3rd march

Question 1

What are the three main families of proteolytic enzymes?

Answer 1

Matrix metallo proteinases
Serine proteases
Aspartate and cysteine proteases

Question 2

What is the main function of MMPs?

Answer 2

Extracellular proteolysis

Question 3

what is the main function of serine proteases?

Answer 3

Plasminogen activation

Question 4

What is the main function of aspartate and cysteine proteases?

Answer 4

Involved in lysosomal proteolysis

Question 5

What are the two main types of plasminogen activators?

Answer 5

Tissue PAs

Urokinase PAs

Question 6

What is the key function of tissue PAs?

Answer 6

Intracellular proteolysis

Question 7

What is the key function of uPAs?

Answer 7

Pericellular proteolysis

Question 8

What are the three key functions of plasmin?

Answer 8

Matrix degradation
MMP activation
GF activation

Question 9

Outline the three pathways through which plasmin promotes ECM degradation

Answer 9

Plasmin –> gycoprotein degradation –> increase in MMPs access to collaged –> ECM degradation

Plasmin –> pro-MMP cleavage –> MMP activation –> ECM degradation

Plasmin –> TIMP2 cleavage –> MMP inhibition –> ECM degradation

Question 10

What are the key physiological processes that uPA/uPAR are involved in?

Answer 10

Embryogenesis
Angiogenesis
Wound healing

Question 11

What is PAI-1?

Answer 11

A plasminogen activator inhibitor belonging to the SERIN family

Question 12

How does PAI-1 function?

Answer 12

It disrupts uPAR-VN and integrin-VN binding by binding to the UPA present inthe uPA-uPAR integrin complexes on the cell surface –> LRP endocytic clearance of uPA/uPAR

Question 13

Outline the evidence for the involvement on uPA in aggressive tumours

Answer 13

High level of uPA in breast cancer is associated with a higher incidence of relapse

High uPAR levels are linked to a worse prognosis in breast cancer

Stroma expression may correlate more strongly with relapse than with tumour levels

Plasma levels of soluble uPAR are associated with a poor prognosis in ovarian cancer

Rat cancer model - uPAR increased invasiveness, tumour size and metastasis in vitro

uPA OE in human prostate cells –> more widespread skeletal metastasis when injected into the left ventricle of nude mice

Antibody against uPA inhibits lung metastasis in mice injected with tumour cells
Anti-sense inhibition of uPAR expression in glioblastoma and squamous cell carcinoma lines decreased invasiveness in vitro

Question 14

What are the 5 different types of metalloendopeptidases?

Answer 14

Metzincins
Serralysins
Adamalysin-reated
Matrixins (MMPs)
Astacins

Question 15

What are the three main mechanisms of regulation of MMPs?

Answer 15

Transcriptional upregulation
Proteolytic cleavage
Tissue inhibitors of MMPs (TIMPs)

Question 16

How are MMPs activated?

Answer 16

Soluble MMPs are secreted as zymogens which are activated by cleavage of the pro-domain. MMPs interact with one another and plasmin in a complex interaction cascade.

Question 17

What induces MMP gene expression?

Answer 17

GFs
Cytokines
Chemical agents
Stress 
Oncogenic transformation

Question 18

What are TIMPs?

Answer 18

Endogenous regulators of MMP activity

Question 19

What are the targets of MMPs?

Answer 19

ECM proteins - Col IV and Laminin 5
Release of GFs fro TM precursors e.g. HB-EGF
E-Cad inactivation
RTK extracellular domain cleavage e.g. FGFR1 by MMP2
Integrin cleavage e.g. alphav
ECM fragment production e.g. Col XVIII –> endostatin

Question 20

What are the methods of analysis of MMPs in cancer?

Answer 20

Immunohistochemistry

Northern Blottng

RT PCR

Zymography

ELISA

Cell culture

Animal Models