Biomedical subjects

Denis Larsimont

Publications and source records attributed to Denis Larsimont.

6 recordsLinked to original sources

PubMed2003

Decrease of estrogen receptor expression and associated ERE-dependent transcription in MCF-7 breast cancer cells after oligomycin treatment.

Oligomycin at 0.01 microM produces very rapid decrease of [3H]estradiol (E2)-binding capacity in MCF-7 cells maintained in culture in glucose- and serum-free medium. Loss of binding capacity was associated with elimination of the estrogen receptor (ER) as well as a decrease of basal expression of ERE-luciferase reporter gene. These effects were not due to major cell death as shown by MTT assay. Hence, the inhibition of ATP synthesis produced by oligomycin seems to influence ER turnover, resulting in very rapid loss of receptor. Withdrawal of oligomycin and maintenance of glucose in the medium led to only a partial reappearance of ER and failed to restore optimal ERE-dependent transcription. Oligomycin significantly down-regulated progesterone receptor (PR) level and partially abrogated E2-induced PR up-regulation, indicating that this drug also affects other nuclear receptors. Treatment of cytosol from MCF-7 cells with acid and alkaline phosphatases decreased [3H]E2-binding capacity, indicating the requirement of ER phosphorylation for optimal hormone binding. On the other hand, oligomycin-induced ER loss was partly compensated by E2 and partial anti-estrogens (AEs; 4-OH-TAM or RU 39 411); i.e. oligomycin failed to improve the E2-induced ER down-regulation and very weakly suppressed partial AE-induced receptor up-regulation. The known ability of these ligands to stabilize ER in the cell nucleus before regulating ER level may explain this phenomenon since such antagonism was not recorded with pure AE RU 58 668, which is known to impede nuclear translocation of the receptor. Interestingly, ligands able to down-regulate ER (i.e. E2 or RU 58 668) increased ER phosphorylation while 4-OH-TAM which up-regulate the receptor had little effect in this regard. Oligomycin failed to strongly affect such phosphorylation enhancements while it produced a weak decrease of basal phosphorylation level. Hence, phosphorylations/dephosphorylations of specific sites on ER and/or co-regulators seem to govern its turnover.

Binding Sites↗

PubMed2002

Predictive molecular markers in the adjuvant therapy of breast cancer: state of the art in the year 2002.

In the present article, an extensive review of the current knowledge regarding predictive molecular markers in breast cancer is presented. The main emphasis has been given to the adjuvant therapy setting, because of the lack of well-designed studies evaluating predictive markers in the metastatic setting. In the first part of the article some general concepts have been summarized, mainly to emphasize the difference between prognostic and predictive markers. In the second part of the article, studies evaluating molecular markers with predictive value for the most commonly used drugs or regimens (i.e., cyclophosphamide, methotrexate, 5-fluorouracil [CMF], anthracyclines, taxanes, and herceptin) have been reviewed and discussed. An attempt has been made to provide for each single predictive marker the currently available level of evidence, to allow the reader to have immediate information regarding the impact of the evaluated marker in daily clinical practice. In the last part of the article, the most important findings have been summarized and future avenues of research have been outlined.

Antineoplastic Agents↗

PubMed2002

Evaluation of HER-2/NEU protein expression in breast cancer by immunohistochemistry: an interlaboratory study assessing the reproducibility of HER-2/NEU testing.

This study investigated the degree of interlaboratory agreement when HER-2/neu was evaluated by immunohistochemistry (IHC) on archival primary breast cancer samples. IHC for HER-2/neu was performed on the same archival tissue sections from 394 invasive primary breast cancers in two different laboratories. Both laboratories used the primary antibody NCL-CB11; however, different methods of immunostaining (antigen retrieval procedure and manual processing or no antigen retrieval and autostainer processing) as well as different scoring systems were used. Fluorescence in situ hybridization (FISH), considered as the correlation method for HER-2/neu status determination, was performed using the PathVysion kit and compared to the IHC results. Forty-eight of 394 analyzed tumors (12.2%) were scored as HER-2/neu positive in one laboratory, and 109 (27.7%) in the other laboratory where antigen retrieval was performed. Complete concordance in categorization of HER-2/neu status between the two laboratories was achieved in 333 of 394 cases (84.5%). FISH performed in 248 formalin-fixed samples revealed HER-2/neu gene amplification in 55/248 (22.2%). Concordance of FISH and IHC was found in 211/248 cases (85.1%) and 220/248 cases (88.7%) when the CB11 antibody was used without and with antigen retrieval, respectively. Both IHC methods generated similar rates of false results, but with different positive predictive values. Our data demonstrate that HER-2/neu evaluation by IHC is not a reproducible technique if there is no standardization of the procedure.

Breast Neoplasms↗

PubMed2002

Microtubule-associated parameters as predictive markers of docetaxel activity in advanced breast cancer patients: results of a pilot study.

Docetaxel is currently one of the most active agents for breast cancer. Predictive markers of docetaxel efficacy are clearly needed in order to avoid unnecessary toxicity in nonresponding or resistant patients and to improve the cost-effectiveness ratio of docetaxel. This pilot study correlates the clinical efficacy of docetaxel in 54 metastatic or locally advanced breast cancer patients with the expression of microtubule-associated parameters evaluated by immunohistochemistry in archival tumor samples. Among the 41 eligible patients (evaluable response to docetaxel and available predocetaxel treatment paraffin-embedded tumor tissue), response to docetaxel was: partial response 54%, stable disease 29%, and progressive disease 17%. Alfa- and b-tubulin and Tau protein were expressed in the majority of tumor samples. Class II, III, and IV b-tubulin isotypes were expressed in 56%, 65%, and 82% of samples, respectively. No clear association was found between response to docetaxel and the level of expression of Tau protein, a- and b-tubulin, and class III and IV b-tubulin isotypes. In patients with class II b-tubulin-positive tumors, the response rate was 39%, while in class II b-tubulin-negative tumors the response rate was 79% (P = 0.04). Therefore, we conclude that the class II b-tubulin isotype seems to be a promising predictive marker of docetaxel activity. Nevertheless, further investigations are needed due to the limited number of patients evaluated in this pilot study.

Adult↗

PubMed2002

HER-2 amplification and topoisomerase IIalpha gene aberrations as predictive markers in node-positive breast cancer patients randomly treated either with an anthracycline-based therapy or with cyclophosphamide, methotrexate, and 5-fluorouracil.

PURPOSE: The purpose of this study is to evaluate HER-2 and topoisomerase IIalpha (topo IIalpha) as candidates for predicting the activity of anthracyclines in the adjuvant treatment of breast cancer patients. EXPERIMENTAL DESIGN: In this study, we evaluated HER-2 and topo IIalpha gene aberrations by fluorescence in situ hybridization in a series of 430 primary breast cancer samples. Samples came from node-positive breast cancer patients randomly treated either with one of two anthracycline-based regimens [full-dose epirubicin-cyclophosphamide (HEC) and moderate-dose epirubicin-cyclophosphamide (EC)] or with cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) in the context of a Phase III adjuvant therapy trial. Event-free survival comparisons were performed between the three study arms in the subgroups of HER-2-amplified and nonamplified tumors. An explorative analysis was also performed to evaluate the predictive value of topo IIalpha in the cohort of HER-2-amplified patients. RESULTS: HER-2 amplification was observed in 73 of the 354 evaluable samples (21%), whereas topo IIalpha amplification was found in 23 of the 61 evaluable HER-2-amplified tumors (38%). The three event-free survival comparisons were CMF versus HEC, CMF versus EC, and EC versus HEC. Hazard ratios (HRs) and 95% confidence intervals (CIs) were as follows: (a) CMF versus HEC, HR = 1.42 for HER-2-amplified tumors (95% CI, 0.54-3.76; P = 0.48) and 0.84 for HER-2-nonamplified tumors (95% CI, 0.49-1.44; P = 0.53); (b) CMF versus EC, HR = 1.65 for HER-2-amplified tumors (95% CI, 0.66-4.13; P = 0.29) and 0.66 for HER-2-nonamplified tumors (95% CI, 0.39-1.10; P = 0.11); and (c) EC versus HEC, HR = 0.93 for HER-2-amplified tumors (95% CI, 0.31-2.77, P = 0.90) and 1.33 for HER-2-nonamplified tumors (95% CI, 0.82-2.14; P = 0.25). Observed HRs suggest that the anthracycline-based therapy could be more effective than CMF in the subgroup of HER-2-amplified patients, whereas treatments could be equally active in the HER-2-nonamplified cohort. topo IIalpha evaluation suggests that the superiority of anthracyclines over CMF in HER-2-amplified patients could be confined to the subgroup of topo IIalpha-amplified tumors. CONCLUSIONS: HER-2 could have a predictive value for the activity of anthracycline-based regimens in the adjuvant therapy of breast cancer patients. The predictive value of HER-2 would most likely be related to the concomitant amplification of the topo IIalpha gene.

Aged↗

PubMedDate not supplied

HER-2/neu evaluation by immunohistochemistry and fluorescence in situ hybridization in breast cancer: implications for daily laboratory practice.

BACKGROUND: HER-2/neu status was determined by immunohistochemistry (IHC) and fluorescence in situ hybridisation (FISH) methods in more than 300 paraffin-embedded primary breast cancer samples. MATERIALS AND METHODS: HER-2/neu status was determined by FISH using the PathVysion kit (Vysis) and by IHC using either a monoclonal antibody CB11 or a cocktail of antibodies: the monoclonal TAB250 and the polyclonal pAb1. RESULTS: Of the 324 cases evaluable by IHC, 65 out of 318 (20%) and 24 out of 324 (7%) were scored as positive when using the antibody cocktail and the CB11, respectively. HER-2/neu gene amplification occured in 64 out of 324 cases (20%). Concordance of FISH and IHC was found in 285 out of 318 cases (90%) and 278 out of 324 cases (86%) using the cocktail and the CB11, respectively. CONCLUSION: The cost-effectiveness analysis revealed that the use of a sensitive IHC method followed by confirmation of positive results by FISH considerably decreased the FISH costs and may become standard practice for HER-2/neu evaluation.

Antibodies, Monoclonal↗