MVP immunohistochemistry is a useful adjunct in distinguishing leiomyosarcoma from leiomyoma and leiomyoma with bizarre nuclei.

Morphologically, distinguishing between leiomyoma (LM) and leiomyosarcoma (LMS) is not always straightforward, especially with benign variants such as bizarre leiomyoma (BLM). To identify potential markers of malignancy in uterine smooth muscle tumors, proteomic studies were performed followed by assessment of protein expression by immunohistochemistry. Archival formalin-fixed, paraffin-embedded tissues from tumors (n = 23) diagnosed as LM, BLM, and LMS (using published criteria) were selected for the study. Sequential window acquisition of all theoretical fragment ion spectra mass spectrometry was applied to pooled samples of formalin-fixed, paraffin-embedded LM and LMS tumor tissue to assay the relative protein quantities and look for expression patterns differentiating the 2 tumor types. A total of 592 proteins were quantified, and 10 proteins were differentially expressed between LM and LMS. Select proteins were chosen for evaluation by immunohistochemistry (IHC) based on antibody availability and biologic relevance in the literature. IHC was performed on a tissue microarray, and intensity was evaluated using imaging software. Major vault protein (MVP) and catechol O-methyltransferase had 3.05 and 13.94 times higher expression in LMS relative to LM by sequential window acquisition of all theoretical fragment ion spectra mass spectrometry, respectively. By IHC, MVP (clone 1014; Santa Cruz Biotechnology, Dallas, TX) was found to be 50% sensitive and 100% specific when comparing LMS to LM. Catechol O-methyltransferase (clone FL-271; Santa Cruz Biotechnology) had a sensitivity of 38% and a specificity of 88%. Six of 7 BLM had expression of MVP similar to LM. Immunohistochemical staining for MVP is a useful adjunct in distinguishing LMS from LM and BLM in difficult cases.

[Effects of cyclooxygenase-2 selective inhibitor celecoxib on the expression of major vault protein in rats with status epilepticus].

OBJECTIVE: To study the effect of cyclooxygenase -2 selective inhibitor celecoxib on the expression of major vault protein ( MVP) in the brain of rats with status epilepticus and its possible roles in the treatment of refractory epilepsy. METHODS: Sixty adult male Sprague-Dawley rats were randomly assigned to blank control (n=16), epilepsy model (n=22) and celecoxib treatment groups (n=22). After the status epilepticus was induced in rats by injecting lithium and pilocarpine, each group had 16 rats enrolled as subjects. Immunohistochemical method and Western blot method were used to detect the expression of MVP in the frontal cortex and hippocampus. RESULTS: The expression of MVP was significantly higher in the epilepsy model group than in the control group (P<0.01). The expression of MVP in the celecoxib treatment group was significantly decreased compared with the epilepsy model group, but it was still higher than in the control group (P<0.01). CONCLUSIONS: Celecoxib could decrease the expression of MVP in brain tissue of rats with status epilepticus, suggesting that it is promising for the treatment of intractable epilepsy.

The Expression of Lung Resistance Protein in Saliva: A Novel Prognostic Indicator Protein for Carcinoma of the Breast.

Considering that saliva is a fluid inundated with proteins, it is possible that solubilized oncogenic proteins may be present in saliva and may be useful in differentiating between healthy and diseased individuals. As a consequence, the purpose of this study was to determine if the solubilized form of LRP was present in stimulated whole saliva and could differentiate between 16 healthy women and 16 women with confirmed Stage I breast cancer. LRP levels were determined using gel electrophoresis and Western blot technology. The results showed LRP at significantly higher concentrations among breast cancer subjects as compared to healthy women.

Importance of detecting multidrug resistance proteins in acute leukemia prognosis and therapy.

Multidrug resistance (MDR) is a multifactorial phenomenon and the role of these proteins in generating the MDR phenotype is controversial. With this in mind, this review compiled the current data on the role of ABCB1, ABCC1, and LRP proteins in the prognosis of hematologic neoplasms and their influence on the choice of therapy. Literature showed that the detection of these proteins, mainly ABCB1, is important in the AL prognosis. However, there is controversy regarding the methodology used for their detection. In summary, the expression and activity profiles of ABCB1, ABCC1, and LRP, proteins capable of promoting the efflux of a variety of chemotherapeutic agents from the cell cytoplasm represent one of the greatest causes of failure in AL treatment.

The expression and significance of MRP1, LRP, TOPOIIß, and BCL2 in tongue squamous cell carcinoma.

BACKGROUND: Multiple drug resistance protein 1 (MRP1), lung resistance protein (LRP), topoisomerase IIß (TOPOIIß) and B-cell lymphoma 2 (BCL2) are well known in the development of drug resistance in cancer cells. The aim of this study was to evaluate the relationship between them and the clinicopathological features, their expression differences between tumor tissue and experimental drug-resistant model in tongue carcinoma. MATERIALS AND METHODS: Multiple drug resistance protein 1, LRP, TOPOIIß, and BCL2 expression was examined by immunohistochemistry in specimens from radical surgeries of 65 patients with tongue carcinoma. A cisplatin-resistance cell line, SCC-15/cisplatin, was established from a cisplatin-sensitive cell line, SCC-15. A MTT-based method was used to analyze drug potencies. Immunofluorescence was used to detect protein expression in both cell lines. Western blot was used to compare the protein expressions in specimens and SCC-15/cisplatin cells. RESULTS: We found higher expression of MRP1, LRP, and BCL2 and lower expression of TOPOIIß in tongue carcinoma compared with adjacent non-neoplastic tongue tissues (P < 0.05). In addition, MRP1 and TopoIIß expression were significantly associated with clinical stage, lymph node metastasis and histologic grade, and LRP was significantly associated with histologic grade in the samples (P < 0.05). Finally, Western blot showed that higher expressions of MRP1, LRP, and BCL2 and lower expression of TopoIIß were observed in SCC-15/cisplatin cells than in clinical samples. CONCLUSION: Our results suggest that the high expressions of MRP1, LRP, and BCL2 and low expression of TOPOIIß in patients with tongue carcinoma indicates that intrinsic drug resistance may exist in tongue carcinoma, and is associated with tumor differentiation and cisplatin resistance in tongue carcinoma.

Expression and clinical significance of multidrug resistance proteins in brain tumors.

BACKGROUND: To investigate the mechanisms of multidrug resistance of brain tumors, to identify the site of cellular expression of P-gp in human brains in situ and to morphologically determine whether an association may exist between P-gp and caveolin-1. METHODS: Immunohistochemistry was used to detect the expression and location of P-glycoprotein (P-gp), multidrug resistance-associated protein (MDR), lung resistance-related protein (LRP), topoisomerase II (Topo II) and glutathione-S-π (GST-π) in 30 patient tumor tissues and 5 normal brain tissues. The sections were subjected to double labeling for P-gp (TRITC labeled) and caveolin-1 (FITC labeled). The location and characteristics of expression of the two proteins in the blood brain barrier(BBB) was observed using a laser scanning microscope. RESULTS: High expression of P-gp was detected in vessel walls and the tissue surrounding the vessels. However, expression of P-gp was low in tumor cells. The expression of the other 4 multidrug resistance proteins was not observed in the vessel walls. Laser scanning microscopy showed P-gp and caveolin-1 co-expression: the two proteins co-localized either in the luminal endothelial compartment or at the border of the luminal/abluminal compartments. CONCLUSION: Chemotherapeutics drugs are interrupted in the end-feet of neuroepithelial cells of the BBB by P-gp, which weakens the chemotherapeutic effect. P-gp marks the BBB, and the transporter is localized in the luminal endothelial compartment where it co-localizes with caveolin-1.

Use of multiple biological markers in radiotherapy-treated head and neck cancer.

OBJECTIVE: Management of patients with head and neck squamous cell carcinoma is often based on clinical parameters, with little appreciation of the underlying tumour biology. Single biological marker studies fail to acknowledge the complexity of these tumours. Our aim was to define a profile of biological markers associated with outcome. DESIGN: This retrospective study involved consecutive patients with oropharyngeal squamous cell carcinoma treated with primary radiotherapy between 1996 and 2001. Pre-treatment biopsies were used to study the immunohistochemical expression of nine biological markers. Markers were chosen to reflect biologically relevant pathways. RESULTS: Following analysis of nine markers, a profile of two markers was derived (carbonic anhydrase 9 and major vault protein), the co-expression of which conferred a significantly poor probability of locoregional control. The prognostic effect of these biomarkers in combination was greater than their effect individually. CONCLUSION: Biomarker profiles can be established which highlight large differences in locoregional control. Identifying tumours that express both carbonic anhydrase 9 and major vault protein may facilitate patient selection for more aggressive treatment.

Expression of multidrug resistance-related proteins p-glycoprotein, glutathione-s-transferases, topoisomerase-II and lung resistance protein in primary gastric cardiac adenocarcinoma.

BACKGROUND/AIMS: Multidrug resistance (MDR) is closely correlated to an unfavorable prognosis in various human cancers. However, the clinical significance of the expression of MDR-related proteins p-glycoprotein (PGP), glutathione-s-transferases (GST-pi), topoisomerase-II (Topo-II) and lung resistance protein (LRP) in primary gastric cardiac adenocarcinoma (PGCA) remains unclear. In this study, the total of the four kinds of MDR-related proteins mentioned above were detected by using immunohistochemistry and their clinical significance in chemoresistance were also investigated. METHODOLOGY: This retrospective study included 69 resected specimens from patients with PGCA. The expression of PGP, GST-pi, Topo-II and LRP in formalin-fixed paraffin-embedded tissue sections was determined by a labelled streptavidin-biotin immunohistochemical technique, and the results were analyzed in correlation with clinicopathological data. None of these patients received chemotherapy prior to surgery. RESULTS: The positive rates of expression of PGP, GST-pi, Topo-II and LRP in malignant tissues (49.2%, 75.4%, 68.1% and 58%, respectively) were all higher than that of the normal tissues (0, 30%, 20% and 0, respectively, P<0.01). PGP expression in tumors that had metastasized was significantly more frequent than in tumors that had not metastasized (67.5% vs. 24.1%, P<0.01).The expression of PGP was closely related with clinicopathologic staging (staging 1/2 vs. 3/4, 28.6% vs. 58.3%, P<0.05). No significant correlation was shown between PGP and increasing differentiated degree (40%, 42.4% and 61.5%, P>0.05). GST-pi expression status progressively increased with increasing differentiated degree (40%, 75.8% and 88.5%, P<0.05) and clinico pathologic stage (staging 1/2 vs. 3/4, 57.1% vs. 83.3%, P<0.05). In addition, a significant positive correlation was also observed between GST-pi and lymphatic metastasis (with vs. without metastasis, 87.5% vs. 58.6%, P<0.05). The expression of Topo-II was associated with increasing differentiated degree (33.3%, 69.7% and 80.7%, P<0.01). No significant differences with Topo-II expression was found in relation to the clinicopathologic stage (staging 1/2 vs. 3/4, 57.1% vs. 72.9%, P>0.05) and lymphatic metastasis (with vs. without metastasis, 65.0% vs. 72.4%, P>0.05). Moreover, a significant difference with the expression of LRP was found in relation to the clinicopathologic stage (staging 1/2 vs. 3/4, 38% vs. 66.6%, P<0.05), and lymphatic metastasis (with vs. without metastasis, 70.0% vs. 41.4%, P<0.05). Comparing the well, moderately and poorly differentiated cohort, a non-statistical increasing trend towards LRP expression status was noted (50.0%, 54.5% and 65.3%, respectively, P>0.05). Besides, the co-expression of all four tested MDR-related proteins also existed. The positive rates of co-expression of PGP and GST-pi, PGP and Topo-II, PGP and LRP, GST-pi and Topo-II, LRP and GST-pi, LRP and Topo-II, PGP, GST-pi, Topo-II and LRP in malignant cells were 23.2%, 15.9%, 11.6%, 13.0%, 26.1%, 7.24%, 5.8%, respectively. CONCLUSIONS: MDR-related proteins PGP, GST-pi, Topo-II and LRP are involved in multiple mechanisms of drug resistance in PGCA. Combined determination of PGP, GST-pi, Topo-II and LRP may be prospectively valuable for optimizing the chemotherapy regimes, developing high quality anti-cancer drugs, and further predicting the outcomes of those patients with PGCA.

Immunohistochemical detection of MDR proteins in Wilms' tumour.

OBJECTIVES: The aim of our work was to determine the expression of three MDR proteins (MDR1/Pgp, MRP1 and LRP/MVP) in 15 tissue samples of nephroblastoma (Wilms' tumour). BACKGROUND: The majority of Wilms' tumours respond well to chemotherapy and are successfully cured, but a small subset displays resistance to therapy. The molecular mechanisms of drug resistance in this tumour type of childhood are still poorly analyzed. In our opinion, the elucidation of reasons for therapy failure in nephroblastomas is urgently needed before cure becomes a reality for children with this cancer. METHODS: To demonstrate these proteins the enzyme indirect immunohistochemical method was used. The brown colour of the diaminobenzidine reaction product allowed us to define the distribution of stain clearly. CONCLUSION: Our immunohistochemical analysis did not demonstrate any expression of MDR1 in all cases of nephroblastoma (14 cases were after pre-operative chemotherapy, 1 case wasn't). The analysis of MRP1 and LRP expression in our set revealed 60% positivity for MRP1 and 26.7% positivity for LRP. The ability to recognize the multidrug resistance phenotype might assist in choosing specific chemotherapeutic regimens to improve prognosis and therapy (Tab. 2, Fig. 2, Ref. 20). Full Text (Free, PDF) www.bmj.sk.