Purpose Nuclear factor κB (NFκB) activity may increase survival and protect cancer cells from chemotherapy. Therefore, NFκB activity may be prognostic, and inhibition of NFκB may be useful for pancreatic cancer therapy. To test these hypotheses, we examined NFκB activity and the effects of inhibiting NFκB in several pancreatic cancer cell lines with differing sensitivities to gemcitabine. Experimental Design The gemcitabine sensitivity of pancreatic cancer cell lines BxPC-3, L3.6pl, CFPAC-1, MPanc-96, PANC-1, and MIA PaCa-2 were determined by 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and fluorescence-activated cell sorting assays. NFκB levels were determined by electrophoretic mobility shift assay and reporter assays. The effects of gemcitabine on NFκB activity were determined in vitro and in vivo. NFκB was inhibited by silencing of the p65/relA subunit using small interfering RNA in vitro and by neutral liposomal delivery of small interfering RNA in vivo, and the effects were evaluated on gemcitabine sensitivity. Results The cell lines L3.6pl, BxPC-3, and CFPAC-1 were sensitive, whereas MPanc-96, PANC-1, and MIA PaCa-2 were resistant to gemcitabine. No significant correlation was observed between basal NFκB activity and gemcitabine sensitivity. Gemcitabine treatment did not activate NFκB either in vitro or in vivo. Silencing of p65/relA induced apoptosis and increased gemcitabine killing of all gemcitabine-sensitive pancreatic cancer cells. No significant effects, however, were observed on gemcitabine-resistant pancreatic cancer cell lines either in vitro or in vivo. Conclusions NFκB activity did not correlate with sensitivity to gemcitabine. Silencing of p65/relA was effective alone and in combination with gemcitabine in gemcitabine-sensitive but not gemcitabine-resistant pancreatic cancer cells. Thus, NFκB may be a useful therapeutic target for a subset of pancreatic cancers.

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The Axl receptor tyrosine kinase belongs to the TAM (Tyro3, Axl, Mer) family of proteins and is upregulated in multiple types of cancers, including non-small cell lung cancer. In normal tissues, TAM receptor tyrosine kinases contribute to immune regulation. In cancer, Axl expression is associated with poor outcomes and is controlled through various transcriptional and epigenetic mechanisms. Preclinical studies have shown that Axl is involved in cancer cell migration, growth, survival and resistance to chemotherapy through activation of multiple downstream signaling pathways, such as Ras/MAPK, PI3K and Rac1. Axl is also expressed on endothelial cells and plays a role in angiogenesis. In preclinical models, Axl inhibition decreases cancer growth and impedes lung cancer metastases. Small molecule Axl inhibitors have been developed and are currently being used as monotherapy or in combination with cytotoxic chemotherapy or anti-EGFR therapy in early clinical trials. Here, we review Axl structure, functions, regulation, and preclinical and clinical studies in lung cancer.

Malignant pleural mesothelioma (MPM) is a rare, but aggressive cancer. Surgery and radiation offer limited benefit, and systemic chemotherapy remains the primary treatment modality for the majority of patients. Vascular endothelial growth factor (VEGF) and its receptor have been recognized as important players in the biology of this disease. Bevacizumab is a monoclonal antibody that binds VEGF and blocks its interaction with the VEGF receptor. Recent studies have shown benefit with the addition of bevacizumab to the combination of cisplatin and pemetrexed in MPM. This combination is now included in the National Comprehensive Cancer Network guidelines (with a category 2A recommendation) as a possible first-line treatment for unresectable MPM in appropriately selected patients. This review discusses the rationale behind the use of bevacizumab in MPM, as well as summarizes the pharmacology, efficacy, safety, and toxicity of bevacizumab across multiple trials. The use of small-molecule inhibitors of angiogenesis in the treatment of MPM is also discussed.

<div>Abstract<p><b>Purpose:</b> Nuclear factor κB (NFκB) activity may increase survival and protect cancer cells from chemotherapy. Therefore, NFκB activity may be prognostic, and inhibition of NFκB may be useful for pancreatic cancer therapy. To test these hypotheses, we examined NFκB activity and the effects of inhibiting NFκB in several pancreatic cancer cell lines with differing sensitivities to gemcitabine.</p><p><b>Experimental Design:</b> The gemcitabine sensitivity of pancreatic cancer cell lines BxPC-3, L3.6pl, CFPAC-1, MPanc-96, PANC-1, and MIA PaCa-2 were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and fluorescence-activated cell sorting assays. NFκB levels were determined by electrophoretic mobility shift assay and reporter assays. The effects of gemcitabine on NFκB activity were determined <i>in vitro</i> and <i>in vivo</i>. NFκB was inhibited by silencing of the p65/relA subunit using small interfering RNA <i>in vitro</i> and by neutral liposomal delivery of small interfering RNA <i>in vivo,</i> and the effects were evaluated on gemcitabine sensitivity.</p><p><b>Results:</b> The cell lines L3.6pl, BxPC-3, and CFPAC-1 were sensitive, whereas MPanc-96, PANC-1, and MIA PaCa-2 were resistant to gemcitabine. No significant correlation was observed between basal NFκB activity and gemcitabine sensitivity. Gemcitabine treatment did not activate NFκB either <i>in vitro</i> or <i>in vivo</i>. Silencing of p65/relA induced apoptosis and increased gemcitabine killing of all gemcitabine-sensitive pancreatic cancer cells. No significant effects, however, were observed on gemcitabine-resistant pancreatic cancer cell lines either <i>in vitro</i> or <i>in vivo</i>.</p><p><b>Conclusions:</b> NFκB activity did not correlate with sensitivity to gemcitabine. Silencing of p65/relA was effective alone and in combination with gemcitabine in gemcitabine-sensitive but not gemcitabine-resistant pancreatic cancer cells. Thus, NFκB may be a useful therapeutic target for a subset of pancreatic cancers.</p></div>

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Background: We have previously shown that the EphA2 receptor is overexpressed in pancreatic cancer. Silencing of EphA2 receptor in combination with gemcitabine decreases tumor growth and metastases in a mouse model of gemcitabine resistant pancreatic cancer. However, regulation of EphA2 expression in pancreatic cancer is unknown. The objective of this study was to determine a possible relationship between Ras/MAPK pathway and EphA2. Methods: Pancreatic cancer cell lines, MPanc96 and MiaPaca-2, were used in this study. Ras was silenced with 2 different siRNA constructs; EphA2 protein and RNA expression levels were measured. ERK involvement in EphA2 regulation was analyzed by treating cells with 2 inhibitors for MEK (U0126 and PD 98059) and siRNA specific for either MEK1 or MEK2. Effect of MEK inhibition on EphA2 mRNA stability was examined by blocking mRNA synthesis with actinomycin D and measuring mRNA degradation by Q-PCR. In order to investigate the role of subcellular localization of ERK in regulation of EphA2 expression, we overexpressed cytoplasmic anchor protein PEA-15, which binds to ERK and sequesters it to the cytoplasm. Results: Silencing of mutant K-Ras decreased EphA2 mRNA and protein levels. EphA2 mRNA and protein levels decreased in a time- and dose-dependent manner after treatment with MEK chemical inhibitors. Inhibition of MEK activity did not affect EphA2 mRNA stability. Silencing of MEK2 but not MEK1 decreased EphA2 mRNA levels. Overexpression of PEA-15 depleted nuclear ERK, indicated by the absence of phosphorylated Fra-1. Depletion of the nuclear ERK did not affect EphA2 transcription, suggesting that EphA2 is regulated through the cytoplasmic ERK. Conclusions: These data suggest that EphA2 levels are regulated by the RAS / MEK2 / cytoplasmic ERK pathway via regulation of EphA2 mRNA transcription. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3920.

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