Phosphoinositide 3-kinase c(PI3Kc) is a critical mediator of directional cell movement. Here, we sought to characterise the role of PI3Kc in mediating the different steps of polymorphonuclear leukocyte (PMN) trafficking in the lung.In a murine model of lipopolysaccharide (LPS)-induced lung injury, PMN migration into the different lung compartments was determined in PI3Kc gene-deficient (PI3Kc -/-) and wild-type mice.Bone marrow chimeras were created to characterise the role of PI3Kc on haematopoietic versus nonhaematopoietic cells. A small-molecule PI3Kc inhibitor was tested in vitro and in vivo. PMN adhesion to the pulmonary endothelium and transendothelial migration into the lung interstitium was enhanced in PI3Kc -/-mice. However, transepithelial migration into the alveolar space was reduced in these mice. When irradiated PI3Kc -/-mice were reconstituted with bone marrow from wild-type mice, migratory activity into the alveolar space was restored partially. A small-molecule PI3Kc inhibitor reduced chemokine-induced PMN migration in vitro when PMNs or epithelial cells, but not when endothelial cells, were treated. The inhibitor also reduced LPSinduced PMN migration in vivo.We conclude that PI3Kc is required for transepithelial but not for transendothelial migration in LPS-induced lung injury. Inhibition of PI3Kc activity may be effective at curbing excessive PMN infiltration in lung injury.

A simple and cost-effective HPLC method was established for quantification of 5-hydroxyeicosatetraenoic acid (5-HETE) in human lung cancer tissues. 5-HETE from 27 patients' lung cancer tissues were extracted by solid-phase extraction and analyzed on a Waters Symmetry C(18) column (4.6 x 250 mm, 5 microm) with a mobile phase consisting of methanol, 10 mM ammonium acetate, and 1 M acetic acid (70:30:0.1, v:v:v) at a flow rate of 1.0 mL/min. The UV detection wavelength was set at 240 nm. The calibration curve was linear within the concentration range from 10 to 1000 ng/mL (r(2) > 0.999, n = 7), the limit of detection was 1.0 ng/mL and the limit of quantitation was 10.0 ng/mL for a 100 microL injection. The relative error (%) for intra-day accuracy was from 93.14 to 112.50% and the RSD (%) for intra-day precision was from 0.21 to 2.60% over the concentration range 10-1000 ng/mL. By applying this method, amounts of 5-HETE were quantitated in human lung cancer tissues from 27 human subjects. The established HPLC method was validated to be a simple, reliable and cost-effective procedure that can be applied to conduct translational characterization of 5-HETE in human lung cancer tissues.