Pathophysiological roles of Pim-3 kinase in pancreatic cancer development and progression

Pim-3 is a member of the provirus integration site for Moloney murine leukemia virus(Pim)family proteins that exhibit serine/threonine kinase activity.Similar to the other Pim kinases(Pim-1 and Pim-2),Pim-3 is involved in many cellular processes,including cell proliferation,survival,and protein synthesis.Although Pim-3is expressed in normal vital organs,it is overexpressed particularly in tumor tissues of endoderm-derived organs,including the liver,pancreas,and colon.Silencing of Pim-3 expression can retard in vitro cell proliferation of hepatocellular,pancreatic,and colon carcinoma cell lines by promoting cell apoptosis.Pim-3 lacks the regulatory domains similarly as Pim-1 and Pim-2 lack,and therefore,Pim-3 can exhibit its kinase activity once it is expressed.Pim-3 expression is regulated at transcriptional and post-transcriptional levels by transcription factors(e.g.,Ets-1)and post-translational modifiers(e.g.,translationally-controlled tumor protein),respectively.Pim-3 could promote growth and angiogenesis of human pancreatic cancer cells in vivo in an orthotopic nude mouse model.Furthermore,a Pim-3 kinase inhibitor inhibited cell proliferation when human pancreatic cancer cells were injected into nude mice,without inducing any major adverse effects.Thus,Pim-3 kinase may serve as a novel molecular target for developing targeting drugs against pancreatic and other types of cancer.