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.

Thioredoxin-related regulation of NO/NOS activities.

The role of regulation of nitric oxide synthase (NOS) activity in mitigating oxidative stress in neonatal lungs and contributing to pulmonary vasodilation at birth is still unclear. Furthermore, it is known that, depending on interactions between the individual components of the mitogen-activated protein kinase (MAPK) signaling cascades, many biological consequences, including apoptosis, are initiated. Although the importance of nitric oxide (NO) in apoptosis is controversial and likely depends on NO concentrations and cell types, this highly reactive free radical can activate the p38 MAPK signal cascade. Recent studies have suggested that thioredoxin may play an important role as an effector for some of these functions. Thioredoxin is a major redox protein for many enzymes/transcription factors and is involved in cellular functions, such as viability, activation, and proliferation. In addition to its redox regulation, thioredoxin binds directly to the apoptosis signal-regulating kinase 1 (ASK1), thus inhibiting the activation of stress-induced MAPK signaling cascades that lead to apoptosis. Furthermore, NO produced from newly induced neuronal NOS was reported to induce expression of thioredoxin and several other genes for preconditioning-induced neuroprotection. Moreover, although exposure of endothelial cells to NO decreases NOS activity, this inhibition was shown to be reversed by thioredoxin. Finally, the correlation of expression of thioredoxin with endothelial NOS activity seems to suggest an important role played by this protein in perinatal changes of pulmonary artery functions. Therefore, thioredoxin may participate in the regulation of NOS activity and be involved in NO functions via multiple mechanisms.

3-amino thioacridone inhibits DNA synthesis and induce DNA damage in T-cell acute lymphoblastic leukemia (T-ALL) in a p16-dependent manner.

In T-cell Acute Lymphocytic Leukemia (T-ALL), the inhibitors of cyclin-dependent kinases (CDK) 4 and 6, p16 and p15, are inactivated almost universally at the DNA, RNA and protein levels. This suggests that CDK-targeting may be an effective therapeutic approach for T-ALL and other cancers. In this study, we tested 3 inhibitors of CDK4, 3-aminothioacridone (3-ATA), thioacridone (TA), and oxindole, for their effects on DNA synthesis and viability in primary T-ALL. Each compound was an effective inhibitor, with overall IC(50)s in similar ranges. In colony formation assay, leukemic cells were approximately 10-fold more sensitive to 3-ATA than normal bone marrow cells. When sorted by G1 protein status of T-ALL, p16(+), p15(+) or pRb(-) samples were significantly less sensitive to 3-ATA and TA, but not to oxindole, than p16(-), p15(-) or pRb(+) samples. There was no relationship of sensitivity with ARF expression. Despite their in vitro function as inhibitors of CDK4, 3-ATA did not inhibit pRb phosphorylation or cause G1 arrest, but did cause DNA damage and result in the induction and phosphorylation of p53. We conclude that 3-ATA efficacy can be predicted by p16 status in T-ALL, but the mechanism of action may be distinct from their in vitro ability to regulate CDK4 kinase activity

Identification of tumorigenic cells in Kras(G12D)-induced lung adenocarcinoma.

We established an inducible Kras(G12D)-driven lung adenocarcinoma in CCSP-rtTA/TetO-Cre/LSL-Kras(G12D) mice that enable pursuits of the cellular and molecular processes involved in Kras-induced tumorigenesis. To investigate the cellular origin of this cancer, we first report a strategy using fluorescence-activated cell sorting fractionation that could highly enrich bronchiolar Clara and alveolar type II cells, respectively. The EpCAM(+)MHCII(-) cells (bronchiolar origin) were more enriched with tumorigenic cells in generating secondary tumors than EpCAM(+)MHCII(+) cells (alveolar origin) in primary tumors that had been already initiated with oncogenic Kras activation. In addition, secondary tumors derived from EpCAM(+)MHCII(-) cells showed diversity of tumor locations compared with those derived from EpCAM(+)MHCII(+) cells. In the alveolar region, secondary tumors from EpCAM(+)MHCII(-) cells expressed not only bronchiolar epithelial marker, panCK, but also differentiation marker, proSPC, consistent with the notion that cancer-initiating cells display not only the abilities for self-renewal but also the features of differentiation to generate heterogeneous tumors with phenotypic diversity. Furthermore, high level of ERK1/2 activation and colony-forming ability as well as lack of Sprouty-2 expression were also observed in EpCAM(+)MHCII(-) cells. Therefore, these results suggest that bronchiolar Clara cells are the origin of cells and tumorigenesis for Kras(G12D)-induced neoplasia in the lungs.

Immunomodulatory and adjuvant activities of a polysaccharide extract of Ganoderma lucidum in vivo and in vitro.

We had isolated a high molecular weight polysaccharide fraction, designated as F3, and performed a comprehensive analysis of its immunomodulatory and adjuvant activities in vivo and in vitro. In vivo, F3-treated mice showed an increase in the number of dendritic cells as well as CD4, CD8, regulatory T, B, plasma, NK, and NKT cells in the spleen. F3 also elevated the levels of multiple cytokines and chemokines in the blood of mice. F3 displayed potent adjuvant activity for tetanus toxoid in the absence of alum and potentiated antibody responses to alum-containing tetanus toxoid in mice. In addition, F3 also boosted Th1 and Th2 response in vivo. In vitro, F3 induced the maturation of dendritic cells derived from human monocytes by upregulating CD40, CD54, CD80, CD83, CD86, and HLA-DR, enhanced mixed lymphocyte reaction, and stimulated the production of ten cytokines and six chemokines. In microarray analysis, expressions of 7688 genes were modulated in dendritic cells after treatment with F3, including cytokine and chemokine genes. These results provide F3 polysaccharide extract further insight into the mechanisms of action for these immunomodulatory and adjuvant activities of from Ganoderma lucidum and also offer preclinical evidence for its development as a vaccine adjuvant.

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.

The histone deacetylase inhibitor AN-9 has selective toxicity to acute leukemia and drug-resistant primary leukemia and cancer cell lines.

The novel prodrug of butyric acid, pivaloyloxymethyl butyrate (AN-9), a histone deacetylase inhibitor, shows great promise as an effective and relatively nontoxic anticancer agent for solid malignancies. However, little is known about its effects on hematopoietic malignancies. In this study, we show that 21 primary samples of acute leukemia were sensitive to the antiproliferative effects of AN-9, with a 50% inhibitory concentration (IC(50)) of 45.8 +/- 4.1 microM. In colony-forming assays, primary T-cell acute lymphoblastic leukemia (T-ALL) cells were 3-fold more sensitive to AN-9 than the normal hematopoietic progenitors, erythroid burst-forming units and granulocyte/monocyte colony-forming units. AN-9 induced apoptosis in the T-ALL cell line CEM. A common problem with cancer is chemoresistance, which is often typical of relapsed cancers. Remarkably, a T-ALL sample at diagnosis and an acute myeloid leukemia sample at relapse that were resistant to doxorubicin in vitro were sensitive to AN-9, with an IC(50) of 50 microM for both samples. More strikingly, samples from 2 infants with t(4;11) ALL obtained at diagnosis and relapse each were the most sensitive to AN-9, with IC(50) values of 25 microM and 17 microM, respectively. Furthermore, a doxorubicin-resistant clone of HL60, HL60/ADR, obtained by the transfection of the MDR-1 gene, was equally sensitive to AN-9 cytotoxicity as the parental cells. AN-9 induced the expression of p21 in an infant leukemia sample with 11q23 rearrangement, but not in T- or B-precursor ALL. Collectively, our results suggest that AN-9 is a selective agent for hematopoietic malignancies that can circumvent the mechanisms of chemoresistance limiting most conventional chemotherapy.