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J Viallet

Publications and source records attributed to J Viallet.

At least 19 recordsLinked to original sources
PubMed1995

Elevated DNA repair capacity is associated with intrinsic resistance of lung cancer to chemotherapy.

Non-small cell lung cancer (N-SCLC) is generally unresponsive to chemotherapy even without previous drug treatment, as opposed to small cell lung cancer (SCLC), which is initially responsive to chemotherapy. The mechanisms of this intrinsic resistance are unknown. This study was designed to investigate the role of DNA repair in intrinsic resistance of N-SCLC to cisplatin. A panel of primary N-SCLC cell cultures and established cell lines were examined and compared to SCLC cell lines established previously from untreated patients. The overall DNA repair capacity was estimated by the ability of cells to reactivate the pRSV-CAT plasmid damaged by cisplatin ("host cell reactivation" assay). Cytotoxicity was determined for cisplatin in vitro. N-SCLC cells were found to be significantly more resistant to cisplatin than SCLC cell lines isolated from untreated patients (P < 0.01). The capacity of N-SCLC cells to reactivate pRSV-CAT plasmid damaged with cisplatin and transfected into cells was higher in N-SCLC cells than in SCLC cells originating from patients who were untreated previously (P < 0.05). Correlation was also observed between chloramphenicol acetyltransferase activity and intrinsic resistance to cisplatin. However, no significant difference was observed between primary N-SCLC cultures and established cell lines. This study indicates that elevated DNA repair capacity is associated with drug resistance in lung cancer and suggests that modulation of DNA repair mechanism(s), such as the incorporation of specific DNA repair inhibitor(s) in therapeutic regimens, may help to improve therapeutic strategies of N-SCLC.

Aged↗
PubMed1995

Expression of the gastrin-releasing peptide receptor confers a growth response to bombesin in immortalized human bronchial epithelial cells.

We have introduced a human gastrin-releasing peptide receptor expression vector into an immortalized human bronchial epithelial cell normally unresponsive to the ligand bombesin. Successfully transfected cells express specific binding sites at a density similar to that found at the surface of human lung cancer cells and show an elevation of intracellular calcium concentration in response to bombesin. We found that cellular strains expressing the receptor showed a growth stimulation in response to bombesin in proportion to cell surface receptor density. We conclude that expression of bombesin receptors contributes to the growth potential of human bronchial epithelial cells.

Animals↗
PubMed1995

Preclinical pharmacology of cholera toxin.

Cholera toxin was selected for pharmacologic evaluation by the National Cancer Institute on the basis of antiproliferative activity against small-cell and non-small-cell lung-cancer cell lines. A feature common to the sensitive cell lines was abundant expression of GM1 ganglioside, the cellular receptor for cholera toxin. A sandwich enzyme-linked immunosorbent assay (ELISA) was developed to quantitate cholera toxin in biological fluids. A sigmoidal relationship was observed between the cholera toxin plasma concentration and the absorbance at 490 nm (OD490) of the product of horseradish peroxidase-catalyzed oxidation of o-phenylenediamine over the range of 6.25-1,600 ng/ml. Logit transformation of the OD490 data was linear over the entire concentration range and assay variability was less than 25%. Cholera toxin was stable in murine and human whole blood and plasma. Following i.v. administration of 1,500 micrograms/kg to male CD2F1 mice, cholera toxin plasma elimination was described by a two-compartment open model. The half-lives (t1/2 alpha, t1/2 beta), plasma clearance, and steady-state volume of distribution were 0.7 min, 49 min, 24 ml min-1 kg-1 912 ml/kg, respectively. Cholera toxin was not detected in plasma following an s.c. dose of 1,500 micrograms/kg. Urinary recovery following intravenous drug administration was less than 0.1%.

Animals↗
PubMed1994

Receptor subtype expression and responsiveness to bombesin in cultured human bronchial epithelial cells.

We detected low level expression of the gastrin-releasing peptide and neuromedin-B receptor mRNAs in cultures of human bronchial epithelium from 4 of 6 individuals. Bombesin receptor subtype-3 mRNA was undetectable in these cells. An elevation of intracellular calcium concentration was observed in response to bradykinin (6 of 6) and neurotensin (1 of 5) but not to bombesin (0 of 6), vasopressin (0 of 6), or cholecystokinin (0 of 3). In contrast, such responses are frequently noted in lung cancer cell lines. Bombesin did not stimulate the in vitro growth of an immortalized human bronchial epithelium cell line expressing low levels of bombesin receptor mRNAs. We conclude that bombesin receptors are expressed at low levels in human bronchial epithelium cells which may acquire greater responsiveness to multiple neuropeptides in the course of multistep carcinogenesis.

Base Sequence↗
PubMed1994

Characterization of human bronchial epithelial cells immortalized by the E6 and E7 genes of human papillomavirus type 16.

We describe a novel human bronchial epithelial cell line immortalized after transfection with the E6 and E7 genes of human papillomavirus type 16. The established HBE4-E6/E7 cell line resembles morphologically the basal cells of the normal human bronchial epithelium and is nontumorigenic. A clonal isolate proved to be more sensitive to terminal differentiation induced by phorbol esters than the parental line, but both are refractory to the effects of serum. HBE4-E6/E7 cells are able to form tubules when grown in a basement membrane-like matrix, indicating that the cellular pathways leading to immortalization and those governing morphogenesis are distinct. This cell line should prove useful in the study of bronchial epithelial cell growth, differentiation, morphogenesis, and carcinogenesis.

Bronchi↗
PubMed1994

Unique catalytic properties dictate the enhanced function of p59fynT, the hemopoietic cell-specific isoform of the Fyn tyrosine protein kinase, in T cells.

As a result of alternative splicing, the fyn gene encodes two different tyrosine protein kinase isoforms. While one protein (p59fynB) is abundantly expressed in the brain, the alternative product (p59fynT) is contained only in cells of hemopoietic lineages, especially T lymphocytes. Sequence analyses have revealed that these two isoforms differ exclusively within a stretch of 52 amino acids which overlaps the end of the Src homology 2 (SH2) motif and the beginning of the catalytic domain. Consistent with the idea that FynT provides a specialized function in hemopoietic cells, we have previously shown that expression of activated FynT molecules, but not that of activated FynB polypeptides, enhanced the antigen responsiveness of a mouse T-cell line (BI-141) (D. Davidson, L. M. L. Chow, M. Fournel, and A. Veillette, J. Exp. Med. 175:1483-1492, 1992). In this study, we examined the basis for the distinct signalling capabilities of the two Fyn isoforms in T lymphocytes. Our biochemical analyses revealed that FynT is more adept than FynB at promoting antigen receptor-triggered calcium fluxes. This phenomenon likely contributes to the improved biological function of FynT during antigen stimulation, as the calcium ionophore ionomycin partially rescued the inability of FynB to enhance antigen-induced lymphokine secretion. To establish the structural basis for these observations, we also created and analyzed a series of chimeras of FynT and FynB. These studies demonstrated that the distinct catalytic domain of FynT, and not its altered SH2 motif, is responsible for the improved ability to augment antigen responsiveness. Similarly, this sequence enhances the ability to mobilize cytosolic calcium in response to antigen receptor stimulation. Taken together, these data show that the distinct biological impacts of FynT and FynB in T cells are related to limited structural differences in the amino-terminal portion of their catalytic domains and that they reflect, at least in part, the greater ability of FynT to mobilize cytoplasmic calcium.

Alternative Splicing↗
PubMed1994

Vinorelbine (Navelbine) in the adjuvant and neoadjuvant treatment of non-small cell lung cancer.

Several Canadian centers are studying the favorable activity and toxicity profile of vinorelbine (Navelbine; Burroughs Wellcome Co, Research Triangle Park, NC; Pierre Fabre Médicament, Paris, France) in current and future trials of adjuvant and neoadjuvant treatment of non-small cell lung cancer. In locally advanced, unresectable disease, the 10-week regimen in cisplatin 100 mg/m2 during weeks 1 and 5, vinorelbine 30 mg/m2 weekly for 5 weeks with a 50% dose reduction planned for week 2 only, and accelerated fractionation thoracic irradiation during weeks 7 to 10 (30 fractions of 2 Gy in 4 weeks, once daily during weeks 7 and 8, and twice daily during weeks 9 and 10). Preliminary data on 17 patients who have completed treatment to date show it has been well tolerated, with only four cases of grade 3 nonhematologic toxicities. Favorable results from combined therapy with cisplatin and vinorelbine in advanced disease have led the National Cancer Institute of Canada Clinical Trials Group to consider testing adjuvant cisplatin and vinorelbine in completely resected non-small cell lung cancer. Surgically staged patients with T2, N0 and T1-2N1 tumors will be stratified according to nodal status and presence or absence of ras oncogene mutations in resected tumor DNA. Patients will be randomized to observation or a 16-week trial of adjuvant chemotherapy with cisplatin 50 mg/m2 days 1 and 8 every 4 weeks during the 16 weeks, and vinorelbine 30 mg/m2 weekly for 16 weeks. All resected tumors will be banked for further correlative studies to identify a clinically meaningful panel of molecular prognostic markers.

Antineoplastic Agents↗
PubMed1993

BRS-3: a novel bombesin receptor subtype selectively expressed in testis and lung carcinoma cells.

The bombesin (BN)-like peptides mediate a diverse spectrum of biological activities and have been implicated as autocrine growth factors in the pathogenesis and progression of some human small cell lung carcinoma tumors. Previously, two mammalian BN-like peptide receptor subtypes, gastrin-releasing peptide receptor and neuromedin-B receptor, have been cloned and characterized. In this study, we have isolated and characterized human genomic and complementary DNA (cDNA) clones encoding a new BN-like peptide receptor subtype, BN receptor subtype 3 (BRS-3). Expression of BRS-3 cDNA in Xenopus oocytes encodes a functional receptor that is specifically activated by BN-like peptides. Chromosome mapping studies indicate that the BRS-3 gene is located on human chromosome X. BRS-3 mRNA expression in rat tissues is limited to secondary spermatocytes in testis. In contrast, BRS-3 mRNA is widely expressed in a panel of human cell lines from all histological types of lung carcinoma. These results suggest a role for BN-like peptides and their receptors in mammalian reproductive physiology and also indicate that BRS-3 could serve as a potential therapeutic target for human lung carcinoma.

Amino Acid Sequence↗
PubMed1993

Protein kinase C is not involved in the homologous desensitization of bombesin responses in small cell lung cancer cells.

Homologous desensitization of responses to bombesin in small cell lung cancer cells can be mimicked by protein kinase C-activating phorbol esters. We show that phorbol ester-induced desensitization can be blocked by prior treatment with the protein kinase C inhibitor staurosporine or prolonged pretreatment with phorbol esters. However, under these conditions, homologous desensitization to bombesin persists. These data indicate that phorbol ester-induced desensitization is distinguishable from bombesin-induced homologous desensitization. Protein kinase C is not a dominant component in the homologous desensitization to bombesin in small cell lung cancer cells.

Alkaloids↗
PubMed1993

Expression of c-myc in progenitor cells of the bronchopulmonary epithelium and in a large number of non-small cell lung cancers.

We performed in situ hybridization for c-myc, N-myc, and L-myc mRNA expression using 35S-labeled cRNA probes on frozen sections of 19 pairs of non-small cell lung cancers (NSCLC) and the surrounding non-neoplastic lung tissue. In non-neoplastic lung, c-myc expression was strongest in bronchial epithelium basal cells and hyperplastic alveolar type II pneumocytes, which are potential progenitor cells for bronchopulmonary epithelium and their tumors. In contrast, N-myc and L-myc mRNAs were not detected in non-neoplastic lung. In studies of freshly resected primary tumors, expression of c-myc was detected in 11 of 19 NSCLC (with the highest levels in squamous cell carcinomas), two of which also expressed L-myc, while N-myc expression was never detected. Levels of c-myc expression in tumors were significantly higher than in non-neoplastic lung samples. We conclude that: (1) c-myc expression in non-neoplastic lung tissues is highest in bronchial basal cells and hyperplastic type II cells, and (2) in NSCLC, overexpression of the myc-proto-oncogene is common.

Blotting, Northern↗
PubMed1992

Growth inhibition by cholera toxin of human lung carcinoma cell lines: correlation with GM1 ganglioside expression.

The effect of cholera toxin (CT) on the growth of 12 small cell lung carcinoma (SCLC) and 15 non-small cell lung carcinoma (NSCLC) cell lines is presented. CT inhibited the growth of nine SCLC cell lines (concentration for 50% inhibition of growth, 27-700 ng/ml), all of which had abundant expression of GM1 ganglioside, the surface receptor for CT. CT-resistant SCLC all had greatly decreased GM1 expression. In contrast, CT inhibited the growth of only four of 15 NSCLC cell lines. Seven of the 11 CT-resistant NSCLC had levels of GM1 comparable to CT-sensitive NSCLC or SCLC. In a limited panel of cell lines, cyclic AMP (cAMP) agonists including forskolin, 8Br[cAMP], and dibutyryl[cAMP] did not consistently reproduce CT-mediated inhibition of cell growth, nor did these compounds overcome resistance of cells to the growth inhibitory effects of CT. Expression of the RI and RII regulatory subunits of cAMP-dependent protein kinase was similar in CT-resistant and CT-sensitive SCLC or NSCLC cell lines. In the presence of isobutylmethylxanthine, intracellular cAMP levels induced by CT in a CT-resistant, GM1(+) NSCLC cell line were comparable to those achieved in a CT-sensitive NSCLC cell line. We conclude that inhibition of lung carcinoma cell growth by CT in all cases requires expression of GM1, and in the case of SCLC cell lines the presence of GM1 is sufficient. In NSCLC cell lines, expression of GM1 is not sufficient for growth inhibition by CT. These findings imply refractoriness to growth inhibition by cAMP in GM1(+), CT-resistant NSCLC cell lines and the possibility of non-cAMP-related mechanisms for growth inhibition in CT-sensitive cell lines.

1-Methyl-3-isobutylxanthine↗
PubMed1991

Two distinct bombesin receptor subtypes are expressed and functional in human lung carcinoma cells.

Bombesin-like peptides have been implicated as autocrine growth factors influencing the pathogenesis and progression of some human lung carcinoma cells. To determine the pharmacologic and structural properties of the bombesin receptors expressed in human lung carcinoma cells, cDNA clones encoding a human gastrin-releasing peptide receptor (GRP-R) and a pharmacologically distinct neuromedin-B preferring bombesin-receptor (NMB-R) were isolated from a human small cell lung carcinoma cell line (NCI-H345). After expression in Xenopus oocytes, a GRP-R-specific antagonist was effective in blocking responses elicited from the cloned GRP-R, but not the NMB-R. Both GRP-R and NMB-R mRNA expression was detected at varying levels in a panel of human lung cancer cell lines. These results indicate heterogeneity of bombesin receptor subtypes exists in human lung carcinoma cells and should be considered in the design of bombesin receptor antagonists intended to inhibit tumor cell growth.

Amino Acid Sequence↗
PubMed1991

ras gene mutations in non-small cell lung cancers are associated with shortened survival irrespective of treatment intent.

We analyzed 66 non-small cell lung cancer cell lines for mutations at codons 12, 13, and 61 of all three ras genes and correlated the findings with patient survival. We used designed restriction fragment-length polymorphisms to detect mutations after amplification of ras-specific sequences by the polymerase chain reaction. We found 19 mutations of ras genes (29%), and 11 of these 19 (58%) were at codon 12 of the K-ras gene. By univariate analysis, the presence of any ras mutation in cell lines from patients who received curative intent treatment was associated with a shorter survival (P2 = 0.002). For patients who received only palliative treatment, detection of K-ras mutations at codon 12 was associated with a shortened survival (P2 = 0.0103), but this analysis was not statistically significant for the group with any ras mutation (P2 = 0.093). The Cox proportional hazards model also predicted a higher risk for patients with any type of ras mutations. We conclude that ras mutations, present in a subset of non-small cell lung cancers, are independently associated with the shortened survival of patients, irrespective of treatment intent.

Analysis of Variance↗
PubMed1991

Mutations of ras genes distinguish a subset of non-small-cell lung cancer cell lines from small-cell lung cancer cell lines.

We screened a panel of 103 human lung cancer cell lines for the presence of point mutations at codons 12, 13 or 61 of the human K-, H- and N-ras genes, using restriction fragment length polymorphisms (RFLP), created through mismatched primers during polymerase chain reaction (PCR) of genomic DNA. We found ras mutations in 22/61 (36%) non-small-cell lung cancer (NSCLC) cell lines, predominantly in K-ras codon 12. Identical mutations were present in uncultured tumor materials corresponding to 11 cell lines containing mutated ras genes. ras mutations were found not only in adenocarcinoma cell lines (9/32, 28%), but also in cell lines derived from other types of NSCLC (13/29, 45%). In contrast, none of 37 small-cell lung cancer (SCLC) cell lines and five extra-pulmonary small-cell cancer cell lines had ras mutations. ras mutations were not correlated with sex of the patients, tumor extent, prior therapy status or in vitro culture time. G to T or A to T transversions were the most common base substitutions, occurring in codons 12 and 61 respectively. We conclude that ras mutations play a role in the pathogenesis of a subset of NSCLC but are not involved in SCLC.

Alleles↗
PubMed1990

Effect of guanine and adenine nucleotides on bombesin-stimulated phospholipase C activity in membranes from Swiss 3T3 and small cell lung carcinoma cells.

In [3H]inositol-labeled membranes prepared from Swiss mouse 3T3 and human small cell lung carcinoma cells, [Tyr4]-bombesin stimulated production of water-soluble inositol phosphates. The reaction was stimulated by guanosine 5'-O-[3-thiotriphosphate] and was specifically inhibited by both [Leu13-psi-CH2NHLeu14]-bombesin and the antibombesin antibody 2A11. [Tyr4]-bombesin-induced activation of phospholipase C is most apparent in Ca2(+)-depleted conditions (less than 1 microM[Ca2+]free). The kinetics of activation by ligand also demonstrate that [Tyr4]-bombesin-dependent phospholipase C activation is most apparent at [Mg2+]free of approximately 0.2 microM. At millimolar concentrations of [Mg2+]free, there is considerably less dependence on [Tyr4]-bombesin for activation of phospholipase C. ATP is not necessary for initial activation of phospholipase C, and beta, gamma-imidoadenosine-5'-triphosphate does not inhibit the reaction. These results demonstrate that in these cell types [Tyr4]-bombesin activates phospholipase C in conjunction with guanine nucleotides. Phospholipase C-coupled guanine nucleotide regulatory proteins would be appropriately considered as novel targets for the development of therapeutic strategies in small cell lung carcinoma.

Adenosine Triphosphate↗
PubMed1990

Dominant oncogenes and tumor suppressor genes in the pathogenesis of lung cancer.

An understanding of the molecular pathogenesis of lung cancer has evolved from classic cytogenetic studies and the use of restriction fragment length polymorphisms to encompass the definition of specific genetic abnormalities associated with this disease. Activation of the dominant class of oncogenes is frequent, with involvement of the ras and myc families of genes being the best defined. Several examples of inactivation at specific loci exist and have been related to the presence of tumor suppressor genes, most notably the retinoblastoma gene, p53, and a putative gene located on the short arm of chromosome 3. As our understanding of the nature and interactions between these numerous genetic events evolves, new opportunities for early diagnosis, prevention, and treatment will arise.

Animals↗
PubMed1990

Cholera toxin inhibits signal transduction by several mitogens and the in vitro growth of human small-cell lung cancer.

Cholera toxin (CT) inhibited the in vitro growth of three of four human small-cell lung carcinoma (SCLC) cell lines with a 50% inhibitory concentration of 27-242 ng/ml. Loss of surface membrane ruffling and the capacity of [Tyr4]-bombesin, vasopressin, and fetal calf serum to stimulate increases in intracellular free calcium clearly preceded effects on cellular metabolic activity and cell growth. 125I-[Tyr4]-bombesin binding was unaffected by CT treatment but [Tyr4]-bombesin stimulated phospholipase C activity was decreased in membranes from CT-treated SCLC cells. CT stimulated a rapid but transient increase in intracellular cyclic AMP ([cAMP]i) in SCLC. The effects of CT on susceptible SCLC were not reproduced by elevations of [cAMP]i induced by forskolin or cyclic AMP analogues. GM1 ganglioside, the cellular binding site for CT, was highly expressed in the CT-sensitive but not the CT-resistant SCLC cell lines. In contrast, expression of guanine nucleotide binding protein substrates for ADP-ribosylation by CT was similar. These data demonstrate the existence of a CT-sensitive growth inhibitory pathway in SCLC-bearing GM1 ganglioside. Addition of CT results in decreased responsiveness to several mitogenic stimuli. These results suggest novel therapeutic approaches to human SCLC.

Adenosine Diphosphate Ribose↗