10/4

Question 1

Epidemiology

Answer 1

Study of the distribution, determinants, prevention, and control of disease

Question 2

Different Kinds of Cancer Epidemiology

Answer 2

1. Analytic: cancer’s determinants in human pop.

Men have higher risk of cancer than females, may be due to height

2. Molecular epidemiology: examination of biological markers of exposure, disease, and points in between

Exposure: cytokines, SNPs, FAs in blood

Disease: tumor Histology/differentiation, prostate specific antigen test

Points in between: breast tissue inflammation, DNA adducts, miRNA expression, DNA methylation

Question 3

miRNA Biogenesis

Answer 3

1. Transcription
2. mRNA gets processed by DGCR8 and Drosha
3. Export to cytoplasm by Exportin 5
4. Dicer processing: cuts loop and adjacent mRNA, yields dsRNA, then acted on by helicase
5. Strand selection by RISC
6. Translational repression if good complementary mRNA to the ssRNA, cleave mRNA if total

Question 4

Onco and tumor suppressor miRNAs

Answer 4

miR-221 and miR-222 tumor suppressor: loss results in erythroblastic leukemia, inhibits proliferation in erythroblasts, involves KIT

miR-221 and miR-222 onco: overexpression in aggressive CLL, thyroid/hepatocellular carcinoma, promotes cell proliferation and inhibits apoptosis in various solid malignancies, inhibits p27 that regulates cell cycle

Question 5

miRNA act as Hormones

Answer 5

Released in exosomes or microvesicles while associated with RNA binding proteins, extremely stable

miRNA found in saliva, serum/plasma, urine, CSF

Move through blood to distant cells

Unknown receptors take up miRNA in muscle cells, cause apoptosis that leads to cachexia

Question 6

miRNA Nomenclature

Answer 6

Species specific: hsa-, mmu-

miRNA indication: miR for mature, pri- and pre-miRNA for primary and precursors, MIR for genes

Primary is made from transcription, precursor is after DGCR8 processing, mature is after dicer

miRNA number: 181, 146

miRNA variant: a, b, c

miRNA allele: miR-181a1 and miR-181a2 since multiple copies of same allele

miRNA strand: 3p or 5p, 5p is at the stalk before the loop at the 5’ end of the miRNA

Question 7

Telomeres and Telomerase

Answer 7

Telomeres: TTAGGG, bind different proteins at telomeres to prevent degradation and unwanted associations since one end hangs out

Telomerase: stem cells don’t shorten since have telomerase, a reverse transcriptase (TERT) that contains an RNA template (hTR)

Question 8

Stem Cells

Answer 8

Unspecialized cells that lack tissue-specific differentiation and specialized function

Defined for their capacity of self renewal so divide and daughter cells contain same biological properties

Long lasting and normally quiescent but can proliferate to repopulate injured tissue

Cancer stem cells: dysregulation of normal self renewal pathways that involve cellular pathways like Wnt and tumor suppressor genes like p53

Form transit amplifying cells that gain additional mutations and lead to tumor growth/expansion but are incapable of long term maintenance of the tumor

Question 9

Warburg Effect: Clinical Utility

Answer 9

Do PET scan wit 18-fluorodeoxyglucose (FDG) which is a nonmetabolizable compound

FDG concentrated in tumors, brain will also light up since uses a lot of glucose normally, can’t use FDG for brain cancer, also in bladder since piss out

Tumors are also glutamine hogs

Question 10

Cells of the Tumor Microenvironment

Answer 10

1. Fibroblasts: tumor initiation, growth, and invasion
2. Adipocytes: adipokines increase tumor migration/invasion
3. Tumor endothelial cells: leukocyte recruitment and tumor invasion/metastasis
4. Pericytes: stabilize blood vessels, inhibit endothelial cell proliferation, maintain capillary diameter, regulate blood flow, provide endothelial survival signals
5. Tumor associated macrophages: immune regulation, promote tumor cell growth/development
6. Dendritic Cells: induce vascularity and involved in tumor immune-pathogenesis, have pro/anti tumor functions
7. Mast cells: elaborate GFs, VEGF, MMPs, and chemokines

Promotes tumor development by disturbing the normal stromal-epithelial communication, facilitating tumor angiogenesis, releasing GFs, and inducing state of immunosuppression

Question 11

Cancer Associated Fibroblasts

Answer 11

Activated by: GFs (like TGF-beta, FGF2, and PDGF), ECM professes, and chemokines

Activation leads to: cell proliferation, synthesis of ECM components like tenascin-C, various GFs, chemokines, and expression of alpha smooth muscle actin

Facilitate angiogenesis and make fibrosis (desmoplasia)

Increased deposition of collagen I and III, mediate inflammatory response through chemokines like monocytes chemotactic protein 1 (MCP1) and IL-1

Secrete MMPs and VEGF

Question 12

Desmoplasia

Answer 12

Growth of the stromal component of the ECM that is associated with the tumor

Fibrosis that follows tumor, prominent at leading edge of a carcinoma

Question 13

Cancer Associated Adipocytes

Answer 13

Delipidation to lose lipids, decreased expression of adipocytes markers, over expression of pro-inflammatory factors and ECM-related molecules

Adipocyte derived stem cells differentiate to generate adipose derived fibroblasts that express smooth muscle actin

Transition associated with profibrotic state and enhanced tumor cell migration

Help tumors develop chemo/radioresistance

Question 14

Cancer Associated Endothelial Cells

Answer 14

Control leukocyte recruitment, limits effectiveness of host response against tumor

Express MMPs and TIMPs that influence tumor progression

Tend to form dilated, tortuous, and highly permeable vessels

Question 15

Tumor Associated Macrophages

Answer 15

Help cell proliferate, remodel ECM, promote angiogenesis, aid tumor cells in evading immune response

Change over time-
M1 Macrophage: normal macrophage activity that leads to pro-inflammatory response

M2 Macrophage: produce cytokines like TGF-beta and IL-10 that promote tumor evasion of host immune response

Question 16

Tumor Cell Invasion of the ECM

Answer 16

1. Loosening of cell-cell interactions: E-cadherins function is lost
2. Degradation of BM and ECM: tumor cells secrete proteolytic enzymes or have fibroblasts/inflammatory cells in the tumor microenvironment make proteases

Use MMPs, cathepsin D, plasminogen activators

MMP degradation liberates GFs bound to ECM, proteolytic products of collagen have chemotactic and angiogenic effects

3. Attachment to new ECM components: normal cells die if lose interaction between integrins on basal surfaces that bind to lamins/collagens in BM

MMP activity in Bm generates novel receptor binding sites that tumors recognize, promotes invasion

4. Migration and invasion of tumor cells: tumors propel through BM and proteolyzed ECM, different cell receptors converge on tumor actin cytoskeleton

Leaves microtrack behind trailing edge, can move as single cells or collective cells when well differentiated, use cross talk with fibroblasts and lymphocytes

Question 17

Tumor Cell Spread through Blood

Answer 17

1. Intravasation-
   A. Active: Tumor associated macrophages release TNFalpha and chemokines

B. Passive: increased vascular permeability and increased interstitial pressure pushes tumors into the vessel

2. Intravascular Survival: tumor cells aggregate into clumps with platelets and RBCs, protect from immune cells and enhance implantability of the clump to form a metastatic deposit, guide to site of inflammation/injury so easier to invade

Emboli: tumor cells in circulation activate/bind coagulation factors and form blood clots

3. Extravasation: facilitated by factors released from primary tumor (TGF-beta and TNF-alpha), involves Selection cell adhesion and differential expression may account for homing

Question 18

Metastasis Sites

Answer 18

1. Anatomical location
2. Vascular drainage of primary tumor site: first capillary available to intravascular tumor like colon cancer to liver
3. Tropism of tumor for specific tissues: prostate cancer to bone, tumor cell Adhesion molecules prefer endothelial cells in one particular organ, chemokines may play a role, spleen and muscle rarely develop metastases

Question 19

Common Sites of Metastasis

Answer 19

1. Brain: lung, breast, melanoma, renal cell, colorectal
2. Lung: renal cell, colorectal, melanoma, breast, sarcoma
3. Liver: colorectal, pancreatic, estrogen receptor negative breast, lung, stomach

Gastrointestinal tumors access liver through portal venous system

4. Bone: estrogen receptor positive breast, lung, prostate, renal cell, colorectal

Question 20

Epithelial to Mesenchymal Transition (EMT)

Answer 20

Detachment of carcinoma cells from each other/BM is due to the loss of cell adhesion and the start of cell invasion is aided by the carcinoma cell losing the epithelial phenotype and adopting a more mesenchymal phenotype

Tumor cells at the invading interface more likely to undergo EMT than cells deep in the tumor

Once reach distant site reverse changes to go back to epithelial phenotype

E-cadherins and integrins expression decreased during EMT but E-cadherins present in adenomas

SNAIL and TWIST: Metastasis oncogenes that are TFs that support EMT, decrease expression of epithelial markers like E-cadherins and keratin, upregulate expression of mesenchymal markers like vimentin and smooth muscle actin

Question 21

Microenvironment and EMT Signaling

Answer 21

Type 1 collagen binds to integrins

EGF, FGF, and HGF bind to tyrosine kinase receptor

Also TGFbeta and its receptor

E-cadherins Receptor degraded by MMP3, releases beta-catenin to make it available for transcriptional regulation

Question 22

Biomarker Goals

Answer 22

Subclassify patients for individualized treatment

Benefits of treatment greatly outweigh toxicity risk

Reproducible

High sensitivity/specificity

Question 23

Serum Tumor Biomarkers

Answer 23

1. CEA: primarily for colorectal carcinoma
   Also for GI, breast, lung, prostate tumors
   Benign conditions- smoking, PUD, pancreatitis, cirrhosis
2. PSA: only for prostate tumors
   Benign conditions- prostatitis, BPH, trauma, ejaculation
3. CA125: primarily ovarian carcinoma
   Also endometrial, breast, lung, GI, liver, pancreas
   Benign conditions- menstruation, pregnancy, fibroids, ovarian cysts, pelvic inflammation, cirrhosis, and others

Tumor associated glycoprotein, poor screening tool for ovarian cancer and is not a diagnostic tool, approved for screening for recurrent/residual disease

Question 24

Tissue Biomarkers

Answer 24

Used as predictors of therapy efficacy, not disease prognosis

ER/PR: predicts response to hormonal/chemotherapy in breast cancer, get uneven staining since tumor is heterogenous genetically

HER2: predicts Response of blocking HER2 receptor therapy in breast cancer, nuclear oncogene amplification detected via FISH

CD117 (c-KIT): predicts response to targeted therapy with imatinib (a tyrosine kinase inhibitor)

CD20: in tissue sir on cells, predicts response 59 rituximab (monoclonal antibody) in patients with B cell lymphomas

Question 25

Molecular Biomarkers

Answer 25

Chromosome: Philly chromosome (t9;22) predicts chronic myelogenous leukemia, Use receptor tyrosine kinase inhibitor BCr/Abl to limit proliferation Lynch Syndrome: MLH1, MLH2, MSH6, PMS2 mutations increase risk for colon, stomach, and ovary carcinoma Li-Fraumeni Syndrome: mutation in TP53 increases risk for breast carcinoma, acute leukemia, and other cancers HPV: causes multiple types of squamous cell carcinomas

Question 26

Molecular Biomarkers: Receptor Signaling

Answer 26

EGFR mutation so constitutively active has no treatment in lung adenocarcinoma, needs no GF since constantly work Gefitinib: EGFR tyrosine kinase inhibitor, works in colon since no mutation in receptor K-Ras: multiple signaling pathways, treat most downstream mutations like in ERK, antibody doesn't work on mutated receptor

Question 27

Tumor Specific/Associated Antigens

Answer 27

Tumor Specific: present mutant peptides from mutant cell proteins on MHC Class I Receptor, can get novel peptide splicing from proteasome Tumor Associated: deactivation of embryonic genes not normally expressed in the differentiated cell Overexpression of normal self proteins by a tumor cell changes density of self peptide presentation

Question 28

Evasion of the Immune Response by Tumors

Answer 28

1. Normally MIC expression leads to death from NK cells or T cells, tumors cleave MiC from their surface with a protease and the soluble MIC binds to NKG2D on lymphocytes Soluble MIC undergoes receptor mediated endocytosis while tumor cell survives 2. CD8+ cells are good at killing if express tumor antigens in MHC Class I Receptor, tumor cells downregulate MHC Class I receptors but are vulnerable to NK cells 3. APCs are not activated by tumors and remain in immature state, don't express costimulatory molecule B7 to activate CD8+ T cells, results in anergic T cells 4. Release TGFbeta to limit immune response by negatively regulating TH1 cells and Cytotoxic T cells, upregulates Treg cells that secrete TGFbeta and IL-10 to limit lymphocytes

Question 29

Monoclonal Antibodies against Cancer

Answer 29

Vaccination with tumor antigens kinda works, use tumor Specific antigens Rituximab: for CD20 which is a B cell signaling receptor, treats Non-Hodgkin's Lymphoma, conjugated to radionuclide to irradiate malignate B cells, radiation damages DNA and leads to cancer cell death Bevacizumab: for VEGF and treats colorectal and non-small Cell lung cancer Gemtuzumab: for CD33, treats acute myelogenous lymphoma, antibody is conjugated to a toxin, binds to tumor cell and is internalized, toxin cleaves from conjugate and creates dsDNA breaks that lead to apoptosis of cancer cell