Bacteria and cancer

Question 1

In what two ways can bacteria cause cancer

Answer 1

• induce genome instability and mutations

- Tumor-promoting inflammation

Question 2

In what way do bacteria cause genome instability

Answer 2

Bacterial toxins can cause mutations in the genome

Question 3

In what way can a chronic inflammation (due to bacteria) promote tumors

Answer 3

Chronic bacterial infection results in chronic inflammation. That inflammation is tumor promoting is a non-classical hallmark

• inflammation induces endogenous ROS production, damaging DNA and causing mutations (e.g. making epithelial cell become fibrosis like cells)
• Constitutive activation of STAT3 –> inhibition of cell death, TF for IL-6
• constitutive activation of NFkB –> promote cell survival

Both NFkB and STAT3 are non-classical oncogenes

Question 4

How do gram neg bacteria (H.pylori) cause cancer

Answer 4

1. Gram neg bacteria trigger the immune system
2. Recruits neutrophils that produce ROS
3. ROS can induce DNA damage in the host
4. H.pylori can inhibit MMR (DNA repair) - can result in genomic instability
5. The immune response can be active but “useless” like up regulating Treg, absent or exhausted antigen specific T cells
6. H.pylori produce toxins that activate NFkB, PI3K, MAPK and other factors that induce proliferation & survival

Question 5

What is the effect of Genotoxins from bacteria

Answer 5

Bacteria can be secrete genotoxins which damage the DNA.

Question 6

What is the difference in high genotoxins and low genotoxins

Answer 6

when a cell gets High amount of genotoxins the DNA is so damaged that the cells dies
When a cells gets low amount of toxins they get an increase in genome instability and tumor progression