p53 and c-myc expression in stage A1 prostatic adenocarcinoma: useful prognostic determinants?

Leelamine suppresses cMyc expression in prostate cancer cells in vitro and inhibits prostate carcinogenesis in vivo

Aim

Leelamine (LLM) inhibits growth of human prostate cancer cells but the underlying mechanism is not fully understood. The present study was undertaken to determine the effect of LLM on cMyc, which is overexpressed in a subset of human prostate cancers.

Methods

The effect of LLM on cMyc expression and activity was determined by western blotting/confocal microscopy and luciferase reporter assay, respectively. A transgenic mouse model of prostate cancer (Hi-Myc) was used to determine chemopreventive efficacy of LLM.

Results

Exposure of androgen sensitive (LNCaP) and castration-resistant (22Rv1) human prostate cancer cells to LLM resulted in downregulation of protein and mRNA levels of cMyc. Overexpression of cMyc partially attenuated LLM-mediated inhibition of colony formation, cell viability, and cell migration in 22Rv1 and/or PC-3 cells. LLM treatment decreased protein levels of cMyc targets (e.g., lactate dehydrogenase), however, overexpression of cMyc did not attenuate these effects. A trend for a decrease in expression level of cMyc protein was discernible in 22Rv1 xenografts from LLM-treated mice compared with control mice. The LLM treatment (10 mg/kg body weight, 5 times/week) was well-tolerated by Hi-Myc transgenic mice. The incidence of high-grade prostatic intraepithelial neoplasia, adenocarcinoma in situ, and microinvasion was lower in LLM-treated Hi-Myc mice but the difference was not statistically significant.

Conclusion

The present study reveals that LLM inhibits cMyc expression in human prostate cancer cells in vitro but concentrations higher than 10 mg/kg may be required to achieve chemoprevention of prostate cancer.

A novel metabolic function of Myc in regulation of fatty acid synthesis in prostate cancer

A subset of human prostate cancer exhibits increased de novo synthesis of fatty acids, but the molecular driver(s) of this metabolic abnormality remains obscure. This study demonstrates a novel metabolic function of c-Myc (Myc) in regulation of fatty acid synthesis. The role of Myc in regulation of fatty acid synthesis was investigated by: (a) interrogation of the prostate cancer The Cancer Genome Atlas (TCGA) dataset, (b) chromatin immunoprecipitation, and (c) determination of the expression of fatty acid synthesis enzymes and targeted metabolomics using a mouse model and human specimens. The expression of MYC was positively associated with that of key fatty acid synthesis genes including ACLY, ACC1, and FASN in prostate cancer TCGA dataset. Chromatin immunoprecipitation revealed Myc occupancy at the promoters of ACLY, ACC1, and FASN. Prostate-specific overexpression of Myc in Hi-Myc transgenic mice resulted in overexpression of ACLY, ACC1, and FASN proteins in neoplastic lesions and increased circulating levels of total free fatty acids. Targeted metabolomics confirmed increased circulating levels of individual fatty acids in the plasma of Hi-Myc mice and human subjects when compared to corresponding controls. Immunohistochemistry also revealed a positive and statistically significant association in expression of Myc with that of ACC1 in human prostate adenocarcinoma specimens. We propose that Myc-regulated fatty acid synthesis is a valid target for therapy and/or prevention of prostate cancer.

Super-resolution imaging reveals the evolution of higher-order chromatin folding in early carcinogenesis

Genomic DNA is folded into a higher-order structure that regulates transcription and maintains genomic stability. Although progress has been made on understanding biochemical characteristics of epigenetic modifications in cancer, the in-situ higher-order folding of chromatin structure during malignant transformation remains largely unknown. Here, using optimized stochastic optical reconstruction microscopy (STORM) for pathological tissue (PathSTORM), we uncover a gradual decompaction and fragmentation of higher-order chromatin folding throughout all stages of carcinogenesis in multiple tumor types, and prior to tumor formation. Our integrated imaging, genomic, and transcriptomic analyses reveal functional consequences in enhanced transcription activities and impaired genomic stability. We also demonstrate the potential of imaging higher-order chromatin disruption to detect high-risk precursors that cannot be distinguished by conventional pathology. Taken together, our findings reveal gradual decompaction and fragmentation of higher-order chromatin structure as an enabling characteristic in early carcinogenesis to facilitate malignant transformation, which may improve cancer diagnosis, risk stratification, and prevention.

MYC Overexpression at the Protein and mRNA Level and Cancer Outcomes among Men Treated with Radical Prostatectomy for Prostate Cancer

Background: The proto-oncogene MYC is implicated in prostate cancer progression. Whether MYC tumor expression at the protein or mRNA level is associated with poorer prognosis has not been well studied.Methods: We conducted a cohort study including 634 men from the Physicians' Health Study and Health Professionals Follow-up Study treated with radical prostatectomy for prostate cancer in 1983-2004 and followed up for a median of 13.7 years. MYC protein expression was evaluated using IHC, and we used Cox regression to calculate HRs and 95% confidence intervals (CIs) of its association with lethal prostate cancer (distant metastases/prostate cancer-related death). We assessed the association between MYC mRNA expression and lethal prostate cancer in a case-control study, including 113 lethal cases and 291 indolent controls.Results: MYC nuclear protein expression was present in 97% of tumors. MYC protein expression was positively correlated with tumor proliferation rate (r = 0.37; P < 0.001) and negatively correlated with apoptotic count (r = -0.17; P < 0.001). There were no significant associations between MYC protein expression and stage, grade, or PSA level at diagnosis. The multivariable HR for lethal prostate cancer among men in the top versus bottom quartile of MYC protein expression was 1.09 (95% CI, 0.50-2.35). There was no significant association between MYC mRNA expression and lethal prostate cancer.Conclusions: Neither MYC protein overexpression nor MYC mRNA overexpression are strong prognostic markers in men treated with radical prostatectomy for prostate cancer.Impact: This is the largest study to examine the prognostic role of MYC protein and mRNA expression in prostate cancer. Cancer Epidemiol Biomarkers Prev; 27(2); 201-7. ©2017 AACR.

Genetic alterations in benign prostatic hyperplasia patients

Background: Benign prostate hyperplasia (BPH) is a classical age-related disease of the prostate, present in 20% of men at the age of 40 years with progression to 70% by the age of 60 years. BPH is associated with various lower urinary tract symptoms, which affect their day-to-day life.

Materials and methods: Our objective was to evaluate the association between HER-2/neu, c-myc, p53, and clinicopathological variables in 45 patients diagnosed with benign prostatic hyperplasia using fluorescence in situ hybridization (FISH). The patients underwent transurethral prostate resection to address their primary urological problem. All patients were evaluated by use of a comprehensive medical history and rectal digital examination. The preoperative evaluation also included serum prostate specific antigen (PSA) measurement and ultrasonographic measurement of prostate volume.

Results: The mean (± standard deviation) age of the 45 patients was 69.65 ± 8.97 years. The mean PSA value of the patients was 9.25 ± 5.12 ng/mL. The mean prostate volume was 65.46 ± 11.43 mL. Amplification of HER-2/neu was seen in 4/45 (8.9%) cases and amplification of c-myc was seen in 5 of 45 (11.1%) cases; both genes were not associated with adverse clinicopathological variables. Deletion of p53 was seen in 20/45 (44.4%) cases. p53 gene was significantly associated with a severe AUASI (American Urological Association Symptom Index) score.

Conclusion: In this study, we discussed important genetic markers in benign prostatic hyperplasia patients which may, in the future, be used as markers for diagnosis and prognosis, as well as targets for therapeutic intervention.

Effects of alcohol on c-Myc protein in the brain

Alcoholism is a disorder categorized by significant impairment that is directly related to persistent and extreme use of alcohol. The effects of alcoholism on c-Myc protein expression in the brain have been scarcely studied. This is the first study to investigate the role different characteristics of alcoholism have on c-Myc protein in the brain. We analyzed c-Myc protein in the hypothalamus and amygdala from five different animal models of alcohol abuse. c-Myc protein was increased following acute ethanol exposure in a mouse knockout model and following chronic ethanol consumption in vervet monkeys. We also observed increases in c-Myc protein exposure in animals that are genetically predisposed to alcohol and methamphetamine abuse. Lastly, c-Myc protein was increased in animals that were acutely exposed to methamphetamine when compared to control treated animals. These results suggest that in substance abuse c-Myc plays an important role in the brain's response.

MYC and Prostate Cancer

Prostate cancer, the majority of which is adenocarcinoma, is the most common epithelial cancer affecting a majority of elderly men in Western nations. Its manifestation, however, varies from clinically asymptomatic insidious neoplasms that progress slowly and do not threaten life to one that is highly aggressive with a propensity for metastatic spread and lethality if not treated in time. A number of somatic genetic and epigenetic alterations occur in prostate cancer cells. Some of these changes, such as loss of the tumor suppressors PTEN and p53, are linked to disease progression. Others, such as ETS gene fusions, appear to be linked more with early phases of the disease, such as invasion. Alterations in chromosome 8q24 in the region of MYC have also been linked to disease aggressiveness for many years. However, a number of recent studies in human tissues have indicated that MYC appears to be activated at the earliest phases of prostate cancer (e.g., in tumor-initiating cells) in prostatic intraepithelial neoplasia, a key precursor lesion to invasive prostatic adenocarcinoma. The initiation and early progression of prostate cancer can be recapitulated in genetically engineered mouse models, permitting a richer understanding of the cause and effects of loss of tumor suppressors and activation of MYC. The combination of studies using human tissues and mouse models paints an emerging molecular picture of prostate cancer development and early progression. This picture reveals that MYC contributes to disease initiation and progression by stimulating an embryonic stem cell-like signature characterized by an enrichment of genes involved in ribosome biogenesis and by repressing differentiation. These insights pave the way to potential novel therapeutic concepts based on MYC biology.

Overexpression of C-MYC oncogene in prostate cancer predicts biochemical recurrence

Alterations of chromosome 8, including amplification at 8q24 harboring the C-MYC oncogene, have been noted as one of the most common chromosomal abnormalities in prostate cancer (CaP) progression. However, the frequency of C-MYC alterations in CaP has remained uncertain. A recent study, using a new anti-MYC antibody, described prevalent upregulation of nuclear C-MYC protein expression as an early oncogenic alteration in CaP. Further, we have recently reported regulation of C-MYC expression by ERG and a significant correlation between C-MYC overexpression and TMPRSS2-ERG fusion in early stage CaP. These emerging data suggest that increased C-MYC expression may be a critical and early oncogenic event driving CaP progression. In this study, we assessed whether C-MYC mRNA overexpression in primary prostate tumors was predictive of more aggressive tumor or disease progression. Our approach was to quantitatively determine C-MYC mRNA expression levels in laser capture micro-dissected tumor cells and matched benign epithelial cells in a radical prostatectomy cohort with long follow-up data available. On the basis of our results, we conclude that elevated C-MYC expression in primary prostate tumor is biologically relevant and may be a predictor of future biochemical recurrence.

Role of immunohistochemistry and apoptosis as investigative tools in assessing the prognosis of patients with prostate tumours

Apoptosis is a form of programmed cell death necessary for the regulation of the size of organs in adult life. Disruption of apoptotic pathways has been suggested as an important regulatory mechanism in prostatic tumours. The aim of this study was to examine the expression of apoptosis-regulating genes bcl-2 and p53 using immunohistochemistry, and the Gleason score in core needle biopsy specimens of prostate adenocarcinoma. We studied bcl-2 and p53 expression in 30 cases of low-, 30 cases of intermediate- and 20 cases of high-grade prostate adenocarcinoma. Overexpression of bcl-2 and p53 were noted in 54 and 61 of 80 patients (67.5 and 76.25%), respectively. The statistical analysis of the present data suggested that there is significant relation between p53 and bcl-2 expression, and Gleason score in prostate cancer. Thus, immunohistochemistry is a useful investigative parameter in assessing apoptosis to analyse the prognosis of prostatic tumours.

Nuclear MYC protein overexpression is an early alteration in human prostate carcinogenesis

The MYC onco-protein is a transcription factor that regulates cell proliferation, metabolism, protein synthesis, mitochondrial function and stem cell renewal. A region on chromosome 8q24 encompassing the MYC locus is amplified in prostate cancer, but this occurs mostly in advanced disease suggesting that MYC alterations occur late in prostate cancer. In contrast, MYC mRNA is elevated in most prostate cancers, even those of relatively low stage and grade (eg Gleason score 6) suggesting that MYC plays a role in initiation. However, since MYC protein levels are tightly regulated, elevated MYC mRNA does not necessarily imply elevated MYC protein. Thus, it is critical to determine whether MYC protein is elevated in human prostate cancer, and if so, at what stage of the disease this elevation occurs. Prior studies of MYC protein localization have been hampered by lack of suitable antibodies and controls. We utilized a new anti-MYC antibody coupled with genetically defined control experiments to localize MYC protein within human tissue microarrays consisting of normal, atrophy, PIN, primary adenocarcinoma, and metastatic adenocarcinoma. Nuclear overexpression of MYC protein occurred frequently in luminal cells of PIN, as well as in most primary carcinomas and metastatic disease. MYC protein did not correlate with gain of 8q24, suggesting alternative mechanisms for MYC overexpression. These results provide evidence that upregulation of nuclear MYC protein expression is a highly prevalent and early change in prostate cancer and suggest that increased nuclear MYC may be a critical oncogenic event driving human prostate cancer initiation and progression.

Prognostic Value of DNA Ploidy, bcl-2 and p53 in Localized Prostate Adenocarcinoma Incidentally Discovered at Transurethral Prostatectomy

PURPOSE

Discovery of prostatic adenocarcinoma limited to transurethral resection material generates a treatment dilemma. We investigated the usefulness of parameters shown to be associated with prognosis in prostate cancer (p53 and bcl-2 immuno-expression, DNA cell cycle analysis and Gleason score) to stratify these incidentally identified tumors to guide clinical decision making.

MATERIALS AND METHODS

Paraffin embedded tissues from transurethral prostate resection specimens containing T1a prostate adenocarcinoma from 44 patients who underwent resection between 1980 and 1990 were immunostained for p53 and bcl-2, and subjected to flow cytometry to determine DNA ploidy. Gleason score was determined by 2 pathologists independently. Statistical relationships among these 4 variables, tumor progression and cancer specific survival were analyzed.

RESULTS

Six of 44 patients in the study population had cancer progression. Time to clinical progression was 4.5 years (range 7 months to 11 years). Most tumors stained negative for p53 and bcl-2. Only 2 tumors studied were aneuploid and neither of these 2 patients had cancer progression. Only Gleason score was a significant predictor of cancer progression on univariate and multivariate Cox regression analysis (p = 0.045 and 0.046, respectively). No tumor characteristics correlated with time to disease progression, including p53 and bcl-2 immuno-expression, and Gleason score (p = 0.182, 0.563 and 0.346, respectively). Positive immunostaining for p53 and bcl-2 did not occur together in the same tumor in significant fashion (p = 0.334), nor did either significantly occur more with aneuploidy (p = 0.237 and 0.307 respectively).

CONCLUSIONS

For T1a prostate cancer incidentally detected on transurethral prostate resection p53 and bcl-2 immuno-expression, and DNA ploidy do not predict survival or disease progression.

Molecular markers in the diagnosis of prostate cancer

The genetic alterations leading to prostate cancer are gradually being discovered. A wide variety of genes have been associated with prostate cancer development as well as tumor progression. Knowledge of gene polymorphisms associated with disease aid in the understanding of important pathways involved in this process and may result in the near future in clinical applications. Urinary molecular markers will soon be available to aid in the decision of repeat prostate biopsies. Recent findings suggest the importance of androgen signaling in disease development and progression. The further understanding of interaction of inflammation, diet, and genetic predisposition will improve risk stratification in the near future.

Genetic alterations in prostate cancer

Prostate cancer is the most common nondermatologic malignancy in men. Prostate cancer is characterized by clinical and biologic heterogeneity that has complicated molecular and epidemiologic studies. Like other epithelial malignancies, prostate tumors exhibit complex karyotypic abnormalities and harbor many specific genetic alterations. Although recent work has begun to elucidate many of the specific mutations associated with prostate cancer, we still lack a clear understanding of the complement of genetic changes that suffice to program the malignant state. Here, we review our current understanding of the genetic changes found in prostate cancer and explore the connections between specific genetic alterations and malignant phenotypes including cell growth, survival, invasion, and metastasis.

Molecular markers of prostate cancer outcome

Molecular markers have the potential to serve not only as prognostic factors but may be targets for new therapeutic strategies and predictors of response in a range of cancers. Prostate cancer development and progression is predicated on a series of genetic and epigenetic events within the prostate cell and its milieu. Within this review, we identify candidate molecules involved in diverse processes such as cell proliferation, death and apoptosis, signal transduction, androgen receptor (AR) signalling, cellular adhesion and angiogenesis that are linked to outcome in prostate cancer. Current markers with potential prognostic value include p53, Bcl-2, p16INK4A, p27Kip1, c-Myc, AR, E-cadherin and vascular endothelial growth factor. Evolving technology permits the identification of an increasing number of molecular markers with prognosis and predictive potential. We also review the use of gene microarray analysis in gene discovery as a means of identifying and cosegregating novel markers of prostate cancer outcome. By integrating selected markers into prospective clinical trials, there is potential for us to provide specific targeted therapy tailored for an increasing number of patients.

Molecular biology of prostate cancer

Development of any cancer reflects a progressive accumulation of alterations in various genes. Oncogenes, tumour suppressor genes, DNA repair genes and metastasis suppressor genes have been investigated in prostate cancer. Here, we review current understanding of the molecular biology of prostate cancer. Detailed understanding of the molecular basis of prostate cancer will provide insights into the aetiology and prognosis of the disease, and suggest avenues for therapeutic intervention in the future.

Relationship between apoptosis regulator proteins (bcl-2 and p53) and Gleason score in prostate cancer

Cellular proliferation programmed cell death (apoptosis) are associated with tumor growth in general, and prostate cancer growth in particular. The aim of this study was to examine the expression of the apoptosis regulating genes bcl-2 and p53 and Gleason score in core needle biopsy specimens of prostate cancer using immunohistochemistry. We studied bcl-2 and p53 expression in 12 cases of low grade (Gleason score 2-5), 12 cases of intermediate grade (Gleason score 6-7) and 8 cases of high grade (Gleason score 8-10) prostate cancer. Overexpression of bcl-2 was noted in 3 of 32 patients (9.32%). One of them was high grade; others were intermediate grades. Expression of p53 was observed in 3 of low grades; others were high grade. The statistical analysis of present data suggest that there is no significant relation between p53 and bcl-2 expression and Gleason score in prostate cancer.

Mxi1, a Myc antagonist, suppresses proliferation of DU145 human prostate cells

BACKGROUND

Mxi1, an antagonist of c-Myc, maps to human chromosome 10q24-q25, a region altered in a substantial fraction of prostate tumors. Mice deficient for Mxi1 exhibit significant prostate hyperplasia. We studied the ability of Mxi1 to act as a growth suppressor in prostate tumor cells.

METHODS

We infected DU145 prostate carcinoma cells with an Mxi1-expressing adenovirus (AdMxi1) in vitro, and measured Mxi1 expression, cell proliferation, soft agar colony formation, and cell cycle distribution. To explore mechanisms of Mxi1-induced growth arrest, we performed gene expression analysis.

RESULTS

AdMxi1 infection resulted in reduced cell proliferation, reduced soft agar colony formation, and a higher proportion of cells in the G(2)/M phase of the cell cycle. This G(2)/M growth arrest was associated with elevated levels of cyclin B, and reduced levels of c-MYC and MDM2.

CONCLUSIONS

The ability of AdMxi1 to suppress prostate tumor cell proliferation supports a role for Mxi1 loss in the pathogenesis of a subset of human prostate cancers. Prostate 47:194-204, 2001.

Mutations within the tumour suppressor gene p53 are not confined to a late event in prostate cancer progression. a review of the evidence

Mutations in the p53 tumour suppressor gene are generally believed to be a late event in the progression of prostate cancer, and are associated with androgen independence, metastasis, and a worse prognosis. In this review, we examine the current literature available on p53 mutations and focus on stages A (T1) and B (T2) of prostate cancer. We report here that p53 mutations can be found in approximately one third of prostate cancers that are clinically localized to the prostate. In addition, high levels of p53 mutation are found in normal prostate tissue of prostate cancer patients, prostatic intraepithelial neoplasia, and benign prostatic hyperplasia. The limitations of techniques used to determine p53 mutations are discussed, as well as other modes of p53 loss in early stage prostate cancer.

p53 tumor suppressor gene mutations in transformed cutaneous T-cell lymphoma: a study of 12 cases

The transformation of cutaneous T-cell lymphoma (t-CTCL) is an uncommon phenomenon that is associated with histopathologic changes and follows an aggressive course. The factors contributing to this transformation are poorly understood. The aim of this study was to analyze the p53 status in t-CTCL and to correlate it with disease outcome. The p53 status was investigated by immunohistochemistry, single-strand conformation polymorphism (SSCP) and DNA sequencing in 12 patients with t-CTCL. Eight mutations were detected; including four in exon 5, one in exon 6 and three in exon 7. Five were point mutations and three were deletions. Paired samples from nontransformed patch and plaque lesions showed no p53 over-expression. Eight disease-related deaths were reported, six to 23 months after transformation, all of which had p53 mutations. Three other patients with wild phenotype (WT-p53) were last reported alive with the disease 19-33 months after transformation (p < 0.0002). One other case had a p53 mutation but a short period of follow-up. Our results suggest that phenotypic changes of t-CTCL are frequently associated with genotype alterations in the p53 gene. Because 70% of the mutations detected were either G to C transversions or deletions, nucleotide-pairing mismatch and not DNA damage by UVB represents a likely mechanism for mutagenesis. Furthermore, the data may help in the design of gene transfer therapies that target the p53 molecule.

An evaluation of the markers p53 and Ki-67 for their predictive value in prostate cancer

BACKGROUND AND OBJECTIVES

p53 and Ki-67 are but two markers being evaluated for their predictive value in prostate cancer. The purpose of this study was to compare p53 and Ki-67 with age, stage, Gleason score, and ploidy for their prognostic abilities in prostate cancer.

METHODS

Prostate cancer specimens from 134 patients were immunohistochemically stained for p53 and Ki-67 expression and differences evaluated by SPSS analysis of variance (ANOVA) methods. The dependent variable was patient survival and the independent variables were age, stage, Gleason score, and ploidy.

RESULTS

In decreasing order of prediction of survival were stage (P < 0.001), Gleason score (P < 0.001), age (P = 0.1869), Ki-67 (P = 0.2284), p53 (P = 0.4282) and ploidy (P = 0.8141).

CONCLUSION

It is concluded that stage and Gleason score are significant predictors of survival while p53, Ki-67, age and ploidy are not.

Assessment of the biologic markers p53, Ki-67, and apoptotic index as predictive indicators of prostate carcinoma recurrence after surgery

BACKGROUND

This study was designed to evaluate the potential of the molecular and cellular markers p53, Ki-67, and apoptotic index (AI) as adjuncts to the commonly available variables of tumor grade, clinical stage, and serum prostate specific antigen to predict prostate carcinoma recurrence after radical prostatectomy.

METHODS

Representative punch biopsy specimens of prostate carcinoma from whole mount paraffin blocks were evaluated from 47 men who underwent radical prostatectomy. Two groups were defined: those without evidence of prostate carcinoma recurrence after 5 years of follow-up (N = 30) and those with carcinoma recurrence (N = 17). Gleason grade, clustered p53 immunostaining, Ki-67 immunostaining, and AI were determined by standard techniques.

RESULTS

All variables tested were associated with disease recurrence by univariate analysis: AI (P = 0.005), clustered p53 immunostaining (P = 0.0070), and Ki-67 immunostaining (P = 0.0390). Using multivariate analyses that included each biomarker with routinely available features, only AI (P = 0.0234) and clustered p53 immunostaining (P = 0.0389) added independent prognostic information (Ki-67 immunostaining, P = 0.1285). In the final logistic regression model that included standard variables with AI and p53, only AI reached statistical significance (P = 0.0332).

CONCLUSIONS

The continued assessment of additional biomarkers for prostate carcinoma recurrence is important to identify better those patients who may be candidates for early adjuvant therapy and also to further our understanding of the neoplastic potential of a particular malignancy.

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 markers of intravesical bacillus Calmette-Guérin therapy for multiple, high-grade, stage T1 bladder cancers

BACKGROUND

Prediction of a response to intravesical bacillus Calmette-Guérin (BCG) therapy for bladder cancer is clinically important. We determined whether several molecular markers have prognostic value in intravesical BCG therapy for multiple, high-grade, stage T1 bladder cancers.

METHODS

The expressions of p53 (clone D07), bcl-2 (100-D5), cathepsin-D (C5), c-myc(9E11), c-erbB-2 (CB11) and Ki-67 (MM1) were determined by immunohistochemistry in paraffin-embedded tissues from 32 multiple, T1, grade II-III bladder cancer patients (15 BCG responders, 17 nonresponders) who had undergone a single course of BCG therapy (Pasteur strain, 5 x 10(8) CFU weekly for 6 weeks) after complete removal of the tumors. The association between the expression of these markers and the response to BCG was assessed by univariate and multivariate analyses.

RESULTS

There was no difference in patient and tumor characteristics between the 2 groups. Using multivariate analysis, the only useful marker was p53, with the overexpression of the p53 protein inversely related to the response to BCG therapy (P = 0.0182).

CONCLUSION

Our results suggest that the status of p53 expression offers significant clinical information and may be a useful tool in the selection of suitable candidates for BCG therapy in multiple, high-grade stage T1 bladder cancer patients.

The relationship between prostatic intraepithelial neoplasia and prostate cancer: critical issues

PURPOSE

Prostatic intraepithelial neoplasia (PIN) is often considered to be a premalignant lesion and the main precursor of invasive carcinoma of the prostate. We evaluated the evidence for and against PIN as a premalignant lesion and determined guidelines for the clinical management of PIN.

MATERIALS AND METHODS

Literature analysis of histopathological, morphometric, phenotypic and molecular genetic evidence of progression and of clinical findings regarding PIN was done. Literature searches were performed on MEDLINE with relevant key words.

RESULTS

PIN, like prostate cancer, occurs most frequently in the peripheral zone of the prostate and is usually located in close proximity to prostate cancer. The relative PIN and prostate cancer volumes vary inversely. Prostate specific antigen in cases of PIN appears to be intermediate between prostate cancer and normal levels, although this elevation may be explained by concomitant prostate cancer or benign prostatic hyperplasia. Deoxyribonucleic acid ploidy in PIN follows the aneuploid proportion as in the concomitant prostate cancer. Prostate cancer and PIN show evidence of loss of putative tumor suppressor genes on chromosome 8p. The clinical relevance of PIN biopsy findings is based on the association of neoplasia and prostate cancer. High grade PIN in core biopsies without concomitant prostate cancer has a substantial risk for prostate cancer in subsequent biopsies (24 to 73%, up to 100% when the digital rectal examination is suspicious) and should cause further biopsy sampling.

CONCLUSIONS

There is convincing evidence that PIN is a precursor lesion to prostate cancer, with a close association of PIN and prostate cancer in biopsy and prostatectomy specimens. A biopsy finding of high grade PIN necessitates further investigation in patients who are candidates for radical treatment for localized prostate cancer.

Expression of oncoproteins and the amount of eosinophilic and lymphocytic infiltrates can be used as prognostic factors in gastric cancer. Dutch Gastric Cancer Group (DGCG)

Preoperative staging of gastric cancer is difficult. Several molecular markers associated with initiation and progression of cancer seem promising for obtaining preoperative prognostic information. To investigate whether these markers are indicative especially for the presence of lymph node metastases in patients with gastric cancer, we have examined primary tumour specimens from 105 patients with primary adenocarcinoma of the stomach entered in a surgical trial. In this trial, lymph node status was determined by strictly quality-controlled lymph node dissection and examination. The selected markers were growth regulators (p53, Rb and myc), metastasis-suppressor gene product (nm23), adhesion molecules (Ep-CAM, E-cadherin, CD44v5 and CD44v6) and urokinase-type plasminogen activator (u-PA). Also, the amount of eosinophilic and lymphocytic infiltrates available post-operatively was analysed with respect to its prognostic value for lymph node status. Moreover, the association of these parameters with survival and disease-free period (DFP) was evaluated. Of all molecular markers investigated, only Rb expression had a significant association with the presence of lymph node metastasis in both univariate and multivariate analysis. For curative resectability, a significant association was found with Rb and E-cadherin expression, while in multivariate analysis Rb and myc were selected as the combination with additional independent prognostic value, and E-cadherin had no additional independent value. For overall survival in univariate analysis, the amount of both eosinophilic and lymphocytic infiltrates and Rb and myc expression were of significant prognostic value. Only the amount of lymphocytic infiltrate had a prognostic significance for DFP. In stepwise multivariate analysis, TNM stage (I + II) and marked lymphocytic infiltrate were associated with better overall survival and longer DFP. We conclude that, if these results are confirmed in a larger series of patients, molecular markers can provide useful prognostic information.

Correlation of genetic and immunodetection of TP53 mutations in malignant and benign prostate tissues

The prognostic value of the p53 gene (TP53), the most commonly mutated gene in human cancers, has been well established for several cancer types. However, because varying frequencies of TP53 mutations have been identified in prostatic adenocarcinoma (CaP) by genetic and immunohistochemical (IHC) studies, the role of TP53 in CaP tumorigenesis is currently unresolved. These experimental discrepancies could be caused by tissue heterogeneity within prostatic neoplasms, variations in experimental protocols, or other factors. Thus, the goal of this study was to develop a reliable IHC approach for the detection of p53 in archival prostate tissue. The authors evaluated four p53 antibodies, CM-1, 1801, DO-1, and DO-7, for their ability to reveal p53. They chose two reference CaP cell lines, 26 patient specimens (including eight benign prostatic hyperplasias (BPHs), 16 CaPs, and two lymph node metastases), one prostate and nine kidney cell lines for p53 analysis. The TP53 status of these samples was characterized using single-strand conformational polymorphism (SSCP) analysis of RNA/PCR products and sequencing. IHC detection of p53 was markedly enhanced by using the combination of microwave heat-induced antigen unmasking and a cocktail of the DO-1 and DO-7 antibodies. This approach identified 14 of 15 (93%) cell lines and patient samples having TP53 missense mutations in the exons 5 to 8 region. Of the 21 patient samples and cell lines that were either normal by SSCP or expressed p53 mutations that are not expected to stain, 18 (86%) were immunonegative. Because of this good correlation between molecular and IHC analysis, this approach may help to resolve the uncertainty about TP53 in CaP tumorigenesis.

A new minimally invasive open pelvic lymphadenectomy surgical technique for the staging of prostate cancer

We report a new method for lymphadenectomy, the minilaparotomy (inguinal) pelvic lymph node dissection (MLPLND), and compare it with laparoscopic pelvic lymph node dissection (LPLND) in terms of cost, effectiveness, operation time and morbidity. We reviewed a series of 111 consecutive patients: 51 had MLPLND and 60 had LPLND. All patients had proved adenocarcinoma of the prostate by biopsy. Of the MLPLND patients, only 1 had to stay overnight in the hospital, and all left within 24 hours. Pelvic lymphadenectomy consisted of nodal removal along the internal iliac vessels and the external iliac vein, and nodes of the obturator foramen. A total of 14% of the patients had disease involving the lymph nodes. The cost of MLPLND was 50% of the cost of LPLND, with no interoperative or postoperative morbidity. This new operation can be performed thoroughly an inexpensively in approximately 35 minutes, with little or no morbidity. Since the drawbacks of laparoscopic techniques associated with instrument costs and the learning curve for this technically difficult operation are eliminated, staging pelvic lymphadenectomy can be performed routinely on a wider variety of patients with potential metastatic disease. Currently, we recommend MLPLND to any patient with a tumor of Gleason score 7 or higher or a serum prostate-specific antigen value of 15 ng/mL or higher.

Prostatic carcinoma: Study of C-erb B2, p53, morphological and clinical parameters in 44 radical prostatectomies

In literature it is estimated that only 20% of prostatic carcinoma are clinically important and indicators of biological aggressiveness of the neoplasm would therefore seem necessary. We considered 44 radical prostatectomies that were performed in our Division between 1989 and 1996. A histological section was selected for each patient on which the expression of C-erb B2 and p53 were tested with immunohistochemical methods. In these patients, who were homogeneous as far as surgical criteria are concerned, no subgroups with different progression were found.

p53 protein expression as prognostic factor in patients undergoing radical prostatectomy for prostatic cancer

The authors give preliminary data on the evaluation of the p53 protein expression as prognostic factor in patients subjected to radical prostatectomy for prostatic cancer. p53 protein immunohistochemical nuclear staining was carried out on neoplastic tissue obtained from systematic sextant prostatic biopsies at the time of diagnosis. Out of 46 Patients 15 (32%) were p53 positive (p53+). No statistical correlation was observed between P53 staining, preoperative PSA and pathological Gleason Score, while the rate of patients with nodal involvement (pN+) was higher in the p53+ group than the P53- group with low statistical significance (p<0.03). The authors cannot yet evaluate Progression time and survival because the mean follow-up of the patients is still too short (30 months). The study is still in progress.

Immunoreactive p53 protein in high-grade prostatic intraepithelial neoplasia

p53 protein accumulation in the nuclei of prostatic carcinoma cells, as detected by immunohistochemistry, has been associated with increased cell proliferation rate, increased histologic grade and stage, androgen independence and decreased patient survival. Little is known, however, of p53 in prostatic intraepithelial neoplasia (PIN), the putative precursor proliferation for moderately to poorly differentiated peripheral zone carcinoma of the prostate. In this investigation, we utilized a panel of antibodies reactive with p53 protein to assess p53 protein accumulation in prostatic epithelial hyperplasia, PIN and prostatic carcinoma. Forty patients who had undergone radical prostatectomy were selected for study based on the presence of high grade PIN and carcinoma in the same prostate tissue block. Tissue sections were treated with microwave irradiation for antigen retrieval, and antibodies DO-7, PAb1801 and CM-1 were used for immunohistochemical analysis. An intense signal for immunoreactive p53 was identified in the nuclei of 7/40 (17.5%) clinically-localized prostatic carcinomas. In all 7 cases, high grade PIN also exhibited intense p53 immunoreactivity, whereas only one case of hyperplasia contained immunoreactive p53 protein. These findings support a close relationship between high grade PIN and carcinoma in a subset of primary prostatic carcinomas with high-level p53 protein accumulation.

Progression to androgen insensitivity in a novel in vitro mouse model for prostate cancer

We have shown previously that the ras and myc oncogenes can induce poorly differentiated mouse prostate carcinomas in vivo with high frequency (greater than 90%) using inbred C57BL/6 mice in the mouse prostate reconstitution model system. To study the androgen sensitivity of these carcinomas, we have developed an in vitro model system which includes a cell line from normal urogenital sinus epithelium (CUGE) and cell lines from three ras + myc transformed mouse prostate carcinomas (RM-9, RM-1, and RM-2). CUGE cells, as well as all prostate carcinoma cell lines, were positive for cytokeratin 18 mRNA and immunoreactive to cytokeratin-specific antiserum. Two out of three of the early passage carcinoma cell lines were clonal with respect to Zipras/myc 9 retrovirus integration as determined by Southern blot analysis. Whereas significant mitogenic effects of testosterone (10 nM) were not seen in CUGE cells grown in serum-free medium, under similar conditions approx. 2-fold increases in cell number were seen in all low passage prostate carcinoma cell lines. Also, in the presence of growth inhibitory levels of suramin (50 micrograms/ml), testosterone was capable of significant growth stimulation in the carcinoma cell lines. With further propagation from low passage [20-25 population doublings (PD)] to high passage (75-100 PD), all carcinoma cell lines demonstrated increased and similar growth rate in the presence and absence of testosterone. These cell lines maintained stable androgen receptor numbers and binding kinetics during the transition from testosterone-responsive growth to reduced responsivity over multiple passages in culture (> 150 PD). Overall, our studies indicate that the capacity to bind testosterone is stably maintained through the transition of the androgen-sensitive to insensitive phenotype and raise the possibility that androgen sensitivity can persist throughout progression but is masked by the acquisition of autocrine pathways.

Immunohistochemical detection of p53 protein as a prognostic indicator in prostate cancer

Mutation of the p53 gene is the most common genetic alteration in human cancers. The mutant p53 protein is more stable than the wild type and can be detected by immunohistology. The objective of the current study was to evaluate the immunohistological detection of p53 protein in prostate cancer and its utility as a prognostic indicator. We used a monoclonal anti-p53 antibody and immunostained primary prostate adenocarcinomas (stages A1 to D1) from 109 patients with a mean follow-up of 3.8 years (range, 1.3 to 9.3 years). Immunoreactivity for p53 was seen in 23 cancers (21%). There were 12 instances of progression (14%) among the p53-negative cancers versus seven (30%) among the p53-positive group. Survival analysis using three univariate statistical tests showed that p53 reactivity (P < .03), Gleason score (P < .01), and stage (P < .05) had significant effects on time to progression of prostate cancer. Multivariate analyses showed that Gleason score was significant with all three tests; p53 reactivity was significant with the Wilcoxon test but only approached significance by the log rank and Cox tests. When the analyses included only patients with Gleason scores 2 to 7 (N = 94), univariate analyses showed that p53 reactivity was strongly related to progression of prostate cancer (P < .007). Stage also was significant (P < 0.04), but Gleason score was not. Multivariate analyses showed only p53 reactivity to be significant (P < .007). In conclusion, mutation of the p53 gene may be involved in prostate cancer carcinogenesis. p53 reactivity marks an aggressive subset of prostate cancer and appears to be an independent prognostic indicator that is particularly valuable among the low to intermediate grade cancers.

Mutant p53 oncogene expression in keratoacanthoma and squamous cell carcinoma

The tumour suppressor gene p53, located on the short arm of chromosome 17, encodes for a nuclear protein which regulates cell proliferation by inhibiting cells entering S-phase. p53 mutations are alleged to be the commonest genetic abnormality in human cancer. We studied mutant p53 oncoprotein expression, using PAb1801 monoclonal antibody immunohistochemistry, in 25 'ideal' keratoacanthomas and 26 well-, 19 moderately and 18 poorly differentiated squamous cell carcinomas of the skin. While there was a highly significant trend in the proportion of p53 oncoprotein-positive lesions from keratoacanthomas to poorly differentiated squamous cell carcinomas (chi 2 = 17.13, df = 1, exact P = 0.00003), p53 expression was inadequate for distinguishing keratoacanthoma from well-differentiated squamous cell carcinoma (chi 2 = 2.55, df = 1, exact P = 0.18; corresponding to a sensitivity of 0.84 and a specificity of only 0.36).