[Resting-state functional MRI studies of amyotrophic lateral sclerosis patients with various levels of cognitive impairment]

Objective: To characterize the brain functional changes of amyotrophic lateral sclerosis (ALS) patients with various levels of cognitive impairment as measured by resting-state functional MRI (RS-fMRI). Methods: From September 2013 to March 2017, a total of 55 patients diagnosed with ALS in Peking Union Medical College Hospital and 20 healthy controls (HCs) were included in this study, and all participants underwent neuropsychological assessments and diffusion tensor imaging scans. According to their cognitive performance, ALS patients were further subclassified into ALS with normal cognition (ALS-Cn, n=27), those with cognitive impairment (ALS-Ci, n=17) and ALS-FTD (n=11). Comparisons of fractional amplitude of low frequency fluctuation (fALFF) value and regional homogeneity (ReHo) value were conducted among the 4 subgroups. Results: The fALFF showed significant differences in bilateral frontal lobe, left temporal lobe and cingulate gyrus, (P<0.001, uncorrected) and the ReHo showed significant differences in left frontal lobe, right temporal lobe and left cingulate gyrus (P<0.001, FDR corrected). The differences mainly stemmed from that patients with ALS-FTD showed decreased fALFF and ReHo in these areas when compared to the other three groups, especially in relation to HCs, mainly locating in left prefrontal lobe and anterior cingulate cortex. The whole-brain comparisons of fALFF and ReHo between ALS-Ci, ALS-Cn and HCs revealed no significant difference (P<0.001, uncorrected). Conclusion: Hypoactivities are detected in extramotor areas in patients with ALS-FTD. RS-fMRI is helpful in investigating the pathophysiologic mechanism of cognitive impairment in ALS.

The integrated spintronic functionalities of an individual high-spin state spin-crossover molecule between graphene nanoribbon electrodes

The spin-polarized transport properties of a high-spin-state spin-crossover molecular junction with zigzag-edge graphene nanoribbon electrodes have been studied using density functional theory combined with the nonequilibrium Green's-function formalism. The molecular junction presents integrated spintronic functionalities such as negative differential resistance behavior, spin filter and the spin rectifying effect, associated with the giant magnetoresistance effect by tuning the external magnetic field. Furthermore, the transport properties are almost unaffected by the electrode temperature. The microscopic mechanism of these functionalities is discussed. These results represent a step toward multifunctional molecular spintronic devices on the level of the individual spin-crossover molecule.

Regulation of inflammation by the NF-κB pathway in ovarian cancer stem cells

PROBLEM

The NFκB pathway is a major source of pro-inflammatory cytokines, which may contribute to cancer chemoresistance. We showed that constitutive NFκB activity is characteristic of the ovarian cancer stem cells (OCSCs). The aim of this study is to determine whether the inhibition of NFκB by Eriocalyxin B (EriB) in the OCSCs may induce cell death in otherwise chemoresistant cells.

METHODS

OCSCs and mature ovarian cancer cells (mOCCs) were treated with increasing concentrations of EriB. Cell viability was measured using the Celltiter 96 assay, and caspase activity was quantified using Caspase-Glo™ assay. Cytokine levels were quantified using xMAP technology.

RESULTS

EriB decreased the percent of viable cells in all cultures tested with GI(50) of 0.5-1 μm after 48 hrs of treatment. The intracellular changes associated with EriB-induced cell death are: (i) inhibition of NF-κB activity; (ii) decreased cytokine production; (iii) activation of caspases; and (iv) down-regulation of XIAP. In addition, EriB is able to sensitize OCSCs to TNFα and FasL-mediated cell death.

CONCLUSION

Inhibition of the NFκB pathway induces cell death in the OCSCs. Because the OCSCs may represent the source of recurrence and chemoresistance, the use of NFκB inhibitors like EriB may prevent recurrence in patients with ovarian cancer.

Clostridium perfringens enterotoxin carboxy-terminal fragment is a novel tumor-homing peptide for human ovarian cancer

Background

Development of innovative, effective therapies against recurrent/chemotherapy-resistant ovarian cancer remains a high priority. Using high-throughput technologies to analyze genetic fingerprints of ovarian cancer, we have discovered extremely high expression of the genes encoding the proteins claudin-3 and claudin-4.

Methods

Because claudin-3 and -4 are the epithelial receptors for Clostridium perfringens enterotoxin (CPE), and are sufficient to mediate CPE binding, in this study we evaluated the in vitro and in vivo bioactivity of the carboxy-terminal fragment of CPE (i.e., CPE_290-319 binding peptide) as a carrier for tumor imaging agents and intracellular delivery of therapeutic drugs. Claudin-3 and -4 expression was examined with rt-PCR and flow cytometry in multiple primary ovarian carcinoma cell lines. Cell binding assays were used to assess the accuracy and specificity of the CPE peptide in vitro against primary chemotherapy-resistant ovarian carcinoma cell lines. Confocal microscopy and biodistribution assays were performed to evaluate the localization and uptake of the FITC-conjugated CPE peptide in established tumor tissue.

Results

Using a FITC-conjugated CPE peptide we show specific in vitro and in vivo binding to multiple primary chemotherapy resistant ovarian cancer cell lines. Bio-distribution studies in SCID mice harboring clinically relevant animal models of chemotherapy resistant ovarian carcinoma showed higher uptake of the peptide in tumor cells than in normal organs. Imunofluorescence was detectable within discrete accumulations (i.e., tumor spheroids) or even single chemotherapy resistant ovarian cancer cells floating in the ascites of xenografted animals while a time-dependent internalization of the FITC-conjugated CPE peptide was consistently noted in chemotherapy-resistant ovarian tumor cells by confocal microscopy.

Conclusions

Based on the high levels of claudin-3 and -4 expression in chemotherapy-resistant ovarian cancer and other highly aggressive human epithelial tumors including breast, prostate and pancreatic cancers, CPE peptide holds promise as a lead peptide for the development of new diagnostic tracers or alternative anticancer agents.

Spin-Peierls transition in low-dimensional quantum spin systems: a Green's function approach

We study the spin-Peierls (SP) transition of one-dimensional chain polymeric complexes coupled to lattice by means of many-body Green's function theory. The chain effective elastic constant is an intrinsic factor that determines the order of SP transition. It is found that the SP transition temperature T(SP) and the susceptibility-maximum temperature T(max) are in agreement with the experimental results. When an external magnetic field is applied to the chain, it makes T(SP) and T(max) decrease, and drives the SP transition from the second order to the first order. Besides, we show that the two-site thermal entanglement entropy is a good indicator of SP transition. Further considering the effect of interchain coupling on SP transition, with weak coupling of double-chain, the theoretical values are closer to the experimental results. We also calculate the density of states and spectral functions, which show that the energy gap vanishes at a critical temperature lower than T(SP), indicating a gapless SP phase lies in the gapped dimerized phase. The interchain coupling can drive the SP transition from the second order to the first order, while the SP dimerization may collapse for large interchain couplings.

Abstract 2029: Identification and characterization of cancer stem cells in ovarian cancer

Introduction: One of the major burdens in the treatment of epithelial ovarian cancer (EOC) is the high percentage of recurrence characterized by chemoresistance. The biology underlying the tumor’s high capacity for recurrence has not been elucidated. Tumors are made of a heterogeneous cell population consisting of both cancer and non-cancer cells. New data suggest that even the cancer cell population is heterogeneous and contains a small subset of cells, the cancer stem cells (CSC), which constitute a reservoir that can self-renew and therefore maintain the tumor. CSC can divide and expand their pool and also differentiate into non-CSC, which constitute the bulk of the tumor. Contrary to CSC, the non-CSC are rapidly dividing and therefore sensitive to therapies, which target highly proliferative cells. In the present study we identified and characterized the CSC of EOC.

Methods: EOC cells were isolated from malignant ovarian cancer ascities and solid tumors (n=80). Marker expression was determined using Flow Cytometry, Western Blots and Immunocytochemistry. Xenograft nude mice model was used for tumor growth by injecting cancer cells either s.c. or i.p. Isolation of CD44+ population was done using FACS. Cancer cells were maintained in culture as previously described {Kamsteeg, 2003 #358}

Results: CSC were identified in EOC cells isolated form ascites and solid tumors with the following characteristics: 1) cellular markers: CD44+, MyD88+, constitutive NFκB activity and cytokine and chemokine production, high capacity for repair, chemoresistance to conventional chemotherapies, resistance to TNFα-mediated apoptosis, capacity to form spheroids in suspension, and unique microRNA phenotype; 2) tumor formation in animals: 100% CD44+ cells formed tumors which contained 10% CD44+ and 90% CD44-negative cells. Re-injection of isolated CD44+ cells from previous engraftment was able to again recapitulate the original tumor phenotype. Isolation and in vitro treatment of CD44+ cells from fresh samples showed resistance to carboplatin and paclitaxel. In contrast, the sorted CD44-negative cell population from the same sample/patient was chemosensitive.

Conclusion: Present chemotherapy modalities eliminate the bulk of the tumor but it leaves a core of cancer cells with high capacity for repair and renewal. CSC corresponds to the core of malignant cells that promotes recurrence and chemoresistance. Identification of these cells represents the first step in the development of therapeutic modalities that can eliminate not only the bulk of the tumor but its source. Prevention of recurrence will be achieved only with therapies targeting this cell population.

Suppression of proline-directed protein kinase F(A) potentiates apoptotic induction and greatly enhances chemosensitivity in human acute lymphoblastic leukemia cells

BACKGROUND

Previously, the authors reported that specific antisense suppression of overexpressed proline-directed protein kinase (PDPK) F(A) enhances the chemosensitivity of various clinical anticancer drugs up to > 100-fold in human prostate carcinoma cells, suggesting an association of PDPK F(A) with drug resistance in human malignancies.

METHODS

In this report, by using a similar approach, the authors demonstrate further that the suppression of PDPK F(A) enhances even more dramatically the chemosensitivity of clinically used anticancer drugs in various types of human acute lymphoblastic leukemia (ALL) cells.

RESULTS

Compared with parental and control transfected cells, transduced ALL cells (both Jurkat and CCRF-CEM cells) with low levels of PDPK F(A) displayed an enhanced sensitivity to vincristine, vinblastine, paclitaxel, methotrexate, doxorubicin, and daunorubicin. Estimation of the 50% inhibitory concentration (IC(50)) index further revealed that the transduced cells displayed up to > 3000-fold drug sensitivity, and there was a correlation between suppressed levels of PDPK F(A) and drug sensitivity. A mechanistic study further revealed that the enhanced chemosensitivity in transduced ALL cells was due mainly to the potentiation of apoptotic induction.

CONCLUSIONS

Taken together, the results demonstrate that the suppression of overexpressed PDPK F(A) greatly enhances the chemosensitivity of various clinical anticancer drugs in both types of human ALL cells, providing initial evidence for an important role of this PDPK in controlling multidrug resistance of ALL.

Molecular characterization of a tyrosine-specific protein phosphatase encoded by a stress-responsive gene in Arabidopsis

Protein tyrosine kinases and phosphatases play a vital role in the regulation of cell growth and differentiation in animal systems. However, none of these enzymes has been characterized from higher plants. In this study, we isolated a cDNA encoding a putative protein tyrosine phosphatase (PTPase) from Arabidopsis (referred to as AtPTP1). The expression level of AtPTP1 is highly sensitive to environmental stresses. High-salt conditions increased AtPTP1 mRNA levels, whereas cold treatment rapidly eliminated the AtPTP1 transcript. The recombinant AtPTP1 protein specifically hydrolyzed phosphotyrosine, but not phosphoserine/threonine, in protein substrates. Site-directed mutagenesis defined two highly conserved amino acids, cysteine-265 and aspartate-234, as being essential for the phosphatase activity of the AtPTP1 protein, suggesting a common catalytic mechanism for PTPases from all eukaryotic systems. In summary, we have identified AtPTP1 as a tyrosine-specific protein phosphatase that may function in stress responses of higher plants.

AtKuP1: a dual-affinity K+ transporter from Arabidopsis

Plant roots contain both high- and low-affinity transport systems for uptake of K+ from the soil. In this study, we characterize a K+ transporter that functions in both high- and low-affinity uptake. Using yeast complementation analysis, we isolated a cDNA for a functional K+ transporter from Arabidopsis (referred to as AtKUP1 for Arabidopsis thaliana K+ uptake). When expressed in a yeast mutant, AtKUP1 dramatically increased K+ uptake capacity at both a low and high [K+] range. Kinetic analyses showed that AtKUP1-mediated K+ uptake displays a "biphasic" pattern similar to that observed in plant roots. The transition from the high-affinity phase (K(m) of 44 microM) to the low-affinity phase (K(m) of 11 mM) occurred at 100 to 200 microM external K+. Both low- and high-affinity K+ uptake via AtKUP1 were inhibited by 5 mM or higher concentrations of NaCl. In addition, AtKUP1-mediated K+ uptake was inhibited by K+ channel blockers, including tetraethylammonium, Cs+, and Ba2+. Consistent with a possible function in K+ uptake from the soil, the AtKUP1 gene is primarily expressed in roots. We conclude that the AtKUP1 gene product may function as a K+ transporter in Arabidopsis roots over a broad range of [K+] in the soil.

AtKuP1: a dual-affinity K+ transporter from Arabidopsis

Plant roots contain both high- and low-affinity transport systems for uptake of K+ from the soil. In this study, we characterize a K+ transporter that functions in both high- and low-affinity uptake. Using yeast complementation analysis, we isolated a cDNA for a functional K+ transporter from Arabidopsis (referred to as AtKUP1 for Arabidopsis thaliana K+ uptake). When expressed in a yeast mutant, AtKUP1 dramatically increased K+ uptake capacity at both a low and high [K+] range. Kinetic analyses showed that AtKUP1-mediated K+ uptake displays a "biphasic" pattern similar to that observed in plant roots. The transition from the high-affinity phase (K(m) of 44 microM) to the low-affinity phase (K(m) of 11 mM) occurred at 100 to 200 microM external K+. Both low- and high-affinity K+ uptake via AtKUP1 were inhibited by 5 mM or higher concentrations of NaCl. In addition, AtKUP1-mediated K+ uptake was inhibited by K+ channel blockers, including tetraethylammonium, Cs+, and Ba2+. Consistent with a possible function in K+ uptake from the soil, the AtKUP1 gene is primarily expressed in roots. We conclude that the AtKUP1 gene product may function as a K+ transporter in Arabidopsis roots over a broad range of [K+] in the soil.