Colorectal cancer (CRC) is the third most prevalent cancer all
around the world. Chemotherapy plays an essential role in the treatment
of CRC while Oxaliplatin, Irinotecan, and 5 - fluorouracil (5-FU) are
the most commonly used chemotherapeutic drugs. However, chemo-resistance
is a major obstacle to successful therapy. It has been shown that
inhibition of Wnt signaling pathway can sensitize the cells to
chemotherapy. Lymphoid enhancer factor (LEF1) is a member of TCF/LEF
transcription family mediating Wnt nuclear responses. The long isoform
of LEF1 is highly expressed in colorectal cancer cells compared to the
normal intestinal cells, in which expression of the short isoform is
dominant. We found that the downregulation of long isoforms of LEF1
makes CRC cell lines more sensitive to the effect of chemotherapeutic
drugs. This sensitivity is imposed by reduced proliferation, increased
apoptosis, or cell cycle arrest. Our results also demonstrated that
there is a balance in the expression of long, and short isoforms of
LEF1. In summary, we showed the role of LEF1 in chemo-resistance of
colorectal cancer cells to Oxaliplatin, Irinotecan and 5-FU.