Antiproliferative activity and electrochemical oxygen evolution by Ni(II) complexes of N'-(aroyl)-hydrazine carbodithioates.

The electrochemical water splitting by transition metal complexes is emerging very rapidly. The nickel complexes also play a very vital role in various biological activities. Here, three new ligands {H2mbhce = N'-(4-methyl-benzoyl), H2pchce = N'-(pyridine-carbonyl) and H2hbhce = N'-(2-hydroxy-benzoyl) hydrazine carbodithioic acid ethyl ester} and their corresponding Ni(II) complexes [Ni(Hmbhce)2(py)2] (1), [Ni(pchce)(o-phen)2]·CH3OH·H2O (2) and [Ni(hbhce)(o-phen)2]·1.75CHCl3·H2O (3) have been synthesized and fully characterized by various physicochemical and X-ray crystallography techniques. The photoluminescence study and thermal degradations were also examined. The treatment of K562 cells with the increasing concentrations of the nickel salts, ligands, and complexes 1, 2, and 3 showed dose-dependent cytotoxicity. The cytotoxic activity of ligands reveals that ligand H2mbhce is more potent in inhibiting the growth of tumor cells in comparison to other ligands H2pbhce and H2hbhce. Cytotoxicity assay results indicate that all complexes have remarkable cytotoxic potential in comparison to either nickel salts or the free ligands. Among these complexes, complex 1 has significantly better anti-tumor activity as compared to complexes 2 and 3. The electrochemical study of complexes 1, 2, and 3 for water oxidation reveals that all the complexes possess admirable electrocatalytic activity towards oxygen evolution reaction (OER) and have lower overpotential (328, 338, and 370 mV, respectively) than many previously reported complexes and RuO2 (390 mV). Among complexes 1, 2, and 3, complex-2 shows a better water oxidation response. Consequently, these complexes have great potential to be utilized in fuel cells. The more reliable electrochemical parameter TOF is also calculated for all three complexes.

Plasma DNA level in predicting therapeutic efficacy in advanced nonsmall cell lung cancer.

Assessment of total plasma DNA can be a promising noninvasive tool for monitoring the effect of cytotoxic therapies in order to predict therapeutic efficacy at an early stage. Cell-free plasma DNA levels were quantified before the first, second and third cycle of chemotherapy in 42 patients with advanced nonsmall cell lung cancer and correlated with response to therapy, as assessed by computed tomography following the third chemotherapy cycle. A significantly lower plasma DNA level, measured before various treatment cycles, was found in patients with remission or stable disease than in those with progression. Higher levels and insufficient decrease in plasma DNA levels during the course of chemotherapy indicated poor outcome. For predicting insufficient therapy response, a sensitivity of 26.9% was achieved at 100% specificity using plasma DNA levels before the first therapy cycle. Prediction of disease progression was achieved with a sensitivity of 35.7% at 100% specificity using plasma DNA levels before the first therapy cycle. Monitoring of plasma DNA levels during the course of chemotherapy could identify patients who are likely to exhibit an insufficient therapeutic response and disease progression at an early stage. This may help in individualising treatment, and could lead to better management of advanced-stage lung cancer.

Overexpression of STAT3 in HPV-mediated cervical cancer in a north Indian population.

The constitutively activated STAT family members, particularly STAT3, have been shown to possess transforming properties, and are strongly correlated with tumor development and progression. STAT3 transmits signals from many cytokines and growth factors to target genes in the nucleus through the Jak/Stat signaling pathway. HPV is the main etiological factor in the development of cervical cancer. In the current study, the expression of STAT3 was analyzed in various stages of HPV-mediated cervical carcinogenesis. Tissue biopsies from 100 patients with cervical cancer of different stages and normal tissues from patients undergoing hysterectomy were selected for studying the HPV status and STAT3 expression. HPV status of each corresponding biopsy was analyzed by PCR and typing. The mRNA expression was analyzed by reverse-transcriptase polymerase chain reaction (RT-PCR). HPV infection was detected in majority of cases: 75% (9/12) in precancer, 85% (34/40) stage I & II, and 95% (36/38) in stage III & IV of cervical cancer cases by L1 PCR. Further sub typing revealed HPV16 in 100% (9/9) of L1 positives in precancerous & 90% (63/70) in different stages of cancer. Significant level of STAT3 mRNA expression was predominantly found in cervical cancer cases as compared to normal controls (P = 0.001). We also found a significant correlation of STAT3 expression in cases infected with HPV (P = 0.001). Our results indicate a potentially interactive effect between HPV 16/18 and transcriptional activation of STAT3 gene in cervical carcinogenesis. To our knowledge, this is the first such study to be reported from India. Further investigations are needed to determine the influence of STAT3 expression on cervical carcinogenesis and its possible interaction with HPV infection status.

MUC1 oncoprotein is targeted to mitochondria by heregulin-induced activation of c-Src and the molecular chaperone HSP90.

The MUC1 heterodimeric transmembrane glycoprotein is aberrantly overexpressed by most human carcinomas. The MUC1 C-terminal subunit localizes to mitochondria and blocks stress-induced activation of the intrinsic apoptotic pathway. How MUC1 is delivered to mitochondria is not known. The present studies demonstrate that MUC1 forms intracellular complexes with HSP70 and HSP90. We show that the MUC1 cytoplasmic domain binds directly to HSP70 in vitro. By contrast, binding of MUC1 to HSP90 in vitro is induced by c-Src-mediated phosphorylation of the MUC1 cytoplasmic domain. c-Src also increases binding of MUC1 to HSP90 in cells. In concert with these results, we show that heregulin (HRG), a ligand for ErbB receptors, activates c-Src and, in turn, stimulates binding of MUC1 to HSP90. We also show that inhibitors of c-Src or HSP90 block HRG-induced targeting of MUC1 to mitochondria and integration of MUC1 into the mitochondrial outer membrane. These findings indicate that MUC1 is delivered to mitochondria by a mechanism involving activation of the ErbB receptor-->c-Src pathway and transport by the molecular chaperone HSP70/HSP90 complex.

Interaction of glycogen synthase kinase 3beta with the DF3/MUC1 carcinoma-associated antigen and beta-catenin.

The DF3/MUC1 mucin-like glycoprotein is highly overexpressed in human carcinomas. Recent studies have demonstrated that the cytoplasmic domain of MUC1 interacts with beta-catenin. Here we show that MUC1 associates with glycogen synthase kinase 3beta (GSK3beta). GSK3beta binds directly to an STDRSPYE site in MUC1 and phosphorylates the serine adjacent to proline. Phosphorylation of MUC1 by GSK3beta decreases binding of MUC1 to beta-catenin in vitro and in vivo. GSK3beta-mediated phosphorylation of MUC1 had no apparent effect on beta-catenin levels or the transcriptional coactivation function of beta-catenin. The results, however, demonstrate that MUC1 expression decreases binding of beta-catenin to the E-cadherin cell adhesion molecule. Negative regulation of the beta-catenin-MUC1 interaction by GSK3beta is associated with restoration of the complex between beta-catenin and E-cadherin. These findings indicate that GSK3beta decreases the interaction of MUC1 with beta-catenin and that overexpression of MUC1 in the absence of GSK3beta activity inhibits formation of the E-cadherin-beta-catenin complex.

Activation of MEK kinase 1 by the c-Abl protein tyrosine kinase in response to DNA damage.

The c-Abl protein tyrosine kinase is activated by certain DNA-damaging agents and regulates induction of the stress-activated c-Jun N-terminal protein kinase (SAPK). Here we show that nuclear c-Abl associates with MEK kinase 1 (MEKK-1), an upstream effector of the SEK1-->SAPK pathway, in the response of cells to genotoxic stress. The results demonstrate that the nuclear c-Abl binds to MEKK-1 and that c-Abl phosphorylates MEKK-1 in vitro and in vivo. Transient-transfection studies with wild-type and kinase-inactive c-Abl demonstrate c-Abl kinase-dependent activation of MEKK-1. Moreover, c-Abl activates MEKK-1 in vitro and in response to DNA damage. The results also demonstrate that c-Abl induces MEKK-1-mediated phosphorylation and activation of SEK1-SAPK in coupled kinase assays. These findings indicate that c-Abl functions upstream of MEKK-1-dependent activation of SAPK in the response to genotoxic stress.

Inactivation of DNA-dependent protein kinase by protein kinase Cdelta: implications for apoptosis.

Protein kinase Cdelta (PKCdelta) is proteolytically cleaved and activated at the onset of apoptosis induced by DNA-damaging agents, tumor necrosis factor, and anti-Fas antibody. A role for PKCdelta in apoptosis is supported by the finding that overexpression of the catalytic fragment of PKCdelta (PKCdelta CF) in cells is associated with the appearance of certain characteristics of apoptosis. However, the functional relationship between PKCdelta cleavage and induction of apoptosis is unknown. The present studies demonstrate that PKCdelta associates constitutively with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs). The results show that PKCdelta CF phosphorylates DNA-PKcs in vitro. Interaction of DNA-PKcs with PKCdelta CF inhibits the function of DNA-PKcs to form complexes with DNA and to phosphorylate its downstream target, p53. The results also demonstrate that cells deficient in DNA-PK are resistant to apoptosis induced by overexpressing PKCdelta CF. These findings support the hypothesis that functional interactions between PKCdelta and DNA-PK contribute to DNA damage-induced apoptosis.

Latent toxoplasmosis is associated with neurocognitive impairment in young adults with and without chronic HIV infection.

We evaluated the impact of latent toxoplasmosis (LT) on neurocognitive (NC) and neurobehavioural functioning in young adults with and without chronic HIV infection, using a standardised NC test battery, self-reported Beck Depression Inventory, Frontal System Behavior Scale, MINI-International Neuropsychiatric Interview and risk-assessment battery. 194 young adults (median age 24years, 48.2% males) with chronic HIV infection (HIV+) since childhood and 51 HIV seronegative (HIV-) participants were included. HIV+ individuals had good current immunological status (median CD4: 479 cells/µl) despite a low CD4 nadir (median: 93 cells/µl). LT (positive anti-Toxoplasma IgG antibodies) was present in one third of participants. The impairment rates in the HIV- with and without Toxo were not significantly different (p=0.17). However, we observed an increasing trend (p<0.001) in impairment rates with HIV and LT status: HIV-/LT- (6.1%); HIV-/LT+ (22%), HIV+/LT- (31%), HIV+/LT+ (49%). In a multivariable analysis using the entire study group there were main effects on cognition for HIV and also for LT. Within the HIV+ group LT was associated with worse performance globally (p=0.006), in memory (p=0.009), speed of information processing (p=0.01), verbal (p=0.02) and learning (p=0.02) domains. LT was not associated with depressive symptoms, frontal systems dysfunction or risk behaviors in any of the groups. HIV participants with lower Toxoplasma antibody concentration had worse NC performance, with higher GDS values (p=0.03) and worse learning (p=0.002), memory (p=0.006), speed of information processing (p=0.01) T scores. Latent Toxoplasmosis may contribute to NC impairment in young adults, including those with and without chronic HIV infection.

Hsp27 functions as a negative regulator of cytochrome c-dependent activation of procaspase-3.

The release of mitochondrial cytochrome c by genotoxic stress induces the formation of a cytosolic complex with Apaf-1 (mammalian CED4 homolog) and thereby the activation of procaspase-3 (cas-3) and procaspase-9 (cas-9). Here we demonstrate that heat-shock protein 27 (Hsp27) inhibits cytochrome c (cyt c)-dependent activation of cas-3. Hsp27 had no effect on cyt c release, Apaf-1 and cas-9 activation. By contrast, our results show that Hsp27 associates with cas-3, but not Apaf-1 or cas-9, and inhibits activation of cas-3 by cas-9-mediated proteolysis. Furthermore, the present results demonstrate that immunodepletion of Hsp27 depletes cas-3. Importantly, treatment of cells with DNA damaging agents dissociates the Hsp27/cas-3 complex and relieves inhibition of cas-3 activation. These findings define a novel function for Hsp27 and provide the first evidence that a heat shock protein represses cas-3 activation.

A phase I and pharmacokinetic study of a new camptothecin derivative, 9-aminocamptothecin.

Camptothecins are the only available antitumor agents which target the nuclear enzyme topoisomerase I. 9-Aminocamptothecin (9-AC) is a water-insoluble derivative of camptothecin which has demonstrated impressive antitumor activity in preclinical models. While two other water-soluble derivatives, CPT-11 and topotecan, have successfully completed Phase I and Phase II testing, biochemical and tissue culture studies suggest that camptothecin analogues differ in characteristics which may be important in determining antitumor activity. We performed a Phase I trial of 9-AC to determine the pharmacokinetics, dose-limiting toxicity, and maximum tolerated dose of this agent when administered as a 72-h continuous i.v. infusion. Thirty-one patients with resistant solid cancers received 5-60 microgram/m2/h 9-AC for 72 h, repeated at 3-week intervals. The drug was administered in a vehicle containing dimethylacetamide, polyethylene glycol, and phosphoric acid. Blood samples were collected and the lactone (closed ring) form of 9-AC was quantitated. The maximum tolerated dose of 9-AC was determined to be 45 microgram/m2/h. Dose-limiting toxicity consisted of neutropenia. Thrombocytopenia was also prominent. There were no significant nonhematological toxicities. Minimal responses were seen in patients with gastric, colon, and non-small cell lung cancer. Although significant interpatient variation in plasma 9-AC lactone levels was observed, pooled data were fit to a two-compartment model, with a terminal half-life of 36 h. Analyses of topoisomerase protein levels in peripheral blood cells indicated decreases in topoisomerase I accompanied by increases in topoisomerase II in two of three patients. 9-AC is an active antitumor agent and may be administered safely as a 72-h infusion in patients with cancer. Although Phase II trials with a 72-h infusion of 9-AC are warranted, alternate schedules should be evaluated given the dramatic preclinical activity seen with more prolonged administrations.

Induction of apoptosis in bone marrow cells by gangliosides produced by a T cell lymphoma.

The present study was conducted to investigate the mode of cell death of bone marrow cells (BMC) treated in vivo or in vitro with gangliosides (DLG) derived from a T cell lymphoma, designated as Dalton's lymphoma (DL). BMC undergoing cell death showed morphological features characteristic to apoptosis such as cell shrinkage, plasma membrane blebbing and densely stained chromatin. DLG-induced apoptosis was further confirmed by analysis of DNA from DLG-treated BMC by flow cytometry and agarose gel electrophoresis which showed an increase in hypodiploid DNA and internucleosomal DNA cleavage, respectively. Immunoblotting of p53 and Bax demonstrated an increase in the levels of p53 and Bax proteins. BMC treated with DLG also showed translocation of NF-kappaB protein into the nucleus. Antibodies to ganglioside G(D3), a constituent of DLG, neutralized the effect of DLG. Further, supplementation of DLG-containing BMC cultures with granulocyte macrophage-colony stimulating factor (GM-CSF) or macrophage-colony stimulating factor (M-CSF) prevented the apoptosis-inducing action of DLG.

Involvement of amino acids 361 to 364 of human topoisomerase I in camptothecin resistance and enzyme catalysis.

Camptothecins are antineoplastic drugs that specifically target the enzyme DNA topoisomerase I. Prior work has identified a human topoisomerase I mutation, F361S, that confers resistance to camptothecin. We now demonstrate that substitutions in the 361-364 region can alter DNA cleavage/ligation by the enzyme. The defective catalysis exhibited by certain mutants likely relates to an impaired interaction with DNA, since these enzymes are more sensitive to the inhibitory effects of DNA binding ligands. Moreover, studies with peptides and fusion proteins suggest that the 361-364 region may bind DNA directly. The finding that the 361-364 region is involved in both enzyme catalysis and camptothecin resistance suggests that this region is part of the active site of human topoisomerase I and that camptothecin may interact with the enzyme at this site.

Gangliosides derived from a T cell lymphoma inhibit bone marrow cell proliferation and differentiation.

Previously, we have observed a modulation in the bone marrow hematopoiesis and alteration in the repertoire of blood monocytes and lymphocytes in mice bearing a spontaneous T cell lymphoma, designated as Dalton's lymphoma (DL). In the present investigation, we show that in vivo or in vitro treatment of bone marrow cells (BMC) with gangliosides of DL (DLG) results in inhibition of proliferative ability and alteration of colony-forming ability (CFA) of BMC. BMC incubated with DLG also showed a decrease in cell viability in a concentration-dependent manner. BMC colony-forming assays in the presence of macrophage-colony-stimulating factor (M-CSF) showed a dose-dependent decrease in the number of colonies with a concomitant decrease in macrophage- and granulocyte macrophage-colony-forming units (CFU-M and CFU-GM, respectively) and an increase in granulocyte-CFU (CFU-G). Neuraminidase treatment of DLG abrogated their inhibitory action on BMC. Further, antibodies to GD3 and to lesser extent GM2 neutralized the inhibitory effect of DLG on BMC.

Mutants of Arabidopsis as tools to understand the regulation of phenylpropanoid pathway and UVB protection mechanisms.

Plants accumulate certain phenylpropanoid compounds in the vacuoles of their epidermal and subepidermal cell layers thereby protecting the underlying tissue against UVB-induced damage. However, a number of mutants of Arabidopsis thaliana are known that fail to synthesize these protective pigments, thereby allowing harmful UVB radiation to penetrate into their dermal layers. Study of several of these nonlethal mutants, defective in various aspects of flavonoid and lignin biosynthesis, has led to a better understanding of the coordinate regulation and expression of important genes as well as of mechanisms involved in plant defense against UVB radiation. The characteristics of the various phenylpropanoid mutants of Arabidopsis, viz. flavonoid mutants (banyuls [ban]; increased chalcone synthase expression 1 [icx1]; transparent testa [tt] and ultraviolet sensitive [uvs]) and hydroxycinnamic acid ester mutants (ferulic acid hydroxylase 1 [fah1] and sinapoylglucose accumulator 1 [sng1]) are discussed in detail. We have briefly touched upon, wherever relevant, the unique aspects in other plant species too.

Short term treatment of tamoxifen and estradiol on estradiol and progesterone receptors in rabbit uterus.

Effects of tamoxifen (Tam) on cytosolic estradiol (E2) receptors (ERc), progesterone (P4) receptors (PRc), nuclear estradiol (ERn) and progesterone receptors (PRn) were studied in adult normal rabbit uterine tissue. The ratio of cytosol: nuclear estradiol receptors (ER) was greater in rabbits treated with Tam than E2 or control uterine tissues. Rabbit uterine progesterone receptors (PR) in E2 treated animal were greater than Tam-treated animals. Tam caused nuclear accumulation of estradiol receptor, and simultaneous administration of E2 + Tam 500, estradiol could not revert Tam mediated accumulation of ER. The results suggest that Tam has an essentially antagonist action in the rabbit uterine tissue.

Comparison of vestibular evoked myogenic potentials elicited by click and short duration tone burst stimuli.

INTRODUCTION: Vestibular evoked myogenic potentials are short latency electrical impulses that are produced in response to higher level acoustic stimuli. They are used clinically to diagnose sacculocollic pathway dysfunction. AIM: This study aimed to compare the vestibular evoked myogenic potential responses elicited by click stimuli and short duration tone burst stimuli, in normal hearing individuals. METHOD: Seventeen subjects participated. In all subjects, we assessed vestibular evoked myogenic potentials elicited by click and short duration tone burst stimuli. RESULTS AND CONCLUSION: The latency of the vestibular evoked myogenic potential responses (i.e. the p13 and n23 peaks) was longer for tone burst stimuli compared with click stimuli. The amplitude of the p13-n23 waveform was greater for tone burst stimuli than click stimuli. Thus, the click stimulus may be preferable for clinical assessment and identification of abnormalities as this stimulus has less variability, while a low frequency tone burst stimulus may be preferable when assessing the presence or absence of vestibular evoked myogenic potential responses.

Efficacy of "Dimodent" sex predictive equation assessed in an Indian population.

Teeth are considered as a useful adjunct for sex assessment and may play an important role in constructing a post-mortem profile. The Dimodent method is based on the high degree of sex discrimination obtained with the mandibular canine and the high correlation coefficients between mandibular canine and lateral incisor mesiodistal (MD) and buccolingual (BL) dimensions. This has been evaluated in the French and Lebanese, but no study exists on its efficacy in Indians. Here, we have applied the 'Dimodent' equation on an Indian sample (100 males, 100 females; age range of 19-27yrs). Additionally, a population-specific Dimodent equation was derived using logistic regression analysis and applied to our sample. Also, the sex determination potential of MD and BL measurements of mandibular lateral incisors and canines, individually, was assessed. We found a poor sex assessment accuracy using the Dimodent equation of Fronty (34.5%) in our Indian sample, but the populationspecific Dimodent equation gave a better accuracy (72%).Thus, it appears that sexual dimorphism in teeth is population-specific; consequently the Dimodent equation has to be derived individually in different populations for use in sex assessment. The mesiodistal measurement of the mandibular canine alone gave a marginally higher accuracy (72.5%); therefore, we suggest the use of mandibular canines alone rather than the Dimodent method.

Aberrant promoter methylation and loss of suppressor of cytokine signalling-1 gene expression in the development of uterine cervical carcinogenesis.

BACKGROUND: Cervical cancer is a leading cause of cancer related deaths in women worldwide caused due to infection of high-risk human papillomaviruses. As JAK/STAT signalling pathway has been shown to play an important role during carcinogenesis, we studied the role of silencing of Suppressor of Cytokine Signalling-1 (SOCS-1) gene, a negative regulator of JAK/STAT pathway in cervical cancer. METHODS: The expression pattern of SOCS-1 mRNA and protein was analyzed in different stages of cervical tumor biopsies while normal cervical tissues served as controls. RT-PCR, immunohistochemistry and methylation-specific PCR (MSP) were performed to assess the expression pattern and promoter methylation of SOCS-1 gene in a total of 120 fresh surgically resected cervical tissue specimens comprising precancer (n = 12), cancer (n = 78) and normal controls (n = 30). RESULTS: Compared with expression of SOCS-1 in normal tissues, 64% of the tumor tissues expressed either undetectable or reduced expression. Aberrant promoter methylation of SOCS-1 was found in 61% of the cervical tumor tissues. SOCS-1 expression and methylation were significantly associated with severity of the disease (p < 0.01). CONCLUSION: We demonstrate for the first time the transcriptional inactivation of SOCS-1 gene due to hypermethylation and synergism with HPV infection which may play an important role in cervical carcinoma.