Mesenchymal epithelial transition factor (MET) is one of the critical cell signaling molecules whose aberrant expression is reported in several human
cancers. The aim of the study is to investigate the antigene and antiproliferative effect of short triplex forming
oligonucleotides, TFO-1 (part of the positive regulatory
element) and TFO-2 (away from the transcription start site) on MET expression. HepG2 cells transfected only with TFO-1 (but not with TFO-2 and non-specific TFO) significantly decreased MET levels, which is accompanied by decrease in antiapoptotic
proteins and increase in
pro-apoptotic proteins. Phosphoproteome-array analysis of 46 intracellular
kinases revealed hypophosphorylation of about 15
kinases including ERK, AKT, Src and
MEK, suggesting the growth inhibitory effect of TFO-1. Further, the efficacy of TFO-1 was tested on
diethylnitrosamine-induced liver
tumors in wistar rats. T2-weighted magnetic resonance imaging showed decrease in liver
tumor volume up to 90%
after treatment with TFO-1. Decreased MET expression and elevated apoptotic activity further indicate that TFO-1 targeted to c-met leads to cell death and
tumor regression in
hepatoma. Formation of stable
DNA triplex between TFO-1 and targeted gene sequence was confirmed by circular dichroic spectroscopy and gel retardation assay. Therefore, it can be concluded that
DNA triplex-based therapeutic approaches hold promise in the treatment of
malignancies associated with MET overexpression.