Search PubMed⌕ Search

Biomedical subjects

D N Carney

Publications and source records attributed to D N Carney.

At least 127 records · Page 7Linked to original sources
PubMed1985

Neurotensin is produced by and secreted from classic small cell lung cancer cells.

The presence of neurotensin in various human tumor cell lines was investigated by radioimmunoassay. High concentrations (0.06-5.1 pmol/mg protein) were detected in 50% of the classic but not variant small cell lung cancer or other human tumor cell lines examined. Biochemical studies indicated that the main peak of immunoreactivity coeluted with synthetic neurotensin using gel filtration and high pressure liquid chromatography techniques. Also, the rate of neurotensin secretion increased approximately 2-fold when theophylline was added which elevated intracellular levels of cAMP 4-fold. Because neurotensin is present in and secreted from many classic small cell lung cancer cells, it may function as a regulatory peptide in this disease.

Adenocarcinoma↗
PubMed1985

The role of radiation therapy in the treatment of small cell lung cancer.

Patients with small cell lung cancer (SCLC) are candidates for aggressive therapy because of their potential for long-term survival, especially patients with limited-stage disease. Although no treatment protocol can be considered "standard", the best results in limited-stage SCLC appear to be produced by a combination of chemotherapy and thoracic irradiation. Ongoing protocols testing the efficacy of thoracic irradiation should be able to settle question of the optimal treatment approach in limited-stage SCLC over the next 1 to 2 years. Careful attention to volume treated and the use of shrinking fields produce the best results with the minimum of toxicity. Treatment of extensive-stage SCLC has not been substantially improved to date with the addition of local or systemic irradiation. Prophylactic cranial irradiation reduces the incidence of CNS failure in SCLC and should be given, at a minimum, to patients achieving complete response status. Whether patients with partial response should also receive prophylactic cranial irradiation remains controversial. Finally, half-body radiation in SCLC is an experimental research technique that has shown some promise but remains quite toxic when combined with systemic chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1985

Suppression of murine immunologic functions by fresh and cultured human tumor extracts.

The role of human tumor-derived immunoregulatory factors (IRF) in the suppression of murine in vitro cell-mediated immune systems was investigated. IRF was extracted from a fresh human colon carcinoma and a liposarcoma using 3 M KCl. These extracts have previously been shown to suppress in vitro human immune responses. Both IRF extracts inhibited PHA-stimulated murine splenocyte [3H]Tdr uptake in a dose-dependent manner while extracts of normal tissue were not inhibitory. To further investigate in vitro immunosuppression a (C57BL/6 X A/J) F1 anti-B10. BR mixed lymphocyte reaction (MLR) was developed. Optimal [3H]Tdr incorporation was on Day 4 with 1 X 10(5) responders and 2 X 10(5) irradiated stimulators. Addition of IRF caused a 56% inhibition of this response but did not alter the kinetics of the MLR response. Induction of cell-mediated cytotoxicity (C57BL/6 X A/J F1 vs B10.D2) was significantly inhibited by addition of IRF during in vitro sensitization. Release of 51Cr from P-815 targets was decreased to spontaneous release levels at an effector:target (E:T) ratio of 20:1 when IRF was present during sensitization. At this E:T ratio, cells sensitized in the presence of a normal muscle 3 M KCl extract or medium caused 71 and 60% 51Cr release, respectively. IRF activity could also reproducibly be extracted from two small cell lung carcinoma tissue culture lines grown under a variety of culture conditions or passaged in nu/nu mice. The biochemical characteristics of the factor inhibiting human and murine lymphoid cell proliferation were identical. Thus, this system provides a convenient model for assessing the activity of human tumor-derived immunoregulatory factors.

Animals↗
PubMed1985

Differential expression of intermediate filament proteins distinguishes classic from variant small-cell lung cancer cell lines.

The expression of intermediate filament proteins in classic and variant-type small-cell lung carcinoma (SCLC) cell lines was studied using immunocytochemical techniques, two-dimensional gel electrophoresis and immunoblotting assays. Classic SCLC cell lines contain cytokeratin proteins but no neurofilaments. In contrast, variant cell lines do not contain detectable amounts of cytokeratins but partly express neurofilaments and vimentin. These results explain apparent discrepancies on the intermediate filament content of SCLC described in the recent literature. The application of antibodies to fresh biopsy specimens of SCLC may in the future allow the identification of the variant type of cells in clinical SCLC specimens and may have a major impact on therapeutic strategy and prognosis in these patients.

Carcinoma, Small Cell↗
PubMed1985

Relationships between the cytotoxicity of tiazofurin and its metabolism by cultured human lung cancer cells.

The antitumor activity of the antineoplastic agent, tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide), has previously been shown to require intracellular anabolism of the drug to a nicotinamide adenine dinucleotide (NAD) analog (2-beta-D-ribofuranosylthiazole-4-carboxamide adenine dinucleotide or "tiazofurin adenine dinucleotide"), which then acts as a potent inhibitor of the target enzyme inosine monophosphate (IMP) dehydrogenase. Inhibition of the latter enzyme in turn brings about a profound depletion of intracellular guanosine nucleotides essential for tumor cell growth and replication. In the present study, the cytotoxicity and metabolism of tiazofurin have been examined in six human lung cancer cell lines. At the pharmacologically attainable drug concentration of 100 microM, colony survival was less than 1.5% in three cell lines ("sensitive"), while survival in the remaining three was greater than 50% ("resistant"). The metabolism of tritiated tiazofurin was examined at concentrations ranging from 0.5 to 100 microM following both brief (6 h) and protracted (14 d) exposures. The sensitive lines accumulated concentrations of tiazofurin adenine dinucleotide that were approximately 10 times those achieved by the resistant lines at both time points. We also observed tendencies for the sensitive cell lines to exhibit: (a) higher specific activities of NAD pyrophosphorylase, the enzyme required for the synthesis of tiazofurin adenine dinucleotide, (b) significantly lower levels of a phosphodiesterase which degrades the latter dinucleotide, (c) greater inhibition of the target enzyme IMP dehydrogenase, and (d) greater depressions of guanosine nucleotide pools after drug treatment. By contrast, the basal levels of IMP dehydrogenase and purine nucleotides in these six lines did not correlate in any obvious way with their responsiveness or resistance. The accumulation and monophosphorylation of parent drug were also not prognostic variables. These studies thus suggest that the extent of accumulation of tiazofurin adenine dinucleotide, as regulated by its synthetic and degradative enzyme activities, is the single most predictive determinant of the responsiveness of cultured human lung tumor cells to tiazofurin.

Adenine Nucleotides↗
PubMed1985

Determinants of the sensitivity of human small-cell lung cancer cell lines to methotrexate.

We have characterized the determinants of methotrexate (MTX) responsiveness in eight patient-derived cell lines of small-cell lung cancer (SCLC). Clonogenic survival was correlated with factors known to affect sensitivity to drug. NCI-H209 and NCI-H128 were most drug sensitive, with drug concentrations required to inhibit clonogenic survival by 50% with less than 0.1 microM MTX. Six cell lines (NCI-H187, NCI-H345, NCI-H60, NCI-H524, NCI-H146, and NCI-N417D) were relatively drug resistant. In all cell lines studied, higher molecular weight MTX-polyglutamates (MTX-PGs) with 3-5 glutamyl moieties (MTX-Glu3 through MTX-Glu5) were selectively retained. Relative resistance to low (1.0 microM) drug concentrations appeared to be largely due to decreased intracellular metabolism of MTX. Five of the six resistant lines were able to synthesize polyglutamates at higher (10 microM) drug concentrations, although one resistant cell line (NCI-N417D) did not synthesize higher molecular weight MTX-PGs, even after exposure to 10 microM drug. Two cell lines with resistance to 10 microM MTX (NCI-H146 and NCI-H524) synthesized and retained higher molecular weight MTX-PGs in excess of binding capacity after exposure to 10 microM drug. However, the specific activity of thymidylate synthase in these cell lines was low. MTX sensitivity in patient-derived cell lines of SCLC requires the ability of cells to accumulate and retain intracellular drug in the form of polyglutamate metabolites in excess of dihydrofolate reductase, as well as a high basal level of consumption of reduced folates in the synthesis of thymidylate.

Biological Transport, Active↗
PubMed1985

Growth of human lung tumor in the brain of the nude rat as a model to evaluate antitumor agent delivery across the blood-brain barrier.

We have developed a brain tumor model in the nude rat utilizing NCI-N417D human small cell carcinoma of the lung grown both intracerebrally and s.c. The median latency period from the time of intracerebral tumor inoculation to the onset of neurological symptoms is 13 days with an intracerebral tumor take rate of 91% (29 of 32). The median survival is 13 days, and all animals were dead by Day 26. The tumor is discrete, well circumscribed, with occasional leptomeningeal spread and with minimal evidence of surrounding cerebral edema. Intracerebrally, this tumor is usually impermeable to Evan's blue:albumin (Mr 68,500) but not fluorescein (Mr 376). Although variable, the intracerebral tumor is less permeable to methotrexate than is the same tumor grown s.c. in the same animal (P less than 0.005). The intraarterial and i.v. routes of methotrexate administration in the presence and absence of blood-brain barrier opening were evaluated. Drug delivery to the intracerebral tumor and ipsilateral brain was significantly (P less than 0.025) greater when the methotrexate was given intraarterially and was significantly (P less than 0.0025) increased after osmotic blood-brain barrier opening. After barrier opening, methotrexate concentration was enhanced 3- to 4-fold in tumor and 10- to 20-fold in brain around tumor. Thus, the nude rat provides a model to investigate the biology and therapeutic responsiveness of human small cell carcinoma of the lung grown intracerebrally where it develops a blood-tumor barrier similar to that seen in humans. This model further provides the unique opportunity to investigate the role of osmotic blood-brain barrier opening in the treatment of a tumor which is sensitive to chemotherapeutic agents and for which tumor-specific monoclonal antibodies are available.

Animals↗
PubMed1985

Establishment and identification of small cell lung cancer cell lines having classic and variant features.

Using a chemically defined medium containing hydrocortisone, insulin, transferrin, 17 beta-estradiol and selenium, with or without serum supplementation (2.5% v/v), continuous cell lines can be established from 72% of all fresh biopsy specimens of small cell lung cancer (SCLC) containing tumor cells. No differences were observed in the rate of establishing cell lines from newly diagnosed untreated patients, or from patients who have relapsed from prior therapy, or from a variety of different organ sites. Biochemical characterization of 50 SCLC cell lines for the expression of L-dopa decarboxylase; bombesin-like immunoreactivity; neuron-specific enolase, and the brain isozyme of creatine kinase, revealed that SCLC cell lines can be subdivided into two distinct classes: classic SCLC cell lines (35 lines), which express elevated levels of all four biomarkers; and variant SCLC cell lines (15 lines) which have undetectable levels of L-dopa-decarboxylase and bombesin-like immunoreactivity, but continue to express neuron-specific enolase and the brain isozyme of creatine kinase. The presence of the latter two markers distinguishes variant lines fron non-SCLC cell lines. In addition, four distinct classes were identified morphologically. The biomedical differences among established SCLC cell lines may account for the differences in response rates to cytotoxic therapy observed in newly diagnosed SCLC patients. A prospective study of biomarker characterization of SCLC tumors will determine if clinical differences exist between classic and variant SCLC tumors.

Animals↗
PubMed1985

Characterization of variant subclasses of cell lines derived from small cell lung cancer having distinctive biochemical, morphological, and growth properties.

We have described the establishment and biochemical characterization of 50 small cell lung carcinoma (SCLC) cell lines. Further analysis of these data, combined with studies of morphology and growth characteristics, indicates that 35 (70%) of the lines retained typical morphology (SCLC, intermediate subtype), growth characteristics (growth as tightly packed floating cellular aggregates, long doubling times and low colony-forming efficiencies), and biochemical profile (presence of L-dopa decarboxylase, bombesin-like immunoreactivity, neuron-specific enolase, and high concentrations of brain isoenzyme of creatine kinase). They are referred to as classic SCLC lines. The remaining 15 (30%) lines had discordant expression of the biochemical markers; they retained high concentrations of brain isozyme of creatine kinase, but had significantly lower concentrations of neuron-specific enolase and lacked L-dopa decarboxylase and bombesin-like immunoreactivity. These cell lines are called variants. SCLC variant lines could further be divided into (a) biochemical variant lines having variant biochemical profile but retaining typical SCLC morphology and growth characteristics; and (b) morphological variant (SCLC-MV) lines having variant biochemical profile, altered morphology (features of large cell undifferentiated carcinoma) and altered growth characteristics (growth as loosely attached floating aggregates, relatively short doubling times and cloning efficiencies). Fifty-five clones derived from the three SCLC subclasses retained their parental phenotypes. In SCLC-MV lines there was a near constant relationship between variant morphology, altered growth characteristics and amplification of the c-myc oncogene; classic SCLC and biochemical variant SCLC lines were not amplified. Variant morphologies frequently are present in SCLC tumors at autopsy, and most SCLC-MV lines reflect changes that had occurred in the tumors from which they were derived. Because SCLC-MV tumors behave more virulently in the patient and are radioresistant in vitro, these findings are of considerable biological and clinical interest.

Bombesin↗
PubMed1985

Biological heterogeneity of small cell lung cancer.

Over the past 20 years considerable advances have been made in the characterization of the biologic properties of small cell lung cancer. The recognition that this histologic type of lung cancer, in contrast to the other major types of lung cancer, is highly sensitive to both chemotherapy and radiation therapy lead to significant improvements in the overall survival of patients with this disease. However, in spite of the initial major advances in therapy, overall results and survival have remained unchanged over the past 5 years. The majority of patients, although they will demonstrate an initial response to cytotoxic therapy, will ultimately die of their disease due to the development of drug resistance. Whether this development of drug resistance within a tumor cell represents the emergence of resistant clones of cells present at diagnosis, or a change within the cells exposed to cytotoxic therapy that renders them resistant to further therapy remains to be determined. The development of laboratory techniques that facilitate the culture and establishment of SCLC cell lines has greatly improved our understanding of the biology of SCLC, in addition to providing useful models for studies of mechanisms of drug resistance and metabolism. The ease of establishment of SCLC cell lines in defined medium suggests that these cells secrete "autocrine growth factors" essential for their growth in vitro. The characterization of these factors may provide an alternative means for treating this tumor in vivo. Moreover, by developing specific culture media for other types of lung cancer, similar advances in our knowledge of these tumors will occur. Although the growth of SCLC cells in a clonogenic assay may be of value in chemotherapy selection, the established cell lines provide a model for studying mechanisms of drug and radiation sensitivity; and drug metabolism. The recognition that SCLC cell lines have elevated levels of L-dopa decarboxylase has lead to the development of specific agents that may alter the growth of these cells through inhibition of polyamine synthesis. Such specifically designed therapy may become important in the future therapy of these patients. The establishment of cell lines has clearly indicated the considerable heterogeneity that exists in SCLC.(ABSTRACT TRUNCATED AT 400 WORDS)

Antigens, Neoplasm↗
PubMed1985

In vitro assays of chemotherapeutic sensitivity.

The concept of designing an in vitro assay to predict in vivo antineoplastic drug activity that would provide the medical oncologist with the necessary data to define beneficial drug regimens is appropriate; however, the optimal assay has been elusive over the last 3 decades. It is hoped that information gained from attempts to design such an assay has provided further refinements that will bring the goal in reach. The initial studies of drug-induced cell cytotoxicity employing changes in cell metabolism or the cell's ability to exclude supravital dye or reduction in the incorporation of radiolabeled precursors into DNA, RNA, or proteins provided the starting point for developing such an assay. Although initial enthusiasm existed with each of these assays, it soon became apparent that their predictive value was not sufficiently specific to warrant broad application. Modification of the dye exclusion assay or the combination of the clonogenic assay with radio precursor incorporation may provide better predictability. Confirmation of these assays awaits completion of randomized clinical trials. More recently, led by the appreciation of a subset of self-renewing cells--that is, "stem cells" present in the bone marrow--Salmon and colleagues reported on the pertinent applications of the clonogenic assay in predicting in vivo patient responses to chemotherapy. Since this report, considerable advances in development, improvement, and application of the clonogenic assay have occurred. This assay has been applied to preclinical screening of new antineoplastic agents, cytogenetic analysis of human tumor specimens, and the identification of growth factors and hormones for different tumor types. Despite these major advances in applying and solving technical problems associated with the assay, major problems continue to exist, the foremost being the overall poor growth of most tumor specimens in the assay such that in vitro chemosensitivity data can be obtained only in 30% to 40% of specimens. Indeed, because only this fraction grows, it is important to demonstrate that "growth itself" in the assay is not an independent prognostic factor. Further, pharmacologic considerations will have to be completed for each drug such that in vitro studies of drug exposure and drug/drug interaction will mimic the clinical situation. Constant critical analysis of this and other assays will no doubt lead to improvements, particularly their use as tools for biologic studies. Currently, insufficient data on prospective trials evaluating in vitro assays in predicting clinical responses are available.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Small cell lung cancer 1973-1983: early progress and recent obstacles.

The recognition that the vast majority of patients with small cell lung cancer have distant metastatic disease at the time of diagnosis led to the use of systemic chemotherapy and consequent major improvements in survival in the early to mid-1970's. In the past five years, however, the pace of therapeutic advances has slowed. Recently evaluated treatment strategies, including more intensive induction chemotherapy, "late intensive" therapy of responding patients, alternation of chemotherapeutic regimens, integration of chest irradiation with drug therapy, large field irradiation, and reappraisal of the value of surgical resection, are discussed in this review. Advances in understanding of the cell biology of small cell lung cancer which may eventually lead to new forms of treatment are summarized.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1984

Combination chemotherapy with doxorubicin and mitomycin C in non-small cell bronchogenic carcinoma. Severe pulmonary toxicity from q 3 weekly mitomycin C.

Forty-five patients with advanced, measurable, or evaluable non-small bronchogenic carcinoma (NSCBC) were treated with doxorubicin and mitomycin C combination chemotherapy. The first 27 patients received doxorubicin 50 mg/m2 I.V. every 3 weeks and mitomycin C 10 mg/m2 I.V. every 3 weeks. Because of severe cardiopulmonary toxicity in seven patients, with four otherwise unexplained deaths, the next 18 patients were treated with the mitomycin C dose reduced to 10 mg/m2 every 6 weeks. Overall, 11 patients (25%) responded, with one complete and 10 partial remissions. Eight responses (30%) were observed in the patients who received mitomycin C every 3 weeks and three responses (17%) were found in those given mitomycin C every 6 weeks (p less than 0.5), with no cardiopulmonary toxicity in the latter group. The median survival was 21 weeks for the entire group of patients, with the group receiving mitomycin C every 3 weeks living a median of 15.5 weeks and those given mitomycin C every 6 weeks surviving 35.5 weeks (p less than 0.025). We conclude that there is a higher tumor response rate but more cardiopulmonary toxicity and shorter survival among the group receiving mitomycin C every 3 weeks compared to those receiving mitomycin C every 6 weeks. Future studies should consider this toxicity of mitomycin C administered on an every-3-week schedule.

Adult↗