Samenvatting

Over the last decades, medicinal chemists have been searching for compounds that
could specifically target cancer cells and not healthy cells. The human ether-a-go-gorelated
gene K+ channel (hERG) has recently been proposed as an anticancer target
[1]. Structural activity relationships of this ion channel allowed the identification of
positively charged pyridines that could effectively interact with the hERG channel
[2]. In the present study, a library of positively charged pyridine derivatives was assed
for cytotoxicity in leukemia cell line (K562) and an immortalized fibroblast cell line
(C5RO). Structural modifications of the pyridine moiety, side chain and peripheral
aromatic moieties were evaluated. Most positively charged pyridines were cytotoxic
and only some showed great selectivity toward cancer cells, K562 (leukemia cells)
being particularly sensitive to compounds 8, 10b, 10p, 12a, 12i and 12k (Selectivity
Index >6). The structural requirements to induce selective toxicity are discussed to
shed light on the development of new anticancer drugs.
The ability to achieve site-specific manipulation of the mammalian genome has
widespread implications for basic and applied research. Gene targeting is a process in
which a DNA molecule introduced into a cell replaces the chromosomal segment by
homologous recombination, and thus presents a precise way to manipulate the
genome. Recent results have demonstrated that zinc fingers or other mega-nucleases
can stimulate gene targeting up to 2-fold. However, inducing double stranded breaks
in the genome can lead to chromosome loss, chromosomal rearrangements, apoptosis,
or carcinogenesis. In the present study we demonstrate that chemical modulation is a
valuable alternative of enhancing gene targeting. Our results demonstrated that neutral
pyridines are significantly less toxic then positively charged analogous. We describe
the structural requirements to enhance gene targeting in mouse embryonic stem cells,
allowing the identification of a non toxic-neutral pyridine 13c that is capable of
stimulating gene targeting up to 2,4 fold proving that chemical modulation is a valuable
alternative of stimulating gene targeting.