Chunxi Wang

p53 Mutations and Prognosis in Bladder Tumors

The incidence of loss of heterozygosity on chromosome 17p and p53 gene mutations was assessed in 43 bladder tumor patients. Histological findings, cigarette smoking and prognosis were examined for possible correlation with the presence or absence of loss of heterozygosity on 17p and p53 mutations. Of 20 informative cases 10 (50.0%) showed loss of heterozygosity of 17p13, including 9 (90.0%) with disease beyond stage pT2. The p53 mutations were detected in 20 of 43 patients (46.5%), including 9 (95.0%) with disease beyond grade 2 and 17 (85.0%) with cancer beyond stage pT2. The incidence of p53 gene mutations was not significantly influenced by habitual smoking but G:C to T:A substitutions, often observed in lung cancers, were detected only in mutations from smokers (5 of 10 or 50%, p < 0.05). Groups with and without loss of heterozygosity showed essentially the same results, while significant differences were found for groups with grades 1 and 2 to 3 (p < 0.05) cancer, stages pT1 and pT2 to 4 (p < 0.01) disease, and with and without p53 gene mutations (p < 0.01, Cox-Mantel test). Genetic alternation in chromosome 17p and p53 mutations would, thus, appear to occur more frequently in high grade and invasive bladder tumors. Cigarette smoking may possibly be a determining factor of mutations of the p53 gene in bladder tumors. Our results indicate that an unfavorable prognostic factor may possibly be linked not only to histopathological findings but the presence of a p53 mutation in bladder tumors as well. Accordingly, mutations of the p53 gene may be deeply involved in late events of tumorigenesis and possibly useful as ideal molecular markers for prognosis in bladder tumors.

Clinical significance of p53, mdm2, and bcl-2 proteins in renal cell carcinoma.

OBJECTIVES To improve our understanding of the clinical relevance of p53, mdm2, and bcl-2 protein overexpression in renal cell carcinoma, we retrospectively investigated the immunohistochemical expression of p53, murine double minute 2 (mdm2), and bcl-2 and the relationship of this expression to clinicopathologic characteristics. p53 regulates the transcription of downstream effectors such as the oncoprotein mdm2, and bcl-2 has been shown to inhibit apoptosis triggered by wild-type p53. METHODS The expression of p53, mdm2, and bcl-2 protein was studied by immunohistochemical methods in paraffin-embedded nephrectomy specimens from 112 patients whose clinicopathologic data confirmed renal cell carcinoma. RESULTS The expression of the p53 and bcl-2 protein was recognized in 15 (13.4%) and 52 (42.0%) cases, respectively; the expression of the mdm2 protein, however, was seen in only 2 cases (1.8%). No correlation was noted between these three proteins and any clinicopathologic parameters, except p53 expression and Stage T1-2/T3-4 (P = 0.0208). However, in multivariate analysis, stage (hazard ratio 3.586; P = 0.0002), expression of p53 (hazard ratio 6.090; P = 0.0126) and of mdm2 (hazard ratio 22.016; P = 0.0156), and coexpression of p53/mdm2 (hazard ratio 6.146; P = 0.0005) demonstrated a statistically significant effect on prognosis by proportional hazards regression tests. CONCLUSIONS Our results indicate that stage, p53 expression, mdm2 expression, and coexpression of p53/mdm2 are useful to predict the clinical outcome in patients with renal cell carcinoma.

MICROSATELLITE INSTABILITY IN TRANSITIONAL CELL CARCINOMA OF THE URINARY TRACT AND ITS RELATIONSHIP TO CLINICOPATHOLOGICAL VARIABLES AND SMOKING

To determine whether microsatellite instability is involved in the development of transitional cell carcinoma (TCC) of the urinary tract, a microsatellite instability assay was carried out using PCR with 9 microsatellite loci. Thirty‐eight TCC samples (30 patients with bladder cancer, 5 with renal pelvic tumors and 3 with ureteral tumors) and 1 lymph node with metastasis were examined. Microsatellite instability was found in 8 of 38 tumors examined, and 3 showed alterations in more than 2 microsatellite loci. All 8 tumors were beyond grade 2 and stage pT2 advanced tumors. Stages pT1‐2 and pT3‐4 patients differed significantly. Microsatellite instability was greater in smokers than non‐smokers, but the differences were not significant. Microsatellite instability in TCC of the urinary tract is rare in superficial tumors but more common in invasive tumors. Microsatellite alterations would thus appear to occur, and possibly be importantly involved, in the tumorigenesis of urinary tract TCC.

BRCA1 gene mutation and loss of heterozygosity on chromosome 17q21 in primary prostate cancer

The tumor suppressor gene BRCA1 on chromosome 17q21 has been characterized and shown to be mutated in patients with familial breast and ovarian cancer. Several studies examined the relatives of women with breast cancer and noted an association with ovarian and prostate cancer. This study investigated 24 human prostate cancer specimens for BRCA1 gene mutations and loss of heterozygosity (LOH) on chromosome 17q21 assessed by the polymerase chain reaction. LOH was identified using 7 highly polymorphic tandem repeat markers on chromosome 17q21, in addition to an analysis of the whole coding region of the BRCA1 gene. Four of the 24 prostate cancer specimens showed LOH at one or more loci, all of which were histologically poorly differentiated (4 of 11) and stage D (4 of 15). One of the 24 cases showed a germ‐line mutation of the BRCA1 gene, and a sister of this patient died of ovarian cancer. It appears that the BRCA1 gene is not frequently involved in the development of primary prostate cancer. Int. J. Cancer (Pred. Oncol.) 84:19–23, 1999.

Antitumor effect of bcl-2 antisense phosphorothioate oligodeoxynucleotides on human renal-cell carcinoma cells in vitro and in mice.

BACKGROUND AND PURPOSE Programmed cell death is a genetically regulated pathway that is altered in many cancers. This process is, in part, regulated by the bcl-2 oncogene. Antisense oligodeoxynucleotides (ODNs) targeted to specific oncogenes have been used with some therapeutic success in animal models of leukemia and melanoma cells and human Hodgkins lymphoma. We evaluated the effects of antisense ODNs targeted to the bcl-2 oncogene on the proliferation of human renal-cell carcinoma (RCC) cells in vitro and on the growth of human RCC xenografts in BALBc nude (nu/nu) mice. MATERIALS AND METHODS Expression bcl-2 mRNA in five RCC cell lines (ACHN, Caki-1, RCZ, RCW, and OS-RC-2) was analyzed by reverse transcriptase-polymerase chain reaction. The effects of phosphorothioated ODNs containing human bcl-2 sense and bcl-2 antisense sequences that were transfected with Lipofectin on the proliferation and viability of cultures of established human RCC cell lines were determined by MTS assay. The expression of Bcl-2 protein in ACHN tumor cells following antisense bcl-2 (AS2) ODN treatment was evaluated by Western blot analysis, and the extent of apoptosis in these cells was determined by fluorescence-activated cell sorter (FACS) analysis. The antitumor activity in ACHN xenografts in nu/nu mice was monitored by measuring differences in tumor weight in treated and control mice. RESULTS Expression of bcl-2 mRNA was detected in all five RCC lines. Treatment with antisense bcl-2 ODNs inhibited the growth of all tested RCC cells and decreased Bcl-2 protein expression in ACHN cells. The AS2 antisense ODN complementary to the coding region of bcl-2 mRNA showed a superior antiproliferative effect compared with AS1 ODN complementary to the translation initiation region. Inhibition by antisense bcl-2 ODNs of ACHN cells was dose dependent. The FACS analysis revealed that growth inhibition was associated with the induction of programmed cell death. In vivo, AS2 ODN antitumor activity was noted in locally injected groups. CONCLUSIONS Treatment of human RCC with antisense ODNs targeted to bcl-2 inhibits growth and is associated with the induction of programmed cell death. These results suggest therapeutic use of antisense bcl2 in the treatment of RCC.