Cancer Cell Biology Exam 1

Front 1

What are the 6 Hallmarks of Cancer?

Back 1

1. Loss of GF-dependence
2. lack of responsiveness to anti-growth signals
3. resistance to apoptosis
4. limitless replicative potential
5. recruitment of blood and lymph (angiogenesis)
6. invasion and metastasis

Front 2

What are the 3 major phases of cancer development?

Back 2

metaplasia --> dysplasia --> anaplasia

Front 3

What are carcinomas derived from?
Give an example.

Back 3

epithelial origin. Ex: lung, colon, breat, and prostate cancers

Front 4

What are sarcomas derived from?
Give an example.

Back 4

mesenchymal and connective tissues.
Ex: bone and muscle cancers

Front 5

What are leukemias/lymphomas derived from?
Give an example.

Back 5

white blood cell tumors

Front 6

What are germinal tumors derived from?
Give an example.

Back 6

germ cell cancers

Front 7

What is a proto-oncogene?
Give examples.

Back 7

= a normal cellular gene that, upon alteration of DNA-damaging agents or viral genomes, can acquire the ability to function as an oncogene.
ex: c-src, Ras G12, c-myc

Front 8

What is an oncogene?
Give examples.

Back 8

= a gene that can transform cells.
ex: v-src, Ras G12V or G12D, v-myc, overexpressed MDM2 and AKT

Front 9

What is a tumor suppressor gene?
Give examples.

Back 9

= a gene whose partial or complete inactivation leads to an increased likelihood of cancer development; this gene is responsible for constraining cell proliferation.
ex: pRb, p53, p19ARF, PTEN

Front 10

What is the structure of c-src? What is its main task?

Back 10

- 533 AAs long, phosphorylated on Y527 inhibiting phosphorylation of Y416; regulated kinase activity
- required for normal growth and development.

Front 11

How can you activate c-src?

Back 11

1) remove phophoryl group on Y527 and add one on Y416
2) SH2 ligand binding (binds phophorylated tyrosines)
3) SH3 ligand binding (binds polyPro stretches)

Front 12

What downstream signaling pathways of Src lead to Motility?

Back 12

activation of substrates at focal adhesion

Front 13

What downstream signaling pathways of Src lead to Proliferation and Survival?

Back 13

1) Activation of docking proteins --> PI3K --> (PDK1) --> AKT --> mTor --| BD and --> translation and metabolism
2) Adaptors (GEFs) --> Ras --> Raf --> MEK --> MAPK --> translation and metabolism
3) Activation of Tyr kinases --> Stat3 --> Myc and Cyclin D1

Front 14

What downstream signaling pathways of Src lead to Cell-cell adhesion?

Back 14

1) Activation of Tyr kinases --> Stat3 --> Myc and Cyclin D1
2) activation of substrates at cell-cell contacts

Front 15

What is the structure and function of v-myc?

Back 15

- 526 AA long, autophosphorylates at Y416 and is thus constituitively active kinase --> dysregulated cell division, survival, and motility
- gives normal cells transforming ability

Front 16

How is oncogenic v-src activated?

Back 16

1) deletion in c-myc --> gain of function mutation
2) many point mutations (especially in SH3 domain)

Front 17

What is the normal function and structure of Ras?

Back 17

- its a GTPase that is active when bound by GTP (encouraged by GEF) and inactive when bound by GDP (due to GAP)
- mediates GF signaling

Front 18

What is the upstream signaling pathway of Ras?

Back 18

GF binds --> RTKS dimerize and autophosphorylate --> GRB2 binds RTKs via SH2 --> SOS recruited to PM and GRB2 binds it via SH3 domains --> SOS (a GEF) activates Ras --> Sos dissociates

Front 19

What is the downstream signaling pathway of Ras?

Back 19

Raf goes to the PM --> Raf hydrolyzed and activated by Ras --> Raf binds and phosphorylates MEK --> MEK phosphorylates and activates MAPK --> MAPK dimerizes and translocates to the nucleus --> phosphorylation of TFs that promote cell growth

Front 20

What are the 4 downstrean effectors of the Ras pathway? What are the major functions of each?

Back 20

1. Raf-MAPK: transcription, cell cycle progression
2. PI3K- Rac: survival, transcription, translation, cytoskeleton
3. RalGDS: cell cycle progression, transcription, vesicle transport
4. PLC-epsilon: Calcium signaling

Front 21

What 3 things contribute to the diversity of this major Ras pathway?

Back 21

1. 4 different EGF receptor subunits
2. 3 Ras forms (K-, H-, N-)
3. 3 MAPK forms (ERK, JNK, JAPK)

Front 22

What is the signaling pathway that connects Ras and p53?

Back 22

Ras, Myc --> E2F --> ARF --| MDM2 --| p53 --> apoptosis or arrest

Front 23

How is the oncogenic form of Ras formed?

Back 23

from a point mutation: --> RasG12V or Ras G12D

Front 24

What are the 3 Major forms of Ras? What cancers are they associated with

Back 24

1. K-Ras: pancreatic, lung, and colon cancers
2. H-Ras: bladder and urinary tract cancers
3. N-Ras: leukemias

Front 25

What are the 5 Ras pathway components implemented in Cancers?

Back 25

Ras, RTKs, Raf, GAPs, Ligand Overexpression

Front 26

How is Ras implicated in cancer?

Back 26

- locked in a perpetually active state
- mutation destroys GTPase activity

Front 27

How are RTKs implicated in cancer?

Back 27

- overexpression of Her2-neu leads to increased signaling (involved in breast cancers)
- N-terminus truncation --> constituitive Y-kinase activity (signals without ligand)

Front 28

How is Raf implicated in cancer?

Back 28

- overexpression associated with lung and liver tumors
- mutations in B-Raf --> melanomas and colon because it's constituitively on

Front 29

How are GAPs implicated in cancer?

Back 29

- the major one involved: neurofibromin, which is deficient in patients with neurofibrosarcomas, leukemias, etc

Front 30

How is ligand overexpression implicated in cancer?

Back 30

- results in constituitive signaling

Front 31

What is the normal function of c-myc?

Back 31

it is a bHLH-LZ TF that binds DNA with MAX

Front 32

How does MAX act?

Back 32

activating: MYC::MAX (SKP2, HAT::TRRAP)
repressing: MNT::MAX and MAD::MAX (HDAC::SIN3)

Front 33

What are the upregulation and downregulation pathways that involve Myc?

Back 33

upregulation: MYC::MAX bind E boxes --> rtanscription (boxes normally inhibited by MAD::MAX and MNT::MAX)
downregulation: MYC::MAX binds and represses MIZ1 (usually transcribes INR, thus encouraging cell cycle progression)

Front 34

What happens to a loss of myc in developing organisms?

Back 34

Smaller organisms

Front 35

In what 3 ways does Myc drive cell cycle progression?

Back 35

1. drives CyclinD-CDK4/6 expression --> phosphorylation of pRb
2. by inhibiting MIZ1, it decreased p15INK4b, p21, and p27 expression
3. increases expression of E2f1-3 proteins in late G1

Front 36

What is the pathway that links p53 and myc?

Back 36

Myc, Ras --> E2F --> ARF --| MDM2 --| p53 --> apoptosis or arrest

Front 37

By what a3 methods does myc become oncogenic?

Back 37

1) gene amplification: (N- and L- myc) N-myc in childhood neuroblastomas
2) viral insertion before promoter: v-myc
3) chromosome translocation: (c-myc) in Burkitt's Lymphoma - B-cell tumor caused by reciprocal translocation between c-myc and IgG locus, resulting in myc before a very strong promoter

Front 38

What does increasing [MYC] do?

Back 38

- increases the number of MYC::MA complexes, thus increasing transcription
- increased upregulation and increased downregulation --> tumorigenesis
(includes transformation/angiogenesis, apoptosis, cell-cycle progression, blocks cell differentiation, genomic instability, reduced dependence on GFs, and increased cell size)

Front 39

What 5 features does Myc affect to lead to tumorigenesis?

Back 39

cell-cycle, growth, deaht/immortality, adhesion matrix, and genomic instability

Front 40

How does Myc affect cell-cycle and lead to tumorigenesis?

Back 40

increases cdc25A, CDK4, and cyclin D2, while decreasing CDKI, p21, and p 27

Front 41

How does Myc affect growth and lead to tumorigenesis?

Back 41

increases eIF4E and decreases H-ferritin = larger cells

Front 42

How does Myc affect death/immortality and lead to tumorigenesis?

Back 42

death: increases p53 and ARF
immortality: increases hTERT

Front 43

How does Myc affect adhesion matrix and lead to tumorigenesis?

Back 43

decreases collagen fibronectin (no dependence)

Front 44

What is the normal function of pRb?

Back 44

It is integral to cell cycle progression.

Front 45

List the normal functioning pathway of pRb in cell cycle progession.

Back 45

pRb represses E2Fs --> GF binds receptors --> cyclin D expression --> cyclinD-CDK4/6 begin phosphorylating pRb --> pRb begins to release E2Fs --> pRb hyperphosphorylated and pushed through RP --> after this point pRb hyperphosphorylation is maintained through M and GFs have no influence anymore --> phosphatases come in at the end of M --> pRb phosphorylated and repressing E2Fs

Front 46

Who are the members of the "pocket" protein family? What are their concentrations throughout the cell cycle?

Back 46

- all members can alter cell cycle progression when overexpressed
- pRb = p105, concentration is constant throughout
- p107 is induced
- p130 decreases

Front 47

What signaling pathway connects pRb to p53?

Back 47

Myc, Ras --> D-CDK4/6 and E-CDK2 -| Rb-E2F --> E2F --> RP --> p19ARF --| mdm2 --| p53 --> p21 (and p16INK4a) --| D-CDK4/6 and E-CDK2

Front 48

What is retinoblasotma? What two forms is it observed in?

Back 48

= causes retinal tumors caused by loss of function mutations in Rb
- if inherited, bilateral tumors appearing autosomal dominant due to LOH
- if acquired via 2 somatic mutations, then unilateral tumors

Front 49

How are cells immortalized by viral oncogenes interacting with pRb?

Back 49

Viral oncogenes bind B-boxes --> induces conformational change --> change induced in "pocket" --> disturbed Rb form
- ex: SV40, HPV E7 protein, adenovirus E1A

Front 50

How does loss of function in pRb affect cell cycle?

Back 50

It accelerates progression, as there are increased free E2F levels

Front 51

What inhibits CyclinD-CDK4/6 molecules?

Back 51

INK4 family of proteins: p16INK4a, p15INK4b, p18INK4c, p19INK4d

Front 52

What molecules inhibit Cyclin-CDK complexes from late G1 --> M?

Back 52

p21Cip1, p27Kip1, p57Kip2

Front 53

What does E2F release activate? What does it repress?

Back 53

activates p19ARF
represses p27 via phosphorylation --> ubiquitylation --> degradation in the proteasome

Front 54

What are the positive factors in cell-cycle progression? What does the overexpression of these lead to?

Back 54

- Cyclin D1-D3, CDK4/6, Cyclin E
- overexpression leads to a shortened G1

Front 55

Which cell-cycle inhibitor is most often silenced in cancers?

Back 55

p16INK4a is often lost/silenced through Methylation in cancer cells

Front 56

What is the ATM pathway? When does it occur? What is it activated by?

Back 56

ATM activated Chk2 (--> p53), p53, and mdm2 via phosphorylation : all serve to stabilize p53 --> p21 expression --| E-CDK2 --> arrest
Activated by IR when DNA damage occurs before S.

Front 57

How is Li-Fraumeni Syndrome acquired?

Back 57

the inactivation of 1 allele of p53 gene leads to inactivation of 15/16 of p53 tetramer complexes in the cell.
This acts a dominant negative mutation, and patients have an increased likelihood of developing a multitude of cancers

Front 58

In addition to p53 loss of function, what other molecular compound needs be inactivated in order to develop cancer? Why is this?

Back 58

pRb, because loss of function of just one would lead merely to cell cycle arrest.

Front 59

How do malignant cells eliminate the p53 pathway?

Back 59

- pt mutation of p53
- deletion of ARF
- overexpression of MDM2
- p53 localized to the cytoplasm

Front 60

How do malignant cells inactivate apoptosis?

Back 60

- inactivate Apaf-1 promoter
- Bax gene mutation
- increase Bcl2 expression
- inactivate caspase 8

Front 61

What is FLIP?

Back 61

in cancer, this is a molecular structure similar to procaspase 8, which lacks its cleave site, but docks with Fas and blocks procaspase 8

Front 62

What is NF-kB?

Back 62

expressed in cancer cells via death receptor singaling; it is a TF that protects from apoptosis and is associated with differentiation

Front 63

How do cytotoxic T cells or NKs contribute to apoptosis?

Back 63

Tc or NK binds --> releases granzyme B --> activates executioner (casp. 3) --> cascade and Bid

Front 64

What are the anit-apoptotic proteins?

Back 64

Blc2, Bcl-X, Bcl-w

Front 65

What are the pro-apoptotic proteins?

Back 65

Bax, Bak, and Bim and Bid

Front 66

What are the two subunits of Telomerase? What are their functions?

Back 66

TERC and TERT. TERC is the RNA template and TERT contains the reverse transcriptase catalytic subunit

Front 67

What is the Hayflick limit?

Back 67

= cells undergo predictable number of doublings before senescence
this can be suppressed by TERT activation

Front 68

What are some qualities of senescent cells?

Back 68

increased p53, p19ARF, and p16INK4a levels
hypophosphorylated pRb
morphological changes, express SA-beta-Gal, bigger and flatter

Front 69

What happens if you inhibit Trf2? How does this relate to cancer?

Back 69

all chromosomes become linked and enter crisis. the cell interprets this as DNA damage. This formation is accomplished by BFB cycles, resulting in amplifications, deletions, and introduction of large amounts of damage --> new mutations