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Biomedical subjects

P A Bunn

Publications and source records attributed to P A Bunn.

At least 19 recordsLinked to original sources
PubMed1992

Elevated DT-diaphorase activity and messenger RNA content in human non-small cell lung carcinoma: relationship to the response of lung tumor xenografts to mitomycin Cł.

The enzyme DT-diaphorase (DTD; NAD(P)H:quinone oxidoreductase, EC 1.6.99.2), is an obligate two electron reductase which catalyzes reduction of a broad range of substrates, including quinones. We report here variations in DTD concentrations among different classes of lung tumors known also to vary in their responsiveness to cytotoxic agents. Small cell lung carcinomas (SCLCs) and cell lines derived from them have the low DTD activities and mRNA content characteristic of normal human lung, whereas non-small cell lung carcinomas (NSCLCs) have greatly elevated levels. DTD activity was increased up to 80-fold in NSCLC tumors relative to normal lung and 20-35-fold in NSCLC relative to SCLC cell lines. Increased DTD activity appeared to be a function of the NSCLC phenotype rather than a result of derivation from a cell type rich in DTD, since all histological classes of NSCLC showed this phenotype. In addition, where transfection of SCLC cell lines with the v-Ha-ras protooncogene caused a transition to a NSCLC phenotype, DTD activity was also elevated. Neuroendocrine-positive cells (SCLC, carcinoids, and a few NSCLC lines) typically had far lower DTD activities than did cell lines which lacked neuroendocrine markers (most NSCLC cells and mesotheliomas). High DTD activity may be exploited in the design of drugs which undergo bioreductive activation by this enzyme. Consistent with this, xenografts derived from NSCLC cell lines with high DTD that were grown in athymic nude mice were more susceptible to the antitumor quinone, mitomycin C, than were xenografts derived from SCLC cells containing low DTD. These data provide a mechanistic basis for the rational design of more effective bioreductive antitumor agents for use against NSCLC.

Animals↗
PubMed1992

Secondary screening system for preclinical testing of human lung cancer therapies.

The National Cancer Institute has instituted a primary screening system for testing new agents against cultured cancer cell lines. The purpose of this study was to determine the feasibility of using a nude rat orthotopic (organ-specific) human lung cancer model system as an in vivo secondary screen for general evaluation of new anticancer agents and therapies active against lung cancer. To make this determination, we tested whether this system allows measurement of uptake and tumoricidal activity of anticancer therapies. Tumor-bearing lungs from 53 Rowett nude rats with orthotopically implanted human large-cell undifferentiated lung carcinoma (NCI-H460) were perfused ex vivo for 1 hour with or without each of two anticancer modalities. Lungs were perfused with blood-free perfusate alone (untreated control), perfusate with 100 micrograms/mL doxorubicin (treated positive control), or perfusate with lymphokine-activated killer cells plus human recombinant interleukin-2 (LAK/rIL-2). Weight gain during perfusion was the criterion used to quantitate lung injury. Treatment efficacy was measured by clonogenic assay after enzymatic disaggregation of the perfused tumors. Doxorubicin levels in the tumor and in the uninvolved lung were measured by high-performance liquid chromatography. Both treatment groups showed only slight increases in lung weight compared with that in the untreated control group, suggesting good lung tolerance of the procedure. Lung and tumor levels of doxorubicin were 320 +/- 21 ng/mg of tissue and 32 +/- 5 ng/mg of tissue (means +/- SE), respectively. Clonogenic assay demonstrated a fivefold to 10-fold reduction in the surviving fraction of tumor cells with doxorubicin but no change with LAK/rIL-2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Neuropeptide signal transduction in lung cancer: clinical implications of bradykinin sensitivity and overall heterogeneity.

To define the role of neuropeptides in lung cancer biology, we evaluated the effect of seven peptide classes on signal transduction and growth in human lung and breast cancer cell lines. Flow cytometric methods were used to quantitate the calcium response in individual cells produced by these peptides alone or in combination. The effects on growth were assessed by [3H]thymidine, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, and soft agarose colony assays. All lung cancer cells demonstrated calcium responses to one or more peptides with classic small cell lines displaying the greatest responsiveness, followed by variant small cell lines and non-small cell lines. Breast cancer cell lines demonstrated little or no response. There was great variability in the magnitude of calcium response and pattern of response between lung cancer cell lines to individual neuropeptides. Bradykinin was the most potent peptide and produced responses in the highest fraction of lung cancer cell lines. Combinations of peptides produced greater intracellular calcium release than the single peptides, although in less than a quantitatively additive manner. Each peptide produced a refractory period which was peptide class specific. The growth stimulating effects of these neuropeptides were absent or small in magnitude and did not correlate with calcium signal transduction. These results imply that lung cancer cells display a wide sensitivity to neuropeptides but in a very heterogeneous manner. Knowledge of this heterogeneity should be incorporated into the design of antitumor strategies based on this autocrine pathway.

Bombesin↗
PubMed1992

Clinical experiences with carboplatin (paraplatin) in lung cancer.

Lung cancer is the most lethal cancer in the United States, with 143,000 deaths predicted for 1991. The cure rate is extremely low (approximately 13%), in part because the propensity for early spread precludes surgical cure in most patients. Thus, chemotherapy or other systemic therapies are the only way to improve the dismal results. Cisplatin is an active agent in small cell lung cancer (SCLC) and perhaps the most active agent in nonsmall cell lung cancer (NSCLC). The toxicities and inconvenience of cisplatin make it less than ideal for lung cancer therapy. Carboplatin was developed to provide a less toxic, more convenient alternative to cisplatin. The data presented in this review suggest that carboplatin may be substituted for cisplatin in the treatment of extensive-stage SCLC. In limited-stage SCLC, there are insufficient data to determine whether it should replace cisplatin when used simultaneously with chest irradiation and etoposide. It may be substituted for cisplatin in cycles not using irradiation. In NSCLC, carboplatin may be used alone or with etoposide for the palliative management of metastatic disease. Its role in earlier stages of NSCLC needs investigation.

Carboplatin↗
PubMed1992

Effects of neuropeptides on human lung and breast cancer cells.

We evaluated the effect of seven classes of neuropeptides [bradykinin, cholecystokinin 26-33 (CCK), neurotensin, arginine-8 vasopressin (AVP), tyr-4 bombesin (BN), somatostatin, and motilin] on 18 human lung cancer and four human breast cancer cell lines to determine the pattern of responses. Flow cytometric analysis of Indo-1 AM-loaded cells was used to quantitate the intracellular calcium response of individual cells produced by these peptides alone or in simultaneous or sequential combinations. All 18 lung cancer cell lines responded to one or more peptide classes with classic small cell lines displaying the greatest responsiveness, followed by variant small-cell lines and non-small-cell lung cancer cell lines. Breast cancer cell lines demonstrated little or no response to any peptide. There was great variability in the magnitude of response and pattern of response in individual cell lines and between cell lines. Bradykinin was the most potent peptide and produced responses in the largest number of lung cancer cell lines. Simultaneous administration of active peptides produced greater intracellular calcium release than single peptides, though in a less than additive manner. Response to each peptide was followed by a refractory period lasting several hours or more. The refractoriness was peptide-specific, implying that each peptide has a distinct pathway, at least at the receptor level. Bradykinin antagonists could abrogate the calcium response to bradykinin but not to other peptides. Similarly, specific peptide antagonists for CCK, BN, and AVP blocked the response for only their specific agonist.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Neoplasms↗
PubMed1979

Thymosin fraction V and intensive combination chemotherapy. Prolonging the survival of patients with small-cell lung cancer.

Patients with small-cell bronchogenic carcinoma who received intensive remission-induction chemotherapy randomly received either thymosin fraction V, 60 mg/sq m or 20 mg/sq m twice weekly, or no thymosin treatment during the initial six weeks of chemotherapy. Chemotherapy was then continued for two years. Thymosin administration did not increase the complete response rate. Patients receiving thymosin, 60 mg/sq m, had significantly prolonged survival times relative to the other treatment groups. This benefit was due to prolonged relapse-free survival in complete responders to treatment. The mechanism by which thymosin increased survival duration is unclear but may relate to restoration of immune deficits due to disease or treatment.

Antineoplastic Agents↗
PubMed1979

Response to thoracic radiotherapy in patients with small cell carcinoma of the lung after failure of combination chemotherapy.

Chest radiotherapy was given to 23 patients with small cell carcinoma of the lung after development of progressive intrathoracic tumor on chemotherapeutic regimens. Treatment schedules were variable, with a median dose of 3,200 rad (32 Gy) in 10 fractions. Objective tumor regression within the radiation portal was observed in 12 patients (52%). Only 3/12 responders did not develop clinically detectable local tumor recurrence before death. Actuarial median time to local tumor progression was 2.5 months in responding and 3.5 months in nonresponding patients. Relapse of intrathoracic small cell carcinoma despite combination chemotherapy was not effectively treated by chest irradiation in the doses utilized. If sustained local palliation is required in this population, higher doses of radiation should be considered.

Carcinoma, Small Cell↗
PubMed1979

Cyclic alternating combination chemotherapy for small cell bronchogenic carcinoma.

Sixty-one protocol-eligible patients with small cell bronchogenic carcinoma received cyclic alternating combination chemotherapy with two or three non-cross-resistant drug combinations. No chest or prophylactic brain radiation therapy was used. Twenty-eight months after starting treatment, disease-free survival was 23% for patients achieving a complete response (CR) and 13% overall. Initial treatment consisted of high-dose cyclophosphamide, methotrexate, and CCNU (CMC) for 6 weeks. Patients then received vincristine, adriamycin, and procarbazine (VAP) for 6 weeks. The addition of VAP increased the CR rate from 42% to 74% in limited-disease patients and from 24% to 36% in extensive-disease patients. Half of the patients were randomized to a third combination of VO-16-213 and ifosfamide. These patients were cycled at 6-week intervals through the three drug regimens while the remaining patients were cycled between CMC and VAP. The addition of VP-16-213 and ifosfamide did not increase the CR rate or prolong survival. Only complete responders survived beyond 24 months. Sequential use of non-cross-resistant drug combinations represents one method for increasing the CR rate.

Antineoplastic Agents↗
PubMed1979

In vitro growth of cutaneous T-cell lymphomas.

It is relatively easy to propagate EB virus-transformed normal and malignant B lymphocytes in vitro. Normal T lymphocytes divide for short periods of time after exposure to many mitogens. Exposure of normal T lymphocytes to lymphocyte-conditioned medium (LCM) permits them to divide for longer periods of time, but permanent cell lines cannot be established. Intial attempts to grow malignant T cells from patients with cutaneous T-cell lymphomas (CTCL) in unsupplemented growth medium resulted in the establishment of four EB virus-transformed B-lymphoblastoid lines. The responses of CTCL cells to mitogens and LCM varied from unresponsive to near normal. Subsequent attempts to grow CTCL cells in medium supplemented with mitogens or LCM resulted in the establishment of two cell lines lacking B-cell markers or EB virus. The cells of both lines initially had the ability to form E rosettes, although one of the lines has lost this ability with passage. The two lines can be distinguished from normal T cells by having some or all of the following properties: long-term proliferation, tumorigenecity in nude mice, gradual loss of dependence on mitogen or LCM, and convoluted nuclear morphology.

Animals↗
PubMed1979

Blood and lymph node T lymphocytes in cutaneous T cell lymphoma: evaluation by light microscopy.

Cytology of peripheral blood and lymph node lymphocytes from a group of unselected patients with cutaneous T cell lymphoma (CTCL) was studied by light microscopy. Twenty of 45 patients had circulating lymphocytes with convoluted nuclei recognized in routine Wright-Giemsa-stained peripheral blood smears. Cytocentrifuge preparations of E-rosetted lymphocytes showed that greater than 10% of the T cells had convoluted nuclei in each of 16 patients with positive blood smears and in six of 17 whose blood smears were negative or inconclusive. Peripheral blood involvement with greater than 10% convoluted T cells was most frequent in patients with erythroderma (100%) including those with normal of decreased lymphocyte counts, and was not uncommon in patients with mycosis fungoides in the plaque or tumor phase (42%). The light-microscopic morphology of the abnormal cells found in the patients with the plaque or tumor phase of mycosis fungoides was not distinguishable from that of the erythrodermic patients. Increased percentages (less than 15%) of T cells having convoluted nuclei were also found in the lymph node cell suspensions from CTCL patients with adenopathy (18 of 25 patients). These results suggest that a high frequency of extracutaneous involvement occurs in patient with CTCL, the clinical significance of which remains to be determined.

Humans↗