The inflammatory tumor microenvironment (TME) has many roles in tumor progression and metastasis, including creation of a hypoxic environment, increased angiogenesis and invasion, changes in expression of microRNAs (miRNAs) and an increase in a stem cell phenotype. Each of these has an impact on epithelial mesenchymal transition (EMT), particularly through the downregulation of E-cadherin. Here we review seminal work and recent findings linking the role of inflammation in the TME, EMT and lung cancer initiation, progression and metastasis.Finally, we discuss the potential of targeting aspects of inflammation and EMT in cancer prevention and treatment.

Definition of the molecular pathogenesis of lung cancer allows investigators an enhanced understanding of the natural history of the disease, thus fostering development of new prevention strategies. In addition to regulating epithelial-to-mesenchymal transition (EMT), the transcription factor Snail exerts global effects on gene expression. Our recent studies reveal that Snail is upregulated in non-small cell lung cancer (NSCLC), is associated with poor prognosis, and promotes tumor progression in vivo. Herein, we demonstrate that overexpression of Snail leads to upregulation of Secreted Protein, Acidic and Rich in Cysteine (SPARC) in models of premalignancy and established disease, as well as in lung carcinoma tissues in situ. Snail overexpression leads to increased SPARC-dependent invasion in vitro, indicating that SPARC may play a role in lung cancer progression. Bioinformatic analysis implicates TGF-β, ERK1/2, and miR-29b as potential intermediaries in Snail-mediated upregulation of SPARC. Both the TGF-β1 ligand and TGF-βR2 are upregulated following Snail overexpression. Treatment of human bronchial epithelial cell (HBEC) lines with TGF-β1 and inhibition of TGF-β1 mRNA expression modulated SPARC expression. Inhibition of MEK phosphorylation downregulated SPARC. MiR-29b is downregulated in Snail overexpressing cell lines, while overexpression of miR-29b inhibited SPARC expression. In addition, miR-29b was upregulated following ERK inhibition, suggesting a Snail-dependent pathway by which Snail activation of TGF-β and ERK signaling results in downregulation of miR-29b and subsequent upregulation of SPARC. Our discovery of pathways responsible for Snail-induced SPARC expression contributes to the definition of NSCLC pathogenesis.

FLT3 (FMS-like tyrosine kinase 3) is a member of the class III receptor tyrosine kinase family, which is highly expressed in the blasts of both AML and ALL patients. In addition to FL ligand stimulation, FLT3 can also be activated by two distinct clusters of mutations: internal tandem duplications (FLT3/ITDs) in 20% to 25% patients and point mutations at position D835 in the tyrosine-kinase domain (FLT3/TKD) in 7% to 10% patients. FLT3 tyrosine kinase inhibitors (TKI) are mainly active against FLT3 mutant AML. An antibody drug conjugate (ADC), directed against the extracellular domain of FLT3 may only require FLT3 cell surface expression independent of mutation status. The restricted cellular distribution of FLT3 receptor and a higher expression in AML than in normal bone marrow makes FLT3 a favorable ADC target. Therefore, this ADC based strategy may offer a therapeutic alternative for AML patients independent of FLT3 status. Here, we report the preclinical assessment of a novel FLT3 targeting ADC, AGS62P1. AGS62P1 consists of a human anti-FLT3 monoclonal antibody, site specifically conjugated to a potent cytotoxic payload. FLT3 expression is confirmed in a large panel of AML and ALL tumor cells as well as in AML patient specimens via flow cytometry. The anti-leukemic activity of AGS62P1 was evaluated against AML and ALL tumor cell lines, in vitro and in vivo. AGS62P1 demonstrated strong binding affinity (0.1-0.5 nM) and potent cytotoxic activity in FLT3/ITD and Non-ITD tumor models, in vitro. Cytotoxic IC50 potency for AGS62P1 was 0.5-13 nM in FLT3/ITD and 0.2-12 nM in FLT3 non-ITD models. A fluorescence based assay confirmed that AGS62P1 is rapidly internalized in AML tumor cell lines. AGS62P1 is highly efficacious in FLT3/ITD and non-ITD tumor xenografts, leading to significant tumor growth inhibition or complete tumor regression. In primary AML patient xenograft drug treatment studies, the engraftment and outgrowth of 5/6 samples were significantly reduced when treated with AGS62P1. Taken together our data demonstrate that AGS62P1 exhibits potent antitumor activity against a broad panel of AML tumor models and primary AML samples, regardless of FLT3 status. We believe AGS62P1 may be an effective and alternative therapeutic for AML patients, which can bypass the TKI mediated resistance and deliver target specific effect through a different mode of action. Disclosures Jin: Agensys: Research Funding. Anand:Agensys: Employment. Dick:Agensys: Research Funding.

Statin drugs, such as lovastatin and simvastatin, block cholesterol synthesis by inhibiting the function of HMG-CoA reductase in the cellular cholesterol biosynthesis pathway. In a recent large case-control study, statins reduced the risk of lung cancer suggesting the utility of statins for lung cancer chemoprevention. In our studies, while both lovastatin and simvastatin dose-dependently decreased proliferation in both histologically normal and K-ras mutated human bronchial epithelial cells (HBECs), it also unexpectedly increased expression of PGE2 in mutated HBECs. The statin-mediated upregulation of PGE2 is most pronounced in K-ras mutated HBECs compared to P53 deleted or EGFR mutated HBECs. Treatment with the cholesterol precursor, mevalonic acid, inhibited statin mediated up-regulation of PGE2 indicating that the effect of the statins on PGE2 is sterol-dependent. We found that the suppression of proliferation by statins is also sterol dependent. Statins up-regulate the production of PGE2 by up-regulating mRNA and protein expression of COX-2. The addition of the MEK inhibitor (U0126) revealed the potential involvement of the ERK pathway for statin-mediated upregulation of PGE2 in HBECs. The combination of statins and a low dose of celecoxib (0.1 micro molar), a COX-2 inhibitor, suppressed the increased production of PGE2 by K-ras mutated HBECs. Studies are underway to determine the effect of statin-mediated upregulation of PGE2 on apoptosis resistance and invasion in K-ras mutated HBECs. Our studies suggest that the combination of statins with a low dose of celecoxib overcomes the upregulation of PGE2 induced by statins alone. Thus the combination represents a potentially effective lung cancer chemopreventative regimen worthy of further investigation. Citation Information: Cancer Prev Res 2010;3(12 Suppl):B57.