ML-1 Cells Research Articles

Transient Receptor Potential Canonical 1 (TRPC1) Channels as Regulators of Sphingolipid and VEGF Receptor Expression: IMPLICATIONS FOR THYROID CANCER CELL MIGRATION AND PROLIFERATION

The identity of calcium channels in the thyroid is unclear. In human follicular thyroid ML-1 cancer cells, sphingolipid sphingosine 1-phosphate (S1P), through S1P receptors 1 and 3 (S1P1/S1P3), and VEGF receptor 2 (VEGFR2) stimulates migration. We show that human thyroid cells express several forms of transient receptor potential canonical (TRPC) channels, including TRPC1. In TRPC1 knockdown (TRPC1-KD) ML-1 cells, the basal and S1P-evoked invasion and migration was attenuated. Furthermore, the expression of S1P3 and VEGFR2 was significantly down-regulated. Transfecting wild-type ML-1 cells with a nonconducting TRPC1 mutant decreased S1P3 and VEGFR2 expression. In TRPC1-KD cells, receptor-operated calcium entry was decreased. To investigate whether the decreased receptor expression was due to attenuated calcium entry, cells were incubated with the calcium chelator BAPTA-AM (1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid). In these cells, and in cells where calmodulin and calmodulin-dependent kinase were blocked pharmacologically, S1P3 and VEGFR2 expression was decreased. In TRPC1-KD cells, both hypoxia-inducible factor 1α expression and the secretion and activity of MMP2 and MMP9 were attenuated, and proliferation was decreased in TRPC1-KD cells. This was due to a prolonged G1 phase of the cell cycle, a significant increase in the expression of the cyclin-dependent kinase inhibitors p21 and p27, and a decrease in the expression of cyclin D2, cyclin D3, and CDK6. Transfecting TRPC1 to TRPC1-KD cells rescued receptor expression, migration, and proliferation. Thus, the expression of S1P3 and VEGFR2 is mediated by a calcium-dependent mechanism. TRPC1 has a crucial role in this process. This regulation is important for the invasion, migration, and proliferation of thyroid cancer cells.

Sonic hedgehog pathway inhibitor mitigates mouse hepatocellular carcinoma

BackgroundHepatocellular carcinoma (HCC) is a leading cause of death in Asian countries. Sonic hedgehog (Shh) pathway plays a role in hepatocarcinogenesis. We investigated the treatment effect of mouse HCC with Shh inhibitor GDC-0449. MethodsMouse hepatoma ML-1 cells were implanted in B6 mice. Fifteen days later, GDC-0449 (vismodegib), antagonist of smoothened, was used to treat HCC-bearing mice. The tumor size and liver histopathological features were analyzed, as well as gene expression in Shh pathways. ResultsGDC-0449 treatment effectively reduced tumor size and cell infiltration of the HCC in mice. Gene expression of Shh pathway molecules was altered, including upregulated Shh expression and downregulated smoothened expression in tumor fractions after GDC-0449 treatment. ConclusionGDC-0449 could effectively mitigate HCC growth in vivo.

MMP2 and MMP9 participate in S1P-induced invasion of follicular ML-1 thyroid cancer cells

The bioactive lipid sphingosine-1-phosphate (S1P) has emerged as a potent inducer of cancer cell migration and invasion. Previously, we have shown that S1P induces invasion of ML-1 follicular thyroid cancer cells via S1P receptors 1 and 3 (S1P1,3). Matrix metalloproteinases (MMPs) are zinc-dependent proteolytic enzymes used by cells for degradation of the extracellular matrix during invasion and migration. In the present study, we examined the role of MMP2 and MMP9 for S1P-induced invasion of ML-1 cells, and found that S1P regulates the secretion and activity of MMP2 and MMP9 via S1P1,3. Both pharmacological inhibitors and siRNA knockdown of MMP2 and MMP9 could attenuate S1P-induced invasion. Additionally, we show that calpains and Rac1 mediate S1P-induced secretion of MMP2 and MMP9. In conclusion, MMP2 and MMP9 participate in S1P-evoked follicular ML-1 thyroid cancer cell invasion.

Endoplasmic reticulum stress as a novel mechanism in amiodarone-induced destructive thyroiditis.

Amiodarone (AMIO) is one of the most effective antiarrhythmic drugs available; however, its use is limited by a serious side effect profile, including thyroiditis. The mechanisms underlying AMIO thyroid toxicity have been elusive; thus, identification of novel approaches in order to prevent thyroiditis is essential in patients treated with AMIO. Our aim was to evaluate whether AMIO treatment could induce endoplasmic reticulum (ER) stress in human thyroid cells and the possible implications of this effect in AMIO-induced destructive thyroiditis. Here we report that AMIO, but not iodine, significantly induced the expression of ER stress markers including Ig heavy chain-binding protein (BiP), phosphoeukaryotic translation initiation factor 2α (eIF2α), CCAAT/enhancer-binding protein homologous protein (CHOP) and spliced X-box binding protein-1 (XBP-1) in human thyroid ML-1 cells and human primary thyrocytes. In both experimental systems AMIO down-regulated thyroglobulin (Tg) protein but had little effect on Tg mRNA levels, suggesting a mechanism involving Tg protein degradation. Indeed, pretreatment with the specific proteasome inhibitor MG132 reversed AMIO-induced down-regulation of Tg protein levels, confirming a proteasome-dependent degradation of Tg protein. Corroborating our findings, pretreatment of ML-1 cells and human primary thyrocytes with the chemical chaperone 4-phenylbutyric acid completely prevented the effect of AMIO on both ER stress induction and Tg down-regulation. We identified ER stress as a novel mechanism contributing to AMIO-induced destructive thyroiditis. Our data establish that AMIO-induced ER stress impairs Tg expression via proteasome activation, providing a valuable therapeutic avenue for the treatment of AMIO-induced destructive thyroiditis.

Abstract 468: Cancer cells with G/G mdm2 SNP309 have compromised transcriptional elongation of p53 target genes

Abstract MDM2 protein is often found over-expressed in cancers with wild-type p53. A single nucleotide polymorphism (T to G) near the mdm2 P2 promoter, mdm2 SNP309, leads to MDM2 overexpression. This polymorphism is associated with accelerated tumor formation, decreased sensitivity to DNA damage treatment and compromised p53 transcriptional activity. Two G/G SNP309 cell lines MANCA (Burkitt lymphoma) and A875 (melanoma) express wild-type p53 protein not readily degraded by MDM2. This wild-type p53 does not activate target genes even after DNA damage. During the blocked transcription, MDM2 and p53 co-localize at p53 response elements on chromatin. Therefore, we hypothesized that MDM2 localized with p53 on the chromatin was the contributing factor for the compromised p53 transcriptional activity. We explored the mechanism for compromised p53 transcriptional activity in these G/G SNP309 cancer cell lines. When compared to fully activated wild-type p53 in ML-1 cells treated with etoposide, MANCA and A875 cell lines had comparable recruitment of total and initiated RNA pol II at transcription start sites (TSS) for p21 and puma genes. This indicated that G/G SNP309 cells had functional transcription initiation at p53 target genes after DNA damage treatment. We next assessed epigenetic modifications associated with active transcriptional elongation. Using H3K36 trimethylation (H3K36me3) as a hallmark for active elongation, we observed that ML-1 cells had a substantial increase in H3K36me3 after etoposide treatment at p21 and puma TSS that was not seen in MANCA or A875 cell lines. This lack of H3K36me3 suggested an inhibition in early transcriptional elongation. To address the participation of MDM2 in the elongation block we created a stable MDM2 knockdown MANCA cell line. Interestingly, MDM2 knockdown drastically increased MDMX protein levels and moderately increased activation of p53 target genes implying MDMX played a redundant role for MDM2. We are currently investigating the roles of MDM2 and MDMX in blocking transcriptional elongation. Interestingly, we have found that treatment of MANCA cells with low dose Actinomycin D reactivates the p53 pathway and studies are in progress to determine if this is through activation of transcriptional elongation. This work was supported by The Breast Cancer Research Foundation and The National Science Foundation (grant MCB-0744316) to J.B. M.R. was supported by the MBRS-RISE Program to Hunter College 3R25-GM060665. Citation Format: Melissa Rosso, Alla Polotskaia, Jill Bargonetti. Cancer cells with G/G mdm2 SNP309 have compromised transcriptional elongation of p53 target genes. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 468. doi:10.1158/1538-7445.AM2014-468

Abstract 3059: Detection and characterization of circulating tumor cells by imaging flow cytometry

Abstract Introduction The clinical utility of circulating tumour cell enumeration as a prognostic indicator has been demonstrated in numerous carcinomas. However, poor quality images and limited characterisation available on the main platform used for CTC enumeration hamper the exploitation of CTCs in other areas of clinical oncology. Additionally, the reliance on the expression of EpCAM for the detection of CTCs limits detection of cells that have undergone epithelial/mesenchymal transition, and may therefore not directly detect metastatic precursor cells. In contrast, flow cytometric methods of CTC enumeration which allow multiple markers to be used simultaneously, are more sensitive than microscopy methods, but carry the caveat that cellular debris may not be resolvable from cells with a high degree of confidence. Our aim was to establish the sensitivity of detection of CTCs by imaging flow cytometry. Methods ML-1 follicular thyroid carcinoma cells were spiked into 4 ml whole blood from healthy volunteers collected into EDTA vacutainers to give concentrations of 500, 50 or 5 cells per ml. The samples were subjected to red blood cell lysis and fixation. CD45 positive leukocytes were then depleted by immuno-magnetism using a CD45 antibody. The remaining cells were permeabilised and stained with flurochrome conjugated primary antibodies to thyroglobulin, sodium iodide symporter, EpCam, cytokeratin, vimentin and CD45 as well as DAPI as a nuclear stain. The stained cells were processed using an imaging flow cytometer. Results Preliminary experiments to validate the specificity of the antibodies indicated the potential importance of heterogeneity as revealed by multi parameter staining. Only 8 ± 3.6% of ML-1 cells with a mesenchymal phenotype (EpCAM -ve/Vimentin+ve) were in G2 compared with 32 ± 8.7% cells from the same culture with a more epithelial (EpCAM +ve/Vimentin-ve) phenotype (mean and SD of three independent experiments, p = 0.012 T-test). Recovery experiments following red cell lysis and CD45 depletion of spiked cell samples gave >90% depletion of leukocytes and 48 ± 5%, 56 ± 15% and 78 ± 32% recovery at spiking densities of 500, 50 and 5 cells per ml respectively (mean and SD of three independent experiments). Discussion The method described allows the capture of multi-parameter high quality fluorescent images of extremely rare cell populations in a whole blood matrix and we are currently applying it to clinical samples derived from cancer patients and healthy volunteers. The method is also readily transferable to the detection of CTCs from other tumours by the substitution of tumour/tissue specific antibodies and optical space remains for the introduction of two additional probes. We will exploit this by incorporating probes for pharmacodynamic biomarkers specific to compounds in early phase clinical trials, thus allowing simultaneous PD assays in CTCs as a liquid biopsy and residual haematopoietic cells as a surrogate tissue. Citation Format: Barry Dent, Rachel L. O'Donnell, Laura F. Ogle, Emma D. Rourke, Hamsavardhini P. Ramesh, Maddie Moat, Nick Hayes, Ujjal K. Mallick, Felicity EB May, Helen L. Reeves, Nicola J. Curtain, Richard J. Edmondson, Alan V. Boddy, Ruth Plummer, David Jamieson. Detection and characterization of circulating tumor cells by imaging flow cytometry. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3059. doi:10.1158/1538-7445.AM2014-3059

Uncovering Cardioprotective Strategies For Anthracycline Therapy By Analysis Of Redox and Apoptotic Effects

Anthracyclines are among the most powerful drugs used for the treatment of leukemia, however their use has been associated with cardiotoxicity. Reactive oxygen species (ROS) are generated in both cancer and normal cells after anthracycline exposure and have been implicated in both early and late onset cardiotoxicity. Counteracting this ROS generation are intracellular antioxidants such as the ubiquitous antioxidant glutathione (GSH), levels of which are depleted upon anthracycline exposure. Basal expression of GSH pathway components and other antioxidants vary greatly between different cell types. Due to this differential expression of cellular antioxidants in cardiomyocytes versus leukemia cells, we posit that anthracyclines exert distinct effects on oxidative stress and consequent apoptosis induction in leukemia cells and nontransformed hematopoietic cells (PBMC) relative to cardiomyocytes. As a result, we expect potentially varied mechanisms of cell death induction in these cell lines after anthracycline treatment. To test this hypothesis, the acute leukemia cell lines Jurkat and ML-1 and the cardiomyocyte line H9C2 were used. Dose responses with the anthracyclines, doxorubicin and daunorubicin, were carried out and trypan blue exclusion and propidium iodide staining followed by flow cytometry were used to assess viability and DNA fragmentation respectively. Cardiomyocytes had a 25-150 fold higher IC50 value than the acute leukemia cell lines, indicating selectivity. To assess whether apoptosis was induced by anthracyclines, caspase 3 activity was measured and found to be increased at 24 hours in Jurkat cells which preceded decreases in viability, supporting an apoptotic mechanism of cell death. GSH levels also decreased markedly after 24 hours of treatment with anthracyclines in this cell line, however, a pan-caspase inhibitor did not block GSH depletion, indicating that these events occur independent of each other. To evaluate whether antioxidants conferred protection against loss of viability in all cell types, cells were pretreated for at least 30 minutes with antioxidants and then treated with doxorubicin and daunorubicin for 24 hours. Antioxidants used were N-acetylcysteine (NAC, a GSH precursor and amino acid source), GSH ethyl ester (cell permeable form of GSH), tiron (free radical scavenger) and trolox (a water soluble form of vitamin E). GSH ethylester did not prevent cytotoxicity of anthracyclines in acute leukemia lines or cardiomyocytes. Therefore boosting GSH levels in leukemia cells does not reverse cytotoxicity. Trolox, however, did block anthracycline induced cell death in ML-1 cells, suggesting that vitamin E supplementation would counteract leukemia cell specific effects of anthracyclines on AML cells. Tiron protected PBMC from doxorubicin cytotoxicity but did not protect leukemia cells or cardiomyocytes, hinting at a protective strategy for normal non-leukemia blood cells. Interestingly, NAC did not interfere with the cytotoxic effects of anthracyclines on acute leukemia cells or PBMC, but protected H9C2 cells from daunorubicin cytotoxicity. Taken together, these data reveal differential protective effects of antioxidants in cardiomyocytes and PBMCs relative to ALL and AML cells. Our work indicates that NAC can protect cardiomyocytes without interfering with anthracycline cytotoxicity in acute leukemia cells. In humans, one randomized control trial tested the addition of NAC to doxorubicin therapy, detecting no evidence of cardioprotective activity by chronic administration of NAC. However, the schedule used for administration of NAC in that study may not have been optimal, and biomarkers for oxidative stress reduction by NAC were not incorporated into the trial. Previously, other antioxidants have been used with very limited clinical success and possible contributing factors include inadequate sample size, choice of agent, dose used, duration of intervention and the lack of biomarker endpoints. Designing a cardioprotective and antioxidant strategy with attention to these factors may prove to be efficacious in protecting cardiac cells without interfering with the antitumoral effect of anthracyclines. To this end, our data suggests that trolox and vitamin E analogues should not be used in acute leukemia as they may interfere with the cytotoxic action of anthracyclines but NAC or cysteine may be used as cardioprotectants. Disclosures:No relevant conflicts of interest to declare.

Hepatitis C Virus Infection of a Thyroid Cell Line: Implications for Pathogenesis of Hepatitis C Virus and Thyroiditis

Autoimmune and non-autoimmune thyroiditis frequently occur in persons with hepatitis C virus (HCV) infection. Treatment with interferon alpha (IFNα) is also associated with significant risk for the development of thyroiditis. To explore HCV-thyroid interactions at a cellular level, we evaluated whether a human thyroid cell line (ML1) could be infected productively with HCV in vitro. ML1 cells showed robust surface expression of the major HCV receptor CD81. Using a highly sensitive, strand-specific reverse transcription polymerase chain reaction assay, positive-sense and negative-sense HCV RNA were detected in ML1 cell lysates at days 3, 7, and 14 postinfection with HCV. HCV core protein was expressed at high levels in ML1 supernatants at days 1, 3, 5, 7, and 14 postinfection. The nonstructural protein NS5A was also detected in ML1 cell lysates by Western blotting. HCV entry into ML1 cells was shown to be dependent on the HCV entry factors CD81 and SR-B1/CLA1, while IFNα inhibited HCV replication in ML1 cells in a dose-dependent manner. Supernatants from HCV-infected ML1 cells were able to infect fresh ML1 cells productively, suggesting that infectious virions could be transferred from infected to naïve thyroid cells in vivo. Additionally, HCV infection of ML1 cells led to increased expression of the pro-inflammatory cytokine IL-8. For the first time, we have demonstrated that HCV can infect human thyroid cells in vitro. These findings strongly suggest that HCV infection of thyrocytes may play a role in the association between chronic HCV infection and thyroid autoimmunity. Furthermore, the thyroid may serve as an extrahepatic reservoir for HCV viral replication, thus contributing to the persistence of viral infection and to the development of thyroid autoimmunity.

Sphingosine-1-Phosphate as a Regulator of Hypoxia-Induced Factor-1α in Thyroid Follicular Carcinoma Cells

Sphingosine-1-phosphate (S1P) is a bioactive lipid, which regulates several cancer-related processes including migration and angiogenesis. We have previously shown S1P to induce migration of follicular ML-1 thyroid cancer cells. Hypoxia-induced factor-1 (HIF-1) is an oxygen-sensitive transcription factor, which adapts cells to hypoxic conditions through increased survival, motility and angiogenesis. Due to these properties and its increased expression in response to intratumoral hypoxia, HIF-1 is considered a significant regulator of tumor biology. We found S1P to increase expression of the regulatory HIF-1α subunit in normoxic ML-1 cells. S1P also increased HIF-1 activity and expression of HIF-1 target genes. Importantly, inhibition or knockdown of HIF-1α attenuated the S1P-induced migration of ML-1 cells. S1P-induced HIF-1α expression was mediated by S1P receptor 3 (S1P3), Gi proteins and their downstream effectors MEK, PI3K, mTOR and PKCβI. Half-life measurements with cycloheximide indicated that S1P treatment stabilized the HIF-1α protein. On the other hand, S1P activated translational regulators eIF-4E and p70S6K, which are known to control HIF-1α synthesis. In conclusion, we have identified S1P as a non-hypoxic regulator of HIF-1 activity in thyroid cancer cells, studied the signaling involved in S1P-induced HIF-1α expression and shown S1P-induced migration to be mediated by HIF-1.

Notch/HES1 Implicated As a Tumor Suppressor Mechanism in Human AML in Vivo

Abstract 3524 Background:Although Notch signaling contributes to T cell leukemogenesis, the role of Notch in human AML is unclear. We and others have found that activation of Notch signaling inhibits AML growth and survival, e.g. a tumor suppressor like effect. However it is not known what the consequences of activating or inhibiting Notch signaling are in human AML in vivo. Approach:To determine whether Notch signaling would have growth inhibiting effects in vivo, we stably-transduced ML1 human AML cells with the constitutively-active forms of Notch1 and Notch2 (ICN1, ICN2), the common Notch target gene Hairy/Enhancer of Split 1 (HES1) or the pan-Notch inhibitor dominant-negative Mastermind-like (dnMAML) and performed in vivo competitive proliferation assays. Briefly, following transduction, each vector type were sorted to 50% GFP+ (containing the gene of interest) and GFP- (untransduced control cells). Groups of NSG mice were injected with these 50:50 mixtures of ML1 cells, and peripheral blood levels of GFP- and GFP+ cells were measured with flow cytometry for anti-human CD45 and GFP. Results:Peripheral blood engraftment of human CD45+ ML1 cells by week 5 was similar (2–5%) for ICN1, ICN2 and HES1 injected mice, but was significantly higher (23%) in dnMAML injected mice (Panel A). Similar to in vitro competitive proliferation assays, ICN1, ICN2 and HES1 all led to decreased relative numbers of GFP%+ cells, with 1%, 4% and 16% respectively (Panel B). Importantly, dnMAML had little effect on AML proliferation in vitro, however led to dramatic increases in GFP% as well as early morbidity and mortality due to increased leukemia burden, with 93% GFP+ (Panel B), demonstrating a selective advantage for dnMAML-expressing ML1 in vivo. When GFP+ (transduced) ML1 peripheral engraftment was directly compared to GFP- (parental CD45+) engraftment, the GFP- control cells had similar engraftment rates (2–5%) across groups of mice, while the GFP+ engraftment rates were significantly lower in ICN1, ICN2, and HES1 groups, but significantly higher in the dnMAML group (Panel C), demonstrating enhanced engraftment/proliferation in dnMAML-expressing cells. Conclusions:This suggests a previously unreported concept, namely that endogenous Notch ligands can inhibit human AML growth in vivo. This data supports the hypothesis that Notch behaves as a tumor suppressor in AML, and suggests the potential use of Notch agonists in human AML. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Upregulation of TLR1, TLR2, TLR4, and IRAK-2 Expression During ML-1 Cell Differentiation to Macrophages: Role in the Potentiation of Cellular Responses to LPS and LTA

12-O-tetradecanoylphorbol 13-acetate (TPA) induces the differentiation of human myeloid ML-1 cells to macrophages. In the current study, the expression, responsiveness, and regulation of toll-like receptors (TLRs) in TPA-induced ML-1-derived macrophages were investigated. We have found that TPA-induced differentiation of ML-1 cells was accompanied by the upregulation of TLR1, TLR2, TLR4, and CD14 expression at both the mRNA and protein levels. Interestingly, TLR1 and TLR4 protein expression on ML-1 cells could be blocked by pretreatment with U0126, suggesting the role of an Erk1/2-induced differentiation signal in this process. In addition, the expression of IRAK-2, a key member of the TLR/IRAK-2/NF-κB-dependent signaling cascade was also induced in response to TPA. Accordingly, we demonstrated an increased cellular release of inflammatory cytokines (TNF-α and various interleukins) upon stimulation with LPS and LTA ligands for TLR4 and TLR2, respectively. Furthermore, using luminol-dependent chemiluminescence, addition of LPS and LTA induces a sustained DPI-inhibitable generation of reactive oxygen species (ROS) by the differentiated ML-1 cells. Together, these data suggest that the increase in the responsiveness of TPA-treated ML-1 cells to LPS and LTA occurs in response to the upregulation of their respective receptors as well as an induction of the IRAK-2 gene expression.

Estrogen-Mediated Angiogenesis in Thyroid Tumor Microenvironment Is Mediated Through VEGF Signaling Pathways

To explore the induction of a proangiogenic phenotype in endothelial cells in the thyroid tumor microenvironment by estrogen-treated thyroid cancer cells and to define the role of vascular endothelial growth factor (VEGF) in this interaction. Cell-based in vitro systems analysis. Thyroid tumor cell lines (BCPAP [papillary thyroid cancer] and ML-1 [follicular thyroid cancer]) were cultured with estradiol with and without an estrogen receptor (ER) inhibitor (fulvestrant or ICI) and used to treat human umbilical vein endothelial cells (HUVECs). Immunofluorescence was used to confirm the presence of ERα and ERβ in BCPAP cells. Conditioned medium was then used to evaluate the induction of HUVEC tubulogenesis and migration. Secretion of VEGF in this medium was evaluated by Western blot analysis. The expression of phosphoinositide 3-kinase (PI3K), the initiator of a proangiogenic pathway, was evaluated with Western blot analysis of HUVEC lysates. The subsequent effects of an ER inhibitor (fulvestrant/ICI) and a neutralizing VEGF antibody were also observed. Estrogen receptor α and ERβ are expressed in thyroid cancer cells. Estrogen-stimulated ML-1 cells secreted an increased amount of VEGF likely as a result of ER signaling. In contact with this environment, HUVECs demonstrate enhanced tubulogenesis and migration. Western blot analysis documented estrogen-mediated upregulation of PI3K in HUVECs. These effects were mitigated by an ER inhibitor (fulvestrant/ICI) and a neutralizing VEGF antibody. Our data provide evidence that estrogen can induce a proangiogenic endothelial cell phenotype in the thyroid tumor microenvironment through ER and VEGF signaling. Our findings suggest that the effect of antiestrogenic therapy targeting tumor angiogenesis can be enhanced through VEGF inhibition.

Differential Gene Regulation under Altered Gravity Conditions in Follicular Thyroid Cancer Cells: Relationship between the Extracellular Matrix and the Cytoskeleton

Extracellular matrix proteins, adhesion molecules, and cytoskeletal proteins form a dynamic network interacting with signalling molecules as an adaptive response to altered gravity. An important issue is the exact differentiation between real microgravity responses of the cells or cellular reactions to hypergravity and/or vibrations. To determine the effects of real microgravity on human cells, we used four DLR parabolic flight campaigns and focused on the effects of short-term microgravity (22 s), hypergravity (1.8 g), and vibrations on ML-1 thyroid cancer cells. No signs of apoptosis or necrosis were detectable. Gene array analysis revealed 2430 significantly changed transcripts. After 22 s microgravity, the F-actin and cytokeratin cytoskeleton was altered, and ACTB and KRT80 mRNAs were significantly upregulated after the first and thirty-first parabolas. The COL4A5 mRNA was downregulated under microgravity, whereas OPN and FN were significantly upregulated. Hypergravity and vibrations did not change ACTB, KRT-80 or COL4A5 mRNA. MTSS1 and LIMA1 mRNAs were downregulated/slightly upregulated under microgravity, upregulated in hypergravity and unchanged by vibrations. These data indicate that the graviresponse of ML-1 cells occurred very early, within the first few seconds. Downregulated MTSS1 and upregulated LIMA1 may be an adaptive mechanism of human cells for stabilizing the cytoskeleton under microgravity conditions.

Gnidilatimonoein from Daphne mucronata induced differentiation and apoptosis in leukemia cell lines

Among various treatments, plants play a crucial role in cancer chemotherapy. Base on literature data, different species of the thymeleaeceae family have been found to be good sources for anticancer agents. Therefore, our laboratory has initiated a research project on evaluating the anticancer properties of the Iranian medical plant, Daphne mucronata (Thymeleaeceae). Gnidilatimonoein is a new diterpene ester compound that is purified from Daphne mucronata with antiproliferative and anti-metastatic effects in different tumor cell lines. Based on the inhibitory role of this agent on the cell cycle progression of K562 cell line, we were interested to check gnidilatimonoein for induction of differentiation and apoptosis in different human leukemia ML-1, HL-60 and K562 cells. Cell viability was determined by trypan blue exclusion method. Cell differentiation was studied in terms of morphology, NBT reduction in leukemia cells (HL-60 and ML-1) and benzidine staining in erythroleukemia (K562) cells. Apoptosis was detected by fluorescence microscopy (Acridine orange/Ethedium bromide double staining), annexineV flow cytometry and DNA electrophoresis. After 48 hours of treatment with 10 µM gnidilatimonoein, 80-70% of HL-60 and ML1 cells showed NBT reduction. Indeed gnidilatimonoein induced monocyte differentiation of myeloid leukemia HL-60 and ML-1 cells but not K562 erythroluekemia cells. In this condition, we observed the growth inhibitory effect (60%) without substantial loss of viability (

Involvement of apoptosis and autophagy in reducing mouse hepatoma ML-1 cell growth in inbred BALB/c mice by bacterial fermented soybean products

Followed by the results of our previous in vitro report (Food Chem. Toxicol., 2007), the efficacy of the soybean fermentation products containing live bacteria (SCB) was demonstrated using a syngeneic animal model. Murine HBV-related hepatoma ML-1 cells, derived from inbred animals and tumorigenic in BALB/c mice, were implanted subcutaneously to the flank of BALB/c mice on day 0. Three days after implantation, SCB (1.0 or 1.3ml/mouse/day) or vehicle (water) was orally administrated daily until day 60. The results indicate that SCB significantly reduced (P<0.05) the volumes and weights of tumors during the experimental periods. Examination using TUNEL staining on section of tumors revealed apoptotic phenomenon of nuclear DNA double-strand breaks in the groups of mice received SCB. Immunohistochemistry further revealed an autophagic LC3-II punctate pattern. Of note, SCB induced autophagy in the absence or presence of apoptosis, whereas, apoptosis was observed only in combination with autophagy. In vitro study using autophagy inhibitor indicated that the induction of autophagy promoted apoptosis. These data imply that the suppression in tumor volumes and tumor weights by oral administration of SCB was due to the induction of apoptotic and autophagic cell death, which suggests therapeutic potential of SCB on HBV-related HCC.

S1P1 and VEGFR-2 Form a Signaling Complex with Extracellularly Regulated Kinase 1/2 and Protein Kinase C-α Regulating ML-1 Thyroid Carcinoma Cell Migration

Sphingosine 1-phosphate (S1P) and vascular endothelial growth factor receptor 2 (VEGFR-2) signaling have been shown to integrate in many biological processes. The follicular thyroid carcinoma cell line ML-1 expresses VEGFR-2 and secretes substantial amounts of both vascular endothelial growth factor (VEGF)-A and VEGF-C. ML-1 cells also express S1P-receptors (S1P(1-3,5)). S1P is able to phosphorylate VEGFR-2, and inhibiting VEGFR-2 attenuates S1P-induced migration and down-regulates S1P(1) expression in ML-1 cells. In the present study, we focused on the interactions between S1P(1) and VEGFR-2. We show that S1P receptors form complexes with VEGFR-2 and that the S1P(1)/VEGFR-2 complex associates with protein kinase C (PKC)-alpha and ERK1/2. Furthermore, the complex evokes bidirectional signaling since the S1P-induced ERK1/2 phosphorylation is sensitive to VEGFR-2 kinase inhibition and VEGF-A-induced ERK1/2 phosphorylation is sensitive to pertussis toxin treatment as well as S1P(1) small interfering RNA (siRNA) treatment. Both S1P- and VEGF-A-induced haptotaxis is sensitive to pertussis toxin treatment and S1P(1) siRNA treatment. Phosphorylation of ERK1/2 evoked by both VEGF-A and the S1P(1) agonist SEW-2871 is inhibited by PKC-alpha and PKC-betaI siRNA. We hypothesize that VEGFR-2 forms a signaling complex with S1P(1), evoking bidirectional signaling regulating both ERK1/2 phosphorylation and haptotaxis of ML-1 cells.

Hepatitis B virus surface antigen interacts with acid alpha‐glucosidase and alters glycogen metabolism

Hepatitis B virus (HBV) infection is highly correlated with hepatocellular carcinoma. Previous studies have reported that expression of hepatitis B virus pre-S2 mutant surface antigen is related to hepatoma development. An aberrant carbohydrate metabolism is a hallmark of malignant transformation. We performed yeast two-hybrid screening with HBV pre-S2-del large surface protein (pre-S2Delta) by using human liver cDNA library, and identified the acid alpha-glucosidase (acid alpha-glucosidase) as the novel cellular interacting protein of pre-S2Delta. The association of pre-S2Delta with the acid alpha-glucosidase was confirmed by confocal immunofluorescence and co-immunoprecipitation assay. Further, the acid alpha-glucosidase activity and glycogen content were analyzed in ML-1 cells expressing pre-S2Delta. The interaction between HBV large surface protein and acid alpha-glucosidase was demonstrated with co-immunoprecipitation in vitro and in vivo, and the binding was mediated through c-terminal region 889-952 amino acid of acid alpha-glucosidase. On the other hand, HBV large surface protein interacted with acid alpha-glucosidase through N-terminal region 1-157 amino acid of HBV large surface protein. Expression of HBV large surface protein enhanced acid alpha-glucosidase activity and resulted in decrease of cellular glycogen. Our result demonstrates that HBV large surface protein interacts with acid alpha-glucosidase which plays an important role in glycogen balance. Together, these data suggest a novel pathway by which HBV large surface protein affects carbohydrate metabolism.

Vinblastine Induces Acute, Cell Cycle Phase–Independent Apoptosis in Some Leukemias and Lymphomas and Can Induce Acute Apoptosis in Others when Mcl-1 Is Suppressed

Chemotherapeutic agents modify intracellular signaling that culminates in the inhibition of Bcl-2 family members and initiates apoptosis. Inhibition of the extracellular signal-regulated kinase by PD98059 dramatically accelerates vinblastine-mediated apoptosis in ML-1 leukemia with cells dying in 4 hours from all phases of the cell cycle. Inhibition of protein synthesis by cycloheximide also markedly accelerated vinblastine-induced apoptosis, showing that the proteins required for this acute apoptosis are constitutively expressed. Vinblastine induced the rapid induction of Mcl-1 that was inhibited by PD98059 and cycloheximide. No change in Bcl-2 or Bcl-X was observed. We hypothesize that ML-1 cells use Mcl-1 for protection from the rapid vinblastine-induced apoptosis. This was confirmed by targeting Mcl-1 with short hairpin RNA. We also investigated the response of 13 other leukemia and lymphoma cell lines and cells from seven chronic lymphocytic leukemia patients. Four cell lines and all chronic lymphocytic leukemia cells were killed in 6 hours by vinblastine alone. Two additional cell lines were sensitized to vinblastine by PD98059, which suppressed Mcl-1. This acute apoptosis either alone or in combination with PD98059 required vinblastine-mediated activation of c-Jun-NH(2)-terminal kinase. PD98059 did not suppress Mcl-1 in other cell lines whereas sorafenib did, but this did not sensitize the cells to vinblastine, suggesting that the acute apoptosis varies depending on which Bcl-2 protein mediates protection. Most of the cell lines were sensitized to vinblastine by cycloheximide, suggesting that inhibition of a short-lived protein in addition to Mcl-1 can acutely sensitize cells. These results suggest several clinical strategies that might provide an effective therapy for selected patients. Mol Cancer Ther; 9(4); 791-802. (c)2010 AACR.

Changes of Apoptosis, p53, and bcl-2 by Irradiation in Poorly Differentiated Thyroid Carcinoma Cell Lines: A Prognostic Marker for the Prospect of Therapeutic Success?

Poorly differentiated thyroid carcinoma (PDTC) has an unfavorable prognosis. Surgical management is the principal treatment approach. In addition, radioiodine treatment and external beam radiotherapy (EBRT) are given to reduce the risk of local relapse. Despite aggressive therapy, the response to treatment tends to become increasingly poorer over time. The objective of this study was to investigate the induction of apoptosis by EBRT as a function of p53 and bcl-2 protein levels in PDTC. The predictive value of these molecules with respect to treatment efficacy was evaluated. Two different cell lines of PDTC (FTC-133 and ML-1) were irradiated with a dose of 30 Gy. Apoptotic cells were quantified using terminal deoxynucleotidyltransferase-dUTP nick-end labeling staining without irradiation, 48 and 96 hours after irradiation. The protein levels of p53 and bcl-2 were measured simultaneously using flow cytometry and western blotting. The cell cycle distribution was determined. Untreated FTC-133 cells showed a high rate of apoptosis, a high protein level of p53, and a low bcl-2 protein level. Forty-eight hours after irradiation, a slight reduction in apoptotic cells was observed in conjunction with an increase in bcl-2 and p53 protein levels. The slightly reduced fraction of apoptotic cells remained at the same level up to 96 hours after irradiation, whereas the p53 protein level was further downregulated. The cell cycle distribution showed a significant G2/M arrest after 48 hours and recovery 96 hours after irradiation. ML-1 cells did not show any detectable p53 levels and revealed a low rate of apoptosis which significantly increased 48 hours after irradiation. Ninety-six hours after irradiation, a decrease in apoptosis was detectable. The protein level of bcl-2 increased significantly within 48 hours and decreased 96 hours after irradiation. The cell cycle distribution showed a G2/M arrest after 48 hours without a recovery 96 hours after irradiation. The p53 and bcl-2 expression profiles and the observed apoptotic rates of FTC-133 and ML-1 under irradiation are consistent with a more aggressive FTC-133 phenotype. Alterations in p53- and bcl-2 protein levels yield predictive information for EBRT efficacy.

“Limiting Anthracycline-Induced Cardiotoxicity Using Amrubicin in Leukemia Systems”.

Abstract 3760Poster Board III-696The overall survival of pediatric cancer patients has greatly improved over the last forty years in part due to the introduction of anthracyclines into therapeutic regimens. However, a significant limitation of anthracyline use is cardiotoxicity by this class of drugs. The mechanism most often cited as contributing to anthracycline cardiotoxicity is the production of reactive oxygen species (ROS) and subsequent damage to mitochondria, resulting in activation of the apoptotic cascade. Because heart tissue contains more mitochondria than other organ sites, this mechanism is particularly damaging to this organ site. Newer, less toxic anthracyclines are being developed and amrubicin, a completely synthetic anthracycline with potent topoisomerase II inhibition, is one such compound and is approved in Japan for the treatment of small cell and non-small cell lung cancer. In animal studies amrubicin has demonstrated decreased cardiotoxicity compared to doxorubicin, and in Phase I/II clinical trials in lymphomas and solid tumors has demonstrated single agent activity and an improved early cardiotoxicity profile. Our goal was to elucidate the role of ROS in the decreased cardiotoxicity observed with amrubicin exposure and to test the ability of amrubicin to promote cell death in leukemia cells.We used a rat cardiomyocyte cell line model (H9c2 cells) to quantify oxidative stress after exposure to amrubicin or other anthracyclines. Flow cytometry was used to evaluate superoxide levels after the cells were treated for 24 hours and stained with hydroethidium (HE). Interestingly, at equimolar doses (500 nM, 1 μM, 2 μM and 3 μM), cardiomyocytes treated with amrubicin produced less superoxide than cells treated with an equivalent dose of daunorubicin. These results suggest that ROS-mediated damage to cardiomyocytes is less after amrubicin exposure as compared to daunorubicin. The anti-leukemia efficacy of amrubicin was also evaluated as compared to other anthracyclines. Apoptosis induction in three different acute lymphocytic and myelocytic leukemia cell lines; Jurkat, ML-1 and KG-1 was measured using propidium iodide staining followed by flow cytometric analysis to yield cell cycle distributions. The percentage of the population with subdiploid amounts of DNA were representative of cells undergoing apoptotic DNA fragmentation. Using this method, we found that all three anthracyclines caused cell death after 24 hours of exposure. In order to assess the role of oxidative stress in anthracycline mediated cell death in leukemia cells, we measured ROS levels using equipotent doses of the drugs that elicited a 50% increase in the subdiploid population at 24 hours. In Jurkat and ML-1 cells both daunorubicin and doxorubicin significantly increased superoxide levels compared to control. Amrubicin also increased superoxide levels in Jurkat cells compared to cells treated with diluent alone. To establish a relationship between the observed oxidative stress and DNA fragmentation, we treated Jurkat cells with daunorubicin and doxorubicin with and without pretreatment with NAC (N-acetyl-cysteine), an antioxidant. NAC pretreatment significantly decreased superoxide levels, but did not abrogate the anthracyclines' promotion of apoptotic DNA fragmentation.These results suggest that ROS may not be essential for anthracycline cytotoxicity in leukemia cells. Since ROS are promoting cardiotoxic effects, yet appear dispensible for anti-leukemia effects, anthracyclines that cause less ROS, such as amrubicin, may prove to be better treatment options in pediatric cancer patients for whom anthracycline exposure is indicated. Furthermore, our data raises the possibility that amrubicin's decreased cardiotoxicity could be enhanced by administering antioxidants to patients without compromising the drug's anti-tumor effects. Disclosures:Chandra:Pharmion Corporation: Research Funding.