Chitosan nanoparticle-mediated delivery of miRNA-34a decreases prostate tumor growth in the bone and its expression induces non-canonical autophagy

While several new therapies are FDA-approved for bone-metastatic prostate cancer (PCa), patient survival has only improved marginally. Here, we report that chitosan nanoparticle-mediated delivery of miR-34a, a tumor suppressive microRNA that downregulates multiple gene products involved in PCa progression and metastasis, inhibited prostate tumor growth and preserved bone integrity in a xenograft model representative of established PCa bone metastasis. Expression of miR-34a induced apoptosis in PCa cells, and, in accord with downregulation of targets associated with PCa growth, including MET and Axl and c-Myc, also induced a form of non-canonical autophagy that is independent of Beclin-1, ATG4, ATG5 and ATG7. MiR-34a-induced autophagy is anti-proliferative in prostate cancer cells, as blocking apoptosis still resulted in growth inhibition of tumor cells. Thus, combined effects of autophagy and apoptosis are responsible for miR-34a-mediated prostate tumor growth inhibition, and have translational impact, as this non-canonical form of autophagy is tumor inhibitory. Together, these results provide a new understanding of the biological effects of miR-34a and highlight the clinical potential for miR-34a delivery as a treatment for bone metastatic prostate cancer

GWAS Meets Microarray: Are the Results of Genome-Wide Association Studies and Gene-Expression Profiling Consistent? Prostate Cancer as an Example

Genome-wide association studies (GWASs) and global profiling of gene expression (microarrays) are two major technological breakthroughs that allow hypothesis-free identification of candidate genes associated with tumorigenesis. It is not obvious whether there is a consistency between the candidate genes identified by GWAS (GWAS genes) and those identified by profiling gene expression (microarray genes).We used the Cancer Genetic Markers Susceptibility database to retrieve single nucleotide polymorphisms from candidate genes for prostate cancer. In addition, we conducted a large meta-analysis of gene expression data in normal prostate and prostate tumor tissue. We identified 13,905 genes that were interrogated by both GWASs and microarrays. On the basis of P values from GWASs, we selected 1,649 most significantly associated genes for functional annotation by the Database for Annotation, Visualization and Integrated Discovery. We also conducted functional annotation analysis using same number of the top genes identified in the meta-analysis of the gene expression data. We found that genes involved in cell adhesion were overrepresented among both the GWAS and microarray genes.We conclude that the results of these analyses suggest that combining GWAS and microarray data would be a more effective approach than analyzing individual datasets and can help to refine the identification of candidate genes and functions associated with tumor development

ALDH Activity Selectively Defines an Enhanced Tumor-Initiating Cell Population Relative to CD133 Expression in Human Pancreatic Adenocarcinoma

Multiple studies in recent years have identified highly tumorigenic populations of cells that drive tumor formation. These cancer stem cells (CSCs), or tumor-initiating cells (TICs), exhibit properties of normal stem cells and are associated with resistance to current therapies. As pancreatic adenocarcinoma is among the most resistant human cancers to chemo-radiation therapy, we sought to evaluate the presence of cell populations with tumor-initiating capacities in human pancreatic tumors. Understanding which pancreatic cancer cell populations possess tumor-initiating capabilities is critical to characterizing and understanding the biology of pancreatic CSCs towards therapeutic ends. cell populations were further examined for co-expression of CD44 and/or CD24. We demonstrate that unlike cell populations demonstrating low ALDH activity, as few as 100 cells enriched for high ALDH activity were capable of tumor formation, irrespective of CD133 expression. In direct xenograft tumors, the proportions of total tumor cells expressing ALDH and/or CD133 in xenograft tumors were unchanged through a minimum of two passages. We further demonstrate that ALDH expression among patients with pancreatic adenocarcinoma is heterogeneous, but the expression is constant in serial generations of individual direct xenograft tumors established from bulk human pancreatic tumors in NOD/SCID mice. phenotypes do not appear to significantly contribute to tumor formation at low numbers of inoculated tumor cells. ALDH expression broadly varies among patients with pancreatic adenocarcinoma and the apparent expression is recapitulated in serial generations of direct xenograft tumors in NOD/SCID. We have thus identified a distinct population of TICs that should lead to identification of novel targets for pancreatic cancer therapy

Nuclear PTEN-Mediated Growth Suppression Is Independent of Akt Down-Regulation

The tumor suppressor gene PTEN is a phosphoinositide phosphatase that is inactivated by deletion and/or mutation in diverse human tumors. Wild-type PTEN is expressed both in the cytoplasm and nucleus in normal cells, with a preferential nuclear localization in differentiated or resting cells. To elucidate the relationship between PTEN′s subcellular localization and its biologic activities, we constructed different PTEN mutants that targeted PTEN protein into different subcellular compartments. Our data show that the subcellular localization patterns of a PTEN (ΔPDZB) mutant versus a G129R phosphatase mutant were indistinguishable from those of wild-type PTEN. In contrast, the Myr-PTEN mutant demonstrated an enhanced association with the cell membrane. We found that nuclear PTEN alone is capable of suppressing anchorage-independent growth and facilitating G(1) arrest in U251MG cells without inhibiting Akt activity. Nuclear compartment-specific PTEN-induced growth suppression is dependent on possessing a functional lipid phosphatase domain. In addition, the down-regulation of p70S6K could be mediated, at least in part, through activation of AMP-activated protein kinase in an Akt-independent fashion. Introduction of a constitutively active mutant of Akt, Akt-DD, only partially rescues nuclear PTEN-mediated growth suppression. Our collective results provide the first direct evidence that PTEN can contribute to G(1) growth arrest through an Akt-independent signaling pathway

The combination of serum insulin, osteopontin, and hepatocyte growth factor predicts time to castration-resistant progression in androgen dependent metastatic prostate cancer- an exploratory study

BackgroundWe hypothesized that pretreatment serum levels of insulin and other serum markers would predict Progression-free survival (PFS), defined as time to castration-resistant progression or death, in metastatic androgen-dependent prostate cancer (mADPC).MethodsSerum samples from treatment-naïve men participating in a randomized phase 3 trial of ADT +/- chemotherapy were retrospectively analyzed using multiplex assays for insulin and multiple other soluble factors. Cox proportional hazards regression models were used to identify associations between individual factor levels and PFS.ResultsSixty six patients were evaluable (median age = 72 years; median prostate surface antigen [PSA] = 31.5 ng/mL; Caucasian = 86 %; Gleason score ≥8 = 77 %). In the univariable analysis, higher insulin (HR = 0.81 [0.67, 0.98] p = 0.03) and C-peptide (HR = 0.62 [0.39, 1.00]; p = 0.05) levels were associated with a longer PFS, while higher Hepatocyte Growth Factor (HGF; HR = 1.63 [1.06, 2.51] p = 0.03) and Osteopontin (OPN; HR = 1.56 [1.13, 2.15]; p = 0.01) levels were associated with a shorter PFS. In multivariable analysis, insulin below 2.1 (ln scale; HR = 2.55 [1.24, 5.23]; p = 0.011) and HGF above 8.9 (ln scale; HR = 2.67 [1.08, 3.70]; p = 0.027) levels were associated with longer PFS, while adjusted by OPN, C-peptide, trial therapy and metastatic volume. Four distinct risk groups were identified by counting the number of risk factors (RF) including low insulin, high HGF, high OPN levels, and low C-peptide levels (0, 1, 2, and 3). Median PFS was 9.8, 2.0, 1.6, and 0.7 years for each, respectively (p < 0.001).ConclusionPretreatment serum insulin, HGF, OPN, and C-peptide levels can predict PFS in men with mADPC treated with ADT. Risk groups based on these factors are superior predictors of PFS than each marker alone