p53 immunopositivity in histologically favorable Wilms tumor is not related to stage at presentation or to biological aggression

p53 Immunohistochemistry expression in Wilms tumor: a prognostic tool in the detection of tumor aggressiveness

PURPOSE

We studied whether immunohistochemical expression of p53 in Wilms tumors correlates with tumor aggressiveness. We also examined whether preoperative chemotherapy results in any alteration of p53 expression.

MATERIALS AND METHODS

A total of 18 patients underwent preoperative chemotherapy and 30 underwent immediate surgery for Wilms tumor. All children were younger than 10 years and had histologically confirmed disease. Patients with a bilateral tumor or a syndrome related to Wilms tumor were excluded. All pathology slides were uniformly stained for p53 protein, and p53 staining density and intensity were scored. The p53 scoring was then compared to the clinical behavior of the Wilms tumor, ie unfavorable tumor staging, and survival and recurrence rates.

RESULTS

In the direct surgery and the preoperatively treated groups p53 positivity correlated with unfavorable Wilms tumor staging (p = 0.007). In addition, a positive p53 correlation predicted poorer survival (p = 0.017). Interestingly patients who underwent preoperative chemotherapy had an increased intensity of p53 staining compared to the direct surgery group (p <0.001).

CONCLUSIONS

This study provides preliminary evidence that a higher score for immunohistochemical p53 expression correlates with unfavorable Wilms tumor staging and predicts poorer survival. This test could become a useful addition to the current histopathological analysis of Wilms tumor.

Apoptotic protein expression in favorable-histology Wilms tumor correlates with tumor recurrence

PURPOSE

Outcome for patients with Wilms tumor (WT) with favorable histology is good. Deletions of chromosomes 1p and 16q impart a poorer outcome. Value of apoptotic protein expression is not clear.

METHODS

Expression of four immunohistochemically detectable apoptosis-regulating proteins (bcl-2, bcl-x, bax and p53) were analyzed in 30 specimens of WT and compared to recurrence and recurrence-free survival (RFS).

RESULTS

The 30 patients included ranged from 4 to 72 months in age (mean 31). The mean available follow-up was 35.3 months (range 1-54). Six patients developed recurrence. The 5-year RFS for blastema-predominant tumors was 40% as compared to 91% for triphasic histology which was significant (p = 0.048). The 5-year RFS in patients with bcl-2 negative tumors was 63% as compared to 100% for bcl-2 positive tumors, the difference being significant (p = 0.019). The 5-year RFS in patients with p-53 positive tumors was 27% as compared to 91% for p-53 negative tumors; however, this difference in the RFS was not statistically significant (p = 0.143). bax and bcl-x expression were not related to the RFS.

CONCLUSIONS

Tumors that are bcl-2 negative have a relatively higher recurrence rate and a poorer RFS. They may benefit from a more intensive follow-up regime for early detection of recurrence.

Decrease in LDL receptor-related protein expression and function correlates with advanced stages of Wilms tumors

BACKGROUND

The molecular processes responsible for the invasive phenotype of pediatric Wilms tumors (WT) are poorly understood. A candidate WT suppressor gene (WT1) has been found mutated in a number of these pediatric kidney tumors. However, the disruption of normal WT1 protein function cannot solely explain WT growth. The aim of the present study is to identify new molecular players that regulate the invasive character of WT.

PROCEDURE

Fresh frozen samples from 45 renal tumors of Wilms were obtained from the National Wilms Tumor Study Group's Biological Samples Bank. Gelatin zymography, Western blotting, and immunodetection were used to compare tissue biopsies originating from the infiltrating (stage III), metastatic (stage IV), and anaplastic phenotype of Wilms tumors (WT).

RESULTS

The expression of the low-density lipoprotein receptor-related protein (LRP) diminished in stage IV and anaplastic WT. Moreover, the expression of RAP, an LRP intracellular chaperone, was also decreased. The diminished expression of LRP and RAP correlated with increased levels of several known extracellular ligands that LRP usually recycles from the extracellular matrix (ECM) environment, including PAI-1, MMP-9, and TIMP-1. The proteolytic processing of MT1-MMP, a functional regulator of LRP, also correlated with the WT invasive phenotype.

CONCLUSIONS

The low expression of LRP, whose function is regulated by MT1-MMP and whose activity in recycling ECM-associated proteolytic enzymes becomes drastically diminished in advanced stages of WT, may in part explain the acquired invasive potential of the developing WT pediatric cancer.