Background: Targeting DNA mismatch repair-deficient/KRAS-mutant Colorectal Cancer Stem Cells
(CRCSCs) with chemical compounds remains challenging. Modulating stemness factors Bmi-1, Sox-2, Oct-4
and Nanog in CRCSCs which are direct downstream targets of carcinogenesis pathways may lead to the
reactivation of caspase-3 and apoptosis in these cells. Omega-3 DHA modulates different signaling pathways
involved in carcinogenesis. However, little is known, whether in vitro concentrations of DHA equal to human
plasma levels are able to modulate pluripotency genes expression, caspase-3 reactivation and apoptosis in DNA
mismatch repair-deficient/KRAS-mutant CRC stem-like cells.
Methods: DNA mismatch repair-deficient/KRAS-mutant CRC stem-like cells (LS174T cells) were treated with
DHA, after which, cell number and proliferation-rate, Bmi-1, Sox-2, Nanog and Oct-4 expression, caspase-3
activation and apoptosis were evaluated with different cellular and molecular techniques.
Results: DHA changed the morphology of cells to apoptotic forms and disrupted cell connections. After 48h
treatment with 50- to 200μM DHA, cell numbers and proliferation-rates were measured to be 86%-35% and
93.6%-45.7% respectively. Treatment with 200 μM DHA dramatically decreased the expression of Bmi-1, Sox-
2, Oct-4 and Nanog by 69%, 70%, 97.5% and 53% respectively. Concurrently, DHA induced caspase-3 activation
by 1.8-4.7-fold increases compared to untreated cells. An increase in the number of apoptotic cells ranging
from 9.3%-38.4% was also observed with increasing DHA concentrations.
Conclusions: DHA decreases the high expression level of pluripotency network genes suggesting Bmi-1, Sox-2,
Oct-4 and Nanog as promising molecular targets of DHA. DHA reactivates caspase-3 and apoptosis in DNA
mismatch repair-deficient/KRAS-mutant CRC stem-like cells, representing the high potential of this safe compound
for therapeutic application in CRC.