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J P Bergerat

Publications and source records attributed to J P Bergerat.

At least 19 recordsLinked to original sources
PubMed2005

Cisplatin-induced genes as potential markers for thyroid cancer.

Despite the uncontested role of p53 in cycle arrest/cell death after cisplatin treatment, to date the question whether wild-type p53 confers a resistant or sensitive status on the cell is still a matter of debate. Isogenic and isophenotypic human thyroid papillary carcinoma cell line variants for p53 differently expressed cycle genes after cisplatin treatment. Seven genes (CDC6-related protein, CCNC, GAS1, TFDP2, MAPK10/JNK3, WEE1, RPA1) selected after expression on an Atlas human cell cycle array were analyzed by quantitative real-time PCR. While cisplatin treatment increased their expression in p53 wild-type cells it decreased it in cells with inactivated p53 and had no or less effect on cells with mutated p53. These results show that in a well-defined system, different alterations of p53 can lead to a different regulation of genes and hence to either resistance or sensitivity to cisplatin. Moreover for the first time, MAPK10/JNK3 was identified in human thyroid cells and tissue. Four of the genes (CDC6-related protein, CCNC, GAS1 and TFDP2) were decreased in human papillary carcinoma tissues. Relevance of these genes (especially a decrease in GAS1 in thyroid papillary carcinoma) in various malignant pathologies has already been shown. These genes may be explored as new markers in advanced thyroid cancer such as metastatic and anaplastic forms displaying p53 alterations.

Antineoplastic Agents↗
PubMed2004

Cisplatin enhances the cytotoxicity of fast neutrons in a murine lymphoma cell line.

The utilization of high linear energy transfer (LET) radiations, such as fast neutrons or carbon ions (hadrontherapy), offers promising perspectives in radiotherapy. While it is well known that by combining radiotherapy and chemotherapy, important therapeutic advantages can be obtained to cure cancer, there have been, so far, very few investigations on the effects of treatments combining an irradiation with high-LET particles and cancer drugs. The present study was therefore undertaken to examine the effects of exposure to 65 MeV fast neutrons combined with cisplatin in a murine T cell lymphoma (RDM4) in vitro. The cells were irradiated at doses ranging from 2 to 8 Gy without or with addition of cisplatin shortly before the irradiation, at concentrations between 0.3 and 12.5 micro M. These treatments were applied concomitantly. Proliferation and apoptosis were assessed at different time intervals thereafter. The combination of irradiation with cisplatin was found to be more cytotoxic than either treatment alone. Furthermore, the cytotoxicity induced by this cotreatment resulted not only from apoptosis but also from other forms of cell death.

Animals↗
PubMed2002

Induction of apoptosis by high linear energy transfer radiation: role of p531.

The involvement of the tumor suppressor p53 gene in the sensitivity of many cell types towards low linear energy transfer (LET) radiation is now well established. However, little information is available on the relationship between p53 status of tumor cells and their ability to undergo apoptosis following exposure to high-LET radiation. Here we present the results of experiments carried out with the human lymphoblastoid cell line TK6 and its p53 knock-out counterpart NH32. Cells were irradiated at doses ranging from 0.25 to 8 Gy with fast neutrons (65 MeV), carbon ions (95 MeV/nucleon), and X rays (15 MV). For both cell lines, the occurrence of apoptosis, determined by the quantification of hypodiploid particles as well as the activation of several caspases, was compared with their sensitivity towards high-LET radiation. Results indicate that p53 is involved in the response of TK6 cells to fast neutrons and carbon ions, as measured by cell proliferation and occurrence of apoptosis. However, p53-deficient cells are still able to undergo apoptosis following irradiation. This suggests that heavy ions and fast neutrons induce cellular damage that is not under the control of p53. The involvement of executioner caspases in high-LET radiation induced apoptosis was also evaluated by use of specific inhibitors.

Apoptosis↗
PubMed2002

Involvement of TP53 in apoptosis induced in human lymphoblastoid cells by fast neutrons.

We investigated the involvement of TP53 in apoptosis induced by fast neutrons in cells of three human B-lymphoblast cell lines derived from the same donor and differing in TP53 status: TK6 (wild-type TP53), WTK1 (mutant TP53) and NH32 (knockout TP53). Cells were exposed to X rays or to fast neutrons at doses ranging from 0.5 to 8 Gy. Apoptosis was determined by measurements of the sub-G0 /G1-phase DNA content and by the externalization of phosphatidylserine. Fast neutrons induced extensive apoptosis in TK6 cells, as shown by the formation of hypodiploid particles, the externalization of phosphatidylserine, and the activation of caspases. In contrast, cell death was triggered at a significantly lower rate in cells lacking functional TP53. However, TP53-independent cell death also expressed the morphological and biochemical hallmarks of apoptosis. Proliferation tests and clonogenic assays showed that fast neutrons can nevertheless kill WTK1 and NH32 cells efficiently. The absence of functional TP53 only delays radiation-induced cell death, which is also mediated by caspases. These results indicate that fast-neutron irradiation activates two pathways to apoptosis and that the greater relative biological effectiveness of fast neutrons reflects mainly an increase in clonogenic cell death.

Apoptosis↗
PubMed2001

Caffeine and the G2/M block override: a concept resulting from a misleading cell kinetic delay, independent of functional p53.

In the literature the sensitization of DNA to radiation-induced damage by caffeine has been attributed to an override of the G2/M block. This process was supposed to involve the tumor suppressor gene p53 as it was described that p53 negative cells were more sensitive to checkpoint inhibition by caffeine than the wildtype phenotype. We have recently shown that caffeine does not cause an override of the G2/M block induced by radiation in normal human fibroblasts. We demonstrate here that this also applies to a human transformed cell line, the thyroid carcinoma K1, when submitted to gamma- rays irradiation. Within 9 hr after irradiation over 70% of the cells accumulated in the G2/M phase. This block persisted at 16 hr. In caffeine containing cultures the percentage of cells attaining the G2/M phase was reduced by over 30% at 16 hr. This was reflected in an accumulation of the cells in G1 phase and an inhibition of the S phase traverse. Cell cycle analyses from further time points combined with cell proliferation measurements confirmed these data. These results were independent of p53 status as experiments performed with variant K1 cell lines having defective p53 functions, led to similar conclusions. In addition, caffeine restored a G1 delay after irradiation in the cell lines with abrogated p53 functions. The effects of caffeine undeniably cumulate with damages induced by irradiation but probably by inhibiting DNA repair mechanisms or by intervening with purine and pyrimidine metabolisms and not by causing a G2/M block override.

Antineoplastic Agents, Phytogenic↗
PubMed2001

A new flow cytometric method to follow DNA gap filling during nucleotide excision repair of UVc-induced damage.

BACKGROUND: Several methods have been developed for studying the kinetics of DNA repair after exposure of cells to ultraviolet (UV) light, such as conventional assays measuring unscheduled DNA synthesis (UDS). In this study, we have developed an accurate and rapid method to follow DNA gap filling during nucleotide excision repair (NER) in normal human fibroblasts (NHFs) in response to UV-induced damage. METHODS: After UVc irradiation, aphidicolin was added to the culture to hold repair patches open. This allowed an efficient incorporation of biotin-21-dUTP during an endogenous DNA repair synthesis that was detected by flow cytometry. RESULTS: We showed that the DNA gap filling after UVc irradiation in NHFs increased with time up to 10 h after irradiation and that no repair synthesis activity could be detected in XP-A fibroblasts. Furthermore, this activity was UVc dose dependent up to 20 J/m2. These results correlated well with those of the UDS assay. Interestingly, addition of aphidicolin at different time points after UVc irradiation, thus allowing endogenous repair synthesis in the absence of biotin-21-dUTP, demonstrated that the response of the NER system occurred extremely rapidly after irradiation. CONCLUSIONS: This method may be a reliable and simple alternative to other techniques measuring UDS. Practical advantages include the rapidity of the method, no need for radioactivity, and the possibility to use a second and/even a third flow marker to analyse cell cycle and heterogeneous cell populations concomitantly.

Aphidicolin↗
PubMed2001

Two metachronous tumors in the radiotherapy fields of a patient with Li-Fraumeni syndrome.

A woman with a family history of brain tumors in her daughter and sister presented with a breast cancer. She subsequently developed two metachronous primary tumors: a small-cell lung cancer and a colon carcinoma. These tumors arose within the internal mammary radiotherapy field and within the field irradiated for ovariolysis. The p53 gene was analyzed in whole blood lymphocytes using a functional assay developed in yeast Saccharomyces cerevisiae, which tests the transcriptional competence of p53. DNA from the colon cancer cells was analyzed by polymerase chain reaction and sequencing. The patient had a germline-inactivating p53 mutation, confirming the diagnosis of Li-Fraumeni syndrome (LFS). The colon tumor and the lung tumor both conserved the mutant p53 allele but had lost the wild-type allele. This observation and the experimental data suggest an abnormal sensitivity of LFS patients to radiogenic carcinogenesis. The indications and extent of radiotherapy in patients with a clinical or molecular diagnosis of LFS should be discussed individually and should take into account the risk of secondary neoplasms arising in the radiation fields.

Adult↗
PubMed2000

Caffeine does not cause override of the G2/M block induced by UVc or gamma radiation in normal human skin fibroblasts.

Caffeine has for many years been known to be involved in the sensitization of DNA to damage. One potential mechanism recently put forward is an override of the G2/M block induced by irradiation, which would leave the cells less time for DNA repair prior to mitosis. However, different cell types display a variety of responses and no clear pathway has yet emerged, especially as little is known about the capacity of this agent to enhance DNA damage in normal, untransformed cells. Continuous exposure to commonly used caffeine concentrations (1-5 mM) inhibited the proliferation of normal human fibroblasts (NHFs) in a dose-dependent manner to up to 80% at 5 mM. Exposure of exponentially growing NHFs to UVc radiation (20 J m(-2)) or gamma radiation (2.5-8 Gy) led to a 45-60% inhibition of proliferation and protracted accumulation of cells in the G2/M phase. Addition of 2 mM caffeine after irradiation induced slowing of the S phase passage, with a resultant delay in G2/M accumulation mimicking a G2/M block override. These results were confirmed by stathmokinetic studies, which showed delayed entry of the cells into mitosis in the presence of caffeine. Our data demonstrate that caffeine primarily inhibits replicative DNA synthesis and suggest that, at least in normal cells, caffeine potentiates the cytotoxicity of radiation by intervening in DNA repair rather than by overriding the G2/M block.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Efficacy and safety of docetaxel (Taxotere) in heavily pretreated advanced breast cancer patients: the French compassionate use programme experience.

The aim of this investigation was to assess retrospectively docetaxel safety and efficacy in advanced breast cancer patients in a French compassionate use programme. Patients had received > 1 prior chemotherapy regimen for advanced disease, were either anthracycline-resistant (that is progressed within 6 months after anthracycline-based chemotherapy) or had received the maximum cumulative dose. The recommended docetaxel dose was 100 mg/m2/cycle (75 mg/m2 in case of liver function impairment: transaminases > 1.5 x upper limit of normal (ULN), alkaline phosphatases > 3 x ULN). Between August 1993 and December 1995, 889 patients were treated in 67 French centres, of whom 870 were evaluable for safety and 825 were evaluable for patient and treatment characteristics and efficacy. 20.5% (of the 825 patients evaluable for baseline characteristics) had poor performance status (PS > or = 2), 49.3% liver metastasis and 9.6% biological liver dysfunction. 98.4% had been previously treated by anthracyclines, 50.8% had resistant disease and 37.1% had received > 2 prior palliative chemotherapy lines. The most frequent severe toxicity, febrile neutropenia (reported in 223/870 (25.6%) patients evaluable for safety), caused 10 deaths, 6 of these being patients with severe liver impairment before inclusion. Fluid retention syndrome and other common non-haematological toxicities were well tolerated. 3.1% (28/889) of all patients and 11.4% of those with liver dysfunction, died from treatment-related causes. The overall response rate in 825 assessable patients was 22.9% (95% confidence interval (CI): 20.2-26.2%). Median time to treatment failure was 4 months (95% CI: 3.6-4.3) and median survival was 9.8 months (95% CI: 8.8-10.7). This report on the largest series of unselected advanced breast cancer patients treated with docetaxel, supports previous phase II studies, confirming docetaxel's utility in patients relapsing after failing anthracycline-containing palliative chemotherapy.

Adult↗
PubMed1999

Cytokines in metastatic renal cell carcinoma: is it useful to switch to interleukin-2 or interferon after failure of a first treatment? Groupe Français d'Immunothérape.

PURPOSE: Interleukin-2 (IL-2) and interferon alfa-2a (IFNalpha2a) have some antitumor activity in metastatic renal cell carcinoma either alone or in combination. To determine whether either of these cytokines might be efficient after failure of the other, we analyzed a series of patients treated with either IL-2 or IFNalpha2a as second-line treatment after failure of the other cytokine. PATIENTS AND METHODS: We recently performed a large multicenter study to determine the respective efficacy of IL-2, IFNalpha2a, or combined treatment in renal cell carcinoma. In this study, patients who progressed on the single-arm treatment could receive the other cytokine in a cross-over trial. IL-2 was administered as a continuous intravenous infusion for 5 days (18 x 10(6) IU/m(2)/d), and IFNalpha2a was administered three times weekly at 18 x 10(6) IU. RESULTS: A total of 113 patients with progressive disease after first-line treatment received either IFNalpha2a (n = 48) or IL-2 (n = 65). Toxicity during second-line treatment was similar to that observed during first-line treatment. Only four partial responses were observed (one with IFNalpha2a and three with IL-2). All partial responders had a performance status of 0 and lung metastases. Moreover, three of these four patients had stable disease or had responded to first-line therapy. Only one patient with confirmed disease progression after receiving IL-2 subsequently responded to IFNalpha2a. CONCLUSION: Cross-over after failure of IL-2 or IFNalpha2a is poorly efficient in metastatic renal cell carcinoma, especially when progression has been clearly documented.

Adult↗
PubMed1999

p53-independent regulation of cyclin B1 in normal human fibroblasts during UV-induced G2-arrest.

Recently we demonstrated, using normal human fibroblasts (NHFs), that UVc radiation induces a G2/M arrest which was even more pronounced when p53 expression was inhibited. So, the aim of this study was to evaluate in NHFs the relationship between UV-induced G2/M arrest and cyclin B1 regulation and to investigate if p53 could contribute to the cyclin B1 regulation in these conditions. Following exposure of asynchronous NHFs to UV light, we showed that the induced G2/M arrest was accompanied by a dose-dependent down-regulation of cyclin B1 mRNA as evaluated by RT-PCR. Concomitantly, using flow cytometric analysis, we observed a strong accumulation of cyclin B1 protein which was correlated to the apparition of the G2/M arrest. In order to study the contribution of p53 to the cyclin B1 accumulation in response to UV exposure, we inhibited p53 induction using p53 antisense oligonucleotides. We found that the inhibition of p53 protein induction after UV exposure had no effect on the level of cyclin B1 mRNA. Moreover, although inhibition of p53 protein induction increased the number of the cells in the G2-M phase, the mean content of cyclin B1 protein was not augmented in these cells. These results indicate clearly that the induction of p53 protein following UV exposure does not regulate the level of cyclin B1 mRNA or protein in normal cells.

Cell Culture Techniques↗
PubMed1998

Inactivation of p53 in normal human cells increases G2/M arrest and sensitivity to DNA-damaging agents.

p53 mutations are found in about 70% of human cancers. In order to evaluate the role of these mutations in response to chemotherapeutic agents, it is important to distinguish between p53 response to DNA-damaging agents in normal and in tumour cells. Here, using normal human fibroblasts (NHFs), we show that cisplatin and UV radiation induce G2/M arrest which is temporally linked to p53-protein induction. To study the contribution of p53 to this G2/M arrest, we inhibited p53 induction in NHFs using p53 anti-sense oligonucleotides. Following exposure of NHFs to UV radiation, the inhibition of p53-protein induction leads to a greater accumulation of cells in the G2/M phase, but also to a decreased fraction of cells in the G1 phase. We propose that p53 does not induce G2/M arrest directly, and that the extent of this arrest may depend on the fraction of cells that do not stop at the G1 phase following exposure to DNA-damaging agents. Furthermore, inhibition of p53-protein induction leads to increased sensitivity of NHFs to UV radiation. These results suggest that inhibition of p53 protein enhances sensitivity to DNA-damaging agents in normal human cells.

Antineoplastic Agents↗
PubMed1998

Paclitaxel-anthracycline combination chemotherapy in relapsing advanced ovarian cancer after platinum-based chemotherapy: a pilot study.

Despite high response rates with platinum-based front-line chemotherapy, the prognosis for advanced ovarian carcinoma (AOC) is poor. Salvage chemotherapy for recurrent AOC was of little benefit before paclitaxel as single-agent therapy showed appreciable efficacy. Anthracyclines are effective, but are not often part of first-line therapy. In this pilot study, we investigated the feasibility of an anthracycline plus paclitaxel combination therapy for recurrent AOC. Twenty-four patients received 150 mg/m2 paclitaxel on day 1, with either 50 mg/m2 doxorubicin on day 1 or 75 mg/m2 epirubicin on day 1 every 3 weeks. A 27% overall response rate was obtained. Myelosuppression was the major toxicity, but was manageable. No myocardiac toxicity was observed. We conclude that paclitaxel-anthracyclines is a promising salvage combination therapy in AOC that should be investigated further.

Adolescent↗
PubMed1997

CD44 isoforms with exon v6 and metastasis of primary N0M0 breast carcinomas.

New isoforms of CD44 with alternatively spliced exons have recently been described. Expression of exon v6 seems to be of particular interest. It has indeed been associated with poorer outcome of breast cancer patients with node invasion at diagnosis. However, no data were available for patients N0M0 (with neither metastasis nor node invasion at diagnosis). Moreover, previous statistical analyses were realized using immunohistochemical methods to detect CD44v6 expression although several variants with exon v6 have been described. We investigated expression of isoforms containing CD44v6 using an RT-PCR approach and a panel of 25 normal breast specimens, 10 mammary fibroadenomas, 8 cystic samples and 52 primary breast tumors (38 invasive N0M0). Normal breasts, fibroadenomas, and cysts all express the same variant, A (with exon v6 only), while several transcripts are amplified in tumors. Expression of variants other than A correlates with acquisition of a malignant phenotype. Invasive cancers also express additional variants in comparison with in situ carcinomas. Metastasis capacities seem to be associated with transcription of variants other than A but also with no transcription of some of them, variants D (with exons v6 and v10) and L (with exons v6 to v10). Expression of variants D and L correlates with higher percentages of disease-free survival and better outcome. Expression of CD44 splice variants with exon v6, as detected by RT-PCR, might be a useful prognostic factor for breast cancer. However, since the series size is small, our results need to be confirmed by later studies on a larger number of patients.

Adult↗
PubMed1997

[Pharmacokinetic profile of high-dose doxorubicin administered during a 6 h intravenous infusion in breast cancer patients].

The purpose of our investigation was to evaluate the pharmacokinetic profile of doxorubicin administered by a new schedule. Nine non-pretreated young women with high risk breast cancer (mean age: 38, range: 29-45) entered this trial and received, cyclophosphamide (600 mg/m2) given as a 30-min infusion followed by doxorubicin (120 mg/m2) as a continuous infusion over 6 h. Chemotherapy was combined with hematopoietic factor support (G-CSF or GM-CSF). Blood was sampled over the 0-54 h period and 14 cycles were studied for pharmacokinetics. Doxorubicin as well as its major metabolite doxorubicinol were assayed in plasma specimen by high performance liquid chromatography. Mean doxorubicin plasma concentration peak was 42.6 ng/ml (standard deviation (SD): 13.3). The mean terminal half-lives were 32.6 h (SD: 22.0) and 39.2 h (SD: 21.6) for doxorubicin and doxorubicinol, respectively. Mean areas under the plasma concentration-time curve (AUC) were 413 ng/h-1 ml (SD: 103) and 1,707 ng/h-1 ml (SD: 815) for doxorubicin and doxorubicinol respectively. Consequently, the ratio of the AUC of doxorubicinol to that of doxorubicin was high (mean: 4.1 (SD: 1.6)) contrasting with previous studies reporting ratios less than 1 in patients with normal liver function. The systemic clearance of doxorubicin was 5.23 l/min/m2 (SD: 1.91). The inter- and intra-patient variability for AUC was low for both drugs. Hence the coefficients of variation were 24.6% for doxorubicin, 26.2% for doxorubicinol (inter-individual variation) and less than 10% for both compounds (intra-individual variation). In conclusion, the pharmacokinetic profile of doxorubicin (120 mg/m2) administered as a 6 h-continuous infusion is characterized by a greater exposure to doxorubicinol. This could be explained by a saturation in the biliary excretion process during the period following the end of the infusion.

Adult↗