Lung cancers, malignant mesotheliomas (MM), and fibrosis are devastating diseases with limited treatment strategies, in part due to poorly-effective drug delivery to affected areas of lung. We hypothesized that acid-prepared mesoporous spheres (APMS) (1-2 microm diameter, 40 A pore size) might be effective vehicles for pulmonary chemotherapeutic drug delivery. To assess this, APMS, chemically modified with different surface molecules (lipid, a linker having a terminal amine group, a thiol group, or tetraethylene glycol [TEG]), were evaluated for uptake and possible cytotoxic effects after in vitro administration to murine alveolar epithelial Type II (C10) and human mesothelioma (MM) cells and after intrapleural or intranasal administration to C57Bl/6 mice. APMS coated with TEG (APMS-TEG) were most efficiently taken up by C10 and MM cells. The mechanism of cell uptake was rapid, actin-dependent, and did not involve clathrin- or caveolae-mediated mechanisms nor fusion of membrane-bound APMS with lysosomes. When injected intrapleurally in mice, APMS-TEG were taken up by both CD45-positive and -negative cells of the diaphragm, lung, and spleen, whereas APMS administered by the intranasal route were predominantly in lung epithelial cells and alveolar macrophages. After intrapleural or intranasal administration, APMS were nonimmunogenic and nontoxic as evaluated by differential cell counts and lactate dehydrogenase levels in bronchoalveolar and pleural lavage fluids. In the treatment of lung and pleural diseases, APMS-TEG may be useful tools to deliver chemotherapeutic drugs or molecular constructs.

The ligand hepatocyte growth factor/scatter factor (HGF) and its receptor tyrosine kinase, c-Met, are highly expressed in most human malignant mesotheliomas (MMs) and may contribute to their increased growth and viability. Based upon our observation that RNA silencing of fos-related antigen 1 (Fra-1) inhibited c-met expression in rat mesotheliomas (1), we hypothesized that Fra-1 was a key player in HGF-induced proliferation in human MMs. In three of seven human MM lines evaluated, HGF increased Fra-1 levels and phosphorylation of both extracellular signal-regulated kinase 5 (ERK5) and AKT that were inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitor, LY290042. HGF-dependent phosphorylation and Fra-1 expression were decreased after knockdown of Fra-1, whereas overexpression of Fra-1 blocked the expression of mitogen/extracellular signal-regulated kinase kinases (MEK)5 at the mRNA and protein levels. Stable MM cell lines using a dnMEK5 showed that basal Fra-1 levels were increased in comparison to empty vector control lines. HGF also caused increased MM cell viability and proliferating cell nuclear antigen (PCNA) expression that were abolished by knockdown of MEK5 or Fra-1. Data suggest that HGF-induced effects in some MM cells are mediated via activation of a novel PI3K/ERK5/Fra-1 feedback pathway that might explain tumor-specific effects of c-Met inhibitors on MM and other tumors.Keywords: hepatocyte growth factor/scatter factor; fos-related antigen 1; phosphatidylinositol 3-kinase; MEK5; mesothelioma Malignant mesothelioma (MM) is an insidious tumor associated historically with occupational exposure to asbestos (2, 3). The average survival of patients with MM is less than 1 year after initial diagnosis, and no successful treatment options exist. Although the mechanisms of development of MM are obscure, the initiation of signaling events after interaction with asbestos fibers may govern transactivation of genes governing cell proliferation and transformation (4). Cell survival, proliferation, and progression of MMs are complex and may be related to overexpression of several autocrine growth factors, including insulin-like growth factor (5, 6), platelet-derived growth factor (7), fibroblast growth factor (8), transforming growth factor b (8), and hepatocyte growth factor/scatter factor (HGF) (9).Increased expression of Fos/Jun family members and activator protein-1 (AP-1) transactivation are observed in mesothelial cells after exposure to asbestos and erionite fibers in contrast to other nonpathogenic fibers and particles (10-12). In comparison to other fos/jun mRNAs, fos-related antigen 1 (fra-1) expression is more protracted and critical to expession of c-met and cd44 in a rat model of mesothelial cell transformation (1).Although HGF and its receptor, c-Met, are known to be involved in chemotaxis, growth, and invasion of a number of tumor types including MMs (13-15), the mechanisms of HGF/ Met signaling and their functional ramifications in MMs remain unclear. We previously reported that HGF stimula...

Acute promyelocytic leukemia (APL) is characterized by expression of promyelocytic leukemia (PML

Cancer is characterized by uncontrolled cell division resulting from multiple mutagenic events. Cancer chemoprevention strategies aim to inhibit or reverse these events using natural or synthetic pharmacologic agents. Ideally, this restores normal growth control mechanisms. Diverse classes of compounds have been identified with chemopreventive activity. What unites many of them is an ability to inhibit the cell cycle by specifically modulating key components. This delays division long enough for cells to respond to mutagenic damage. In some cases, damage is repaired and in others cellular damage is sufficient to trigger apoptosis. It is now known that pathways responsible for targeting G1 cyclins for proteasomal degradation can be engaged pharmacologically. Emergence of induced cyclin degradation as a target for cancer therapy and chemoprevention in pre-clinical models is discussed in this article. Evidence for cyclin D1 as a molecular pharmacologic target and biological marker for clinical response is based on experience of proof of principle trials.

New and effective treatment strategies are desperately needed for malignant mesothelioma (MM), an aggressive cancer with a poor prognosis. We have shown previously that acid-prepared mesoporous microspheres (APMS) are nontoxic after intrapleural or intraperitoneal (IP) administration to rodents. The purpose here was to evaluate the utility of APMS in delivering chemotherapeutic drugs to human MM cells in vitro and in two mouse xenograft models of MM. Uptake and release of doxorubicin (DOX) alone or loaded in APMS (APMS-DOX) were evaluated in MM cells. MM cell death and gene expression linked to DNA damage/repair were also measured in vitro. In two severe combined immunodeficient mouse xenograft models, mice received saline, APMS, DOX or APMS-DOX injected directly into subcutaneous (SC) MM tumors or injected IP after development of human MMs peritoneally. Other mice received DOX intravenously (IV) via tail vein injections. In comparison to DOX alone, APMS-DOX enhanced intracellular uptake of DOX, MM death and expression of GADD34 and TP73. In the SC MM model, 33 weekly SC injections of APMS-DOX or DOX alone significantly inhibited tumor volumes, and systemic DOX administration was lethal. In mice developing IP MMs, significant (p < 0.05) inhibition of mesenteric tumor numbers, weight and volume was achieved using IP administration of APMS-DOX at one-third the DOX concentration required after IP injections of DOX alone. These results suggest APMS are efficacious for the localized delivery of lower effective DOX concentrations in MM and represent a novel means of treating intracavitary tumors.

Strategies were developed by which mesoporous microparticles were modified on their external surfaces with tetraethylene glycol (TEG), a protein, or both, leaving the pore surfaces available for modification with a separate moiety, such as a dye. Only particles bifunctionally modified with both TEG and a cell-specific antibody were taken up specifically by a targeted cancer cell line. In contrast to similarly functionalized nanoparticles, endocytosed microparticles were not contained within a lysosome.

Silencing of Fra-1, a component of the dimeric transcription factor, activator protein-1 (AP-1), inhibits mRNA expression of c-met and cd44 in rat mesothelioma cells and is causally linked to maintenance of the transformed phenotype. However, the mechanisms of Fra-1 regulation and Fra-1 regulated gene expression in human malignant mesothelioma (MM) are unclear. We first show in a panel of human MM cells that Fra-1 mRNA expression in MM is complex and regulated by extracellular signal-regulated kinase (ERK1, ERK2), Src, and phosphatidyl-inositol-3-kinase (PI3K) pathways in a tumor-specific fashion. Cell lines with PI3K-dependent Fra-1 expression were SV40 positive and expressed the lowest basal Fra-1 levels. Levels of Fra-1 expression correlated with amounts of CD44 expression that were greater in simian virus 40 negative (SV40-) MM cells. Using dominant negative (dn), short hairpin (sh) and small interference (si) RNA constructs, we next demonstrate that expression of CD44, the principal hyaluronic receptor in MMs, correlates with Fra-expression in both simian virus 40 positive (SV40+) and SV40-MMs. Moreover, both Fra-1 and CD44 expression are linked to cell migration in SV40-MM cells. Lastly, in contrast to normal lung tissue, tissue microarrays revealed that Fra-1 was expressed in 33 of 34 human MMs, and that all CD44+ tumors were SV40-. These results suggest that Fra-1 is associated with cell migration in human MMs and that Fra-1 modulation of CD44 may govern migration of selected MMs.

Angiotensin-converting enzyme (ACE) inhibitors have been FDA-approved for treating refractory hypertension since 1981. Since then, clinical investigations support the benefits of ACE inhibition (ACE-I) in pathologies like congestive heart failure, myocardial infarction, diabetes mellitus, chronic renal insufficiency, and atherosclerotic cardiovascular disease. Both, clinical trials and animal models of type I and type II diabetes have shown that hyperactivity of the angiotensin II signaling pathway contributes to the development of diabetes and its complications, and that blockade of the renin-angiotensin system prevents new onset diabetes and reduces the risk of diabetic complications. Furthermore, ACE inhibitors are generally well tolerated and have few contraindications. This article describes ACE as a target molecule and gives an overview on the clinical evidence that supports the use of ACE inhibitors in diabetes.