Detection of cancer progression markers via PCR

Question 1

What is colorectal cancer?

Answer 1

• The third most common cancer in the world
• A major cause of mortality
• 50% pf the patients sufferfrom relapse (recurrence of colorectal cancer)
• The current mecnisms involved in its recurrence remains unknown

Question 2

How can colon cancer be diagnosed?

Answer 2

• Colonoscopy
• Biopsy and analysis, e.g. immunohistochemsitry
• Blood tests, e.g. carcinoembryonic antigen (CEA)
• Scan, e.g. CT, MRI and PET scan
• Molecular testing of tumor

Question 3

What is a biomarker?

Answer 3

A naturally occuing molecule, gene or characteristic by which a particular pathological or physiological process, disease etc can be identified

Question 4

Explain Epithelial-Mesenchymal transition (EMT)

Answer 4

1. Tight junction dissociation and loss of microvilli
2. Adherant junction and desmosome dissociation, loss of apical-basal polarity
3. Increased expression of mesenchymal markers such as alpha smooth muscle actin (αSMA). Cytoskeleton reorganisation and migration occurs
4. Increased expression of ECM proteins and enzymes such as MMPs which causes basement membrane degradation. This allows them to invade adjacent tissue

Question 5

Explain EMT in tumor progression

Answer 5

1. Decreased expression of epithelial markers and overexpression of mesenchymal markers
2. Mesenchymal cells can break down the basement membrane to invade adjacent tissue
3. They can produce their own ECM to further facilitate their migration process
4. Hypoxia condition the the center of the tumour
5. The highly migratory mesenchymal cells can break down blood vessels to further envade the circulation
6. This allows them to invade distant tissues/ organs to create a secondary tumour (metastasis)

Question 6

Where can colon cancer metastise?

Answer 6

Into:

• The lungs
• The bone
• The liver
• The brain
• The lymph nodes

Question 7

What are cancer stem cells?

How can they generate new tumours?

How can they cause/contribute to relapse?

Answer 7

• Cancer cells that posses characteristics associated with normal stem cells, specifically the ability to give rise to all cell types found in a particular cancer sample
• CSCs may generate tumours through the stem cell process of self-renewal and differentiation into multiple cell types
• Such cells are hypothesied to persist in tumours as a distinct population and cause relapse and metastasis by giving rise to new drug resistant tumours