Biomedical subjects

Daniel J Lindner

Publications and source records attributed to Daniel J Lindner.

18 recordsLinked to original sources

PubMed2006

Efficacy of SSG and SSG/IFNalpha2 against human prostate cancer xenograft tumors in mice: a role for direct growth inhibition in SSG anti-tumor action.

BACKGROUND: Pre-clinical activity of SSG against melanoma and renal cancer has been identified recently although the drug's mechanism of action and activity against tumors of additional histological-types remain undefined. METHODS: The effects of SSG and SSG combination with other agents on DU145 human prostate carcinoma xenograft tumors in mice and on DU145 cell subpopulations of differential SSG sensitivities were evaluated. RESULTS: DU145 tumor growth was inhibited by SSG (69%), IFNalpha2 (33%) or the combination (80%) that induced complete regression of WM9 human melanoma tumors. DU145 cells in culture were also partially growth inhibited by SSG at killing doses (200-800 mug/ml) for WM9 cells, indicating a correlation of SSG inhibition of cancer cell growth in vitro and in vivo. DU145 cells formed multiple micro tumors in mice treated with SSG or SSG/IFNalpha2 in contrast to the single large tumors in the control or IFNalpha2-treated mice, suggesting the existence of an SSG-resistant subpopulation in DU145 cells. Indeed, DU145 but not WM9 cells formed colonies (approximately 4% frequency) when cultured in the presence of SSG. Single cell clone (DU145-7) isolated from DU145 cells showed SSG-resistant growth in culture, unassociated with cross-resistance to IFNalpha2 and converted to SSG-responsive cells by BSO that inhibited intracellular glutathione levels. CONCLUSIONS: These results implicate a role for direct growth inhibition in SSG anti-tumor action, provide novel insights into the mechanism of tumor resistance to the drug and suggest a therapeutic potential for SSG and its combinations with IFNalpha2 or BSO for prostate cancer that warrants further investigation.

Animals↗

PubMed2006

IFN-alpha1,8 inhibits tumor-induced angiogenesis in murine angiosarcomas.

Interferon-alpha (IFN-alpha) has proved effective in the treatment of hemangiomas, hemangioblastomas, and Kaposi's sarcoma. To investigate the ability of IFNs to inhibit angiosarcoma, we used two transformed murine endothelial cell lines that form angiosarcomas in vivo. SVR and MS1-VEGF cell lines express oncogenic H-ras or vascular endothelial growth factor (VEGF), respectively. IFN-alpha1,8, which is active against murine and human cells, inhibited SVR and MS1-VEGF proliferation in vitro by 40% at 10(3) U/mL (p = 0.028). In vivo, IFN-alpha1,8 inhibited SVR tumor volume by 71% (p = 0.047) and MS1-VEGF volume by 79% (p = 0.003). Tumor-induced angiogenesis was decreased in SVR tumors by 52% (p = 0.005) and in MS1-VEGF tumors by 58% (p = 0.001). Sera from IFN-alpha1,8-treated mice bearing either SVR or MS1-VEGF tumors demonstrated a 5-fold increase in IP-10/CXCL10 (p = 0.001), an IFN-induced antiangiogenic protein. Both recombinant IP-10 and IFN-alpha1,8 inhibited human umbilical vein endothelial cell (HUVEC) vessel formation in the fibrin gel assay, a three-dimensional culture model of angiogenesis, by 56% at 25 ng/mL and 50% at 1.2 ng/mL, respectively (p < 0.001). An IP-10 blocking antibody restored vessel formation to 80% of untreated controls (p = 0.001). Given the magnitude of the in vivo response, these data suggested that the antitumor effects of IFN-alpha1,8 were likely mediated through angiogenesis inhibition rather than solely by direct inhibition of tumor cell proliferation.

Animals↗

PubMed2006

Short communication: phase I clinical and gene modulatory evaluation of tamoxifen and IFN-alpha2b.

Preclinical studies had determined that tamoxifen and interferon-alpha2b (IFN-alpha2b) synergistically inhibited growth of both estrogen-receptor positive and negative murine tumor xenografts and had combined antiangiogenic effects and that tamoxifen potentiated IFN-stimulated gene (ISG) expression. A phase I trial in 26 patients was conducted using the combination to define tolerance and potentiation of ISG expression. IFN- alpha2b at a dose of 3 x 10(6) units/m(2) daily was given subcutaneously (s.c.), and tamoxifen was initiated as a loading dose of 150 mg/m(2) and then 60 mg/m(2) twice daily on day 8. At this initial dose, reduction of dose of IFN- alpha2b was required in 4 of 11 patients, primarily because of fatigue. Another group of patients was treated with an identical tamoxifen dose but with IFN-alpha2b reduced to 2 x 10(6)/m(2) U; this was better tolerated. As the projected serum tamoxifen level to reduplicate preclinical effects was 300 mg/m(2), dose escalation in a third cohort was undertaken; it had to be discontinued secondary to grade III or IV toxicity in 2 of 2 patients. Increases in products of transcriptionally regulated ISGs, beta (2)-microglobulin, neopterin, and ISG15 were assessed. All ISGs increased after IFN-alpha2b, but only ISG15 had a further significant rise after initiation of tamoxifen. Because at doses not limited by unacceptable toxicities, no marked potentiation of ISGs by tamoxifen could be identified, clinical evaluation of the combination was terminated.

Angiogenesis Inhibitors↗

PubMed2006

Human telomerase RNA degradation by 2'-5'-linked oligoadenylate antisense chimeras in a cell-free system, cultured tumor cells, and murine xenograft models.

Ribonuclease L (RNase L) is a latent single-stranded RNA-directed endoribonuclease that is activated on binding to short 2'-5'-linked oligoadenylates (2-5A), a feature that has led to its use in antisense therapeutic strategies. By attaching a 2-5A moiety to the 5' terminus of standard antisense oligonucleotides, it is possible to activate RNase L and guide it to specific RNAs for degradation. These 2-5A antisense chimeras have been used successfully to target a variety of cellular and viral RNAs. Telomerase is a nuclear ribonucleoprotein complex that elongates telomeric DNA and contributes to cellular immortalization. Telomerase is composed of a protein catalytic subunit and an RNA (hTR or TERC) component, both of which are critical for holoenzyme activity. We describe the characterization of 2-5A antisense chimeras targeting the hTR component of telomerase (2-5A antihTR). Newly designed 2-5A anti-hTR molecules were assayed for their abilities to selectively degrade hTR in a cell-free system. Of the five chimeras tested, one (RBI011) degraded hTR by 97%, and two others (RBI013 and RBI009) were also found to be highly active (73-76% degradation). The ability of transfected RBI011, and its homolog RBI254, to degrade hTR in cultured tumor cells was assessed by real-time RT-PCR. In these studies, RBI011 and RBI254 effectively degraded hTR in a variety of hTR-positive tumor cell lines. The hTR degradation studies were extended to growth assays to determine whether hTR ablation affected tumor cell viability or proliferation. RBI254 treatment resulted in reduced tumor cell viability over the course of 4-day growth assays, effects that were augmented by cotreatment with interferon-beta. To extend these results to an in vivo system, nude mice were implanted subcutaneously or orthotopically with hTR-positive prostate tumors and treated with RBI254. RBI254-treated mice exhibited enhanced tumor cell apoptosis and reduced tumor volume as compared with controls. These findings demonstrated the effectiveness of highly active forms of 2-5A antisense against hTR, and also highlight the usefulness of the cell-free system in predicting chimera efficacy before to inception of cell-based and in vivo studies.

Animals↗

PubMed2006

Nitrosylcobalamin promotes cell death via S nitrosylation of Apo2L/TRAIL receptor DR4.

We have previously demonstrated that nitrosylcobalamin (NO-Cbl), an analogue of vitamin B12 that delivers nitric oxide (NO), had potent antiproliferative activity against several human cancer cell lines. NO-Cbl induced apoptosis via a death receptor/caspase-8 pathway. In this study, we demonstrate that a functional Apo2L/TRAIL receptor was necessary for the induction of cell death by NO-Cbl. Furthermore, the Apo2L/TRAIL death receptor DR4 (TRAIL R1) was S nitrosylated following NO-Cbl treatment. Human melanoma (A375), renal carcinoma (ACHN), and ovarian carcinoma (NIH-OVCAR-3) cells were treated with NO-Cbl and subjected to the biotin switch assay; S-nitrosylated DR4 was detected in all three cell lines. NO-Cbl treatment did not cause S nitrosylation of DR5. The seven cysteine residues located in the cytoplasmic domain of DR4 were individually point mutated to alanines. NIH-OVCAR-3 cells expressing the DR4 C336A mutation lacked S nitrosylation following NO-Cbl treatment. Overexpression of wild-type DR4 sensitized cells to growth inhibition by NO-Cbl. Cells expressing the DR4 C336A mutant were more resistant to NO-Cbl and Apo2L/TRAIL than were the other six C-A mutations or wild-type cells. The C336A mutant also displayed blunted caspase-8 enzymatic activity following NO-Cbl treatment compared to the other mutants. Thus, DR4 residue C336 becomes S nitrosylated and promotes apoptosis following NO-Cbl treatment.

Caspase 8↗

PubMed2005

Sodium stibogluconate interacts with IL-2 in anti-Renca tumor action via a T cell-dependent mechanism in connection with induction of tumor-infiltrating macrophages.

IL-2 therapy results in 10-20% response rates in advanced renal cell carcinoma (RCC) via activating immune cells, in which the protein tyrosine phosphatase Src homology 2 domain-containing phosphatase 1 (SHP-1) is a key negative regulator. Based on finding that sodium stibogluconate (SSG) inhibited SHP-1, the anti-RCC potential and action mechanism of SSG and SSG/IL-2 in combination were investigated in a murine renal cancer model (Renca). Despite its failure to inhibit Renca cell proliferation in cultures, SSG induced 61% growth inhibition of Renca tumors in BALB/c mice coincident with an increase (2-fold) in tumor-infiltrating macrophages (Mphi). A combination of SSG and IL-2 was more effective in inhibiting tumor growth (91%) and inducing tumor-infiltrating Mphi (4-fold), whereas IL-2 alone had little effect. Mphi increases were also detected in the spleens of mice treated with SSG (3-fold) or SSG/IL-2 in combination (6-fold), suggesting a systemic Mphi expansion similar to those in SHP-deficient mice. T cell involvement in the anti-Renca tumor action of the combination was suggested by the observations that the treatment induced spleen IFN-gamma T cells in BALB/c mice, but failed to inhibit Renca tumor growth in athymic nude mice and that SSG treatment of T cells in vitro increased production of IFN-gamma capable of activating tumoricidal Mphi. The SSG and SSG/IL-2 combination treatments were tolerated in the mice. These results together demonstrate an anti-Renca tumor activity of SSG that was enhanced in combination with IL-2 and functions via a T cell-dependent mechanism with increased IFN-gamma production and expansion/activation of Mphi. Our findings suggest that SSG might improve anti-RCC efficacy of IL-2 therapy by enhancing antitumor immunity.

Animals↗

PubMed2005

Apo2L/TRAIL induction and nuclear translocation of inositol hexakisphosphate kinase 2 during IFN-beta-induced apoptosis in ovarian carcinoma.

Previously, we have reported that overexpression of IHPK2 (inositol hexakisphosphate kinase 2) sensitized NIH-OVCAR-3 ovarian carcinoma cell lines to the growth-suppressive and apoptotic effects of IFN-beta (interferon-beta) treatment and gamma-irradiation. In the present study, we demonstrate that Apo2L/TRAIL (Apo2L/tumour-necrosis-factor-related apoptosis-inducing ligand) is a critical mediator of IFN-induced apoptosis in these cells. Compared with IFN-alpha2, IFN-beta is a more potent inducer of Apo2L/TRAIL and IHPK2 activity. Overexpression of IHPK2 converts IFN-alpha2-resistant cells into cells that readily undergo apoptosis in response to IFN-alpha2. In untreated cells transfected with IHPK2-eGFP (where eGFP stands for enhanced green fluorescent protein), the fusion protein is localized to the cytoplasm and perinuclear region. After treatment with IFN-beta, IHPK2-eGFP translocated to the nucleus. In cells transfected with mutant IHPK2-NLS-eGFP (where NLS stands for nuclear localization sequence), containing point mutations in the NLS, the fusion protein remained trapped in the cytoplasm, even after IFN-beta treatment. Cells expressing mutant NLS mutation were more resistant to IFN-beta. The IC50 value of IHPK2-expressing cells was 2-3-fold lower than vector control. The IC50 value of NLS-mutant-expressing cells was 3-fold higher than vector control. Blocking antibodies to Apo2L/TRAIL or transfection with a dominant negative Apo2L/TRAIL receptor (DR5Delta) inhibited the antiproliferative effects of IFN-beta. Thus overexpression of IHPK2 enhanced apoptotic effects of IFN-beta, and expression of the NLS mutant conferred resistance to IFN-beta. Apo2L/TRAIL expression and nuclear localization of IHPK2 are both required for the induction of apoptosis by IFN-beta in ovarian carcinoma.

Active Transport, Cell Nucleus↗

PubMed2003

Suppression of NF-kappa B survival signaling by nitrosylcobalamin sensitizes neoplasms to the anti-tumor effects of Apo2L/TRAIL.

We have previously demonstrated the anti-tumor activity of nitrosylcobalamin (NO-Cbl), an analog of vitamin B12 that delivers nitric oxide (NO) and increases the expression of tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) and its receptors in human tumors. The specific aim of this study was to examine whether NO-Cbl could sensitize drug-resistant melanomas to Apo2L/TRAIL. Antiproliferative effects of NO-Cbl and Apo2L/TRAIL were assessed in malignant melanomas and non-tumorigenic melanocyte and fibroblast cell lines. Athymic nude mice bearing human melanoma A375 xenografts were treated with NO-Cbl and Apo2L/TRAIL. Apoptosis was measured by TUNEL and confirmed by examining levels and activity of key mediators of apoptosis. The activation status of NF-kappa B was established by assaying DNA binding, luciferase reporter activity, the phosphorylation status of I kappa B alpha, and in vitro IKK activity. NO-Cbl sensitized Apo2L/TRAIL-resistant melanoma cell lines to growth inhibition by Apo2L/TRAIL but had minimal effect on normal cell lines. NO-Cbl and Apo2L/TRAIL exerted synergistic anti-tumor activity against A375 xenografts. Treatment with NO-Cbl followed by Apo2L/TRAIL induced apoptosis in Apo2L/TRAIL-resistant tumor cells, characterized by cleavage of caspase-3, caspase-8, and PARP. NO-Cbl inhibited IKK activation, characterized by decreased phosphorylation of I kappa B alpha and inhibition of NF-kappa B DNA binding activity. NO-Cbl suppressed Apo2L/TRAIL- and TNF-alpha-mediated activation of a transfected NF-kappa B-driven luciferase reporter. XIAP, an inhibitor of apoptosis, was inactivated by NO-Cbl. NO-Cbl treatment rendered Apo2L/TRAIL-resistant malignancies sensitive to the anti-tumor effects of Apo2L/TRAIL in vitro and in vivo. The use of NO-Cbl and Apo2L/TRAIL capitalizes on the tumor-specific properties of both agents and represents a promising anti-cancer combination.

Animals↗

PubMed2003

IFN-alpha2b and thalidomide synergistically inhibit tumor-induced angiogenesis.

Angiogenesis is an absolute requirement for tumor growth and metastasis. The purpose of this study was to evaluate the antiangiogenic activity of interferon-alpha2b (IFN-alpha2b) and thalidomide, as single agents and in combination. The murine dermis model was used to assess tumor-induced angiogenesis in nude mice. Human ACHN (renal), NIH-OVCAR-3 (ovarian), LNCaP (prostate), and SK-Mel-1 (melanoma) tumor cells were inoculated intradermally into the flanks of nude mice. IFN-alpha2b and thalidomide, administered daily, were effective inhibitors of angiogenesis induced by all four tumor types. The combination of IFN-alpha2b and thalidomide caused a synergistic decrease in mean vessel count in tumors that were resistant to the antiproliferative effects of IFN-alpha2b and thalidomide in vitro. This enhanced suppression of angiogenesis translated into synergistic antitumor activity in a xenograft model. Pegylated IFN-alpha (PEG-IFN-alpha2b) (10(6) U) administered once in 10 days was as effective as daily IFN-alpha2b treatment (10(6) U x 10 days). IFN-alpha2b and thalidomide have potentiated antiangiogenic activity when used in combination. A single dose of PEG-IFN-alpha2b (10(6) U) was as effective at suppressing vessel growth as an equivalent dose of IFN-alpha2b given daily for 10 days.

Angiogenesis Inhibitors↗

PubMed2002

Anticancer activity of sodium stibogluconate in synergy with IFNs.

Cancer cell resistance limits the efficacy of IFNs. In this study, we show that sodium stibogluconate (SSG) and IFN-alpha synergized to overcome IFN-alpha resistance in various human cancer cell lines in culture and eradicated IFN-alpha-refractory WM9 human melanoma tumors in nude mice with no obvious toxicity. SSG enhanced IFN-alpha-induced Stat1 tyrosine phosphorylation, inactivated intracellular SHP-1 and SHP-2 that negatively regulate IFN signaling, and induced cellular protein tyrosine phosphorylation in cancer cell lines. These effects are consistent with inactivation of phosphatases as the basis of SSG anticancer activity. Characterization of SSG by chromatography revealed that only selective compounds in SSG were effective protein tyrosine phosphatase inhibitors. These observations suggest the potential of SSG as a clinically usable protein tyrosine phosphatase inhibitor in cancer treatment and provide insights for developing phosphatase-targeted therapeutics.

Adjuvants, Immunologic↗

PubMed2002

Effects of interferon beta on transcobalamin II-receptor expression and antitumor activity of nitrosylcobalamin.

BACKGROUND: The ubiquitous plasma membrane transcobalamin II receptor (TC II-R) mediates uptake of cobalamin (Cbl; vitamin B12), an essential micronutrient. Tumors often require more Cbl than normal tissue, and increased Cbl uptake may result from increased TC II-R expression. To examine whether Cbl could therefore be used as a carrier molecule to target a chemotherapy drug, we tested an analogue of Cbl with nitric oxide as a ligand, nitrosylcobalamin (NO-Cbl). Because interferon beta (IFN-beta) has antitumor effects and increases expression of some membrane receptors, we examined whether it may enhance the effects of NO-Cbl. METHODS: Antiproliferative effects of NO-Cbl were assessed in 24 normal and cancer cell lines. Xenograft tumors of human ovarian cancer NIH-OVCAR-3 cells were established in athymic nude mice, and tumor growth was monitored after treatment with NO-Cbl and IFN-beta, both individually and concomitantly. TC II-R expression and apoptosis was monitored in vitro and in vivo. RNA protection assays and mitochondrial membrane potential assays were used to distinguish the extrinsic and intrinsic apoptotic pathways, respectively. RESULTS: Cancer cell lines were more sensitive to NO-Cbl (with ID(50)s [the dose that inhibits growth by 50%] as low as 2 microM) than normal cell lines (with ID(50)s of 85-135 microM). Single-agent NO-Cbl and IFN-beta treatment of NIH-OVCAR-3 xenografts induced tumor regression, whereas combination treatment induced tumor eradication. IFN-beta treatment increased TC II-R expression in vitro and uptake of [(57)Co]cobalamin in vivo. Compared with NIH-OVCAR-3 cells treated with NO-Cbl, cells treated with NO-Cbl and IFN-beta were more apoptotic and expressed higher mRNA levels of various apoptosis-associated genes. No changes in mitochondrial membrane potential were observed in cells treated with NO-Cbl. CONCLUSION: NO-Cbl inhibited tumor growth in vivo by activating the extrinsic apoptotic pathway. The increased expression of TC II-R induced by IFN-beta resulted in enhanced antitumor effects with NO-Cbl both in vitro and in vivo.

Animals↗

PubMed2002

MEKK1 plays a critical role in activating the transcription factor C/EBP-beta-dependent gene expression in response to IFN-gamma.

IFN-gamma induces a number of genes to up-regulate cellular responses by using specific transcription factors and the cognate elements. We recently discovered that CCAAT/enhancer-binding protein-beta (C/EBP-beta) induces gene transcription through an IFN-response element called gamma-IFN-activated transcriptional element (GATE). Using mutant cells, chemical inhibitors, and specific dominant negative inhibitors, we show that induction of GATE-driven gene expression depends on MEK1 (mitogen-activated protein kinase kinase/extracellular signal-regulated protein kinase kinase) and ERKs (extracellular signal-regulated protein kinases) but is independent of Raf-1. Interestingly in cells lacking the MEKK1 gene or expressing the dominant negative MEKK1, ERK activation, and GATE dependent gene expression is inhibited. A dominant negative MEKK1 blocks C/EBP-beta-driven gene expression stimulated by IFN-gamma. These studies describe an IFN-gamma-stimulated pathway that involves MEKK1-MEK1-ERK1/2 kinases to regulate C/EBP-beta-dependent gene expression.

Animals↗

PubMed2002

Mutational analysis of human thioredoxin reductase 1. Effects on p53-mediated gene expression and interferon and retinoic acid-induced cell death.

The interferon (IFN)-beta and all-trans-retinoic acid combination suppresses tumor growth by inducing apoptosis in several tumor cell lines. A genetic technique permitted the isolation of human thioredoxin reductase (TR) as a critical regulator of IFN/all-trans-retinoic acid-induced cell death. Our recent studies have shown that TR1:thioredoxin 1-regulated cell death is effected in part through the activation of p53-dependent responses. To understand its death regulatory function, we have performed a mutational analysis of TR. Human TR1 has three major structural domains, the FAD binding domain, the NADPH binding domain, and an interface domain (ID). Here, we show that the deletion of the C-terminal interface domain results in a constitutive activation of TR-dependent death responses and promotes p53-dependent gene expression. TR mutant without the ID still retains its dependence on thioredoxin for promoting these responses. Thus, our data suggest that TR-ID acts as a regulatory domain.

Base Sequence↗

PubMed2002

Inositol hexakisphosphate kinase 2 sensitizes ovarian carcinoma cells to multiple cancer therapeutics.

We recently identified inositol hexakisphosphate kinase 2 (IP6K2) as a positive regulator of apoptosis. Overexpression of IP6K2 enhances apoptosis induced by interferon-beta (IFN-beta) and cytotoxic agents in NIH-OVCAR-3 ovarian carcinoma cells. In this study, we contrast and compare IFN-beta and radiation-induced death, and show that IP6K2 expression sensitizes tumor cells. Unirradiated NIH-OVCAR-3 cells transfected with IP6K2 formed fewer colonies compared to unirradiated vector-expressing cells. IP6K2 overexpression caused increased radiosensitivity, evidenced by decreased colony forming units (CFU). Both IFN-beta and radiation induced caspase 8. IFN-beta, but not gamma-irradiation, induced TRAIL in NIH-OVCAR-3 cells. Gamma irradiation, but not IFN-beta, induced DR4 mRNA. Apoptotic effects of IFN-beta or gamma-irradiation were blocked by expression of a dominant negative mutant death receptor 5 (DR5Delta) or by Bcl-2. Caspase-8 mRNA induction was more pronounced in IP6K2-expressing cells compared to vector-expressing cells. These data suggest that overexpression of IP6K2 enhances sensitivity of some ovarian carcinomas to radiation and IFN-beta. IP6K2 may function to enhance the expression and/or function of caspase 8 and DR4 following cell injury. Both IFN-beta and gamma-irradiation induce apoptosis through the extrinsic, receptor-mediated pathway, IFN-beta through TRAIL, radiation through DR4, and both through caspase 8. The function of both death inducers is positively regulated by IP6K2.

Antineoplastic Agents↗

PubMed2002

Interferons as antiangiogenic agents.

Interferons (IFNs), pleiotropic cytokines that regulate antiviral, antitumor, apoptotic, and cellular immune responses, were the first endogenous antiangiogenic regulators identified. In a species-specific manner, IFNs inhibit secretion of such angiogenic factors as basic fibroblast growth factor from tumor cells. The antiangiogenic activity of IFNs is enhanced when they are combined with other antiangiogenic agents, such as tamoxifen and thalidomide.

Angiogenesis Inhibitors↗

PubMed2002

Thioredoxin reductase plays a critical role in IFN retinoid-mediated tumor-growth control in vivo.

The IFN and retinoic acid (RA) combination suppresses cell growth by inducing apoptosis in the cultured tumor cells. Using a genetic technique, we have isolated several "genes associated with retinoid-IFN-induced mortality" (GRIM) that participate in this death pathway. One such gene, GRIM-12, encodes the redox enzyme thioredoxin reductase (TR). Antisense-mediated inhibition of TR abrogates cell death. To test the in vivo relevance of TR for growth suppression, we have conducted the following study. A wild-type TR or a catalytically defective mutant were expressed in MCF-7 breast carcinoma cells and transplanted into athymic nude mice. These mice were treated with IFN-beta and all-trans RA combination. Tumors expressing the vector or wild-type TR were readily suppressed by the IFN/RA combination. In contrast, the tumors bearing a mutant TR were resistant to regression. We further show that markers of apoptosis are stimulated in the regressing tumors. These studies show a prominent role for TR in tumor-growth suppression.

Animals↗

PubMed2002

Pentamidine is an inhibitor of PRL phosphatases with anticancer activity.

The PRL family oncogenic phosphatases are attractive targets for developing inhibitors as anticancer therapeutics given their potentially pathogenic role in human malignancies. Herein we demonstrate that pentamidine, an anti-protozoa drug with an unknown mechanism of action, is an inhibitor of PRLs with anticancer potential. Pentamidine at its therapeutic doses inhibited recombinant PRL phosphatases in vitro and inactivated ectopically expressed PRLs in NIH3T3 transfectants with an effective duration more than 24 h after a pulse cell treatment. The drug had in vitro growth-inhibitory activity against human cancer cell lines that express the endogenous PRLs. Pentamidine at a tolerable dose markedly inhibited the growth of WM9 human melanoma tumors in nude mice coincident with the induction of tumor cell necrosis and is capable of inactivating ectopically expressed PRL-2 in the cancer cells. These observations suggest the potential of pentamidine in anticancer therapies and may provide a basis for developing novel PTPase-targeted therapeutics.

3T3 Cells↗

PubMedDate not supplied

N-terminally PEGylated human interferon-beta-1a with improved pharmacokinetic properties and in vivo efficacy in a melanoma angiogenesis model.

PEGylation of IFN-alpha has been used successfully to improve the pharmacokinetic properties and efficacy of the drug. To prepare a PEGylated form of human interferon-beta-1a (IFN-beta-1a) suitable for testing in vivo, we have synthesized 20 kDa mPEG-O-2-methylpropionaldehyde and used it to modify the N-terminal alpha-amino group of the cytokine. The PEGylated protein retained approximately 50% of the activity of the unmodified protein and had significantly improved pharmacokinetic properties following intravenous administration in rats. The clearance and volume of distribution at steady state were reduced approximately 30-fold and approximately 4-fold, respectively, resulting in a significant increase in systemic exposure as determined by the area under the curve. The elimination half-life of the PEGylated protein was approximately 13-fold greater than for the unmodified protein. The unmodified and PEGylated proteins were tested for their ability to inhibit the formation of radially oriented blood vessels entering the periphery of human SK-MEL-1 melanoma tumors in athymic nude homozygous (nu/nu) mice. In a single dose comparison study, administration of 1 x 10(6) units of unmodified IFN-beta-1a resulted in a 29% reduction in vessel number, while 1 x 10(6) units of PEGylated IFN-beta-1a resulted in a 58% reduction. Both treatments resulted in statistically significant reductions in mean vessel number as compared to the vehicle (control)-treated mice, with the PEGylated IFN-beta-1a-treated mice showing a statistically significantly greater reduction in mean vessel number as compared to the unmodified IFN-beta-1a-treated mice. In a multiple versus single dose comparison study, daily administration of 1 x 10(6) units of unmodified IFN-beta-1a for 9 days resulted in a 51% reduction in vessel number, while a single dose of 1 x 10(6) units of the PEGylated protein resulted in a 66% reduction. Both treatments resulted in statistically significant reductions in mean vessel number as compared to the vehicle-treated mice, with the PEGylated IFN-beta-1a-treated mice showing a statistically significantly greater reduction in mean vessel number as compared to the unmodified IFN-beta-1a-treated mice. Therefore, the improved pharmacokinetic properties of the modified protein translated into improved efficacy. Since unmodified IFN-beta is used for the treatment of multiple sclerosis and hepatitis C virus infection, a PEGylated form of the protein such as 20 kDa mPEG-O-2-methylpropionaldehyde-modified IFN-beta-1a may serve as a useful adjunct for the treatment of these diseases. In addition, the antiangiogenic effects of PEGylated IFN-beta-1a may be harnessed for the treatment of certain cancers, either as a sole agent or in combination with other antitumor drugs.

Aldehydes↗