Advanced oxidation protein products as a biomarker of cutaneous lupus erythematosus complicated by nephritis: a case-control study

Oxidative stress is involved in the pathogenesis of lupus nephritis (LN). The current study investigated the significance of advanced oxidation protein products (AOPPs) as a biomarker of LN in patients with cutaneous lupus erythematosus. Ninety-two patients who initially presented with systemic lupus erythematosus were divided into the LN- and LN+ groups. Serum AOPP levels were determined, and the association between AOPP levels and LN was investigated in a case-control study. In the LN+ group, patients with higher AOPP levels exhibited higher levels of dsDNA and proteinuria but lower levels of eGFR and complement C3 compared to those in patients with lower AOPP levels. A multivariable logistic regression model showed that the AOPP level was an independent risk factor for LN. The risk of nephritis specifically increased 24% for each 10 μM increase in AOPP (95% confidence interval, 1.166-1.915, P = 0.030). In contrast, neither elevated dsDNA level nor decreased complement C3 level was an independent risk factor for LN. Higher serum AOPP levels were associated with an increased risk of LN. Therefore, future studies are warranted to determine the potential clinical value of this novel biomarker.

Novel Peptidomimetics for Inhibition of HER2:HER3 Heterodimerization in HER2-Positive Breast Cancer

The current approach to treating HER2-overexpressed breast cancer is the use of monoclonal antibodies or a combination of antibodies with traditional chemotherapeutic agents or kinase inhibitors. Our approach is to target clinically validated HER2 domain IV with peptidomimetics and inhibit the protein-protein interactions (PPI) of HERs. Unlike antibodies, peptidomimetics have advantages in terms of stability, modification, and molecular size. We have designed peptidomimetics (compounds 5 and 9) that bind to HER2 domain IV, inhibit protein-protein interactions, and decrease cell viability in breast cancer cells with HER2 overexpression. We have shown, using enzyme fragment complementation and proximity ligation assays, that peptidomimetics inhibit the PPI of HER2:HER3. Compounds 5 and 9 suppressed the tumor growth in a xenograft mouse model. Furthermore, we have shown that these compounds inhibit PPI of HER2:HER3 and phosphorylation of HER2 as compared to control in tissue samples derived from in vivo studies. The stability of the compounds was also investigated in mouse serum, and the compounds exhibited stability with a half-life of up to 3 h. These results suggest that the novel peptidomimetics we have developed target the extracellular domain of HER2 protein and inhibit HER2:HER3 interaction, providing a novel method to treat HER2-positive cancer.

Biological activities of fusarochromanone: a potent anti-cancer agent

Background

Fusarochromanone (FC101) is a small molecule fungal metabolite with a host of interesting biological functions, including very potent anti-angiogenic and direct anti-cancer activity.

Results

Herein, we report that FC101 exhibits very potent in-vitro growth inhibitory effects (IC₅₀ ranging from 10nM-2.5 μM) against HaCat (pre-malignant skin), P9-WT (malignant skin), MCF-7 (low malignant breast), MDA-231 (malignant breast), SV-HUC (premalignant bladder), UM-UC14 (malignant bladder), and PC3 (malignant prostate) in a time-course and dose-dependent manner, with the UM-UC14 cells being the most sensitive. FC101 induces apoptosis and an increase in proportion of cells in the sub-G1 phase in both HaCat and P9-WT cell lines as evidenced by cell cycle profile analysis. In a mouse xenograft SCC tumor model, FC101 was well tolerated, non-toxic, and achieved a 30% reduction in tumor size at a dose of 8 mg/kg/day. FC101 is also a potent anti-angiogenenic agent. At nanomolar doses, FC101 inhibits the vascular endothelial growth factor-A (VEGF-A)-mediated proliferation of endothelial cells.

Conclusions

Our data presented here indicates that FC101 is an excellent lead candidate for a small molecule anti-cancer agent that simultaneously affects angiogenesis signaling, cancer signal transduction, and apoptosis. Further understanding of the underlying FC101’s molecular mechanism may lead to the design of novel targeted and selective therapeutics, both of which are pursued targets in cancer drug discovery.

Meta-analysis on the efficacy and tolerability of the augmentation of antidepressants with atypical antipsychotics in patients with major depressive disorder

We assessed the efficacy and tolerability of the augmentation of antidepressants (ATDs) with atypical antipsychotics (AAPs) to treat patients with major depressive disorder. A retrograde study to identify relevant patient data included databases of PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and Database of Abstracts of Reviews of Effects. Data from 17 trials, involving 3807 participants, were identified. The remission rate (RR) and overall response rate (ORR) of adjunctive treatment with AAPs were significantly higher than placebo treatment: RR=1.90 (95%CI=1.61-2.23, z=7.74, P<0.00001) and ORR=1.68 (95%CI=1.45-1.94, z=7.07, P<0.00001). We found that the short-term (4 weeks) treatment [ORR=1.70 (95%CI=0.98-2.95, Z=1.89, P=0.06)] was significantly different from the long-term (6-12 weeks) treatment [ORR=1.68 (95%CI=1.45-1.94, z=7.07, P<0.00001)]. No significant difference in ORR was observed between groups with or without sedative drugs. The discontinuation rate due to adverse effects was higher for adjunctive treatment with AAPs: ORR=3.32 (95%CI=2.35-4.70, z=6.78, P<0.00001). These results demonstrate that the augmentation of ATDs with AAPs (olanzapine, quetiapine, aripiprazole, and risperidone) was more effective than a placebo in improving response and remission rates, although associated with a higher discontinuation rate due to adverse effects.

Effect of CDH1 gene methylation on transforming growth factor (TGF-β)-induced epithelial-mesenchymal transition in alveolar epithelial cell line A549

The aim of this study was to investigate the specific molecular mechanism of the transforming growth factor β (TGF-β)-induced epithelial-mesenchymal transition in a lung cancer cell line, and to provide new ideas for targeting therapy of lung cancer. A549 cells were treated with different concentrations of TGF-β and 5-aza-deoxycytidine (5-aza-dC). The morphological changes after the intervention were observed. The change in the expression of the epithelial marker E-cadherin (E-cad) was detected by Western blot. The proliferation of A549 cells was measured using the MTT assay. Cell movement and invasion capacity was evaluated with the cell scratch test and invasion test. TGF-β induced A549 cells to transform to a mesenchymal cell morphology and downregulated the expression of E-cad, and 5-aza-dC inhibited this phenomenon. Compared with the control group, the number of transmembrane cells was higher and cell migration was markedly increased in the experimental group with continued culture in the presence of 10 ng/mL TGF-β, showing significant differences (P < 0.05). CDH1 gene methylation is involved in TGF-β-induced epithelial-mesenchymal transition in the alveolar epithelial cell line A549.

3-Ketone-4,6-diene ceramide analogs exclusively induce apoptosis in chemo-resistant cancer cells

Multidrug-resistance is a major cause of cancer chemotherapy failure in clinical treatment. Evidence shows that multidrug-resistant cancer cells are as sensitive as corresponding regular cancer cells under the exposure to anticancer ceramide analogs. In this work we designed five new ceramide analogs with different backbones, in order to test the hypothesis that extending the conjugated system in ceramide analogs would lead to an increase of their anticancer activity and selectivity towards resistant cancer cells. The analogs with the 3-ketone-4,6-diene backbone show the highest apoptosis-inducing efficacy. The most potent compound, analog 406, possesses higher pro-apoptotic activity in chemo-resistant cell lines MCF-7TN-R and NCI/ADR-RES than the corresponding chemo-sensitive cell lines MCF-7 and OVCAR-8, respectively. However, this compound shows the same potency in inhibiting the growth of another pair of chemo-sensitive and chemo-resistant cancer cells, MCF-7 and MCF-7/Dox. Mechanism investigations indicate that analog 406 can induce apoptosis in chemo-resistant cancer cells through the mitochondrial pathway. Cellular glucosylceramide synthase assay shows that analog 406 does not interrupt glucosylceramide synthase in chemo-resistant cancer cell NCI/ADR-RES. These findings suggest that due to certain intrinsic properties, ceramide analogs' pro-apoptotic activity is not disrupted by the normal drug-resistance mechanisms, leading to their potential use for overcoming cancer multidrug-resistance.

Enhanced tumor accumulation and cellular uptake of liposomes modified with ether-bond linked cholesterol derivatives

Novel liposomal formulations based on cholesterol modification had been designed previously by our lab, but we found them with a poor stability and short half-life, especially in blood circulation. The results might be attributed to the hydrolysis of ester linked cholesterol derivatives by esterase in plasma. Thus, in this study, we newly synthesized ether-linked cholesterol derivatives and compared them to other preparations. A comparison with the substrate cholesterol-PEG2000-maleimide showed that ether-linked cholesterol-PEG2000-maleimide could relatively maintain integrity in serum, with only a small mottle emerging on TLC (thin-layer chromatography) plates through the experiment. Then a cell-penetrating peptide TAT was attached to the distal end of CHO-PEG2000 to prepare liposomes and to further evaluate the two cholesterol derivatives. Optimized liposomes (65:35, lipid/cholesterol, molar ratio) composed of 3% CHO-PEG2000 and 3% CHO-PEG2000-TAT showed good stability in 50%FBS (fetal bovine serum). In vitro experiments showed that as incubation time prolonged, ether-linked-TAT LIP showed a 3.67-fold higher uptake amount than ester-linked-TAT LIP. In vivo, ether-linked-TAT LIP accumulated better in tumors and had a 40% higher cellular uptake amount. Altogether, we could conclude that our newly ether-linked cholesterol derivatives possessed better stability especially in blood circulation which led to increased tumor cellular uptake in vitro and in vivo. Our study may offer a better way in cholesterol modification to prepare functionalized liposomes.

Ceramide glycosylation catalyzed by glucosylceramide synthase and cancer drug resistance

Glucosylceramide synthase (GCS), converting ceramide to glucosylceramide, catalyzes the first reaction of ceramide glycosylation in sphingolipid metabolism. This glycosylation by GCS is a critical step regulating the modulation of cellular activities by controlling ceramide and glycosphingolipids (GSLs). An increase of ceramide in response to stresses, such as chemotherapy, drives cells to proliferation arrest and apoptosis or autophagy; however, ceramide glycosylation promptly eliminates ceramide and consequently, these induced processes, thus protecting cancer cells. Further, persistently enhanced ceramide glycosylation can increase GSLs, participating in selecting cancer cells to drug resistance. GCS is overexpressed in diverse drug-resistant cancer cells and in tumors of breast, colon, and leukemia that display poor response to chemotherapy. As ceramide glycosylation by GCS is a rate-limiting step in GSL synthesis, inhibition of GCS sensitizes cancer cells to anticancer drugs and eradicates cancer stem cells. Mechanistic studies indicate that uncoupling ceramide glycosylation can modulate gene expression, decreasing MDR1 through the cSrc/β-catenin pathway and restoring p53 expression via RNA splicing. These studies not only expand our knowledge in understanding how ceramide glycosylation affects cancer cells but also provide novel therapeutic approaches for targeting refractory tumors.

Glucose regulates secretion of exogenously expressed insulin from HepG2 cells in vitro and in a mouse model of diabetes mellitus in vivo

Glucose-controlled insulin secretion is a key component of its regulation. Here, we examined whether liver cell secretion of insulin derived from an engineered construct can be regulated by glucose. Adenovirus constructs were designed to express proinsulin or mature insulin containing the conditional binding domain (CBD). This motif binds GRP78 (HSPA5), an endoplasmic reticulum (ER) protein that enables the chimeric hormone to enter into and stay within the ER until glucose regulates its release from the organelle. Infected HepG2 cells expressed proinsulin mRNA and the protein containing the CBD. Immunocytochemistry studies suggested that GRP78 and proinsulin appeared together in the ER of the cell. The amount of hormone released from infected cells varied directly with the ambient concentration of glucose in the media. Glucose-regulated release of the hormone from infected cells was rapid and sustained. Removal of glucose from the cells decreased release of the hormone. In streptozotocin-induced diabetic mice, when infected with adenovirus expressing mature insulin, glucose levels declined. Our data show that glucose regulates release of exogenously expressed insulin from the ER of liver cells. This approach may be useful in devising new ways to treat diabetes mellitus.

Abstract 3199: Ceramide restores the expression of wild-type p53 tumor suppressor in mRNA splicing through PP1 and ASF/SF2

p53 mutants that have been detected in approximately 50% of tumors loss the activity in stabilizing the genome and tumor suppression, and further exhibit oncogenic function in cancer cells. Most tumors that exhibit disrupted p53 signaling pathways remain addicted to p53 mutants, and p53 mutants have emerged as perhaps the most important target to improve cancer treatment. Most works in restoring p53 activity focus on either altering protein conformations of the mutants or introducing foreign p53 gene into cells. Using gene silencing strategy and mass spectrometry, here we demonstrated that ceramide modulates the RNA splicing to restore the expression of wild-type p53 in p53 deletion-mutant ovarian cancer cells. Enhanced endogenous long-carbon chain ceramide species (C16- to C24-ceramides) and exogenous C6-ceramide, but not other sphingolipids, restored wild-type p53 mRNA (intact exon-5), phosphorylated p53 protein (Ser15 in exon-5) and p53-responsive proteins (p21, Bax) in cells that dominantly expressed a deleted p53-mRNA and protein in exon-5. Thus, the restored p53 sensitized the cells to induced apoptosis. Furthermore, ceramide activated protein phosphatase 1 (PP1), rather than PP2a, increased the translocation of alternative splicing factor ASF/SF2 from cytoplasm to nucleus and thus determined the pre-mRNA splicing for wild-type p53. Alternative pre-mRNA splicing not only generates more than one protein isoform from single gene, it also results in gene mutants in cancer and other diseases. Our study elucidates a previous unrecognized mechanism in regulating the expression of wild-type versus mutant protein of

p53 and indicates mutants can be restored in posttranscriptional levels by using an epigenetic approach.

Citation Format: Yong-Yu Liu, Gauri A. Patwardhan. Ceramide restores the expression of wild-type p53 tumor suppressor in mRNA splicing through PP1 and ASF/SF2. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3199. doi:10.1158/1538-7445.AM2013-3199

Ceramide glycosylation by glucosylceramide synthase selectively maintains the properties of breast cancer stem cells

Cancer stem cells are distinguished from normal adult stem cells by their stemness without tissue homeostasis control. Glycosphingolipids (GSLs), particularly globo-series GSLs, are important markers of undifferentiated embryonic stem cells, but little is known about whether or not ceramide glycosylation, which controls glycosphingolipid synthesis, plays a role in modulating stem cells. Here, we report that ceramide glycosylation catalyzed by glucosylceramide synthase, which is enhanced in breast cancer stem cells (BCSCs) but not in normal mammary epithelial stem cells, maintains tumorous pluripotency of BCSCs. Enhanced ceramide glycosylation and globotriosylceramide (Gb3) correlate well with the numbers of BCSCs in breast cancer cell lines. In BCSCs sorted with CD44(+)/ESA(+)/CD24(-) markers, Gb3 activates c-Src/β-catenin signaling and up-regulates the expression of FGF-2, CD44, and Oct-4 enriching tumorigenesis. Conversely, silencing glucosylceramide synthase expression disrupts Gb3 synthesis and selectively kills BCSCs through deactivation of c-Src/β-catenin signaling. These findings highlight the unexploited role of ceramide glycosylation in selectively maintaining the tumorous pluripotency of cancer stem cells. It speculates that disruption of ceramide glycosylation or globo-series GSL is a useful approach to specifically target BCSCs specifically.

Cellular stress response in Eca-109 cells inhibits apoptosis during early exposure to isorhamnetin

The flavonol aglycone isorhamnetin shows anti-proliferative activity in a variety of cancer cells. Previous work, from our laboratory showed that isorhamnetin inhibits the proliferation of human esophageal squamous carcinoma Eca-109 cells in vitro, but only after 72 h of exposure. This led us to propose that isorhamnetin exposure induces a cellular stress response that inhibits the antiproliferative and apoptotic effects of the compound during early exposure. To test this hypothesis, the present study examined the effects of isorhamnetin on Eca-109 cells during the first 72 h of exposure. Cell growth was assessed using the trypan blue exclusion assay, and expression of IκBα, NF-κB/p65, NF-κB/p50, phospho-Akt, Bcl-2, COX-2, Mcl-1, Bax, p53 and Id-1 were analyzed by Western blot. During the first 72 h of exposure, NF-κB/p65 and NF-κB/p50 accumulated in nuclei and expression of COX-2, Bcl-2 and Mcl-1 increased. In contrast, expression of IκBα and Bax fell initially but later increased. Expression of phospho-Akt and p53 showed no detectable change during the first 48 h. Pretreatment with the NF-κB inhibitor MG132 before exposure to isorhamnetin blocked the nuclear accumulation of p50 and p65, thereby inhibiting cell proliferation. These results show that during early exposure of Eca-109 cells to isorhamnetin, the NF-κB signaling pathway is activated and COX-2 expression increases, and this increase in expression partially inhibits isorhamnetin-induced apoptosis. Beyond 72 h of exposure, however, the apoptotic effect of isorhamnetin dominates, leading to inhibition of the NF-κB pathway and of cellular proliferation. These results will need to be taken into account when exploring the use of isorhamnetin against cancer in vivo.

The opposite effects of doxorubicin on bone marrow stem cells versus breast cancer stem cells depend on glucosylceramide synthase

Myelosuppression and drug resistance are common adverse effects in cancer patients with chemotherapy, and those severely limit the therapeutic efficacy and lead treatment failure. It is unclear by which cellular mechanism anticancer drugs suppress bone marrow, while drug-resistant tumors survive. We report that due to the difference of glucosylceramide synthase (GCS), catalyzing ceramide glycosylation, doxorubicin (Dox) eliminates bone marrow stem cells (BMSCs) and expands breast cancer stem cells (BCSCs). It was found that Dox decreased the numbers of BMSCs (ABCG2(+)) and the sphere formation in a dose-dependent fashion in isolated bone marrow cells. In tumor-bearing mice, Dox treatments (5mg/kg, 6 days) decreased the numbers of BMSCs and white blood cells; conversely, those treatments increased the numbers of BCSCs (CD24(-)/CD44(+)/ESA(+)) more than threefold in the same mice. Furthermore, therapeutic-dose of Dox (1mg/kg/week, 42 days) decreased the numbers of BMSCs while it increased BCSCs in vivo. Breast cancer cells, rather than bone marrow cells, highly expressed GCS, which was induced by Dox and correlated with BCSC pluripotency. These results indicate that Dox may have opposite effects, suppressing BMSCs versus expanding BCSCs, and GCS is one determinant of the differentiated responsiveness of bone marrow and cancer cells.

Curcumin blocks small cell lung cancer cells migration, invasion, angiogenesis, cell cycle and neoplasia through Janus kinase-STAT3 signalling pathway

Curcumin, the active component of turmeric, has been shown to protect against carcinogenesis and prevent tumor development. However, little is known about its anti-tumor mechanism in small cell lung cancer (SCLC). In this study, we found that curcumin can inhibit SCLC cell proliferation, cell cycle, migration, invasion and angiogenesis through suppression of the STAT3. SCLC cells were treated with curcumin (15 µmol/L) and the results showed that curcumin was effective in inhibiting STAT3 phosphorylation to downregulate of an array of STAT3 downstream targets ,which contributed to suppression of cell proliferation, loss of colony formation, depression of cell migration and invasion. Curcumin also suppressed the expression of proliferative proteins (Survivin, Bcl-X(L) and Cyclin B1), and invasive proteins (VEGF, MMP-2, MMP-7 and ICAM-1). Knockdown of STAT3 expression by siRNA was able to induce anti-invasive effects in vitro. In contrast, activation of STAT3 upstream of interleukin 6 (IL-6) leads to the increased cell proliferation ,cell survival, angiogenesis, invasion, migration and tumor growth. Our findings illustrate the biologic significance of IL-6/JAK/STAT3 signaling in SCLC progression and provide novel evidence that the pathway may be a new potential target for therapy of SCLC. It was concluded that curcumin is a potent agent in the inhibition of STAT3 with favorable pharmacological activity,and curcumin may have translational potential as an effective cancer therapeutic or preventive agent for SCLC.

Controlling magnetoelectric coupling by nanoscale phase transformation in strain engineered bismuth ferrite

The magnetoelectric coupling in multiferroic materials is promising for a wide range of applications, yet manipulating magnetic ordering by electric field proves elusive to obtain and difficult to control. In this paper, we explore the prospect of controlling magnetic ordering in misfit strained bismuth ferrite (BiFeO(3), BFO) films, combining theoretical analysis, numerical simulations, and experimental characterizations. Electric field induced transformation from a tetragonal phase to a distorted rhombohedral one in strain engineered BFO films has been identified by thermodynamic analysis, and realized by scanning probe microscopy (SPM) experiment. By breaking the rotational symmetry of a tip-induced electric field as suggested by phase field simulation, the morphology of distorted rhombohedral variants has been delicately controlled and regulated. Such capabilities enable nanoscale control of magnetoelectric coupling in strain engineered BFO films that is difficult to achieve otherwise, as demonstrated by phase field simulations.

Doxorubicin and MBO-asGCS oligonucleotide loaded lipid nanoparticles overcome multidrug resistance in adriamycin resistant ovarian cancer cells (NCI/ADR-RES)

The objective of this study was to increase the potency of doxorubicin against adriamycin-resistant NCI/ADR-RES cells by concurrent treatment with doxorubicin and MBO-asGCS loaded solid-lipid nanoparticles (SLN). Loading doxorubicin as ion-pair complex with deoxytaurocholate into cationic and neutral SLN was investigated. Fast release and poor entrapment were observed in cationic nanoparticles, which were corrected by entrapping the complex in neutral polyoxyethylene (20) stearyl ether (Brij(®) 78)/VitE-TPGS nanoparticles. Slow doxorubicin release confirmed the influence of charge and electrolytes on the dissociation of ion-pair complexes. To evaluate antitumor activity, NCI/ADR-RES cells were treated with separate SLN: one loaded with doxorubicin and another carrying MBO-asGCS oligonucleotide. The viability of cells treated with 5 μM doxorubicin was reduced to 17.2% whereas viability was reduced to 2.5% for cells treated with both 5 μM doxorubicin SLN and 100 nM MBO-asGCS SLN. This suggested enhanced apoptosis due to sensitization and effective intracellular delivery of MBO-asGCS and doxorubicin by SLN.

Effects of preventive acupuncture on streptozotocin-induced hyperglycemia in rats

BACKGROUND

Diabetes prevention has received increasing attention recently. Clinical and experimental studies showed that acupuncture could produce hypoglycemic effect. However, little is known about the effectiveness of acupuncture in diabetes prevention.

AIM

To investigate the preventive effects of acupuncture on streptozotocin (STZ)-induced hyperglycemia in rats.

METHODS

Hyperglycemia was induced by a single intraperitoneal injection of STZ (60 mg/kg). Rats were randomly divided into six groups (no.=8 each group): control, diabetes, preventive acupuncture plus STZ injection, STZ injection plus therapeutic acupuncture, STZ injection plus preventive and therapeutic acupuncture, and preventive and therapeutic acupuncture control. Body weight, blood glucose, serum insulin, lipid peroxidation, and antioxidant enzymes were measured by routine standard methods. Histological analysis of pancreatic islets was conducted.

RESULTS

Preventive acupuncture significantly relieved hyperglycemia, insulin deficiency, weight loss, and pancreatic islet damage in rats with STZ injection; it also significantly reduced serum lipid peroxidation and enhanced superoxide dismutase in the serum and the pancreas without significantly affecting serum glutathione peroxidase and catalase. Therapeutic acupuncture exhibited a hypoglycemic effect in the late stage, but did not significantly improve other parameters.

CONCLUSIONS

These results indicate that preventive acupuncture is beneficial to the control of STZ-induced hyperglycemia in rats.

Resuscitating wild-type p53 expression by disrupting ceramide glycosylation: a novel approach to target mutant p53 tumors

Mutant p53 is frequently detected in cancers in which p53 has lost its ability in tumor suppression and gained function in promoting tumor progression. Restoration of p53 functions by replacement of wild-type p53 and inhibition of its degradation or increment of its transcriptional activity has been applied to the prevention and treatment of cancers. Recent evidence indicates that disrupting ceramide glycosylation can resuscitate wild-type p53 expression and p53-dependent apoptosis in mutant p53 tumors. A posttranscriptional process that can turn on wild-type p53 expression and abrogate mutant p53 may provide a new strategy to eradicate mutant p53 cancers.

Mutant p53 exhibits trivial effects on mitochondrial functions which can be reactivated by ellipticine in lymphoma cells

Increasing evidence has shown that a fraction of the wild-type (wt) form of the tumor suppressor p53, can translocate to mitochondria due to genotoxic stress. The mitochondrial targets of wt p53 have also been studied. However, whether mutant p53, which exists in 50% of human cancers, translocates to mitochondria and affects mitochondrial functions is unclear. In this study, we used doxorubicin, a chemotherapeutic drug, to treat five human lymphoma cell lines with wt, mutant or deficient in p53, to induce p53 activation and mitochondrial translocation. Our results demonstrated that mutant p53, like wt p53, was induced upon doxorubicin treatment. Similarly, a fraction of mutant p53 also translocated to mitochondria. However, Complex I and II activities in the mitochondria were compromised only in wt p53-bearing cells after doxorubicin treatment, but not in mutant p53-bearing cells. Similarly, doxorubicin treatment caused greater cell death only in wt p53-bearing cells, but not in mutant p53-bearing cells. When p53 deficient Ramos cells were transfected with mutant p53 (249S), the cells showed resistance to doxorubicin-induced cell death and decreases in complex activities. To reactivate mutant p53 and reverse chemoresistance, ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole) was used to treat mutant p53 cells. Ellipticine enhanced p53 mitochondrial translocation, decreased Complex I activity, and sensitized p53 mutant cells to doxorubicin-induced apoptosis. In summary, our studies suggest that mutations in p53 may not hinder p53's mitochondrial translocation, but impair its effects on mitochondrial functions. Therefore, restoring mutant p53 by ellipticine may sensitize these cells to chemotherapy.

Molecular analysis of the coat protein gene of peanut stripe virus from China

Peanut stripe virus (PStV) is one of the most common viruses infecting peanut that causes great economic losses every year. The 3ʹ-terminal 1082 bp of 74 PStV isolates collected from 12 districts of Shandong province, China were sequenced. Their coat protein (CP) genes were 864 bp in length and shared identities of 98.0%~100% and 98.3% ~100% at nt and aa levels. The identities between the CP genes of these isolates and other 36 isolates from the GenBank were 93.5%~100% and 92.0%~100% at nt and aa levels, respectively. PStV isolates can be clustered into two phylogenetic groups. The isolates from United States, mainland China, and Indonesia formed group I and those from Viet Nam, Thailand, and Taiwan formed group II. The PStV isolates in group I can be further classified to two subgroups. The gene flow of PStV populations within a country was frequent, but that between countries was infrequent.

Glucosylceramide synthase, a factor in modulating drug resistance, is overexpressed in metastatic breast carcinoma

Drug resistance causes treatment failure in approximately 50% of breast cancer patients with chemotherapy. Overexpression of glucosylceramide synthase (GCS) confers drug resistance in cancer cells, and suppression of GCS sensitizes cancers to chemotherapy in preclinical studies. Thus, GCS becomes a potential target to reverse drug resistance; however, little is known about GCS expression levels in normal tissues and whether GCS overexpression is associated with metastatic cancers. Herewith, we report our studies in GCS expression levels and breast cancer from patients. GCS levels were analyzed using cancer profiling arrays, breast cancer histo-arrays and quantitative RT-PCR in tumor tissues. We found that breast (18 exp. index) and other hormone-dependent organs (testis, cervix, ovary, prostate) displayed the lowest levels of GCS mRNA, whereas liver (52 exp. index) and other organs (kidney, bladder, stomach) displayed the highest levels of GCS. GCS mRNA levels were significantly elevated in tumors of breast, cervix, rectum and small intestine, as compared to each paired normal tissue. In mammary tissue, GCS overexpression was detected in breast cancers with metastasis, but not in benign fibroadenoma or primary tumors. GCS overexpression was coincident with HER2 expression (γ2=0.84) in ER-negative breast adenocarcinoma. In tumor specimens, GCS mRNA was elevated by 4-fold and significantly associated with stage III (5/7), lymph node-positive (7/8) and estrogen receptor-positive breast cancers (7/9). GCS expression was significantly and selectively elevated in breast cancer, in particular in metastatic disease. GCS overexpression was highly associated with ER-positive and HER2-positive breast cancer with metastasis. Although a small study, these data suggest that GCS may be a prognostic indicator and potential target for the treatment of chemotherapy-refractory breast cancer.

Pharmacokinetics, tissue distribution and excretion study of dl-praeruptorin A of Peucedanum praeruptorum in rats by liquid chromatography tandem mass spectrometry

dl-Praeruptorin A (Pd-Ia), isolated from Chinese traditional herbal medicine Peucedanum praeruptorum Dunn, has been proved to be a novel Ca²+-influx blocker and K+-channel opener, and displayed bright prospects in prevention and therapy of cardiac diseases. The aim of this study was to investigate the pharmacokinetics, tissue distribution and excretion of Pd-Ia in rats following a single intravenous (i.v.) administration. The levels of Pd-Ia in plasma, tissues, bile, urine and feces were measured by a rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The results showed that Pd-Ia was rapidly distributed and then eliminated from rat plasma and manifested linear dynamics in dose range of 5-20 mg/kg. The mean elimination half-life (t(½) of Pd-Ia for 5, 10 and 20 mg/kg dose were 57.46, 60.87 and 59.01 min, respectively. The major distribution tissues of Pd-Ia in rats were spleen, heart and lung, and low polarity enabled Pd-Ia to cross the blood-brain barrier. There was no long-term accumulation of Pd-Ia in rat tissues. Total recoveries of Pd-Ia within 24 h were low (0.097% in bile, 0.120% in urine and 0.009% in feces), which might be resulted from liver first pass effect.