Detection of P53 tumor-suppressor-gene protein in bladder tumors and prostate cancer: possible clinical implications

Overexpression of p53 delivered using recombinant NDV induces apoptosis in glioma cells by regulating the apoptotic signaling pathway

Malignant glioma is the most common primary brain carcinoma in the world and has a poor survival rate. Previous studies have demonstrated that p53 dysfunction contributes to the development and severity of malignant glioma. It has also been demonstrated that Newcastle disease virus (NDV) may be a viable candidate for the treatment of various types of cancer. In the present study, a p53 oncolytic agent delivered using recombinant NDV (rNDV-p53) was constructed and its anti-tumor effects in vitro and in vivo were assessed. Glioma cell lines and a xenograft mouse model were utilized to assess the ability of p53 and rNDV to promote apoptosis and induce immunotherapy, respectively. The mechanism of rNDV-p53 in glioma therapy was investigated using quantitative polymerase chain reaction and immunohistochemistry. Tumor-specific cytotoxic T-lymphocyte (CTL) responses and lymphocyte infiltration were also analyzed in glioma-bearing models. The results of the present study demonstrate that rNDV-p53 may be a potential therapeutic agent that improves the prognosis of mice with glioma. It was revealed that rNDV-p53 inhibits glioma cell growth and aggressiveness in vitro and in vivo compared with rNDV and p53 alone. The results also demonstrated that rNDV-p53 induced glioma cell apoptosis by upregulating apoptosis-related genes. In addition, the present study demonstrated that rNDV-p53 significantly stimulated CTL responses and lymphocyte infiltration whilst increasing the number of apoptotic bodies in vivo. Furthermore, rNDV-p53 therapy inhibited tumor regression and prolonged the survival of glioma-bearing mice. In conclusion, rNDV-p53 invoked an immune response against glioma cells, which may serve as a comprehensive immunotherapeutic schedule for glioma.

The effects of interleukin 2 and rAd-p53 as a treatment for glioblastoma

Interleukin 2 (IL-2) is an anti-cancer cytokine that stimulates T cell propagation, triggering innate and adaptive immunity. IL-2 has been used for cancer therapy and has achieved curative effects. Recombinant adenovirus p53 injection (rAd‑p53) is a gene therapeutic agent that may improve the prognosis of patients with glioblastoma (GBM). In the present study, the effect of combined IL‑2 and rAd‑p53 treatment was studied. The ability of IL‑2 to stimulate immunoregulation and the ability of p53 to induce apoptosis for GBM was researched in the GBM tumor model. In addition, the activity of IL‑2 was analyzed. The antitumor potential of IL‑2 and rAd‑p53 was studied using xenograph mice carrying GBM cells. Tumor‑specific CD4+ and CD8+ T cells were also analyzed in the GBM‑bearing models. The results demonstrated that IL‑2 and rAd‑p53 not only stimulated tumor‑specific cytotoxic T‑lymphocyte responses and increased regulatory CD4+ and cytotoxic CD8+ T cell proliferation, however additionally increased expression of apoptosis‑associated genes. The treatment with IL‑2 and rAd‑p53 resulted in tumor regression and prolonged the survival of glioma‑bearing mice. Taken together, a combination of IL‑2 and rAd‑p53 treatment combines the effects of immunotherapy and oncolytic therapy and may be a comprehensive therapeutic schedule for clinical application in future cancer therapies.

Assessment of the extent of unpublished studies in prognostic factor research: a systematic review of p53 immunohistochemistry in bladder cancer as an example

OBJECTIVES

When study groups fail to publish their results, a subsequent systematic review may come to incorrect conclusions when combining information only from published studies. p53 expression measured by immunohistochemistry is a potential prognostic factor in bladder cancer. Although numerous studies have been conducted, its role is still under debate. The assumption that unpublished studies too harbour evidence on this research topic leads to the question about the attributable effect when adding this information and comparing it with published data. Thus, the aim was to identify published and unpublished studies and to explore their differences potentially affecting the conclusion on its function as a prognostic biomarker.

DESIGN

Systematic review of published and unpublished studies assessing p53 in bladder cancer in Germany between 1993 and 2007.

RESULTS

The systematic search revealed 16 studies of which 11 (69%) have been published and 5 (31%) have not. Key reason for not publishing the results was a loss of interest of the investigators. There were no obviously larger differences between published and unpublished studies. However, a meaningful meta-analysis was not possible mainly due to the poor (ie, incomplete) reporting of study results.

CONCLUSIONS

Within this well-defined population of studies, we could provide empirical evidence for the failure of study groups to publish their results that was mainly caused by loss of interest. This fact may be coresponsible for the role of p53 as a prognostic factor still being unclear. We consider p53 and the restriction to studies in Germany as a specific example, but the critical issues are probably similar for other prognostic factors and other countries.

p53 in noncancerous bladder mucosa as a marker of disease recurrence in patients with superficial transitional cell carcinoma of the bladder

We investigated the prevalence and clinical relevance of p53 nuclear overexpression in histologically benign bladder mucosa in patients with superficial transitional cell cancer (TCC) of the bladder to look for "premalignant" lesions as the source of tumor recurrence. p53 Accumulation in representative tumor and normal-looking bladder mucosa was studied in 53 patients with Ta and T1 TCC. Histologically normal bladder specimens from 20 prostate cancer patients served as controls. We used a biotin streptavidine-peroxidase system to stain deparaffinized tissue sections with the p53 monoclonal antibody DO7. Specimens from 42 (79%) of the 53 TCC patients stained for p53 in the tumor area. There was no statistically significant difference between pTa and pT1 lesions (pTa, 71.4%; pT1, 87.5%), and staining correlated weakly with tumor grade (G1, 62%; G2, 82%; G3, 100%). Evaluation of histologically normal bladder mucosa showed positive p53 staining in 13 (24.5%) of the 53 patients. Disease recurred in 20 patients. Among them, 12 had positive staining in the normal bladder mucosa. Although p53 expression in tumor areas showed only slight correlation with tumor recurrence (p = 0.043, Cochran-Armitage test), p53 accumulation in healthy bladder mucosa correlated strongly with disease recurrence (p < 0.0001, Fisher's exact test). p53 Overexpression in histologically normal bladder mucosa in patients with TCC might identify premalignant alterations in tumor-surrounding areas. Our data suggest that p53 accumulation in histologically benign bladder mucosa of TCC patients is a possible marker of disease recurrence.

Prognostic value of MCM2 immunoreactivity in stage T1 transitional cell carcinoma of the bladder

OBJECTIVE

Due to the heterogeneous biologic behavior of stage T1 bladder carcinomas, there is a need for new markers allowing to assess the prognosis more accurately. To our knowledge, there are no reports on studies investigating minichromosome maintenance protein 2 (MCM2) expression in bladder carcinomas. Thus, we investigated the prognostic value of MCM2 immunoreactivity in stage T1 bladder tumors.

METHODS

Fifty-four tumors were analyzed using Biochip microarrays. Also p53 and Ki67 antigen expression were examined. Immunohistochemical scores were compared with the clinical outcome.

RESULTS

During a median follow-up of 43 months, tumor recurrence was registered in 43 and progression to stage T2 in 19 patients. Kaplan-Meier curves demonstrated that high-level MCM2 expression was significantly associated with early tumor recurrence when using a cutoff of 60% (p=0.0035 by log-rank test), and with early tumor progression when using a cutoff of 20% (p=0.0454). There was no relationship (p=0.604) between MCM2 and p53, but a tendentious relationship (p=0.082) between MCM2 and Ki67 antigen expression. MCM2 (p=0.006), Ki67 antigen (p=0.035) and p53 expression (p=0.049) as well as tumor grade (p=0.026) and age (p=0.025) were found significantly associated with recurrence-free survival by univariate Cox regression analysis, among which only Ki67 antigen expression (p=0.015) and age (p=0.019) proved to be of independent predictive value by multivariate analysis. Concerning tumor progression, MCM2 expression was identified as the only predictive parameter by log-rank test, but it was not of independent predictive value by multivariate analysis (p=0.101).

CONCLUSION

Our data suggest that MCM2 expression may bear some prognostic relevance in stage T1 bladder carcinomas.

Utilization of polymerase chain reaction technology in the detection of solid tumors

BACKGROUND

Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic lesions. Generally, for a positive result, these detection assays require that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods for detecting a small number of cancer cells. Over the past few years, numerous clinical studies have used PCR techniques to detect physical alterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression of genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of solid tumors is reviewed.

METHODS

A review of the literature on the clinical utility of PCR and RT-PCR in the detection of solid tumor micrometastasis was conducted.

RESULTS

Amplification by PCR is a highly sensitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approximately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-based assays have been used to detect cancer cells in biopsies of solid tissue, lymph nodes, bone marrow, peripheral blood, and other body fluids. Several studies have reported a high specificity and sensitivity of tumor marker detection and a high correlation between PCR results and the presence of metastatic disease. However, in a few studies, PCR assays have not consistently demonstrated a higher sensitivity and specificity of detection than traditional modalities for many types of cancer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies.

CONCLUSIONS

PCR can detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Reports from various study groups have lacked uniformity in their protocols, and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patients remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve as a useful adjunct to clinical decision-making in the future.

Utilization of polymerase chain reaction technology in the detection of solid tumors

BACKGROUND

Most cancer detection tests currently performed are based on either antibody assays to a marker protein with altered expression in cancer patients or on imaging studies to identify characteristic lesions. Generally, for a positive result, these detection assays require that a tumor have a significant volume of cancer cells. Advances in diagnostic techniques and technology may allow for cancer detection at earlier stages, when the tumor burden is smaller and potentially more curable. The molecular techniques of polymerase chain reaction (PCR) and reverse transcriptase PCR (RT-PCR) are highly sensitive methods for detecting a small number of cancer cells. Over the past few years, numerous clinical studies have used PCR techniques to detect physical alterations of genes, such as mutations, deletions, translocations and amplification, the presence of oncogenic viruses, and the expression of genes specific to tissue, cancer, and metastasis. The current status of PCR as a method for detecting marker genes in the management of solid tumors is reviewed.

METHODS

A review of the literature on the clinical utility of PCR and RT-PCR in the detection of solid tumor micrometastasis was conducted.

RESULTS

Amplification by PCR is a highly sensitive method to determine gene expression. A single cell expressing a tumor marker among 10-100 million lymphocytes can be detected by the PCR assay. This approach has been used to detect tumor cells in approximately 18 different solid tumor types, with melanoma and carcinoma of the breast and prostate the most widely investigated to date. PCR-based assays have been used to detect cancer cells in biopsies of solid tissue, lymph nodes, bone marrow, peripheral blood, and other body fluids. Several studies have reported a high specificity and sensitivity of tumor marker detection and a high correlation between PCR results and the presence of metastatic disease. However, in a few studies, PCR assays have not consistently demonstrated a higher sensitivity and specificity of detection than traditional modalities for many types of cancer. There has been a wide range in sensitivity and specificity among the studies, which may be partly attributed to the lack of uniformity among the PCR protocols used in different studies.

CONCLUSIONS

PCR can detect tumor marker-expressing cells that are otherwise undetectable by other means in patients with localized or metastatic cancer. Reports from various study groups have lacked uniformity in their protocols, and this has prevented adequate comparison. The clinical utility of this assay as a tool for the prognosis and management of cancer patients remains and area of active investigation. PCR is a powerful tool in the study of the biology of cancer metastasis and will likely serve as a useful adjunct to clinical decision-making in the future.

Detection of tumor-derived DNA in exfoliated cells of urine sediments with a novel quantitative PCR method based on allele-specific PCR

We have established a novel quantitative method based on the allele-specific PCR, which uses the linearly amplified fragment of the PCR products as the internal control. The improved characteristics of the procedure are the high sensitivity for quantitation of the mutant alleles at ratios of up to 1:10000 and the reduced necessity of the optimization of the PCR conditions for each mutation. Using this modified allele-specific PCR, we could quantify the tumor alleles in the urine sediments of three patients with urothelial cancers that harbored different p53 gene mutations. This method can be applied to other genetic targets that have other types of alterations, such as deletions or insertions.

Nuclear p53 overexpression in bladder, prostate, and renal carcinomas

BACKGROUND

The aim of this study was to examine nuclear p53 overexpression in transitional cell carcinoma of the bladder, adenocarcinoma of the prostate, and renal cell carcinoma.

METHODS

Forty-four pathologic specimens from 39 bladder cancer patients, 41 prostatic adenocarcinoma, and 39 renal cell carcinoma specimens were analyzed immunohistochemically with D07 monoclonal antibody to detect the expression of the mutant p53 gene. Overexpression was said to occur when the number of positively-stained tumor nuclei were > or = 10% in each specimen. p53 overexpression was correlated with the clinical and histopathological features of these cancers.

RESULTS

Nuclear p53 overexpression occurred in 18.2% of transitional cell bladder cancer specimens, 12.2% of prostate cancer specimens, and 17.9% of renal cell cancer specimens. Statistical analyses showed that grade, vascular invasion, and necrosis in bladder cancer, a high Gleason score in prostate cancer, and the 1-year mortality rate in renal cancer were significantly related with p53 nuclear overexpression (P < 0.05).

CONCLUSION

Using the D07 monoclonal antibody, nuclear p53 overexpression is relatively uncommon in urologic malignancies, and moderately correlates with several histopathological and clinical features of urologic malignancies.

Prognostic value of p53 in muscle-invasive bladder cancer treated with preoperative radiotherapy

OBJECTIVES

The relationship of p53 mutations as analyzed immunohistochemically to radiation response and therapeutic outcome was examined in a cohort of 301 patients with muscle-invasive transitional cell carcinoma of the bladder treated relatively uniformly with preoperative radiotherapy (50 Gy in 25 fractions) 4 to 6 weeks prior to radical cystectomy.

METHODS

Adequate formalin-fixed paraffin-embedded archival tissue for the immunohistochemical staining of p53 using antibody DO1 was obtained in 109 patients. The median follow-up for those living was 91 months.

RESULTS

Overall, p53 staining was positive in 56% of the cases, with 60% positive in Stage T2 (n = 48), 42% in Stage T3a (n = 31), and 63% in Stage T3b (n = 30). Overexpression of p53 did not correlate with actuarial local control, distant metastasis freedom, disease freedom, or overall survival. However, significant associations were seen when these analyses were limited to patients with clinical Stage T3b disease. In this subgroup, the actuarial 5-year rates for patients with p53 positively and negatively stained tumors were 55% and 100%, respectively, for distant metastasis freedom (P = 0.01), 51% and 91% for disease freedom (P = 0.04), and 32% and 91% for overall survival (P = 0.006). Cox proportional hazards models that included p53 staining and other prognostic factors of significance in the univariate analyses revealed p53 to be independently predictive of survival for patients with Stage T3b disease.

CONCLUSIONS

The prognostic value of p53 immunostaining rested with Stage T3b patients. Although no correlations were found with radiation response, p53 positivity in this subgroup was associated with a higher rate of distant metastasis and reduced overall survival. For these patients, p53 negativity would indicate that aggressive local treatment (that is, preoperative radiotherapy and cystectomy) is sufficient, whereas p53 positivity would indicate that multiagent chemotherapy is required because of the increased risk of distant metastasis.