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Biomedical subjects

E Kohn

Publications and source records attributed to E Kohn.

At least 19 recordsLinked to original sources
PubMed2000

CAIR-1/BAG-3 forms an EGF-regulated ternary complex with phospholipase C-gamma and Hsp70/Hsc70.

CAIR-1/BAG-3 forms an EGF-regulated ternary complex with Hsp70/Hsc70 and latent phospholipase C-gamma (PLC-gamma). The expression of CAIR-1, CAI stressed-1, was induced in A2058 human melanoma cells by continuous exposure to CAI, an inhibitor of nonvoltage-gated calcium influx. CAIR-1 sequence is identical, save 2 amino acids, to BAG-3 also cloned recently as Bis, a member of the bcl-2-associated athanogene family. We show that CAIR-1/BAG-3 binds to Hsp70/Hsc70 in intact cells and this binding is increased by short term exposure to CAI (P<0.007). CAIR-1/BAG-3 is phosphorylated in vivo in the absence of stimulation. Basal phosphorylation is inhibited by treatment with d-erythrosphingosine (d-ES), a broad inhibitor of the protein kinase C family. CAIR-1/BAG-3 contains several PXXP SH3 binding domains leading to the hypothesis that it is a partner protein of phospholipase C-gamma. PLC-gamma is bound to CAIR-1/BAG-3 in unstimulated cells. It is increased by CAI or d-ES (P=0.05) treatment, and abrogated by EGF (r2=0.99); d-ES treatment blocks the EGF-mediated dissociation. We show that CAIR-1/BAG-3 binds to PLC-gamma and Hsp70/Hsc70 through separate and distinct domains. Hsp70/Hsc70 binds to the BAG domain of BAGs-1 and -3. CAIR-1/BAG-3 from control and EGF-treated cell lysates bound selectively to the SH3 domain of PLC-gamma, but not its N-SH2 or C-SH2 domains. Confirming the SH3 interaction, PLC-gamma was pulled down by CAIR-1/BAG-3 PXXP-GST fusions, but GST-PXXP constructs confronted with lysates from EGF-treated cells did not bind PLC-gamma as was seen in intact cells. Hsp70/Hsc70 was brought down by the PLC-gamma SH3 construct equally from native and EGF-treated cells, but did not bind the PXXP construct under either condition. We propose that CAIR-1/BAG-3 may act as a multifunctional signaling protein linking the Hsp70/Hsc70 pathway with those necessary for activation of the EGF receptor tyrosine kinase signaling pathways.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Endothelial monocyte activating polypeptide II induces endothelial cell apoptosis and may inhibit tumor angiogenesis.

Endothelial monocyte activating polypeptide II (EMAP-II) is a tumor-derived cytokine with potent effects on endothelial cells in vitro and in vivo including upregulation of tissue factor and the sensitization of human melanoma to systemic TNF treatment via its effects on the tumor vasculature. We investigated the effects of EMAP-II on tumor growth, angiogenesis, vasculogenesis, and apoptosis. EMAP-II inhibited endothelial cell proliferation, vasculogenesis, and neovessel formation. In vivo growth of human melanoma lines expressing high amounts of EMAP-II demonstrated slower growth, smaller tumors, and increased amounts of tumor necrosis than those expressing lower amounts of EMAP-II. EMAP-II induced endothelial-cell-specific apoptosis via a pathway that includes upregulation of the Fas-associated death domain and downregulation of Bcl-2. EMAP-II appears to have important effects on angiogenesis and may play a role in regulating tumor vascular growth.

3T3 Cells↗
PubMed1999

Synchronous inflammatory breast cancer and advanced ovarian carcinoma: a case with prolonged disease-free survival.

Despite the known association of these malignancies, the incidence of a synchronous presentation of breast and ovarian cancer is low, and the current literature does not address an approach to this clinical problem directly. We report a greater than 2.5 year disease-free survival in a patient treated for synchronous stage IIIB inflammatory breast cancer and stage IIIC epithelial ovarian cancer. The prolonged disease-free survival in our case may provide some guidance in this unusual clinical situation.

Breast Neoplasms↗
PubMed1997

Pharmacokinetics of elemental platinum (ultrafiltrate and total) after a thirty minute intravenous infusion of ormaplatin.

Preclinical data suggest that ormaplatin (tetrachloro-(dl-trans)-1, 2-diamminocyclohexaneplatinum) has substantial activity in cisplatin-resistant tumor models and may be less nephrotoxic than cisplatin. Based on these data we initiated a phase I clinical trial in patients with refractory metastatic cancer. This report characterizes the pharmacokinetic profile of both the total plasma concentrations of elemental platinum and the unbound ultrafiltrate concentrations of elemental platinum, following a 30 min intravenous infusion of ormaplatin. Platinum concentrations were determined by AAS, and pharmacokinetic parameters for both the total plasma concentration and the ultrafiltrate concentration of elemental platinum were determined using both compartmental and noncompartmental methods. Twenty-eight patients (14 males and 14 females; median age, 58) received ormaplatin. There was a linear relationship between Cmax and dose (r2 = 0.945) and AUC and dose (r2 = 0.976). Ormaplatin is more accurately described by a two-compartment model than by a one-compartment model. The distribution half-life (t1/2 alpha) was 0.3 h and the terminal half-life (t1/2 beta) was 39.1 h. The volume of the central compartment (V) was 68.6 L and the volume of distribution at steady state (Vdss) was 183 L. Like total plasma platinum, unbound platinum is also best characterized by a two-compartment model. The elimination of free platinum is also biphasic with a distribution half-life (t1/2 alpha) of 0.3 h and a terminal half-life (t1/2 beta) of 19.3 h. The mean volume of the central compartment (V) was 200.5 L, and the mean volume of distribution at steady state (Vdss) was 560.5 L. Clinical development of ormaplatin has been terminated due to increased frequency of neurological complications noted over other platinum agents; however, the pharmacokinetics are, in general, similar to those of other clinically used platinum compounds.

Adult↗
PubMed1996

The relationship between borderline ovarian tumors and epithelial ovarian carcinoma: epidemiologic, pathologic, and molecular aspects.

Borderline ovarian tumors (BOT) are a low-grade form of ovarian malignancy with significantly less aggressive behavior than classical epithelial ovarian carcinoma (EOC). Yet, a subset of these tumors can progress and be lethal. Prognostic factors related to the development of BOT are similar to those for EOC. BOT with aneuploid DNA content have a worse prognosis; this trend is similar to that found in EOC. Patterns of loss of heterozygosity of some chromosomal abnormalities suggest that some, but not all BOT may evolve into more invasive tumors. Molecular biology has provided some clues to the pathogenesis of this entity. Increasing frequency of K-ras mutations are associated with EOC compared to BOT or benign lesions of the ovary. Platelet-derived growth factor and PDGF-alpha receptor are overexpressed in some BOT and EOC, but not in benign tumors or normal ovaries. These genetic markers suggest a closer relationship between a subset of BOT and invasive EOC. Further analysis of genetic abnormalities may delineate the relationship between BOT and EOC better, and will hopefully lead to a unifying hypothesis as to the origin of these important ovarian lesions.

Carcinoma↗
PubMed1996

A phase I study of paclitaxel and cyclophosphamide in recurrent adenocarcinoma of the ovary.

We have conducted a disease specific phase I study of paclitaxel and cyclophosphamide in recurrent adenocarcinoma of the ovary. This was done to take advantage of the cellular and molecular synergism between paclitaxel and DNA-damaging agents, with the hope of avoiding paclitaxel-cisplatin toxicities. Paclitaxel was given as a 24-hr CIVI, after which cyclophosphamide was given as a 60-min infusion. Cycles of therapy were repeated every 3 weeks; and granulocyte colony-simulating factor (G-CSF) was given in a "flexible" dosing fashion. Starting doses were 170 mg/m2 paclitaxel and 750 mg/m2 cyclophosphamide. Dose-limiting toxicity (DLT) was seen at the doses of 250 mg/m2 paclitaxel and 1250 mg/m2 cyclophosphamide. DLT was cumulative thrombocytopenia. There were six nonhematologic grade 3 or 4 toxicities experienced in the study. Eleven of 20 evaluable patients (55%) have achieved an objective response (4 CCR;7 PR). Three of four CCRs were confirmed by negative findings at peritoneoscopy. The median number of prior therapies was 2 (range 1-4) and 17 individuals had platinum-refractory disease. We conclude that paclitaxel followed by cyclophosphamide is an active combination in recurrent ovarian cancer and that further study is needed to determine if this combination is truly better than paclitaxel alone.

Adenocarcinoma↗
PubMed1996

Paclitaxel dose intensity.

Paclitaxel is effective in the treatment of cancer of the ovary and cancer of the breast, as well as other malignancies. We have analyzed available phase II data in these two diseases, to assess the possibility that paclitaxel dose intensity may be important in the induction of disease response. When analyzed by the methods developed by Hrynuik and Levin, available data suggest that the relationship between objective disease response and paclitaxel dose intensity in recurrent cancer of the ovary is strongly statistically significant with a two-sided p value of 0.022. Available data suggest that the relationship in breast cancer is even stronger, with a two-sided p value of 0.004. In both diseases, optimal results have been observed at the dose schedule of 250 mg/m2/21 days, given as a 24 hour IV infusion. We have also performed an analysis comparing the only two prospective randomized studies that examined the potential role of dose intensity for this drug in cancer of the ovary. At 135 mg/m2/21 days, the objective response rate was 13.2%; and at 250 mg/m2/21 days, the objective response rate was 35.9%. The response rate seen at the intermediate dose of 175 were intermediate to 135 and 250; and linear regression analysis shows a correlation coefficient for these data of 0.946. Since flexible cytokine support may be essential in maintaining paclitaxel dose intensity, we have also discussed this approach as well as the paclitaxel dosing strategy that is associated with optimal clinical results in recurrent cancer of the ovary.

Antineoplastic Agents, Phytogenic↗
PubMed1994

Calcium-mediated signal transduction: biology, biochemistry, and therapy.

The process of proliferation, invasion and metastasis is a complex one which involves both the autonomy of the malignant cells and their interaction with the cellular and extracellular environments. The way in which the tumor cells respond to cellular and extracellular stimuli is regulated through transduction of those signals and translation into cellular activity. Transmembrane signal transduction involves three major categories of events: ion channel activation, transmission through guanine nucleotide binding protein intermediates with production of second messengers, and phosphorylation events. A frequent common denominator of these different pathways is a cellular calcium homeostasis. Calcium may be both a result of and a regulator of many of these signal transduction pathways and has been shown to have a role in the regulation of proliferation, invasion, and metastatic potential. The understanding and application of the basic tenets of these pathways to tumor cell proliferation, invasion, and metastases opens a new target for therapeutic intervention. We have identified a novel agent, CAI, which through inhibition of stimulated calcium influx inhibits proliferation and migration in vitro, and growth and dissemination in human cancer xenografts in vivo. CAI offers a new approach to cancer therapy, signal transduction therapy.

Animals↗
PubMed1993

Aging issues in invasion and metastasis. Fertile ground for investigation.

BACKGROUND: Ovarian cancer is a disease of predominantly older women and one in which metastases occur early and extensively. The unusual pattern of local metastasis is fertile ground for laboratory and clinical investigation. METHODS: Tools are now available with which to study the complex cascade of invasion and metastasis as it underlies invasive ovarian cancer. The metastatic cascade involves five repetitive steps: angiogenesis, adhesion to the vascular basement membrane, local proteolysis, migration into and out of the vasculature, and proliferation at the secondary sites. Both in vivo and in vitro models of ovarian cancer are available; however, there are no systems targeted to understanding age-related differences in ovarian cancer biology. RESULTS: Progress in investigation of the biology of ovarian cancer has led to new diagnostic and therapeutic leads, including the use of adhesion receptors, protease secretion, and stimulation of tumor cell migration as potential markers and the identification of a new anti-cancer agent, CAI (NSC609974). CONCLUSIONS: CAI inhibits signal transduction pathways important in the regulation and activation of metastasis and proliferation. A phase I study has begun accrual at the National Cancer Institute; the protocol will contain no upper age limit.

Aging↗
PubMed1993

Age does not influence taxol dose intensity in recurrent carcinoma of the ovary.

BACKGROUND: In the treatment of advanced-stage ovarian cancer, it is common practice to treat elderly patients in a less aggressive fashion than young patients. This approach is based on the notion that age is associated with poor patient tolerance to aggressive chemotherapy. Relatively little data exist to support this contention. The most exciting new chemotherapy agent to be developed in the last 10 years is taxol, a diterpeniod derivative of the Northwestern yew Taxus brevifolia. METHODS: The ability to administer dose-intensive taxol to adult patients with recurrent ovarian cancer was assessed retrospectively, and the question was asked whether the administered dose intensity of taxol was unfavorably influenced by age. Forty-eight patients with recurrent ovarian carcinoma received taxol at an initial dose of 250 mg/m2 every 3 weeks. Age in this cohort ranged from 26 to 74 years, with a median of 55. Twenty-nine percent (14 of 48) of the patients treated were 61 years of age or greater. Criteria for administration of taxol included a creatinine clearance of > 45 ml/minute, minimal abnormalities in liver function tests, good performance status, and the absence of substantial comorbid disease. RESULTS: Elderly patients in this cohort (age > 60 years) did not differ from younger patients with respect to administered dose intensity, number of cycles of therapy administered, or the occurrence of serious or mild toxicities.

Adult↗
PubMed1993

The absence of cumulative bone marrow toxicity in patients with recurrent adenocarcinoma of the ovary receiving dose-intense taxol and granulocyte colony stimulating factor.

Forty-eight patients with recurrent adenocarcinoma of the ovary were treated with taxol and granulocyte colony stimulating factor (G-CSF), with a target taxol dose intensity of 250 mg/m2 every 3 weeks (83.3 mg/m2/week). We have assessed the patterns of granulocyte and platelet toxicity seen in this cohort. Individual patients received up to nine cycles of therapy. Criteria for entry onto protocol included good end organ function, good performance status and the absence of substantial co-morbid disease. Mean taxol dose intensity was 79.0 mg/m2/week for the whole cohort and did not diminish with increased duration of therapy. Granulocytopenia and thrombocytopenia were well controlled, with the average duration of platelet and neutropenic nadirs being less than 1 day for all cycles. There was no evidence of cumulative toxicity for granulocytes nor platelets, for up to eight cycles of therapy. We conclude that taxol, when given with G-CSF support, can be safely administered in a dose-intense fashion for multiple cycles of therapy, without cumulative bone marrow toxicity.

Adenocarcinoma↗
PubMed1993

High-dose carboplatin and recombinant granulocyte-macrophage colony-stimulating factor in advanced-stage recurrent ovarian cancer.

PURPOSE: We investigated whether carboplatin myelosuppression could be favorably modulated by the administration of recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF) in patients with advanced-stage ovarian cancer. PATIENTS AND METHODS: Thirty-four patients with advanced-stage recurrent ovarian cancer were treated with high-dose carboplatin (800 mg/m2 per 35-day cycle) and rGM-CSF. rGM-CSF was administered as a daily subcutaneous injection starting 72 hours after the carboplatin dose and continuing until 7 days beyond the WBC nadir. rGM-CSF was administered in a phase I fashion. Seven patients were treated at an rGM-CSF dose of 3 micrograms/kg, 11 at 5 micrograms/kg, 10 at 10 micrograms/kg, and six at 20 micrograms/kg. RESULTS: rGM-CSF-related toxicities that were not dose-related included nonneutropenic fever, rib pain, acute hypersensitivity reaction, and pericarditis. At the rGM-CSF dose of 20 micrograms/kg, debilitating malaise was seen in four of six patients and this was the dose-limiting toxicity. Patient tolerance of the 3-micrograms/kg and 5-micrograms/kg doses was good, but tolerance was limited for the 10-micrograms/kg dose. Febrile neutropenia was seen in four of seven patients at 3 micrograms/kg, two of 11 at 5 micrograms/kg, two of 10 at 10 micrograms/kg, and one of six at 20 micrograms/kg. Cumulative carboplatin myelotoxicity was blunted only in respect to WBC count, and not for platelets or RBCs. Gastrointestinal bleeding was seen in seven patients. The administered dose-intensity of carboplatin averaged 134 mg/m2/wk for the cohort, or 670 mg/m2 per 35-day cycle. There were two clinical complete responses and eleven partial responses, for a response rate of 38%. CONCLUSION: rGM-CSF appears to be effective and tolerable at 5 micrograms/kg/d administered subcutaneously, if given with carboplatin doses up to approximately 600 mg/m2 over 35 days. The use of rGM-CSF with high-dose carboplatin is associated with a substantial response rate in poor-prognosis ovarian cancer patients.

Adult↗
PubMed1992

Phase I study of taxol and granulocyte colony-stimulating factor in patients with refractory ovarian cancer.

PURPOSE: To increase the taxol dose beyond the current standard dose intensity of 175 mg/m2 per 21 days in patients with refractory ovarian cancer. PATIENTS AND METHODS: Fifteen patients who had platinum-refractory or recurrent advanced-stage ovarian cancer were treated with taxol in a phase I trial and were given granulocyte-colony stimulating factor (G-CSF). Taxol was administered at doses of 170, 200, 250, and 300 mg/m2 every 3 weeks. G-CSF was given as a daily subcutaneous injection that started 24 hours after the completion of the taxol infusion. RESULTS: Four patients required either taxol dose reduction or delay. The dose-limiting toxicity (DLT) was peripheral neuropathy, and it occurred at 300 mg/m2. This toxicity was manifested clinically as a stocking-and-glove sensory disturbance that primarily affected proprioception, and was associated with objective changes on nerve conduction studies in affected individuals. Mucositis was rarely observed. Substantial myelosuppression was observed, but was not dose-limiting. Five of 14 assessable patients experienced an objective response to therapy, with another five individuals who experienced a 30% to 45% reduction in tumor mass. CONCLUSION: Taxol can be safely administered in doses up to 250 mg/m2 with G-CSF support, which may make it possible to study taxol dose intensification.

Adult↗
PubMed1988

Antiarthritic synergism of combined oral and parenteral chrysotherapy. I. Studies in adjuvant-induced arthritis in rats.

In comparative clinical studies of auranofin (AF, oral gold) and parenteral gold in the treatment of rheumatoid arthritis, no difference in efficacy was detected. Since the pharmacologic profiles of these compounds are different, we studied their combined effect on adjuvant arthritis (AA). The effect of AF alone and combined with gold sodium thiomalate (GTM) or gold sodium thiosulfate (GTS) on the excretion of urinary hydroxyproline (UHP) and urinary calcium (UCa), and the articular index of arthritic rats was followed during five weeks of treatment. The excretion of UHP and UCa was significantly inhibited (P less than 0.005) in rats treated with AF combined with GTM or GTS as compared with animals treated with the individual gold compounds. However, the articular index only decreased significantly (P less than 0.02) in the group of rats treated with AF + GTS. The present studies open the possibility that combined treatment with oral and injectable gold provide a new approach for chrysotherapy with an increased antiarthritic potency.

Administration, Oral↗
PubMed1988

Antiarthritic synergism of combined oral and parenteral chrysotherapy. II. Increased inhibition of activated leukocyte oxygen burst by combined gold action.

We have observed an antiarthritic effect of combined chrysotherapy in adjuvant arthritis. Since superoxide radicals (O2-) are potent mediators of rheumatoid inflammation, we studied the combined effect of auranofin (AF) and injectable golds on luminol-dependent chemiluminescence (LDCL) and O2- generation by cytochrome-c reduction of activated leukocytes by different receptor-mediated stimuli: phorbol myristic acetate, 10(-6) M; f-Met-Leu-Phe, 10(-6) M; and poly-L-histidine, 10(-5) M. AF, 0.6 and 0.9 micrograms Au/ml, inhibited 34 and 58% of O2- generation, respectively; the addition to AF of 0.3 micrograms Au/ml of gold thiosulfate (GTS) increased this inhibition to 84 and 97% of the oxygen burst. Similar synergistic potentiation inhibition was obtained by LDCL. When the inhibition of O2- generation by the combined action of AF and GTS was compared with AF + gold sodium thiomalate (GTM), only GTS showed an activation on AF's inhibition of the oxygen burst of human leukocytes. The ligand thiosulfate in equimolar concentrations to GTS had a statistically significant (P less than 0.01) inhibitory effect on AF's blockade of O2- generation during the first 5 min of the interaction with the PMNs; thiomalate had no effect. Sequential pretreatment of PMNs with AF and GTS on O2- generation revealed that for synergism of combined gold action to take place, the cell membrane had to be subjected first to the action of oral gold or to the simultaneous combined action of oral and parenteral gold.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1982

Extracellular matrix promotes mammary epithelial growth and differentiation in vitro.

The study of growth and differentiation of mammary epithelium has been hampered by the difficulty of maintaining these functions in vitro. We describe a system for the primary culture of rat mammary epithelium on an acellular matrix derived from whole rat mammary glands that maintains growth and differentiation for months. Cultures plated on this complex substratum produce 50 times the alpha-lactalbumin of those on tissue culture dishes and 5 times the alpha-lactalbumin of those on floating collagen gels as determined by radioimmunoassay. Unlike cultures grown on floating collagen gels, which rapidly lose the ability to secrete the milk sugar lactose, mammary cells on this matrix retain this ability for over 30 days in culture. The organ specificity of this mammary extracellular material is shown by the failure of extracellular matrix prepared from rat liver to support mammary differentiation. Within a given culture dish, cells on the surface of mammary extracellular matrix are more differentiated than those on the adjacent plastic. This is demonstrated by their increased alpha-lactalbumin content as shown by indirect immunofluorescence, and by their increased ability to bind fluorescein-conjugated peanut lectin. Cells on the surface of the matrix continue to synthesize DNA as determined by [3H]thymidine incorporation and autoradiography. Even when mammary epithelial cells are plated at low density, cell division continues until the matrix is covered with a confluent layer. We propose that the limited growth, differentiation, and survival of mammary cells in previously described in vitro systems may have been due to substrate that were inadequate to support these functions.

Animals↗