Dose-dependent Increase In Apoptosis Research Articles

Targeting AKT with the proapoptotic peptide, TAT‐CTMP: A novel strategy for the treatment of human pancreatic adenocarcinoma

Pancreatic adenocarcinoma carries an ominous prognosis and has little effective treatment. Several studies have demonstrated that the potently antiapoptotic phosphatidyl inositol 3'-kinase (PI3K)-protein kinase B/AKT pathway is active in pancreas cancer. A recent study identified an endogenous AKT antagonist, carboxyl terminal modulator protein (CTMP). CTMP inhibits the phosphorylation of AKT, preventing full activation of the kinase. We screened several cell permeable peptides from the N-terminal domain of CTMP (termed TAT-CTMP1-4) in vitro and found one that caused significant apoptosis in pancreatic adenocarcinoma cell lines. An inactive variant of this peptide was synthesized and used as a negative control. In all cell lines tested, TAT-CTMP4 induced a dose-dependent increase in apoptosis as detected by %-TUNEL positive cells and %-active caspase-3 (% active caspase-3 ranged from 31.2 to 61.9 at the highest dose tested (10 microM). A screening of various cell and tissue types revealed that the proapoptotic activity was highest in pancreatic adenocarcinoma. TAT-CTMP induced similar levels of active caspase-3 as several other known inducers of apoptosis: gemcitabine, radiation therapy, wortmannin and recombinant tumor necrosis factor (TNF)-alpha. No apoptosis was observed in donor human peripheral blood mononuclear cells (PBMC, p < 0.01). We further showed that TAT-CTMP4 could augment either gemcitabine chemotherapy or radiation therapy, standard therapies for pancreas cancer. Pancreatic adenocarcinoma xenografts treated with a single dose of TAT-CTMP4 demonstrated a marked increase in caspase-3 positive tumor cells when compared with untreated controls. Additionally, pancreatic adenocarcinoma allografts treated with intratumoral TAT-CTMP and systemic gemcitabine displayed a significantly smaller tumor burden while undergoing treatment than mice in control groups (p < 0.001). These data indicate that inhibiting AKT with CTMP may be of therapeutic benefit in the treatment of pancreatic adenocarcinoma and, when combined with established therapies, may result in an increase in tumor cell death.

C-terminal fragment of transforming growth factor beta-induced protein (TGFBIp) is required for apoptosis in human osteosarcoma cells

Transforming growth factor beta-induced protein (TGFBIp), is secreted into the extracellular space. When fragmentation of C-terminal portions is blocked, apoptosis is low, even when the protein is overexpressed. If fragmentation occurs, apoptosis is observed. Whether full-length TGFBIp or integrin-binding fragments released from its C-terminus is necessary for apoptosis remains equivocal. More importantly, the exact portion of the C-terminus that conveys the pro-apoptotic property of TGFBIp is uncertain. It is reportedly within the final 166 amino acids. We sought to determine if this property is dependent upon the final 69 amino acids containing the integrin-binding, EPDIM and RGD, sequences. With MG-63 osteosarcoma cells, transforming growth factor (TGF)-β1 treatment increased expression of TGFBIp over 72 h ( p < 0.001). At this time point, apoptosis was significantly increased ( p < 0.001) and was prevented by an anti-TGFBIp, polyclonal antibody ( p < 0.05). Overexpression of TGFBIp by transient transfection produced a 2-fold increase in apoptosis ( p < 0.01). Exogenous purified TGFBIp at concentrations of 37–150 nM produced a dose dependent increase in apoptosis ( p < 0.001). Mass spectrometry analysis of TGFBIp isolated from conditioned medium of cells treated with TGF-β1 revealed truncated forms of TGFBIp that lacked integrin-binding sequences in the C-terminus. Recombinant TGFBIp truncated, similarly, at amino acid 614 failed to induce apoptosis. A recombinant fragment encoding the final 69 amino acids of the TGFBIp C-terminus produced significant apoptosis. This apoptosis level was comparable to that induced by TGF-β1 upregulation of endogenous TGFBIp. Mutation of the integrin-binding sequence EPDIM, but not RGD, blocked apoptosis ( p < 0.001). These pro-apoptotic actions are dependent on the C-terminus most likely to interact with integrins.

Mechanisms of Growth Inhibition in Human Papillomavirus Positive and Negative Cervical Cancer Cells by the Chloromethyl Ketone Protease Inhibitor, Succinyl-Alanine-Alanine-Proline-Phenylalanine Chloromethyl Ketone

The chymotrypsin-like serine protease inhibitor, succinyl-alanine-alanine-proline-phenylalanine chloromethyl ketone (AAPF(CMK)), has been shown to have anticarcinogenic activity in a number of model systems and to be relatively selective for a nuclear protease. This inhibitor also has substantial effects on growth of tumorigenic human papillomavirus (HPV)-infected keratinocytes in organotypic raft cultures. Here, we examined the effects of AAPF(CMK) on cell growth, cell-cycle kinetics, apoptosis induction, and DNA synthesis in two human cervical carcinoma cell lines: SiHa cells, which have integrated high-risk HPV-16; and C33a cells, which do not contain HPV DNA. AAPF(CMK) inhibited growth of both cell lines in a time- and dose-dependent manner. Apoptosis studies showed no significant difference in drug-treated versus vehicle-treated cells in the C33a cell line. However, a significant dose-dependent increase in apoptosis occurred at a late time point in SiHa cells. Cell-cycle progression and DNA synthesis assays showed that the cellular mechanisms of growth inhibition by AAPF(CMK) differ between the HPV16-positive and HPV-negative tumorigenic cell lines. Drug-treated C33a cells showed a significant accumulation of cells in the G(2) phase of the cell cycle. In SiHa cells, growth inhibition produced by AAPF(CMK) seemed to result from a global arrest of the cell cycle. Although the molecular mechanisms involved in AAPF(CMK)-induced growth inhibition are distinct between the two tumorigenic cell lines, such differences may ultimately prove to have therapeutic utility. Novel therapies for treating established HPV infections are needed, because HPV is a causative agent in the development of multiple types of cancer.

NF-κB inhibition in human hepatocellular carcinoma and its potential as adjunct to sorafenib based therapy

Nuclear factor-kappaB (NF-κB) has been shown to play an important role in the development and progression of cancer. In this study, we systematically examined NF-κBp65 signaling pathway in both human hepatocellular carcinoma (HCC) tissue and HCC cell lines. NF-κBp65 signaling pathway is aberrantly expressed and activated in both human HCC tissue and HCC Hep3B cells. Inhibition of NF-κB activity significantly reduced proliferation and invasion of Hep3B cells as well as down-regulated the expression of invasion-related molecules including matrix metalloproteinase (MMP)-2, MMP-9, membrane type-1 MMP (MT1-MMP), urokinase plasminogen activator (uPA) and vascular endothelial growth factor (VEGF). Hep3B cells exhibited a dose-dependent increase in apoptosis after receiving sorafenib treatment. Inhibition of NF-κB activity strongly sensitized Hep3B cells to sorafenib-induced cell death. Mechanistically, combined treatment of sorafenib and NF-κB inhibition enhanced inhibition of MAPK signaling and down-regulation of anti-apoptotic protein Mcl-1 expression. These observations indicate that inhibition of NF-κB may be a potential antineoplastic therapy for HCC, especially the combination of NF-κB inhibition and sorafenib provides a novel therapeutic strategy for patients with advanced-stage HCC.

Multicentric investigation of ionising radiation-induced cell death as a predictive parameter of individual radiosensitivity

In the present study, the predictive value of ionising radiation (IR)-induced cell death was tested in peripheral blood lymphocytes (PBLs) and their corresponding Epstein-Barr virus-transformed lymphoblastoid cell lines (LCLs) in an interlaboratory comparison. PBLs and their corresponding LCLs were derived from 15 tumour patients, that were considered clinically radiosensitive based on acute side-effects, and matched controls. Upon coding of the samples, radiosensitivity of the matched pairs was analysed in parallel in three different laboratories by assessing radiation-induced apoptotic and necrotic cell death using annexin V. All participating laboratories detected a dose-dependent increase of apoptosis and necrosis in the individual samples, to a very similar extent. However, comparing the mean values of apoptotic and necrotic levels derived from PBLs of the radiosensitive cohort with the mean values of the control cohort did not reveal a significant difference. Furthermore, within 15 matched pairs, no sample was unambiguously and independently identified by all three participating laboratories to demonstrate in vitro hypersensitivity that matched the clinical hypersensitivity. As has been reported previously, apoptotic and necrotic cell death is barely detectable in immortalised LCL derivatives using low doses of IR. Concomitantly, the differences in apoptosis or necrosis levels found in primary cells of different individuals were not observed in the corresponding LCL derivatives. All participating laboratories concordantly reasoned that, with the methods applied here, IR-induced cell death in PBLs is unsuitable to unequivocally predict the individual clinical radiosensitivity of cancer patients. Furthermore, LCLs do not reflect the physiological properties of the corresponding primary blood lymphocytes with regard to IR-induced cell death. Their value to predict clinical radiosensitivity is thus highly questionable.

Inhibition of Autophagy with 3-Methyladenine Synergistically Enhances Cellular Apoptosis Induced by the Histone Deacetylase Inhibitor PCI 24781 in Non-Hodgkin's Lymphoma Cells

Background: Autophagy represents a potential mechanism of cellular survival in settings of external stressors, such as starvation and exposure to cytotoxic drugs. Driven by the formation of autophagosomes, which digest nonessential cellular components during stress, autogphagy may be pharmacologically inhibited by 3-methyladenine (3-MA), an inhibitor of autophagosome formation. Histone deacetylase inhibitors (HDACI) block cancer cell proliferation by mechanisms that involve epigenetic gene regulation leading to cell growth arrest, differentiation, and apoptosis. Previous investigators have demonstrated synergistic cellular killing by a combination of HDACI and autophagy inhibitors in leukemia cell lines (Carew et al., Blood. 2007).Methods: We investigated whether a similar effect was possible in lymphoma. Specifically, we studied the combination of the pan-HDACI PCI-24781 and 3-MA in three lymphoma cell lines—Ramos (Burkitt's lymphoma), Jeko, and Granta (both mantle cell lymphoma lines). Cells were cultured in RPMI (Invitrogen) and were incubated for 48 hours with 3-MA (1 mM and 2 mM), PCI-24781 (0.125 uM, 0.25 uM, 0.5 uM) and combinations of both agents. Apoptosis was determined by fluorescence-activated cell sorting (FACS) using AnnexinV-FITC/propidium iodide (AnnexinV+/PI+) staining. Western blots were performed to assess markers of apoptosis—beclin-1 and LC3B isoform I to II conversion.Results: In all three cell lines, treatment with PCI-24781 resulted in a dose-dependent increase in apoptosis. Our previous studies have shown that the IC70 (dose to achieve 70% AnnexinV+/PI+) was 1uM for PCI-24781 in the Ramos cell line. When 3-MA was combined with 0.25 uM PCI-24781, apoptosis increased from 13% to 35%. Similarly, 3-MA increased apoptosis from 8% to 18% and from 30% to 50% when added to PCI 24781 0.125 uM and 0.5 uM, respectively. Similar, albeit less striking, trends were seen in Jeko and Granta cells. Synergy was determined in Ramos cells by the combination index (CI) using isobolograms (CalcuSyn software). Moderate synergy was seen at PCI concentrations of 0.25 and 0.5 uM and a 3-MA concentration of 2 mM, with a CI of approximately 0.7. Immunoblots were analyzed for markers of autophagy—beclin-1 and LC3B isoforms I and II. Combined 3-MA and PCI-24781 reduced Beclin-1 expression as well as the conversion of LC3B isoform I to II in cells treated with the PCI-24781and 3-MA combination, as compared to cells treated with PCI-24781 alone, suggesting that inhibition of autophagy is responsible for the synergistic increase in apoptosis. This reduction was most prominent at 6 hours, indicating that autophagy inhibition is a relatively early event in this model.We conclude that inhibition of autophagy with 3-MA represents a novel approach to synergistically enhance cellular apoptosis induced by HDACI in lymphoma cells. Clinical studies taking advantage of this novel biology are warranted.

Enzastaurin renders MCF-7 breast cancer cells sensitive to radiation through reversal of radiation-induced activation of protein kinase C

Enzastaurin (LY317615.HCI), a protein kinase C (PKC)-β inhibitor, has a radiosensitising effect on 4T1 murine breast cancer and human glioma cells; however, the exact mechanism of this action has not been evaluated. The present study investigated the effects of enzastaurin and gamma irradiation on PKC activity in MCF-7 human breast cancer cells in vitro and in vivo. Enzastaurin (5μM) in combination with irradiation (2–8Gy) produced a synergistic decline in MCF-7 clonogenic cell survival. Analysis of MCF-7 cells stained with Annexin V and 7-aminoactinomycin D showed a dose-dependent increase in apoptosis in response to enzastaurin (3, 5 and 7μM) and irradiation (10Gy) compared to irradiation alone. This pro-apoptotic effect was confirmed by increases in caspase-3 and -9 activity. In a MCF-7 xenograft model, irradiation with 25Gy increased PKC-α activity by 2.5-fold compared to untreated controls, whereas PKC-ε and -βII activity was increased by 1.8-fold. Radiation-induced activation of all three anti-apoptotic isoforms of PKC was reversed by pre-treatment with enzastaurin (75mg/kg, twice daily for 3 days). We conclude that enzastaurin has a radiosensitising effect on MCF-7 human xenograft tumours through the reversal of anti-apoptotic activation of PKC isoforms.

Guggulsterone Inhibits Adipocyte Differentiation and Induces Apoptosis in 3T3‐L1 Cells

To determine the effects of guggulsterone (GS), the active substance in guggulipid, on apoptosis, adipogenesis, and lipolysis using 3T3-L1 cells. For apoptosis and lipolysis experiments, mature adipocytes were treated with GS isomers. Viability, apoptosis, and caspase 3/7 activation were quantified using MTS, enzyme-linked immunosorbent assay (ELISA), caspase-Glo 3/7 activity assay, respectively. The expression of cytochrome c was demonstrated by western blot. Lipolysis was quantified by measuring the release of glycerol. For adipogenesis experiments, postconfluent preadipocytes were incubated with GS isomers for up to 6 days during maturation. Adipogenesis was quantified by measuring lipid content using Nile Red dye. Western blot was also used to demonstrate the adipocyte-specific transcription factors peroxisome proliferator-activated receptor gamma2 (PPARgamma2), CCAAT/enhancer binding protein alpha (C/EBPalpha), and C/EBPbeta. In mature adipocytes cis-GS decreased viability, whereas the trans-GS isomer had little effect. Both isomers caused dose-dependent increases in apoptosis and cis-GS was more effective than trans-GS in inducing apoptosis. cis- and trans-GS also increased caspase-3 activity and release of cytochrome c from mitochondria. In maturing preadipocytes, both isomers were equally effective in reducing lipid content. The adipocyte-specific transcription factors PPARgamma2, C/EBPalpha, and C/EBPbeta were downregulated after treatment with cis-GS during the maturation period. Furthermore, cis-GS increased basal lipolysis of mature adipocytes, but trans-GS had no effect. These results indicate that GS isomers may exert antiobesity effects by inhibiting differentiation of preadipocytes, and by inducing apoptosis and promoting lipolysis of mature adipocytes. The cis-GS isomer was more potent than the trans-GS isomer in inducing apoptosis and lipolysis in mature adipocytes.

First Clinical Report of Tipifarnib for the Treatment of T-Large Granular Lymphocyte (LGL) Leukemia.

INTRODUCTION: Lymphoproliferative diseases of large granular lymphocytes (LGL leukemia) are clinical syndromes associated with increased circulating CD3+CD8+CD57+ T-LGL s. Chronic neutropenia, anemia, and arthritis are clinical manifestations mediated by autoimmune reactivity of this lymphocyte population. Previously, we found evidence that extracellular-regulated kinase (ERK) and Ras were constitutively active in the patient's LGLs. Ablation of Ras activity by a dominant-negative form of Ras and pharmacologic inhibition with farnesyltransferase inhibitors FTI2153 and R115777 (tipifarnib, Zarnestra®, Johnson & Johnson) resulted in ERK inhibition and enhanced apoptosis of the leukemic LGLs. A multicenter phase 2 clinical trial using tipifarnib was initiated with a two-stage design. Here we provide the first report of the efficacy and safety of tipifarnib in patients with LGL leukemia.METHODS: Patients were to be treated in the first stage with four cycles of therapy at a dose of 300 mg twice daily for 21 days out of a 28- day intermittent cycle. Key patient entry criteria were neutrophil counts < 500 cells/μl, transfusion-dependent anemia, and clonal CD3+/CD57+ T-cells greater than 350 cells/μl in the peripheral blood. WBC, ALC, hemoglobin, platelet counts, and ANC were determined. Bone marrow biopsies were performed on all patients prior to therapy and then repeated when worsening cytopenias occurred. Tipifarnib was stopped when bone marrow cellularity was reduced by 50% compared to baseline. Bone marrow colony formation assessed using14-day CFU-GM and BFU-E assays in methycellulose (Stem Cell Separation Systems, Vancouver BC). Growth factor support with G-CSF was allowed during the 7 days off when ANCs were < 500 cells/μl.RESULTS: Five males and two females (mean 57 years old) received tipifarnib. Four patients failed to complete the study due to toxicity. Three patients were removed from study due to grade 3–4 bone marrow toxicity and/or infections requiring hospitalization and a tipifarnib-unrelated death occurred in one patient. Three patients completed four cycles and were evaluated for response with a dose reduction for bone marrow toxicity required in one of these evaluable patients. Leukemic LGL cells from the three evaluable patients displayed a dose-dependent increase in apoptosis in vitro and treatment was associated with reduced ALCs in two cases. None of the patients met the pre-determined criteria for response. However, one patient, shown to be growth factor unresponsive prior to therapy, had an increase in ANC from 0 at baseline to 8,600 cells/μl while receiving G-CSF on week 16. The number of bone marrow colonies also increased in this patient after therapy. All bone marrow biopsies, which were required in five cases, showed significantly improved erythroid or myeloid differentiation.CONCLUSIONS: Improvements in bone marrow differentiation suggest that tipifarnib may prove beneficial for the treatment of LGL leukemia if a safe dose and schedule is established and the treatment prolonged to allow for bone marrow recovery.

Characterization of the Effects of Cyclooxygenase-2 Inhibition in the Regulation of Apoptosis in Human Small and Non–Small Cell Lung Cancer Cell Lines

Cyclooxygenase-2 enzyme (COX-2) is overexpressed in human non-small cell lung cancer (NSCLC) but is not expressed in small cell lung cancer. Selective COX-2 inhibitors have been shown to induce apoptosis in NSCLC cells, an effect which is associated with the regulation of intracellular MAP kinase (MAPK) signal pathways. Our aims were to characterize the effects of COX-2 inhibition by rofecoxib on apoptosis in human NSCLC and small cell lung cancer cell lines. The human NSCLC cell line NCI-H2126 and small cell lung cancer cell line DMS-79 were used. Constitutive COX-2 protein levels were first determined by Western blot test. Levels of apoptosis were evaluated by using propidium iodide staining on FACScan analysis after incubation of NCI-H2126 and DMS-79 with p38 MAPK inhibitor SB202190 (25 ?microM), NF-kappaB inhibitor SN50 (75 microg/mL), and rofecoxib at 100 and 250 microM. All statistical analysis was performed by analysis of variance. Western blot test confirmed the presence of COX-2 enzyme in NCI-H2126 and absence in DMS-79. Interestingly, rofecoxib treatment demonstrated a dose-dependent increase in apoptosis in both cell lines. Given this finding, the effect of rofecoxib on NF-kappaB and p38 MAPK pathways was also examined. Apoptosis in both cell lines was unaltered by SN50, either alone or in combination with rofecoxib. A similar phenomenon was observed in NCI-H2126 cells treated with SB202190, either alone or in combination with rofecoxib. In contrast, p38 MAPK inhibition greatly upregulated DMS-79 apoptosis in a manner that was unaltered by the addition of rofecoxib. Rofecoxib led to a dose-dependent increase in apoptosis in both tumor cell lines. This effect occurred independently of COX-2, NF-kappaB, and p38 MAPK pathways in DMS-79 cells. As such, rofecoxib must act on alternative pathways to regulate apoptosis in human small cell lung cancer cells.

3‐Phosphoinositide‐dependent protein kinase‐1/Akt signalling and inhibition in a canine prostate carcinoma cell line

Deregulation of the 3-phosphoinositide-dependent protein kinase-1 (PDK-1)/Akt signalling pathway is associated with prostate cancer development and progression. Inhibition of PDK-1/Akt signalling can be achieved using structurally optimized celecoxib derivatives such as OSU-03012. In this study, we treated the novel canine prostate cancer cell line, Ace-1, with OSU-03012 or dimethyl sulphoxide in vitro. We found that Akt was constitutively phosphorylated in the canine prostate cancer cell line Ace-1 and that there was a dose-dependent decrease in cell viability, and Akt and glycogen synthase kinase-3beta phosphorylation, in response to OSU-03012 treatment. This was accompanied by a dose-dependent increase in apoptosis. These data suggest that Akt signalling pathway inhibition is a potential strategy for the treatment of dogs with prostate cancer and that canine prostate cancer is a relevant large animal model for evaluating Akt pathway inhibitors such as OSU-03012 for use in people.

Apomine™, an inhibitor of HMG-CoA-reductase, promotes apoptosis of myeloma cells in vitro and is associated with a modulation of myeloma in vivo

Apomine, a novel 1,1 bisphosphonate ester, increases the rate of degradation of HMG-CoA reductase, inhibiting the mevalonate pathway and thereby blocking cholesterol biosynthesis. We have investigated whether Apomine can induce myeloma cell apoptosis in vitro and modulate myeloma disease in vivo. Apomine induced a dose-dependent increase in apoptosis in NCI H929, RPMI 8226 and JJN-3 human myeloma cells. Apomine, unlike the bisphosphonate, alendronate, had no measurable effect on osteoclastic bone resorption in vitro. To investigate the effect of Apomine in vivo, 5T2MM murine myeloma cells were injected into C57BL/KaLwRij mice. After 8 weeks all animals had a serum paraprotein and were treated with Apomine (200 mg/kg), or vehicle, for 4 weeks. Animals injected with 5T2MM cells and treated with vehicle developed osteolytic bone lesions, reduced cancellous bone area, decreased bone mineral density (BMD) and increased osteoclast number. Apomine caused a decrease in serum paraprotein and a decrease in tumor burden. Apomine inhibited the development of osteolytic lesions and prevented the tumor-induced decreases in BMD. Apomine had no effect on osteoclast number in contrast to what had been seen previously with the bisphosphonate, zoledronic acid, suggesting that these are direct effects of Apomine on myeloma cells. This demonstrates that Apomine is able to promote myeloma cell apoptosis in vitro and inhibit the development of multiple myeloma and lytic bone disease in vivo. The use of bisphosphonate esters such as Apomine represents a novel therapeutic approach in the treatment of myeloma and, indirectly, the associated bone disease.

Apoptosis, proliferation and differentiation patterns are influenced by Zebularine and SAHA in pancreatic cancer models

Objective. Pancreatic cancer continues to be an urgent clinical problem. We used the novel DNA methyltransferase inhibitor Zebularine and the histone deacetylase inhibitor SAHA to investigate the epigenetic influence on viability and differentiation of the pancreatic cancer cell lines YAP C, DAN G and Panc-89 in vitro and in vivo. Material and methods. Cell vitality, proliferation and expression of PDX-1, cytokeratin 7 and 20, chromogranin A, vimentin, bax and bcl-2 were determined on the protein and mRNA level in vitro and in a subcutaneous xenograft model. Results. A time- and dose-dependent increase of apoptosis, paralleled by decreased proliferation, was observed after incubation with single agents or a combination therapy with lower concentrations. This was associated with up-regulation of pro-apoptotic bax and a phenotypic stabilization by the enhanced expression of cytokeratin 7. In vivo, growth of xenografts was delayed with the most pronounced effect in Panc-89 after 1 week of daily intraperitoneal injections of Zebularine paralleled with CK7 up-regulation and down-regulation of dedifferentiation markers. Conclusions. Epigenetic modulation via inhibition of DNA methyltransferase and histone deacetylase induces apoptosis in human pancreatic cancer cells in vitro and delays xenograft growth in vivo, which is associated with a morphological/molecular phenotypic stabilization. These compounds may therefore be suitable as adjunctive therapeutic agents in the treatment of pancreatic cancer.

Translational In Vivo and In Vitro Studies in Patients (pts) with Acute Myeloid Leukemia (AML), Chronic Myeloid Leukemia (CML) and Myeloproliferative Disease (MPD) Treated with MK-0457 (MK), a Novel Aurora Kinase, Flt3, JAK2, and Bcr-Abl Inhibitor.

Introduction: MK-0457 (VX-680) is a small molecule kinase inhibitor of the Aurora kinases A/B, wild type and mutant (T315I) Bcr-Abl, Flt3, and Jak2 (V617F) with preclinical activity in solid and hematological tumor models. We report correlative laboratory studies from pts with AML, CML and MPD enrolled in a Phase I/II study with MK-0457, on a 5-day continuous intravenous infusion (CIV), dose escalation schedule given at 2 to 3 week intervals.Methods: Specimens from 6 MPD (all Jak2 (V617F) positive), 6 CML pts in accelerated/blastic phase (3/6 positive for T315I) and 3 AML pts with at least two study time points were assessed for apoptosis (AnnexinV (AV)/PI by FACS) and cell cycle (PI) changes in vivo. A CD34+ progenitor sub-population was studied. PBMC isolated prior to therapy were cultured in vitro with MK-0457, either alone or in co-culture with human, BM-derived mesenchymal stem cells (MSC). Concentration and time dependent apoptosis and cell cycle changes were determined.Results: At day 5, there was no significant induction of apoptosis in 5/6 MPD pts compared to baseline (BL) (mean for total cell population 37 vs 27%; gated myeloid subpopulation 37 vs 38%). All pts had a hematological response and, except one, a slight decrease in Jak2 (V617F) transcript levels. In vivo, CML pts showed a heterogeneous response. 3/5 pts had an increase (7, 98, 103 %) in AV/PI positive cells and 2/5 pts a decrease (−28, −74%) at day 5, one of which in lymphoid BC, exhibited delayed massive apoptosis at day 11 (470% increase from BL). The other pt without evidence of apoptosis induction achieved a hematological response with disappearance of the T315I clone, relapsing with high Bcr-Abl transcript levels thereafter. A pt with partial cytogenetic and molecular response had high BL apoptosis (50%) that remained high (58%) at 90 days when taken off study due to side effects (muscle cramps/pain). In vitro, a dose dependent rise in specific apoptosis was seen in MPD cells between 48–144 hrs, reaching statistical significance at 50–400 nM MK (p=0.017−0.008, two tailed t-test, unequal variance) and in CML cells at 24, 48, 72 hrs (mean increase at 400nM MK of 17, 14, 28%, respectively in CML, p≤0.05 for mean of all time points). In AML, 2/3 pts had increased numbers of AV/PI positive cells on day 5, declining to BL levels on day 11 in one pt. In vitro, AML specimens (from non-study pts) showed less pronounced apoptosis than MPD and CML cells, with similar effects in CD34 cells. Co-incubation with MSC protected cells of AML and MPD pts at all drug concentrations, reaching significance at ≥100nM in MPD pts (p=0.03). In cell line experiments, HL-60 and OCI-AML cells showed striking G2/M block, polyploidization and apoptosis.Conclusion: In preliminary experiments, MK-0457 induces apoptosis in AML and CML pts in vivo, shows a time and dose dependent increase of apoptosis in vitro in MPD, CML and AML pts cells and leads to accumulation in G2/M phase. Co-culture with human MSC protect cells from MPD and AML pts in vitro. The clinical trial is ongoing and molecular profiling studies are underway.

Complex Immunosuppressive Action of Farnesyltransferase Inhibitor (FTI) R115777 (Tipifarnib, Zarnestra®) with Induction of Apoptosis in T Cells from Patients with Large Granular Lymphocyte (LGL) Leukemia.

BACKGROUND: Large Granular Lymphocyte (LGL) leukemia is an indolent clonal disorder arising from either CD3+ or CD3− immunophenotypes characterized as T-cell and Natural-Killer (NK)-cell malignancies, respectively. Due to a rare incidence, all therapeutic investigations in LGL leukemia are generated from single institution experiences, which consist primarily of retrospective cohort analyses. Pathogenesis may relate to an underlying autoimmune mechanism with low-dose methotrexate (10mg/m2 weekly), cyclophosphamide (50–100mg daily), and cyclosporine A (5–10mg/kg daily) used as first-line agents for the treatment of associated cytopenias. The mechanism(s) controlling survival of leukemic LGL are not fully characterized. We hypothesize that agents that target survival signaling will serve as effective therapeutics. Using pharmacologic inhibitors of the Mitogen Activated Protein Kinase (MAPK/ERK) signaling cascase, we found that ERK/Ras drives NK leukemia survival (Epling-Burnette, et al. Oncogene, 23:9220, 2004). The goal of this study was to investigate the in vitro actions of the farnysltransferase-inhibitor R115777 (tipifarnib, Zarnestra®, Johnson and Johnson) on survival and immune response leukemic T cells.METHODS: Peripheral blood mononuclear cells (PBMCs) were isolated from patients with T LGL leukemia. All patients had increased numbers of CD3+ αβ T lymphocytes and evidence of clonality. Western blot analysis was used to examine the protein levels of phosphorylated (active) ERK1 and ERK2 (MAPK), Bcl-2, and total MAPK. Apoptosis assays were performed by staining with annexin-V-FITC and 7-aminoactinomycin (7-AAD) and flow cytometry analysis. Anti-CD3 plus anti-CD28 was used to stimulate T cells in the presence of brefelden A and IL-2, IFN-γ, TNF-α, IL-4, and IL-10 were determined in distinct T cell subpopulations by intracellular staining. T cell proliferation was assessed by Brdu incorporation in CD4+ and CD8+ T cells.RESULTS: PBMCs from patients with T LGL displayed constitutively-active MAPK/ERK expression as determined by Western blot analysis (n=5). Using MEK pharmacological inhibitors, we found that blockade of the active MEK/ERK signaling pathway induced apoptosis in leukemic T LGL. Bcl-2 was expressed in 80% of patients and when MEK/ERK was inhibited there was a corresponding reduction in expression. Targeted disruption of farnesyl-transferase with two different inhibitors (FTI2153 and R115777, n=9) led to a dose-dependent increase in apoptosis with an apoptotic index that was significantly greater than normal T cells. In addition to apoptosis, we found that antigen-induced proliferation of CD4+ and CD8+ T cells was impaired by R115777 (11% ± 7 vs. 3% ±1.7 and 11% ± 9 vs. 3% ± 1.6, respectively). Furthermore, R115777 biased antigen-dependent cytokine response to a Th2 type with increased expressionof IL-4 and IL-10 after drug treatment (average increase 100% and 43%, respectively).CONCLUSIONS: These findings suggest that FTIs regulate immune response and lead to apoptosis of leukemic T LGL cells. A pilot trial of R115777 (tipifarnib, Zarnestra®) is ongoing for the treatment of LGL leukemia.

Effects of the dual 5 α‐reductase inhibitor dutasteride on apoptosis in primary cultures of prostate cancer epithelial cells and cell lines

The profound reduction in serum dihydrotestosterone (DHT) observed with the dual 5 alpha-reductase inhibitor (5ARI) dutasteride makes it an attractive agent for prostate cancer therapy. The objective of the current study was to determine whether dutasteride would induce apoptosis in a range of prostate epithelial cell lines and primary cultures. Both human prostate androgen-sensitive cell lines (PwR-1E, PNT-2, LNCaP, and PC3[AR2]) and an androgen-independent cell line (PC-3) were grown to confluence. Primary epithelial cells extracted from fresh prostate cancer radical prostatectomy specimens also were grown to confluence under optimal conditions. Total cellular protein was extracted to confirm cytokeratin 18 and antihuman alpha-methylacyl-CoA racemase (AMACR) expression of the primary cells. Apoptosis was assessed by propidium iodide DNA staining and flow cytometry after 24 hours of culture in from 0 microM to 10 microM of dutasteride. Dutasteride induced a dose-dependent increase in apoptosis in the androgen-sensitive prostate cell lines PwR-1E, PNT-2, and LNCaP and in the androgen receptor-expressing PC3(AR2) cell line. However, there was no significant apoptosis noted in the parental PC-3 cells. Of 16 primary epithelial cultures that were treated, 7 cultures were induced to undergo apoptosis, and 9 cultures were unresponsive. All primary cultures were positive for cytokeratin 18 expression, confirming their epithelial phenotype. Responder epithelial cells were positive for AMACR expression. The results of the current study confirmed that dutasteride differentially induced apoptosis in a subset of prostate cell lines and primary prostate epithelial cells. Understanding the cellular phenotype may indicate susceptible cells.

Ochratoxin A: Apoptosis and Aberrant Exit from Mitosis due to Perturbation of Microtubule Dynamics?

Ochratoxin A (OTA) is a potent nephrotoxin and causes high incidences of renal tumors in rodents. The molecular events leading to tumor formation by OTA are not well defined. Early pathological changes observed in kidneys of rats treated with OTA in vivo include frequent mitotic and abnormally enlarged cells, detachment of tubule cells, and apoptosis within the S3 segment of the proximal tubule, suggesting that OTA may interfere with molecules involved in the regulation of cell division and apoptosis. In this study, treatment of immortalized human kidney epithelial (IHKE) cells with OTA (0-50 microM) resulted in a time- and dose-dependent increase in apoptosis and activation of c-Jun N-terminal kinase. At the same time, OTA blocked metaphase/anaphase transition and led to the formation of aberrant mitotic figures and giant cells with abnormally enlarged and/or multiple nuclei, sometimes still connected by chromatin bridges. Immunostaining of the mitotic apparatus using an alpha-tubulin antibody revealed defects in spindle formation. In addition, OTA inhibited microtubule assembly in a concentration-dependent manner in a cell-free, in vitro assay. Interestingly, treatment with OTA also resulted in activation of the transcription factor nuclear factor kappa B (NFkappaB), which has recently been shown to promote cell survival during mitotic cell cycle arrest. Based on these observations, we hypothesize that the mechanism by which OTA promotes tumor formation involves interference with microtubuli dynamics and mitotic spindle formation, resulting in apoptosis or-in the presence of survival signals such as stimulation of the NFkappaB pathway-premature exit from mitosis. Aberrant exit from mitosis resulting in blocked or asymmetric cell division may favor the occurrence of cytogenetic abnormalities and may therefore play a critical role in renal tumor formation by OTA.

RETRACTED: Berberine inhibits growth, induces G1arrest and apoptosis in human epidermoid carcinoma A431 cells by regulating Cdki–Cdk-cyclin cascade, disruption of mitochondrial membrane potential and cleavage of caspase 3 and PARP

Chemotherapeutic approach using non-toxic botanicals may be one of the strategies for the management of the skin cancers. Here we report that in vitro treatment of human epidermoid carcinoma A431 cells with berberine, a naturally occurring isoquinoline alkaloid, decreased cell viability (3-77%, P < 0.05-0.001) and induced cell death (3-51%, P < 0.01-0.001) in a dose (5-75 microM)- and time (12-72 h)-dependent manner, which was associated with an increase in G(1) arrest. G(0)/G(1) phase of the cell cycle is known to be controlled by cyclin dependent kinases (Cdk), cyclin kinase inhibitors (Cdki) and cyclins. Our western blot analysis showed that berberine-induced G(1) cell cycle arrest was mediated through the increased expression of Cdki proteins (Cip1/p21 and Kip1/p27), a simultaneous decrease in Cdk2, Cdk4, Cdk6 and cyclins D1, D2 and E and enhanced binding of Cdki-Cdk. In additional studies, treatment of A431 cells with berberine (15-75 microM) for 72 h resulted in a significant dose-dependent increase in apoptosis (31-60%, P < 0.05-0.001) than non-berberine-treated control (11.7%), which was associated with an increased expression of pro-apoptotic protein Bax, decreased expression of anti-apoptotic proteins Bcl-2 and Bcl-xl, disruption of mitochondrial membrane potential, and activation of caspases 9, 3 and poly (ADP-ribose) polymerase. Pretreatment of A431 cells with the pan-caspase inhibitor (z-VAD-fmk) significantly blocked the berberine-induced apoptosis in A431 cells confirmed that berberine-induced apoptosis is mediated through activation of caspase 3-dependent pathway. Together, this study for the first time identified berberine as a chemotherapeutic agent against human epidermoid carcinoma A431 cells in vitro, further in vivo studies are required to determine whether berberine could be an effective chemotherapeutic agent for the management of non-melanoma skin cancers.

Massive Apoptosis Erodes Nasal Mucosa of Cocaine Abusers

A threatening occurrence in some cocaine abusers is the progressive destruction of nasal structures (cocaine-induced midline destructive lesions [CIMDL]) that may end in a highly severe disease. Thirty patients with CIMDL, 10 healthy patients, 10 patients affected by nasal polyposis, and 10 patients affected by Wegener granulomatosis were observed. Biopsy specimens of nasal mucosa were analyzed by immunohistochemistry for caspases-3, -9 and -8 and by the terminal deoxynucleotidyl transferase-mediated dUTP-digoxygenin nick end labeling (TUNEL) method. The time and concentration-dependent effects of cocaine in vitro were studied in HaCat cells by TUNEL and Western blotting. All CIMDL biopsy specimens showed abundant caspase-3 and caspase-9 expression but no caspase-8 positive cells. No obvious expression of any caspases was detected in biopsy specimens from healthy subjects or in patients affected by nasal polyposis or Wegener granulomatosis. In HaCat cells cellular changes were observed, which confirmed induction of massive apoptotic events. The rate of apoptosis in HaCat cells was dependent on the concentration of cocaine. After 1 hour, 2.5, 5, and 10 mM of cocaine induced 16, 45, and 84% of apoptotic figures, respectively, while 6 hours of exposure increased apoptosis to 25, 54, and 94% at the same concentrations. Caspase expression and activation in HaCat cells treated with 100 microM and 1 mM of cocaine for 1 hour were confirmed by Western blotting. Cultured epithelial cells show both time- and dose-dependent increases in apoptosis and cellular damage on cocaine treatment. We suggest that some abusers trigger CIMDL by abnormally boosting apoptosis within nasal epithelial cells. Cocaine abusers with higher apoptotic rates may predict whether they will eventually develop CIMDL.

Mitochondrial dysfunction in S‐(1,2‐dichlorovinyl)‐L‐cysteine (DCVC)‐induced apoptosis and necrosis in human proximal tubular cells

Confluent, primary cultures of human proximal tubular (hPT) cells were used to determine the relationship between mitochondrial dysfunction and cell death induced by DCVC, a nephrotoxic metabolite of trichloroethylene. Previous studies showed that DCVC causes cellular necrosis only at relatively high doses (> 100 μM) and long incubation times (> 24 hr) whereas both apoptosis and enhanced cellular proliferation occur at relatively low doses (10–100 μM) and early incubation times (2–8 hr). hPT cells were preincubated for 30 min with cyclosporin A (CsA), an inhibitor of the mitochondrial permeability transition. DCVC caused a modest, time- and dose-dependent increase in apoptosis. CsA prevented the increase in apoptosis with 10 or 50 μM DCVC but increased apoptosis with 100 μM DCVC. Necrosis was only observed in cells incubated with 100 μM DCVC for 24 hr, and was diminished by CsA. CsA also prevented decreases in membrane potential and cellular concentrations of ATP. Thus, mitochondrial dysfunction plays a central role in controlling the response of hPT cells to DCVC and inhibition of the mitochondrial permeability transition shifts this response from necrosis to apoptosis at relatively high doses of DCVC or from apoptosis to protection at relatively low doses of DCVC. Supported by NIH Grant ES08828.