Lecture 4: Cancer Metastasis

stromal cells in tumor

"Supporting" cells that provide structure or support for parenchymal cells in tumor, they are poorly or unable to develop- bad blood flow/vascular/lympathic system

hypoxia and tumors

***tumor cells may use oxygen inefficiently hence hypoxia*** feature of tumors not found in normal tissue -tumor vascularity: primitive - lots of blood flow but slow -tumor volume not uniformly vascularized

how bloodstream inhibits metastasis

-blood is actively hostile environment for cancer cells (forces can tear them apart) -these cells circulate in blood stream where cells of immune system mare in large number -Involves MHCs and CTLs -Some studies suggests that entourage of platelets escort the cancer cells to safe havens

angiogenic switch results in (3)

1 .increased expression of pro-angiogenic factors by tumor and stromal cells - VEGF, bFGF, aFGF 2. decreased expression of anti-angiogenic factors by tumor/stromal cells 3. recruit bone-marrow derived endothelial progenitor cells

steps to cancer: angiogenesis to end

1. Angiogenesis (tumor cells recruite/est. new blood supply) - mutation can cause up/down regulation 2. Invasion/Metastasis - metastasis cell adhesion is lost; sign of very deranged growth in cell 3. Cancer cells have mechanism to avoid replication arrest at cell cycle checkpoints

steps of cancer (damage to beginning of tumor growth

1. DNA damage (radiation, chem, etc) 2. DNA damage multiplies 3. Proto-oncogenes and TSGs affected 4. Multiple Cellular systems affected 5. Immortalized clonogenic cell development and tumor growth begins

steps of cancer: beginning of tumor growth to escaping...

1. Tumor Growth begins with development of immortalized clonogenic cells 2. Deregulated cell proliferation through genes suppression 3. Cells Fail to respond to growth restriction signals 4. Excess Cells fail to undergo apoptosis 5. Escape from senescence (i.e. cell aging does not happen)

steps to the formation of tumor vasculature via angiogenesis

1. angiogenic factors bind to receptors 2. endothelial cell activation 3. endothelial cell proliferation 4. EC migration and remodeling 5. tube formation

3 determining factors of metastasis

1. appropriate growth factors or ECM environment 2. compatible adhesion sites on endothelial lumenal surface 3. selective chemotaxis at which the organ producing some soluble attraction factors to the tumor cells

motility promoting factors (3)

1. hepatocyte growth factor/scatting factor (HGF/SF) 2. Insulin-like growth factor II 3. Autotaxin

4 triggers of angiogenic switch (more new blood vessels)

1. hypoxia - HIF up regulates VEGF, PDGF, NOS 2. Growth factors, cytokines (VEGF, PDGF) 3. Activated/over-expressed receptors (e.g. EGFR, IGF-1R) 4. Oncogenes - ras inhibits thrombospondin (antiangiogenic) and increases VEGF (angiogenic)

unfolded protein response steps

1. hypoxia stabilizes HIF-1, facilitating heterodimerization (two molecules linked) 2. hypoxia triggers the unfolded protein response (UPR) 3. mammalian target of rapamycin (mTOR) kinase is inhibited by hypoxia 4. this influences the phenotype of hypoxic cells by altering metabolism, angiogenesis, autophagy, and ER homeostasis

4 things that add up to cancer

1. infectious diseases/viruses 2. radiation 3. heredity 4. chemical exposure

3 steps for metastasis

1. intravision - invading surrounding tissues and penetrating the walls of lymphatic and blood vessels 2. circulation - cancer cells are transported by circulatory system through the body 3. extravasation - cancer cells leave the bloodstream and establish metastatic tumors

3 components of invasion

1. matrix degrading enzymes 2. cell adhesion 3. cell motility

step 2 of invasion: transport in bloodstream process

1. penetrate lymphatic vessels 2. regional lymph nodes 3. lodge and grow 4. Lymphatic vessels are connected to Bfs 5. Metastasis 6. cancer cells larger than erythrocytes and get trapped in capillaries 7. cancer cells also also attract large amounts platelets **blood stream is not hospitable to cancer cells radioactivity label cancer cells and inject into bloodstream (less than o.1 survival)

4 mechanisms of oncogenes

1. retroviral integration 2. DNA mutation of regulatory sites 3. gene amp 4. chromosomal translocation

2 parts to cell migration

1. small Rho GTPase family 2. motility promoting factors

3 steps to tumor invasion

1. translocation of cells across ECM barrier 2. lysis (breakdown) of matrix protein by specific proteinases 3. cell migration

steps leading to hypoxia

1. tumor cells supplied with oxygen and nutrients via neo-vessel 2. endothelial cells round and detach, initiating blood flow reduction 3. Tubulin-binding agent initiating depolymerization of tubular cytoskeleton in endothelial cell 4. tumor cells furthest from neovasal start undergoing hypoxia 5. collapse of Tubulin cytoskeleton and endothelial cell detachment and death 6. tumor becomes more and more hypoxic 7. Blood vessels lose patency resulting in cell tumor necrosis (hella inflamed

3 different subpopulations of tumor cells with respect to oxygenation (hypoxia)

1. well oxygenated, viable & dividing 2. well oxygenated, viable & non-dividing 3. poorly oxygenated, viable, & non-dividing 4. anoxic and/or necrotic non-viable

VEGF promotes...

Angiogenesis = new blood vessels from pre-existing BV

major effect of p53

Apoptosis

angiogenesis inhibitors (3)

Bevacizumab: can bind/block VEGF which is a mitogen that stimulates Soranfenib: inhibits VEGFR, PDGF, RAF Sunitinib: PDGFR and VEGFR reduces tumor vascularization and triggers cancer cell apoptosis and thus results in tumor shrinkage

lines around cells

E-cadherin (importnat for cell-tocell adhesion) without the tumor cells can become more invasive

serine proteases (function, location

Function: ECM degradation like gelatin, fibronectin and laminin; activation of numerous preforms of MMPs by pro peptide cleavage Kinds: plasmin, plasminogen activators, cathepsin G. plasmin is synthesized in its inactive preform, plasminogen, which can be converted to plasmin by plasminogen activator

Describe function of TSG. what happens when TSG lose function?

Function: genes providing control of oncogenes recessive genes that function loss of function: loss of both copies is generally required for allow tumor growth lost thru somatic homozygosity (mutation occurs in gene on one chromosome and complimentary chromosome is lost through mitotic disadvantage)

Cancer cells at cell cycle checkpoints

G1 - S: p53 dependent S phase arrest is mediated by Cyclin A&E G2: M mediated multiple gene products

cellular response to hypoxia are mediated by what?

HIF-1

binding and HIF-1

HIF-1 binds to enhancer of EPO gene and named HIF in 1990

cell adhesion involves 2 things ...

Integrins which are expressed on cells surface for cell-matrix adhesion - need ECM to grow unlike cancer E-cadherin/catenin adhesion complex: cell-cell adhesion

erythropoietin and HIF-1 (include dates)

Kidney hormone that promotes red blood cell formation induced by hypoxia (HIF-1) in late 80s

lamellipodia and flipodia

Lamellipodia: cancer invasion, lamelliopedium formation and cell motility are stimulated growth factors Filopodia: protrude from the edges of lameliopodia; helps cells to explore its external experiment to establish focal adhesion points

2 theories of organ selectivity

Mechanistic Theory: determined by the pattern of blood flow Seed and Soil Theory: the provision of a fertile environment in which compatible tumor cells could grow ***explains why cancer cells are attracted to more organs (liver & bones) vs. others

necrotic

Relating to or descriptive of death of a portion of tissue

upstream

Sequences before the transcription start site (given negative numbers).

SDF-1

Stromal Cell Derived Factor 1 expressed when induced by ischemia (lack of blood supply) has chemotaxic effects - it is a chemokine (protein) that plays a major role in cell trafficking and homing of CD34(+) stem cells.

2 types of hypoxia: transient v. permanent

Transient: intermittent(stop-start-stop-start) in nature; can be quite severe....norma tissue, realizes there's less blood so produces less blood cells Permanent: unrelieved hypoxia; severe to pt of causing cell death (tumors)

HIF1 and HIF2 protein is controlled by what?

VHL during hypoxia

microns

a micron is one-millionth of a meter or one-thousandth of a millimeter used to measure viruses

produced during extravasation . this induces endothelial cells to retract... making gaps in capillary walls ... facilitating extraversion

angiopoietin-like protein 5 angptl4

anoxic

anoxic = without oxygen

why is it harder to treat PT through cancer BV

because the blow flow is trash and so the treatment only passes through certain BV

occlusion

blockage

anticancer agents

cause ER stress and activate UPR...thus may be able to show selective toxicity to hypoxic cells

permanent hypoxia: causes, function?

cause/context: when tumor growth outstrips vascular supply function: the hypoxic cells are physically displaced from vessels, oxygen diffusion distance varies with metabolism (>100 microns = profound) tumor pressure on surrounding tissues may further impede blood supply

intermittent hypoxia: cause, mediator, function

cause: vascular spasms via lack or neurological control of vessels mediator: vasopressors secreted by tumors function: increases resistance to radiation and other drugs

adhesion and E-cadherin

cell-to-cell adhesion proteins normally keep cells in place reduced adhesion can be traced to loss of E-cadherin Block E-adherin in non-invasive cancer cell results in them becoming invasive Restore E-cadherin to invasive cancer and this inhibits invasiveness

invasion

change adhesive forces btwn cells activate motility (self-movement) production of protease change adhesive forces between cells

clonogenic

clone forming cell - single cell is able to multiply 1 -> 2 ->4 ->8

Ischemia: definition and function

definition: Lack of blood supply function: induces stroll cell derived factor 1 (SDF-1) expression

severe hypoxic exposure results in..

endoplasmic reticulum (ER) stress and leads to rapid activation of unfolded protein response (UPR)

metalloproteinase

enzymes that break down cartilage

integrin

heterodimeric transmembrane receptors consists of alpha and beta subunits function: provide interactions btwn cells and macromolecules in ECM can affect transcription of MMP genes

HIF-1 =

hypoxia inducing factor 1

HIF-1 staining

hypoxia, blood vessels, necrosis

with HGF/SF what happens

induces scatting and invasiveness

thrombospodin

inhibited by RAS anti-angiogenic

cancer spreads via ___________ & _______________

invasion and metastasis

invasion v. metastasis

invasion: direct migration and penetration of cancer cells into neighboring tissues metastasis: ability of cells to enter bloodstream (or other fluids) and travel to alternate sites to form new tumors( more aggressive tumors than main tumor)

reason for large number of inflammatory cells present in tumor

large number of inflammatory cells present because of dying non-viable cells

tumor attach through microthrombi

localized exposure of basement membrane provides attachment points for potential micro thrombi attachment micro helps with tumor cell formation to travel to BV

chromosomal translocation

mechanism of oncogene abnormal production (mutation) results in part of one chromosome being removed and attached to another recombo may promote oncogene expression

Gene amplification

mechanism of oncogene improper DNA replication leads to multiple copies of gene, promoting up-regulating of oncogene

DNA mutation of regulatory sites

mechanism of oncogene mutation reduces regulatory activity by altering protein transcription

retroviral integration

mechanism of oncogene process: retroviral genome integrates with DNA near oncogene and promotes activation activation promoter reverse transcription, integration

MT1-MMP

metalloprotease; expression promotes tumor growth and angiogenesis through an up-regulation of VEFR expression.

Step 3: extravasation

metastatic= must spread more aggressively by forming angiogenesis (need dat blood supply) become stronger by overcoming harsh condition tumor progression: property changes in tumor cell population as cells get more aberrant traits/become more aggressive

deeper further away from capillary (hypoxia) means.

more inoxic cells = less sensitive to cancer treatment cells with more oxygen (oxic) more sensitive to the treatment unlike cells lacking oxygen (hypoxic)

oxic =

more sensitive to cancer cells

E-cadherin/catenin adhesion complex (cell attachment )

most important cell-cell adhesion molecules reduced expression of the 2 increases tumor cell invasiveness

chemotaxic

movement of a motile cell(moveable) or organism, or part of one, in a direction corresponding to a gradient of increasing or decreasing concentration of a particular substance.

Angiogenesis cascade (4)

na1. VEGF/other factor expression in normal cells 2. BV growth (macrophage & monocytes) in normal cell 3. Tumor growth after transformation to tumor cells 4. BV lumen (Cavity through which blood flows) in endothelial cell surrounded by pericyte clip to hold it intact

is HIF-1 dependent on EPO ?

no, in 1993 it was found that there was HIF-1 activity in cells not expressing EPO during hypoxia

unfolded protein response

occurs when quality control system is overwhelmed produces more ER and chaperone proteins to accommodate the build up of misfolded proteins

original tumor v. metastasis

original = heterogeneous metastases = highly-selected, strong-survival, more aggressive

profound microns in hypoxia

over 100

PDGFR

platelet-derived growth factor

matrix degrading enzyme

required for controlled degradation of components of ECM

proteases involved in matrix degrading enzyme process (component 1 of tumor invasion

serine-, cysteine-, aspartyl-, metalloproteinase

cancers preferential sites for metastasis

stomach and colon cancers like to go LIVER breast and prostate cancers like to go BONE

senescence

the natural physical decline brought about by aging

anti-angiogenic factors

thrombospodin-1 endostatin angiostatin a-IFN

VHL protein

tumor suppressor Von-Hippel-Lindau disease loss of VHL = proteins related to hypoxia are repressed by the restoring of vHL function of VHL= controls HIF-1alpha and HIF-2alpha protein amount during hypoxia binds to HIF during normoxia (during normal O2 level)

HIF-1 location

upstream of VEGF, SDF-1 and other proteins relating to metabolism

VEGFR

vascular endothelial growth factor

vasculogenesis is different from angiogenesis in that....

vasculogenesis: forming of BV where there are no pre-existing ones; specific to embryo angiogenesis: sprouting from EXISTING BV by migration of local endothelial cells