Cytocompatibility of a matrix of methylated cassava starch and chitosan

Starches can be used to form edible or biodegradable films, and recently modified starches have been used to form self-supporting films by casting from aqueous solution. In this work, we aimed to propose a novel starch-based composite biomaterial matrix for use in biomedical applications, especially tissue engineering. The goal of the study was to evaluate the cytocompatibility of composite hydrogels of methylated starch and chitosan, using glutaraldehyde as the cross-linker. Commercial cassava starch with high purity (96.69%) was methylated with dimethyl sulfate in order to obtain a rigid material that could possibly render stronger mechanical properties to chitosan hydrogels. Therefore, methylated starch was mixed with a solution of chitosan and the cross-linking was induced by the addition of glutaraldehyde, allowing the formation of hydrogel films which were visualized under scanning electron microscopy. The method of fabrication was optimized based on the capacity of the cells to attach to the material and proliferate. After thorough washes with ethanol and saline solution, human fibroblasts were seeded on top of the gels and allowed to grow for 3 to 5 days. Cell viability was measured using an (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) MMT assay, and cell morphology was visualized by light microscopy. It was found that cells were viable at every time point, with their metabolic activity comparable to the controls (tissue culture plastic and chitosan alone), as well as clear cell–matrix interactions. Moreover, an increase in the metabolic activity over time indicated the capacity of the material to support cell proliferation. The proposed methylated starch–chitosan system is an excellent matrix that allows cell adhesion and could thereby be further assessed as a scaffold for tissue engineering.

Mucinous differentiation features associated with hormonal escape in a human prostate cancer xenograft

Many theories mention hypersensitive, promiscuous, outlaw or bypass signalling pathways to explain the acquisition of hormone independence in prostate cancer. Hormonal escape of prostate tumours is marked by many biological changes, including mucinous and neuroendocrine differentiation. Since expression of several mucins has been linked to carcinoma tumour progression, we have characterised the expression of mucins at both RNA and protein levels in an in vivo model of prostate cancer in hormonal escape. Using PAC120, a xenograft of a human hormone-dependent prostate tumour, and its hormone-independent variants, we analysed the expression of mucins (MUC1, MUC2, MUC4, MUC5AC, MUC5B, MUC6) by immunohistochemistry or reverse transcriptase (RT)-PCR. While the parental PAC120 tumour was a compact poorly-differentiated tumour of Gleason score 9 (5+4), hormone-independent variants displayed mucinous, neuroendocrine-like or mixed histological changes; these changes were stable through serial transplantations or after testosterone supply. MUC1 mRNA was expressed in both PAC120 and the hormone-independent variants, although at variable levels. All tumours displayed a high and constant expression of MUC2 and no expression of MUC4 mRNA. While MUC1 was expressed in all xenografts whatever their hormone dependence status, MUC2, MUC5B and MUC6 were preferentially expressed in hormone-independent variants. The loss of hormone dependence in this prostate cancer xenograft model is therefore marked by irreversible histological alterations, mucinous or neuro-endocrine, associated with an expression of secretory MUC2, MUC5B and MUC6, independent of the histological differentiation subtype. These data point to mucinous differentiation as an important step in the acquisition of hormone independence in this cancer, and suggest that secretory mucins might participate in an unknown pathway of hormonal escape in prostate cancer.

[A new model of human prostate cancer, the PAC120 xenograft]

Prostate cancer is the second cause of cancer death in men. Often, initialy hormono-independent, escape from anti-androgen therapy is a key event of tumoral progression showing an hormone-independent phenotype. To study morphological, genetic and molecular bases associated with the hormono-dependence escape, a new model of human adenocarcinoma prostate xenograft, PAC120, was established with its hormono-dependent and independent variants. Its growth was strongly inhibited by surgical castration or by administration of the new gonadotrophin-releasing hormone antagonist, FE 200486 (Ferring, San Diego, CA). Evolution to hormono-independence was frequently associated with a mucoid differentiation or a neuroendocrine-like pattern, with the apparition of new chromosomic alterations and variations of human gene expressions. PAC120 xenograft is a new model of hormone-dependent prostate cancer, opening the opportunity to study the hormone dependence escape mechanism and to evaluate the efficacity of new therapeutics.

[Molecular and cell aspects of the cancer metastasis]

The metastasis dissemination is a process which leads to a primary tumor cells to migrate, infiltrate host tissues and form a secondary tumor focus at distance. This clinic evolution is a consequence of the cancer natural history and is due to the appearance of new potentialities in tumoral cells, providing to a small quantity of them an invasive and metastatic capability. This dissemination is possible by many factors; among them the lack of cohesion in tumor tissue cells, forming new blood vessels, resistance to anoikis and posterior implantation of tumoral cells in a heterotypic site. The change of cohesion in cell systems, synthesis of proteolytic enzymes, cell motility, modification of signals induced by growth factors, or the substratum for environment adhesion, and lack immune recognition by the immunologic system, are the main contributors to the appearance of metastasis. A permissive ecosystem is necessary to implant tumoral cells in target organs such as: liver, lung and bone marrow. This special environment, which is more favorable to metastasis, supplies an stroma, adhesive systems, growth factors and neo-vascularization. It is important to point out that the development of a metastasis is preceded by some genetic changes which make possible the adaptation of malign cells to a new microenvironment.

Analysis of the distribution pattern of sister chromatid exchanges in mitotic chromosomes of human T-lymphocytes

Band locations of 344 sister chromatid exchanges (SCE), observed in chromosome preparations of peripheral T-lymphocyte cultures, were identified using a sequential Q-banding-sister chromatid differentiation staining protocol. A comparison between expected Poisson, expected negative binomial distributions and observed SCE patterns, revealed that the negative binomial distribution provided a better fit to our SCE data. The aggregated pattern of SCE distribution indicated that some bands were more prone to undergo these events. Genetic markers assigned to those bands recording a significant number of exchanges seemed to correspond with the transcriptionally active genes. The results confirm that SCE are induced at the early S-phase of the cell cycle involving the early replicating genes in these events. Potential applications of cytogenetic techniques employed in the present study are proposed.

[Pharmacological biomodulation in cancer]

The discovery of the P-glycoprotein as a mediator of multidrug resistance (MDR) represents one of the most important research accomplishments in antineoplastic pharmacology during the last decade. Demonstration of Pgp in epithelial tissues, untreated and chemotherapeutically pretreated human malignancies, and identification of various agents capable of reversing in vitro resistance has generated enthusiasm for clinical studies throughout the world. This review discusses recent developments of experimental and clinical investigations of MDR reversing agents in cancer.

Synergistic efficacy of 3n-butyrate and 5-fluorouracil in human colorectal cancer xenografts via modulation of DNA synthesis

BACKGROUND & AIMS

Butyrate, produced in the colon lumen, maintains mucosal cell homeostasis. Poorly diffusible, its access is compromised in growing colon cancers and absent in distant metastases. Butyrate regulates DNA synthesis. We postulated that systemic administration of butyrate should reduce colon cancer growth and enhance 5-fluorouracil (5-FU) efficacy.

METHODS

A stable derivative of butyrate (3n-But) was used. The antitumoral efficacy of 5-FU and 3n-But, alone or combined, was evaluated in human colorectal cancers (hCRCs) subcutaneously, orthotopically, or intrasplenically grafted into nude mice. Thymidylate synthase (TS) and thymidine kinase (TK) mRNA expression, proliferation, apoptosis, and cell cycle alterations were studied.

RESULTS

In vivo, 5-FU alone inhibited growth of only 3 of the 12 hCRCs tested and 3n-But alone had no effect; the 5-FU/3n-But combination inhibited growth of all 16 hCRCs tested. The hCRCs differed in their p53 and microsatellite instability status. 5-FU/3n-But decreased TK and TS mRNA expression by 20- and 40-fold, respectively, and TS activity by 75%, stopped cell proliferation without affecting cell differentiation, and significantly enhanced apoptosis. 3n-But potentiated the efficacy of Tomudex and methotrexate, 2 TS inhibitors, but not that of oxaliplatin. In vitro, 5-FU/3n-But inhibited [3H]thymidine but not bromodeoxyuridine incorporation and induced apoptosis in hCRC cell lines. Cells treated with 5-FU/3n-But did not accumulate in G1 nor in S phase of the cell cycle, while 5-FU and 3n-But arrested the cycle in S and in G1 phase, respectively. 3n-But prevented the cell rescue from 5-FU-induced cytotoxicity by uridine or thymidine.

CONCLUSIONS

3n-But and TS inhibitors acted synergistically against colorectal cancers, independently of the genetic alterations of the hCRCs. The mechanism of action of 5-FU/3n-But could be enhanced reduction of TS and prevention of thymidine salvage in DNA synthesis.

[Multidrug or pleiotropic resistance]

The resistance to cytotoxic drugs represents a major obstacle to successful cancer therapy. The intrinsic resistance of tumoral cells is one of major causes of treatment failure. The overexpression of a membrane associated glycoprotein, P-glycoprotein, in tumoral cell lines, resistant to a wide range of drugs, permitted the description of a multidrug resistance (MDR) phenotype. This P-glycoprotein, which appears to play a role in drug efflux is encoded by the mdr1 gene in humans. The frequent mdr1 gene overexpression in clinically resistant tumours suggest that this gene may be the cause of treatment failure in human cancer. This review summarizes recent developments in this area, which suggest that both the activity of the pump and its genetic regulation are potential targets for new anticancer therapies.

Structural modification of berberine alkaloids in relation to cytotoxic activity in vitro

The cytotoxicity of two protoberberine alkaloids: berberine and lincangenine, their 8-hydroxy-7,8-dihydro-derivatives and tetrahydroprotoberberine:thaicanine, was evaluated. The cellular responses through the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] (MTT) method were measured in Hela (uterus carcinoma), SVKO3 (ovary carcinoma), Hep-2 (larynx carcinoma), primary culture from mouse embryon, and human fibroblast cells at the concentration: 10-1000 ppm (microg/ml) for 24 h. Berberine showed the highest cytotoxicity among the compounds tested, giving LC50 values for all cell lines at the concentration of 10 ppm. The results indicated that the cytotoxicity was notably decreased by structural changes, i.e. by modulation of the planarity caused by the introduction of hydroxyl group at C-8 and concomitant saturation of double bond between N-C8 in protoberberine molecules. In the case of berberine, the cytotoxic effect changed from 98.8 (berberine) to 39% for 8-hydroxydihydroberberine at the concentration of 100 ppm in Hela cells line. The same effect was observed with lincangenine and 8-OH-lincangenine (cytotoxicities 70 and 25%, respectively, at 1000 ppm in SVKO3 cells). On the other hand, these compounds showed a low selectivity for the different human cancer cell lines tested.

Distinctive potentiating effects of cisplatin and/or ifosfamide combined with etoposide in human small cell lung carcinoma xenografts

Combined modalities are currently used for cancer therapy, although their mechanisms of activity remain incompletely deciphered. The design of new drug combinations suffers from our inability to anticipate accurately their efficacy or toxicity. They can be evaluated in vivo, using human tumors grafted into immunodeficient mice, as we did here with combined protocols used in the clinical setting. Xenografts of small cell lung carcinoma (SCLC) from eight patients were used to test the tumor sensitivity to etoposide (VP16; 12-16 mg/kg/days, days 1, 2, and 3), cisplatin (CDDP; 6-9 mg/kg/day, day 1) and ifosfamide (IFO; 90-210 mg/kg/day, days 1, 2, and 3) as single agents and to evaluate the efficacy of the two-drug or three-drug combinations. Five xenografts came from untreated patients (SCLC-61, SCLC-6, SCLC-10, SCLC-41, and SCLC-96) and three after treatment (SCLC-74, SCLC-101, and SCLC-108). p53 was inactivated in all of them. Tumor growth inhibition, growth delay, and the survival rate of tumor-bearing mice reflected individual SCLC chemosensitivity. As single agents, IFO inhibited tumor growth in a dose-dependent manner, whereas CDDP and VP16 had little or no effect. Both CDDP and IFO potentiated VP16, inducing complete regressions in the most sensitive SCLCs; VP16-IFO was more effective than VP16-CDDP, with complete regressions in six versus three of the eight tumors tested, respectively. CDDP-IFO was less effective than VP16-IFO, with three of eight SCLCs giving complete regressions. The three-drug combination led to modest improvement over the best two-drug combination but only for sensitive SCLCs. Because drug-responses distinguished two classes of SCLCs, as sensitive or refractory, MDR1, glutathione S-transferase pi, lung-related multidrug resistance protein, multidrug resistance protein, and topoisomerase IIalpha mRNA expression was studied by semiquantitative reverse transcription. There was no correlation with SCLC sensitivity; topoisomerase IIalpha and multidrug resistance protein was expressed in all cases, lung-related multidrug resistance protein and glutathione S-transferase pie in seven of eight, and MDR1 gene in four of eight. In conclusion, these SCLC xenografts displayed a pattern of chemotherapy response close to that observed in patients. This model confirmed that in two-drug combinations, each component potentiated the effects of the other, with VP16-IFO tending to be the best two-drug combination, both of which were more effective than VP16-CDDP and better tolerated than CDDP-IFO. The addition of a third agent gave a modest, if any, therapeutic benefit in the responders but none in refractory SCLCs. There was no correlation between the extent of response and resistance markers.

11-Deoxyfistularin-3, a new cytotoxic metabolite from the caribbean sponge Aplysina fistularis insularis

11-Deoxyfistularin-3 (1), a new bromotyrosine derivative, was isolated among other known compounds such as fistularin-3 (2), aerothionin (3), and 11-oxoaerothionin (4) from the Caribbean sponge Aplysinafistularis (Aplysinellidae). The structure of 1 was determined by spectroscopic analysis and showed in vitro activity against the human breast carcinoma cell line MCF-7.

Multidrug resistance genes (MRP) and MDR1 expression in small cell lung cancer xenografts: relationship with response to chemotherapy

Intrinsic or acquired drug resistance is a major limiting factor of the effectiveness of chemotherapy. Increased expression of either the MRP gene or the MDR1 gene has been demonstrated to confer drug resistance in vitro. In this study, we examined MRP and MDR1 gene expression in a panel of 17 small cell lung cancers (SCLC) xenografted into nude mice from treated and untreated patients using an RT-PCR technique. For some of them, the outcome of the corresponding patients was known and we related MDR1/MRP expression with the xenograft response to C'CAV (cyclophosphamide, cisplatin, adriamycin and etoposide) combined chemotherapy. Fifteen (88%) of the 17 cases of SCLC were found to be positive for either MDR1 or MRP. MRP gene expression was present in 12 (71%) of 17 cases, whereas MDR1 gene expression was detected in eight (50%) of 16 cases. For six SCLC, the survival duration of patients differed, with three patients surviving for more than 30 months after therapy. Among these six turnours, five expressed MRP and/or MDR1. These six xenografts responded to the C'CAV treatment but a significant rate of cure was obtained in only three cases. No obvious relationship was observed between the response to this treatment and MRP or MDR1 expression. However, the remarkably high levels and frequency of MRP expression in some SCLC samples indicate that future developments in chemotherapy of this tumour type should anticipate that drugs which are substrates of MRP may be of limited effectiveness.

High glycolysis in gliomas despite low hexokinase transcription and activity correlated to chromosome 10 loss

Loss of chromosome 10 was observed in 10 out of 12 xenografted glioblastomas studied. Chromosome 10 carries the gene coding the hexokinase type 1 isoenzyme (HK-I), which catalyses the first step of glycolysis, which is essential in brain tissue and glioblastomas. We investigated the relationships between the relative chromosome 10 number, the amount of HK-I mRNA, HK-I activity and its intracellular distribution, and glycolysis-related parameters such as the lactate-pyruvate ratio, lactate dehydrogenase (LDH) and ATP contents. Individual tumour HK-I mRNA amounts were 23-65% lower than that of normal human brain and reflected the relative decrease of chromosome 10 number (alpha < 0.01). Total HK activities of individual glioblastomas varied considerably but were constantly (a mean of seven times) lower than that of normal brain tissue. The mitochondria-bound HK-I fraction of individual tumours was generally over 50%, compared with that of normal brain tissue. As shown by lactate - pyruvate ratios, in all the gliomas, glycolysis was elevated to an average of 3-fold that measured in normal brain. An elevated ATP content was also constantly noted. Adaptation of glioblastoma metabolism to the chromosome 10 loss and to the HK-I transcription unit emphasises the critical role of glycolysis in their survival. We hypothesise that HK-I, the enzyme responsible for initiating glycolysis necessary for brain function, may approach its lowest limit in gliomas, thereby opening therapeutic access to pharmacological anti-metabolites affecting energy metabolism and tumour growth.

HLA class I and neuroendocrine antigen expression in multidrug resistant small cell lung carcinoma cell lines

Antigenic marker expression was studied in a series of eight small cell lung carcinoma (SCLC) cell lines, according to their histological subtype, classic or variant. These lines were obtained from human tumors xenografted into nude mice, originally derived from heterotransplanted tumor biopsy samples. We looked at an altered expression of HLA class I antigens, a battery of neuroendocrine antigens and the P-glycoprotein (Pgp) responsible for MDR1 encoded multidrug resistance, as markers of tumor malignancy. Three cell lines out of four of the classic subtype and two cell lines out of four of the variant subtype showed a lack or a low expression of HLA class I antigen. Recombinant interferon gamma (rIFN-gamma) treatment (100 U/ml, for 48 h) increased HLA class I expression of the cell lines differently, but did not induce an imbalance between HLA-A and HLA-B molecules as described in other tumor models. Neuroendocrine antigens were tested in six out of these eight lines, using a family of monoclonal antibodies developed against the cell membrane antigens of low passage cell lines derived from pleural effusions (de Leij et al, Cancer Res 45: 2192-2200, 1985). Globally, these antigens were more highly expressed in classic subtypes of SCLC. Neuroendocrine antigens corresponding to MOC-21 and MOC-32 monoclonal antibodies were weakly expressed in variant forms. Pgp expression was detectable with the JSB1 monoclonal antibody on the three variant SCLCs out of the six lines. Comparing two cell lines originated from the same patient before and after therapy, we showed that neuroendocrine reactivity to MOC-21 and MOC-32 was lost simultaneously with a gain of Pgp expression, and with a classic to variant histological transition. With regard to the clinical evolution, HLA class I expression and stimulation by rIFN-gamma was not related to malignancy. It appears that for variant forms, a low expression of neuroendocrine antigens detected by MOC-21 and MOC-32 monoclonal antibodies and a high level of Pgp predict for a poor prognosis.

Adding a reverser (verapamil) to combined chemotherapy overrides resistance in small cell lung cancer xenografts

Small cell lung carcinomas (SCLC) are characterised by chemosensitivity to diverse antitumoral compounds. However, responses are transitory and relapses are commonly observed. We examined the ability of verapamil, a reverser of P-glycoprotein (Pgp)-related resistance, to improve the efficacy of CyCAV combined chemotherapy (Cy, cyclophosphamide (CPA); C, cisplatin (CDDP); A, doxorubicin (ADM);V, etoposide (VP16)), as currently administered to SCLC patients at Institut Gustave-Roussy, France, and adapted to the treatment of nude mice implanted with these tumours. Although Pgp encoded by the MDR1 (multidrug resistance) gene is not the only mechanism for multidrug resistance (MDR), and not all drugs included in this regimen are recognised by Pgp, we anticipated a therapeutic benefit. Four different SCLC lines, expressing the MDR1 gene and recently grafted into nude mice, were used. SCLC-75, SCLC-6 and SCLC-41 originated from untreated patients, and SCLC-74T was derived from a patient treated with a combination of ADM, CPA and VP16. SCLC-41% and SCLC-6T tumours were used after having undergone, respectively, five and nine cycles of in vivo passage and CyCAV treatment of the tumour-bearing nude mice, to reinforce their chemoresistance. The efficacy of the CyCAV regimen, associated with or without verapamil (given 24 h before CyCAV on days 1-5), was tested on the growth of these SCLC. Verapamil (25 mg/kg) improved the antitumour effect of CyCAV in mice bearing SCLC-6T, SCLC-41T and SCLC-75 tumours, although toxicity was observed. Verapamil modestly delayed the plasma clearance of ADM. Two daily injections of 10 mg/kg of verapamil, administered at a 3 h interval, proved to be effective, whereas the same total dose administered as a bolus was not. These results indicate that the association of some reversers of MDR, including drugs possibly interacting with Pgp, might potentiate SCLC combined chemotherapy.

Evolution of chromosomal alterations and biologic features in two small cell lung carcinoma cell lines established from one patient during the course of the disease

Two small cell lung cancer (SCLC) cell lines were established from metastases of a patient during the course of the disease. SCLC 74A was derived from biopsy material obtained at the time of diagnosis and SCLC 74B was from a biopsy specimen of a relapsed tumor obtained after treatment. A transition occurred from SCLC 74A, an intermediate form with 5% large cells to SCLC 74B, a standard mixed form with 20% of large cells, with a decrease in neuroendocrine markers and a substantial increase in P-glycoprotein, a multidrug resistance marker. For both cell lines, R-banding and FISH indicated a del(1)(p35pter) also found in other neural-crest-derived tumors, the loss of regions with suspected tumor suppressor genes at 3p, 5q, and 17p, and a recurrent translocation of the 6q24-6qter region to 10p14. Further genetic modifications in SCLC 74B affected chromosomes 2, 3, 5, 10, 11, 14, and 15. The main observations were a der(2)t(2;5)(p16;q?); a der(3;11)(q10;p10) in SCLC 74A which became der(3;14)(q10;p10) and der(11;14)(p10;q10) in SCLC 74B; and the insertion of the 5q13-5q31 region in the der(10)t(6;10). The finding of the same structural abnormalities in both cell lines suggests a monoclonal origin for both metastases. Hypotetraploid cells were in the same proportion as large cells whose number was a characteristic feature of each cell line. They possessed twice the same chromosomal alterations observed in the hypodiploid cells. This suggests a permanent process of tetraploidization.

Establishment and characterization of five human small cell lung cancer cell lines from early tumor xenografts

Five small-cell lung carcinoma (SCLC) cell lines were established from xenografted tumor lines. These tumor lines were established after transplantation into nude mice of primary tumors or metastatic foci obtained surgically, from untreated (IRSC-2M, IRSC6M, IRSC-10M and IRSC-61M) or treated patients (IRSC-74M). They were then set-up in culture as parallel cell lines. Histologically, these tumor lines were classified as being of the classic (IRSC-2M, IRSC-10M and IRSC-61M) or intermediate type (IRSC-6M and IRSC74M). Four of these 5 SCLC cell lines grew as floating cell aggregates, while one (IRSC6M) grew as an adherent cell monolayer. Growth rates were slow (doubling times ranged between 120 and 194 h) but could be accelerated (67 to 144 h) by cultivating cells in medium mixed (v/v) with self-conditioned medium. Electron microscopical examination revealed that all SCLC cell lines contained dense core granules, characteristic of their neuroendocrine origin. These cell lines formed colonies in agarose with colony forming efficiencies ranging from 0.02-0.36%. The classic-type cell lines retained their tumorigenic capacity when re-injected intracranially into naive nude mice, whereas the intermediatetype cells did not. Cytogenetic analysis confirmed the human origin of SCLC xenografts and cultured cell lines. Various numerical and structural chromosome abnormalities were found, with deletion in the short arm of chromosome 3 being the most common (4 of the 5 cell lines). Deletions in or loss of the chromosome 10 were also observed. Oncogene expression was studied in 3 representative cell lines (IRSC-10M, IRSC-2M and IRSC-74M). L-myc was overexpressed only in IRSC-74M, while the GRP gene was overexpressed in the classic (IRSC-2M and IRSC-10M) but not in the intermediate-type cells (IRSC-74M). The Ki-ras oncogene was overexpressed in the 3 cell lines, while c-myc, N-myc, Ha-ras, N-ras, erb B2 and sis were not detected in any of them. The 3 cell lines weakly expressed the MDR1 gene, while the GST-pi gene was not expressed. These cell lines constitute a multifaceted well-characterized in vitro model for studying the biology of these phenotypically diverse cancer cells.

HOX gene expression in human small-cell lung cancers xenografted into nude mice

Transcription factors are crucial to an understanding of the molecular basis of neoplasia. Homeobox-containing genes are a family of transcriptional regulators encoding DNA-binding homeodomains, involved in the control of normal development. Class-I human homeobox-containing genes (HOX genes) display a peculiar chromosomal organization, perhaps directly related to their function. Aberrant expression of homeobox-genes has been associated with both morphological abnormalities and oncogenesis. We have recently observed that alterations in HOX gene expression are detectable in kidney and colon cancer when compared to the corresponding normal organs. Here we have analyzed the expression of HOX genes in primary and metastatic human small-cell lung cancer (SCLC) xenografted in nude mice, in order to investigate whether HOX gene expression correlates with the histology and stage of SCLC progression. The results show that different SCLCs display differential patterns of HOX gene expression. Furthermore, in SCLC, the number of actively expressed HOX genes might be substantially lower in metastatic cancers than in primary tumors. The alteration in HOX gene expression in SCLCs mainly concerns the HOX B and C loci. This finding suggests that downregulation of HOX genes may play a role in small-cell lung cancer progression, possibly through their implication in tumor suppression.

Response of small-cell lung cancer xenografts to chemotherapy: multidrug resistance and direct clinical correlates

BACKGROUND

Patients with small-cell lung carcinomas (SCLCs) initially respond to combination chemotherapy. Only a few benefit in terms of long-term survival because most relapse. Such outcome may be attributable to development of multidrug resistance.

PURPOSE

The response of SCLC to chemotherapy was examined in terms of (a) patient survival, (b) drug sensitivity of tumors in patients and of tumor xenografts in nude mice, and (c) expression of multidrug resistance gene MDR1 and GST-pi gene.

METHODS

Tumor samples obtained from seven untreated patients and from one patient both before and after chemotherapy were transplanted into nude mice. The patients were treated with a combination of cyclophosphamide (C'), cisplatin (C), doxorubicin (A), and etoposide (V) (C'CAV) or C'AV and radiotherapy. Drug sensitivity of SCLCs was tested in nude mice that had received tumor xenografts from these seven patients. The expression of MDR1 and GST-pi genes was assessed in the mRNA extracted from xenografts by Northern blot analysis. P-glycoprotein was quantified by enzyme immunoassay.

RESULTS

The patients' responses to C'CAV closely correlated with those of the corresponding xenografts. The tumors of the two patients who showed long-term survival after C'CAV completely regressed when they were transplanted into nude mice and subsequently treated with C'CAV. Despite initial complete response, the remaining five patients died during year 1. A high percentage of mice receiving the tumor grafts from these five patients showed only partial tumor regression after C'CAV treatment. The MDR1 transcript was detected in all five of these xenografts. Four of five xenografts were from untreated patients, and the fifth was from a treated patient. MDR1 mRNA expression was absent in the tumor of this fifth patient before chemotherapy, but both the mice receiving the corresponding xenograft and the patient showed expression of MDR1 after C'CAV treatment. MDR1 mRNA expression was absent in the tumor xenografts obtained from two patients with long-term survival. Expression of P-glycoprotein correlated with MDR1 mRNA expression. All xenografts except one expressed the GST-pi gene.

CONCLUSIONS

The absence of MDR1 gene expression during chemotherapy for SCLC indicates a favorable prognosis, gene expression is often coincident with ineffective chemotherapy, and tumor xenografts can be appropriately used to predict response to chemotherapy.

IMPLICATIONS

Failure of chemotherapy to control SCLC seems to be related to an acquired multidrug resistance involving the MDR1-mediated mechanism. Therapeutic benefit could therefore be expected from chemotherapy combined with inhibitors of MDR1.

Antitumor activity of the new vinca-alkaloid S 12363 alone or in combination with verapamil on a human multidrug resistant renal carcinoma xenograft

We have established a model of human renal cell carcinoma, Kgg2, transplanted into athymic nude mice which expressed P-glycoprotein (P-gp) (detected by flow cytometry) and a high level of mRNA transcript of mdr1 gene (Northern blot analysis). We have evaluated the antitumor activity of a new highly potent vinca-alkaloid derivative, S 12363, in comparison with the activity of the reference compound vinblastine (VLB), when used alone or in combination with verapamil (VRP). The influence of the calcium influx blocker verapamil on the activity of the combination of S 12363 with adriamycin (ADR) was also determined. The results showed that S 12363 at a dose of 0.05 mg/kg/day, administered alone by intraperitoneal route daily on days 1 to 5, induced a tumoral regression of 50% during the first days after treatment. This effect was potentialized by simultaneous treatment with verapamil at 20 mg/kg/day for 5 days, leading to a long-term reduction of 70% of tumor growth. Vinblastine at a dose of 0.4 mg/kg/day administered alone or in combination with verapamil, using the same protocol, was less efficient. The association of S 12363 at 0.075 mg/kg/day (on days: 1-5, 11, 21 and 31), adriamycin at 2 mg/kg/day (on days: 11, 21 and 31) and verapamil at 20 mg/kg/day (on days: 0-5, 11, 21 and 31) induced an important reduction of tumor growth of 80% at the end of the experiment. In conclusion, the new vinca-alkaloid derivative S 12363 could present a therapeutic advantage over the reference compound vinblastine in the treatment of renal cell carcinoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterogeneous expression of oncogenes in small-cell lung-cancer xenografts

The analysis of oncogene expression may provide insights into the pathogenesis of small cell lung cancer (SCLC) and may help to predict clinical behavior. The expression of 8 oncogenes (c-myc, N-myc, L-myc, Ha-ras, Ki-ras, N-ras, erbB-2, v-sis) was evaluated in small cell lung cancer (SCLC) xenografts of tumor samples, recentlly transplanted, taken from 17 different patients. Eight of these 17 SCLC lines expressed the L-myc oncogene and 2 SCLC lines expressed the c-myc oncogene. One SCLC line (SCLC-63M) simultaneously expressed the L-myc and c-myc oncogenes. All SCLC lines examined had almost similar high RNA levels of the Ki-ras oncogene, while the expression of Ha- and N-ras oncogenes was not always observed. The N-myc and v-sis oncogenes were expressed in only one tumor and at a very weak level, and no transcript of the erbB-2 oncogene was observed in any of our 17 SCLC lines. These results indicate that oncogene expression in SCLC lines is heterogeneous, with the exception of the Ki-ras oncogene which is constantly overexpressed.

Response of a multidrug-resistant human small-cell lung cancer xenograft to chemotherapy

Small-cell lung carcinomas (SCLC) are highly responsive to various chemotherapies. However only a minority of patients benefit from long survival. SCLC patients treated at the Institut Gustave Roussy received a combined chemotherapy (CCAV) including cisplatin, cyclophosphamide (Cpa), Adriamycin (doxorubicin; Adm) and vepeside (VP16). We report here the intrinsic sensitivity of a small-cell lung carcinoma, designated SCLC-6, grafted in nude mice. This xenografted tumour was derived from an untreated patient. The CCAV regimen given to the patient donor of the tumour sample resulted in a complete response followed by recurrence and death, 8 months after the initial cure. The expression of P-glycoprotein encoded by the MDR1 gene was detected with the C219 antibody on the membrane of SCLC-6 tumour cells. When given to SCLC-6-tumour-bearing nude mice, CCAV induced a strong inhibition of tumour growth (84% of growth inhibition, 20 days after start of the treatment), but no cure. Intensification of CCAV doses did not improve the response. The efficacy of individual agents of the CCAV, given at maximal tolerated doses was analysed. Only cisplatin (10 mg/kg) and Cpa (3 x 50 mg/kg) inhibited SCLC-6 growth (79% and 100% inhibition respectively), VP16 (3 x 24 mg/kg) was poorly efficient (42%) and Adm (10 mg/kg) not at all. Two-drug combinations such as cisplatin plus VP16 or cisplatin plus Cpa inhibited tumour growth (81% and 70%, respectively). Curiously, the efficacy of Cpa, given in combination with cisplatin was less than that of Cpa alone. Repeated treatments with CCAV administered to mice at each in vivo passage of the tumour induced a loss of chemosensitivity, which was observed until the ninth passage. An improvement of the therapeutic response was obtained by adding a headline reverser of multi-drug resistance, verapamil (25 mg/kg), to CCAV (81% versus 63% inhibition). MDR1-related resistance appeared to play a role in the failure of SCLC-6 chemotherapy; frequent recurrences after treatment with cisplatin and Cpa, two drugs that are not recognized by the P-glycoprotein, indicated that other modes of resistance were simultaneously active.

Antitumoral activity of bombesin analogues on small cell lung cancer xenografts: relationship with bombesin receptor expression

Gastrin releasing peptide (GRP), the human homologue of bombesin (BN), is an autocrine growth factor for small cell lung cancer (SCLC) cells. The synthetic octapeptides [D-cpa1-beta-Leu8-des-Met9]litorin (BIM 26182) and [D-Phe6-Leu13-CH2NH-Cpa14]bombesin(6-14)NH2 (BIM 26189) are potent GRP/BN antagonists of the proliferation of 3T3 and rat pancreas cells. The effect of these analogues on the proliferation of four SCLC cell lines (SCLC 6, SCLC 41, SCLC 75, SCLC 74R) was tested in vitro and in vivo. Two of these SCLC lines (SCLC 41M and SCLC 75) had receptors for BN/GRP and expressed the prepro-GRP mRNA. BIM 26182 and BIM 26189 inhibited [3H]thymidine incorporation into the DNA of SCLC 41 cells, stimulated [3H]thymidine incorporation in SCLC 6, and had no effect on the two other cell lines. The SCLC implanted s.c. in nude mice were treated with either BIM 26182 or BIM 26189. BIM 26182 and BIM 26189 injected at the doses of 50 micrograms twice a day (s.c.) around the tumor for 10 to 21 days delayed the growth of SCLC 41 and of SCLC 75. The maximal effect was observed during the treatment period, after which the tumors regrew, suggesting a cytostatic effect of these peptides. No inhibitory effect of the peptides on SCLC 74R or SCLC 6 growth was observed. These data suggest that GRP antagonists are able to inhibit the in vitro and in vivo growth of BN/GRP receptors-positive SCLC.

Efficient malignant transformation of rat embryo fibroblasts by genomic DNA from Walker carcinoma cells

DNA isolated from Walker carcinoma ascites cells was transfected into primary rat embryo fibroblasts (REF), selecting transformed cells by growth in soft agar after prolonged propagation in monolayer. Both high molecular weight genomic DNA and a partially purified mitochondrial DNA fraction were able to transform REF with high efficiency, whereas pure mitochondrial DNA failed to elicit a transformed phenotype. Hybridization experiments showed that the mitochondrial DNA fraction contained DNA species of presumably extramitochondrial origin. Colonies were cloned into morphologically transformed, foci-forming, immortalized cell lines, showing different degrees of chromosomal alterations, tumorigenicity, and production of cell growth factors. These results indicate that although REF are refractory to genomic neoplastic DNA or to single cloned oncogenes in the absence of enhancers, they can be efficiently transformed by chromosomal DNA from a highly malignant tumor under conditions selecting against the remaining normal cells.

Establishment and characterization of cell lines from the Walker carcinoma 256 able to grow in suspension culture and deficient in thymidine kinase

A cell line from the Walker carcinosarcoma 256 of the rat has been established in suspension culture in medium with 5% bovine calf serum for over 350 generations, with an average population doubling time of 17 h, a plating efficiency of 56%, a colony forming efficiency of 32%, and a good capacity to form colonies in soft agar. The cells are morphologically indistinguishable from those in the solid tumor and ascites as checked by transmission and scanning electron microscopy. The karyotype is characterized by a modal number of 65 chromosomes and by the presence of a marker metacentric chromosome. The cells express thymidine kinase, gamma-glutamyl transpeptidase, and alkaline phosphatase; are agglutinable by concanavalin A; and can be synchronized by the triple thymidine block. They induce primary tumors, both subcutaneously (solid) and intraperitoneally (ascitic), in the rat; are able to metastasize upon injection by the tail vein; and invade the chorioallantoic membrane of the chick embryo. Cells in suspension can be transferred to monolayers, considerably decreasing their tumorigenicity without affecting the other parameters studied, and can be switched back to suspension culture. DNA-mediated transfection showed that DNA from these cells can transform the NIH-3T3 line. Upon growth of the monolayers in a BrdUr-containing medium, a sub-line was established that was cloned into a thymidine kinase-deficient line unable to grow in HAT medium and with properties otherwise similar to those of the parental wild type cells.