Resveratrol regulates cellular PKC alpha and delta to inhibit growth and induce apoptosis in gastric cancer cells

Resveratrol, a dietary phytoalexin, has emerged as a promising chemopreventive agent due to its antiproliferative and pro-apoptotic action toward cancer cells and its ability to inhibit tumor growth in animals. Gastric adenocarcinoma cells respond to resveratrol treatment with suppression of DNA synthesis, activation of nitric oxide synthase, induction of apoptosis and inhibition of total PKC and PKC alpha activity. Here we demonstrate that treatment of gastric adenocarcinoma SNU-1 cells with resveratrol results in time and concentration dependent accumulation of tumor suppressors p21(cip1/WAF-1) and p53 and is preceded by loss of membrane-associated PKC delta protein and a concomitant increase in cytosolic PKC alpha. Arrest of the cell cycle at transition of S to G(2)/M phases correlates with the profile of (3)H-thymidine incorporation and accumulation of p21(cip1/WAF-1) and was temporally dependent on increase of p53. SNU-1 cells respond to resveratrol treatment with up-regulation of both Fas and Fas-L proteins, whereas in KATO-III cells, with deleted p53, only Fas-L is increased after resveratrol treatment. Although Fas and Fas-L proteins in SNU-1 cells and Fas-L in KATO-III cells were elevated within 24 h of cell treatment with low concentrations of resveratrol, significant apoptotic response at these concentrations was observed only after 48 h. Altogether, our findings indicate that resveratrol engages PKC alpha and delta signals in gastric adenocarcinoma SNU-1 cells prior to up-regulation of antiproliferative and pro-apoptotic signals. The specific cell death signals engaged by resveratrol appear to be cell type dependent and suggest that resveratrol has chemopreventive potential even after mutational changes have occurred.

Overexpression of carbonic anhydrase-related protein XI promotes proliferation and invasion of gastrointestinal stromal tumors

Three isoforms of carbonic anhydrase-related protein (CA-RP) are evolutionally well conserved among the CA gene family but lack classical CA activity. Although the biological function of CA-RPs is unknown, overexpression of CA-RP VIII has been reported in certain tumor types. Based on the finding that CA-RPs are commonly expressed in the neuronal cells, we investigated expression of all three CA-RPs in gastrointestinal stromal tumor (GIST). In contrast to no detectable signal of any of the three CA-RPs in intestinal cells of Cajal, immunohistochemical analysis showed distinct cytoplasmic expressions of CA-RPs VIII and XI in 13 (59%) and 20 (91%) of 22 GIST tissue specimens, respectively. The positive signals for both CA-RPs VIII and XI were more intense in the periphery than in the central part of GISTs, whereas no significant signal for CA-RP X expression was observed in any of the GISTs. These expression patterns of CA-RPs were consistently observed by reverse transcription-polymerase chain reaction-Southern blot and immunocytochemistry in the cultured GIST cell line GIST-T1. Ectopic expression of CA-RP XI in GIST-T1 cells induced cell proliferation and invasion in vitro. These findings indicate that CA-RP XI plays a role in the development of GIST.

A simultaneous assessment of CYP3A4 metabolism and induction in the DPX-2 cell line

The DPX-2 cell line, a derivative of HepG2 cells, harbors human PXR and a luciferase-linked CYP3A4 promoter. These cells were used in a panel of cell-based assays for a parallel assessment of CYP3A4 induction, metabolism, and inhibition at the cellular level. CYP3A4 induction in the DPX-2 cell line by various agents was monitored in 96-well plates by a luciferase-based transcriptional activation assay. Of the prototypical CYP3A4 inducers examined, all exhibited elevated luciferase activity in DPX-2 cells. CYP3A4 enzyme activity in noninduced and rifampicin-induced DPX-2 cells was also assessed using Vivid fluorogenic substrates. Significantly elevated CYP3A4 activity levels (2.8-fold +/- 0.2-fold above DMSO-treated cells) were found in DPX-2 cells after 48 hours of exposure to rifampicin, but were undetectable in parental HepG2 cells. Rifampicin-induced activity levels were found to be suitable for assessing the inhibitory potential of new chemical entities in downstream CYP3A4 inhibition assays. The elevated CYP3A4 activity was inhibited 85% by 10 microM ketoconazole. In addition, a cytotoxicity assay to correct for possible toxic effects of compounds at the cellular level was applied. The comparative data obtained with a combination of the above assays suggests that the application of several independent in vitro technologies used in DPX-2 cells is the best possible strategy for the assessment of the complex phenomena of CYP3A4 induction and inhibition.

Subtype selective interactions of somatostatin and somatostatin analogs with sst1, sst2, and sst5 in BON-1 cells

Somatostatin is a polypeptide hormone acting as an inhibitor of pituitary, pancreatic, and gastrointestinal secretion through specific membrane receptors of which five subtypes have been cloned (sst(1-5)). Somatostatin analogs are used in the clinic to treat patients with excessive hormone production due to a neuroendocrine tumor. The aim of this study was to investigate the biological activity of three new somatostatin receptor subtype selective analogs (BIM-23926, sst(1)-selective; BIM-23120, sst(2)-selective; and BIM-23206, sst(5)-selective) in the human neuroendocrine tumor cell line, BON-1, which expresses sst(1), sst(2), and sst(5) natively. Somatostatin-14 and octreotide were used as reference substances. Forskolin-induced cAMP accumulation and chromogranin A (CgA) secretion were inhibited by BIM-23120, BIM-23206, and somatostatin-14 in a dose-dependent manner. Cholecystokinin (CCK-8) stimulated activation of mitogen-activated protein (MAP) kinase was inhibited by BIM-23120 and BIM-23206, while BIM-23926 stimulated the activity. Selective BIM analogs showed a more efficient inhibitory effect on cAMP accumulation, CgA secretion, and MAP kinase activity than octreotide in BON-1 cells. This may be explained by the differences in affinity of the ligand to the receptor or by interaction between different sst subtypes. We conclude that increasing knowledge about sst physiology and expression in malignant disease indicates a need for new analogs that can be incorporated into the therapeutic arsenal.

15-Hydroxyprostaglandin dehydrogenase can be induced by dexamethasone and other glucocorticoids at the therapeutic level in A549 human lung adenocarcinoma cells

Dexamethasone induced the expression of 15-PGDH in a time- and concentration-dependent manner in A549 human lung adenocarcinoma cells. Maximal induction was observed at 10nM. Induction of 15-PGDH expression was also achieved by other synthetic glucocorticoids. Induction was inhibited by the addition of pro-inflammatory cytokines and phorbol ester. These pro-inflammatory agents were also shown to induce COX-2 expression. PMA was found to be the most effective stimulator of COX-2 expression and the most potent inhibitor of dexamethasone-induced 15-PGDH expression. Attenuation of dexamethasone-induced 15-PGDH expression by PMA was, in part, due to a protein kinase C-mediated mechanism. The induction of 15-PGDH expression by dexamethasone was blocked by a glucocorticoid receptor antagonist RU 486 and by a nuclear translocation inhibitor geldanamycin, indicating that the induction is a genetic mechanism. The induction of 15-PGDH expression by dexamethasone and other glucocorticoids at the therapeutic level provides an additional biochemical mechanism for the anti-inflammatory action of these glucocorticoids.

Improvement in biocompatibility of ZrO2–Al2O3 nano-composite by addition of HA

The biocompatibility of zirconia-alumina (ZA) nano-composites in load-bearing applications such as dental/orthopedic implants was significantly enhanced by the addition of bioactive HA. The ZA matrix was composed of nano-composite powder obtained from the Pechini process and had higher flexural strength than conventionally mixed zirconia-alumina composite. Because the ZA nano-composite powder effectively decreased the contact area between HA and zirconia for their reaction during the sintering process, the HA-added ZA nano-composites contained biphasic calcium phosphates (BCP) of HA/TCP and had higher flexural strength than conventionally mixed ZA-HA composite. From the in vitro test with osteoblastic cell-lines, the proliferation and the differentiation (as expressed by the alkaline phosphatase activity) of the cellular response on the HA-added ZA nano-composites gradually increased as the amount of HA added increased. From the mechanical and biological evaluations of the HA-added ZA nano-composites, 30HA (30 vol% HA + 70 vol% ZA) was found to be the optimal composition for load-bearing biological applications.

Nitrofen induces a redox-dependent apoptosis associated with increased p38 activity in P19 teratocarcinoma cells

Nitrofen is a diphenyl ether herbicide that produces a spectrum of fetal abnormalities in rodents. To characterize the molecular mechanisms of nitrofen-mediated birth defects at the cellular level, we explored its effects on undifferentiated P19 teratocarcinoma cells. Nitrofen induces a time-dependent cell death of P19 cells that is associated with increases in TUNEL-positivity and caspase-3 cleavage suggesting that nitrofen induces P19 cell apoptosis. In addition, the increase in TUNEL-positive cells was inhibited with zVAD-fmk, suggesting that nitrofen induces a caspase-dependent apoptosis. Nitrofen treatment was associated with increased p38 MAP kinase activity, though pretreatment of cells with multiple p38 inhibitors did not affect nitrofen-mediated caspase-3 cleavage, suggesting caspase-3 cleavage is p38-independent. Nitrofen induced a dose-dependent increase in reactive oxygen species (ROS), which was accompanied by a decrease in the ratio of reduced/oxidized glutathione, indicating that nitrofen alters the cellular redox state of these cells. Furthermore, pretreatment of cells with N-acetyl cysteine gave a dose- and time-dependent reduction of caspase-3 cleavage, supporting the observations that caspase-3 cleavage is cell-redox-dependent. Therefore, nitrofen induces P19 cell apoptosis that is cell-redox-dependent and is associated with increases in p38 activity and ROS and may play a role in nitrofen-mediated birth defects.

Potencial anti-apoptótico de p38 en cáncer de próstata

INTRODUCTION

TNF-alpha transduction pathway in prostate cancer seems to be diverted towards p38 activation. P38 may protect prostate tumoral cells from TNF-alpha apoptosis induced. The aim of this study was study the role of p38 in vivo (were evaluated some p38 downstream factors), as well as in vitro (in prostatic tumoral cell lines, LNCaP and PC3, pre-treated with TNF-alpha).

MATERIAL AND METHODS

Two prostatic tumoral cell lines (LNCaP and PC3) were used in in vitro studies. Two different experiments were made: with TNF-alpha (several concentrations) and p38 specific inhibitor (SB203580). The apoptotic index were evaluated using DAPI staining and flow cytometry. P38 activation was measured by Western blot analysis. 15 normal samples (NP) and 27 prostate cancer samples (PC) were used in in vivo study, all of them were processed for immunohistochemistry and Western-blot.

RESULTS

In vitro, TNF-alpha induced apoptosis in LnCap when we increased its concentration but not in PC3. TNF-alpha stimulation led to increase a time-dependent p38 phosphorylation in two intermediate doses whereas in PC3 not changes were found. In LNCaP after its preincubation with SB203580 and TNF-alpha treatment showed a significative increasing of apoptosis. In vivo, all NP samples were found positives to p-Elk-1 and p-ATF-2 (nuclei of epithelial cells). In PC the expression of p-Elk-1 or p-ATF-2 increased and was located in the nucleus and cytoplasm of epithelial cells.

CONCLUSION

Our data in vitro and in vivo suggest that p38 plays a very important role in prostatic tumour progression. These data suggest that the control activation of p38 might be a possible target to cancer prostate treatment.

Histone deacetylase inhibitors interact synergistically with tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to induce apoptosis in carcinoma cell lines

Both tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and histone deacetylase inhibitors (HDIs) show promise for the treatment of cancer. However, in a number of reports they have been proven ineffective to induce cell death when applied as single agents. In this study, we show that A549 lung carcinoma cells and PC-3 prostate carcinoma cells underwent substantial apoptosis when coexposed to TRAIL and either suberoylanilide hydroxamic acid, sodium butyrate or trichostatin A. HDIs and TRAIL synergized in activation of capase-3, induction of internucleosomal DNA fragmentation and promoting mitochondrial damage. Significantly, cotreatment with minimally toxic doses of HDIs and TRAIL resulted in a marked apoptotic response in both cell lines. These data provide a rationale for a more in-depth exploration into the potential of combining TRAIL and HDIs as a valuable anticancer strategy.

[Effect of EGF on the activity of nuclear and cytoplasmic 26S proteasomes in A431 cells]

It has been first shown that EGF regulates a proteolytic activity of proteasomes. Following a 15 min action with 100 ng/ml EGF, three types of peptidase activity of both cytoplasmic and nuclear proteasomes were induced in A431 cells, although, this effect on different populations of proteasomes was selective. EGF preferentially stimulates chymotrypsin-like activity of cytoplasmic proteasomes, and induces a similar increase of chymotrypsin-like, trypsin-like and peptydylglutamyl peptide hydrolase activities of nuclear particles. Tyrphostin, an inhibitor of tyrosine kinase activity of EGF receptor, prevents the EGF effect on both proteolytic and RNase activity of nuclear and cytoplasmic proteasomes. It is concluded that EGF may rapidly and selectively stimulate enzymatic activity of EGF receptor.

Potentiality of DNA-dependent protein kinase to phosphorylate Ser46 of human p53

DNA damage induces accumulation and activation of p53 via various posttranslational modifications. Among them, several lines of evidence indicated the phosphorylation of Ser46 as an important mediator of DNA damage-induced apoptosis but the responsible kinase remains to be clarified, especially in the case of ionizing radiation (IR). Here we showed that DNA-dependent protein kinase (DNA-PK) could phosphorylate Ser46 of p53 in addition to reported phosphorylation sites Ser15 and Ser37. However, IR-induced phosphorylation of Ser46 was seen even in M059J, a human glioma cell line lacking DNA-PKcs, and it was, at most, only slightly less than in control M059K. On the other hand, a related kinase ataxia-telangiectasia mutated (ATM), which was shown to be essential for IR-induced phosphorylation of Ser46, could poorly phosphorylate Ser46 by itself. These results collectively suggested two pathways for IR-induced phosphorylation of Ser46, i.e., direct phosphorylation by DNA-PK and indirect phosphorylation via ATM.

Proteasome proteolytic activity in hematopoietic cells from patients with chronic myeloid leukemia and multiple myeloma

BACKGROUND AND OBJECTIVES

The proteasome is a multicatalytic complex found in all eukaryotic cells; it is responsible for the degradation of key regulatory proteins associated with the cell cycle and apoptosis. In vitro, proteasome inhibitors can induce selective apoptosis in some malignant cell types as opposed to in their normal counterparts and first generation compounds are currently in clinical trials for the treatment of multiple myeloma. The objective of our study was to develop a method to extract and measure functional proteasome activity in primary human cells so that this method could then be used to determine whether patients might benefit from proteasome inhibitor therapy.

DESIGN AND METHODS

Optimal proteasome extraction and assay conditions were established with myeloma and leukemic cell lines. These conditions were then applied to primary human cells from patients. Proteasome was extracted using lysis buffer and activity measured as turnover of a peptide fluorescent substrate.

RESULTS

Cells expressing bcr-abl showed significantly higher proteasome levels (372+/-16 AFU/1x10(6) cells/min) than did bcr-abl-negative cells (151+/- 8 AFU/1x10(6) cells/min) and were more sensitive to induction of apoptosis by proteasome inhibitor. Human myeloid leukemia cell lines showed higher levels of activity than those representing myeloma (eg HL-60 cells 947+/-25 AFU/1x10(6) cells/min; U266 177+/-6 AFU/1x10(6) cells/min). Primary cells from patients had similar levels of activity to those of the comparable cell line model.

INTERPRETATION AND CONCLUSIONS

This simple method measures functional proteasome activity in primary leukemic cells and demonstrates for the first time that this activity is higher in myeloid leukemia than in myeloma cells.

Suramin sensitizing cells to ionizing radiation by inactivating DNA-dependent protein kinase

Here we report that suramin sensitizes LM217, MDA-MB-468, T98G and A431 cells to ionizing radiation. Suramin sensitized cells to X radiation in a dose-dependent fashion, and longer exposure to suramin before X irradiation resulted in more efficient sensitization. The dose-modifying factors calculated from the survival curves were 1.18 in LM217 cells and 1.37 in MDA-MB-468 cells. Suramin did not sensitize Scid cells that had no DNA-dependent protein kinase activity. Suramin inhibited DNA-dependent protein kinase activity in vitro and in vivo. The concentration of suramin resulting in 50% inhibition in vitro was 1.7 microM in LM217 cells and 2.4 microM in MDA-MB-468 cells. Exposure of LM217 and MDA-MB-468 cells to suramin did not affect the level of Ku70 (G22P1) or Ku80 (XRCC5), but it increased the level of DNA-PKcs(PRKDC). Suramin did not sensitize LM217 or MDA-MB-468 cells to UV radiation. Suramin's effects were not caused by accumulation of cells in a specific phase of the cell cycle. These results suggest that suramin sensitizes cells to ionizing radiation by inhibiting DNA-dependent protein kinase activity.

Sp3 repression of polymorphic human NRH:quinone oxidoreductase 2 gene promoter

Human NRH:quinone oxidoreductase 2 (NQO2) gene-containing 29-bp deletion/insertion polymorphic promoters were found to be associated with susceptibility to Parkinson's disease. Here, we demonstrate that the NQO2 gene is differentially expressed by the polymorphic promoters in human fibroblasts and Hep-G2 cells transfected with NQO2 gene reporter constructs. Promoter containing the 29-bp insertion polymorphism demonstrated significantly lower NQO2 gene expression. Deletion mutagenesis and DNase I footprinting analysis of the promoter without the 29-bp insertion identified three protected regions (region A, B, and C). Band- and supershift and transfection assays showed binding of transcription factor Sp1 to regions A and B, which regulated expression of the NQO2 gene. Similar studies of the NQO2 gene promoter with the 29-bp insertion polymorphism showed that regions A and C were identical and contributed similarly as in the promoter without the 29-bp insertion to NQO2 gene expression. However, region B was found to be inserted with 29-bp DNA element and bound to both Sp1 and Sp3. Binding of Sp3 led to repression of NQO2 gene transcription by the promoter containing the 29-bp insertion polymorphism. These studies also suggest that alterations in NQO2 activity might be an important factor in susceptibility to Parkinson's disease.

Localization of heparanase in esophageal cancer cells: respective roles in prognosis and differentiation

In this study, we examined the distribution of heparanase protein in 75 esophageal squamous cell carcinomas by immunohistochemistry and analyzed the relationship between heparanase expression and clinicopathological characteristics. In situ hybridization showed that the mRNA expression pattern of heparanase was similar to that of the protein, suggesting that increased expression of the heparanase protein at the invasive front was caused by an increase of heparanase mRNA in tumor cells. Heparanase expression correlated significantly with depth of tumor invasion, lymph node metastasis, tumor node metastasis (TNM) stage and lymphatic invasion. Overexpression of heparanase in esophageal cancers was also associated with poor survival. In addition to its localization in the cytoplasm and cell membrane, heparanase was also identified in the nuclei of normal epithelial and tumor cells by immunohistochemistry. Furthermore, nuclear heparanase was detected in nuclear extract of cancer cell lines by Western blot and immunohistochemistry. Examination of the role of nuclear heparanase in cell proliferation and differentiation by double immunostaining for proliferating cell nuclear antigen (PCNA) and cytokeratin 10 (CK10) showed significant relationship between nuclear heparanase expression and differentiation (heparanase vs CK10), but not for proliferative state of esophageal cancer cells (heparanase vs PCNA). Our results suggest that cytoplasmic heparanase appears to be a useful prognostic marker in patients with esophageal cancer and that nuclear heparanase protein may play a role in differentiation. Inhibition of heparanase activity may be effective in the control of esophageal tumor invasion and metastasis.

Proteasome Inhibition Sensitizes Non–Small-Cell Lung Cancer to Gemcitabine-Induced Apoptosis

BACKGROUND

My colleagues and I have previously shown that chemotherapy activates the antiapoptotic transcription factor nuclear factor (NF)-kappaB in non-small-cell lung cancer (NSCLC). We hypothesized that inhibition of NF-kappaB by using the proteasome inhibitor bortezomib (Velcade) would sensitize NSCLC to gemcitabine-induced apoptosis.

METHODS

Tumorigenic NSCLC cell lines (H157 and A549) were treated with nothing, gemcitabine, bortezomib, or both compounds. NF-kappaB activity was determined by nuclear p65 protein levels, electrophoretic mobility shift assays, and reverse transcription-polymerase chain reaction of the NF-kappaB-regulated genes interleukin-8, c-IAP2, and Bcl-xL. The p21 and p53 protein levels were determined in similarly treated cells. Cell-cycle dysregulation was assessed by fluorescence-activated cell sorting analysis. Cell death and apoptosis were quantified by clonogenic assays, caspase-3 activation, and DNA fragmentation. NSCLC A549 xenografts were generated and treated as noted previously. Tumor growth was assessed over a 4-week treatment period. Statistical analysis was performed with analysis of variance.

RESULTS

Gemcitabine enhanced nuclear p65 levels, NF-kappaB binding to DNA, and transcription of all NF-kappaB-regulated genes. Bortezomib inhibited each of these effects. Combined gemcitabine and bortezomib enhanced p21 and p53 expression and induced S-phase and G2/M cell-cycle arrests, respectively. Combined treatment killed 80% of the NSCLC cells and induced apoptosis, as determined by caspase-3 activation (p = 0.05) and DNA fragmentation (p = 0.02). NSCLC xenografts treated with combination therapy grew significantly slower than xenografts treated with gemcitabine alone (p = 0.02).

CONCLUSIONS

Bortezomib inhibits gemcitabine-induced activation of NF-kappaB and sensitizes NSCLC to death in vitro and in vivo. This combined treatment strategy warrants further investigation and may represent a reasonable treatment strategy for select patients with NSCLC given the current clinical availability of both drugs.

Regulation of STAT3 by mu-opioid receptors in human neuroblastoma SH-SY5Y cells

Heptahelical opioid receptors are implicated in the transcriptional regulation of neuronal development. Here we demonstrated that activation of mu-opioid receptors in human neuroblastoma SH-SY5Y cells led to the activation of signal transducer and activator of transcription 3 (STAT3), a transcription factor central to the regulation of numerous biological processes. The mu-opioid-induced activation of STAT3 is sensitive to receptor was further shown to pertussis toxin treatment and required JAK and Src tyrosine kinases, but not phosphatidylinositol 3-kinase. This mu-opioid-induced response was mediated via the extracellular signal-regulated protein kinase in a Raf-1-independent manner. The present study provides a foundation to explore the importance of STAT3 signaling in the regulation of neuronal growth and differentiation by the mu-opioid receptor.

Induction and inhibition of aromatase (CYP19) activity by natural and synthetic flavonoid compounds in H295R human adrenocortical carcinoma cells

Flavonoids and related structures (e.g., flavones, isoflavones, flavanones, catechins) exert various biological effects, including anticarcinogenic, antioxidant and (anti-)estrogenic effects, and modulation of sex hormone homeostasis. A key enzyme in the synthesis of estrogens from androgens is aromatase (cytochrome P450 19; CYP19). We investigated the effects of various natural and synthetic flavonoids on the catalytic activity and promoter-specific expression of aromatase in H295R human adrenocortical carcinoma cells. Natural flavones were consistently more potent inhibitors than flavanones. IC(50) values for 7-hydroxyflavone, chrysin, and apigenin were 4, 7, and 20 microM, respectively; for the flavanones 7-hydroxyflavanone and naringenin the IC(50) values were 65 and 85 microM, respectively. The steroidal aromatase inhibitor (positive control) 4-hydroxyandrostenedione had an IC(50) of 20 nM. The inhibition by apigenin and naringenin coincided with some degree of cytotoxicity at 100 microM. The natural flavonoid derivative rotenone (IC(50) 0.3 microM) was the most potent aromatase inhibitor tested. Several synthetic flavonoid and structurally related quinolin-4-one analogs inhibited aromatase activity. The most potent inhibitor was 4'-tert-butyl-quinolin-4-one (IC(50) 2 microM), followed by two 2-pyridinyl-substituted alpha-naphthoflavones (IC(50)s 5 and >30 microM). The two 2-pyridinyl-substituted gamma-naphthoflavones consistently produced biphasic concentration-response curves, causing about 1.5-fold aromatase induction at concentrations below 1 microM and inhibition above that level (IC(50)s 7 and >30 microM). The natural flavone quercetin and isoflavone genistein induced aromatase activity 4- and 2.5-fold induction, respectively, at 10 microM. This coincided with increased intracellular cAMP concentrations and increased levels of the cAMP-dependent pII and to a lesser extent 1.3 promoter-specific aromatase transcripts. These results shed light on the structure-activity relationships for aromatase inhibition as well as mechanisms of induction in human H295R cells.

Inhibition and mechanism of action of a protease inhibitor in human pancreatic cancer cells

OBJECTIVES

Tumor-associated trypsinogen (TAT), urokinase-type plasminogen activator (u-PA), matrix metalloproteinase-2 (MMP-2), and MMP-9 each play a dominant role in the degradation of extracellular matrix (ECM) during the invasion process of pancreatic cancer. Transforming growth factor beta1 (TGF-beta1) is a multifunctional poly-peptide that regulates cell growth and differentiation, ECM deposition, cellular adhesion properties, angiogenesis, and also immune functions. We previously reported that TGF-beta1 up-regulated vascular endothelial growth factor (VEGF) production and protease production of MMP-2 and of u-PA in the highly metastatic pancreatic cancer cell lines SW1990 and CAPAN-2. In this study, we examined the inhibitor effects of a protease inhibitor, gabexate mesilate (GM), on cell invasion, cell proliferation, growth factor production, and ECM degradation. We also examined the effect of GM on the production of growth factor and ECM degradation by these cell proteases and enzymatic activities.

RESULTS

GM down-regulated the invasiveness and liver metastasis potential of SW1990 and CAPAN-2 cells, but it did not affect the proliferation of these cells. GM inhibited not only the enzymatic activities of TAT and u-PA but also the production of MMP-2, and u-PA, all of which have been known to be secondarily down-regulated by TGF-beta1.

CONCLUSIONS

These findings suggested that GM has very good potential for use in the treatment against invasion and metastasis of pancreatic cancer.

The influence of platelets on the promotion of invasion by tumor cells and inhibition by antiplatelet agents

OBJECTIVE

Using a chemoinvasion assay, we show that platelets promote invasiveness of 5 pancreatic adenocarcinoma cell lines.

METHODS

Gelatin zymography and Western blot analysis were performed to detect metalloproteinase-9 (MMP-9) secreted from tumor cells in the presence or absence of platelets. The effects of antiplatelet agents on the invasiveness of tumor cells and the secretion level of MMP-9 were evaluated.

RESULTS

The number of traversed tumor cells significantly increased when incubated with platelets compared without platelets in all cell lines. The MMP-9 band was detected in all tumor cell lines, and the intensity was obviously greater in conditions of incubation with platelets than without. In the experiment of antiplatelet agents effects, it was confirmed that invasiveness of tumor cells significantly decreased following incubation with cilostazol depending on the concentration in spite of the presence of platelets. The level of MMP-9 also significantly decreased in the ELISA analysis.

CONCLUSIONS

These data mean platelets activate invasiveness of tumor cells because of enhanced MMP-9 secretion. Furthermore, anti-platelet drugs may inhibit invasiveness of tumor cells due to decreased MMP-9 secretion, and this inhibition may lead to the suppression of tumor cell invasion. We propose that antiplatelet agents are applicable in clinical treatment to inhibit metastasis of malignant tumor cells.

Endogenous Expression of Activation-Induced Cytidine Deaminase in Cell Line WEHI-231

Because of its susceptibility to apoptosis on Ag receptor cross-linking, cells of the mouse cell line WEHI-231 have been classified as immature B cells. Surprisingly, however, the cell line expresses activation-induced cytidine deaminase, the enzyme that mediates hypermutation and Ig class switch recombination in activated B cells. Although both cDNA sequence and protein expression of activation-induced cytidine deaminase appear normal, the cell line does not hypermutate an indicator plasmid. For the readout, the indicator plasmid depends on the removal of deoxyuridine after transition from C to U and, therefore, on functional expression of uracil N-glycosylase 2, which is normal in WEHI-231. At the endogenous Ig locus, however, WEHI-231 does undergo the canonical hypermutation of G. C to A. T base pairs to some extent. The cell line also expresses the germline transcripts of the Ig gamma 2b, epsilon, and alpha loci, but it does not switch its IgM surface Ig.

N-cyclohexanecarbonylpentadecylamine: a selective inhibitor of the acid amidase hydrolysing N-acylethanolamines, as a tool to distinguish acid amidase from fatty acid amide hydrolase

Anandamide ( N-arachidonoylethanolamine) and other bioactive N-acylethanolamines are degraded to their corresponding fatty acids and ethanolamine. This hydrolysis is mostly attributed to catalysis by FAAH (fatty acid amide hydrolase), which exhibits an alkaline pH optimum. In addition, we have identified another amidase which catalyses the same reaction exclusively at acidic pH values [Ueda, Yamanaka and Yamamoto (2001) J. Biol. Chem. 276, 35552-35557]. In attempts to find selective inhibitors of this acid amidase, we screened various derivatives of palmitic acid, 1-hexadecanol, and 1-pentadecylamine with N-palmitoylethanolamine as substrate. Here we show that N-cyclohexanecarbonylpentadecylamine inhibits the acid amidase from rat lung with an IC50 of 4.5 microM, without inhibiting FAAH at concentrations up to 100 microM. The inhibition was reversible and non-competitive. This compound also inhibited the acid amidase in intact alveolar macrophages. With the aid of this inhibitor, it was revealed that rat basophilic leukaemia cells possess the acid amidase as well as FAAH. Thus the inhibitor may be a useful tool to distinguish the acid amidase from FAAH in various tissues and cells and to elucidate the physiological role of the enzyme.

Involvement of Protein Kinase C-Related Anti-apoptosis Signaling in Radiation-Induced Apoptosis in Murine Thymic Lymphoma(3SBH5) Cells

Protein kinase C (PKC; also known as PRKC) is known to be an important participant in radiation-induced apoptosis. However, its role is not fully clarified. Using 3SBH5 cells, which are radiation-sensitive thymic lymphoma cells, the involvement and functions of PKC were assessed in radiation- induced apoptosis. PMA (phorbol 12-myristate 13-acetate), a PKC activator, inhibited the radiation-induced apoptosis in 3SBH5 cells. On the other hand, chelerythrine, a PKC inhibitor, potentiated apoptosis. In addition, Gö6976, a classical PKC (cPKC) inhibitor, which specifically inhibits PKC (alpha and betaI), also promoted apoptosis. Interestingly, post-treatment (20 min after irradiation) with Gö6976 had no effect on the radiation-induced apoptosis. These results suggest that cPKC is activated early after irradiation for anti-apoptosis signaling and contributes to the balance between cell survival and death. Indeed, an increase of cPKC activity involving PKC (alpha, betaI and betaII) was observed in the cytosolic fraction 3 min after irradiation with 0.5 Gy. However, no translocation of cPKC was observed in the cells after irradiation. Our findings indicate that activation of cPKC (alpha or beta) soon after irradiation is critical to the understanding of the regulation of radiation-induced apoptosis in radiation-sensitive cells.

Silibinin down-regulates prostate epithelium-derived Ets transcription factor in LNCaP prostate cancer cells

The androgen-sensitive human prostate cancer cell line LNCaP expresses the estrogen receptor beta and androgen receptor and can be stimulated by androgens to secrete prostate-specific antigen (PSA). In this study we demonstrate the cancer protective potential of silibinin, a flavolignan derived from the fruits of Silybum marianum, which down-regulates the co-activator of the androgen receptor, the prostate epithelium-derived Ets transcription factor (PDEF) and consequently the secretion of PSA. LNCaP cells were treated with various concentrations of silibinin in the presence or in the absence of 5alpha-dihydrotestosterone (DHT). We used real-time RT-PCR to quantify mRNA expression of PDEF and PSA with gene-specific dual-labelled fluorescence probes. PSA secretion from LNCaP cells in conditioned media was measured with the Elecsys System 2010. Silibinin down-regulated PSA mRNA expression and PSA secretion in conditioned medium under basal and DHT (10(-8) M) stimulated conditions, which was paralleled by PDEF down-regulation. DHT alone stimulated PDEF and PSA gene expression and PSA secretion. The down-regulation of basal as well as DHT stimulated PDEF and PSA by silibinin demonstrates the antiproliferative potential of this agent. These effects underline the possible therapeutic use of silibinin in the management of prostate cancer.

Quaternary benzo[c]phenanthridine alkaloids as inhibitors of dipeptidyl peptidase IV-like activity baring enzymes in human blood plasma and glioma cell lines

Quaternary benzo[c]phenanthridine alkaloids (QBA), fagaronine (FA), sanguinarine (SA), chelerythrine (CHE) and the QBA extract from Macleya cordata (EX) exerted differential inhibitory effect on the hydrolytic activity of particular dipeptidyl peptidase (DPP)-like enzyme isolated from human blood plasma and from human and rat glioma cell lines. The low-MW form of DPP-IV-like enzyme activity, corresponding most probably to DPP-8, observed only in glioma cells but not in human plasma, was inhibited preferentially by SA, CHE and EX, and only slightly by FA. The alkaloid inhibitory effect was concentration-dependent in the range 25-150 mM and directly pH-related. In addition, a subtle but consistent inhibition of the intermediate-MW form of DPP-IV-like enzyme activity, ascribed to DPP-IV/CD26, observed only in human plasma and of the attractin (high-MW form of DPP-IV-like enzyme activity, expressed in U87 glioma cells) by the studied alkaloids was observed. We conclude that some of the QBA biological effects could be determined by tissue and cell type specific dipeptidyl peptidase IV-like molecules expression pattern.

c-Jun N-terminal kinase is required for vitamin E succinate-induced apoptosis in human gastric cancer cells

AIM: To investigate the roles of c-Jun N-terminal kinase (JNK) signaling pathway in vitamin E succinate-induced apoptosis in human gastric cancer SGC-7901 cells.

METHODS: Human gastric cancer cell lines (SGC-7901) were treated with vitamin E succinate (VES) at 5, 10, 20 mg/L. Succinic acid and vitamin E were used as vehicle controls and condition medium only as an untreated (UT) control. Apoptosis was observed by 4’, 6-diamidine-2’-phenylindole dihydrochloride (DAPI) staining for morphological changes and by DNA fragmentation for biochemical alterations. Western blot analysis was applied to measure the expression of JNK and phosphorylated JNK. After the cells were transiently transfected with dominant negative mutant of JNK (DN-JNK) followed by treatment of VES, the expression of JNK and c-Jun protein was determined.

RESULTS: The apoptotic changes were observed after VES treatment by DNA fragmentation. DNA ladder in the 20 mg/L VES group was more clearly seen than that in 10 mg/L VES group and was not detected following treatment of UT control, succinate and vitamin E. VES at 5, 10 and 20 mg/L increased the expression of p-JNK by 2.5-, 2.8- and 4.2-fold, respectively. VES induced the phosphorylation of JNK beginning at 1.5 h and produced a sustained increase for 24 h with the peak level at 12 h. Transient transfection of DN-JNK blocked VES-triggered apoptosis by 52%. DN-JNK significantly increased the level of JNK, while decreasing the expression of VES-induced c-Jun protein.

CONCLUSION: VES-induced apoptosis in human gastric cancer SGC-7901 cells involves JNK signaling pathway via c-Jun and its downstream transcription factor.

In vitro induction of differentiation by ginsenoside Rh2 in SMMC-7721 hepatocarcinoma cell line

The aim of this study was to investigate the effects of ginsenoside Rh(2) (G-Rh(2)) on differentiation of SMMC-7721 hepatocarcinoma cell line in culture. We studied G-Rh(2)-induced differentiation of SMMC-7721 cells through cell proliferation, cell morphology, ultrastructure, cell cycle, cell function and metabolism. The proliferation of treated cells was inhibited, the morphology and ultrastructure seemed normal, the secretory amount and expression of alpha-foetoprotein, and the specific activity of gamma-glutamyl transpeptidase, and heat-resistant alkaline phosphatase were all significantly decreased, the secretory amount of albumin and alkaline phosphatase activity were remarkably increased, and the cell was arrested at the G(1)/G(0) phase. Furthermore, G-Rh(2) induced elevated expression of the cyclin-dependent kinase inhibitor p21(WAF1) and p16(INK4a), and declined expressions of cyclin D1 and cyclin E. In addition, G-Rh(2) almost completely inhibited telomerase activity, as measured by polymerase chain reaction-based telomeric repeat amplification protocol coupled with enzyme-linked immune sorbent assay, and human telomerase reverse transcriptase mRNA. Based on these data, it is suggested that G-Rh(2) could induce cell differentiation tending to normal and effectively reduce telomerase activity with affecting transcription levels of human telomerase reverse transcriptase, paralleling the induction of cell differentiation.

A novel DNA topoisomerase inhibitor: dehydroebriconic acid, one of the lanostane-type triterpene acids from Poria cocos

Traditional Chinese medicinal plants are a treasure house for screening novel inhibitors of DNA polymerases and DNA topoisomerases from mammals; in the present study, nine lanostane-type triterpene acids were found in sclerotium of Poria cocos. Among the nine compounds, only dehydroebriconic acid could potently inhibit DNA topoisomerase II (topo II) activity (IC(50) = 4.6 microM), while the compound moderately inhibited the activities of DNA polymerases alpha, beta, gamma, delta, epsilon, eta, iota, kappa and lambda only from mammals, to similar extents. Another compound, dehydrotrametenonic acid, also showed moderate inhibitory effects against topo II (IC(50) = 37.5 microM) and weak effects against all the polymerases tested. Both compounds showed no inhibitory effect against topo I, higher plant (cauliflower) DNA polymerase I (alpha-like polymerase) or II (beta-like polymerase), calf thymus terminal deoxynucleotidyl transferase, human immunodeficiency virus type-1 reverse transcriptase, prokaryotic DNA polymerases such as the Klenow fragment of E. coli DNA polymerase I, Taq DNA polymerase and T4 DNA polymerase, or DNA metabolic enzymes such as T 7 RNA polymerase, T4 polynucleotide kinase and bovine deoxyribonuclease I. These findings suggest that dehydroebriconic acid and dehydrotrametenonic acid should be designated as topo II-preferential inhibitors, although they also moderately inhibited all the mammalian DNA polymerases tested. Both dehydrotrametenonic acid and dehydroebriconic acid could prevent the growth of human gastric cancer cells, and their LD(50) values were 63.6 and 38.4 microM, respectively. The cells were halted at the G1 phase in the cell cycle. The relation between the structure of triterpene acids and their inhibitory activities is discussed.

Functional role of matrix metalloproteinases in ovarian tumor cell plasticity

OBJECTIVE

We previously demonstrated that aggressive ovarian cancer cells are able to display in vitro vasculogenic mimicry, which is reflected by their ability to form vasculogenic-like networks in 3-dimensional cultures and to express vascular cell-associated markers. The goal of this study was to examine the functional role of specific matrix metalloproteinases in the formation of vasculogenic-like networks and extracellular matrix remodeling in vitro. We also investigated the clinical relevance of matrix metalloproteinase-2 and -9 and membrane type 1-matrix metalloproteinase in human ovarian cancers with evidence of tumor cell-lined vasculature.

STUDY DESIGN

Ovarian cancer cells (A2780-PAR, SKOV3, and EG) were seeded onto separate 3-dimensional cultures that contained either Matrigel or type I collagen, in the absence of endothelial cells or fibroblasts. These cultures were treated with either chemically modified tetracycline-3 (general matrix metalloproteinase inhibitor), recombinant tissue inhibitor of metalloproteinase-1 or -2, or function-blocking antibodies to matrix metalloproteinase-2 or -9 or membrane type 1-matrix metalloproteinase. In addition, 78 invasive epithelial ovarian cancers were evaluated for expression of matrix metalloproteinase-2 and -9 and membrane type 1-matrix metalloproteinase and correlated with various clinical parameters.

RESULTS

The aggressive ovarian cancer cells (SKOV3 and EG) were able to form in vitro vasculogenic-like networks and contract 3-dimensional collagen I gels, whereas the poorly aggressive A2780-PAR cell line did not. Chemically modified tetracycline-3 completely blocked the network formation. Blocking antibodies to matrix metalloproteinase-2 and membrane type 1-matrix metalloproteinase inhibited the formation of the vasculogenic-like networks and collagen gel contraction, but the antibody to matrix metalloproteinase-9 had no effect on network formation and minimal effect on gel contraction. Treatment of 3-dimensional cultures with tissue inhibitor of metalloproteinase-2 retarded the network formation and only small, partially developed structures were noted that did not form network connections. Tissue inhibitor of metalloproteinase-1 had no appreciable effect on the extent or efficiency of network formation. Human invasive ovarian cancers with evidence of tumor cell-lined vasculature were significantly more likely to have strong epithelial and stromal matrix metalloproteinase-2 and -9 and membrane type 1-matrix metalloproteinase expression (all probability values were <.05).

CONCLUSION

Matrix metalloproteinase-2 and membrane type 1-matrix metalloproteinase appear to play a key role in the development of vasculogenic-like networks and matrix remodeling by aggressive ovarian cancer cells. Human ovarian cancers with matrix metalloproteinase overexpression are more likely to have tumor cell-lined vasculature. These results may offer new insights for consideration in ovarian cancer treatment strategies.

Interferon-gamma induces caspase-8 in neuroblastomas without affecting methylation of caspase-8 promoter

BACKGROUND

The expression of caspase-8, a cysteine protease that is crucial for the apoptotic cascade, is absent in a high percentage of neuroblastomas, the most frequent extracranial solid tumor of infants and children. Resistance of neuroblastomas to death-receptor (eg, tumor necrosis factor alpha (TNF-alpha) receptor)--mediated apoptosis is thought to be caused by loss of caspase-8 expression. Gene silencing by hypermethylation of caspase-8 promoter has been proposed for the loss of caspase-8 expression in neuroblastoma cells.

METHODS

To further evaluate the role of caspase-8 in neuroblastoma, we assessed the induction of caspase-8 expression in neuroblastoma cells by treating the cells with a physiologic agent such as interferon-gamma.

RESULTS

The authors found that interferon-gamma induces caspase-8 expression in neuroblastoma cells irrespective of the gene silenced by hypermethylation of caspase-8 promoter. The authors show that interferon-gamma also regulates other apoptosis related gene expression. Moreover, they show that interferon-gamma treatment in combination with TNF-alpha decreases neuroblastoma cell proliferation.

CONCLUSIONS

Interferon-gamma induces procaspase-8 expression in neuroblastoma cells, and this induction is not dependent on demethylation of the caspase-8 promoter. Therapies aimed at inducing caspase-8 expression by adjunctive treatment, such as interferon-gamma, may increase the effectiveness of current chemotherapeutic regimens.

Effects of regulatory domains of specific isoforms of protein kinase C on growth control and apoptosis in MCF-7 breast cancer cells

Protein kinase C (PKC) is a multigene family consisting of at least 11 isoforms that play key roles in growth control and tumorigenesis. To understand the roles of specific isoforms of PKC in breast cancer, we generated derivatives of the human breast cancer cell line MCF-7 that stably overexpress dominant negative mutants (REG) of PKC-alpha, -epsilon, or -zeta, which encode only the regulatory domains of the respective isoforms. When stimulated to re-enter the cell cycle after serum starvation, the MCF-7/PKC-alpha-REG cell line exhibited enhanced cell-cycle progression in comparison to the control cell line. These cells also showed increased sensitivity to growth inhibition and induction of apoptosis in response to various cytotoxic stimuli, including serum starvation, tamoxifen, and gamma-radiation. Western blot analysis indicated that the MCF-7/PKC-alpha-REG cell line displayed marked decreases in the levels of the cyclin-dependent kinase inhibitor p21CIP1 and the anti-apoptotic protein bcl-2. Similar, but less striking, effects were seen in the MCF-7/PKC-epsilon-REG cell line, and the MCF-7/PKC-zeta-REG cell line showed minimal changes, when compared to the control cells. Taken together, these results suggest that the endogenous PKC-alpha in MCF-7 cells plays a critical role in regulating cell-cycle control and apoptosis, in part through upregulating the expression of p21CIP1 and bcl-2. Therefore, inhibitors of PKC-alpha may potentiate the activity of cytotoxic agents in the therapy of breast cancer.

In vitro inhibition of diacylglycerol acyltransferase by prenylflavonoids from Sophora flavescens

Four prenylflavonoids, kurarinone ( 1), a chalcone of 1, kuraridin ( 2), kurarinol ( 3), kushenol H ( 4) and kushenol K ( 5) isolated from the roots of Sophora flavescens were investigated for their inhibitory effects on diacylglycerol acyltransferase (DGAT). The flavonoids inhibited DGAT activity in a dose-dependent manner with IC50 values of 10.9 microM ( 1), 9.8 microM ( 2), 8.6 microM ( 3), 142.0 microM ( 4) and 250 microM ( 5). The prenylflavonoids without C3-OH ( 1, 2, 3) showed stronger inhibition than those with C3-OH ( 4, 5). On the other hand, flavonoids without side chains (hesperetin, naringenin, quercetin and kaempferol) did not inhibit the enzyme activity at a final concentration of 800 microM. These data suggest that the lavandulyl side chain and the position of the hydroxy group are important for high DGAT inhibitory activity. Compound 1 also inhibited de novo synthesis of triacylglycerol (TG) in Raji cells.

Correlation of thymidylate synthase, thymidine phosphorylase and dihydropyrimidine dehydrogenase with sensitivity of gastrointestinal cancer cells to 5-fluorouracil and 5-fluoro-2’-deoxyuridine

AIM: To determine the expression levels of three metabolic enzymes of fluoropyrimidines: thymidylate synthase (TS), thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) in seven human gastrointestinal cancer cell lines, and to compare the enzyme levels with the sensitivity to 5-fluorouracil (5-FU) and 5-fluoro-2’-deoxyuridine (FdUrd).

METHODS: TS, TP and DPD mRNA levels were assessed by semi-quantitative RT-PCR, TP and DPD protein contents were measured by ELISA. Fifty percent inhibitory concentrations of growth (IC50), representing the sensitivity to drugs, were determined by MTT assay.

RESULTS: IC50 values ranged from 1.28 to 12.26 uM for 5-FU, and from 5.02 to 24.21 uM for FdUrd, respectively. Cell lines with lower DPD mRNA and protein levels tended to be more sensitive to 5-FU (P < 0.05), but neither TS nor TP correlated with 5-FU IC50 (P > 0.05). Only TS mRNA level was sharply related with FdUrd sensitivity (P < 0.05), but TP and DPD were not (P > 0.05). A correlation was found between mRNA and protein levels of DPD (P < 0.05), but not TP (P < 0.05).

CONCLUSION: DPD and TS enzyme levels may be useful indicators in predicting the antitumor activity of 5-FU or FdUrd, respectively.

BMP4 signaling induces senescence and modulates the oncogenic phenotype of A549 lung adenocarcinoma cells

Lung cancer is the most common visceral malignancy in males, with rapidly increasing incidence in females, and a devastatingly poor prognosis. Transforming growth factor (TGF)-beta has been shown to induce senescence in A549 lung cancer cells, and both TGF-beta and bone morphogenetic protein (BMP) 2 can suppress the transformed phenotype of A549 cells in vitro. We examined the effects of BMP4, another member of the TGF-beta superfamily, on specific oncogenic properties of A549 cancer cells. When A549 cancer cells were treated continuously with 100 ng/ml of BMP4, a senescent phenotype was observed after 2 wk of treatment. The BMP-treated cells appeared larger than untreated cells, grew more slowly, had more senescence-associated beta-galactosidase activity, and had less telomerase activity, as measured by the telomeric repeat amplification protocol assay. Invasion through Engelbreth Holm-Swarm matrix was inhibited in the senescent cell population. Senescent BMP4-treated cells had lower ERK activation, VEGF expression, and Bcl2 expression than wild-type cells, consistent with a less proliferative, less angiogenic phenotype with increased susceptibility to death by apoptosis. BMP4 treatment also resulted in sustained elevation of Smad1. In vivo xenograft studies in the flanks of nude mice confirmed that the BMP-treated cells were significantly less tumorigenic than untreated cells. Direct overexpression of Smad1 using adenoviral constructs resulted in cell death within 5 days. These studies suggest that BMP4 pathway signaling can induce senescence and thus negatively regulate the growth of A549 lung cancer cells.

A novel mechanism for imatinib mesylate-induced cell death of BCR-ABL-positive human leukemic cells: caspase-independent, necrosis-like programmed cell death mediated by serine protease activity

Caspase-independent programmed cell death can exhibit either an apoptosis-like or a necrosis-like morphology. The ABL kinase inhibitor, imatinib mesylate, has been reported to induce apoptosis of BCR-ABL-positive cells in a caspase-dependent fashion. We investigated whether caspases alone were the mediators of imatinib mesylate-induced cell death. In contrast to previous reports, we found that a broad caspase inhibitor, zVAD-fmk, failed to prevent the death of imatinib mesylate-treated BCR-ABL-positive human leukemic cells. Moreover, zVAD-fmk-preincubated, imatinib mesylate-treated cells exhibited a necrosis-like morphology characterized by cellular pyknosis, cytoplasmic vacuolization, and the absence of nuclear signs of apoptosis. These cells manifested a loss of the mitochondrial transmembrane potential, indicating the mitochondrial involvement in this caspase-independent necrosis. We excluded the participation of several mitochondrial factors possibly involved in caspase-independent cell death such as apoptosis-inducing factor, endonuclease G, and reactive oxygen species. However, we observed the mitochondrial release of the serine protease Omi/HtrA2 into the cytosol of the cells treated with imatinib mesylate or zVAD-fmk plus imatinib mesylate. Furthermore, serine protease inhibitors prevented the caspase-independent necrosis. Taken together, our results suggest that imatinib mesylate induces a caspase-independent, necrosis-like programmed cell death mediated by the serine protease activity of Omi/HtrA2.

Roles of PLC-γ2 and PKCα in TPA-induced apoptosis of gastric cancer cells

AIM: To investigate the roles of PLCγ2 and PKCα in TPA-induced apoptosis of gastric cancer cells.

METHODS: Human gastric cancer cell line MGC80-3 was used. Protein expression levels of PLCγ2 and PKCα were detected by Western blot. Protein localization of PLCγ2 and PKCα was shown by immunofluoscence analysis under laser-scanning confocal microscope. Apoptotic morphology was observed by DAPI fluorescence staining, and apoptotic index was counted among 1000 cells randomly.

RESULTS: Treatment of gastric cancer cells MGC80-3 with TPA not only up-regulated expression of PLC-γ2 protein, but also induced PLC-γ2 translocation from the cytoplasm to the nucleus. However, this process was not directly associated with apoptosis induction. Further investigation showed that PKCα translocation from the cytoplasm to the nucleus was correlated with initiation of apoptosis. To explore the inevitable linkage between PLC-γ2 and PKCα during apoptosis induction, PLC inhibitor U73122 was used to block PLC-γ2 translocation, in which neither stimulating PKCα translocation nor inducing apoptosis occurred in MGC80-3 cells. However, when U73122-treated cells were exposed to TPA, not only PLC-γ2, but also PKCα was redistributed. On the other hand, when cells were treated with PKC inhibitor alone, PLC-γ2 protein was still located in the cytoplasm. However, redistribution of PLC-γ2 protein occurred in the presence of TPA, no matter whether PKC inhibitor existed or not.

CONCLUSION: PLC-γ2 translocation is critical in transmitting TPA signal to its downstream molecule PKCα. As an effector, PKCα directly promotes apoptosis of MGC80-3 cells. Therefore, protein translocation of PLCγ2 and PKCα is critical event in the process of apoptosis induction.

Influence of cultured dermal fibroblasts on human melanoma cell proliferation, matrix metalloproteinase-2 (MMP-2) expression and invasion in vitro

The dermis is the main site of melanoma invasion. Matrix metalloproteinases (MMPs), especially MMP-2, produced by melanoma or surrounding stromal cells, are essential for the destruction of dermal extracellular matrix. Here, we examined how dermal fibroblasts influenced proliferation, MMP-2 secretion and invasion of human melanoma cell lines in vitro. Human melanoma cell lines M3 Da and M1Dor were cocultured with dermal fibroblasts under non-contact and contact conditions in order to assess both soluble and insoluble factors, respectively. Zymographic analysis showed that the levels of MMP-2 and TIMP-2 in melanoma cells were not altered in non-contact cocultures when compared with those in individual cultures. However, in contact cocultures, the expression of MMP-2 in membrane extracts was enhanced. Under our coculture conditions, dermal fibroblasts failed to upregulate melanoma cell invasion through a three-dimensional type I collagen matrix. Since stromal and cancer cell contacts have been shown to occur after disruption of the extracellular matrix, we hypothesized that fibroblasts may influence melanoma cell invasion after the beginning of tumor progression through the dermis.

Induction of apoptosis through the activation of SAPK/JNK followed by the expression of death receptor Fas in X-irradiated cells

A post-irradiation treatment of the human leukemia cell line MOLT-4 with the antioxidant Trolox attenuated caspase-3 dependent apoptosis. The increase in the p53 expression and SAPK/JNK activation after X irradiation was also inhibited by a Trolox treatment, but the expression of BCL-2 and BAX, which would occur downstream from p53, was not changed. Studies on the effects of the intracellular calcium chelator BAPTA-AM on the induction of apoptosis and the activation of SAPK/JNK and caspase-3 proved that the chelation of calcium merely delayed the onset of radiation-induced apoptosis and the activation of SAPK/JNK and caspase-3. When the effects of the protein synthesis inhibitor cycloheximde on the apoptotic signaling pathways, including the activation of caspase family proteins and SAPK/JNK, were investigated, the expression of death receptor Fas through SAPK/JNK activation was found to be required for radiation-induced apoptosis. Finally, the relationship between the amounts of DNA dsb and induction of apoptosis was examined by irradiating BrdU-incorporated cells. An increase in DNA dsb caused by BrdU was found, but the induction of apoptosis was not enhanced. From these data, we could get no positive evidence for DNA as a target of X-rays and p53 as an indispensable factor to induced apoptosis in X-irradiated MOLT-4 cells.

Induction of cell death of human osteogenic sarcoma cells by zoledronic acid resembles anoikis

The aim of this study was to investigate the cytotoxic activity of the third-generation nitrogen-containing bisphosphonate zoledronic acid (ZOL) as a single agent, and in combination with clinically relevant anticancer drugs, in a panel of human osteogenic sarcoma cell lines (HOS, BTK-143, MG-63, SJSA-1, G-292, and SAOS2). We found that ZOL, when used alone, reduced cell number in a dose- and time-dependent manner, due either to cell cycle arrest in S-phase or to the induction of apoptosis. In the sensitive HOS, BTK-143, and G-292 cell lines, genomic DNA fragmentation and morphological changes characteristic of apoptosis were evident, and cells became nonadherent. Induction of apoptosis in osteosarcoma cells by ZOL was associated with caspase activation. However, coaddition of the broad-spectrum caspase inhibitors, z-VAD-fmk, Boc-D-fmk, or the caspase-3-specific inhibitor z-DEVD fmk, failed to protect these cells from ZOL-induced apoptosis. Our data support a ZOL-specific induction of cell apoptosis that involves cell detachment (anoikis), and in which caspase activation occurs secondarily to, and is redundant as a mediator of cell death. The addition of geranylgeraniol, an intermediate of the mevalonate pathway, suppressed the ZOL-induced apoptosis, suggesting that the cytotoxic effects of ZOL in osteosarcoma cells were mediated by the mevalonate pathway. While treatment of osteosarcoma cells with the chemotherapeutic agents doxorubicin or etoposide decreased cell viability, combination of these agents with ZOL did not significantly augment apoptosis in any of the cell lines tested. These observations suggest that ZOL has direct effects on the proliferation and survival of osteosarcoma cells in vitro, which has implications for future therapy of osteosarcoma.

DNA topoisomerases I and II inhibitory activity of constituents isolated from Juglans mandshurica

Nine diarylheptanoids (1-9), one triterpene (10), one sesquiterpenoid (11), one naphthoquinone (12), four tetralones (13-16), one naphthalene carboxylic acid glucoside (17) and six naphthalenyl glycosides (18-23) were isolated from the roots of Juglans mandshurica Maximowicz (Juglandaceae), and their structures determined from the chemical and spectral data. Here, we report the inhibitory effects, on the DNA topoisomerases I and II activities, of all these compounds. Compounds 10 and 23 showed more potent inhibitory effects, on the DNA topoisomerases I and II (94.0 and 86.0% inhibitions at the concentration of 5 microg/mL, respectively), than the positive control compounds, camptothecin and etoposide.

Advanced lipid extraction method for the determination of the phospholipase D activity

Phospholipase D is a ubiquitous enzyme that plays an important role in various lipid mediated cellular signaling pathways and produces rare phospholipids, phosphatidylethanol or phosphatidylbutanol, instead of phosphatidic acid with unique catalytic activity transphosphatidylation in the presence of primary alcohols. The reaction products, phosphatidylethanol or phosphatidylbutanol are used as markers of in vitro phospholipase D activity in many studies. For the sensitive detection of the phospholipase D products, we developed an advanced lipid extraction method that facilitates recovery of the compounds. With the new method, the activity change of phospholipase D by agonists could be detected more easily and the recovery rate was also increased. The increase of detected enzyme activity change was about double fold compared to the conventional lipid extraction method. This method provides selective force for the phospholipase D products in the extraction procedure.

Antisense oligodeoxynucleotides directed against aspartyl (asparaginyl) beta-hydroxylase suppress migration of cholangiocarcinoma cells

BACKGROUND

Aspartyl (asparaginyl) beta-hydroxylase (AAH) is an alpha-ketoglutarate-dependent dioxygenase that hydroxylates aspartate and asparagine residues in EGF-like domains of proteins. The consensus sequence for AAH beta-hydroxylation occurs in signaling molecules such as Notch and Notch homologs, which have roles in cell migration.

AIM

This study evaluated the potential role of AAH in cell migration using cholangiocarcinoma cell lines as models due to their tendency to widely infiltrate the liver.

METHODS

Five human cholangiocarcinoma cell lines established from human tumors were examined for AAH expression and motility. The effect of antisense oligodeoxynucleotide inhibition of AAH on cholangiocarcinoma cell migration was investigated.

RESULTS

Western blot analysis detected the approximately 86 kDa AAH protein in all five cholangiocarcinoma cell lines, and higher levels of AAH in cell lines derived from moderately or poorly differentiated compared with well-differentiated tumors. Immunocytochemical staining and fluorescence activated cell sorting analysis revealed both surface and intracellular AAH immunoreactivity. Using the phagokinetic non-directional migration assay and a novel ATPLite luminescence-based directional migration assay, we correlated AAH expression with motility. Correspondingly, antisense and not sense or mutated antisense AAH oligodeoxynucleotides significantly inhibited AAH expression and motility in cholangiocarcinoma cells.

CONCLUSIONS

AAH over-expression may contribute to the infiltrative growth pattern of cholangiocarcinoma cells by promoting motility.

Alterations in cell membrane properties caused by perfluorinated compounds

The recent detection of perfluorinated compounds (PFCs) in wildlife from even remote locations has spurred interest in the environmental occurrence and effects of these chemicals. While the global distribution of PFCs is increasingly understood, there is still little information available on their effects on wildlife. The amphiphillic nature of PFCs suggests that their effects could be primarily on cell membranes. In this study we measured the effects of PFCs on membrane fluidity and mitochondrial membrane potential using flow cytometry and effects on membrane permeability using cell bioassay procedures (H4IIE, MCF-7, PLHC-1). Of the PFCs tested, only perfluorooctane sulfonic acid (PFOS) increased the permeability of cell membranes to the hydrophobic ligands used. Three PFCs were tested in the membrane fluidity assay: PFOS, perfluorohexane sulfonic acid (PFHS), and perfluorobutane sulfonic acid (PFBS). PFOS increased membrane fluidity in fish leukocytes in a dose-dependent fashion, while PFHS and PFBS had no effect in the concentration range tested. The lowest effective concentrations for the membrane fluidity effects of PFOS were 5-15 mg/l. Effects on mitochondrial membrane potential occurred in the same concentration range as effects on membrane fluidity. This suggests that PFOS effects membrane properties at concentrations below those associated with other adverse effects.

Activity and expression of progesterone metabolizing 5alpha-reductase, 20alpha-hydroxysteroid oxidoreductase and 3alpha(beta)-hydroxysteroid oxidoreductases in tumorigenic (MCF-7, MDA-MB-231, T-47D) and nontumorigenic (MCF-10A) human breast cancer cells

BACKGROUND

Recent observations indicate that human tumorous breast tissue metabolizes progesterone differently than nontumorous breast tissue. Specifically, 5alpha-reduced metabolites (5alpha-pregnanes, shown to stimulate cell proliferation and detachment) are produced at a significantly higher rate in tumorous tissue, indicating increased 5alpha-reductase (5alphaR) activity. Conversely, the activities of 3alpha-hydroxysteroid oxidoreductase (3alpha-HSO) and 20alpha-HSO enzymes appeared to be higher in normal tissues. The elevated conversion to 5alpha-pregnanes occurred regardless of estrogen (ER) or progesterone (PR) receptor levels. To gain insight into these differences, the activities and expression of these progesterone converting enzymes were investigated in a nontumorigenic cell line, MCF-10A (ER- and PR-negative), and the three tumorigenic cell lines, MDA-MB-231 (ER- and PR-negative), MCF-7 and T-47D (ER- and PR-positive).

METHODS

For the enzyme activity studies, either whole cells were incubated with [14C]progesterone for 2, 4, 8, and 24 hours, or the microsomal/cytosolic fraction was incubated for 15-60 minutes with [3H]progesterone, and the metabolites were identified and quantified. Semi-quantitative RT-PCR was employed to determine the relative levels of expression of 5alphaR type1 (SRD5A1), 5alphaR type 2 (SRD5A2), 20alpha-HSO (AKR1C1), 3alpha-HSO type 2 (AKR1C3), 3alpha-HSO type 3 (AKR1C2) and 3beta-HSO (HSD3B1/HSD3B2) in the four cell lines using 18S rRNA as an internal control.

RESULTS

The relative 5alpha-reductase activity, when considered as a ratio of 5alpha-pregnanes/4-pregnenes, was 4.21 (+/- 0.49) for MCF-7 cells, 6.24 (+/- 1.14) for MDA-MB-231 cells, 4.62 (+/- 0.43) for T-47D cells and 0.65 (+/- 0.07) for MCF-10A cells, constituting approximately 6.5-fold, 9.6-fold and 7.1 fold higher conversion to 5alpha-pregnanes in the tumorigenic cells, respectively, than in the nontumorigenic MCF-10A cells. Conversely, the 20alpha-HSO and 3alpha-HSO activities were significantly higher (p < 0.001) in MCF-10A cells than in the other three cell types. In the MCF-10A cells, 20alpha-HSO activity was 8-14-fold higher and the 3alpha-HSO activity was 2.5-5.4-fold higher than in the other three cell types. The values of 5alphaR:20alpha-HSO ratios were 16.9-32.6-fold greater and the 5alphaR:3alpha-HSO ratios were 5.2-10.5-fold greater in MCF-7, MDA-MB-231 and T-47D cells than in MCF-10A cells. RT-PCR showed significantly higher expression of 5alphaR1 (p < 0.001), and lower expression of 20alpha-HSO (p < 0.001), 3alpha-HSO2 (p < 0.001), 3alpha-HSO3 (p < 0.001) in MCF-7, MDA-MB-231 and T-47D cells than in MCF-10A cells.

CONCLUSION

The findings provide the first evidence that the 5alphaR activity (leading to the conversion of progesterone to the cancer promoting 5alpha-pregnanes) is significantly higher in the tumorigenic MCF-7, MDA-MB-231 and T-47D breast cell lines than in the nontumorigenic MCF-10A cell line. The higher 5alphaR activity coincides with significantly greater expression of 5alphaR1. On the other hand, the activities of 20alpha-HSO and 3alpha-HSO are higher in the MCF-10A cells than in MCF-7, MDA-MB-231 and T-47D cells; these differences in activity correlate with significantly higher expression of 20alpha-HSO, 3alpha-HSO2 and 3alpha-HSO3 in MCF-10A cells. Changes in progesterone metabolizing enzyme expression (resulting in enzyme activity changes) may be responsible for stimulating breast cancer by increased production of tumor-promoting 5alpha-pregnanes and decreased production of anti-cancer 20alpha--and 3alpha-4-pregnenes.

In situ detection of O6-methylguanine-DNA methyltransferase messenger RNA in paraffin-embedded human astrocytic tumor tissues by nested in situ RT-PCR is useful in predicting chemotherapy-resistance of tumors

O6-methylguanine-DNA methyltransferase (MGMT) is an enzyme that interferes with chemotherapeutic effect of alkylating agents. We performed in situ detection of MGMT mRNA utilizing the nested RT-PCR method in tissue sections (nested in situ RT-PCR). We analyzed 34 samples of paraffin-embedded astrocytic tumor tissue sections with this method [3 astrocytomas, 14 anaplastic astrocytomas (AA), and 17 glioblastoma multiformes (GBM)]. Twenty-five cases (73.5% of all cases) were positive for MGMT either with our method or immunohistochemistry (IHC). Moreover, with our method >25% of the cells in the tumor tissue expressed MGMT in contrast to >4% with IHC among the population of MGMT positive cases. Our method was significantly more sensitive than IHC (p=0.0004). The present results suggest that potentially there is a greater population of MGMT positive cells in astrocytic tumor tissues than the one evaluated with IHC. These findings suggest that the >25% of the MGMT positive cells are involved in the interference with the chemotherapeutic effect of alkylating agents. The MGMT expressing cell population was markedly decreased in GBM compared with AA (26.1% vs 62.1%). The main reason for this marked decrease was that MGMT was expressed in only 9 of 17 cases of GBM in contrast to all AA cases that expressed MGMT. This result suggests that there are potentially two populations of GBM on the basis of MGMT expression, in which the negative population might be mainly composed of de novo GBM. Therefore, it is suggested that our method is practically useful to detect any drug resistance gene product with high sensitivity and would provide a chance to evaluate the chemotherapeutic effect of any agents in an individual patient based manner.

Inducible nitric oxide synthase-mediated proliferation of a T lymphoma cell line

Nitric oxide (NO)-derived from T lymphocytes in an autocrine fashion can modulate events in the cell. However, the exact role of NO on the control of lymphocyte growth is controversial since both stimulation and inhibition have been demonstrated. Nitric oxide synthase (NOS) activity in normal and tumor T lymphocyte proliferation was studied here. Resting normal T lymphocytes displayed low levels of NOS activity that were slightly increased upon mitogenic stimulation. In contrast, BW5147 T lymphoma cells displayed higher basal levels than normal T lymphocytes that were significantly augmented when induced to proliferate. This activity was slightly modified in the presence of the calcium chelator EGTA and was blocked by competitive and irreversible NOS inhibitors, as well as by selective blockers of iNOS. Furthermore, tumor but not normal cell proliferation was impaired by NOS and iNOS blockers, while a calcium blocker only affected normal cell growth. iNOS expression, both at the protein and at the mRNA levels, was demonstrated on growing BW5147 cells but not on arrested tumor or normal lymphocytes. The contribution of iNOS to sustained proliferation of tumor cells is discussed.

Participation of fibroblasts in MMP-2 binding and activation on the surface of oral squamous cell carcinoma cells

The effect of fibroblasts on the activation of matrix metalloproteinase-2 (MMP-2) in oral squamous cell carcinoma (SCC) cells was examined. The plasma membrane of SCC cells failed to bind and activate latent MMP-2. However, treatment of SCC cells with fibroblast-conditioned medium (fibroblast-CM) led to the enhancement of the binding and activation of latent MMP-2 on the cell surface. Moreover, fibroblasts induced the expression of membrane type 1 MMP (MT1-MMP) in SCC cells. MMP-2 activated on the cell surface bound to the surface of SCC cells via alphav integrins. These findings suggest that fibroblasts might facilitate the invasion of SCC cells by increasing the proteolytic activity on the surfaces of SCC cells.