2.4. Water-soluble vitamins
Folic acid (FA, vitamin B9) is a natural vitamin occurring in
grains, fruits and vegetables and plays an important role concerning
DNA biosynthesis, DNA repair and DNA methylation (Fig. 8)
[148]. FA also modulated miRNAs involved in the development of
different cancer types. Rats fed with a folate-deficient diet produced
HCC after one year associated with upregulation of let-7a,
miR-21, miR-23, miR-130, miR-190, and miR-17-92 as well as suppression
of miR-122 in the developed hepatomas [149]. FA consumption
was accompanied by upregulation of miR-122 leading to
efficient blocking of liver tumorigenesis [149,150]. In addition,
increased expression of miR-222 was observed from lymphoblastoid
cells devoid of FA supplement [151]. FA was also applied for
certain “theranostic” purposes involving miRNAs since FA receptors
are often overexpressed on the cell surface of cancer cells. A
nanoprobe consisting of a gold nanoparticle modified with a fluorescein
isothiocyanate (FITC)-labelled molecular beacon (MB tha