Due to the poor prognosis of the
human ductal adenocarcinoma of the pancreas (PDAC) it is of
major importance to identify novel target genes with high
functional relevance to provide a better diagnosis or new
therapeutic approaches. In this study, 91 potential candidate
genes identified as differentially expressed in carcinogenic
pancreatic tissues in previous high-throughput analyses were
functionally characterized. To this end, the technology of
“reverse transfection“ was established in our lab to perform
the analyses in a highly parallelized microarray approach.
Overexpression and knockdown experiments were carried out in
transformed and nontransformed cell lines for all candidates
to screen for subcellular localisation of the gene products
and their impact on cellular functions like apoptosis,
proliferation and differentiation. Data evaluation led to the
selection of 10 genes which showed significant and
reproducible effects in the parallelized experiments. One of
them was Cofilin-1 (CFL1), a member of the ADF/Cofilin family
of actin-binding proteins. Parallelized microarray analyses
revealed a previously undocumented growth-regulatory effect
of this gene in pancreatic cancer. Subsequent detailed
characterization demonstrated a strong overexpression of CFL1
in PDAC on mRNA as well as on protein level. RNAi-mediated
knockdown of CFL1 in 4 different cell lines led to a
significant inhibition of cell growth whereas apoptotic
cascades were not affected. Furthermore, a significant
decrease of anchorage-independent growth was observed in soft
agar assays. Flow cytometric analyses indicated an
attenuation of the G1 to S phase transition. Aside from its
growth-regulatory function, migration assays revealed an
additional inhibitory effect of CFL1 on cell motility
identified in “time lapse” and wound healing assays. In
contrast to this, a directional migration analyzed in Boyden
Chamber analyses remained unaffected. Based on these data and
the current state of the literature, the results of this
study present for the first time a direct growth-regulatory
effect of CFL1 in pancreatic cancer.