Expression and activity of SRC regulate interleukin-8 expression in pancreatic adenocarcinoma cells: implications for angiogenesis.

Interleukin-8 (IL-8) is an angiogenic factor that promotes growth of pancreatic tumors. The purpose of this study was to determine if c-Src, a protein tyrosine kinase frequently overexpressed in pancreatic cancer, regulated IL-8 expression and to elucidate the Src-mediated signaling pathways that contribute to angiogenesis in pancreatic adenocarcinoma cells. In a panel of pancreatic cancer cell lines, expression of total and activated Src correlated with IL-8 production. Furthermore, ectopic expression of activated Src in PANC-1 cells with low endogenous Src activity significantly increased IL-8 production (P < 0.005). In contrast, pharmacologic inhibition of endogenous c-Src kinase activity or small interfering RNA-mediated "knockdown" of c-Src expression in L3.6pl cells with high Src expression and activity caused significant decreases in IL-8 production (P < 0.005). Inhibition of c-Src activity resulted in decreased phosphorylation of Akt, p38, and extracellular signal-regulated kinase (Erk)-1/2. Significant (P < 0.005) dose-dependent decreases were observed in IL-8 expression by inhibiting Src-dependent signaling molecules Erk-1/2 and p38 but not phosphatidylinositol 3-kinase. To assess the relevance of Src inhibition to angiogenesis, in vivo gelfoam assays were done. Robust infiltration of vessels was observed in gelfoam saturated with conditioned medium from pancreatic carcinoma cells. This angiogenesis was nearly abrogated in gelfoams saturated with conditioned medium from cells treated with the Src family kinase inhibitor, PP2 (P < 0.001). Thus, c-Src regulates critical "downstream" signaling pathways that contribute to expression of IL-8 in human pancreatic tumor cells, suggesting c-Src may be a target for therapeutic intervention in pancreatic adenocarcinoma.

Regulatory role of c-Met in insulin-like growth factor-I receptor-mediated migration and invasion of human pancreatic carcinoma cells.

Pancreatic carcinoma cells overexpress the insulin-like growth factor-I (IGF-I) receptor (IGF-IR) and the hepatocyte growth factor (HGF) receptor, c-Met, which are both known to mediate tumor cell migration and invasion. We hypothesized that IGF-IR and c-Met cooperate to induce migration and invasion of human pancreatic carcinoma cells and that IGF-I-mediated migration and invasion depend on c-Met. Migration and invasion assays were done with the human pancreatic cancer cell line L3.6pl treated with PBS, IGF-I, HGF, or IGF-I plus HGF. To determine if c-Met is necessary for IGF-IR-mediated migration and invasion, c-Met was down-regulated in L3.6pl cells via adenoviral infection with a c-Met ribozyme before IGF-I treatment. IGF-I and HGF increased cell migration and invasion. Furthermore, IGF-I plus HGF had a greater than additive effect on cell migration and invasion compared with either growth factor alone. Down-regulation of c-Met nearly completely inhibited IGF-I-mediated migration and invasion. Our findings suggest that IGF-IR and c-Met cooperate to induce migration and invasion of human pancreatic carcinoma cells. Furthermore, c-Met is required for both HGF- and IGF-I-mediated migration and invasion. Elucidation of the signaling pathways that contribute to tumor progression and metastasis should provide a foundation for the development of targeted therapies for pancreatic carcinoma.

AP23846, a novel and highly potent Src family kinase inhibitor, reduces vascular endothelial growth factor and interleukin-8 expression in human solid tumor cell lines and abrogates downstream angiogenic processes.

c-Src is frequently activated in human malignancies, including colon, breast, and pancreatic carcinomas. Several recent studies have shown that activation of Src family kinases leads to tumor progression and metastasis by increasing cellular migration and invasion, promoting cell growth and survival, and deregulating expression of proangiogenic molecules. Therefore, selective inhibitors of Src are being developed for cancer therapy. In this study, we characterize the biological effects of the novel ATP-based Src family kinase inhibitor, AP23846, in tumor cells with high Src activity. As a lead compound, AP23846 is a potent c-Src kinase inhibitor (IC50 approximately 0.5 nmol/L in vitro, approximately 10-fold more potent than PP2, the most widely used commercially available Src family kinase inhibitor). At concentrations of 1 micromol/L, AP23846 led to complete Src inhibition for 48 hours in cells. No cytotoxicity was observed under these conditions, although proliferation rates were slower. Therefore, this was an excellent inhibitor to examine Src-regulated signaling pathways in tumor cells. AP23846 reduced cellular migration, vascular endothelial growth factor, and interleukin-8 in a dose-dependent fashion in pancreatic adenocarcinoma cells grown in vitro. Correspondingly, cell culture supernatants from L3.6pl pancreatic adenocarcinoma cells pretreated with AP23846 failed to promote migration of hepatic endothelial cells in vitro and failed to support angiogenesis into gel foams implanted s.c. in mice in vivo. These results suggest that Src inhibitors affect biological properties of tumor progression and may be useful as cancer therapeutic agents in more advanced disease.

How Should Surgical Residents Be Educated About Patient Safety: A Pilot Randomized Controlled Trial.

INTRODUCTION: The Accreditation Council for Graduate Medical Education mandates patient safety education without specific curricular guidelines. We hypothesized that a dedicated, adjunctive resident safety workshop (SW) led by surgical faculty compared with an online curriculum (OC) for hospital personnel alone would improve residents' patient safety perceptions and behaviors. MATERIALS AND METHODS: A pilot randomized controlled trial was performed from 2014 to 2015 within a university-based general surgery residency. Control and intervention groups, stratified by postgraduate year, participated in a hospital-based OC; the intervention group participated in an additional SW. Primary outcomes were perceptions of safety culture, teamwork, and speaking up as per the validated safety attitudes questionnaire (SAQ) at 6 and 12 months postintervention. Secondary outcomes included behavioral scores from blinded surgical faculty using the Oxford NonTechnical Skills scale. RESULTS: A total of 51 residents were enrolled (control = 25, intervention = 26). SAQ response rates were 100%, 100%, and 76% at baseline, 6 months, and 12 months, respectively. SAQ scores were similar at baseline between groups and did not change significantly at 6 or 12 months, independent of postgraduate year (PGY) level. Overall NonTechnical Skills scores were similar between groups, but senior residents (≥PGY 4) in the OC + SW group scored significantly higher in teamwork, decision-making, and situation awareness (all p < 0.05). CONCLUSION: An adjunctive, dedicated resident SW compared with a hospital-based OC alone did not significantly improve overall perceptions of patient safety. However, senior residents participating in the SW demonstrated improved patient safety perceptions and had significantly better intraoperative safety behaviors than senior residents in the OC group. Future curricular enhancements should include PGY-level specific education, iterative reviews, and increased faculty involvement. A larger randomized trial may be warranted.

Synergistic activity of the SRC family kinase inhibitor dasatinib and oxaliplatin in colon carcinoma cells is mediated by oxidative stress.

Chemotherapeutic regimens for the treatment of colorectal cancer generally include oxaliplatin, although inherent and acquired resistance is common. One potential mediator of oxaliplatin sensitivity is the nonreceptor protein tyrosine kinase, Src, the activity of which correlates with disease stage and patient survival. Therefore, we investigated the effects of Src inhibition using the tyrosine kinase inhibitor dasatinib on oxaliplatin sensitivity. We show that oxaliplatin acutely activates Src and that combination treatment with dasatinib is synergistic in a cell-line dependent manner, with the level of Src activation correlating with extent of synergy in a panel of six cell lines. Intracellular reactive oxygen species (ROS) are generated after oxaliplatin treatment, and ROS potently activates Src. Pretreatment with antioxidants inhibits oxaliplatin-induced Src activation. In oxaliplatin-resistant cell lines, Src activity is constitutively increased. In a mouse model of colorectal liver metastases, treatment with oxaliplatin also results in chronic Src activation. The combination of dasatinib and oxaliplatin results in significantly smaller tumors compared with single-agent treatment, corresponding with reduced proliferation and angiogenesis. Therefore, we conclude that oxaliplatin activates Src through a ROS-dependent mechanism. Src inhibition increases oxaliplatin activity both in vitro and in vivo. These results suggest that Src inhibitors combined with oxaliplatin may have efficacy in metastatic colon cancer and may provide the first indication of a molecular phenotype that might be susceptible to such combinations.

Src activation of Stat3 is an independent requirement from NF-kappaB activation for constitutive IL-8 expression in human pancreatic adenocarcinoma cells.

Human pancreatic tumors often overexpress the angiogenesis-promoting factor Interleukin 8 (IL-8), in part due to overexpression of NF-kappaB, a frequent occurrence in pancreatic adenocarcinoma. In this study, we demonstrate that reducing c-Src kinase activity, through either pharmacologic inhibition or small interfering RNA-targeted reduction of Src expression, significantly decreased IL-8 expression (P < 0.05) without affecting NF-kappaB-mediated transcription, but by decreasing phosphorylation of STAT3. To ascertain whether Src-mediated expression of IL-8 was dependent on STAT3, we used stable clones expressing a dominant-negative isoform of STAT3 that inhibits endogenous STAT3 phosphorylation and subsequent DNA binding and STAT3-mediated gene expression or a constitutively activated isoform of STAT3. IL-8 expression was significantly lower in clones expressing the dominant-negative isoform and significantly increased in clones expressing the activated isoform (P < 0.05 for both). Pharmacologic inhibition of NF-kappaB activity significantly reduced basal IL-8 expression and tumor necrosis factor-induced IL-8 expression (P < 0.05 for both), yet NF-kappaB activity was not dependent on Src. We therefore suggest that Src activation, through phosphorylation of STAT3, and NF-kappaB are all required for expression of IL-8 a critical angiogenic-promoting factor in pancreatic adenocarcinomas.

Inhibition of SRC expression and activity inhibits tumor progression and metastasis of human pancreatic adenocarcinoma cells in an orthotopic nude mouse model.

The nonreceptor protein tyrosine kinase Src is overexpressed in 70% of pancreatic adenocarcinomas. Here, we describe the effect of molecular and pharmacological down-regulation of Src on incidence, growth, and metastasis of pancreatic tumor cells in an orthotopic model. Src expression in L3.6pl human pancreatic tumor cells was reduced by stable expression of a plasmid encoding small interfering RNA (siRNA) to c-src. In stable siRNA clones, Src expression was reduced >80%, with no change in expression of the related kinases c-Yes and c-Lyn, and proliferation rates were similar in all clones. Phosphorylation of Akt and p44/42 Erk mitogen-activated protein kinase and production of VEGF and IL-8 in culture supernatants were also reduced (P < 0.005). On orthotopic implantation of varying cell numbers into nude mice, tumor incidence was unchanged; however, in the siRNA clones, large tumors failed to develop, and incidence of metastasis was significantly reduced, suggesting that c-Src activity is critical to tumor progression. To examine this possibility further, animals bearing established wild-type tumors were treated with the Src/Abl-selective inhibitor BMS-354825 (dasatinib). Tumor size was decreased, and incidence of metastases was significantly reduced in treated mice compared with controls. These results demonstrate that Src activation contributes to pancreatic tumor progression in this model, offering Src as a candidate for targeted therapy.