[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.

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.

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.