c-Jun activation is required for 4-hydroxytamoxifen-induced cell death in breast cancer cells.

The c-Jun N-terminal kinase (JNK) has been shown to mediate tamoxifen-induced apoptosis in breast cancer cells. However, the downstream mediators of the JNK pathway linking tamoxifen to effectors of apoptosis have yet to be identified. In this study, we analysed whether c-Jun, the major nuclear target of JNK, has a role in tamoxifen-induced apoptosis of SkBr3 breast cancer cells. We show that before DNA fragmentation and caspase 3/7 activation, cytotoxic concentrations of 4-hydroxytamoxifen (OHT) induced JNK-dependent phosphorylation of c-Jun at JNK sites earlier shown to regulate c-Jun-mediated apoptosis. In addition, OHT induced ERK-dependent expression of c-Fos and transactivation of an AP-1-responsive promoter. In particular, the ectopic expression of dominant-negative constructs blocking either AP-1 activity or c-Jun N-terminal phosphorylation prevented DNA fragmentation after OHT treatment. Furthermore, both c-Fos expression and c-Jun N-terminal phosphorylation preceded OHT-dependent activation of caspase 3-7 in different types of tamoxifen-sensitive cancer cells, but not in OHT-resistant LNCaP prostate cancer cells. Taken together, our results indicate that the c-Jun/c-Fos AP-1 complex has a pro-apoptotic role in OHT-treated cancer cells and suggest that pharmacological boosts of c-Jun activation may be useful in a combination therapy setting to sensitize cancer cells to tamoxifen-mediated cell death.

Combined 4-hydroxy-ifosfamide and vinorelbine treatment in established and primary human breast cell cultures.

BACKGROUND: Vinorelbine and ifosfamide are active drugs against breast cancer, but the best treatment schedule has yet to be defined by preclinical or clinical studies. The antitumor activity of 4-hydroxy-ifosfamide (4-OH-IF), the active form of ifosfamide, and vinorelbine (VNB) and their interaction were investigated in two established breast cancer cell lines (MCF-7 and BRC-230) and in 10 primary breast cancer cultures. MATERIALS AND METHODS: Cytotoxic activity was evaluated by a highly efficient clonogenic assay (HECA). The median-effect principle was applied to evaluate synergistic and antagonistic interactions and the corresponding combination index values were calculated. Cell cycle perturbations were analysed by flow cytometry. RESULTS: In MCF-7 and BRC-230 cell lines the sequence VNB for 4 hours followed by 4-OH-IF for 24 hours produced an antagonistic effect. Conversely, the inverse sequential scheme, 4-OH-IF-->VNB provided synergistic effects on both cell lines. The synergism was associated with a strong block in the G2-M phase. Synergistic activity of 4-OH-IF-->VNB sequence was confirmed in 7 of 10 primary breast cancer cultures. CONCLUSIONS: In conclusion, the sequence 4-OH-IF-->VNB appeared to be the most effective scheme both in established cell lines and in primary breast cancer cultures.

Molecular and biological features of two new human squamous and adenocarcinoma of the lung cell lines.

Two human cancer cell lines were established from metastatic lesions of an adenocarcinoma (RAL) and a squamous cell (CAEP) carcinoma of the lung. The clinical histories of the patients from whom the cell lines were derived are reported. The lines were maintained in continuous culture with doubling times of 65 (RAL) and 50 (CAEP) hours. The RAL and CAEP cell lines, whose morphology and ultrastructural features are presented, showed extensively rearranged karyotypes with modal number of 85 (RAL) and 98 (CAEP). In particular, chromosome 2 pentasomy and several clonal markers were evident in the RAL cells, whereas a telomeric deletion of chromosome 1, del (1)(q32), was observed in the CAEP cells. The morphologic data were confirmed by high expression of specific antigens for each histotype. A marked positivity of the neuron-specific enolase (NSE) levels was evident by immunoenzymatic assays in the cell lines cytosol with respect to those present in the respective patient's sera. No amplification or rearrangements were evident in the CMYC, LMYC, NMYC, INT-2, ERBB2, HRAS, KRAS, MOS, HST-1 genes by Southern blotting analysis in each cell line. Point mutations in exon 1 of KRAS and in exon 7 of TP53 were evident by polymerase chain reaction (PCR)-DNA sequencing in the RAL cell line, whereas no alterations were present in the HRAS and RB genes. The four genes studied did not show point mutations in the CAEP cell line. The RAL cell line was resistant to all the drugs tested, whereas the CAEP cells were sensitive to vinblastine. These cell lines may represent useful experimental models to investigate lung cancer biology and anticancer drug response.

Molecular genetics and in vitro sensitivity of a new human cell line, KKP, from a gastric adenocarcinoma.

A new cancer cell line (KKP) was established from an ascitic effusion of an advanced gastric adenocarcinoma, intestinal type. The line has been maintained in continuous monolayer culture with a doubling time of 48 hours for more than 2 years. KKP cells, whose ultrastructural features are presented, showed an aneuploid DNA content, a modal number of 53 chromosomes, and the presence of one double minute chromosome. The karyotype showed trisomies of chromosomes 7, 12, 13, and 14, tetrasomy of chromosome 18, a reciprocal translocation [t(1;20)(q21;p11.2)], and a [t(4;?)] rearrangement. No amplification or rearrangements were evident in the c-MYC, c-ERB B2, H-RAS, INT-2, HST-1, c-MOS, and K-RAS genes, whereas somatic rearrangements were present in the sequences corresponding to c-MET and cyclin E genes by Southern blotting analysis. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis of P53 and RB genes did not reveal alterations or point mutations in the SSCP pattern of conformers. The chemosensitivity pattern assay of the KKP cell line indicated that it was sensitive to cisplatin, etoposide, and doxorubicin and resistant to 4'-hydroperoxycyclophosphamide. The clinical history of the patient from whom the cell line was derived is reported and compared with the results observed in the cell line in vitro. High levels of the tumor-associated antigens CEA (carcinoembryonic antigen) and CA19-9 were evident in the KKP cytosol, whereas the KKP spent culture medium maintained the same low levels of CEA and CA 19-9 found in the patient's serum. This new cell line may represent a useful tool for studying the biology of gastric cancer and for planning new therapeutic approaches.

Chromosomal alterations, biological features and in vitro chemosensitivity of SCLC-R1, a new cell line from human metastatic small cell lung carcinoma.

A new human cancer cell line was established from a metastatic lesion of a small cell lung carcinoma (SCLC-R1) and maintained in continuous culture with a doubling time of 62 h. The SCLC-R1 line, whose ultrastructural features are presented, showed a diploid DNA content, a translocation involving chromosome 16 [t(16;?)(q24;?)] and noticeable deletions in the FHIT (fragile histidine triad) region in the short arm of chromosome 3 [del(3)(p14)] and in the telomeric region of the short arm of chromosome 12 [del(12)(p13)]. The involvement of 12p in metastatic small cell lung cancer is reported here for the first time. No amplification or rearrangements were evident in the c-myc, L-myc, N-myc, int-2, c-erbB-2, H-ras, K-ras, c-mos, and hst-1 genes by Southern blot analysis. Wild-type p53, RB, K-ras and H-ras genes were evident by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis. The neuron specific enolase (NSE) level was much higher in the cell line's cytosol than in the patient's serum and the cell line also had high expression of chromogranin A and cytokeratin 19. SCLC-R1 cells were sensitive to cisplatin, carboplatin and doxorubicin. The clinical history of the patient from whom the cell line was derived is reported. The characteristics of this new cell line indicate it to be a useful experimental model to investigate lung cancer biology and anticancer drug response.

Establishment and characterization of two new cell lines derived from human metastatic breast carcinomas.

Two human cancer cell lines (MA 2 and MA 3) were established from pleural effusions of infiltrating ductal carcinomas of the breast. The lines were maintained in continuous monolayer culture with doubling times of 70 (MA 2) and 78 (MA 3) hr for more than two years and possessed extensively rearranged abnormal karyo-types with modal chromosome number of 83 (MA 2) and 81 (MA 3) and DNA index values of 1.65 and 1.77, respectively. No amplifications or rearrangements were evident in the c-myc, int-2, c-erb B2, c-Ha-ras, or hst 1 genes in MA 2 and MA 3 cell lines. The clinical histories of the patients from whom the cell lines were derived are reported and compared with the results observed in the cell lines in vitro. The presence of CEA, CA 15-3, and MCA tumor markers observed in the primary tumor tissues was retained by the established cell lines. While the primary tumor tissues were ER+/PgR borderline+ (MA 2) and ER-/PgR+ (MA 3), the MA 2 line was ER+/PgR- and the MA 3 line remained ER-/PgR+. The MDR P-glycoprotein was not expressed either in primary tumor tissues or in the respective cell lines. High expression of cytokeratins 7, 18, and 19 was evident by immunohistochemical analysis in each cell line. whereas cytokeratins 8 and 17 were poorly or not at all expressed. The treatment history of the patients from whom the cell lines were derived involved CMF followed six months later by novantrone and cisplatin plus VP 16 (MA 2) and FEC followed four years later by CMF (MA 3). The chemosensitivity pattern assay of the cell lines indicated that the MA 2 line was sensitive to doxorubicin, cisplatin, and vinblastine, whereas the MA 3 line was sensitive to doxorubicin and cisplatin. The characteristics of these cell lines indicate them to be a good experimental model to investigate breast cancer biology and anticancer drug response.

Saporin 6 and lonidamine in primary cell cultures from human breast carcinomas: a synergistic effect.

Lonidamine (LND) is a potential chemotherapeutic agent which can positively modulate the efficacy of several antineoplastic agents. The ribosome-inactivating protein Saporin 6 (SO 6), which acts as a rRNA N-glycosidase and a DNA nuclease, has recently attracted interest as a novel potential anticancer and antiviral agent. Synergism between LND and SO 6 was previously demonstrated by us in the human metastatic MAST breast cancer cell line in vitro. In the present study, the antiproliferative effect of the drugs, either alone or in combination, was investigated in vitro at various concentrations in 17 primary cell cultures established from patients carrying infiltrating ductal carcinomas of the breast. Results indicate a strong synergistic effect in 11/17 cases, when LND was administered as a second drug. This is in agreement with previous results in the MAST cell line. Synergism was evident at SO 6 concentrations between 3.3 x 10(-10) and 1.7 x 10(-9) M.

DNA-nuclease activity of the single-chain ribosome-inactivating proteins dianthin 30, saporin 6 and gelonin.

The single-chain ribosome-inactivating proteins (scRIPs) from plant origin are antiviral and antiproliferative agents employed in the preparation of immunotoxins. Similarly to the A-chains of ricin, sc-RIPs act as rRNA N-glycosidases. We demonstrate here that dianthin 30, saporin 6 and gelonin exert a specific nuclease activity on supercoiled DNA. Four specific sites of cleavage introduced by dianthin 30 and by saporin 6 and two specific sites of cleavage introduced by gelonin have been identified and mapped in pBR322.

A new cell line from human infiltrating ductal carcinoma of the breast: establishment and characterization.

We established a novel cancer cell line (MAST) from the ascitic fluid of a metastatic infiltrating ductal carcinoma of the breast. The epithelial and neoplastic nature of the MAST cells was confirmed by ultrastructural analysis. The cell line was maintained as a monolayer with a doubling time of about 68 h, and it possessed an abnormal karyotype with a modal chromosome number of 60, a trisomy of chromosome 18 and other unidentified rearranged chromosomes. Among the markers consistently found in MAST metaphases, we noted a t(14; 14) and a very large subtelocentric, a large satellited acrocentric and a very large submetacentric chromosome with striking fluorescent bands. Immunoenzymatic assay demonstrated that the MAST cell line was positive for estrogen and progesterone receptors. The in vitro drug-sensitivity assay showed a marked resistance of the cell line to 5-fluorouracil and 4-hydroperoxycyclophosphamide and a moderate resistance to etoposide and 4'-epidoxorubicin. The molecular analysis showed a four-to sixfold amplification of the c-myc gene and no amplification or rearrangement of the int-2, c-erbB-2, c-Ha-ras, c-mos and hst-1 genes.

In vitro potentiation by lonidamine of the sc-RIP saporin 6 effect in a human metastatic breast cancer cell line.

The ability of Lonidamine (LND), an energolytic derivative of indazole-carboxylic acid, to modulate the antiproliferative effect of the single-chain ribosome-inactivating protein Saporin 6 (SO 6) was investigated in the human MAST breast cancer cell line, recently established from an ascitic effusion of a ductal carcinoma, by analysis of protein synthesis inhibition and of colony formation in vitro. Different schedules were tested varying with regard to time of exposure (0-24 h), concentration of the drugs (0.01- > 10 micrograms/ml SO 6; 25-100 micrograms/ml LND) and sequence of administration (LND- > SO 6; SO 6- > LND; SO 6+LND). Results indicate that the marginal activity exerted here by each drug when tested independently is highly potentiated by the combination treatments, the cytotoxicity becoming significantly greater than that expected from an additive effect between the two drugs. In particular, a strong synergistic effect is obtained when SO 6 preceedes LND, with a reduction of the SO 6 IC 50 from 1.3 x 10(-7) M to 2.6 x 10(-9) M.

In vitro activity of taxol and taxotere in comparison with doxorubicin and cisplatin on primary cell cultures of human breast cancers.

The in vitro activities of taxol and taxotere in comparison with cisplatin and doxorubicin were assessed in 30 primary tumor cultures from human breast cancers. Both taxanes were much more potent than cisplatin and doxorubicin. Taxotere was 3.1; 296, and 9.6-fold more cytotoxic than taxol, cisplatin, and doxorubicin respectively. The cytotoxic activity observed in our experiments confirms the potential clinical relevance of the two taxanes in the management of breast cancer.

Diverse activity of sc-RIP saporin 6 on primary and metastatic melanoma cells in vitro.

The inhibitory effect of saporin 6, a single-chain ribosome-inactivating protein (sc-RIP) purified from the seeds of Saponaria officinalis, on the proliferation of human primary (MeWo, WM 164, SK MEL 28, MEM), cloned (MEM A9, A12, A13) and metastatic (M14) melanoma cells has been tested by protein synthesis and colony formation assays in vitro. Results indicate a marked difference in the sensitivity of primary and metastatic cells to the action of saporin 6, the latter being significantly more affected, both in treated and in pretreated cultures, with a high and specific response evident after 24 h of treatment and progressively increasing up to 72 h of culture with the drug (IC50 = 0.82 microgram/ml). This effect, which was dose-dependent in exponentially growing cells, was partially reversed upon removal of the inhibitor from the culture medium. No inhibitory effect was evident in the MeWo primary cells at the highest saporin 6 concentration used: the p170 glycoprotein-mediated mechanism is not involved in such a resistance pathway.

Inhibition of growth of breast cancer cells in vitro by the ribosome-inactivating protein saporin 6.

The antiproliferative activity of Saporin 6, a Ribosome-inactivating protein purified from the seeds of Saponaria officinalis has been tested on human breast cancer cells in vitro by the analysis (a) of colony formation in cells from surgical specimens from 27 patients bearing primary breast cancer and (b) of protein synthesis inhibition in the MCF/7 cell line. Results indicate a very high sensitivity of breast cancer cells from most patients to a short-term treatment with Saporin 6 at concentrations (10(-9) M), until now found effective only in acellular systems or after conjugation with monoclonal antibodies. On the contrary, the treatment of the human cell line MCF/7 indicate a very reduced sensitivity compared to fresh human neoplastic cells, with the necessity of a long lag for the effect to begin.

Effect of tulipin on cell cycle progression analyzed by BrdUrd incorporation.

The effect of tulipin, a protein from plant origin recently purified, on cell cycle progression has been analyzed in the sensitive EUE cells by BrdUrd incorporation. The cytofluorimetric results demonstrate that tulipin specifically interacts with the S phase, with a dose-dependent decrease of the total S phase cells and an increase of the G1/G2 cells after 4 h of treatment in the synchronized EUE cells, whereas in the asynchronous population it mainly causes a dose-dependent decrease in the incorporation of BrdUrd per cell.

Differential activity of saporin 6 on normal and leukemic hemopoietic cells.

The antiproliferative effect of saporin 6 (SO6), a ribosome-inactivating protein (RIP) purified from the seeds of Saponaria officinalis has been tested on three leukemic cell lines (K562, U937, and HL60), human normal bone marrow, and peripheral blood hemopoietic progenitor cells from normal subjects. In leukemic cell lines, SO6 appeared much more effective against erythrocytic than against monocytic and promyelocytic leukemic cells, as shown by protein synthesis assays carried out after up to 72 h of culture. Among the normal hemopoietic progenitor cells, erythroid burst-forming units were the most affected, with results similar to those observed in the erythroid leukemic cell line, both in treated and in pretreated cultures, with strong damage after 24 h of exposure to SO6. On the other hand, granulocyte-macrophage colony-forming units (CFU-GM) from bone marrow were significantly more affected than the myeloid leukemic cell lines after permanent treatment with the inhibitor, the damage being significantly lower after an exposure of 24 h. CFU-GM from peripheral blood and megakaryocyte CFU showed an intermediate sensitivity after 24 h of exposure to SO6, similar to that of the other normal precursors after permanent treatment with the drug.

Toxic and DNA-damaging activities of the fungicides mancozeb and thiram (TMTD) on human lymphocytes in vitro.

The cytotoxic and mutagenic effects of the fungicides mancozeb and thiram were studied using human peripheral blood lymphocytes cultured in vitro with or without an S-9 mix microsomal metabolizing system. The results obtained suggested that the chemicals caused dose-dependent inhibition of thymidine uptake and unscheduled DNA synthesis on both resting and proliferating lymphocytes in the absence of the S-9 mix. In the presence of the S-9 mix, only thiram showed mutagenic activity by eliciting unscheduled DNA synthesis and a significantly higher frequency of sister chromatid exchanges than did controls.

Purification, characterization and biological activity of tulipin, a novel inhibitor of DNA synthesis of plant origin.

A DNA synthesis-inhibiting protein (for which the term tulipin is proposed) was isolated from the bulbs of Tulipa sp. The yield ranged from 3.4 to 4.1 per cent of total protein content of the crude extract. Mr, isoelectric point, neutral and amino sugar and amino acid composition were determined. Inhibition of DNA synthesis varied in intact cells according to the cellular types studied, with a minimum ID 50% (concentration giving 50% inhibition) of 400 ng/ml in neuroblastoma cells. The effect was reversible. No effect was obtained in cell-lysate. RNA and protein synthesis were unaffected. The acute toxicity, evaluated in Swiss mice, gave an LD of 6.1 mg/kg body wt. Results of electron microscopy are also given. A second protein, called tulipin 2, has been isolated and partially characterized.

On the distribution of ribosome-inactivating proteins amongst plants.

The extracts from various parts (mostly seeds) of 56 different plants were examined for inhibition of protein synthesis by a rabbit reticulocyte lysate. Most extracts inhibited protein synthesis with an ID50 (concentration giving 50% inhibition) of 100 micrograms extract protein per ml, or less. The extracts with high activity were partially purified by CM cellulose chromatography. Protein-containing fractions were separated which inhibited protein synthesis and resembled the ribosome-inactivating proteins from plants previously described. Thus, ribosome-inactivating proteins appear to be virtually ubiquitous in plants.

Ribosome-inactivating proteins from the seeds of Saponaria officinalis L. (soapwort), of Agrostemma githago L. (corn cockle) and of Asparagus officinalis L. (asparagus), and from the latex of Hura crepitans L. (sandbox tree).

Ribosome-inactivating proteins, similar to those already known [Barbieri & Stirpe (1982) Cancer Surveys 1, 489-520] were purified from the seeds of Saponaria officinalis (two proteins), of Agrostemma githago (three proteins), and of Asparagus officinalis (three proteins), and from the latex of Hura crepitans (one protein). The yield ranged from 8 to 400 mg/100 g of starting material. All proteins have an Mr of approx. 30000 and an alkaline isoelectric point. Their sugar content varies from 0 (proteins from S. officinalis) to 40% (protein from H. crepitans). The ribosome-inactivating proteins inhibit protein synthesis by rabbit reticulocyte lysate, the ID50 (concentration giving 50% inhibition) ranging from 1 ng/ml (a protein from S. officinalis) to 18 ng/ml (a protein from A. githago). Those which were tested (the proteins from S. officinalis and from A. githago) also inhibit polymerization of phenylalanine by isolated ribosomes, acting in an apparently catalytic manner. The protein from H. crepitans inhibited protein synthesis by HeLa cells, with an ID50 of 4 micrograms/ml, whereas the proteins from S. officinalis and from A. githago had an ID50 of more than 50-100 micrograms/ml. The ribosome-inactivating proteins from S. officinalis and from A. githago reduced the number of local lesions by tobacco-mosaic virus in the leaves of Nicotiana glutinosa.

Properties of the ribosome-inactivating proteins gelonin, Momordica charantia inhibitor, and dianthins.

The amino acid and sugar compositions of four ribosome-inactivating proteins (gelonin, Momordica charantia inhibitor, dianthin 30 and dianthin 32) were determined. The proteins are all basic glycoproteins (pI greater than 8) containing mannose (more abundant in gelonin), glucose, xylose, fucose (absent from gelonin) and glucosamine. The ribosome-inactivating properties of the proteins examined are not modified by pretreatment with N-ethylmaleimide. Precipitating and inactivating antibodies can be raised against ribosome-inactivating proteins; a weak cross-reaction was observed only between dianthin 30 and dianthin 32.