Expression of P-glycoprotein restricted to normal cells in neuroblastoma biopsies

Abstract

Summary Immunohistological detection of P-glycoprotein (P-gp) with monoclonal antibody C219 was performed on serial sections of 37 neuroblastoma specimens representative of the different forms of the disease, from stage 1 ganglioneuroma to stage 4 neuroblastoma. Malignant cells, irrespective of their degree of maturation varying from neuroblasts to ganglion cells, were negative on all specimens. The expression of P-glycoprotein was detected in nine specimens, but it was restricted to normal cells within the tumour. In four specimens, C219 reacted with normal infiltrating cells in the stroma (i.e. monocytes, histiocytes or fibroblasts) representing 5 to 10% of the total population within the section; in three specimens, the residual adrenal gland was strongly positive, and in two ganglioneuromas, a weak reactivity of C219 was observed on a few satellite cells and schwann cells. Three of 15 biopsies obtained at diagnosis contained normal P-gp positive cells: two were classified as stage 1 ganglioneuromas; one was a typical stage 4 composite tumours with positive histiocytes and fibroblasts in the well-differentiated counterpart. Six of 22 biopsies obtained after patients had received our current protocol of chemotherapy contained normal P-gp positive cells: five were partially differentiated and necrotic under the effect of chemotherapy; only one positive specimen was classified as undifferentiated neuroblastoma. Among negative specimens from previously treated patients, one was obtained from a patient in relapse after high-dose chemotherapy and ABMT, two were obtained from patients who had not responded to induction therapy, and six from patients in partial remission after induction therapy. The clinical evolution was very similar in both groups of patients with P-gp negative or positive biopsies.These findings suggest that the quantitative assessment of MDR RNA by northern blotting on fresh homogenates is likely to overestimate its expression on neuroblastoma cells, and that the mechanism of chemoresistance in widespread neuroblastoma is less likely to be associated with P-gp expression.The relationship between the overexpression of the 170 kD cell membrane glycoprotein (P-glycoprotein) and the phenomenon of multidrug resistance (MDR) has been clearly demonstrated in human tumour cell lines; P-glycoprotein (P-gp) functions as a drug-efflux pump which can be reversed in vitro by calcium channel blockers such as Verapamil (Gerlach et al., 1986;Rothenberg & Ling, 1989). The overexpression of P-gp has been well documented in a number of tissues, including liver, colon, kidney and adrenal gland, in untreated human malignancies arising from these tissues, as well as in a variety of tumours after treatment (Bell et al., 1985;Gerlach et al., 1987;Ma et al., 1987;Epstein et al., 1989;Lai et al., 1989;Merkel et al., 1989;Thiebaut et al., 1989; CordonCardo et al., 1990;Weinstein et al., 1990;Miller et al., 1991). However, a meaningful relationship between the overexpression of P-gp and the resistance of these tumours to ch...

MYCN-mediated regulation of the MRP1 promoter in human neuroblastoma

“…However, in clinical NB studies, conflicting reports exist regarding the prognostic value of MDR1 expression (Goldstein et al, 1990;Chan et al, 1991;Norris et al, 1996). Although P-glycoprotein expression was reported to be a predictor of outcome of therapy for NB patients in some studies (Goldstein et al, 1990;Chan et al, 1991), other series have failed to show any correlation (Favrot et al, 1991;Norris et al, 1996). In one study, high levels of MDR1 expression were found to be predictive of outcome only in older children with NB tumors that lacked MYCN amplification .…”

“…In one study, high levels of MDR1 expression were found to be predictive of outcome only in older children with NB tumors that lacked MYCN amplification . Furthermore, in contrast to MRP1, the level of expression of MDR1 is lower in tumors with MYCN amplification compared to those without amplification (Nakagawara et al, 1990;Favrot et al, 1991;Norris et al, 1996). Thus, the contribution, if any, of MDR1 expression to the drugresistant phenotype of MYCN-amplified NB tumors remains unclear.…”

Quantitative determination of mdr1 gene expression in leukaemic cells from patients with acute leukaemia

“…In sarcoma of childhood and neuroblastoma, expression of P-glycoprotein determined with the monoclonal antibody C219 was found to be an important prognostic factor (Chan et al, 1991;. Another group using the same monoclonal antibody found that P-glycoprotein expression was restricted to normal cells in neuroblastoma biopsies (Favrot et al, 1991). In P-glycoprotein positive resistant multiple myeloma verapamil has been shown to increase the effect of vincristine, doxorubicin and prednisone chemotherapy in some but not all patients (Salmon et al, 1991 The patients were treated between 1982 and 1991 and received combination chemotherapy according to different protocols.…”

Multidrug resistance in pediatric oncology

“…The disparity and variability in published reports may be due to the many different methods used for analysis of Pgp [15][16][17][18][19][20][21][22][23][24] or MDR1 expression [25][26][27][28][29][30][31] in tumor specimens. Pgp expression has been measured using different immunodetection techniques (Western blot, immunohistochemistry and flow cytometry).…”

“…These investigators suggested that Pgp expression may be predictive of outcome in nonlocalized neuroblastoma. In another report of 37 cases (22 specimens obtained after treatment and 15 obtained at diagnosis) by Favrot and coworkers, Pgp was analyzed using immunohistochemistry with mAb C219 and no detectable staining was noted in malignant cells in all of these specimens [18]. However, these investigators noted immunostaining of the stromal cell component 9 of the 37 specimens.…”