Chapter 10

Question 1

BRAC 1/2 loss of function is associated with loss of which cellular function?

Answer 1

Ability to repair DSB

Question 2

What is the main cause of cancer progression?

Answer 2

A series of selected genetic and epigenetic changes

Question 3

What is ECM and why is important in cancer metastasis?

Answer 3

Interaction between the cell and ECM is essential for cell growth and survival, in transformed cells production of ECM is normally impaired and ability to survive despite lack of ECM contact is a feature of malignancy. Disruption of BM and collagen degradation em breakdown of ECM integrity is one of the rate limiting steps in tumour progression and metastasis.

Question 4

How can cancer cells disrupt ECM?

Answer 4

By aberrant expression of cellular proteases such as MMPs, cathepsins and their inhibitors.

Question 5

Why are the metalloproteinase family ADAMs important in cancer development?

Answer 5

They are important for release of growth factors and cytokines on the cell surface, and they are critical for the activation of NOTCH pathway and EFGR.

Question 6

The biomarker prostate specific antigen is used to evaluate disease progression in people, what kind of proteinase is it?

Answer 6

Kallikrein-

Question 7

Which group of proteinases are responsible for direct digestion of the ECM and activation of other proteases such as urokinase (a plasminogen)

Answer 7

Cathepsins

Question 8

What are integrins and why are they important for cellular function?

Answer 8

Transmembrane receptor proteins of the ECM which are involved in the regulation of wound healing, inflammation, homeostasis, bone resorption, apoptosis, cell proliferation, tumour growth and metastasis. They also form a structural bridge between actin and the ECM

Question 9

How does integrins signalling pathways work?

Answer 9

An outside ligand will be bound to the inegrin, which is transmemiranous and bound to intracellular structures. The contact point with actin contains multiple TKs, such s FAK which can activate downstream pathways such as IP3K and ERK

Question 10

What are cadherins?

Answer 10

Intercellular adhesion receptors that play an important role in assembling adherens junctions and desmosomes.

Question 11

What is the consequence of e-cadherin loss?

Answer 11

It has been associated with increased cellular invasiveness and with EMT

Question 12

Which microenvironmental factors can influence the metastatic potential of a tumour?

Answer 12

Hypoxia, hypoglycemia, low pH, increased interstitial pressure

Question 13

Is tumour metastasis an organ specific process?

Answer 13

The development of distant metastasis tend tooccur in specific organs, it is therefore considered likely that organ-specific adhesive interactions between endothelial cells and the tumour cells, or between tumour cells and growth factors in that organ can influence successful metastatic establishment.

Question 14

Which other, non tumour cells specific factor is likely to influence the pattern of metastasis?

Answer 14

Blood flow

Question 15

How can intravasation (shedding of tumour cells into the vasculature?

Answer 15

1. Invasion of the tumour into the vessel
2. Abnormal vasculature of tumour may permit passage of cells into circulation
3. Induced vascular remodelling by VEGF and FGF may facilitate intravasation

Question 16

What is cross-seeding and how is it facilitated?

Answer 16

When circulating tumour cells are allowed back to the primary tumour, due to the abnormal vasculature of tumours. May be enhanced by IL-6 and IL-8

Question 17

How can tumour cells detach from the primary tumour?

Answer 17

Either by decreased expression of adhesion molecules, increased expression of motility factors, disruption of E-cadherin, EMT, increased production of proteases including MMPs to break down the ECM and basement membrane.

Question 18

What are the major steps of metastasis?

Answer 18

intravasation,, survival in the blood stream, extravasation, initiation of new growth

Question 19

How does cancer cells promote survival in the blood stream?

Answer 19

They can travel with platelets to evade immune surveillance- may also promote cell growth as the platelets contain growth factors such as EGF; VEGF, HGF, and TGF-beta

However, the majority of cells in circulation will arrest in first pass capillary beds such as liver and lung

Question 20

What is important factors for tumour cells to successfully extravate in a new organ+

Answer 20

Multiple proteases are needed, including MMPs, they modify the integrity of the endothelia and provide entry ponits

Question 21

How can tumour cells initiate metastatic growth at a new site?

Answer 21

They can modify the target organ and make the environment more favourable for themselves, example is in bone where metastasis disrupt bone homeostasis
- release PRHrP, IL-6, TNF-alpha secreted by the tumour cells stimulate release of RANCL by osteblasts which stimulate development of more osteoclasts which digest the none and create space for metastasis.

Question 22

Which molecular factors and processes are important for the tumour cells to achieve intravasation?

Answer 22

1. Proteolysis is achieved by activating plasmin (with urokinase) and metalloproteinases creating pericellular zones of proteolysis, has been documented to facilitate metastasis, break down of BM membrane. The process in a complex coordination with adhesion molecules such as integrins which are responsible of activation of the MMPs - the result is digestion of ECM at the tumour edge.

Question 23

How does the MMPs and proteinase inhibitors affect cell growth, angiogenesis and inflammation in the tumour microenvironment?

Answer 23

MMPs and proteinase inhibitors such as TIMPs alter the release of potent growth factors, such as VEGF, TGF-beta, IGF-2. This result in altered bioavailability of growth signals to the cancer cells and impact proliferation. They can also increase expression of ligands activation EGFR or mediate NOTCH activation.

Question 24

How can MMPs impact EFGR activation?

Answer 24

The subgroup of MMPs called ADAMS, release EGF ligands such as TGF-alpha- result in over expression in many cancers.

Question 25

In what way can proteinases and proteinase inhibitors promote metastasis and oncogenesis?

Answer 25

1. Destroy and chance the ECM and basement membrane
2. Increase release of important growth factors, influencing cell growth, survival, angiogenesis and inflammation
3. Promote immune surveillance
4. Influence apoptotic signals through the FAS mediated death receptor
5. Promote cell growth through EGF or NOTCH pathway
6. Help generate a tumour-friendly microenvironment through recruitment of stromal cells

Question 26

What are cancer associated fibroblasts?

Answer 26

Bone marrow derive cells or cells transdifferentiate from epithelial or endothelial cells. Activated by TGF-beta.

Question 27

What is the function of tumour associated fibroblasts?

Answer 27

Promote cancer growth by delivering key growth signals (HFG, FGF), and survival signals (IGF)
Provide ECM components for integrins resulting in cellular pathway activation
Overexpress metalloproteinases, chemochines, angiogenic factors = proangiogenic and pro inflammatory microenvironment

Question 28

Tumour associated macrophages are known to exhibit which protumorigenic functions?

Answer 28

Induce inflammation, secrete growth factors and MMPs, promote angiogenesis and suppress cytotoxic effects

Question 29

Which cytokines are commonly proceed by TAMs and what is the effect?

Answer 29

IL-6 - pro-inflammatory cytokine resulting in leaky vessels promoting intravasation and recruit other inflammatory cells. It is an anti-apoptotic cytokine. Causes up regulation of PD-1 - mediate production of immunosuppressive pathways.

TNF-alpha- produced by TAMs to can activate transcription factors in tumour cells and stimulate proliferation and survival

IL-23- enhance Th17 cells and inhibit Treg cells, Th17 have strong inflammatory effect and has been associated tumour progression. IT also increases angiogenesis and up regulates MMP9 production in tumours.

Question 30

What is EMT?

Answer 30

A process where the epithelial cell looses its polarity and becomes mesenchymal-like cell with increased migratory ability, resistance to apoptosis and increased EMC production.

Question 31

Which surface markers are an indication of EMT?

Answer 31

loss of epithelial markers such as e-cadherin, cytokeratin and laminin, while gaining mesenchymal markers such as N-cadherin, vimentin, fibronectin, and alpha smooth muscle actin.

Question 32

Which transcription factors are considered involved in EMT?

Answer 32

SNAIL, Slug, Twist, Lef

Question 33

Which cytokine is considered important for EMT progression?

Answer 33

TGF-beta, HGF

Miro-RNA may also be involved in regulation of EMT

Question 34

Loss of what adhesion molecule has been linked with EMT?

Answer 34

Loss of E-cadherin

Question 35

Why is EMT considered important?

Answer 35

It is considered an important step in tumour metastasis.

Question 36

What is the role of hypoxia in metastasis?

Answer 36

Hypoxia drive transcription of metastasis related genes through specific HIF1/2 transcription factors

• up regulation of SNAIL and TWIST in EMT
• induce proteinase (uPA, MMP) expression
• OPN, glycoprotein expressed by osteblasts, osteoclasts, influence cell adhesion, angiogenesis, prevention of apoptosis
• VEGF-A production via HIF.1 alpha stimulating angiogenesis

Question 37

What is a metastatic niche?

Answer 37

A site which has undergone molecular changes where CTCs can “home”, the changed documented include up regulation of specific integrins and their ECM ligands, inflammatory chemoattractant expression, involvement of MMPs has also been considered likely.

Question 38

How can membrane vesicles potentially create metastatic niches?

Answer 38

They are derived from tumor cells via outward budding and contain proteins such as receptors, antigens, lipids and nucleic acid. They can potentially provide a horizontal transfer of bioactive molecules to stimulate tumour progression, invasion, angiogenesis and metastasis.