Prognostic markers in prostate cancer

Prostate-Specific Membrane Antigen (PSMA) Expression Predicts Need for Early Treatment in Prostate Cancer Patients Managed with Active Surveillance

Metabolic dysregulation is an early event in carcinogenesis. Here, we examined the expression of enzymes involved in de novo lipogenesis (ATP-citrate lyase: ACLY), glucose uptake (Glucose Transporter 1: GLUT1), and folate-glutamate metabolism (Prostate-Specific Membrane Antigen: PSMA) as potential biomarkers of risk for early prostate cancer progression. Patients who were managed initially on active surveillance with a Gleason score of 6 or a low-volume Gleason score of 7 (3 + 4) were accrued from a prostate cancer diagnostic assessment program. Patients were asked to donate their baseline diagnostic biopsy tissues and permit access to their clinical data. PSMA, GLUT1, and ACLY expression were examined with immunohistochemistry (IHC) in baseline biopsies, quantitated by Histologic Score for expression in benign and malignant glands, and compared with patient time remaining on active surveillance (time-on-AS). All three markers showed trends for elevated expression in malignant compared to benign glands, which was statistically significant for ACLY. On univariate analysis, increased PSMA and GLUT1 expression in malignant glands was associated with shorter time-on-AS (HR: 5.06, [CI 95%: 1.83-13.94] and HR: 2.44, [CI 95%: 1.10-5.44], respectively). Malignant ACLY and benign gland PSMA and GLUT1 expression showed non-significant trends for such association. On multivariate analysis, overexpression of PSMA in malignant glands was an independent predictor of early PC progression (p = 0.006). This work suggests that the expression of metabolic enzymes determined by IHC on baseline diagnostic prostate biopsies may have value as biomarkers of risk for rapid PC progression. PSMA may be an independent predictor of risk for progression and should be investigated further in systematic studies.

Use of Glycoproteins-Prostate-Specific Membrane Antigen and Galectin-3 as Primary Tumor Markers and Therapeutic Targets in the Management of Metastatic Prostate Cancer

Simple Summary

Prostate specific membrane antigen and galectins are proteins expressed on cell surface and their expression is associated with cancer growth and spread. The goal of this research was to look at the pattern of these two glycoproteins in the human prostate cancer microenvironment. Prostate specific membrane antigen and galectins-1,3 and 8 were the most frequently detected glycoproteins in various phases of this disease. Furthermore, prostate specific membrane antigen and galectin-3 expression are good indicators of tumor aggressiveness, and their combined expression can be valuable tool for prostate cancer diagnosis and treatment in future. Together, our findings reveal a tightly regulated “Prostate specific membrane antigen-galectin-pattern” that accompanies disease in prostate cancer and point to a key role for combined prostate specific membrane antigen and galectin-3 inhibitors in prostate cancer treatment along with standard chemotherapy.

Abstract

Galectins and prostate specific membrane antigen (PSMA) are glycoproteins that are functionally implicated in prostate cancer (CaP). We undertook this study to analyze the “PSMA-galectin pattern” of the human CaP microenvironment with the overarching goal of selecting novel-molecular targets for prognostic and therapeutic purposes. We examined CaP cells and biopsy samples representing different stages of the disease and found that PSMA, Gal-1, Gal-3, and Gal-8 are the most abundantly expressed glycoproteins. In contrast, other galectins such as Gal-2, 4–7, 9–13, were uniformly expressed at lower levels across all cell lines. However, biopsy samples showed markedly higher expression of PSMA, Gal-1 and Gal-3. Independently PSA and Gleason score at diagnosis correlated with the expression of PSMA, Gal-3. Additionally, the combined index of PSMA and Gal-3 expression positively correlated with Gleason score and was a better predictor of tumor aggressiveness. Together, our results recognize a tightly regulated “PSMA-galectin- pattern” that accompanies disease in CaP and highlight a major role for the combined PSMA and Gal-3 inhibitors along with standard chemotherapy for prostate cancer treatment. Inhibitor combination studies show enzalutamide (ENZ), 2-phosphonomethyl pentanedioic acid (2-PMPA), and GB1107 as highly cytotoxic for LNCaP and LNCaP-KD cells, while Docetaxel (DOC) + GB1107 show greater efficacy in PC-3 cells. Overall, 2-PMPA and GB1107 demonstrate synergistic cytotoxic effects with ENZ and DOC in various CaP cell lines.

p53, Bcl-2 and AgNOR tissue markers: model approach in predicting prostate cancer characteristics

The balance between proliferation and apoptosis is represented by changes in the expression of the tissue markers, Bcl-2 and p53, and the presence of silver-stained nucleolar organizing regions (AgNOR) on DNA in prostate adenocarcinomas. Identifying a mathematical model that would take into account the opposing nature of both processes and relate this to cancer stage and grade would be a useful adjunct for studying disease behaviour. This retrospective study investigated tissue marker expression in prostate adenocarcinoma biopsy samples from 17 patients. Staining for p53 was inversely correlated with patient age. Staining for Bcl-2 correlated with the presence of advanced metastatic cancer and American Joint Committee on Cancer (AJCC) disease stage. A mathematical model was developed which combined coded staining intensity data for Bcl-2 and AgNOR, as markers of proliferation, and for p53, as a marker of apoptotis. The mathematical model significantly correlated with Gleason score, AJCC stage and serum prostate specific antigen level, whereas each tissue marker alone did not correlate with all these measures.

Prostate-specific membrane antigen expression as a predictor of prostate cancer progression

Distinguishing aggressive prostate cancer from indolent disease represents an important clinical challenge, because current therapy may lead to overtreatment of men with limited disease. The prostate-specific membrane antigen (PSMA) is a membrane-bound glycoprotein that is highly restricted to the prostate. Previously, studies analyzing the expression of PSMA have found an up-regulation in correlation with prostate cancer, particularly in advanced cancer. This association is ideal for an application as a prognostic marker. In the current study, we characterized PSMA expression in a high-risk cohort and evaluated its potential use as predictive marker of prostate-specific antigen (PSA) recurrence. PSMA expression was analyzed by immunohistochemistry using tissue microarrays composed of tumor samples from 450 patients. Protein intensity was recorded using a semiautomated quantitative microscope system (ACIS II; Clarient Chromavision Medical Systems, San Juan Capistrano, CA). PSMA expression levels differed significantly (P < .001) between benign prostatic tissue, localized prostate cancer, and lymph node metastases. Dividing the cohort into high- and low-PSMA expressing cancers based on the median area of positive staining, we found that high PSMA levels were associated with significant increase of PSA recurrence (P = .004). This was independent of clinical parameters such as lymph node tumor burden (lymph node density, >20%; P < .001), extraprostatic extension (P = .017), seminal vesicle invasion (P < .001), and high Gleason score (8-10, P = .006). In a multivariate model, PSMA expression and metastases to pelvic lymph nodes were significantly associated with time to PSA recurrence (HR, 1.4; 95% confidence interval, 1.1-2.8, P = .017; and hazard ratio, 5; 95% confidence interval, 2.6-9.7, P < .001, respectively). In summary, PSMA is independently associated with PSA recurrence in a high-risk cohort and thus might provide insight into the additional use of adjuvant therapy. Validation on other cohorts is required.

Expression of nuclear factor-kappa B and I kappa B alpha proteins in prostatic adenocarcinomas: correlation of nuclear factor-kappa B immunoreactivity with disease recurrence

PURPOSE

The nuclear transcription factor nuclear factor-kappa B (NF kappa B) and its inhibitor, I kappa B, regulate the transcription of various genes involved in cell proliferation, adhesion, and survival. The NF kappa B transcription factor complex plays a role in cancer development and progression through its influence on apoptosis. More recently, NF kappa B has been shown to be activated in human and androgen-independent prostate cancer cells. To our knowledge, this is the first study demonstrating the prognostic significance of NF kappa B immunoreactivity in prostate adenocarcinomas (PACs).

EXPERIMENTAL DESIGN

Using prostatectomy specimens, we performed immunohistochemical staining for NF kappa B and I kappa B alpha (Santa Cruz Biotechnology) on formalin-fixed, paraffin-embedded sections obtained from 136 patients with PAC. Cytoplasmic and nuclear immunoreactivity was scored for intensity and distribution, and results were correlated with preoperative serum prostate-specific antigen, tumor grade, stage, DNA ploidy (Feulgen spectroscopy), and biochemical disease recurrence.

RESULTS

Forty-nine percent of PACs overexpressed cytoplasmic NF kappa B, and 63% showed decreased I kappa B expression. Cytoplasmic NF kappa B overexpression correlated with advanced tumor stage (P = 0.048), aneuploidy (P = 0.022), and biochemical disease recurrence (P = 0.001). When we compared the means for the NF kappa B-positive and -negative subgroups, NF kappa B overexpression correlated with preoperative serum prostate-specific antigen (P = 0.04) and DNA index (P = 0.05). Fifteen percent of PACs expressed nuclear NF kappa B, which correlated with high tumor grade (P = 0.001) and advanced stage (P = 0.05). Decreased I kappa B alpha expression correlated with high tumor grade (P = 0.015). On multivariate analysis, tumor stage (P = 0.043) and NF kappa B overexpression (P = 0.006) were independent predictors of biochemical recurrence.

CONCLUSION

These results support a role for NF kappa B pathway proteins in the tumorigenesis of PACs. The findings are also consistent with reported experimental studies suggesting a new strategy of combined chemotherapy and specific NF kappa B blockade in decreasing the rate of disease relapse.

The assessment of PTEN tumor suppressor gene in combination with Gleason scoring and serum PSA to evaluate progression of prostate carcinoma

OBJECTIVE

The purpose of the study was to determine if the tumor suppressor gene phosphate and tensin homolog (PTEN) (mutated in multiple advanced cancers 1) in combination with Gleason scoring and serum prostate specific antigen (PSA) could be employed to better predict the progression of prostate carcinoma.

MATERIALS AND METHODS

The study group consisted of 43 patients with benign prostate hyperplasia (BPH), 15 with organ confined prostate carcinoma (OCPCa), and 18 with advanced prostate carcinoma (APCa). Prostate tissue samples were obtained from radical prostatectomy, transurethral resection, and TRUS guided trans-rectal needle biopsy and then evaluated for biomarker expression. The clinical stage was assessed according to tumor node metastasis classification and grade according to Gleason system. Serum PSA was measured by conventional techniques and Western blotting analysis was used to determine PTEN expression in the primary tissue. Multivariate analysis was performed to analyze whether these markers could individually predict the progression of prostate carcinoma.

RESULTS

APCa patients displayed higher Gleason scores and serum PSA levels. But much lower PTEN expression was detected in prostate of APCa patients compared to patients with BPH or OCPCa. Hormone refractory (HR) and hormone sensitive (HS) APCa cases did not yield any significant differences in terms of Gleason scoring, serum PSA and PTEN expression. PSA levels were significantly higher in patients with OCPCa or APCa compared to patients with BPH.

CONCLUSION

Our results suggested that both PTEN and serum PSA appeared to be useful as independent markers to depict the nature of tumor behavior as benign or malign. In addition, PTEN also appeared to be useful as an independent marker to predict the progression of prostate carcinoma.

Expression of cysteine protease protein 32 in prostatic adenocarcinoma correlates with tumor grade

CONTEXT

Controlled cell death is mediated by apoptosis-specific genes, tumor suppressor genes, and oncogenes. The caspase family is a group of at least 15 known cysteine proteases that serve as initiator and effector molecules of the apoptosis pathway. On activation, caspases cause cell shrinkage, condensation of chromatin, fragmentation of DNA, and the formation of blebs in the cytoplasmic membrane.

OBJECTIVES

The patterns of cysteine protease protein (CCP) 32 (caspase-3) expression have been determined in normal human tissues and a variety of tumors, and have been shown to correlate with the outcome in breast cancer and linked to resistance to chemotherapy in other tumors. This study was performed to determine whether CPP32 is expressed in prostatic adenocarcinoma and to define its relationship with outcome variables.

DESIGN

Formalin-fixed, paraffin-embedded radical prostatectomy specimens from 211 patients with prostatic adenocarcinoma were evaluated for CPP32 expression by immunohistochemistry. Hematoxylin-eosin-stained slides were reviewed, and tumors were graded based on the Gleason grading system. Tumors were scored for CPP32 expression semiquantitatively, based on the staining intensity and distribution patterns. These results were compared with Gleason grade and clinical and pathologic stages.

RESULTS

One hundred thirty-three (63%) of 211 cases showed high expression of CPP32, whereas expression was low in 78 (37%) cases. One hundred three (49%) of 211 cases had a high Gleason score (7 and above). Of 103 cases with a high Gleason score, 74 (72%) showed high CPP32 expression. Strong cytoplasmic staining for CPP32 in high-grade tumors was statistically significant (P =.01). Also, by linear regression analysis a significant correlation was seen between the Gleason score and the cytoplasmic CPP32 expression (P =.001). Expression of CPP32 did not correlate with either clinical stage (P =.28) or pathologic stage (P =.60); however, this study included very few patients with stage IV disease.

CONCLUSION

The correlation between CPP32 and high tumor grade suggests a CPP32-related high turnover rate in high-grade prostatic adenocarcinoma. Moreover, strong correlation with Gleason grade, a powerful predictor of disease progression and overall survival, suggests potential usefulness of CPP32 as a prognostic factor, especially in limited biopsy samples.

Molecular and genetic prognostic factors of prostate cancer

Prostate cancer is the most commonly diagnosed cancer in Western males, responsible for 3% of all deaths in men over 55 years of age and second only to lung cancer as a cause of cancer death. Biomarkers have become an important diagnostic tool in prostate cancer. The discovery of the serum marker prostate-specific antigen (PSA) significantly facilitated the detection and management of prostate cancer. As we enter into the post-genomics era, novel biomarkers of prostate cancer of therapeutic significance will invariably emerge. Here we review a series of existing and emerging molecular-based prognostic markers particularly with radiotherapy.

Prostate cancer biomarkers: a current perspective

Genomic- and proteomic-based studies have led to the identification of a large number of candidate biomarkers, as well as signature patterns of multiple markers for prostate cancer diagnosis, disease progression and prediction of survival. While these candidates include the usual suspects, including oncogenes, proliferation markers and cytoskeletal proteins, there are many additional unexpected molecules such as those involved in processes such as transcriptional repression and fatty acid metabolism. Patterns of expression serving as useful biomarkers is a new and, as yet, clinically untested concept which promises to permit a consideration of the complex milieu of cancer. Exciting as these developments are, clinical application will have to await careful validation of these candidates by independent biochemical approaches over large and diverse samples.

Experimental therapy of human prostate cancer by inhibiting MDM2 expression with novel mixed-backbone antisense oligonucleotides: in vitro and in vivo activities and mechanisms

BACKGROUND

MDM2 oncogene is overexpressed in many human cancers including prostate cancer and MDM2 levels are associated with poor prognosis. This study was undertaken to investigate the functions of MDM2 oncogene in prostate cancer growth and the value of MDM2 as a drug target for prostate cancer therapy by inhibiting MDM2 expression.

METHODS

Antisense anti-human-MDM2 mixed-backbone oligonucleotide and its mismatch control were tested in in vitro and in vivo human prostate cancer models (LNCaP, DU 145, and PC-3) for anti-tumor activity. Targeted gene products and related proteins were analyzed and the anti-tumor activity was determined when the oligonucleotides were used alone or in combination with cancer therapeutics.

RESULTS

The antisense oligonucleotide specifically inhibited MDM2 expression in a dose- and time-dependent manner, resulting in significant anti-tumor activity in vitro and in vivo. In LNCaP cells, p53 and p21 levels were elevated. The antisense oligonucleotide also potentiated the effects of p53 activation and p21 induction by chemotherapeutic agents 10-hydroxycamptothecin, adriamycin, 5-fluorouracil, and paclitaxel. In DU145 cells, following inhibition of MDM2 expression, p21 levels were elevated although p53 levels remained unchanged. In both cell lines, the antisense oligonucleotide inhibited tumor cell growth and induced apoptosis in vitro. In a dose-dependent manner, the antisense oligonucleotide showed anti-tumor activity in nude mice bearing DU145 or PC-3 xenografts. It significantly increased therapeutic effectiveness of the chemotherapeutic agent irinotecan and slightly improved the effects of paclitaxel and Rituxan.

CONCLUSIONS

These results indicate that MDM2 has a role in prostate tumor growth through both p53-dependent and p53-independent mechanisms, indicating that MDM2 inhibitors have a broad spectrum of anti-tumor activities in human prostate cancers regardless of p53 status.

Quantitative imaging of the T cell antitumor response by positron-emission tomography

We describe a noninvasive, quantitative, and tomographic method to visualize lymphocytes within the whole animal. We used positron-emission tomography (PET) to follow the localization of adoptively transferred immune T lymphocytes. Splenic T cells from animals that had rejected a Moloney murine sarcoma virus/Moloney murine leukemia virus (M-MSV/M-MuLV)-induced tumor were marked with a PET reporter gene, injected into tumor-bearing mice, and imaged in a microPET by using a substrate specific for the reporter. Specific localization of immune T cells to the antigen-positive tumor was detected over time, by sequential imaging of the same animals. Naive T cells did not localize to the tumor site, indicating that preimmunization was required. Autoradiography and immunohistochemistry analysis corroborated the microPET data. The method we have developed can be used to assess the effects of immunomodulatory agents intended to potentiate the immune response to cancer, and can also be useful for the study of other cell-mediated immune responses, including autoimmunity.