To identify novel targets in
pancreatic cancer cells, we used high-throughput RNAi (HT-RNAi) to select genes that, when silenced, would decrease viability of
pancreatic cancer cells. The HT-RNAi screen involved reverse transfecting the
pancreatic cancer cell line BxPC3 with a
siRNA library targeting 572
kinases. From replicate screens, approximately 32
kinases were designated as hits, of which 22
kinase targets were selected for confirmation and validation. One
kinase identified as a hit from this screen was
tyrosine kinase nonreceptor 1 (TNK1), a
kinase previously identified as having
tumor suppressor-like properties in embryonic stem cells. Silencing of TNK1 with
siRNA showed reduced proliferation in a panel of
pancreatic cancer cell lines. Furthermore, we showed that silencing of TNK1 led to increased apoptosis through a
caspase-dependent pathway and that targeting TNK1 with
siRNA can synergize with
gemcitabine treatment. Despite previous reports that TNK1 affects Ras and NF-κB signaling, we did not find similar correlations with these pathways in
pancreatic cancer cells. Our results suggest that TNK1 in
pancreatic cancer cells does not possess the same
tumor suppressor properties seen in embryonic cells but seems to be involved in growth and survival. The application of functional genomics by using HT-RNAi screens has allowed us to identify TNK1 as a growth-associated
kinase in
pancreatic cancer cells.