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BACKGROUND: Specific populations of highly tumorigenic cells are thought to exist in many human tumors,including pancreatic adenocarcinoma. However,the clinical significance of these tumor-initiating (ie,cancer stem) cells remains unclear. Aldehyde dehydrogenase (ALDH) activity can identify tumor-initiating cells and normal stem cells from several human tissues. We examined the prognostic significance and functional features of ALDH expression in pancreatic adenocarcinoma. METHODS: ALDH expression was analyzed by immunohistochemistry in 269 primary surgical specimens of pancreatic adenocarcinoma and examined for association with clinical outcomes and in paired primary tumors and metastatic lesions from eight pancreatic cancer patients who had participated in a rapid autopsy program. The clonogenic growth potential of ALDH-positive pancreatic adenocarcinoma cells was assessed in vitro by a colony formation assay and by tumor growth in immunodeficient mice (10-14 mice per group). Mesenchymal features of ALDH-positive pancreatic tumor cells were examined by using quantitative reverse transcription-polymerase chain reaction and an in vitro cell invasion assay. Gene expression levels and the invasive potential of ADLH-positive pancreatic cancer cells relative to the bulk cell population were examined by reverse transcription-polymerase chain reaction and an in vitro invasion assays,respectively. All statistical tests were two-sided. RESULTS: ALDH-positive tumor cells were detected in 90 of the 269 primary surgical specimens,and their presence was associated with worse survival (median survival for patients with ALDH-positive vs ALDH-negative tumors: 14 vs 18 months,hazard ratio of death = 1.28,95% confidence interval = 1.02 to 1.68,P = .05). Six (75%) of the eight patients with matched primary and metastatic tumor samples had ALDH-negative primary tumors,and in four (67%) of these six patients,the matched metastatic lesions (located in liver and lung) contained ALDH-positive cells. ALDH-positive cells were approximately five- to 11-fold more clonogenic in vitro and in vivo compared with unsorted or ALHD-negative cells,expressed genes consistent with a mesenchymal state,and had in vitro migratory and invasive potentials that were threefold greater than those of unsorted cells. CONCLUSIONS: ALDH expression marks pancreatic cancer cells that have stem cell and mesenchymal features. The enhanced clonogenic growth and migratory properties of ALDH-positive pancreatic cancer cells suggest that they play a key role in the development of metastatic disease that negatively affects the overall survival of patients with pancreatic adenocarcinoma. View Publication

PURPOSE: In vitro sensitivity to the proapoptotic receptor agonists dulanermin (rhApo2L/TRAIL) and drozitumab (DR5-agonist antibody) is strongly predicted by the expression of the O-glycosylation enzymes GALNT14 in non-small cell lung cancer (NSCLC) cell lines (among others) and of FUT3/6 in colorectal cancer (CRC) cell lines. We developed immunohistochemistry (IHC) assays that measure GALNT14 and FUT3/6 levels in archival formalin-fixed,paraffin-embedded human tumor tissue to determine marker prevalence in NSCLC and CRC tissue and to enable the future examination of these markers in clinical trials. EXPERIMENTAL DESIGN: GALNT14 or FUT3/6 ELISA-positive hybridoma clones were screened through IHC on cell pellets with known mRNA levels. The specificity of staining was examined in cell lines,normal tissue,and tumor tissue. RESULTS: GALNT14 and FUT3/6 IHC exhibited a golgi staining pattern and correlated with GALNT14 and FUT3/6 (but not GALNT2 and FUT4) mRNA expression levels in cell lines and normal tissues,suggesting specificity. GALNT14 and FUT3/6 H-scores were significantly higher in cell lines sensitive to dulanermin (P = 0.01 and P = 0.0004,respectively) and drozitumab (P = 0.03 and P textless 0.0001,respectively) versus resistant cell lines. GALNT14 and FUT3/6 H-scores varied widely,with approximately 45% of NSCLC samples exhibiting weak to moderate GALNT14 staining (H-score of at least 25) and 70% of CRC samples exhibiting moderate to strong FUT3/6 staining (H-score of at least 125). CONCLUSIONS: GALNT14 and FUT3/6 expression can be assessed in human tumors using sensitive and specific IHC assays. Both assays are being deployed in ongoing clinical trials of dulanermin and drozitumab to assess potential utility for patient selection. View Publication

Breast cancer stem cells are a group of undifferentiated cells with self-renewal and multidifferentiation potential. Chemotherapeutic and radiotherapeutic resistance,hypoxic resistance,high tumorigenicity,high cell invasion,and metastatic abilities are characteristics of these cells,which are responsible for breast cancer recurrence. Therefore,the correct sorting and identification of breast cancer stem cells is a primary step for research in this field. This article briefly describes the recent progress on sorting and identification technologies for breast cancer stem cells. Sorting technologies include the side population technique,technologies that depend on cell surface markers,ALDEFLUOR assays,and in situ detection. Identification technologies include mammosphere cultures,limited dilution in vitro,and in-vivo animal models. This review provides an important reference for breast cancer stem cell research,which will explore new methods for the treatment of patients with breast cancer. View Publication

We investigated functional relationships between microRNA 221/222 (miR-221/222) cluster and p27,a key regulator of cell cycle,in chronic lymphocytic leukemia (CLL). The enforced expression of miR-221/222 in the CLL cell line MEC1 induced a significant down-regulation of p27 protein and conferred a proliferative advantage to the transduced cells that exhibited faster progression into the S phase of the cell cycle. Accordingly,expression of miR-221/miR-222 and p27 was found to be inversely related in leukemic cells obtained from peripheral blood (PB) of 38 patients with CLL. Interestingly,when miR-221/222 and p27 protein were evaluated in different anatomic compartments (lymph nodes or bone marrow) of the same patients,increased expression of the 2 miRNAs became apparent compared with PB. This finding was paralleled by a low expression of p27. In addition,when CLL cells were induced in vitro to enter cell cycle (eg,with cytosine phosphate guanine oligodeoxynucleotide),a significant increase of miR-221/222 expression and a marked down-regulation of p27 protein were evident. These data indicate that the miR-221/222 cluster modulates the expression of p27 protein in CLL cells and lead to suggest that miR-221/222 and p27 may represent a regulatory loop that helps maintaining CLL cells in a resting condition. View Publication

The major goal of researchers and oncologists is to develop promising ground for novel therapeutic strategies to prevent recurrence or relapse of cancer. Recent evidences suggest that a subset of cells called cancer stem cells (CSCs) are present within the tumor mass which possess tumorigenic capacity and may be responsible for propagation,relapse,and metastatic dissemination. These cells have certain stem cell-like properties,e.g. quiescence,selfrenewal,asymmetric division,and multidrug resistance which allow them to drive tumor growth and evade conventional therapies. A number of markers and assays have been designed to isolate and characterize the CSC population from the bulk tumor. The objective now is to selectively target the CSCs in order to eliminate the tumor from root,overcoming the emergence of clones capable of evading traditional therapy. This approach may help in increasing the overall disease-free survival in some cancers. View Publication

A hallmark feature of glioblastoma is its strong self-renewal potential and immature differentiation state,which contributes to its plasticity and therapeutic resistance. Here,integrated genomic and biological analyses identified PLAGL2 as a potent protooncogene targeted for amplification/gain in malignant gliomas. Enhanced PLAGL2 expression strongly suppresses neural stem cell (NSC) and glioma-initiating cell differentiation while promoting their self-renewal capacity upon differentiation induction. Transcriptome analysis revealed that these differentiation-suppressive activities are attributable in part to PLAGL2 modulation of Wnt/beta-catenin signaling. Inhibition of Wnt signaling partially restores PLAGL2-expressing NSC differentiation capacity. The identification of PLAGL2 as a glioma oncogene highlights the importance of a growing class of cancer genes functioning to impart stem cell-like characteristics in malignant cells. View Publication

Cancer stem cells (CSCs) are a subpopulation of tumor cells with preferential tumor-initiating capacity and have been purported to be resistant to chemotherapy. It has been shown that breast CSC are,on average,enriched in patient tumors after combination neoadjuvant chemotherapy including docetaxel,doxorubicin,and cyclophosphamide (CPA). Here,we investigate the resistance of breast CSC to CPA alone in a xenograft model. CPA treatment led to a 48% reduction in tumor volume during a 2-week period. Cells bearing the CD44(+) CD24(-) phenotype were reduced by 90% (2.5% to 0.24%) in CPA-treated tumors,whereas cells with aldehyde dehydrogenase activity were reduced by 64% (4.7% to 1.7%). A subsequent functional analysis showed that CPA-treated tumors were impaired in their ability to form tumors,indicating loss of functional tumor-initiating activity. These results are consistent with a CSC phenotype that is sensitive to CPA and indicate that some patient CSC may not display the expected resistance to therapy. Deciphering the mechanism for this difference may lead to therapies to counteract resistance. View Publication

Glioblastoma multiforme (GBM) is the most common and aggressive form of primary brain tumor for which there is no curative treatment to date. Resistance to conventional therapies and tumor recurrence pose major challenges to treatment and management of this disease,and therefore new therapeutic strategies need to be developed. Previous studies by other investigators have shown that a subpopulation of GBM cells can grow as neurosphere-like cells when cultured in restrictive medium and exhibits enhanced tumor-initiating ability and resistance to therapy. We report here the identification of internalizing human single-chain antibodies (scFv) targeting GBM tumor sphere cells. We selected a large naive phage antibody display library on the glycosylation-dependent CD133 epitope-positive subpopulation of GBM cells grown as tumor spheres and identified internalizing scFvs that target tumor sphere cells broadly,as well as scFvs that target the CD133-positive subpopulation. These scFvs were found to be efficiently internalized by GBM tumor sphere cells. One scFv GC4 inhibited self-renewal of GBM tumor sphere cells in vitro. We have further developed a full-length human IgG1 based on this scFv,and found that it potently inhibits proliferation of GBM tumor sphere cells and GBM cells grown in regular nonselective medium. Taken together,these results show that internalizing human scFvs targeting brain tumor sphere cells can be readily identified from a phage antibody display library,which could be useful for further development of novel therapies that target subpopulations of GBM cells to combat recurrence and resistance to treatment. View Publication

In up to one-third of patients with acute myeloid leukemia,a C-terminal frame-shift mutation results in abnormal and abundant cytoplasmic accumulation of the usually nucleoli-bound protein nucleophosmin (NPM),and this is thought to function in cancer pathogenesis. Here,we demonstrate a gain-of-function role for cytoplasmic NPM in the inhibition of caspase signaling. The NPM mutant specifically inhibits the activities of the cell-death proteases,caspase-6 and -8,through direct interaction with their cleaved,active forms,but not the immature procaspases. The cytoplasmic NPM mutant not only affords protection from death ligand-induced cell death but also suppresses caspase-6/-8-mediated myeloid differentiation. Our data hence provide a potential explanation for the myeloid-specific involvement of cytoplasmic NPM in the leukemogenesis of a large subset of acute myeloid leukemia. View Publication

Killer cell lectin-like receptor F1 (KLRF1) is an activating C-type lectin-like receptor expressed on human NK cells and subsets of T cells. In this study,we show that activation-induced C-type lectin (AICL) is a unique KLRF1 ligand expressed on tumor cell lines of hematopoietic and non-hematopoietic origins. We screened a panel of human tumor cell lines using the KLRF1 reporter cells and found that several tumor lines expressed KLRF1 ligands. We characterized a putative KLRF1 ligand expressed on the U937 cell line. The molecular mass for the deglycosylated ligand was 28 kDa under non-reducing condition and 17 kDa under reducing condition,suggesting that the KLRF1 ligand is a homodimer. By expression cloning from a U937 cDNA library,we identified AICL as a KLRF1 ligand. We generated mAbs against AICL to identify the KLRF1 ligands on non-hematopoietic tumor lines. The anti-AICL mAbs stained the tumor lines that express the KLRF1 ligands and importantly the interaction of KLRF1 with the KLRF1 ligand on non-hematopoietic tumors was completely blocked by the two anti-AICL mAbs. Moreover,NK cell degranulation triggered by AICL-expressing targets was partially inhibited by the anti-AICL mAb. Finally,we demonstrate that AICL is expressed in human primary liver cancers. These results suggest that AICL is expressed on tumor cells of non-hematopoietic origins and raise the possibility that AICL may contribute to NK cell surveillance of tumor cells. View Publication

The importance of cancer metabolism has been appreciated for many years,but the intricacies of how metabolic pathways interconnect with oncogenic signaling are not fully understood. With a clear understanding of how metabolism contributes to tumorigenesis,we will be better able to integrate the targeting of these fundamental biochemical pathways into patient care. The mevalonate (MVA) pathway,paced by its rate-limiting enzyme,hydroxymethylglutaryl coenzyme A reductase (HMGCR),is required for the generation of several fundamental end-products including cholesterol and isoprenoids. Despite years of extensive research from the perspective of cardiovascular disease,the contribution of a dysregulated MVA pathway to human cancer remains largely unexplored. We address this issue directly by showing that dysregulation of the MVA pathway,achieved by ectopic expression of either full-length HMGCR or its novel splice variant,promotes transformation. Ectopic HMGCR accentuates growth of transformed and nontransformed cells under anchorage-independent conditions or as xenografts in immunocompromised mice and,importantly,cooperates with RAS to drive the transformation of primary mouse embryonic fibroblasts cells. We further explore whether the MVA pathway may play a role in the etiology of human cancers and show that high mRNA levels of HMGCR and additional MVA pathway genes correlate with poor prognosis in a meta-analysis of six microarray datasets of primary breast cancer. Taken together,our results suggest that HMGCR is a candidate metabolic oncogene and provide a molecular rationale for further exploring the statin family of HMGCR inhibitors as anticancer agents. View Publication

Small populations within an increasing array of solid tumors,labeled cancer stem cells (CSC) or tumor-initiating cells (TIC),have the ability to differentiate,self-renew,and replicate the original tumor in vivo. To date,these cells have been distinguished from the bulk-tumor population by the expression pattern of cell-surface proteins (e.g.,CD24,CD44,CD133) and cellular activities,such as the efflux of Hoechst dye or aldehyde dehydrogenase activity. Recent data have shown that these markers are inducible by exposure to anticancer agents; this finding highlights not only the potential fluidity of the CSC compartment,but also the functionality of these markers. The involvement of CD44 in invasion,adhesion,and metastasis,or the role of CD24 in modulation of src,FAK,and GLI1 are examples of these relevant roles. Instead of looking solely at the marker expression in these populations,we hope to clarify the biologically significant roles these markers and activities play in tumor progression,metastases,and as possible targets for therapy. View Publication