UHRF1-miRNAs modulate Dnmt3a expression in prostate transformed cells

UHRF1 is overexpressed in many tumours and is an epigenetic regulator required for DNA
methylation (DNAm) by recruiting all DNMTs to methylation sites. UHRF1 is also crucial for
histone modifications, epigenetic gene silencing and has an important impact on prostate
cancer pathogenesis and progression. Here we studied whether UHRF1 could exert its role in
the epigenetic of cancer by changes in microRNA (miRNA) levels in prostate transformed cells.
MiRNAs are small non-coding RNAs that negatively control gene expression and play crucial
functions in all cellular processes. Growing evidences indicate their deregulated expression in
human cancer, proposing miRNAs as oncogenes or tumour suppressors. Besides, miRNAs
can induce gene silencing via epigenetic mechanisms e.g. by targeting a specific gene region
for DNAm and histone modifications or by regulating expression of epigenetic enzymes.
MiRNAs expression profile of siRNA-UHRF1 PC3 cells showed both increased and decreased
miRNA levels. Using different target predictive software, Dnmt3a appeared as a target of two
new miRNAs (miRNA-a and miRNA-b) overexpressed in siRNA-UHRF1 PC3 cells. Levels of
miRNA-a and -b were confirmed by RT-QPCR in siRNA-UHRF1 PC3 and in LNCaP cells (with
UHRF1 and Dnmt3a lower levels than PC3) and the binding of the two new miRNAs to the
Dnmt3a3’UTR and its inhibitory effect were validated by reporter luciferase system. We studied
the effect of the overexpression of miRNA-a and -b in PC3 finding a decrease of Dnmt3a mRNA
and protein, and a decrease in PC3 proliferation. We studied the effects of miRNA silencing in
LNCaP finding an increase of Dnmt3a mRNA and protein, and an increase in LNCaP
proliferation. These data show the role of miRNA-a and -b in the modulation of Dnmt3a and
propose their involvement in prostate cancer progression. Next goal is to study their promoters
evaluating the role of UHRF1 in miRNAs transcription.