Biomedical subjects

J Bourhis

Publications and source records attributed to J Bourhis.

At least 55 records · Page 3Linked to original sources

PubMed2000

A Ku80 fragment with dominant negative activity imparts a radiosensitive phenotype to CHO-K1 cells.

DNA non-homologous end joining, the major mechanism for the repair of DNA double-strands breaks (DSB) in mammalian cells requires the DNA-dependent protein kinase (DNA-PK), a complex composed of a large catalytic subunit of 460 kDa (DNA-PKcs) and the heterodimer Ku70-Ku80 that binds to double-stranded DNA ends. Mutations in any of the three subunits of DNA-PK lead to extreme radiosensitivity and DSB repair deficiency. Here we show that the 283 C-terminal amino acids of Ku80 introduced into the Chinese hamster ovary cell line CHO-K1 have a dominant negative effect. Expression of Ku(449-732) in CHO cells was verified by northern blot analysis and resulted in decreased Ku-dependent DNA end-binding activity, a diminished capacity to repair DSBs as determined by pulsed field gel electrophoresis and decreased radioresistance determined by clonogenic survival. The stable modifications observed at the molecular and cellular level suggest that this fragment of Ku80 confers a dominant negative effect providing an important mechanism to sensitise radioresistant cells.

Animals↗

PubMed2000

Radiation-induced expression of functional Fas ligand in EBV-positive human nasopharyngeal carcinoma cells.

Ionizing radiation remains a major therapeutic tool against human cancers, especially epithelial tumors, which account for the majority of human malignancies. Although Fas and Fas-L are essential determinants of apoptosis, few data support their role in the cytotoxic effect of ionizing radiation. Epstein-Barr-virus (EBV)-positive nasopharyngeal carcinoma (NPC) were chosen to address this question owing to their known sensitivity to ionizing radiation and their constitutive expression of the Fas-receptor. We here report that, in xenografted NPC cells, Fas-L expression, which was very low in basal conditions, was dramatically increased by tumor irradiation. Both the Fas receptor and the Fas ligand were found to be functional in this model, and a high proportion of irradiated NPC cells underwent apoptosis following tumor irradiation. Induction of Fas-L expression and apoptosis were observed for doses as low as 2 Gy. These data show an increase in Fas-L expression upon irradiation exposure, and strongly suggest that, in some epithelial malignancies, Fas-mediated apoptosis can play a major role in the anti-tumor effect of ionizing radiation, in the range of doses used for therapeutic applications.

Animals↗

PubMed2000

Chemotherapy added to locoregional treatment for head and neck squamous-cell carcinoma: three meta-analyses of updated individual data. MACH-NC Collaborative Group. Meta-Analysis of Chemotherapy on Head and Neck Cancer.

BACKGROUND: Despite more than 70 randomised trials, the effect of chemotherapy on non-metastatic head and neck squamous-cell carcinoma remains uncertain. We did three meta-analyses of the impact of survival on chemotherapy added to locoregional treatment. METHODS: We updated data on all patients in randomised trials between 1965 and 1993. We included patients with carcinoma of the oropharynx, oral cavity, larynx, or hypopharynx. FINDINGS: The main meta-analysis of 63 trials (10,741 patients) of locoregional treatment with or without chemotherapy yielded a pooled hazard ratio of death of 0.90 (95% CI 0.85-0.94, p<0.0001), corresponding to an absolute survival benefit of 4% at 2 and 5 years in favour of chemotherapy. There was no significant benefit associated with adjuvant or neoadjuvant chemotherapy. Chemotherapy given concomitantly to radiotherapy gave significant benefits, but heterogeneity of the results prohibits firm conclusions. Meta-analysis of six trials (861 patients) comparing neoadjuvant chemotherapy plus radiotherapy with concomitant or alternating radiochemotherapy yielded a hazard ratio of 0.91 (0.79-1.06) in favour of concomitant or alternating radiochemotherapy. Three larynx-preservation trials (602 patients) compared radical surgery plus radiotherapy with neoadjuvant chemotherapy plus radiotherapy in responders or radical surgery and radiotherapy in non-responders. The hazard ratio of death in the chemotherapy arm as compared with the control arm was 1.19 (0.97-1.46). INTERPRETATION: Because the main meta-analysis showed only a small significant survival benefit in favour of chemotherapy, the routine use of chemotherapy is debatable. For larynx preservation, the non-significant negative effect of chemotherapy in the organ-preservation strategy indicates that this procedure must remain investigational.

Antineoplastic Agents↗

PubMed2000

A randomized study of very accelerated radiotherapy with and without amifostine in head and neck squamous cell carcinoma.

PURPOSE: The aim of this study was to assess whether amifostine could minimize acute mucositis induced by a very accelerated irradiation regimen in patients with advanced head and neck squamous cell carcinoma (HNSCC). METHODS AND MATERIALS: Between May 1996 and February 1998, 26 patients with an inoperable nonmetastatic Stage IV HNSCC were entered in this study. The treatment consisted of very accelerated radiotherapy given 64 Gy in 3.5 weeks. The patients were randomized to receive or not 150 mg/m(2), amifostine (Ethyol, U.S. Bioscience) 15-30 min prior to each radiation session. RESULTS: Of the 13 patients who received amifostine, definitive interruption of amifostine occurred in 5 cases (38%), due to tolerance problems (vomiting, liver enzyme elevation, generalized erythema). The distribution of Grade 4 mucositis (WHO) was 1 case versus 8 cases, with and without amifostine, respectively. The mean duration of "at least Grade 3" mucositis (WHO) was 25.1 days versus 49.2 days with and without amifostine (p = 0.03). In the amifostine group, 11/13 of the patients required a feeding tube (nasogastric tube or medical gastrostomy), because of acute mucositis, whereas in the control group a feeding tube was necessary in all cases. The mean duration of the use of this feeding tube was 1 month versus 2.5 months with and without amifostine respectively (p < 0.01). Local-regional control was not different between both arms with a median follow-up of 15 months. CONCLUSION: Despite the limited number of patients, this pilot randomized study suggests that amifostine was able to markedly reduce the severity and duration of mucositis induced by very accelerated radiotherapy. However, the tolerance of this twice daily amifostine schedule was relatively poor.

Adult↗

PubMed2000

Radiotherapy in head and neck cancer in the elderly: a challenge.

Elderly patients represent the most rapidly growing subgroup of the patient population in France and in the majority of industrialized countries. The effect of age in terms of the prognosis and response to treatment remains unclear. The management strategy (curative versus palliative) for head and neck cancer in the elderly has given vent to divergent opinions and controversies in several respects (the type and quality of treatment, quality of life and economic consequences). This review only focuses on the radiotherapy schedule and head and neck cancers. We compare aged patients with head and neck cancer to younger patients in terms of clinical features, tumor biology, type of treatment, side effects and response. We conclude that if the patient is in a good general condition following a complete evaluation of the cancer, physicians should propose curative treatment with radiotherapy because retrospective trials demonstrate that response in older patients when treated aggressively is comparable to that of younger patients. However, specific trials concerning aged patients with head and neck cancer, quality of life and radiotherapy are warranted.

Age Factors↗

PubMed2000

Transfer of Ku86 RNA antisense decreases the radioresistance of human fibroblasts.

Ku86 has been shown to be involved in DNA double-strand break (DSB) repair and radiosensitivity in rodents, but its role in human cells is still under investigation. The purpose of this study was to evaluate the radiosensitivity and DSB repair after transfection of a Ku86-antisense in a human fibroblast cell line. Simian virus 40-transformed MRC5V1 human fibroblasts were transfected with a vector (pcDNA3) containing a Ku86-antisense cDNA. The main endpoints were Ku86 protein level, Ku DNA end-binding and DNA protein kinase activity, clonogenic survival, and DSB repair kinetics. After transfection of the Ku86-antisense, decreased Ku86 protein expression, Ku DNA end-binding activity, and DNA protein kinase activity were observed in the uncloned cellular population. The fibroblasts transfected with the Ku86-antisense showed also a radiosensitive phenotype, with a surviving fraction at 2 Gy of 0.29 compared with 0.75 for the control and 20% of unrepaired DSB observed at 24 hours after irradiation compared with 0% for the control. Several clones were also isolated with a decreased level of Ku86 protein, a surviving fraction at 2 Gy between 0.05 and 0.40, and 10-20% of unrepaired DSB at 24 hours. This study is the first to show the implication of Ku86 in DSB repair and in the radiosensitivity of human cells. This investigation strongly suggests that Ku86 could constitute an appealing target for combining gene therapy and radiation therapy.

Amino Acid Sequence↗

PubMed2000

p53-dependent G2 arrest associated with a decrease in cyclins A2 and B1 levels in a human carcinoma cell line.

In vivo transfer of wild-type (wt) p53 gene via a recombinant adenovirus has been proposed to induce apoptosis and increase radiosensitivity in several human carcinoma models. In the context of combining p53 gene transfer and irradiation, we investigated the consequences of adenoviral-mediated wtp53 gene transfer on the cell cycle and radiosensitivity of a human head and neck squamous cell carcinoma line (SCC97) with a p53 mutated phenotype. We showed that ectopic expression of wtp53 in SCC97 cells resulted in a prolonged G1 arrest, associated with an increased expression of the cyclin-dependent kinase inhibitor WAF1/p21 target gene. A transient arrest in G2 but not in G1 was observed after irradiation. This G2 arrest was permanent when exponentially growing cells were transduced by Ad5CMV-p53 (RPR/INGN201) immediately after irradiation with 5 or 10 Gy. Moreover, levels of cyclins A2 and B1, which are known to regulate the G2/M transition, dramatically decreased as cells arrived in G2, whereas maximal levels of expression were observed in the absence of wtp53. In conclusion, adenoviral mediated transfer of wtp53 in irradiated SCC97 cells, which are mutated for p53, appeared to increase WAF1/p21 expression and decrease levels of the mitotic cyclins A2 and B1. These observations suggest that the G2 arrest resulted from a p53-dependent premature inactivation of the mitosis promoting factor.

Adenoviridae↗

PubMed2000

Decreased DNA-PK activity in human cancer cells exhibiting hypersensitivity to low-dose irradiation.

Low-dose hyper-radiosensitivity (HRS) (below 0.5 Gy) has been extensively documented in the past few years. The molecular basis of this phenomenon remains largely unknown and the purpose of this study was to investigate the possible implication of the DNA repair DNA-PK complex. The activity of the DNA-PK complex, i.e. Ku DNA-end binding activity and kinase activity of the whole complex, was studied in 10 human cancer cell lines, 2 h after 0.2, 0.5 and 1 Gy irradiation. After low-dose irradiation (0.2 Gy), a marked decrease in DNA-PK activity was found in all six cell lines exhibiting HRS, whereas the DNA-PK activity was increased in the four cell lines which did not exhibit HRS. This modulation of DNA-PK activity was a rapid phenomenon occurring within the 2 h following low-dose radiation exposure. These data strongly suggest the implication of the DNA-PK repair complex in the HRS phenomenon.

Amino Acid Sequence↗

PubMed2000

[Biomodulation and radiotherapy].

Recent improvement in the understanding of the mechanisms involved in the response to ionizing radiation have made it possible to identify new therapeutic targets to increase the anti-tumor efficacy or, alternatively, to decrease the effect on normal tissues. These approaches included targeting genes involved in the regulation of radio-induced DNA-repair and cell death as well as genes involved in the regulation of radio-induced apoptosis. Many other molecular targets have been recently identified to potentially interfere with the response to ionizing radiation, such as some cell membrane growth factor receptors (EGFr, TGFb) or molecules involved in intra-cellular signal transduction pathways, cell cycle regulation, etc. In addition, other promising ways to modulate radiation-induced response concern extracellular or tissue factors such as hypoxia and angiogenesis.

Antineoplastic Agents↗

PubMed1999

The value of pretreatment cell kinetic parameters as predictors for radiotherapy outcome in head and neck cancer: a multicenter analysis.

PURPOSE: The aim of this study was to assess the potential of pre-treatment cell kinetic parameters to predict outcome in head and neck cancer patients treated by conventional radiotherapy. MATERIALS AND METHODS: Data from 11 different centers were pooled. Inclusion criteria were such that the patients received radiotherapy alone, and that the radiotherapy was given in an overall time of at least 6 weeks with a dose of at least 60 Gy. All patients received a tracer dose of either iododeoxyuridine (IdUrd) or bromodeoxyuridine (BrdUrd) intravenously prior to treatment and a tumor biopsy was taken several hours later. The cell kinetic parameters labeling index (LI), DNA synthesis time (Ts) and potential doubling time (Tpot) were subsequently calculated from flow cytometry data, obtained on the biopsies using antibodies against I/BrdUrd incorporated into DNA. Each center carried out their own flow cytometry analysis. RESULTS: From the 11 centers, a total of 476 patients conforming to the inclusion criteria were analyzed. Median values for overall time and total dose were 49 days and 69 Gy, respectively. Fifty one percent of patients had local recurrences and 53% patients had died, the majority from their disease. Median follow-up was 20 months; being 30 months for surviving patients. Multivariate analysis revealed that T-stage, maximum tumor diameter, differentiation grade, N-stage, tumor localization and overall time correlated with locoregional control, in decreasing order of significance. For the cell kinetic parameters, univariate analysis showed that only LI was significantly associated with local control (P=0.02), with higher values correlating with a worse outcome. Ts showed some evidence that patients with longer values did worse, but this was not significant (P=0.06). Tpot showed no trend (P=0.8). When assessing survival in a univariate analysis, neither LI nor Tpot associated with outcome (P=0.4, 0.4, respectively). Surprisingly, Ts did correlate with survival, with longer values being worse (P=0.02). In the multivariate analysis of local control, LI lost its significance (P=0.16). CONCLUSIONS: The only pretreatment kinetic parameter for which some evidence was found for an association with local control (the best end-point for testing the present hypothesis) was LI, not Tpot, and this evidence disappeared in a multivariate analysis. It therefore appears that pretreatment cell kinetic measurements carried out using flow cytometry, only provide a relatively weak predictor of outcome after radiotherapy in head and neck cancer.

Analysis of Variance↗

PubMed1999

Meta-analyses in head and neck squamous cell carcinoma. What is the role of chemotherapy?

Despite more than 70 randomized clinical trials comparing locoregional treatment plus chemotherapy with the same locoregional treatment alone, the effect of chemotherapy on the survival of patients with head and neck squamous cell cancer is uncertain. Indeed, most of the randomized trials have been inconclusive in this regard, and only a few have reported significant results either in favor of or against chemotherapy. This article focuses on four meta-analyses that included a comparison between chemotherapy (neoadjuvant, adjuvant, or concomitant) plus locoregional treatment versus the same locoregional treatment alone and in which survival was the main end-point.

Antineoplastic Agents↗

PubMed1999

Cross-resistance to ionizing radiation in a murine leukemic cell line resistant to cis-dichlorodiammineplatinum(II): role of Ku autoantigen.

cis-Dichlorodiammineplatinum(II) (CDDP; cisplatin) is commonly used in combination with ionizing radiation (IR) in the treatment of various malignancies. In vitro, many observations suggest that acquisition of CDDP resistance in cell lines confers cross-resistance to IR, but the molecular mechanisms involved have not been well documented yet. We report here the selection and characterization of a murine CDDP-resistant L1210 cell line (L1210/3R) that exhibits cross-resistance to IR because of an increased capacity to repair double-strand breaks compared with parental cells (L1210/P). In resistant cells, electrophoretic mobility shift assays revealed an increased DNA-end binding activity that could be ascribed, by supershifting the retardation complexes with antibodies, to the autoantigen Ku. The heterodimeric Ku protein, composed of 86-kDa (Ku80) and 70-kDa (Ku70) subunits, is the DNA-targeting component of DNA-dependent protein kinase (DNA-PK), which plays a critical role in mammalian DNA double-strand breaks repair. The increased Ku-binding activity in resistant cells was associated with an overexpression affecting specifically the Ku80 subunit. These data strongly suggest that the increase in Ku activity is responsible for the phenotype of cross-resistance to IR. In addition, these observations, along with previous results from DNA-PK- mutant cells, provide evidence in favor of a role of Ku/DNA-PK in resistance to CDDP. These results suggest that Ku activity may be an important molecular target in cancer therapy at the crossroad between cellular responses to CDDP and IR.

Animals↗

PubMed1998

[Biological principles of chemoradiotherapy].

Radio-chemotherapy combinations, especially their concomitant associations, are widely used in the treatment of cancer. The development of these associations has been so far related more to clinical research than to laboratory experiments. The biological basis of the use of these agents relies on their complementarity which concerns the cellular and molecular mechanisms involved in lethality (hypoxia, sensitivity throughout the cycle, DNA repair, apoptosis), spatial and temporal cooperation, etc. Laboratory experiments can determine favorable conditions for additivity, or supra-additivity, but also for infra-additive interactions as well as real antagonism which should be avoided in the clinic. It is however often difficult to transfer this information into the clinic since the conditions which allow additivity or supra-additivity are generally very narrow, and unlikely to be realised in the patient. General clinical conditions are more compatible with infra-additive interactions.

Animals↗

PubMed1998

[Chemoradiotherapy of carcinomas of the upper aerodigestive tract].

The objective of this study was to review randomized trials which evaluated the effect of the radio-chemotherapy in head and neck carcinoma, and which compared radiotherapy alone vs the same local treatment plus chemotherapy. Over 40 such randomized trials have been performed, which generally showed no statistical difference between both arms. However few trials showed a benefit which is almost always in favor of the CT arm. Indeed, some trials of concomitant chemoradiotherapy have shown a statistically significant benefit in favor of the combined treatment. On the contrary, neoadjuvant chemotherapy generally leads to no detectable benefit compared to radiotherapy alone. These results have been reinforced by those of four randomized trials comparing neoadjuvant chemoradiotherapy and the same chemotherapy but given concomitantly with radiotherapy. The global effect of chemotherapy on survival of patients with head & neck squamous cell carcinoma has been recently evaluated by a meta-analysis based on individual patient data which included more than 10,000 patients from 63 randomized trials. The absolute survival rate benefit at 5 years is 4%, but is more pronounced in the concomitant combinations (8% at 5 years). In tumors classified as "T3" of the pharyngo-larynx, neoadjuvant chemotherapy followed by radiotherapy in good responders can avoid a total laryngectomy without significantly compromised survival. In the nasopharynx carcinoma, a few randomized studies have been performed, suggesting a benefit in favor of chemoradiotherapy. Finally, future randomized trials will determine what are the optimal chemoradiotherapy schedules, as well as determining what is the best radiotherapy (accelerated, hyperfractionated) to use in combination with chemotherapy.

Antineoplastic Agents↗

PubMed1998

Aesthesioneuroblastoma.

Forty patients were treated or followed up for aesthesioneuroblastoma between 1980 and 1995 at Institut Gustave Roussy, France. There were three T1, seven T2, 15 T3 and 15 T4 lesions. The cervical metastatic rate at presentation was 18 per cent. Distant metastases were detected by bone marrow biopsy and bone scan in three patients at presentation. Treatment modalities included surgery alone in eight patients, radiotherapy alone in three patients, combined modality surgery plus radiotherapy in 11 patients, chemotherapy alone in two patients, chemotherapy plus radiotherapy in 10 patients, and multimodality therapy chemotherapy plus surgery plus radiotherapy in six patients. The five-year survival rate was 51 per cent. Multimodality treatment offered better survival (63 per cent at five years) and disease-free interval (54 months). Overall local, regional, and distant failure rates were 58 per cent, 15 per cent and 40 per cent respectively. Distant metastases commonly occurred in bone (82 per cent). Cervical metastasis was an unfavourable prognostic indicator (0 per cent survival at two years). In conclusion, aesthesioneuroblastoma is sensitive to chemotherapy and radiotherapy. Multimodality therapy should be used initially.

Adolescent↗

PubMed1998

Full-dose reirradiation for unresectable head and neck carcinoma: experience at the Gustave-Roussy Institute in a series of 169 patients.

PURPOSE: To review our experience using full-dose external reirradiation given with a curative intent for patients with unresectable head and neck carcinoma (HNC). PATIENTS AND METHODS: Between January 1980 and December 1996, 169 patients who presented with unresectable nonmetastatic HNC in a previously irradiated area were included in this series. The median time between the first and the second irradiation was 33 months. Reirradiation protocols were as follows: radiotherapy alone (65 Gy over 6.5 weeks at 2 Gy/d), 27 patients; Vokes protocol, ie, five to six cycles of radiotherapy (median total dose, 60 Gy; 2 Gy/d) with simultaneous fluorouracil (5-FU) and hydroxyurea, 106 patients; and bifractionated radiotherapy (median total dose, 60 Gy; 2 x 1.5 Gy/d) with concomitant mitomycin, 5-FU, and cisplatin, 36 patients. The median cumulative dose of the two irradiations was 120 Gy. Eighty-five percent of the tumors were squamous cell carcinoma, 14% undifferentiated carcinoma of nasopharyngeal type, and 1% adenocarcinoma. Forty-four percent were local recurrences, 23% nodal recurrences, 14% both local and nodal, and 19% second primary tumors. RESULTS: Mucositis grade 3 (World Health Organization [WHO]) was found in 32% and grade 4 in 14% of cases. Four patients presented with neutropenia or thrombocytopenia (grade 3 or 4 WHO). Late toxicities (> 6 months) were as follows: cervical fibrosis (grade 2 to 3 Radiation Therapy Oncology Group [RTOG]), 41%; mucosal necrosis, 21%; osteoradionecrosis, 8%; and trismus, 30%. Five patients died of carotid hemorrhage, apparently in complete remission. Six months after the onset of reirradiation, 37% of patients were in complete response. Patterns of failure were local only (53%), nodal only (20%), metastatic only (7%), and multiple (20%). Median follow-up time was 70 months. Overall survival rate (Kaplan-Meier) was 21% (95% confidence interval [CI], 15% to 29%) at 2 years and 9% (95% CI, 5% to 16%) at 5 years. Median survival time was 10 months for the entire population. Thirteen patients, of whom 12 were treated with the Vokes protocol, were long-term disease-free survivors. In a multivariate analysis, the volume of the second irradiation was the only factor significantly associated with the risk of death: relative risk=1.8 (95% CI, 1.13 to 5.7) (P=.01). CONCLUSION: Full-dose reirradiation combined with chemotherapy was feasible in patients with inoperable HNC. The incidence and severity of late toxicity was markedly increased in comparison to that observed after the first irradiation. Median survival was better than that generally obtained using palliative chemotherapy alone. A small proportion of patients were long-term disease-free survivors.

Adult↗

PubMed1998

[Importance of a multidisciplinary approach to metastatic cancer of the rectum].

Management of rectal cancers with synchronous metastasis is difficult. We evaluated in 23 patients a combination of pelvic radiotherapy at the dose of 45 Gy in 5 weeks and 25 fractions with chemotherapy by 5-fluorouracil (350 mg/m2/day) and folinic acid (20 mg/m2/day) for 5 days at the time of the first and the fifth week of the irradiation. Surgery was indicated firstly in cases of stricture or secondarily for resection of the primary location and, when possible, of the metastasis. General state of health of the patients improved in 35%, symptomatology in 86% and comfort in 72% of the cases. Response rates for the primary tumor were 41% of partial response and 50% of stable disease. For the metastatic lesions, they were 9% and 59% respectively. Sixty-one per cent of patients were secondarily operated with resection of the primary tumor in 12 cases and of hepatic metastases in 2 cases. The median survival and the median survival without progression were respectively 13 and 9 months. Radiochemotherapy combination as the first treatment was beneficial in 4/5 of the patients presenting a rectal cancer with synchronous metastasis and allowed us to select those that would secondarily benefit from a surgical resection.

Adult↗

PubMed1998

[Oncogenic factors of metastatic dissemination in neuroblastoma].

Disseminated neuroblastoma frequently show a very poor prognosis. N-myc gene amplification, 1p deletion and lack of CD44 gene expression, are all genetic factors associated with the disease's dissemination. Human neuroblastoma xenografts in nude mice has permitted to characterize, in disseminated neuroblasts, oncogenes overexpression, inactivation of tumor suppressor genes as well as detoxifying genes activation which contributes to increase cellular resistance to chemotherapy. These genetic abnormalities permit to propose a nosology of this very aggressive pediatric solid tumor. Hopefully, this genetic classification could be of great value for new therapeutic approaches.

Animals↗