Vitamin D and colorectal cancer (1.15)

Question 1

In the absence of Wnt, what does APC do to beta-catenin?

Answer 1

Phosphorylates –> ubiquitination –> degradation

Question 2

What is Wnt’s effect on APC?

Answer 2

Inactivates it… beta-catenin is NOT degraded

Question 3

What happens when beta-catenin accumulates?

Answer 3

It translocates to nucleus –> binds to Lef1/TCF –> activates tsx of target genes (Cyclin D1 and myc)

Question 4

Tests were done on mice concerning APC(min/+) and VDR(+/-): what were the results?

Answer 4

APC(min/+)VDR(-/-) had elevated cyclin D1 expression and decreased p21 and p27 expression

Question 5

What is the effect of increased cyclin D1 and decreased p21 and p27?

Answer 5

Tumor(s)

Question 6

How much vitamin D is needed to reduce incidence of colorectal adenoma?

Answer 6

A lot… the highest concentration had better results