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Somatic cells can be induced into pluripotent stem cells (iPSCs) with a combination of four transcription factors, Oct4/Sox2/Klf4/c-Myc or Oct4/Sox2/Nanog/LIN28. This provides an enabling platform to obtain patient-specific cells for various therapeutic and research applications. However, several problems remain for this approach to be therapeutically relevant due to drawbacks associated with efficiency and viral genome integration. Recently, it was shown that neural progenitor cells (NPCs) transduced with Oct4/Klf4 can be reprogrammed into iPSCs. However, NPCs express Sox2 endogenously, possibly facilitating reprogramming in the absence of exogenous Sox2. In this study, we identified a small-molecule combination, BIX-01294 and BayK8644, that enables reprogramming of Oct4/Klf4-transduced mouse embryonic fibroblasts, which do not endogenously express the factors essential for reprogramming. This study demonstrates that small molecules identified through a phenotypic screen can compensate for viral transduction of critical factors, such as Sox2, and improve reprogramming efficiency.

Oxidized low-density lipoprotein (OxLDL) is a well-known risk marker for cardiovascular diseases. OxLDL has shown a variety of proatherogenic properties in experiments performed in vitro. In addition, immunological studies using monoclonal antibodies have revealed the occurrence of OxLDL in vivo in atherosclerotic lesions and patients' plasma specimens. Resent clinical studies have indicated the prospective significance of plasma OxLDL measurements; however, the behavior and metabolism of OxLDL in vivo is poorly understood. The mechanism by which LDL is oxidized is not clear, and the modified structures of OxLDL are not yet fully understood, partly because OxLDL is a mixture of heterogeneously modified particles. Here, I discuss the recent studies on oxidative modifications in OxLDL and its clinical and pathological features.

Focal adhesion kinase (FAK) is a nonreceptor kinase that is overexpressed in many types of tumors. We developed a novel cancer-therapy approach, targeting the main autophosphorylation site of FAK, Y397, by computer modeling and screening of the National Cancer Institute (NCI) small molecule compounds database. More than 140,000 small molecule compounds were docked into the N-terminal domain of the FAK crystal structure in 100 different orientations that identified 35 compounds. One compound, 14 (1,2,4,5-benzenetetraamine tetrahydrochloride), significantly decreased viability in most of the cells to the levels equal to or higher than control FAK inhibitor 1a (2-[5-chloro-2-[2-methoxy-4-(4-morpholinyl)phenylamino]pyrimidin-4-ylamino]-N-methylbenzamide, TAE226) from Novartis, Inc. Compound 14 specifically and directly blocked phosphorylation of Y397-FAK in a dose- and time-dependent manner. It increased cell detachment and inhibited cell adhesion in a dose-dependent manner. Furthermore, 14 effectively caused breast tumor regression in vivo. Thus, targeting the Y397 site of FAK with 14 inhibitor can be effectively used in cancer therapy.

The transient receptor potential canonical (TRPC) family channels are proposed to be essential for store-operated Ca2+ entry in endothelial cells. Ca2+ signaling is involved in NF-kappaB activation, but the role of store-operated Ca2+ entry is unclear. Here we show that thrombin-induced Ca2+ entry and the resultant AMP-activated protein kinase (AMPK) activation targets the Ca2+-independent protein kinase Cdelta (PKCdelta) to mediate NF-kappaB activation in endothelial cells. We observed that thrombin-induced p65/RelA, AMPK, and PKCdelta activation were markedly reduced by knockdown of the TRPC isoform TRPC1 expressed in human endothelial cells and in endothelial cells obtained from Trpc4 knock-out mice. Inhibition of Ca2+/calmodulin-dependent protein kinase kinase beta downstream of the Ca2+ influx or knockdown of the downstream Ca2+/calmodulin-dependent protein kinase kinase beta target kinase, AMPK, also prevented NF-kappaB activation. Further, we observed that AMPK interacted with PKCdelta and phosphorylated Thr505 in the activation loop of PKCdelta in thrombin-stimulated endothelial cells. Expression of a PKCdelta-T505A mutant suppressed the thrombin-induced but not the TNF-alpha-induced NF-kappaB activation. These findings demonstrate a novel mechanism for TRPC channels to mediate NF-kappaB activation in endothelial cells that involves the convergence of the TRPC-regulated signaling at AMPK and PKCdelta and that may be a target of interference of the inappropriate activation of NF-kappaB associated with thrombosis.

Suramin is a polysulfonated polyaromatic symmetrical urea. It is currently used to treat African river blindness and African sleeping sickness. Suramin has also been extensively trialed recently to treat a number of other diseases, including many cancers. Here, we examine its modes of action and discuss its structure-activity relationships.

Cyclophosphamide (CYC) can control diffuse proliferative lupus nephritis (DPLN) by potent immunosuppression but remains associated with serious and life-threatening complications. Drugs that specifically target mediators of DPLN may help to reduce CYC dose and side effects. Monocyte chemoattractant protein (MCP-1)/CCL2 mediates monocyte and T cell recruitment in DPLN and Ccl2-specific l-enantiomeric RNA Spiegelmer mNOX-E36 neutralizes the biological effects of murine Ccl2 in vitro and in vivo. We injected MRL(lpr/lpr) mice with DPLN from 14 weeks of age with vehicle, weekly 30 mg/kg CYC (full dose), monthly 30 mg/kg CYC (one-fourth full dose), pegylated control Spiegelmer, pegylated anti-Ccl2 Spiegelmer (3/week), pegylated anti-Ccl2 Spiegelmer plus CYC one-fourth full dose and mycophenolate mofetil. At week 24, DPLN and autoimmune lung injury were virtually abolished with CYC full dose but not with CYC one-fourth full dose. The CYC one-fourth full dose/Spiegelmer combination was equipotent to CYC full dose on kidney and lung injury. CD3(+)CD4(-)CD8(-) and CD3(+)CD4(+)CD25(+) T cells and serum interleukin-12p40 and tumor necrosis factor-alpha levels were all markedly affected by CYC full dose but not by CYC one-fourth full dose. No additive effects of anti-Ccl2 Spiegelmer were noted on bone marrow colony-forming unit-granulocyte macrophage counts and 7/4(high) monocyte counts, lymphoproliferation, and spleen T cell depletion. In summary, anti-Ccl2 Spiegelmer permits 75% dose reduction of CYC for controlling DPLN and pneumonitis in MRL-Fas(lpr) mice, sparing suppressive effects of full-dose CYC on myelosuppression and T cell depletion. We propose anti-Ccl2 Spiegelmer therapy as a novel strategy to reduce CYC toxicity in the treatment of severe lupus.

We have demonstrated previously that cord blood CD133(+) cells isolated in the G(0) phase of the cell cycle are highly enriched for haematopoietic stem cell (HSC) activity, in contrast to CD133(+)G(1) cells. Here, we have analysed the phenotype and functional properties of this population in more detail. Our data demonstrate that a large proportion of the CD133(+)G(0) cells are CD38 negative (60.4%) and have high aldehyde dehydrogenase activity (75.1%) when compared with their CD133(+)G(1) counterparts (13.5 and 4.1%, respectively). This suggests that stem cell activity resides in the CD133(+)G(0) population. In long-term BM cultures, the CD133(+)G(0) cells generate significantly more progenitors than the CD34(+)G(0) population (Ptextless0.001) throughout the culture period. Furthermore, a comparison of CD133(+)G(0) versus CD133(+)G(1) cells revealed that multilineage reconstitution was obtained only in non-obese diabetic/SCID animals receiving G(0) cells. We conclude that CD133(+) cells in the quiescent phase of the cell cycle have a phenotype consistent with HSCs and are highly enriched for repopulating activity when compared with their G(1) counterparts. This cell population should prove useful for selection and manipulation in ex vivo expansion protocols.

We recently reported that the antineoplastic thiodioxopiperazine natural product chaetocin potently induces cellular oxidative stress, thus selectively killing cancer cells. In pursuit of underlying molecular mechanisms, we now report that chaetocin is a competitive and selective substrate for the oxidative stress mitigation enzyme thioredoxin reductase-1 (TrxR1) with lower K(m) than the TrxR1 native substrate thioredoxin (Trx; chaetocin K(m) = 4.6 +/- 0.6 microM, Trx K(m) = 104.7 +/- 26 microM), thereby attenuating reduction of the critical downstream ROS remediation substrate Trx at achieved intracellular concentrations. Consistent with a role for TrxR1 targeting in the anticancer effects of chaetocin, overexpression of the TrxR1 downstream effector Trx in HeLa cells conferred resistance to chaetocin-induced, but not to doxorubicin-induced, cytotoxicity. As the TrxR/Trx pathway is of central importance in limiting cellular reactive oxygen species (ROS)--and as chaetocin exerts its selective anticancer effects via ROS imposition--the inhibition of TrxR1 by chaetocin has potential to explain its selective anticancer effects. These observations have important implications not just with regard to the mechanism of action and clinical development of chaetocin and related thiodioxopiperazines, but also with regard to the utility of molecular targets within the thioredoxin reductase/thioredoxin pathway in the development of novel candidate antineoplastic agents.

The mechanisms underlying the decision of a stem or progenitor cell to either self-renew or differentiate are incompletely understood. To address the role of Myc in this process, we expressed different forms of the proto-oncogene Myc in multipotent neural progenitor cells (NPCs) using retroviral transduction. Expression of Myc in neurospheres increased the proportion of self-renewing cells fivefold, and 1% of the Myc-overexpressing cells, but none of the control cells, retained self-renewal capacity even under differentiation-inducing conditions. A Myc mutant (MycV394D) deficient in binding to Miz-1, did not increase the percentage of self-renewing cells but was able to stimulate proliferation of NPCs as efficiently as wild-type Myc, indicating that these two cellular phenomena are regulated by at least partially different pathways. Our results suggest that Myc, through Miz-1, enhances self-renewal of NPCs and influences the way progenitor cells react to the environmental cues that normally dictate the cellular identity of tissues containing self-renewing cells.

Recently it has been demonstrated that CD30 expression was rather specific for transformed than for normal human ES cells and therefore CD30 maybe suggested as a potential marker for human ES cells bearing chromosomal abnormalities. Using immunohistochemistry and RT-PCR analysis we examined �?¡D30 expression in 10 hESCs lines with normal and abberant karyotypes. All hESC lines expressed CD30 antigen and RNA in undifferentiated state whether cell line beared chromosomal abnormalities or not. In contrast to previous notions our data demonstrate that CD30 could be considered as marker of undifferentiated hESCs without respect to karyotype changes.

The CD31(+) subset of human naive CD4(+) T cells is thought to contain the population of cells that have recently emigrated from the thymus, while their CD31(-) counterparts have been proposed to originate from CD31(+) cells after homeostatic cell division. Naive T-cell maintenance is known to involve homeostatic cytokines such as interleukin-7 (IL-7). It remains to be investigated what role this cytokine has in the homeostasis of naive CD4(+) T-cell subsets defined by CD31 expression. We provide evidence that IL-7 exerts a preferential proliferative effect on CD31(+) naive CD4(+) T cells from adult peripheral blood compared with the CD31(-) subset. IL-7-driven proliferation did not result in loss of CD31 expression, suggesting that CD31(+) naive CD4(+) T cells can undergo cytokine-driven homeostatic proliferation while preserving CD31. Furthermore, IL-7 sustained or increased CD31 expression even in nonproliferating cells. Both proliferation and CD31 maintenance were dependent on the activation of phosphoinositide 3-kinase (PI3K) signaling. Taken together, our data suggest that during adulthood CD31(+) naive CD4(+) T cells are maintained by IL-7 and that IL-7-based therapies may exert a preferential effect on this population.

Earlier reports have suggested that the BCR/ABL oncogene, associated with chronic myeloid leukemia, induces a mutator phenotype; however, it is unclear whether this leads to long-term changes in chromosomes and whether the phenotype is found in primary chronic myelogeneous leukemia (CML) cells. We have addressed both these issues. BCR/ABL-expressing cell lines show an increase in DNA breaks after treatment with etoposide as compared to control cells. However, although BCR/ABL-expressing cell lines have an equivalent cell survival, they have an increase in chromosomal translocations after DNA repair as compared to control cells. This demonstrates that BCR/ABL expression decreases the fidelity of DNA repair. To see whether this is true in primary CML samples, normal CD34+ progenitor cells and CML progenitor cells were treated with etoposide. CML progenitor cells have equivalent survival but have an increase in DNA double-strand breaks (DSBs). Spectral karyotyping demonstrates new chromosomal translocations in CML cells, but not normal progenitor cells, consistent with error-prone DNA repair. Taken together, these data demonstrate that BCR/ABL enhances the accumulation of DSBs and alters the apoptotic threshold in CML leading to error-prone DNA repair.