Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.3.44 (P-glycoprotein)
 13,344 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previously, we identified P-glycoprotein in primary gastroesophageal adenocarcinomas and in adjacent mucosa. This study is a further investigation of P-glycoprotein expression in adenocarcinomas and benign mucosa. Sixteen resection specimens were studied (seven for gastric adenocarcinoma, seven for esophageal adenocarcinoma, one for adenocarcinoma at the gastroesophageal junction, and one for severe dysplasia in Barrett's esophagus). Multiple samples of tumor and mucosa were submitted according to a specimen diagram. Lymph node and distant metastases were studied when available. P-glycoprotein expression was identified in paraffin-embedded tissues by immunohistochemistry using monoclonal antibody C219 and was scored as the percentage of cells stained. P-glycoprotein was identified in six of 16 resection specimens. Intratumoral variability of C219 score was noted in three resections. No increase in expression was identified in lymph node or distant metastases as compared with primary tumors or in the invasive margin of the tumor as compared to the center. For every case in which tumors expressed P-glycoprotein, it was also diffusely present in all types of benign gastric and Barrett's mucosa, both adjacent to and distant from (up to 8 cm) the tumor. We also studied biopsies from 10 patients with Barrett's esophagus who did not have carcinoma. P-glycoprotein was only focally present in one of the 10 biopsies. Mucosa expressing P-glycoproteins may be the substrate from which a P-glycoprotein positive tumor arises.
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PMID:P-glycoprotein expression in gastroesophageal adenocarcinomas, their metastases, and surrounding mucosa: a mapping study. 172 84

The resistance of malignant tumors to chemotherapy is often associated with overexpression of the multidrug resistance gene MDR. Its gene product, P-glycoprotein, acts as a drug efflux pump for chemotherapeutic agents. The authors studied MDR expression in 28 adenocarcinomas arising in Barrett's esophagus (EAs) using a monoclonal antibody directed against this gene product. The results were compared with MDR expression in 27 gastric adenocarcinomas (GAs). P-glycoprotein was detected in both tumor and normal mucosa in 7 of 27 GAs and in 6 of 10 EAs that were resected without prior chemotherapy. Chemotherapy was given before surgical resection in 18 of the EAs studied. Five patients had a partial response to chemotherapy, and one had a complete eradication of his carcinoma; all of these tumors were negative for P-glycoprotein. Of 12 patients without chemotherapy response, 6 had tumors that expressed P-glycoprotein. The authors conclude that P-glycoprotein is present in EAs and GAs before exposure to chemotherapy. The presence of P-glycoprotein in tumors usually correlates with its presence in the adjacent mucosa. Its presence in tumor cells may be an indicator of lack of sensitivity to chemotherapy.
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PMID:Expression of a multidrug resistance gene in esophageal adenocarcinoma. Correlation with response to chemotherapy and comparison with gastric adenocarcinoma. 239 10