Expression of Globo H and SSEA3 in breast cancer stem cells and the involvement of fucosyl transferases 1 and 2 in Globo H synthesis.

We examined the expression in breast cancer stem cells (BCSCs) of Globo H, a potential tumor-associated antigen for immunotherapy of epithelial cancers including breast cancer. Flow cytometry revealed Globo H expression in 25/41 breast cancer specimens (61.0%). Non-BCSCs from 25/25 and BCSCs from 8/40 (20%) expressed Globo H. We showed the expression of stage-specific embryonic antigen 3 (SSEA3), the pentasaccharide precursor of Globo H, in 31/40 (77.5%) tumors. Non-BCSCs from 29/40 [corrected] and BCSCs from 25/40 (62.5%) expressed SSEA3. Like Globo H, SSEA3 expression in normal tissues was predominately at the secretory borders of epithelium, where access to the immune system is restricted. Immunization of mice with Globo H-KLH and alpha-GalCer induced antibodies reactive with Globo H and SSEA3, suggesting that a Globo H-based vaccine will target tumor cells expressing Globo H or SSEA3. We next sought to reduce Globo H expression by siRNA targeting fucosyltransferase (FUT) 1 and 2, which mediate alpha-1,2 linkage of fucose to SSEA3 to generate Globo H. We showed both genes to be involved in the biosynthesis of Globo H. Moreover, FUT2 expression in BCSCs was significantly lower than in non-BCSCs harvested from a primary human breast cancer in NOD/SCID mouse, whereas FUT1 was slightly lower in BCSCs. Thus, the lower expression of Globo H in BCSCs may be attributed to less FUT2/FUT1, and to reduced SSEA3 in BCSCs compared with non-BCSCs. Our findings provide insight into further development of a Globo H-based vaccine and FUT1/FUT2-targeted therapy for breast cancer.

Tumor-localized ligation of CD3 and CD28 with systemic regulatory T-cell depletion induces potent innate and adaptive antitumor responses.

PURPOSE: Tumor-localized activation of immune cells by membrane-tethered anti-CD3 antibodies (CD3L) is under investigation to treat poorly immunogenic tumors. Here we sought to elucidate the mechanism of antitumor immunity elicited by CD3L. EXPERIMENTAL DESIGN: CD3L and CD86 were expressed on poorly immunogenic B16 melanoma cells (B16/3L86 cells) and the effect of various lymphocytes, including CD4(+) and CD8(+) T cells, natural killer T (NKT) cells, and regulatory T cells, on antitumor activity was investigated. RESULTS: B16/3L86 cells activated naïve T cells; suppressed tumor growth in subcutaneous, peritoneal, and metastasis models; and protected mice from rechallenge with B16 melanoma cells. However, in vivo antitumor activity against primary B16/3L86 tumors unexpectedly depended on NKT cells rather than CD4(+) or CD8(+) T cells. Treatment of mice with low-dose cyclophosphamide or anti-CD25 antibody to deplete regulatory T cells unmasked latent T-cell antitumor activity; the number of activated CD8(+) T cells in tumors increased and B16/3L86 tumors were completely rejected in a CD8(+) and CD4(+) T-cell-dependent fashion. Furthermore, fibroblasts expressing CD3L and CD86 suppressed the growth of neighboring B16 cancer cells in vivo, and direct intratumoral injection of adenoviral vectors expressing CD3L and CD86 or CD3L and a membrane-tethered anti-CD28 antibody significantly suppressed the growth of subcutaneous tumors. CONCLUSIONS: Tumor-located ligation of CD3 and CD28 can activate both innate (NKT cells) and adaptive (CD4(+) and CD8(+) T cells) responses to create a tumor-destructive environment to control tumor growth, but modulation of regulatory T cells is necessary to unmask local adaptive antitumor responses.

Caspase-3 enhances lung metastasis and cell migration in a protease-independent mechanism through the ERK pathway.

Caspase-3 is known as a cysteine protease that primarily executes the cell death program. However, some tumors express higher levels of caspase-3 in positive correlation with malignancy. Here, we showed that caspase-3 can promote tumor metastasis in a protease-independent mechanism. Ectopic expression of caspase-3 enhanced lung metastasis and cell motility of caspase-3 deficient MCF-7 cells. By contrast, caspase-3 siRNA reduced the invasiveness and metastasis ability of A549 cells that express high level of caspase-3. Moreover, caspase-3 induced ERK activation. Alteration of caspase-3 by introducing non-processable mutation at its cleavage site or treatment of caspase-3 inhibitor did not diminish the caspase-3-associated increases in ERK phosphorylation and cell migration. Confocal microscopy study showed that caspase-3 was not physically associated with ERK. Inhibiting ceramide formation by blockage of the ceramide synthase or acid sphingomyelinase activity resulted in significant reduction of ERK phosphorylation and cell migration. In summary, caspase-3 induces ERK activation through a ceramide-dependant, protease activity-independent mechanism, which represents a novel role of caspase-3 in tumor metastasis.

The Affinity of Elongated Membrane-Tethered Ligands Determines Potency of T Cell Receptor Triggering.

T lymphocytes are important mediators of adoptive immunity but the mechanism of T cell receptor (TCR) triggering remains uncertain. The interspatial distance between engaged T cells and antigen-presenting cells (APCs) is believed to be important for topological rearrangement of membrane tyrosine phosphatases and initiation of TCR signaling. We investigated the relationship between ligand topology and affinity by generating a series of artificial APCs that express membrane-tethered anti-CD3 scFv with different affinities (OKT3, BC3, and 2C11) in addition to recombinant class I and II pMHC molecules. The dimensions of membrane-tethered anti-CD3 and pMHC molecules were progressively increased by insertion of different extracellular domains. In agreement with previous studies, elongation of pMHC molecules or low-affinity anti-CD3 scFv caused progressive loss of T cell activation. However, elongation of high-affinity ligands (BC3 and OKT3 scFv) did not abolish TCR phosphorylation and T cell activation. Mutation of key amino acids in OKT3 to reduce binding affinity to CD3 resulted in restoration of topological dependence on T cell activation. Our results show that high-affinity TCR ligands can effectively induce TCR triggering even at large interspatial distances between T cells and APCs.

Surfection: a new platform for transfected cell arrays.

Efficient high-throughput expression of genes in mammalian cells can facilitate large-scale functional genomic studies. Towards this aim, we developed a simple yet powerful method to deliver genes into cells by cationic polymers on the surface of substrates. Transfection can be achieved by directly contacting nucleic acid-cell mixtures with the cationic substrates, e.g. polyethylenimine/collagen-coated wells. This single-step matrix-surface- mediated transfection method, termed 'surfection', can efficiently deliver multiple plasmids into cells and can successfully assay siRNA-mediated gene silencing. This technology represents the easiest method to transfer combinations of genes in large-scale arrays, and is a versatile tool for live-cell imaging and cell-based drug screening.

Suppressive function of low-dose deguelin on the invasion of oral cancer cells by downregulating tumor necrosis factor alpha-induced nuclear factor-kappa B signaling.

BACKGROUND: Deguelin has both antiproliferation and antimetastasis activities. However, high-dose deguelin elicits many undesired side effects. The purpose of this study was to investigate whether the low-dose deguelin can prevent the metastasis of oral cancer. METHODS: The dose effects of deguelin on metastasis of oral cancer cells were analyzed by in vitro invasion assay and an orthotropic xenograft mouse model. The involvement of tumor necrosis factor alpha (TNF-α)-induced nuclear factor-kappa B (NF-κB) signaling was examined by Western blot and reporter assay. RESULTS: Low-dose deguelin, which has minimal cytotoxicity, significantly inhibited the invasion and migration of oral cancer cells. These inhibitory effects of low-dose deguelin were mediated by suppressing TNF-α-induced activation of IκB kinase leading to the inhibition of IκB phosphorylation, NF-κB transcriptional activity, and matrix metalloproteinase-2 (MMP2) expression. The low-dose deguelin treatment significantly inhibited tumor growth and invasion without systemic toxicity. CONCLUSION: The low-dose deguelin suppressed the invasion and migration of oral cancer by downregulating TNF-α-induced NF-κB signaling. © 2015 Wiley Periodicals, Inc. Head Neck 38: E524-E534, 2016.

Synergistic effect of polyethylenimine and cationic liposomes in nucleic acid delivery to human cancer cells.

Polyethylenimine (PEI) and other polycations are good vehicles for transferring genes into the cells. In earlier reports, poly-L-lysine and protamine have been shown to improve gene delivery with cationic liposomes. In this study, PEI, combined with different cationic liposomes, was studied to determine the optimal conditions for gene delivery. The reporter genes, luciferase and green fluorescent protein, were used to transfect human HeLa, HepG2 and hepatoma 2.2.15 cells with various combinations of PEIs (0.8 and 25 kDa), poly-L-lysine (15-30 kDa), protamine and cationic liposomes. The highest expression level was achieved by using the combination of PEI 25 kDa (0.65 microg/microg of DNA, nitrogen-to-DNA phosphate (N/P) ratio=4.5) with 10 nmol of DOTAP-cholesterol (DOTAP-Chol, 1:1 w/w). This DNA complex formulation dramatically increased the luciferase expression 10- to 100-fold, which was much higher than those of other polycations alone, cationic liposomes alone or the combination. In addition, PEI/DOTAP-Chol combination had little cytotoxicity than DOTAP-Chol or other cationic liposomes alone. The effect of oligonucleotide (ODN) delivery facilitated by PEI and cationic liposomes was also studied in the hepatoma cell lines. We demonstrated an antisense ODN of p53 delivered by PEI/DOTAP-Chol combination effectively inhibited the biosynthesis of p53 protein in HepG2 (68% inhibiton) and 2.2.15 cells (43% inhibition). Thus, the large PEI could synergistically increase the transfection efficiency when combined with the cationic liposomes.

DDX3 as a strongest prognosis marker and its downregulation promotes metastasis in colorectal cancer.

BACKGROUND: Conflicting results regarding the role of DEAD-box polypeptide 3 (DDX3) are seen not only between cancer types but also within the same type of cancer. In this study, we aimed at clarifying the prognostic significance of DDX3 in patients of major cancer types through large cohort survival analysis and further investigated its effects on cancer progression. METHODS: Large cohort survival analysis of 7 cancer types, including colorectal cancer, breast cancer, lung cancer, head and neck cancer, liver cancer, glioblastoma, and ovarian cancer, was performed using public database at RNA level and was further confirmed by IHC analysis at protein level. Phenotype parameters of DDX3 knockdown colon cancer cells and the mechanism of DDX3 regulated cancer progression were investigated in vitro and in vivo. RESULTS: In large cohort survival analysis, DDX3 had a significant prognostic predictive power in colorectal cancer at both RNA and protein level. Patients with low DDX3 expression had poor prognosis and frequent distant metastasis. Knockdown of DDX3 enhanced the migration and invasion abilities of colon cancer cells and promoted tumor metastasis in vivo. Snail upregulation with decreased membranous E-cadherin expression and reduced cell aggregation were found after DDX3 downregulation. CONCLUSIONS: Our study revealed the strong prognostic effect of DDX3 on colorectal cancer among seven major cancer types through larger cohort survival analysis at RNA and protein level. Low DDX3 expression promotes Snail/E-cadherin pathway mediated cancer metastasis and poor clinical outcome in colorectal cancer patients.

Cisplatin selects for multidrug-resistant CD133+ cells in lung adenocarcinoma by activating Notch signaling.

Platinum-based chemotherapy is the first-line treatment for non-small cell lung cancer, but recurrence occurs in most patients. Recent evidence suggests that CD133(+) cells are the cause of drug resistance and tumor recurrence. However, the correlation between chemotherapy and regulation of CD133(+) cells has not been investigated methodically. In this study, we revealed that CD133(+) lung cancer cells labeled by a human CD133 promoter-driven GFP reporter exhibited drug resistance and stem cell characteristics. Treatment of H460 and H661 cell lines with low-dose cisplatin (IC(20)) was sufficient to enrich CD133(+) cells, to induce DNA damage responses, and to upregulate ABCG2 and ABCB1 expression, which therefore increased the cross-resistance to doxorubicin and paclitaxel. This cisplatin-induced enrichment of CD133(+) cells was mediated through Notch signaling as judged by increased levels of cleaved Notch1 (NICD1). Pretreatment with the γ-secretase inhibitor, N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-phenylglycine t-butyl ester (DAPT), or Notch1 short hairpin RNAs (shRNA) remarkably reduced the cisplatin-induced enrichment of CD133(+) cells and increased the sensitivity to doxorubicin and paclitaxel. Ectopic expression of NICD1 reversed the action of DAPT on drug sensitivity. Immunohistochemistry showed that CD133(+) cells were significantly increased in the relapsed tumors in three of six patients with lung cancer who have received cisplatin treatment. A similar effect was observed in animal experiments as cisplatin treatment increased Notch1 cleavage and the ratio of CD133(+) cells in engrafted tumors. Intratumoral injection of DAPT with cisplatin treatment significantly reduced CD133(+) cell number. Together, our results showed that cisplatin induces the enrichment of CD133(+) cells, leading to multidrug resistance by the activation of Notch signaling.

Adenylate kinase-4 is a marker of poor clinical outcomes that promotes metastasis of lung cancer by downregulating the transcription factor ATF3.

Biomarkers predicting metastatic capacity might assist the development of better therapeutic strategies for aggressive cancers such as lung cancer. In this study, we show that adenylate kinase-4 (AK4) is a progression-associated gene in human lung cancer that promotes metastasis. Analysis of published microarray data showed that AK4 was upregulated in lung adenocarcinoma compared with normal cells. High AK4 expression was associated with advanced stage, disease recurrence and poor prognosis. Loss of AK4 expression suppressed the invasive potential of lung cancer cell lines, whereas AK4 overexpression promoted invasion in vitro and in vivo. Mechanistically, the transcription factor ATF3 was identified as a pivotal regulatory target of AK4. Simultaneous reduction in AK4 and ATF3 expression abolished the inhibitory effects of ATF3 on invasion. ATF3 overexpression in AK4-overexpressing cells limits invasion activity. Furthermore, patients with high AK4 and low ATF3 expression showed unfavorable outcomes compared with patients with low AK4 and high ATF3 expression. Taken together, our findings indicated that AK4 promotes malignant progression and recurrence by promoting metastasis in an ATF3-dependent manner.

MicroRNA-122 plays a critical role in liver homeostasis and hepatocarcinogenesis.

MicroRNA-122 (miR-122), which accounts for 70% of the liver's total miRNAs, plays a pivotal role in the liver. However, its intrinsic physiological roles remain largely undetermined. We demonstrated that mice lacking the gene encoding miR-122a (Mir122a) are viable but develop temporally controlled steatohepatitis, fibrosis, and hepatocellular carcinoma (HCC). These mice exhibited a striking disparity in HCC incidence based on sex, with a male-to-female ratio of 3.9:1, which recapitulates the disease incidence in humans. Impaired expression of microsomal triglyceride transfer protein (MTTP) contributed to steatosis, which was reversed by in vivo restoration of Mttp expression. We found that hepatic fibrosis onset can be partially attributed to the action of a miR-122a target, the Klf6 transcript. In addition, Mir122a(-/-) livers exhibited disruptions in a range of pathways, many of which closely resemble the disruptions found in human HCC. Importantly, the reexpression of miR-122a reduced disease manifestation and tumor incidence in Mir122a(-/-) mice. This study demonstrates that mice with a targeted deletion of the Mir122a gene possess several key phenotypes of human liver diseases, which provides a rationale for the development of a unique therapy for the treatment of chronic liver disease and HCC.

BO-0742, a derivative of AHMA and N-mustard, has selective toxicity to drug sensitive and drug resistant leukemia cells and solid tumors.

This is a preclinical study of BO-0742, a derivative of 3-(9-acridinylamino)-5-hydroxymethyl-aniline (AHMA) and N-mustard, as an anti-cancer agent. MTS assays revealed a broad spectrum of anti-cancer activities in vitro, with the greatest cytotoxicity against leukemia and neuroblastoma including those with drug resistant characteristics, and a good therapeutic index with leukemia being 10-40 times more sensitive to BO-0742 than hematopoietic progenitors. Administration of BO-0742 at an optimal dose schedule based on its pharmacokinetics significantly suppressed the growth of xenografts of human breast and ovarian cancers in mice. Thus, BO-0742 is a potent anti-cancer agent worthy of further clinical development.

Enhanced gene delivery to HER-2-overexpressing breast cancer cells by modified immunolipoplexes conjugated with the anti-HER-2 antibody.

Cationic liposome-mediated gene delivery to tumors has met with only limited success due to the low transfection efficiency and lack of target specificity. We developed a gene delivery system for HER-2-overexpressing cells by adding modified anti-HER-2 Fab' fragments to liposome/DNA complexes (lipoplexes). The modified anti-HER-2-Fab' was conjugated to liposomes containing cationic lipids such as 1,2-dioleoyl-3-(trimethylammonium) propane and cholesterol (1:1 w/w) using a maleimido-polyethyleneglycol-3400-1,2-dioleoyl-3-sn-phosphatidylethanolamine linker. The specific modification constricted the sizes of these immunolipoplexes to a range of 0.3- 0.7 microm, and they remained stable for a longer duration of time compared to the lipoplex controls (0.8-3.2 microm at 4 h). In addition, a 10-fold increase in luciferase activity was achieved after transfecting human breast cancer SK-BR3 cells with immunolipoplexes as compared to the control lipoplexes. Flow cytometry analysis demonstrated that 80% of SK-BR3 cells expressed the green fluorescent protein (GFP) 48 h after being transfected with immunolipoplexes, while only 40% of those with control lipoplexes and 3% of those with naked DNA alone expressed GFP. Furthermore, the anti-HER-2 immunolipoplexes showed specific enhancement of transfection efficiency in HER-2-overexpressing SK-BR3 cells (a 6-fold increase in luciferase activity) but not in HER-2-negative MCF-7 breast cancer cells. The enhancement of gene delivery by anti-HER-2 immunoliposomes was not affected by the presence of serum. These results demonstrate the feasibility of improving target-specific gene delivery to HER-2-overexpressing cells by insertion of lipid-modified anti-HER-2-Fab' into the preformed liposomes.