Neuropeptides as growth regulators

The classical role of neuropeptides as fast-acting neurohumoral signallers has recently been challenged by the discovery that many neuropeptides are also growth factors stimulating slow-acting mitogenesis. Their mechanisms of action have been studied in cell culture, and their cell-surface receptors have been characterized pharmacologically using agonists and antagonists. We describe the mitogenic effects of bombesin, vasopressin, bradykinin and vasoactive intestinal peptide in murine fibroblasts. We suggest that the receptors for bombesin, vasopressin and bradykinin have more than one binding site, permitting modulation of transmitted signals. As these neuropeptide receptors share the ability to mobilize intracellular Ca2+, their common domain may be essential to G-protein coupling.

Action potentials of cultured human oat cells: whole-cell measurements with the patch-clamp technique

Oat cells (of the small cell carcinoma of the lung) have been reported to generate calcium action potentials. The calcium channels have further been suggested to play a crucial role in the relation between oat cell carcinoma and the often associated myasthenic syndrome. We have examined cultured human oat cells (U-1690) under voltage-clamp conditions, using the patch-clamp technique. We found, contrary to previous reports, that the action potential was caused by sodium and potassium currents. No calcium current was detected under these conditions, which indicates that calcium channels, if present, are very rare. The findings restrict, but do not rule out, the hypothesis that calcium plays a key role in the carcinoma/myasthenic syndrome relation.

[Small cell lung cancer with Lambert-Eaton myasthenic syndrome]

Four of 69 cases of small cell lung cancer (SCLC) showed evidence of Lambert-Eaton myasthenic Syndrome (LEMS) were studied neurologically and neurophysiologically in four years. The LEMS appearance were preceded that of SCLC in 3 cases for two years at most. Repeated stimulation of ulnar nerve examination showed diminished amplitude of initial response (0.2-0.9 mv); Amplitude of the response at 3 c/s stimulation for 3 sec was diminished 20-63%. (control 3% decreases-13% increases) but that at 20 c/s stimulation for 10 sec increased 200-800% increases. (control: 20% decreases-56% increases). These findings were important for diagnosis of LEMS. The abnormalities of neurotransmission seems to be due to inadequate release of acetyl choline from nerve terminals at abnormal active zone of Ca++ channels.

The biology of lung cancer. A review

Advances in the understanding of the biology of lung cancer have progressed rapidly over the last decade. It is clear that considerable heterogeneity exists both in small-cell and non-small-cell lung cancer tumours with common properties being shared by both cell types. To further understand the prognostic and clinical significance of these biological properties it is clear that in future clinical trials of both tumour types these properties should be taken into consideration.

Site-specific growth of the prostate xenograft line UCRU-PR-2

A xenografted small-cell, undifferentiated prostate (SCUCP) cancer line, UCRU-Pr-2, was implanted at different sites within nude mice to examine the effect of local environmental factors on tumor growth and behavior. All tumors that grew were small-cell carcinomas. Fragments implanted within muscle and under the kidney capsule were locally invasive; however, tumors that grew subcutaneously or intraperitoneally showed no invasion. UCRU-Pr-2 did not grow in the spleen or the liver. No induced metastases were observed in the lung after intravenous injection. The sites of implantation did not allow the outgrowth of subpopulations as detected by the parameters used: light and electron microscopy, expression of tumor markers, levels of hormone production, and DNA flow cytometry. Electron microscopy, which showed both glandular and neuroendocrine differentiation within the same cell, does not support a dual-cell origin of SCUCP.

Identifying prognostic factors in binary outcome data: an application using liver function tests and age to predict liver metastases

A frequent issue confronting the medical scientist is the detection of important prognostic variables, or covariates, that affect the outcome variable. In this paper we propose specific guidelines for the analysis of binary outcome data based on recent developments in statistical methodology and on less formal graphical techniques. By incorporating these methods into the process of fitting the standard logistic regression model, one can assess covariate selection and model specification more thoroughly and obtain a more balanced view of a model's predictive capabilities. We apply the methods to the evaluation of non-invasive liver function tests and age to predict the presence of liver metastases in patients with small cell lung cancer.

Autonomic dysfunction in Lambert-Eaton myasthenic syndrome

Autonomic symptoms were observed in 6 patients with clinically and electrophysiologically documented Lambert-Eaton myasthenic syndrome (LEMS). Of the 6 patients, 2 were extensively investigated in the laboratory. In contrast to previous reports which recognized only cholinergic dysautonomia, abnormalities of sympathetic as well as parasympathetic function were evident. Of the 6 patients, 4 had small cell lung cancer (SCLC). In one male patient, chemotherapy for SCLC resulted in an early improvement of autonomic dysfunction and the electrophysiological defect, documenting simultaneous regression of dysautonomia and LEMS. In addition, the patients with SCLC and LEMS had a survival thus far of 3-13 years suggesting that a subgroup of SCLC patients have a better prognosis.

Bombesin-like peptides elevate cytosolic calcium in small cell lung cancer cells

The ability of bombesin-like peptides to elevate intracellular Ca2+ levels in small cell lung cancer cells was investigated using the fluorescent Ca2+ indicator Fura 2. Nanomolar concentrations of bombesin elevated cytosolic Ca2+ levels in the absence or presence of extracellular Ca2+. Potent bombesin receptor agonists, such as gastrin releasing peptide (GRP) or (GRP)14-27 elevated cytosolic Ca2+ levels whereas inactive compounds such as (D-Trp8)bombesin or (GRP)1-16 did not. Furthermore, the bombesin receptor antagonist (D-Arg1, D-Pro2, D-Trp7,9, Leu11) substance P (30 microM) had no effect on the Ca2+ levels by itself but antagonized the increase in Ca2+ caused by 10 nM or 100 nM bombesin. These data suggest that bombesin receptors may regulate the release of Ca2+ from intracellular organelles in small cell lung cancer cells.

Reversible squamous cell characteristics induced by vitamin A deficiency in a small cell lung cancer cell line

A cultured small cell lung cancer cell line (Lu-134-B-S) established from a xenotransplanted tumor in a nude mouse, which had originated from a primary focus of small cell lung cancer, showed morphological changes when the medium was changed from RPMI 1640 supplemented with 10% fetal calf serum to RPMI 1640 supplemented with 10% delipidized fetal calf serum. That is, it consisted of "classic" small cells in the former medium, but after eight passages in the latter medium many cells became squamous cells, possessing abundant eosinophilic cytoplasm and intercellular bridges. Immunohistochemically, they reacted to antikeratin and antiinvolucrin antibodies. Electron microscopically, well developed desmosomes and associated tonofibrils were noted, and electrophoretically, the amount of medium (Mr 57,000 and 59,000) and large-sized (Mr 67,000) keratins were found to increase with the change of the medium. These changes reversed to the original small cell morphology within 4 weeks after addition of vitamin A (retinoic acid) to the medium. These findings suggested that deficiency of vitamin A caused the change of the cell from small to squamous cell and vice versa.

Neurotoxicity of prophylactic cranial irradiation in patients with small cell carcinoma of the lung

This study is concerned with effects of prophylactic cranial irradiation on neurological and mental functioning of patients with small cell cancer of the lung. Results are reported of a pilot study in two parts. In a prospective clinical-neurological study, 14 patients with small cell cancer of the lung were evaluated with standard neurological and bedside mental status examinations, before and after irradiation. Their performance was compared with evaluation results of seven small cell cancer of the lung patients who received no irradiation. Dysfunctions were exclusively found in the irradiated patients, which are interpreted as a contributional effect of prophylactic cranial irradiation. Results are reported of further neuropsychological investigation in a sample of five prophylactic cranial irradiation patients. The presence of a rather specific pattern of neuropsychic deficits was confirmed. Areas of malfunctioning were described with some clinical and research implications.

Regional lung function in long-term survivors after chemotherapy for small cell lung cancer

In order to evaluate the regional lung function in patients with small cell lung cancer with long-term survival, we measured the regional lung function in 17 patients. We studied the patients with 81m-krypton ventilation scans and 99m-technetium perfusion scans, as well as measurements of static lung volumes (VC, RV, TLC), flow volume indices (FEV1, FVC, MEF50), and carbon monoxide diffusing capacity (DLCO). We found both the ventilation and the perfusion of the affected lung to be slightly but significantly lower (P less than 0.05), while no obvious ventilation or perfusion defects could be identified at the former tumor site. The static volumes of the lungs, the FVC and the FEV1 were within predicted normal values, while a significant decrease was seen in the PEF, MEF50, and DLCO. It is concluded that patients with small cell lung cancer who obtain complete remission with normalization of the chest X-ray and long-term survival after 18 months of intensive chemotherapy also have a nearly normal lung function.

Small cell lung cancer: a problem of tumor heterogeneity

Small cell undifferentiated carcinoma represents a subtype of lung cancer that possesses biologic and clinical characteristics that make it significantly distinct from other forms. A major impact on the natural history of this disease has been accomplished during the past 15 years, including the potential for cure by non-surgical treatment modalities. Further progress in the management of this disorder has been impaired by a number of factors that appear to be inherent to the biology of the tumor and its clinical features. Analysis of initial clinical trials and more detailed examination of this tumor in vitro have permitted the elucidation of many barriers to curative outcome presently being evaluated at the laboratory and clinical levels. These include clear biologic and morphologic heterogeneity; problems with chemotherapy responsiveness including drug resistance; the potential for combining chemotherapy and radiation modalities; the re-examination of the role of surgical intervention in selected patients; and the need to deal with central nervous system dissemination of tumor cells. Further advances in this disease will be dependent on the successful integration of laboratory and clinical disciplines.

Small cell carcinoma of the lung

Small cell lung cancer is a common, usually fatal neoplasm. Although palliative therapy is available for the majority of patients, only a very small minority enjoy long-term survival. Ironically, this neoplasm is nearly entirely preventable and a successful antismoking program is desperately needed. Our efforts to understand the basic biology of this tumor should continue, and, hopefully, will eventually translate into improvements in therapy. In addition to following the leads provided by basic research, a concerted clinical research effort needs to continue to build upon the advances already achieved.

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)

Autonomic dysfunction and Eaton Lambert syndrome

Autonomic dysfunction associated with Eaton Lambert syndrome in a patient with oat cell carcinoma of the lung is reported. Widespread postganglionic adrenergic and cholinergic defects suggested the presence of autonomic neuropathy. Clinical remission accompanied tumor regression after combined chemotherapy and radiation.