4: Colorectal cancer development - Wnt Signaling - Cancer stem cells

Question 1

What is Canonical (Wnt)?

Answer 1

accumulation Beta- catenin that is transferred to nucleus and regulates the expression of target genes

Question 2

Where in the intestinal epithelium is Wnt found?

Answer 2

the bottom of the crypts and top of the wili

Question 3

what is the consequence of APC mutations?

Answer 3

• Complex for Beta- Catenin destruction is not formed → Wnt target genes transcription
  Uncontrolled proliferation and migration throughout vili and crypts

Question 4

What is the cancer cell theory?

Answer 4

cancer stem cells
- can give rise to new tumors
- resemble the tissue stem cell in expression pattern and behaviour
be aware
- stem cells divide rather slowly while chemo attacks fast dividing cells
- better protect their DNA ex. radiation

Question 5

how to find stem cells in the intestinal epithelium?

Answer 5

• receptor lgr5 (green) marks rare cells at the bottom of the crypts where stem cells are presumed
• Lgr5+ cells manipulated to express Gfp
• GFP cloned behind Lgr5 + promotor