p53 Immunostaining guided laser capture microdissection (p53-LCM) defines the presence of p53 gene mutations in focal regions of primary prostate cancer positive for p53 protein

Investigating Intensity and Percentage of p53 Nuclear Expression in Prostate Cancer: Findings from a Cohort of U.S. Military Veterans

BACKGROUND

Next-generation sequencing has revealed TP53 alterations in localized prostate cancer (PCa), suggesting growing clinical potential for p53 immunohistochemistry (IHC). Prior research supports the use of IHC for the detection of p53 overexpression to predict the presence of TP53 alterations known to be associated with adverse outcomes. However, to reach a consensus definition of p53 overexpression in PCa, further insights are needed. This study aimed to compare two fundamental approaches of evaluating p53 expression across a variety of specimens regarding PCa progression.

METHODS

This study included 84 patients (75% self-identified as African American) diagnosed with PCa between 1996 and 2021 at the DC VA Medical Center. Representative sections of core biopsies, radical prostatectomies, transurethral prostate resections, and metastatic deposits were examined. p53 nuclear expression was scored according to the highest intensity observed (0, 1+, 2+, 3+) and the percentage (0%, <1%, 1-5%, >5%) of tumor cells expressing any level of intensity in the aggregate tumor area. All slides were reviewed by two independent pathologists. Pertinent clinical data were collected.

RESULTS

A total of 34 patients (40%) exhibited p53 nuclear expression, of which 18 (21%) showed the maximum (3+) intensity. The presence of maximum intensity, regardless of percentage, was found to be associated with Grade Group (p < 0.001), higher PSA at biopsy (p < 0.001), BCR (p < 0.001) and metastasis (p < 0.001). Importantly, maximum p53 intensity was identified only in patients who developed metastatic disease.

CONCLUSIONS

Maximum (3+) p53 nuclear intensity of any percentage is highly associated with disease progression in PCa, suggesting that optimal determination of p53 overexpression should incorporate intensity.

Focal p53 protein expression and lymphovascular invasion in primary prostate tumors predict metastatic progression

TP53 is one of the most frequently altered genes in prostate cancer. The precise assessment of its focal alterations in primary tumors by immunohistochemistry (IHC) has significantly enhanced its prognosis. p53 protein expression and lymphovascular invasion (LVI) were evaluated for predicting metastatic progression by IHC staining of representative whole-mounted prostate sections from a cohort of 189 radical prostatectomy patients with up to 20 years of clinical follow-up. Kaplan–Meier survival curves were used to examine time to distant metastasis (DM) as a function of p53 expression and LVI status. TP53 targeted sequencing was performed in ten tumors with the highest expression of p53 staining. Nearly half (49.8%) of prostate tumors examined showed focal p53 expression while 26.6% showed evidence of LVI. p53(+) tumors had higher pathologic T stage, Grade Group, Nuclear Grade, and more frequent LVI. p53 expression of > 5% and LVI, individually and jointly, are associated with poorer DM-free survival. TP53 mutations were detected in seven of ten tumors sequenced. Four tumors with the highest p53 expression harbored likely pathogenic or pathogenic mutations. High levels of p53 expression suggest the likelihood of pathogenic TP53 alterations and, together with LVI status, could enhance early prognostication of prostate cancer progression.

Prognostic Features of Biochemical Recurrence of Prostate Cancer Following Radical Prostatectomy Based on Multiparametric MRI and Immunohistochemistry Analysis of MRI-guided Biopsy Specimens

Background Although prostate MRI is routinely used for the detection and staging of localized prostate cancer, imaging-based assessment and targeted molecular sampling for risk stratification are an active area of research. Purpose To evaluate features of preoperative MRI and MRI-guided biopsy immunohistochemistry (IHC) findings associated with biochemical recurrence (BCR) of prostate cancer after surgery. Materials and Methods In this retrospective case-control study, patients underwent multiparametric MRI before MRI-guided biopsy followed by radical prostatectomy between 2008 and 2016. Lesions were retrospectively scored with the Prostate Imaging Reporting and Data System (PI-RADS) (version 2) by radiologists who were blinded to the clinical-pathologic results. The IHC staining, including stains for the ETS-related gene, phosphatase and tensin homolog, androgen receptor, prostate specific antigen, and p53, was performed with targeted biopsy specimens of the index lesion (highest suspicion at MRI and pathologic grade) and scored by pathologists who were blinded to clinical-pathologic outcomes. Cox proportional hazards regression analysis was used to evaluate associations with recurrence-free survival (RFS). Results The median RFS was 31.7 months (range, 1-101 months) for 39 patients (median age, 62 years; age range, 47-76 years) without BCR and 14.6 months (range, 1-61 months) for 40 patients (median age, 59 years; age range, 47-73 years) with BCR. MRI features that showed a significant relationship with the RFS interval included an index lesion with a PI-RADS score of 5 (hazard ratio [HR], 2.10; 95% CI: 1.05, 4.21; P = .04); index lesion burden, defined as ratio of index lesion volume to prostate volume (HR, 1.55; 95% CI: 1.2, 2.1; P = .003); and suspicion of extraprostatic extension (EPE) (HR, 2.18; 95% CI: 1.1, 4.2; P = .02). Presurgical multivariable analysis indicated that suspicion of EPE at MRI (adjusted HR, 2.19; 95% CI: 1.1, 4.3; P = .02) and p53 stain intensity (adjusted HR, 2.22; 95% CI: 1.0, 4.7; P = .04) were significantly associated with RFS. Conclusion MRI features, including Prostate Imaging Reporting and Data System score, index lesion burden, extraprostatic extension, and preoperative guided biopsy p53 immunohistochemistry stain intensity are associated with biochemical relapse of prostate cancer after surgery. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Costa in this issue.

Analytic, Preanalytic, and Clinical Validation of p53 IHC for Detection of TP53 Missense Mutation in Prostate Cancer

Purpose:TP53 missense mutations may help to identify prostate cancer with lethal potential. Here, we preanalytically, analytically, and clinically validated a robust IHC assay to detect subclonal and focal TP53 missense mutations in prostate cancer.Experimental Design: The p53 IHC assay was performed in a CLIA-accredited laboratory on the Ventana Benchmark immunostaining system. p53 protein nuclear accumulation was defined as any p53 nuclear labeling in >10% of tumor cells. Fifty-four formalin-fixed paraffin embedded (FFPE) cell lines from the NCI-60 panel and 103 FFPE prostate cancer tissues (88 primary adenocarcinomas, 15 metastases) with known TP53 mutation status were studied. DU145 and VCaP xenografts were subjected to varying fixation conditions to investigate the effects of preanalytic variables. Clinical validation was performed in two partially overlapping radical prostatectomy cohorts.Results: p53 nuclear accumulation by IHC was 100% sensitive for detection of TP53 missense mutations in the NCI-60 panel (25/25 missense mutations correctly identified). Lack of p53 nuclear accumulation was 86% (25/29) specific for absence of TP53 missense mutation. In FFPE prostate tumors, the positive predictive value of p53 nuclear accumulation for underlying missense mutation was 84% (38/45), whereas the negative predictive value was 97% (56/58). In a cohort of men who experienced biochemical recurrence after RP, the multivariable HR for metastasis among cases with p53 nuclear accumulation compared with those without was 2.55 (95% confidence interval, 1.1-5.91).Conclusions: IHC is widely available method to assess for the presence of deleterious and heterogeneous TP53 missense mutations in clinical prostate cancer specimens. Clin Cancer Res; 23(16); 4693-703. ©2017 AACR.

Combining p53 stabilizers with metformin induces synergistic apoptosis through regulation of energy metabolism in castration-resistant prostate cancer

Since altered energy metabolism is a hallmark of cancer, many drugs targeting metabolic pathways are in active clinical trials. The tumor suppressor p53 is often inactivated in cancer, either through downregulation of protein or loss-of-function mutations. As such, stabilization of p53 is considered as one promising approach to treat those cancers carrying wild type (WT) p53. Herein, SIRT1 inhibitor Tenovin-1 and polo-like kinase 1 (Plk1) inhibitor BI2536 were used to stabilize p53. We found that both Tennovin-1 and BI2536 increased the anti-neoplastic activity of metformin, an inhibitor of oxidative phosphorylation, in a p53 dependent manner. Since p53 has also been shown to regulate metabolic pathways, we further analyzed glycolysis and oxidative phosphorylation upon drug treatments. We showed that both Tennovin-1 and BI2536 rescued metformin-induced glycolysis and that both Tennovin-1 and BI2536 potentiated metformin-associated inhibition of oxidative phosphorylation. Of significance, castration-resistant prostate cancer (CRPC) C4-2 cells show a much more robust response to the combination treatment than the parental androgen-dependent prostate cancer LNCaP cells, indicating that targeting energy metabolism with metformin plus p53 stabilizers might be a valid approach to treat CRPC carrying WT p53.

Enhanced tumor suppression in vitro and in vivo by co-expression of survivin-specific siRNA and wild-type p53 protein

The development of malignant prostate cancer involves multiple genetic alterations. For example, alterations in both survivin and p53 are reported to have crucial roles in prostate cancer progression. However, little is known regarding the interrelationships between p53 and survivin in prostate cancer. Our data demonstrate that the expression of survivin is inversely correlated with that of wtp53 protein (r(s)=0.548) in prostate cancer and in normal prostate tissues. We have developed a therapeutic strategy, in which two antitumor factors, small interfering RNA-survivin and p53 protein, are co-expressed from the same plasmid, and have examined their effects on the growth of PC3, an androgen-independent prostate cancer cell line. When p53 was expressed along with a survivin-specific short hairpin RNA (shRNA), tumor cell proliferation was significantly suppressed and apoptosis occurred. In addition, this combination also abrogated the expression of downstream target molecules such as cyclin-dependent kinase 4 and c-Myc, while enhancing the expression of GRIM19. These changes in gene expression occurred distinctly in the presence of survivin-shRNA/wtp53 compared with control or single treatment groups. Intratumoral injection of the co-expressed construct inhibited the growth and survival of tumor xenografts in a nude mouse model. These studies revealed evidence of an interaction between p53 and survivin proteins plus a complex signaling network operating downstream of the wtp53-survivin pathway that actively controls tumor cell proliferation, survival and apoptosis.

A novel, spontaneously immortalized, human prostate cancer cell line, Bob, offers a unique model for pre-clinical prostate cancer studies

INTRODUCTION

New in vitro models of castration-resistant prostate cancer (CRPC) are urgently required.

METHODS

Trans-rectal needle biopsies (TRBP) of the prostate were performed for research purposes on progressing CRPC patients who had not received prior treatment to the prostate. Biopsies were immediately digested with collagenase and plated onto collagen-coated flasks with a feeder layer of 3T6 cells and cultured in cytokine-supplemented keratinocyte serum-free medium.

RESULTS

Biopsies from 25 patients were collected and one of these, following an initial period of crisis, spontaneously immortalized. A series of cell lines called Bob were then established from a clone that survived CD133-selection followed by 4 weeks under adhesion-independent conditions in methylcellulose. Gains and losses previously described in clinical prostate tumors, most notably loss of 8(p) and gain of 8(q), were identified on comparative genomic hybridization and long-term growth in culture, survival in methylcellulose and invasion through matrigel confirmed the malignant phenotype of Bob. Furthermore, Bob expressed high levels of p53 and markers of early differentiation, including K8, prostatic acid phosphatase and prostate stem cell antigen. There was, however, no in vivo growth and ERG and ETV1 were not rearranged. Growth in serum permitted some differentiation.

CONCLUSION

This is the first spontaneously immortalized prostate cancer cell line to be established from a TRBP of a patient with CRPC. Bob is a novel pre-clinical model for functional studies in CRPC and especially for studying the CRPC "basal" phenotype.

Clinical significance of p53 alterations in surgically treated prostate cancers

Despite the high number of previous studies, the role of p53 alterations in prostate cancer is not clearly defined. To address the role of p53 alterations in prostate cancer biology, a total of 2514 cancers treated by radical prostatectomy were successfully analyzed by immunohistochemistry in a tissue microarray format. Overall a low rate of p53-positive tumors was found (2.5%). A significant underestimation of p53-positive cases was excluded by subsequent large section analyses and direct sequencing of the p53 gene in subsets of our patients. Large section analysis of 23 cases considered negative on the tissue microarray yielded only one weakly p53-positive tumor. Only 4 out of 64 (6.4%) high-grade tumors, that were considered negative for p53 by immunohistochemistry, presented exon 5-8 mutations. These data suggest a high sensitivity of our immunohistochemistry approach and confirm the overall low frequency of p53 alterations in clinically localized prostate cancer. A positive p53 immunostaining was strongly associated with presence of exon 5-8 mutations (P<0.0001), advanced pT-stage (P<0.0001), high Gleason grade (P<0.0001), positive surgical margins (P=0.03) and early biochemical tumor recurrence (P<0.0001). A higher rate of positive p53 immunostaining was detected in late-stage diseases including metastatic prostate cancer (P=0.0152) and hormone-refractory tumors (P=0.0003). Moreover, p53 expression was identified as an independent predictor of biochemical tumor recurrence in the subgroup of low- and intermediate-grade cancers. In summary, the results of this study show that p53 mutations characterize a small biologically aggressive subgroup of prostate cancers with a high risk of progression after prostatectomy. The rate of p53 alterations increases with prostate cancer progression.

Mapping of TMPRSS2-ERG fusions in the context of multi-focal prostate cancer

TMPRSS2-ERG gene fusion leading to the androgenic induction of the ERG proto-oncogene expression is a highly prevalent oncogenic alteration in prostate tumor cells. Prostate cancer is a multi-focal disease, and the origins as well as biological contribution of multiple cancer foci remain unclear with respect to prostate cancer onset or progression. To assess the role of TMPRSS2-ERG alteration in prostate cancer onset and/or progression, we have evaluated the status of fusion transcripts in benign glands, prostatic intraepithelial neoplasia (PIN) and multiple cancer foci of each prostate. Quantitative expression of TMPRSS2-ERG fusion type A and C transcripts was analyzed in benign, tumor and PIN areas, selected from whole-mount radical prostatectomy slides. TMPRSS2-ERG expression was correlated with clinicopathological features. Overall, 30 of 45 (67%) patients exhibited TMPRSS2-ERG fusion transcripts in at least one tumor focus. Of 80 tumor foci analyzed, 39 had TMPRSS2-ERG fusion (type A only: 30, type C only: 2, both types A and C: 7), with predominant detection of the TMPRSS2-ERG fusion type A (27/30, 90%) in the index tumors. Of 14 PIN lesions, 2 were positive for type A fusion. Frequent presence of the TMPRSS2-ERG in index tumors suggests critical roles of ERG alterations in the onset and progression of a large subset of prostate cancer. However, heterogeneity of the TMPRSS2-ERG detection in the context of multiple cancer foci and its frequency in PIN also support the role of other genomic alterations in the origins of prostate cancer.

Cancer statistics, 2007

Each year, the American Cancer Society (ACS) estimates the number of new cancer cases and deaths expected in the United States in the current year and compiles the most recent data on cancer incidence, mortality, and survival based on incidence data from the National Cancer Institute, Centers for Disease Control and Prevention, and the North American Association of Central Cancer Registries and mortality data from the National Center for Health Statistics. This report considers incidence data through 2003 and mortality data through 2004. Incidence and death rates are age-standardized to the 2000 US standard million population. A total of 1,444,920 new cancer cases and 559,650 deaths for cancers are projected to occur in the United States in 2007. Notable trends in cancer incidence and mortality rates include stabilization of the age-standardized, delay-adjusted incidence rates for all cancers combined in men from 1995 through 2003; a continuing increase in the incidence rate by 0.3% per year in women; and a 13.6% total decrease in age-standardized cancer death rates among men and women combined between 1991 and 2004. This report also examines cancer incidence, mortality, and survival by site, sex, race/ethnicity, geographic area, and calendar year, as well as the proportionate contribution of selected sites to the overall trends. While the absolute number of cancer deaths decreased for the second consecutive year in the United States (by more than 3,000 from 2003 to 2004) and much progress has been made in reducing mortality rates and improving survival, cancer still accounts for more deaths than heart disease in persons under age 85 years. Further progress can be accelerated by supporting new discoveries and by applying existing cancer control knowledge across all segments of the population.

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.

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.

Response of tertiary centres to pressure changes. Is there a mechano-electrical association?

Inactivation of the tumor suppressor gene p53 is commonly observed in human prostate cancer and is associated with therapeutic resistance. We have previously demonstrated that green tea polyphenols (GTP) induce apoptosis in prostate cancer cells irrespective of p53 status. However, the molecular mechanisms underlying these observations remain elusive. Here we investigated the mechanisms of GTP-induced apoptosis in human prostate cancer LNCaP cells stably-transfected with short hairpin-RNA against p53 (LNCaPshp53) and control vector (LNCaPshV). GTP treatment induced p53 stabilization and activation of downstream targets p21/waf1 and Bax in a dose-dependent manner specifically in LNCaPshV cells. However, GTP-induced FAS upregulation through activation of c-jun-N-terminal kinase resulted in FADD phosphorylation, caspase-8 activation and truncation of BID, leading to apoptosis in both LNCaPshV and LNCaPshp53 cells. In parallel, treatment of cells with GTP resulted in inhibition of survival pathway, mediated by Akt deactivation and loss of BAD phosphorylation more prominently in LNCaPshp53 cells. These distinct routes of cell death converged to a common pathway, leading to loss of mitochondrial transmembrane potential, cytochrome c release and activation of terminal caspases, resulting in PARP-cleavage. GTP-induced apoptosis was attenuated with JNK inhibitor, SP600125 in both cell lines; whereas PI3K-Akt inhibitor, LY294002 resulted in increased cell death prominently in LNCaPshp53 cells, establishing the role of two distinct pathways of GTP-mediated apoptosis. Furthermore, GTP exposure resulted in inhibition of class I HDAC protein, accumulation of acetylated histone-H3 in total cellular chromatin, resulting in increased accessibility of transcription factors to bind with the promoter sequences of p21/waf1 and Bax, regardless of the p53 status of cells, consistent with effects elicited by an HDAC inhibitor, trichostatin A. These results demonstrate that GTP induces prostate cancer cell death by two distinct mechanisms regardless of p53 status, thus identifying specific well-defined molecular mechanisms that may be targeted by chemopreventive and/or therapeutic strategies.