Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0035412 (rhabdomyosarcoma)
 6,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rhabdomyosarcomas generally respond well to chemotherapy, and the residual lesions often are better differentiated than their primaries. This phenomenon may be explained by selective multidrug resistance (MDR) of differentiated tumor cell populations. We assess the role of MDR proteins in chemotherapy-induced differentiation in rhabdomyosarcomas in a clinical setting. Paraffin-embedded samples of 13 pairs of primary untreated rhabdomyosarcomas and their residual, recurrent, or metastatic lesions after chemotherapy were assessed for expression of MDR proteins, including P-glycoprotein (Pgp), multidrug resistance-associated protein (MRP-1), and lung resistance-related protein (LRP). Expression was semiquantitatively scored based on the percentage of isolated immunoreactive tumor cells as follows: 0, negative; 0.5, <5%; 1, 5% to 25%; 2, 26% to 50%; 3, 51% to 75%, and 4, >75%. All specimens after chemotherapy, except the late recurrences, were better differentiated than their primary, untreated specimens. Pgp or MRP-1 expression did not change significantly, but LRP expression increased significantly after chemotherapy. In both untreated and treated samples, LRP was expressed primarily in differentiated cells. The findings indicate that the in vivo expression of LRP, but not of Pgp and MRP-1, is induced by chemotherapeutic treatment in rhabdomyosarcomas. The preferential expression of LRP in differentiated cells and the subsequent more extensive expression after chemotherapy suggests that LRP plays a role in therapy-induced differentiation.
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PMID:Expression of multidrug resistance-associated proteins in rhabdomyosarcomas before and after chemotherapy: the relationship between lung resistance-related protein (LRP) and differentiation. 1261 83

Overexpression of multidrug resistance-1 (MDR-1), and multidrug resistance-associated protein (MRP) genes has been linked with resistance to chemotherapy in vitro and in vivo. Their role in chemotherapy resistance in pediatric rhabdomyosarcoma is unclear. The study was undertaken to analyze the expression of MDR-1 and MRP genes in the embryonal and the alveolar subtypes of rhabdomyosarcoma and to elucidate its clinical relevance. Twenty-three rhabdomyosarcoma samples were analyzed for the expression of MDR-1 and MRP genes using a semi-quantitative competitive RT-PCR assay. MRP gene expression was associated with a reduction in survival (p=0.02). The overall survival of patients with tumors positive or negative for MRP expression were 50% (95% confidence interval, 30-70%) and 93% (95% confidence interval, 76-100%) respectively. In contrast, the expression of MDR-1 gene was not predictive of survival. These findings suggest that MRP expression could be a prognostic factor in patients with rhabdomyosarcoma.
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PMID:Expression of multidrug resistance-1 and multidrug resistance-associated protein genes in pediatric rhabdomyosarcoma. 1465 23

Expression of multidrug resistance (MDR) proteins is thought to significantly contribute to the different biological/clinical behaviour of soft tissue sarcomas (STS) of various histological types and clinicopathological stages, as they are responsible for active efflux of cytotoxic drugs from tumour cells. We investigated the expression of 3 MDR proteins, i.e., permeability glycoprotein 1 (P-gp), multidrug resistance-associated protein 1 (MRP1) and multidrug resistance 3 (MDR3), in 43 STS specimens from newly-diagnosed paediatric patients, 31 with rhabdomyosarcoma (RMS) and 12 with non-RMS STS. To assess the influence of chemotherapy on STS drug resistance, the number of MDR-associated protein-positive cells was determined in 15 patients on both primary lesions before chemotherapy and on residual tumour after chemotherapy. At least one of the MDR-associated proteins tested was detected in 84% of primary untreated STS specimens. In these specimens, MRP1 was detected in a high percentage (70%) of the cases, followed by MDR3 in 58% and P-gp in 44%. Many specimens showed co-expression of two different MDR proteins. Interestingly, MDR3 was significantly associated with the presence of PAX3/PAX7-FKHR transcripts in RMS (p<0.05). Moreover, expression of MRP1 and MDR3 was significantly more frequent in group III and IV tumours as compared with those of groups I and II (p<0.01). After chemotherapy MRP1, MDR3 and, to a lesser extent, P-gp expression was found to be increased in most of the samples. The frequent expression of these MDR-associated proteins in primary tumour cells before chemotherapy and the increase of their levels after chemotherapy, suggest that these proteins play a pivotal role in conferring drug resistance and in producing therapy-induced differentiation on STS.
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PMID:Expression of multidrug resistance-associated proteins in paediatric soft tissue sarcomas before and after chemotherapy. 2250 34