Human SCLC Cell Research Articles

MRP gene overexpression in a human doxorubicin-resistant SCLC cell line: Alterations in cellular pharmacokinetics and in pattern of cross-resistance

MRP gene overexpression in a human doxorubicin-resistant SCLC cell line: Alterations in cellular pharmacokinetics and in pattern of cross-resistance

Intracerebral and subcutaneous xenografts of human SCLC in the nude rat: comparison of monoclonal antibody localization and tumor infiltrating lymphocytes

In the WAG/Rij nude rat, subcutaneous (s.c.) and intracerebral (i.c.) xenografts of the human SCLC cell line GLC-28 were evaluated for their growth behavior, in vivo monoclonal antibody binding and presence of tumor infiltrating lymphocytes. For the i.c. xenografts, two models of cerebral tumor growth were studied, one in the cerebral cortex and one in the lateral ventricle of the brain. In the s.c. and both i.c. xenografts models, in vivo localization of anti-carcinoma moab MOC-31 occurred within 4 hours after i.p. injection, with a maximal binding at 24 h after injection. A pronounced tumor infiltration of predominantly NK cells was observed for s.c. and intraventricular xenografts, but not for the GLC-28 tumors xenografted in the cerebral cortex. The presented nude rat/GLC-28 xenograft models may be used for the in vivo testing of experimental imaging techniques or alternative treatment strategies relevant to brain metastases of human SCLC.

Tumor-cell killing by MAbs against fucosyl GM1, a ganglioside antigen associated with small-cell lung carcinoma.

Monoclonal antibodies (MAbs) reactive with the ganglioside fucosyl GM1 (Fuc-GM1), an antigen associated with small-cell carcinoma of the lung (SCLC), were tested for their ability to mediate tumor-cell killing in vitro in conjunction with humoral and cellular effectors and to inhibit tumor engraftment in nude mice in vivo. MAbs F12 and F15, both IgG3k, induced human complement-mediated cytolysis of 3 Fuc-GM1-expressing tumor cell lines: one rat hepatoma cell line, H4-II-E, and 2 human SCLC cell lines, NC1 H69 and NC1 H128. F12 and F15 also induced ADCC of these cell lines in the presence of either murine or human effector cells. Addition of sub-cytolytic amounts of fresh human serum as complement source resulted in enhanced ADCC induced by MAb F12 (IgG3). Also a Fuc-GM1-reactive MAb of IgM isotype, F9, was able to induce such complement-aided ADCC (CADCC). F12 and F15 both proved to effectively inhibit engraftment of H4-II-E tumors in nude mice. A single dose of a modest amount (40 micrograms) of MAb conferred 65 to 100% protection against development of tumors. Our results demonstrate that Fuc-GM1 can act as a target antigen on tumor cells for specific immunotherapy in vitro and in a mouse model in vivo. Complement and murine and human mononuclear effector cells were effective mediators of tumor cytolysis in vitro in the presence of murine Fuc-GM1-reactive MAbs. Our results also suggest that humoral and cellular effectors may co-operate in specific tumoricidal reactions and that these may be induced by antibodies of both IgG and IgM isotypes.

Gastrin releasing peptide antagonists with improved potency and stability

Gastrin releasing peptide (GRP) is a 27 amino acid peptide hormone which is homologous to the amphibian peptide bombesin. Two series of novel GRP antagonists were developed by C-terminal modification of N-acetyl-GRP-20-27 amide. Peptide derivatives within each series resist enzymatic degradation in serum and exhibit strong affinity for the GRP receptor. The first series of compounds replaces the Leu26-Met27 region of GRP with an alkyl ether N-acetyl-GRP-20-25-NH-[(S)-1-ethoxy-4-methyl-2-pentane], specifically blocked radiolabeled GRP binding with an IC50 of 6 nM. In the second series of antagonists the oxygen of the ether moiety is replaced with a methylene group, resulting in GRP antagonists which are equipotent to native GRP in receptor binding assays (IC50 = 2 nM) and are also resistant to proteolytic degradation in vitro. All of the C-terminally modified peptides tested blocked GRP-stimulated mitogenesis in Swiss 3T3 mouse fibroblasts. Representative compounds also blocked GRP-induced elevation of [Ca2+]i in human SCLC cells, and inhibited GRP-independent release of gastrin in vivo.

Characterization of VIP- and helodermin-preferring receptors on human small cell lung carcinoma cell lines

We investigated the molecular and pharmacologic characteristics of VIP receptors on two human SCLC cell lines: NCI-N592 and NCI-H345. With NCI-N592 cell, the order of potency of VIP-related peptides in inhibiting 125I-VIP binding and in stimulating cAMP production was typical of the human VIP receptor. By covalent cross-linking, a polypeptide of Mr 62,300 was obtained. Conversely, the behavior of NCI-H345 cell line was totally different: helodermin was the most potent peptide, VIP and PHI were equipotent, while hGRF and secretin were totally ineffective. These results suggest that NCI-N592 cells possess a typical VIP receptor while NCI-H345 cells possess a helodermin-preferring receptor, and that the natural target of helodermin might not be the VIP receptor.

Mechanisms for acquired cytotoxic drug resistance in human small cell lung cancer and the potential utilization of resistance modifiers — A review with focus on in vitro studies

A major obstacle in treatment of SCLC patients is the fact that almost all patients will develop a reduced response to cytotoxic drugs. SCLC is heterogenous for the majority of studied markers, most likely also involving the mechanisms for drug resistance. SCLC has severe genetic alterations, thus with the potential of continuously alternating phenotypic properties, including drug resistance. This review describes some possible mechanisms for impaired response to cytotoxic drugs in human SCLC cell lines. The SCLC cell lines demonstrate development of drug resistance involving several mechanisms: decreased intracellular drug concentration, increased detoxification and DNA repair and decreased DNA strand breaks. Furthermore, the MDR resistance in the SCLC cell lines seems to be unrelated to the Pgp expression. Despite this, response modifiers like verapamil and cyclosporin A, suggested to mediate their effects through inhibition of Pgp, may become of importance in the reversal also of SCLC cytotoxic drug resistance. The use of ‘non-cross resistant’ drugs like doxorubicin and cisplatin seems reasonable, since these drugs may have different mechanisms for drug resistance.

β-endorphin and neurotensin stimulate in vitro clonal growth of human SCLC cells

Les petites cellules de carcinome de poumon (SCLC) produisent des neuropeptides qui sont capables de reguler leur propre croissance comme cela a deja ete demontre avec la bomberine. L'experience realisee sur des lignees de SCLC montre que des petites doses de neurotensine et β endorphine, dont on a identifie les recepteurs a la surface des cellules, sont aussi capable de stimuler la croissance clonale de SCLC. D'autre part, de faibles doses de Naloxone inhibent la croissance des SCLC malgre la liberation de β endorphine, ce qui suggere que cette derniere agit par des recepteurs sensibles aux opiaces

Characteristics of a multicopy gene family predominantly consisting of processed pseudogenes

The monoclonal antibody MOC-32 detected a 40 kDa protein in Western blot analysis. Immunological screening of an expression library of human SCLC cells with MOC-32 led to the isolation of overlapping cDNA clones. One of these, cHD4, was 1.0 kbp long and of about the same size as its corresponding mRNA. Preceded by an in phase stop codon, an open reading frame of 885 bp was present in cHD4 and a translational product of only 33 kDa could be calculated. Biochemical and immunological analysis established the relationship between the 40 kDa antigen and the isolated coding sequences and resolved the apparent discrepancy between the calculated molecular weight and the observed electrophoretic mobility. Nucleotide sequence comparison of cHD4 to the EMBL database revealed that cHD4 was nearly identical to a sequence claimed to encode a laminin binding protein. Southern blot and nucleotide sequence analysis indicated the presence of multiple copies of the gene in the human genome. At least five of these appeared to represent processed pseudogenes.

Intermediate filament proteins in classic and variant types of small cell lung carcinoma cell lines: A biochemical and immunochemical analysis using a panel of monoclonal and polyclonal antibodies

The intermediate filament protein (IFP) characteristics of a panel of lung cancer cell lines including adenocarcinoma (two cell lines) and small cell lung cancer (SCLC, three classic and three variant cell lines) were examined using one- and two-dimensional gel electrophoretic techniques, immunocytochemical techniques and immunoblotting assays. A panel of 28 monoclonal and polyclonal antibodies to the five different types of IFP were used. The results of our studies indicate that these human lung adenocarcinoma, classic SCLC and variant SCLC cell lines can be differentiated on the basis of their pattern of IFP. The main conclusions from this study can be summarized as follows. The two adenocarcinoma cell lines contain cytokeratins 7, 8, 18, and sometimes 19, next to vimentin intermediate filament (IF). The three classic-type SCLC cell lines contain only cytokeratin IFs but not vimentin IF or neurofilaments (NFs). Cytokeratin polypeptides 7, 8, 18 and 19 could be detected. All three variant-type SCLC cell lines do not contain detectable amounts of cytokeratins. In contrast, two out of three variant SCLC cell lines contain neurofilament proteins. All three variant-type SCLC cell lines contain vimentin IF. Using immunoblotting assays with monoclonal and polyclonal antibodies to defined NF proteins the presence of the 68 X 10(3) Mr and the 160 X 10(3) Mr NF polypeptide could be demonstrated in two variant SCLC cell lines. As patients with SCLC-variant phenotype have a poorer prognosis after cytotoxic therapy than patients with 'pure' SCLC, the use of antibodies to IFP in staining fresh lung tumours, especially anaplastic ones, may differentiate the two subtypes of SCLC. Such a distinction would have a major impact on therapy selections and may be of prognostic importance.