Scientific Resources

BACKGROUND To evaluate the anticancer efficacy of the combination of epigenetic modifiers and cisplatin in human ovarian cancer. METHODS The effect of trichostatin A (TSA) and 5-aza-2'-deoxycytidine alone or in combination with low-dose cisplatin was evaluated on human ovarian cancer cell lines in vitro. We measured drug interaction by MTS assay,migration by transwell assay,expression of epithelial to mesenchymal transition (EMT) markers (Twist,Snail,Slug,E-cadherin,and N-cadherin),pluripotency markers (Oct4,Sox2,and Nanog),and epigenetic markers (DNMT3A,LSD1 and H3K4me2,H3K4me3,H3K9me2,and H3K9me3) by western blot,and the impact on and characteristics of spheroid growth when exposed to these drugs. Mouse xenografts were used to evaluate the anticancer effect of sequential drug treatment. RESULTS Combination treatment had greater efficacy than single drugs and significantly suppressed cell viability,migration,and spheroid formation and growth. Sequential treatment of cisplatin (1 mg kg(-1)) followed by TSA (0.3 mg kg(-1)) significantly suppressed tumorigenicity of HEY xenografts through inhibition of EMT and decreased pluripotency of ovarian cancer cells. CONCLUSION Epigenetic modifiers potentiate the anticancer efficacy of low-dose cisplatin in ovarian cancer through regulation of EMT and pluripotency,and may provide a promising treatment for ovarian cancer patients. View Publication

The antitumor activity of LPS was first described by Dr. William Coley. However,its role in lung cancer remains unclear. The aim of our study was to elucidate the dose-dependent effects of LPS (0.1-10 μg/mouse) in a mouse model of B16-F10-induced metastatic lung cancer. Lung tumor growth increased at 3 and 7 d after the administration of low-dose LPS (0.1 μg/mouse) compared with control mice. This was associated with an influx of plasmacytoid dendritic cells (pDCs),regulatory T cells,myeloid-derived suppressor cells,and CD8(+) regulatory T cells. In contrast,high-dose LPS (10 μg/mouse) reduced lung tumor burden and was associated with a greater influx of pDCs,as well as a stronger Th1 and Th17 polarization. Depletion of pDCs during low-dose LPS administration resulted in a decreased lung tumor burden. Depletion of pDCs during high-dose LPS treatment resulted in an increased tumor burden. The dichotomy in LPS effects was due to the phenotype of pDCs,which were immunosuppressive after the low-dose LPS,and Th1- and T cytotoxic-polarizing cells after the high-dose LPS. Adoptive transfer of T cells into nude mice demonstrated that CD8(+) T cells were responsible for pDC recruitment following low-dose LPS administration,whereas CD4(+) T cells were required for pDC influx after the high-dose LPS. In conclusion,our data suggest differential effects of low-dose versus high-dose LPS on pDC phenotype and tumor progression or regression in the lungs of mice. View Publication

Most forms of chemotherapy employ mechanisms involving induction of oxidative stress,a strategy that can be effective due to the elevated oxidative state commonly observed in cancer cells. However,recent studies have shown that relative redox levels in primary tumors can be heterogeneous,suggesting that regimens dependent on differential oxidative state may not be uniformly effective. To investigate this issue in hematological malignancies,we evaluated mechanisms controlling oxidative state in primary specimens derived from acute myelogenous leukemia (AML) patients. Our studies demonstrate three striking findings. First,the majority of functionally defined leukemia stem cells (LSCs) are characterized by relatively low levels of reactive oxygen species (termed ROS-low"). Second� View Publication

Breast cancer is a heterogenous disease,composed of tumour cells with differing gene expressions and phenotypes. Very few antigens have been identified and a better understanding of tumour initiating-cells as targets for therapy is critically needed. Recently,a rare subpopulation of cells within tumours has been described with the ability to: (i) initiate and sustain tumour growth; (ii) resist traditional therapies and allow for secondary tumour dissemination; and (iii) display some of the characteristics of stem cells such as self-renewal. These cells are termed tumour-initiating cells or cancer stem cells,or alternatively,in the case of breast cancer,breast cancer stem cells. Previous studies have demonstrated that breast cancer stem cells can be enriched for in tumoursphere" culture. Proteomics represents a novel way to investigate protein expression between cells. We hypothesise that characterisation of the proteome of the breast cancer line MCF-7 tumourspheres compared to adherent/differentiated cells identifies proteins of novel interest for further isolating or targeting breast cancer stem cells. We present evidence that: (i) the proteome of adherent cells is different to the proteome of cells grown in sphere medium from either early passage (passage 2) or late passage (passage 5) spheres; (ii) that spheres are enriched in expression of a variety of tumour-relevant proteins (including MUC1 and Galectin-3); and (iii) that targeting of one of these identified proteins (galectin-3) using an inhibitor (N-acetyllactosamine) decreases sphere formation/self-renewal of MCF-7 cancer stem cells in vitro and tumourigenicity in vivo. Hence� View Publication

Ovarian cancer is the most lethal gynaecologic cancer,in large part because of its early dissemination and rapid development of chemotherapy resistance. Spheroids are clusters of tumor cells found in the peritoneal fluid of patients that are thought to promote this dissemination. Current models suggest that spheroids form by aggregation of single tumor cells shed from the primary tumor. Here,we demonstrate that spheroids can also form by budding directly as adherent clusters from a monolayer. Formation of budded spheroids correlated with expression of vimentin and lack of cortical E-cadherin. We also found that compared to cells grown in monolayers,cells grown as spheroids acquired progressive resistance to the chemotherapy drugs Paclitaxel and Cisplatin. This resistance could be completely reversed by dissociating the spheroids. Our observations highlight a previously unappreciated mode of spheroid formation that might have implications for tumor dissemination and chemotherapy resistance in patients,and suggest that this resistance might be reversed by spheroid dissociation. View Publication

Findings from studies on stem cells have been applied to cancer stem cell (CSC) research,but little is known about the relationship between ES cell-related cell surface markers and CSCs. In this study,we focused on stage-specific embryonic antigen 3 (SSEA-3),a marker of mesenchymal stem cells and Muse cells in colorectal cancer (CRC). Expression of SSEA-3 in human CRC cell lines and clinical specimens,specifically the relationship of SSEA-3 expression and the representative CSC markers (CD44,CD166,ALDH,CD24 and CD26) as well as with mesenchymal stem cell/Muse cell marker (CD105) were assessed. To characterize SSEA-3-expressing cells,tumorigenicity,sphere formation ability,expression of iPS genes (Oct4,NANOG,SOX2 and c-Myc),cell proliferation and cell cycle status were assessed. SSEA-3 expression was identified in Caco-2,DLD-1,HT-29,SW480 and HCT116,but not in CaR-1 cells. No significant relationship between SSEA-3 and other stem cell markers was detected. SSEA-3+ cells showed increased tumorigenicity in vivo,but lower sphere formation ability in vitro than SSEA-3-. iPS gene expression was not correlated with SSEA-3 expression status. SSEA-3+ cells showed higher proliferative ability than SSEA-3- through enhanced cell cycles by decreased expression of p21Cip1/Waf1 and p27Kip1. Immunofluorescence analysis in clinical specimens indicated that expression of SSEA-3 is limited to stromal cells in normal mucosa but broad in poorly differentiated adenocarcinoma. These observations indicated that SSEA-3+ cells in CRC have immature phenotype but decreased self-renewal ability and may function as tumor transient amplifying cells or delayed contributing tumor-initiating cells. View Publication

Extrinsic signaling cues in the microenvironment of acute myelogenous leukemia (AML) contribute to disease progression and therapy resistance. Yet,it remains unknown how the bone marrow niche in which AML arises is subverted to support leukemic persistence at the expense of homeostatic function. Exosomes are cell membrane-derived vesicles carrying protein and RNA cargoes that have emerged as mediators of cell-cell communication. In this study,we examined the role of exosomes in developing the AML niche of the bone marrow microenvironment,investigating their biogenesis with a focus on RNA trafficking. We found that both primary AML and AML cell lines released exosome-sized vesicles that entered bystander cells. These exosomes were enriched for several coding and noncoding RNAs relevant to AML pathogenesis. Furthermore,their uptake by bone marrow stromal cells altered their secretion of growth factors. Proof-of-concept studies provided additional evidence for the canonical functions of the transferred RNA. Taken together,our findings revealed that AML exosome trafficking alters the proliferative,angiogenic,and migratory responses of cocultured stromal and hematopoietic progenitor cell lines,helping explain how the microenvironmental niche becomes reprogrammed during invasion of the bone marrow by AML. View Publication

We investigated the expression status of periostin in breast cancer stem cells and its clinical implications in order to lay a foundation for managing breast cancer. CD44+/CD24-/line- tumor cells (CSC) from clinical specimens were sorted using flow cytometry. Periostin expression status was detected in CSC cells and 1,086 breast cancer specimens by Western blot and immunohistochemistry staining,with the CSC ratio determined by immunofluorescence double staining. The relationship between the periostin protein and clinico-pathological parameters and prognosis was subsequently determined. As a result,CSC cells are more likely to generate new tumors in mice and cell microspheres that are deficient in NOD/SCID compared to the control group. Periostin protein was expressed higher in CSC cells compared to the control cells and was found to be related to CSC chemotherapy resistance. Moreover,periostin expression was found to be related to the CSC ratio in 1,086 breast cancer specimens (P = 0.001). In total,334 (30.76%) of the 1,086 breast cases showed high periostin expression. After universal and Spearman regression correlation analysis,periostin was observed to be related to histological grade,CSC ratio,lymph node metastasis,tumor size,and triple-negative breast cancer (all Ptextless0.05). Furthermore,periostin was shown to attain a significantly more distant bone metastasis and worse disease-specific survival than those with none or low-expressed periostin protein (P = 0.001). In the Cox regression test,periostin protein was detected as an independent prognostic factor (P = 0.001). In conclusion,periostin was found to be related to the CSC and an independent prognostic factor for breast cancer. It is also perhaps a potential target to breast cancer. View Publication

INTRODUCTION: Retinoic acid signaling plays key roles in embryonic development and in maintaining the differentiated status of adult tissues. Recently,the nuclear retinoic acid receptor (RAR) isotypes α,β and γ were found to play specific functions in the expansion and differentiation of the stem compartments of various tissues. For instance,RARγ appears to be involved in stem cell compartment expansion,while RARα and RARβ are implicated in the subsequent cell differentiation. We found that over-expressing c-Myc in normal mouse mammary epithelium and in a c-Myc-driven transgenic model of mammary cancer,disrupts the balance between RARγ and RARα/β in favor of RARγ. METHODS: The effects of c-Myc on RAR isotype expression were evaluated in normal mouse mammary epithelium,mammary tumor cells obtained from the MMTV-Myc transgenic mouse model as well as human normal immortalized breast epithelial and breast cancer cell lines. The in vivo effect of the RARα-selective agonist 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carboxamido]benzoic acid (Am580) was examined in the MMTV-Myc mouse model of mammary tumorigenesis. RESULTS: Modulation of the RARα/β to RARγ expression in mammary glands of normal mice,oncomice,and human mammary cell lines through the alteration of RAR-target gene expression affected cell proliferation,survival and tumor growth. Treatment of MMTV-Myc mice with the RARα-selective agonist Am580 led to significant inhibition of mammary tumor growth (˜90%,Ptextless0.001),lung metastasis (Ptextless0.01) and extended tumor latency in 63% of mice. Immunocytochemical analysis showed that in these mice,RARα responsive genes such as Cyp26A1,E-cadherin,cellular retinol-binding protein 1 (CRBP1) and p27,were up-regulated. In contrast,the mammary gland tumors of mice that responded poorly to Am580 treatment (37%) expressed significantly higher levels of RARγ. In vitro experiments indicated that the rise in RARγ was functionally linked to promotion of tumor growth and inhibition of differentiation. Thus,activation of the RARα pathway is linked to tumor growth inhibition,differentiation and cell death. CONCLUSIONS: The functional consequence of the interplay between c-Myc oncogene expression and the RARγ to RARα/β balance suggests that prevalence of RARγ over-RARα/β expression levels in breast cancer accompanied by c-Myc amplification or over-expression in breast cancer should be predictive of response to treatment with RARα-isotype-specific agonists and warrant monitoring during clinical trials. View Publication

BACKGROUND: Recent data suggest that cancer stem cells (CSCs) play an important role in cancer,as these cells possess enhanced tumor-forming capabilities and are responsible for relapses after apparently curative therapies have been undertaken. Hence,novel cancer therapies will be needed to test for both tumor regression and CSC targeting. The use of oncolytic vaccinia virus (VACV) represents an attractive anti-tumor approach and is currently under evaluation in clinical trials. The purpose of this study was to demonstrate whether VACV does kill CSCs that are resistant to irradiation and chemotherapy. METHODS: Cancer stem-like cells were identified and separated from the human breast cancer cell line GI-101A by virtue of increased aldehyde dehydrogenase 1 (ALDH1) activity as assessed by the ALDEFLUOR assay and cancer stem cell-like features such as chemo-resistance,irradiation-resistance and tumor-initiating were confirmed in cell culture and in animal models. VACV treatments were applied to both ALDEFLUOR-positive cells in cell culture and in xenograft tumors derived from these cells. Moreover,we identified and isolated CD44(+)CD24(+)ESA(+) cells from GI-101A upon an epithelial-mesenchymal transition (EMT). These cells were similarly characterized both in cell culture and in animal models. RESULTS: We demonstrated for the first time that the oncolytic VACV GLV-1h68 strain replicated more efficiently in cells with higher ALDH1 activity that possessed stem cell-like features than in cells with lower ALDH1 activity. GLV-1h68 selectively colonized and eventually eradicated xenograft tumors originating from cells with higher ALDH1 activity. Furthermore,GLV-1h68 also showed preferential replication in CD44(+)CD24(+)ESA(+) cells derived from GI-101A upon an EMT induction as well as in xenograft tumors originating from these cells that were more tumorigenic than CD44(+)CD24(-)ESA(+) cells. CONCLUSIONS: Taken together,our findings indicate that GLV-1h68 efficiently replicates and kills cancer stem-like cells. Thus,GLV-1h68 may become a promising agent for eradicating both primary and metastatic tumors,especially tumors harboring cancer stem-like cells that are resistant to chemo and/or radiotherapy and may be responsible for recurrence of tumors. View Publication

Although inactivation of the PTEN gene has been implicated in the development of resistance to the HER2 targeting antibody trastuzumab,the mechanisms mediating this resistance remain elusive. We generated trastuzumab resistant cells by knocking down PTEN expression in HER2 overexpressing breast cancer cell lines and demonstrate that development of trastuzumab resistance in these cells is mediated by activation of an IL6 inflammatory feedback loop leading to expansion of the cancer stem cell (CSC) population. Long term trastuzumab treatment generates highly enriched CSCs which display an EMT phenotype secreting over 100-fold more IL6 than parental cells. An IL6 receptor antibody interrupted this inflammatory feedback loop reducing the cancer stem cell population resulting in decreased tumor growth and metastasis in mouse xenographs. These studies demonstrate that trastuzumab resistance may be mediated by an IL6 inflammatory loop and suggest that blocking this loop may provide alternative strategy to overcome trastuzumab resistance. View Publication

PURPOSE: We have previously demonstrated that in pancreatic ductal adenocarcinoma (PDAC)-derived cell lines,the common Src family kinase inhibitors PP2 and PP1 effectively inhibited morphologic alterations associated with TGFβ1-mediated epithelial-to-mesenchymal transition (EMT) by blocking the kinase activity of the TGF-β type I receptor ALK5 rather than Src (Ungefroren et al. in Curr Cancer Drug Targets 11:524,2011). In this report,the ability of PP2 and PP1,the more specific Src inhibitor SU6656,and the ALK5 inhibitor SB431542 to functionally block TGF-β1-dependent EMT and cell motility in established PDAC (Panc-1,Colo 357) and primary NSCLC (Tu459) cell lines were investigated. METHODS: The effects of PP2,PP1,SU6656,and SB431542 on TGF-β1-dependent cell scattering/EMT,cell migration/invasion,and expression of invasion-associated genes were measured by using the real-time cell analysis assay on the xCELLigence system and quantitative real-time RT-PCR,respectively. RESULTS: In all three cell lines tested,PP1,PP2,and SB431542 effectively blocked TGF-β1-induced cell scattering/EMT,migration,and invasion and in Colo 357 cells inhibited the induction of the invasion-associated MMP2 and MMP9 genes. In contrast,SU6656 only blocked TGF-β1-induced invasion in Panc-1 and Tu459 but not Colo 357 cells. PP1,and to a greater extent PP2,also inhibited the high spontaneous migratory activity of Panc-1 cells expressing a kinase-active ALK5 mutant. CONCLUSIONS: These data provide evidence that PP2 and PP1 are powerful inhibitors of TGF-β-induced cell migration and invasion in vitro and directly target ALK5. Both agents may be useful as dual TGF-β/Src inhibitors in experimental therapeutics to prevent metastatic spread in late-stage PDAC and NSCLC. View Publication