Antitumor activity of magainin analogues against human lung cancer cell lines.

Magainin 1 and magainin 2, originally isolated from African clawed frog Xenopus laevis skin, inhibit the growth of bacteria and fungi. Synthetic magainin A (MAG A) and magainin G (MAG G) are more potent against bacteria and protozoa. In order to determine the antitumor activity of these analogues, we have tested these two analogues against six small cell lung cancer (SCLC) cell lines NCI-H82, NCI-H526, NCI-H678, NCI-H735, NCI-H841, and NCI-H889, which were known to differ by more than 10-fold in their sensitivity to different chemotherapeutic agents, and four normal human fibroblast cell lines. Semiautomated 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays of the six SCLC cell lines revealed average concentrations producing 50% inhibition (IC50) values of 2.6 microM (range, 0.49-9.30 microM) for cisplatin, 2.5 microM (range, 0.39-6.00 microM) for etoposide, and 138.8 nM (range, 55.0-450.0 nM) for doxorubicin. The average IC50 of MAG A was 8.64 microM (range, 6.23-11.7 microM) and that of MAG G was 8.82 microM (range, 4.44-12.5 microM) against the SCLC cell lines. Despite a 10-fold difference in sensitivity to standard chemotherapeutic agents, the IC50 of MAG A and MAG G differs by less than 3-fold. The average IC50 against four normal human fibroblast cell lines was 21.1 microM (range, 12.7-25.6 microM) for MAG A and 29.2 microM (range, 21.3-34.8 microM) for MAG G. Combined exposure to the IC50 concentration of MAG A or MAG G plus IC50 of etoposide or cisplatin decreased the percentage of surviving SCLC cells to 29.0% (range, 26.1-31.7%). MAG A or MAG G had an additive effect when used with standard chemotherapeutic agents. These data suggest that MAG A and MAG G have in vitro antitumor activity against SCLC cell lines.     

In vitro growth inhibition of human small cell lung cancer by physalaemin

Production and secretion of neuroendocrine peptides by small cell lung cancer (SCLC) has been detected in the past years. Most recently the role of bombesin as an autocrine/paracrine growth modifier has been demonstrated. We used the soft agarose clonogenic assay to evaluate the influence of other neuroendocrine peptides on the in vitro proliferation of SCLC cell lines. Neuroendocrine peptides tested were adrenocorticotropic hormone, arginine vasopressin, calcitonin, glucagon, kassinin, neurotensin, physalaemin, somatostatin, and substance P. Experiments were carried out in serum-free and serum-supplemented media with and without serum-free incubation periods. Our results indicated that the amphibian undecapeptide physalaemin inhibits the clonal and mass culture growth of SCLC cell lines at picomolar concentrations. All other neuroendocrine peptides failed to influence SCLC growth in the test systems used. These results suggest a growth regulating effect of physalaemin and a potential new form of neuroendocrine peptide therapy for SCLC.     

In vitro chemosensitivity of human lung cancer cell lines

Human lung cancer cell lines, established from patients with both small cell cancer (SCLC) and non-small cell cancer (non-SCLC; squamous cell, large cell, anaplastic, and adenocarcinoma), were tested for their in vitro chemosensitivity to a panel of drugs. Drug sensitivity was assayed by either soft agar clonogenicity or a novel dye-exclusion assay. Eleven non-SCLC lines (eight continuous, three recently cultured) and five SCLC lines (all continuous) were tested. Four of eight continuous non-SCLC lines cloned sufficiently to permit limited in vitro drug testing, as did two of the five SCLC lines. All 16 cell lines could be tested for multiple drugs using the dye-exclusion assay. Drug concentrations for the nonclonogenic assay more closely approximated the area under the concentration-time curve for a given concentration of each agent. There was considerable variation in the relative sensitivity of the cell lines and the patterns of individual drug sensitivity. The majority of non-SCLC cell lines were refractory to most drugs. Cell lines derived from two previously treated SCLC patients and from three untreated SCLC patients showed greater sensitivity. Concurrent clonogenic and dye-exclusion assays showed similar drug rankings but different absolute values for percent survival. The nonclonogenic dye-exclusion assay is more rapid than the soft agar clonogenic assay (4 days vs. 2-3 weeks), could be performed on all cell lines tested, and appears to reflect the clinical diversity of human lung cancer.     

Molecular analysis of the short arm of chromosome 3 in small-cell and non-small-cell carcinoma of the lung

Previous studies have suggested that the loss of DNA sequences on the short arm of chromosome 3 (3p) is associated with small-cell lung carcinoma. We therefore looked for loss of 3p alleles in tumor tissue from 42 patients with either small-cell or non-small-cell lung carcinoma. All 13 patients with small-cell lung carcinoma who were heterozygous for one or more alleles at 3p in normal tissue had the loss of at least one codominant allele in the tumor tissue. Cell lines of small-cell lung carcinoma from an additional eight patients were homozygous for 3p alleles; this result was significantly different from the predicted frequency of homozygosity. The tumor tissue studied included cell lines of small-cell lung carcinoma obtained from biopsy specimens, an autopsy sample, and an excised lymph node containing tumor cells. Loss of alleles at 3p was observed in tumor samples obtained before and after chemotherapy. Four of 15 evaluable patients with non-small-cell carcinoma of the lung had loss of 3p alleles. We conclude that loss of alleles at 3p is a change found consistently in small-cell lung carcinoma and occasionally in non-small-cell lung carcinoma.     

Radioimmunodetection of cutaneous T-cell lymphoma with 111In-labeled T101 monoclonal antibody

T101 monoclonal antibody recognizes a pan-T-cell antigen present on normal T cells and also found in high concentrations in cutaneous T-cell lymphoma. We used this antibody, radiolabeled with 111In, in gamma-camera imaging to detect sites of metastatic cutaneous T-cell lymphoma in 11 patients with advanced disease. In all patients, [111In]T101 concentrated in pathologically or clinically detected nodes, including those in several previously unsuspected nodal regions. Concentrations (per gram of tissue) ranged from 0.01 to 0.03 percent of the injected dose and were consistently 10 to 100 times higher than previously reported on radioimmunodetection. Focal uptake was seen in skin tumors and heavily infiltrated erythroderma but not in skin plaques. The specificity of tumor targeting was documented by control studies with [111In]chloride or [111In]9.2.27 (anti-melanoma) monoclonal antibody. Increasing the T101 dose (1 to 50 mg) altered distribution in nontumor tissues. These studies suggest that imaging with [111In]T101 may be of value in identifying sites of cutaneous T-cell lymphoma. In contrast to the targeting of solid tumors, the mechanism of localization appears to be related to binding to T cells, which can then carry the radioactivity to involved sites.     

Current status of small peripheral adenocarcinomas of the lung and their importance to pathologists

There has been a large amount of work done recently on small peripheral stage I adenocarcinomas that come to resection. Radiological (including proportion of ground glass opacity) and pathological features of these lesions (predominant bronchioloalveolar component, central scar with or without invasion <0.5 cm) have been shown to be prognostically favorable with cure rate approaching 100% in some series. Most of these studies emanate from Japan. The relevance of these studies to other parts of the world, particularly North America, is discussed in light of the fact that some recent chemotherapeutic studies with gefitinib have shown increased response in individuals of Asian origin, suggesting that some genetic differences may be significant. The relevance of these findings to pathologists and the pathological study of small peripheral adenocarcinomas from elsewhere in the world are discussed.     

Expression of surfactant associated protein-A and Clara cell 10 kilodalton mRNA in neoplastic and non-neoplastic human lung tissue as detected by in situ hybridization.

Two markers for the progenitor cells of peripheral airways and their tumors are the 10 kilodalton (kd) Clara cell protein and the major surfactant associated protein-A (SP-A). We used the RNA-RNA in situ hybridization technique to study expression of the genes encoding these proteins at the cellular level in 19 pairs of non-neoplastic and neoplastic tissues from resected human lungs. Our results show that in non-neoplastic lung tissue, the Clara 10 kd protein gene was expressed in nonciliated cells of both bronchial and bronchiolar epithelium, indicating that, in contrast to previous assumptions, cells with Clara cell-like differentiation in humans may not be restricted to bronchiolar cells. The incidence of Clara 10 kd protein gene expression, as detected in lung carcinomas (1 out of 19 cases positive) was less than expected based on previous ultrastructural reports. The SP-A gene was strongly expressed in normal alveolar type II cells in non-neoplastic lung and, at higher levels, in hyperplastic cells. In addition, SP-A mRNA expression was observed in scattered bronchial and bronchiolar epithelial cells in 40% of the airways examined. Five out of 17 lung tumors, all of which were adenocarcinomas, were positive for SP-A expression, albeit generally less intense than type II cells. This expression was seen in carcinomas with papillolepidic as well as solid and glandular growth patterns. Our findings provide new insights into the peripheral airway cell differentiation.     

Neuroendocrine differentiation in endocrine and nonendocrine lung carcinomas

Bronchial carcinoids and small cell lung cancer (SCLC) are currently recognized as neuroendocrine (NE) neoplasms. However, non-SCLC (NSCLC) may also express NE properties. Paraffin-embedded sections of a comprehensive panel of 113 lung carcinomas were analyzed for the expression of three general markers common to all NE cells, namely, chromogranin A, Leu-7 and neuron-specific enolase (NSE), five specific NE secretory products, and four other tumor markers by immunohistochemistry using the sensitive avidin-biotinylated peroxidase technique. The authors were able to demonstrate the following: (1) most, but not all carcinoids and SCLCs expressed multiple NE markers in a high percentage of tumor cells; (2) up to a half of NSCLC cases contained small subpopulations of cells expressing NE in a high percentage of tumor cells; (2) up to half of NSCLC cases contained small subpopulations of cells expressing NE markers; and (3) occasional NSCLCs showed staining patterns indistinguishable from SCLC. Specifically, 7 of 77 NSCLCs expressed four or more NE markers. NE markers in NSCLCs were more commonly expressed in adenocarcinomas and large cell carcinomas and rarely in squamous cell carcinomas. For comparison, the mean number of NE markers expressed by all cases of NSCLC was 1.5, carcinoids 6.0, and SCLCs 3.8. Individual "marker counts" were not useful in categorizing lung tumors as carcinoids and SCLC versus NSCLC. Instead, 95% of the tumors were correctly classified, applying a statistical model created from staining indices of the three general NE markers (chromogranin A, Leu-7, NSE) and three other tumor markers (carcinoembryonic antigen, keratin, vimentin). Because NSCLCs with NE features might have different clinical characteristics than other NSCLCs, immunohistochemistry provides an effective manner to identify this biologically interesting subset of NSCLCs in routine paraffin sections.