Purpose: Recent studies have shown that cancer stem cells are resistant
to chemotherapy. The aim of this study was to compare RIF1 gene
expression in head and neck, pancreatic cancer and glioma cell lines and
the cancer stem cells isolated from these cell lines.



Methods: UT-SCC-74 from Turku University and UT-SCC-74B primary tumor
metastasis and neck cancer cell lines, YKG-1 glioma cancer cell line
from RIKEN, pancreatic cancer cell lines and ASPC-1 cells from ATCC were
grown in cell culture. To isolate cancer stem cells, ALDH-1 for
UT-SCC-74 and UT-SCC-74B cell line, CD-133 for YKG-1 cell line and CD-24
for ASPC-1 cell line, were used as markers of cancer stem cells. RNA
isolation was performed for both cancer lines and cancer stem cells.
RNAs were converted to cDNA. RIF1 gene expression was performed by
qRT-PCR analysis. RIF1 gene expression was compared with cancer cell
lines and cancer stem cells isolated from these cell lines. The possible
effect of RIF1 gene was evaluated.



Results: In the pancreatic cells, RIF1 gene expression in the stem
cell-positive cell line was 256 time that seen in the stem cell-negative
cell line.



Conclusion: Considering the importance of RIF1 in NHEJ and of NHEJ in
pancreatic cancer, RIF1 may be one of the genes that plays an important
role in the diagnoses and therapeutic treatment of pancreatic cancer.
The results of head and neck and brain cancers are inconclusive and
further studies are required to elucidate the connection between RIF1
gene and these other types of cancers.