Biomedical subjects

R J Walter

Publications and source records attributed to R J Walter.

At least 19 recordsLinked to original sources

PubMed2001

Newcastle disease virus therapy of human tumor xenografts: antitumor effects of local or systemic administration.

Previously we showed that a single local injection of the avian paramyxovirus Newcastle disease virus (NDV) strain 73-T caused long-lasting, complete tumor regression of human neuroblastoma and fibrosarcoma xenografts in athymic mice. Here we report the antitumor effects of NDV administered by either the intratumoral (IT) route to treat a variety of human carcinoma xenografts or by the systemic (intraperitoneal, IP) route to treat neuroblastoma xenografts (6.5-12 mm in diameter). For IT treatments, mice were randomized into treatment groups and given a single IT injection of NDV 73-T, vehicle (phosphate buffered saline, PBS), or UV-inactivated NDV. For systemic therapy, mice (n=18) with subcutaneous IMR-32 human neuroblastoma xenografts received IP injections of NDV (5 x 10(9) PFU). Significant tumor growth inhibition (77-96%) was seen for epidermoid (KB8-5-11), colon (SW620 and HT29), large cell lung (NCIH460), breast (SKBR3), prostate (PC3), and low passage colon (MM17387) carcinoma xenografts treated IT with NDV. In all cases, tumors treated IT with PBS or replication-incompetent, UV-inactivated NDV displayed rapid tumor growth. After a single IP injection of NDV, complete regression of IMR-32 neuroblastomas was observed in 9 of 12 mice without recurrence for the 3-9 month follow-up period. Six mice with recurrent neuroblastomas after one IP injection received one to three additional IP treatments with NDV. Three of these six mice showed complete regression without recurrence. These data show that: (1) NDV administered either IT or IP is an effective antitumor therapy in this system, (2) replication competency is necessary for maximal effect, and (3) multiple NDV doses can be more effective than a single dose. These studies provide further rationale for the preclinical study of NDV as an oncolytic agent.

Animals↗

PubMed2001

Resveratrol inhibits the proliferation of normal human keratinocytes in vitro.

Resveratrol, a phytoalexin found in grapes and other plants, is a potent antioxidant, anti-inflammatory, and antiproliferative agent that is thought to have chemopreventive properties with respect to carcinogenesis. However, the antiproliferative effects of resveratrol have been described primarily for cultured tumor cells and its effects on the proliferation of normal cells are not clear. We evaluated the viability and proliferation of cultured normal human keratinocytes (KCs) exposed to resveratrol (0.25-100 microM) for different lengths of time (5-72 h) by means of (3)H-thymidine incorporation, direct cell counts, and a tetrazolium-based formazan reaction. The first two methods indicated that resveratrol, even at low concentrations, induced a time-and concentration-dependent inhibition of KC proliferation. However, formazan production was actually increased at moderate resveratrol concentrations (10 microM) and diminished only at higher concentrations. Even brief exposure (5 h) of KCs to resveratrol resulted in a concentration-dependent elevation in formazan production. This was blocked by ionomycin but was not dependent on Ca(2+). We conclude that resveratrol, even at submicromolar concentrations, inhibits the proliferation of normal human KCs in vitro and, at higher concentrations (40-100 microM), is cytotoxic to these cells. J. Cell. Biochem. Suppl. 36: 55-62, 2001.

Antineoplastic Agents↗

PubMed2001

Long-term outcome of xenogenic dermal matrix implantation in immunocompetent rats.

BACKGROUND: Acellular dermal matrix (ADM) has been used successfully in the treatment of full-thickness skin injuries as an allogenic dermal substitute. To assess the efficacy of xenogenic ADM in such wounds, we examined the long-term wound healing and immunological responses to porcine ADM in a rat model. MATERIALS AND METHODS: Xenogenic and allogenic ADMs were produced by treating porcine (fresh or cryopreserved) or rat skin with dispase and Triton X-100. Full-thickness skin defects on the rat dorsum were implanted with porcine or rat ADMs and overlaid with split-thickness skin grafts (STSGs). Wounds were evaluated grossly and immunologically at 1, 6, and 12 months after surgery. RESULTS: Extensive wound contraction was seen in wounds implanted with porcine ADM, but healing was significantly (P < 0.01) better in the rat ADM or STSG groups at 6 and 12 months postsurgery. Sera obtained from porcine ADM-implanted rats reacted strongly with porcine ADM and specifically with the papillary dermis and basal lamina. One month postsurgery, extensive inflammation but few intact mast cells were seen in wounds implanted with porcine ADM and significant (P < 0.02) levels of residual porcine ADM were detectable immunologically. Little inflammation was evident in the STSG or rat ADM groups at any time. Significant lymphocyte proliferation (P < 0.05) occurred in the 6- and 12-month groups in response to porcine, but not rat, ADM. CONCLUSIONS: In wounds implanted with xenogenic ADM, a short-lived acute inflammatory response, long-lasting humoral and cell-mediated immune responses, and generally poor wound healing were observed.

Animals↗

PubMed2001

Use of porcine acellular dermal matrix as a dermal substitute in rats.

OBJECTIVE: To examine porcine acellular dermal matrix (ADM) as a xenogenic dermal substitute in a rat model. SUMMARY BACKGROUND DATA: Acellular dermal matrix has been used in the treatment of full-thickness skin injuries as an allogenic dermal substitute providing a stable wound base in human and animal studies. METHODS: Xenogenic and allogenic ADMs were produced by treating porcine or rat skin with Dispase and Triton X-100. Full-thickness skin defects (225 mm2) were created on the dorsum of rats (n = 29), porcine or rat ADMs were implanted in them, and these were overlain with ultrathin split-thickness skin grafts (STSGs). In two adjacent wounds, 0.005- or 0.017-inch-thick autografts were implanted. In other experiments, the antimicrobial agent used during ADM processing (azide or a mixture of antibiotics) and the orientation of the implanted ADM (papillary or reticular side of ADM facing the STSG) were studied. Grafts were evaluated grossly and histologically for 30 days after surgery. RESULTS: Significant wound contraction was seen at 14, 20, and 30 days after surgery in wounds receiving xenogenic ADM, allogenic ADM, and thin STSGs. Contraction of wounds containing xenogenic ADM was significantly greater than that of wounds containing allogenic ADM at 30 days after surgery. Graft take was poor in wounds containing xenogenic ADM and moderately good in those containing allogenic ADM. Wound healing was not significantly affected by the antimicrobial agent used during ADM preparation or by the ADM orientation. CONCLUSION: Dispase-Triton-treated allogenic ADM was useful as a dermal substitute in full-thickness skin defects, but healing with xenogenic ADM was poor.

Animals↗

PubMed2000

Female sex hormones modulate the function of LPS-treated macrophages.

PROBLEM: To study the effects of estradiol (E2) or progesterone on macrophage function in the presence of lipopolysaccharide (LPS). METHOD OF STUDY: Male rat peritoneal macrophages were treated in vitro with 0.1 microg/mL of LPS and E2 or progesterone. RESULTS: At 10(-2) ng/mL, E2 significantly (P < 0.05; n = 6) enhanced tumor necrosis factor (TNF) release by LPS-treated macrophages. TNF release was significantly (P < 0.05; n = 6) inhibited by 10(2) ng/mL or 10(3) ng/mL of E2 and by progesterone at less than 10(-3) ng/mL or greater than 10(-1) ng/mL. E2 (10(-4) and 10 ng/mL) and progesterone (10(-6)-10(-4) ng/mL and 10(2) ng/mL) each significantly (P < 0.05, n = 8) enhanced H2O2 release by LPS-treated macrophages. E2 ( < 10(-2) and > 10 ng/mL) and progesterone (10(-7)-10(4) ng/mL) each significantly inhibited (P< 0.05; n = 6) NO2- release by LPS-treated macrophages. CONCLUSIONS: Exposure to LPS tended to diminish the effects of E2 and to enhance the effects of progesterone on the parameters determined here. Such LPS-associated alterations in the dose-response profile of macrophages to female sex hormones may contribute to gender-related differences in the immune response under normal and pathological conditions.

Animals↗

PubMed1999

Differential regulation of mitogen-activated protein kinases by microtubule-binding agents in human breast cancer cells.

Drug design targeted at microtubules has led to the advent of some potent anti-cancer drugs. In the present study, we demonstrated that microtubule-binding agents (MBAs) taxol and colchicine induced immediate early gene (c-jun and ATF3) expression, cell cycle arrest, and apoptosis in the human breast cancer cell line MCF-7. To elucidate the signal transduction pathways that mediate such biological activities of MBAs, we studied the involvement of mitogen-activated protein (MAP) kinases. Treatment with taxol, colchicine, or other MBAs (vincristine, podophyllotoxin, nocodazole) stimulated the activity of c-jun N-terminal kinase 1 (JNK1) in MCF-7 cells. In contrast, p38 was activated only by taxol and none of the MBAs changed the activity of extracellular signal-regulated protein kinase 2 (ERK2). Activation of JNK1 or p38 by MBAs occurred subsequent to the morphological changes in the microtubule cytoskeleton induced by these compounds. Furthermore, baccatine III and beta-lumicolchicine, inactive analogs of taxol and colchicine, respectively, did not activate JNKI or p38. These results suggest that interactions between microtubules and MBAs are essential for the activation of these kinases. Pretreatment with the antioxidants N-acetyl-L-cysteine (NAC), ascorbic acid or vitamin E, blocked H2O2- or doxorubicin-induced JNKI activity, but had no effect on JNKI activation by MBAs, excluding a role for oxidative stress. However, BAPTA/AM, a specific intracellular Ca2+ chelator, attenuated JNK1 activation by taxol but not by colchicine, and had no effect on microtubule changes induced by taxol. Thus, stabilization or depolymerization of microtubules may regulate JNK1 activity via distinct downstream signaling pathways. The differential activation of MAP kinases opens up a new avenue for addressing the mechanism of action of antimicrotubule drugs.

Apoptosis↗

PubMed1998

Characterization of acellular dermal matrices (ADMs) prepared by two different methods.

The efficacy of acellular dermal matrix (ADM) in the treatment of full-thickness skin injuries as a dermal substitute depends on its low antigenicity, capacity for rapid vascularization, and stability as a dermal template. These properties will be determined largely by the final composition of the ADM. We have treated human skin with either Dispase followed by Triton X-100 detergent or NaCl followed by SDS detergent, cryosectioned the resulting ADMs, and then characterized them immunohistochemically. Staining for cell-associated antigens (HLA-ABC, HLA-DR, vimentin, desmin, talin), extracellular matrix components (chondroitin sulfate, fibronectin, laminin, vitronectin, hyaluronic acid), elastin, and collagen type VII was dramatically reduced or absent from ADMs prepared by both methods. However, significant amounts of elastin, keratan sulfate, laminin, and collagen types III and IV were still observed in both ADMs. Both methods of ADM preparation resulted in extensive extraction of both cellular and extracellular components of the skin but retention of the basic dermal architecture. In general, ADM prepared by the NaCl-SDS method retained larger amounts of each antigen than did that prepared by the Dispase-Triton method. This was most evident for laminin and type VII collagen but larger amounts of type IV collagen, fibronectin, desmin, elastin, and HLA-DR were also evident in the NaCl-SDS ADM.

Cytoskeletal Proteins↗

PubMed1998

Effect of an inhibitor of glucosylceramide synthesis on cultured human keratinocytes.

Glucosylceramide (GlcCer) is a major glycosphingolipid component of epidermis, which is thought to be related to the barrier function of skin permeability. However, the role of glycosphingolipids in keratinocyte growth and differentiation has not been fully clarified. It has been reported that D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), an inhibitor of GlcCer synthase (EC 2.4.1.80), depletes cells of glycosphingolipids. This inhibitor has been used as a tool for elucidating their functions. In the present study, the effect of PDMP on cultured normal human keratinocytes was investigated. The cells were treated with various concentrations of PDMP. Forty-eight hours later cell growth, thymidine incorporation, and lipid content were studied. The cell growth and the incorporation of thymidine into cells were inhibited by PDMP in a dose dependent manner. The synthesis of GlcCer was strongly inhibited by PDMP treatment, whereas no significant changes in ceramide level were observed. We concluded that GlcCer in epidermis may play an important role in regulating epidermal growth and suggested that PDMP may be beneficial for treating proliferative skin disorders in the future.

Adult↗

PubMed1997

Binding and internalization of anti-sarcoma IgG and IgM antibodies.

A variety of monoclonal antibodies directed against tumor cell surface antigens have been employed for tumor detection and delivery of toxins and radioisotopes to tumors in situ. The sequence of events following antibody binding to tumor cells may be critical to the success or failure of tumor imaging or therapy. Using indirect immunofluorescence, we have examined the binding and internalization of two different monoclonal antibodies (19-24 and MFH 4.10) by HT-1080, a cultured human sarcoma cell line. MAb 19-24 (IgG1) and MAb MFH 4.10 (IgM) are directed against surface antigens on cells from human malignant fibrous histiocytoma (MFH). For both of these antibodies, the initial binding on the surface of HT-1080 cells at 4 degrees C was uniform. After binding secondary fluorescent antibody, monoclonal antibodies underwent rapid internalization at 37 degrees C. Surface-bound antigen-antibody complexes were completely cleared from the cell surface in 30-60 min. In the absence of secondary fluorescent antibody, MAb 19-24 remained bound to the cell surface at 37 degrees C for up to 20 hr without being released or internalized. However, under these same conditions MAb MFH 4.10 was internalized completely within 30 min by HT-1080 cells and did not subsequently return to the cell surface. Such differences in the mechanisms of binding and uptake for these two antibodies may have significant implications for their future clinical or therapeutic uses.

Animals↗

PubMed1997

60-Hz electric fields inhibit protein kinase C activity and multidrug resistance gene (MDR1) up-regulation.

Sixty-hertz electric fields have been shown to affect biological systems in a variety of ways, but the mechanisms by which electric fields influence cell function remain uncertain. We have investigated the effects of electric fields on cellular protein kinase C (PKC) activity and on the regulation of the multidrug resistance gene (MDR1), which is responsible for a major form of drug resistance in cancer. We found that exposure of H9 human leukemia cells to 60-Hz sinusoidal electric fields (330 or 750 mV/cm for 60 min) resulted in significantly decreased PKC activity in the cytosolic fraction, whereas electric fields at higher (1250 and 3000 mV/cm) or lower (10 mV/cm) intensities had no effect on PKC activity. Exposure of these cells to electric fields (330 or 750 mV/cm for 17 h) inhibited up-regulation of MDR1 expression by treatment with 25 microM 1-beta-D-arabinofuranosylcytosine (AraC). Again, lower or higher field strengths had little or no effect on the levels of AraC-induced MDR1 mRNA. Similarly, exposure of intact cells to staurosporine (100 nM), a potent PKC inhibitor, significantly reduced cytosolic PKC activity, but not that of the particulate fraction. Staurosporine also prevented AraC-induced MDR1 overexpression. These data show that intermediate-strength electric fields inhibit cytosolic PKC and suggest that electric fields and pharmacological inhibitors of PKC, such as staurosporine, affect cytosolic PKC activity and AraC-induced MDR1 overexpression through related mechanisms. Our findings also suggest the possible utility of 60-Hz electric fields for modulating multidrug resistance in tumor cells.

Cytarabine↗

PubMed1996

Protein kinase C activity is altered in HL60 cells exposed to 60 Hz AC electric fields.

We examined the effects of electric fields (EFs) on the activity and subcellular distribution of protein kinase C (PKC) of living HL60 cells. Sixty Hertz AC sinusoidal EFs (1.5-1,000 mV/cm p-p) were applied for 1 h to cells (10(7)/ml) in Teflon chambers at 37 degrees C in the presence or absence of 2 microM phorbol 12-myristate 13-acetate (PMA). PMA stimulation alone evoked intracellular translocation of PKC from the cytosolic to particulate fractions. In cells that were exposed to EFs (100-1,000 mV/cm) without PMA, a loss of PKC activity from the cytosol, but no concomitant rise in particulate PKC activity, was observed. In the presence of PMA, EFs (33-330 mV/cm) also accentuated the expected loss of PKC activity from the cytosol and augmented the rise in PKC activity in the particulate fraction. These data show that EFs alone or combined with PMA promote down-regulation of cytosolic PKC activity similar to that evoked by mitogens and tumor promoters but that it does not elicit the concomitant rise in particulate activity seen with those agents.

Carcinogens↗

PubMed1996

Dispase/detergent treated dermal matrix as a dermal substitute.

A method for preparing acellular allogeneic dermal matrix (ADM) and its effectiveness as a dermal substitute are described. Treatment of rat skin with Dispase followed by Triton X-100 completely removed cellular components from the dermis. Subcutaneously implanted ADM evoked no immunological reaction and 20 weeks after implantation, the size of the implanted ADM was reduced to about 60 per cent of its original area. ADM became completely vascularized within 2 weeks after implantation into full thickness skin defects in the rat and inhibited extensive wound contracture. A second layer of ADM placed onto the implanted ADM served as an excellent dressing, providing mechanical protection and permitting vascularization of the underlying implant. Onlay skin autografts placed onto vascularized allogeneic ADM showed good survival when the skin was grafted more than 1 week after ADM implantation. Dispase/detergent treated ADM derived from animal or human skin may be useful in full thickness skin defects providing a vascularized bed for subsequent epidermal coverage.

Animals↗

PubMed1996

Steroid sex hormones and macrophage function: regulation of chemiluminescence and phagocytosis.

PROBLEM: Female sex hormones modulate a variety of humoral and cell-mediated immunologic functions. In this study, the effects of estrogen, progesterone, and testosterone on the chemiluminescence (CL) response and phagocytic ability of male rat peritoneal macrophages (M luminal diameter) were examined. METHOD: In M luminal diameter pretreated with 10(-2) ng/ml of 17 beta-estradiol (E2) for 20 hours, the CL generated in response to phorbol myristate acetate (PMA), 1,2-dioctanoyl-rac-glycerol (C8:0), or opsonized zymosan (OZ) was significantly increased by 135%, 140%, and 136% of control values, respectively. In addition, M luminal diameter treated with 10(-5) ng/ml or 10 ng/ml of E2 exhibited a significantly greater PMA- or OZ-stimulated CL response than did untreated controls. RESULTS: At 10(-2) ng/ml, progesterone enhanced and testosterone reduced the CL response, but these changes were not statistically significant. In time course studies, the PMA-stimulated CL response of M luminal diameter treated with 10(-2) ng/ml of E2 or progesterone for 5 h was significantly less than that of the untreated group. In the presence of endotoxin (12 pg/ml), the CL response in M luminal diameter treated with E2 or testosterone was significantly depressed as compared to untreated controls. Phagocytosis of opsonized sheep erythrocytes also was significantly enhanced (140% to 190% of control) when M luminal diameter were pretreated with 10(-12) M to 10(-8) M of either E2 or progesterone. CONCLUSIONS: These findings suggest that, at physiological concentrations, E2 is capable of modulating both CL generation and phagocytic uptake by M luminal diameter in a manner not shared by other steroid hormones.

Animals↗

PubMed1995

Somatostatin and macrophage function: modulation of hydrogen peroxide, nitric oxide and tumor necrosis factor release.

Recent studies have shown that somatostatin modulates lymphocyte function, but the effects of somatostatin on macrophage function are not clearly defined. In the present study, peritoneal macrophages (Mluminal diameter) obtained from male rats were treated in vitro with somatostatin or octreotide and their effects on the release of hydrogen peroxide (H2O2), nitrite, and tumor necrosis factor (TNF) determined. Macrophages treated with somatostatin (10(-9) M to 10(-7) M) or octreotide (10(-8) M and 10(-7) M) released significantly greater amounts of PMA-stimulated H2O2 than did the untreated controls. In addition, 10(-9) M of somatostatin significantly enhanced PMA-stimulated H2O2 release by LPS-treated Mluminal diameter. Octreotide had no effect on H2O2 release by LPS-treated Mluminal diameter. At concentrations of 10(-14) M, 10(-13) M, or greater than 10(-8) M, somatostatin or octreotide suppressed nitrite release by Mluminal diameter. Somatostatin or octreotide did not affect nitrite release by LPS-treated Mluminal diameter. On the other hand, Mluminal diameter treated with 10(-11) M of somatostatin or octreotide released greater amounts of TNF than did the untreated controls. In contrast, TNF release by Mluminal diameter treated with 10(-9) M to 10(-5) M of somatostatin or 10(-7) M to 10(-5) M of octreotide was less than that of the controls. Anti-TNF antibody (1:1000) caused a reduction in the release of H2O2 and nitrite. These findings demonstrate that somatostatin and octreotide modulate the release of H2O2, nitric oxide, and TNF by Mluminal diameter depending on the concentration of hormones used.

Animals↗

PubMed1995

Steroid sex hormones regulate the release of tumor necrosis factor by macrophages.

Generally, females have been found to have a heightened immune response and a concomitantly higher incidence of autoimmune diseases compared to males. We have used male rat peritoneal macrophages (M phi) to study the effect of female sex hormones on tumor necrosis factor (TNF) release. The amount of TNF released by macrophages (M phi) exposed to 10(-2) and 10(-3) ng/ml of 17 beta-estradiol (E2) (35.1 +/- 7.3 and 23.2 +/- 2.5 units/ml, respectively) was significantly (P < 0.05; n = 9) greater than that released by untreated M phi. Progesterone (P) also significantly (P < 0.05; n = 8) stimulated a maximal TNF release (24.4 +/- 2.8 units/ml TNF) at 10(-2) ng/ml. On the other hand, the amount of TNF released by M phi exposed to E2 or P at concentrations greater than 10(-1) or less than 10(-4) ng/ml was significantly (P < 0.05) reduced compared to untreated controls. In contrast, testosterone did not significantly affect TNF release at any concentration. Within the physiological range of E2 and P concentrations, TNF release from M phi is finely regulated and dramatically affected by relatively small changes in hormone concentrations.

Animals↗

PubMed1994

Complete regression of human fibrosarcoma xenografts after local Newcastle disease virus therapy.

We have recently demonstrated that a single local injection of the avian pathogen Newcastle disease virus (NDV; strain 73-T) causes complete regression of human neuroblastoma xenografts in athymic mice (R. M. Lorence, K. W. Reichard, B. B. Katubig, H. M. Reyes, A. Phuangsab, B. R. Mitchell, C. J. Cascino, R. J. Walter, and M. E. Peeples. J. Natl. Cancer Inst., 86: 1228-1233, 1994). In this report, we tried to determine if this in vivo antineoplastic effect of NDV extends to human sarcomas. Athymic mice with s.c. HT1080 fibrosarcoma xenografts (7-14 mm) were randomly divided into two groups and treated i.t. with a single injection of either 10(7) plaque-forming units of NDV or phosphate-buffered saline. Complete tumor regression occurred in 8 of 10 mice treated with NDV while unabated tumor growth occurred in all 9 mice treated with phosphate-buffered saline (P < 0.001). To determine if complete tumor regression was long lasting, the 8 mice were monitored for 1 year, during which time no tumor recurred. To test the antitumor effects of NDV on tumors derived from a fresh human sarcoma, a similar experiment was performed in athymic mice using TH15145 synovial sarcoma xenografts at their first and second passages. Of 9 mice with TH15145 xenografts, a single i.t. injection of NDV (10(7) plaque-forming units) caused complete regression of 3 tumors and > 80% regression in 3 more tumors. In contrast, tumors in all 5 mice treated with phosphate-buffered saline exhibited unabated growth (P < 0.03 for > 80% tumor regression). Since HT1080 fibrosarcoma cells express the N-ras oncogene, we explored the effects that transfection of this oncogene has on the sensitivity to NDV. Cultured human fibroblasts that were made tumorigenic following N-ras-transfection were found to be 1000-fold more sensitive to NDV than normal fibroblasts in a cytotoxicity assay. Oncogene expression by the HT1080 fibrosarcoma may therefore contribute to the long-lasting complete regression of this sarcoma following a single local injection of NDV.

Animals↗

PubMed1994

Complete regression of human neuroblastoma xenografts in athymic mice after local Newcastle disease virus therapy.

BACKGROUND: Neuroblastoma is the most common pediatric extra-cranial solid cancer. Using conventional therapies, children older than 1 year of age with advanced neuroblastoma have a poor prognosis. The development of new approaches for treating such children with neuroblastoma continues to be one of the most important goals today in pediatric oncology. Despite numerous anecdotal reports of human tumor regression during viral infections, the use of viruses to directly lyse neuroblastoma cells has never been reported as a potential therapy. Newcastle disease virus (NDV) has been shown to replicate in and kill cultured human and rat neuroblastoma cells but not normal human fibroblasts. PURPOSE: Our purpose was to determine if this selective killing of human neuroblastoma (IMR-32) cells is maintained during the in vivo treatment of established tumors. METHODS: Two experiments were performed using NDV strain 73-T. Athymic mice with subcutaneous IMR-32 human neuroblastoma xenografts (6-12 mm) were treated intralesionally with live NDV, UV-inactivated NDV, or phosphate-buffered saline (PBS). To study virus replication in situ, mice were given intratumoral or intramuscular injections of NDV. These mice were then killed at various times, and the amount of infectious virus present in tumor or muscle was determined. RESULTS: After one injection of live NDV, 17 of 18 tumors regressed completely, whereas rapid tumor growth occurred in all 18 mice treated with PBS and in all nine mice treated with UV-inactivated NDV (P < .0001). The one tumor that showed only a partial response to a single injection regressed completely after a second NDV treatment. Six months following virus-induced regression, only one tumor had recurred. No significant acute or chronic side effects of live NDV were noted in athymic mice given doses up to 500 times that used in this study. Virus levels increased more than 80-fold between 5 and 24 hours in virus-injected tumors (P < .04), while no infectious virus was produced in NDV-injected muscle tissue. CONCLUSIONS: NDV 73-T appears to replicate selectively in human IMR-32 neuroblastoma xenografts, leading directly to a potent antitumor effect as demonstrated by long-lasting, complete tumor regression occurring after a single local injection of virus. IMPLICATION: These experiments may provide an important step in the development of new therapeutic approaches to challenging cancers such as neuroblastoma.

Animals↗

PubMed1994

Spatial association of HIV-1 tat protein and the nucleolar transport protein B23 in stably transfected Jurkat T-cells.

The human immunodeficiency virus (HIV-1) encodes a transactivator protein, the product of the tat gene (tat), which is essential for virus replication. In this study, immunogold electron microscopy was used in a stably transfected Jurkat T-cell line that constitutively expresses HIV-1 tat protein to determine the subcellular and intranuclear distribution of tat protein. Two nucleocytoplasmic shuttle proteins C23/nucleolin and B23 and a third nucleolar antigen that was detected by monoclonal antibody MAb 1277 were also examined. In addition, spatial association of C23 and B23 with tat protein at several subcellular locations was examined in dual-labeling experiments. The results showed that tat protein was found in both the cytoplasm and nucleus but was especially prominent within the dense fibrillar and granular components of the nucleolus. There was little labeling of tat protein in the fibrillar centers where MAb 1277 antigen was localized at a comparatively high level. The subcellular and intranucleolar distribution of tat protein was virtually identical to the pattern seen with C23 and B23. Although the intranuclear distributions of C23, B23 and tat protein were very similar, C23 and tat protein were seldom spatially associated. In contrast, B23 and tat protein were frequently spatially associated in the nucleolus and in several other subcellular locations including the cytoplasm, nucleoplasm, at the nuclear envelope and plasma membrane. While a physical association was not directly demonstrated in this study, the spatial association between B23 and tat protein strongly suggest that such an association may exist.

Animals↗