the tumor cell. What are the 5 ways in which cancer has grown resistant to Avastin?
1. If you block VEGF, the cancer essentially says "hey screw you I have a bunch of these other growth factors that I will upregulate" such as EGF & FGF. The tumor cells use alternate angiogenic growth factors 2. Remember that the cancer can begin to control other cells in its environment and have these other cells do its bidding. The cancer cells will recruit cells from the bone marrow by releasing Pro-angiogenic factors (VEGF,FGF,PDGF,FGF), also IL-6, granulocyte colony-stimulating factor (GCSF), SCF (stem cell factor),SDF-1 (stromal cell-derived factor-1). This will recruit bone marrow cells to come in. - Specifically, the bone marrow cells introduce endothelial progenitor cells (EPC) that trigger vasculogenesis. - From the bone marrow, the tumor cells can also steal myeloid-derived suppressor cells (MDSC) - these are a mixture of TAM and neutrophils (another cell type of the innate immune system) that suppress immune function, promote tumor growth and angiogenesis - Essentially the tumor cells say "oh so you're telling the blood vessels to avoid me? Screw you I'm gonna make my own blood vessels and recruit a bunch of immune cells that will help me proliferate" 3. The tumor cells will double down on its reliance upon bone marrow by now activating stromal cells. Stromal cells are cells that provide the structural and physiological support for hematopoietic (bone marrow) cells. - This leads to increased Pericyte activity on endothelial cells via PDGF secretion increasing EC cell survival - Stromal cells also now induce CAFs (cancer associated fibroblasts) to have high activity secreting pro-angiogenic factors - Also increase the production of SDF-1 that will now recruit EVEN MORE bone marrow derived cells - Also increasing MMP production which could induce metastasis 4. Alternative Vascularization- The now hypoxic cancer cells don't have access to oxygen due to cutting off the blood vessels going to the tumor so the tumor "moves" closer to the existing vessels. This is termed Vessel Co-option. - The cancer cells themselves form vessel-like structures through which blood can flow. They begin to express markers of endothelial cells in essence differentiating into endothelial cells. This is termed vascular mimicry. - Cancer cells are saying "Oh you're cutting off my access to blood vessels? Alacazam bitch I turned myself into a blood vessel screw you" 5. If you cut off blood supply to tumor cells, now you are making these tumor cells hypoxic. Remember from card #55 that hypoxia is one of the triggers of tumor angiogenesis so what happens is that this hypoxia increases expression of HIF1-a and promotes EMT (epithelial-mesenchymal transition) - This increase in HIF1a triggers an increase in Treg (these are immunosuppressive) - Increase cancer stem cells - Increase MDSC (refer back to #2 above) that are a mixture of TAM and neutrophils.
What are the two ways that the NK cells can be activated?
1. Lose MHC class 1 2. Increase stress ligands present on cell surface
Give a broad overview of CAR T-cell therapy. Why is this mode of therapy effective?
1. Patient's T-cells harvested (Leukapharesis) 2. T-Cells activated and then genetically modified with virus to express CAR construct 3. CAR-T cells expanded and reinjected back into patient This is effective because cancer cells counter treatment through not expressing the MHC protein needed for NK cells to kill the tumor cells and cancer cells also counter by not expressing stimulatory proteins necessary for the T cells to kill the tumor cells. Now with CAR T cell therapy we can genetically modify a subset of the patient's T cells to not require either the MHC protein or the stimulatory protein to attack the cancer cell. BUT the CAR-T cell needs to be genetically modified so that it will identify an antigen that the cancer has not down-regulated yet. (If this last part doesn't make sense, look at point #2 on card #22
What are the different ways that tumors can avoid immune destruction
1. Tumor can down-regulate the expression of the antigens necessary for the T cells to bind to the Cancer cells. Remember that T cells must use antigens on the surface of MHC 1 to bind to cancer cells 2. Cancer cells will decrease the number of the antigens that are recognized by the T cells until the only antigens they have left are the ones that are not seen by the T cells. The immunogenic antigens are eliminated only the sneaky ones are left. 3. Tumor cells will decrease the display of MHC 1 molecules so that the T cells won't be able to recognize them 4. Tumor cells can decrease presentation of antigens by expressing lower amounts of proteins (e.g. B2-microglobulin;TAP1) necessary for efficient intracellular trafficking and display of MHC class I molecule/antigen complex 5. Decrease expression of stress ligands MICA A/B that will decrease the natural killer cell attack - Cancer cells can either inhibit the production of stress ligands or secrete these ligands as a decoy that will limit the attack by NK cells 6. Tumor cells first decrease ability to die by apoptosis by increase IAPs (inhibitors of apoptosis) and decrease receptor-mediated (FAS-FASL) apoptosis. After this, tumor cells then release soluble FasL containing vesicles (Fas ligands) that binds/activates FAS receptors on lymphocytes (T cells) and will kill them. 7. Tumor cells can also release TGF-B that will trigger apoptosis in lymphocytes expressing TGF-B receptor. TGF-B can also activate Treg that will decrease all immune cell functions.
What are integrins?
A family of proteins that are involved in cell matrix interactions. The integrins are ligands that will bind to different components of the matrix (in this case the matrix is endothelial cells lining the blood vessels). Some components of the matrix that integrins can bind to are laminin, collagen, and fibronectin These integrins can cause intracellular signaling regarding cell proliferation, survival, migration and increase EGFRs, FGFRs, VEGFRs if they're the AvB5 integrins discussed a few cards down Integrins can have pro-angiogenic signaling or anti-angiogenic signaling
What is T-VEC?
A modified Herpes Simplex Virus which selectively infects and kills cancer cells only normal cells have the mechanism to eliminate the virus; cancer cells do not
What is a T lymphocyte?
A type of white blood cell that is incapable of directly binding antigens. Instead, these guys bind to MHC molecule on the surface of antigen presenting cells and destroy the antigen presenting cell directly. The MHC class 1 receptor will have the antigen displayed on it These use MHC 1 receptors to bind & destroy APCs as well as tumor cells. In either case however, antigens are required.
What kind of receptor is the VEGF receptor?
A tyrosine kinase receptor
What is an oncolytic virus?
A virus that can infect cells, replicate and lyse tumor cells Advantages: it can spread to other nearby tumor cells
What is one reason that delivering chemotherapeutics to cancer patients can not be effective? How may we go about increasing the effectiveness of the chemotherapeutics?
Abnormal angiogenic vasculature often results in poor delivery of chemotherapeutics You can give anti-angiogenic drugs that will clear some of the convoluted vasculature and then afterwards administer chemotherapy. This has been proven to be effective.' He keeps saying "pruning" instead of "clearing angiogenic vasculature" so if he says "pruning" on the test this is what he means
There were two unnamed drugs that he briefly touched upon: - One drug responsible for targeting and inhibiting the growth of endothelial cells (via a VEGF inhibitor) - One drug responsible for targeting and inhibiting the binding of pericytes to the endothelial cells (via a PDGF inhibitor) What were the results of administering the endothelial drug alone, the pericyte drug alone, and administering both together?
Administering the VEGF inhibitor alone that inhibits the growth of endothelial cells: - Led to the prevention of the tumor Administering the PDGF inhibitor alone that inhibits the attachment of pericytes - Led to the regression of the tumor Administering both in unison: - Led to the SIGNIFICANT regression of tumor vasculature. The combination treatment was most effective
Aflibercept is an anti-angiogenic drug, specifically this drug inhibits the function of VEGF, what is its mechanism of action?
Aflibercept is a soluble VEGF receptor, it "traps" the VEGF and so this VEGF molecule is no longer capable of inducing angiogenesis
How does the activity of Angiopoietin 1 & 2 assimilate to control new blood vessel growth?
Angiopoietin 1 & 2 are both secreted by the support Pericyte cells Angiopoietin 1 binds tyrosine kinase receptor (Tie2) on endothelial cells of blood vessel to promote pericyte attachment, remember pericyte attachment increases endothelial cell survival If you want new blood vessels to form (like you do when undergoing angiogenesis), you must detach the pericytes, proliferate the endothelial cells, and then reattach the pericytes to support/stabilize the blood vessels Angiopoietin 2 also binds tyrosine kinase receptor (Tie2) on endothelial cells of blood vessels BUT here it promotes pericyte detachment which is then followed by endothelial cell proliferation. - This is conducive to angiogenesis.
What percentage of cancer deaths are from infectious agents in the US and globally?
Around 9% US cancer deaths from infectious agents 16-20% Cancers (Globally) associated with infectious agents
You will hear the term CAF, TAF, and TAM many times, what are these?
CAF = Carcinoma Associated Fibroblasts TAF = Tumor Associated Fibroblasts Fibroblasts are most common type of cell found in connective tissue and cancer cells can control the action of these cells TAM = Tumor associated macrophages Macrophage = Specialized cells involved in the detection, phagocytosis and destruction of bacteria and other harmful organisms These can promote further cancer progression
What are CD28 receptors and B7 ligands. What role do they play in T cells killing APCs?
CD28 receptors are receptors located on T cells. B7 ligands are molecules attached to APCs For the T-Cell to be completely active, this requires the B7 ligands on the APC to bind to CD28 receptors expressed by T-cells. The CD28 - B7 action is costimulatory
What are cytotoxic T cells and Helper T cells?
CD8+ T lymphocytes that hunt down and destroy antigen presenting cells that have been tagged with a class 1 MHC molecule, the antigen is on the MHC molecule. This kills the APC and the antigen associated with the APC CD4+ Helper T cells kill cells that have been tagged with a class 2 MHC molecule tag - Help activity of T cells, antibody response, and innate response. They increase the response of the entire immune system. - HIV targets helper T cells
What are CTLA-4 receptors and how do they interact with B7 ligands on APCs? What's the purpose of this interaction?
CTLA-4 receptors are located on T cells and they are responsible for binding to B7 ligands Unlike CD28 receptors, these CTLA-4 receptors serve as a negative feedback mechanism to decrease the activity of T cells This is an inhibitory control that balances out the CD28
What is YERVOY?
Called a checkpoint inhibitor An antibody that will inhibit the activity of CTLA-4 receptor action (a negative feedback mechanism) on the T-Cell Remember, CTLA-4 receptors serve as a negative feedback mechanism to decrease the activity of T cells Through inhibiting the activity of the CTLA-4 receptors, you are thus having the T cell be constitutively active and working to kick cancer butt.
What's the relationship between survival rate and the levels of tumor infiltrating lymphocytes (TIL)
Cancer immuno surveillance Patients with higher levels of tumor-infiltrating lymphocytes (TIL) have better 5-year survival rate
Angiogenesis isn't some totally new thing that cancer came up with, angiogenesis occurs normally in the body in these ways:
Embryonic development Female reproductive system Wound healing Growth These are all very tightly regulated in a spatial and temporal manner
True or False: Angiogenic vasculature has altered levels of EphrinB2 and not the inhibitory ephrinB4
FALSE Altered levels of both ephrinB4 and ephrinB2
What are the six overall steps of angiogenesis in the context of a tumor cell? Note that the image here is representative only of the sixth step since this step is quite detailed.
First keep in mind that this process of angiogenesis outlined here is not only limited to cancer cells. Normal healthy angiogenesis can occur (for reasons outlined in cards 49 & 50), however in cancer this angiogenesis gets out of control. 1. You need an angiogenic switch. This can proceed via any of the three methods described in card 55. 2. Cancer cells produce VEGF (thoroughly discussed in card #56) 3. Cancer cells direct CAF and TAM to also secrete VEGF. Proteases will also now come in to dissolve the matrix 4. VEGF binds to VEGF receptors on endothelial cells that line the walls of the blood vessels 5. Endothelial cells will now undergo proliferation and a portion of the matrix surrounding the blood vessel will degrade. The endothelial cell will be transformed from a stationary cell to a migratory cell moving towards the tumor cells. 6. The endothelial cells of the blood vessel will fuse to form the angiogenic vessels this is actually quite complex. - The VEGF gradient activates some endothelial cells to gain migratory function (Tip cells) - Other endothelial cells proliferate and form column - Tube formation is induced - Pericytes are recruited
What is the definition of angiogenesis?
Formation of new capillaries at the site of the tumor from pre-existing vasculature
Just a heads up
He keeps calling the new receptor a chimeric t cell receptor
What are the integrins that we will be focusing on that are involved in Angiogenesis? Are these integrins overexpressed or underexpressed? What are the effects of these integrins binding to the matrix of endothelial cells?
Integrins are named AvB3 and AvB5 The overexpression of these integrins will increase VEGF signaling and increase MMP functions, both of which will enhance angiogenesis Remember there are a lot more integrins than these two and some of them can have inhibitory effects that will inhibit VEGF signaling and decrease MMP function. One example of such an inhibitory integrin is illustrated in the integrins that the statins bind to causing a decrease in angiogenic factors.
What are the hallmarks of angiogenic blood vessels?
Intracellular spaces overlapping cells Abnormal cellular processes "Hole" revealing underlying basement membrane Disorganized network with no clear distinctions Pericytes not attached well You're essentially just slapping together blood vessels as fast as possible
How does the PD-L1 ligand on the tumor cells decrease the function of T cells? Give me the mechanism
It will decrease the survival pathway of the T cells by inactivating PI3K kinase ("survival") pathway (AKT) Binding of PD-L1 ligand onto the PD-1 receptor activates SHP-2 phosphatase which activates tumor suppressor PTEN which then inactivates PI3K kinase ("survival") pathway within the T cells resulting in decreased T-cell functions
What is Keytruda?
It's an antibody drug that will block the PD-1 PDL-1 action. Remember that PD-L1 ligands on the tumor cells Interacts with PD-1 receptors on T cells and this will decrease the function of the T cells Thus Keytruda will increase T cell function
When you get HIV, you are most susceptible to which cancer?
Kaposi's sarcoma associated herpesvirus (KSHV) most common
Give me a quick rundown of the two checkpoint inhibitors that we've covered thus far
Keytruda: Programmed death checkpoint inhibitor. This will be detrimental to the PD-1 PDL-1 action. If PD action is blocked then the tumor cells are no longer inhibiting the action of T cells. Yervoy: You're inhibiting CTLA action between T cells and Antigen presenting cells. CTLA action is inhibitory so if you inhibit this action you are now increasing the activity of the T-cells
What are some things that characterize an epithelial-mesenchymal transition (EMT)?
Loss of E-cadherin Loss of cytokeratin Gain of N-cadherin Gain of MMPs Gain of Vimentin Change of cytoskeleton to gain motility, invasiveness, and fibroblast-like shape
How do MHC Class 1 molecules and stress induced molecules influence the activity of NK cells?
MHC Class I molecules tell the NK cells DO NOT KILL ME stress induced molecules signal for the NK cells to kill
What are some examples of an antigen presenting cell?
Macrophages Dendritic cells Memory B cells
What are MMPs? Are tumor cells the only cells making MMPs? If not what other cells are making these MMPs?
Matrix metalloprotease. They help degrade collagen and other endothelial cell membrane (ECM) proteins In other words this degrades the matrix Not only made by tumor cells but also synthesized by CAF, TAM, and Angiogenic activated endothelial cells.
What is the general idea of adoptive cell therapy?
Patients own immune cells (tumor-infiltrating lymphocytes) are removed, selected for their cancer-fighting ability, amplified, and injected back into the patient (with addition of immuno-stimulatory cytokines). Disadvantage: very expensive
Define monocytes and macrophages. Explain how they're related to one another.
Monocytes and macrophages are both cells that are responsible for ingesting and destroying invaders. Monocytes differentiate into Macrophages They're recruited into tumors as they are used for inflammatory response
Do cancer cells have MHC class 1 molecules on the cancer cell surface?
No Cancer cells often down-regulate MHC class I molecules ("loss of self antigen") can increase NK cancer cell killing
Can T-VEC be thought of as passive immunology?
No, T-VEC is helping your immune system recognize the cancer. This is NOT introducing exogenous antibodies into your system, it's boosting your own antibodies (after initially directly killing some cancer cells)
How can a combination of PDGF and Angiopoietin 2 cause a cycle of angiogenesis to occur?
PDGF is attracting pericytes to stabilize the new endothelial cells but at the same time you are producing lots of Ang 2 (angiopoietin 2) to detach those pericytes so you can grow the blood vessels. As the endothelial cells multiply, the PDGF causes more pericytes to come to the endothelial cells to stabilize them.
What is an inside out signal?
Part of intracellular pathways being activated when a ligand binds to its receptor will affect the ability of different receptors to bind to their growth factors An example is VEGF binding to VEGF receptor 1 impacting the ability of VEGF binding to VEGF receptor 2.
Define EMT (epithelial-mesenchymal transition)
Series of genetic and epigenetic alterations giving cancer cells enabling properties for most steps of the metastatic cascade; signals from "activated/panicking" stroma (soil) drives changes Essentially, these mesenchymal cells develop the ability to degrade and move through the matrix. This is necessary for metastasis Furthermore, look at the name- "epithelial-mesenchymal transition". Epithelial cells denote thin tissue forming the outer layer of a tissue's surface. These cancer cells go from epithelial cells to mesenchymal cells.
What is a skin-chamber model?
Skin-chamber model to study angiogenesis Tumors implanted under skin Overlaid with glass chamber Visualize tumor and vessel growth Can add inhibitors Treatment of tumor with antagonist to VEGF receptor (bottom) results in decreased angiogenic vasculature surrounding tumor
What is outside in signaling?
Some component bind to cell surface receptor and then you have some kind of signaling going on This is mainly what we've been talking about thus far
What are the triggers for angiogenesis to occur? In other words, name the three "switches" of angiogenesis
The activation of VEGF (an activator) and deactivation of TSP (thrombospondin is an inhibitor of angiogenesis) ONCOGENES can specifically impact angiogenic factors - Activating oncogenes RAS and MYC will downstream activate VEGF and decrease TSP TUMOR SUPPRESSORS can also specifically impact angiogenic factors - Downregulation of P53 will downstream increase VEGF levels and decreased TSP levels. This is because normally, P53 is responsible for decreasing VEGF and increasing TSP ENVIRONMENTAL FACTORS can also specifically impact angiogenic factors. THESE ARE NOT MUTATIONS LIKE THE ABOVE TWO - The cancer cells that have not yet undergone angiogenesis are growing hypoxic with time meaning they don't have enough oxygen. These cells are now going to produce VEGF (mechanism discussed in following card) and direct macrophages as well as fibroblasts to produce VEGF.
What do we mean when we say we are developing a tumor microenvironment?
The cancer cells will literally begin taking over all other cells in a given environment. This environment leads to the development metastasis.
What are the four "tasks" that must be achieved in order for angiogenesis and metastasis to occur?
The goal here is to have the blood vessels grow to the tumor site 1. Cell proliferation of the endothelial cells lining the wall of the blood vessel 2. The matrix/blood vessel wall must be degraded 3. The epithelial cells lining the wall of the blood vessels have to migrate towards the cancer 4. Reestablish the structure of this blood vessel to supply blood to the tumor. 5. Tumor gets into the blood vessels and metastasize at another location in the body
When tumor cells undergo angiogenesis, the new vasculature of the blood vessels are very abnormal. What does a normal blood vessel look like?
There's an endothelial cell layer with tight junctions in the inner-most layer of the blood vessel There's an underlying vascular basement membrane There are closely associated support cells named Pericytes
What are B lymphocytes?
These are a type of white blood cell that have antibodies against specific antigens (viruses, toxic stuff, etc.) You have a few of these for each antigen at birth, once they're stimulated then they differentiate into plasma cells that secrete a ton of antibodies B lymphocytes will indirectly target cells The illustration also demonstrates how memory B cells function. *humoral immune response, primary and secondary immune response*
What is passive immunology?
These are antibodies not made by you against common antigens (which take the form of receptors on the surface of cancer cells)
What are the benefits of using a Tag2 mouse line?
These are bred to develop pancreatic cancer which could give us better insight as to how cancer develops rather than shoving a bunch of cancer cells in some mice
True or False: Immunocompromised patients do show a significant increase in common cancers associated with infectious origins (through viruses)
True Even cancers without infectious agents really screw with you as well if you're immunosuppressed
What are statins? How are they activated? What is their mechanism of action and what do they do?
These are fragments of proteins that are being released upon matrix degradation caused by MMPs. Upon degradation these become active and these are anti-angiogenic. These statins all bind and activate integrins. THESE INTEGRINS ARE NOT INVOLVED IN PRO-ANGIOGENIC PATHWAYS. THESE INTEGRINS THAT THE STATINS ACTIVATE ARE INTEGRINS THAT INHIBIT ENDOTHELIAL CELL PROLIFERATION/GROWTH AND INHIBIT MMP MEDIATED MATRIX DEGRADATION. Summary: Statins are inhibitory
What are Natural Killer (NK) cells? What subtype of cells are these?
These are lymphocytes that are involved in innate immune response. Used for immediate removal of viral particles or foreign/abnormal cells
When developing anti-angiogenic therapeutics, why is it a good idea to target endothelial cells?
These cells are not cancer cells, of course they can be taken over and directed by tumor cells but the endothelial cells themselves represent a genetically stable target that have not sustained a mutation. Additionally, killing an endothelial cell can result in killing hundreds of cancer cells supported by it.
How are natural killer cells mediated? Why don't NK cells kill healthy cells?
They kill in the absence of MHC class 1 molecules and kill cells that express stress-induced molecules Normal, healthy cells express innate MHC class I molecules and do not express stress-induced molecules. This inhibit NK cell-mediated death
What is thrombospondin (TSP)?
This is a large glycoprotein that interacts with multiple matrix components and cellular receptors serving to inhibit all stages of angiogenesis from survival of endothelial cell to EC proliferation and even matrix degradation (through the inhibition of MMPs) You can think of this as essentially the opposite of VEGF
Ramucritumab is another anti-angiogenic drug, specifically this drug inhibits the function of VEGF, what is its mechanism of action?
This is another monoclonal antibody, however this drug is an antibody against VEGFR2 blocking VEGF binding
Bevacizumab (Avastin) is an anti-angiogenic drug, specifically this drug inhibits the function of VEGF, what is its mechanism of action?
This was actually the first approved anti-angiogenic drug and is the major drug administered Avastin is a monoclonal antibody against VEGF. This antibody interacts with VEGF in such a way that it will not allow VEGF to activate the VEGF receptor
In addition to binding VEGFR1 and VEGFR2, VEGF also binds to neuropilin receptors 1 or 2. What do the neuropilin receptors do?
Through intracellular pathways, neuropilin will stimulate the activity of VEGFR2. This is inside out signaling You can think of neuropilin as sort of a coactivator that will increase angiogenic pathway response
What is the function of Treg?
Treg decrease all immune cell functions •Treg cells normally produced to provide tolerance to self-antigens • Decrease autoimmune reactions
True or False: Therapeutics of tumor angiogenesis can actually make the cancer worse
True
I mentioned vasculogenesis in the previous card. Define vasculogenesis and distinguish this from angiogenesis.
Vasculogenesis = new blood vessels forming from progenitor cells that can then be incorporated into existing vessels Angiogenesis = the proliferation of endothelial cells on existing blood vessels
Define MET (mesenchymal-epithelial transition) and how this is necessary for the progression of cancer
We are going from mesenchymal cancer cells (mesenchymal cells were necessary for the cancer cells to bust through the matrix and get into the blood stream) to epithelial cells because this phenotype is required by normalized stromal (soil) environment of target tissue. This transition allows reestablishment of structure needed for secondary growth
One way to prevent angiogenesis can be through blocking the action of pericytes as pericyte action is needed for the stability of new blood vessels. How can we go about blocking Pericytes?
We can administer PDGF receptor inhibitors. Remember PDGF binds to the PDGFR on pericytes causing the pericytes to migrate to & stabilize the endothelial cells this was explored in card #67 If we block the PDGF from binding now the pericytes will no longer provide support to the new endothelial cells and these endothelial cells are now super sensitive to chemotherapy
Okay so now how do we modify our T cells in response to the cancer cells fighting back?! The cancer cell fight back is thoroughly discussed on card #41.
We use CRISPR technology to: - remove genes that encode the normal T-cell receptor (TRAC;TRBC). He calls this the endogenous receptor - Remove the PD-1 receptor; Remember that this receptor is located on the T cell and shuts down the activity of the T cell when bound to the PDL-1 ligand. - Use a lentivirus to add a chimeric T cell receptor, this target a specific antigen that the cancer cell has hopefully not yet down-regulated This is illustrated very well in the image, take a look at it.
When we release MMPs, we will of course degrade the matrix of the endothelial cells (when we say degrade the matrix this essentially means that we will be destroying some of the endothelial cells lining the wall of the blood vessel), but what are the ramifications of this beyond matrix degradation?
When you release MMPs: - You create a migratory path for the epithelial cells of the blood vessel to now form a bridge to the tumor cells - Inside the matrix, you have lots of sequestered VEGF, degrading the matrix will release a ton of this VEGF to upregulate angiogenesis - Activating other matrix components - Some matrix proteins are usually inactive but once you degrade the matrix then these can become active all of a sudden. These matrix proteins can be activators or inhibitors (inhibitor example is statins)
How can cancer cells fight back against CAR-T cells? In other words, how do CAR-T cells become exhausted?
a) Cancer cell decreases expression of antigen (mutation or clonal selection). b) During production of CAR-T cells some cancer cells also become altered with CAR-T construct. Results in cancer cells "masking" ability of CAR-T cells to bind cancer cell. This means that the CAR-T cells become much less effective, they become (exhausted). c) Tumor cells (and other stromal cells in solid tumors) secrete inhibitory molecules and induce expression of Treg d) These can decrease proliferation and survival of CAR-T cells e) Tumor cells increase expression of checkpoint PD-L1. Another total cock-block f) Car-T cell receptors compete with endogenous T-cell receptors to decrease effectiveness. In other words, the Car-T cell has both its regular crappy receptor that doesn't work because cancer doesn't express MHC receptors and it the Car-T cells also have this new high tech receptor that works super well. The crappy receptor cock-blocks the good receptor.
What is endostatin?
fragment of Type 18 collagen- this was the first anti-angiogenesis drug that was developed This binds to integrins and inhibits angiogenesis
What is Provenge?
•FIRST FDA approved therapeutic vaccine •Used for metastatic prostate cancer - Patient's APC cells (monocytes) removed - Outside the body, these monocytes are exposed to the PAP antigen along with an immune reagent GM-CSF. - The monocyte has now been converted into a dendritic cell (these are the major APC for the immune system). You now have an army with heightened immune response • reinjected into patient
A quick run down of some of therapeutic antibodies
•Vectibix (Panitumumab) "human" antibody (made in transgenic mice) against EGF Receptor colorectal cancer •Herceptin: "humanized mAB HER2 Receptors; Breast cancer •Avastin: anti-VEGF (Vascular Endothelial growth factor) decrease angiogenesis •Rituxan mAb targeting CD20 antigen found on many B-cell cancers; non-hodgkins lymphoma (NHL) These are all variations that are mono-clonal antibodies that are specific to one kind of antigen