Fluorescence in situ hybridization study of HER-2/neu oncogene amplification in prostate cancer

The prevalence and clinical significance of HER2 expression in prostate adenocarcinoma

AIMS

Abnormalities in HER2 are well-established oncogenic drivers and are approved therapeutic targets in various malignancies. Prior studies evaluating HER2 expression in prostate cancer (PCa) have yielded variable results. Most of these studies used immunohistochemistry scoring systems based on breast cancer data. The goal of this study was to determine the prevalence and clinical significance of HER2 expression using a scoring system that better reflects the HER2 staining pattern observed in PCa.

METHODS

We randomly selected similar numbers of localized low risk (AJCC stage I), locally advanced (AJCC stages II & III), and metastatic (AJCC stage IV) PCa patients treated at the DC VA Medical Center between 2000 and 2022. Among them, we included patients who had sufficient PCa tissue samples and clinical information required for this analysis. Two experienced pathologists independently scored HER2 expression (Ventana Pathway anti-HER2) according to a modified gastric cancer HER2 scoring system.

RESULTS

Out of the 231 patients included, 85 % self-identified as Black. 58.9 % of patients expressed HER2 (1+: 35.5 %; 2+: 18.2 %; 3+: 5.2 %). Validity of the results was confirmed using the HercepTest antibody. Higher HER2 expression was associated with a higher Gleason Score/Grade Group and advanced disease.

CONCLUSIONS

Our findings support the adverse prognostic impact on HER2 in PCa. We propose the use of a modified scoring system to evaluate HER2 expression in PCa. The observed high prevalence of HER2 expression supports the consideration of novel HER2-targeted therapies addressing even low levels of HER2 expression in future PCa trials.

Her-2/Neu Receptor in Prostate Cancer Development and Progression to Androgen Independence

Development of prostate cancer and progression to androgen-independent disease is correlated with increased expression of growth factors and receptors capable of establishing autocrine and/or paracrine growth-stimulatory loops. A thorough review was made of the current literature and recent abstract presentations at scientific meetings focusing on the role of the HER-2/neu (c-erbB2) receptor in prostate cancer and the potential clinical usefulness of its specific inhibitors. In the past 10 years, conflicting results on HER-2/neu expression in prostate cancer have been reported. More recently, four studies have shown experimental evidence of HER-2/neu in the development of prostate cancer and, more specifically, in the progression to a hormone-refractory clinical behavior. Furthermore, it has been proposed that HER-2 family and androgen receptors function synergistically in the absence of androgen, which suggests a crosstalk between the HER-2/neu and androgen receptor pathways. Finally, clinical trials are in progress in prostate cancer patients to test novel agents that selectively interfere with HER-2/neu activity.

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.

HER2 gene amplification in patients with prostate cancer: Evaluating a CISH-based method

Prostate cancer (PCa) is one of the most widespread malignancies in the world. The role of the human epidermal growth factor receptor 2 (HER2) in the pathogenesis and progression of human PCa remains poorly understood. In contradiction with breast cancer, studies on HER2 overexpression and gene amplification in PCa have produced varying results, although the HER2 oncogene has been implicated in the biology of numerous tumor types, and serves as a prognostic marker and therapeutic target in breast cancer. Technical challenges are considered the main reasons for data discrepancies. Amplification of the HER2 gene has previously been reported in PCa, in which it was associated with tumor progression. The present study aimed to evaluate the prevalence and clinical significance of HER2 amplification in PCa. A total of 32 biopsy samples obtained from human prostate adenocarcinomas were evaluated by chromogenic in situ hybridization (CISH) to determine the frequency of patients with HER2 gene amplifications. High copy numbers of HER2 were detected in 19 of the prostate tumors analyzed. The results of the present study suggested that, in patients without amplification of HER2, high levels of prostate-specific antigen or a high Gleason score were not significantly correlated with a high pathologic stage. Furthermore, amplification levels of the HER2 gene were directly associated with pathologic stage in patients with PCa. Therefore, the potential use of HER2 as a prognostic factor or therapeutic target for PCa warrants further study.

Matriptase is involved in ErbB-2-induced prostate cancer cell invasion

Deregulation of both ErbB-2 signaling and matriptase activity has been associated with human prostate cancer (PCa) progression. In this communication, we investigated the roles of both ErbB-2 signaling in matriptase zymogen activation and matriptase in ErbB-2-induced PCa malignancy. In a human PCa cell progression model, we observed that advanced PCa C-81 LNCaP cells exhibited an aggressive phenotype with increased cell migration and invasion capacity; these cells concurrently showed both enhanced ErbB-2 phosphorylation and increased matriptase zymogen activation compared with parental C-33 LNCaP cells. Moreover, ErbB2 activation, both ligand-dependent (eg, epidermal growth factor treatment) and ligand-independent (eg, overexpression), was able to induce matriptase zymogen activation in this cell line. Inhibition of ErbB-2 activity by either the specific inhibitor, AG825, in epidermal growth factor-treated C-33 LNCaP cells or ErbB-2 knockdown in C-81 LNCaP cells, reduced matriptase activation. These observations were confirmed by similar studies using both DU145 and PC3 cells. Together, these data suggest that ErbB-2 signaling plays an important role in matriptase zymogen activation. ErbB-2-enhanced matriptase activation was suppressed by a phosphatidylinositol 3-kinase inhibitor (ie, LY294002) but not by a MEK inhibitor (ie, PD98059). Suppression of matriptase expression by small hairpin RNA knockdown in ErbB-2-overexpressing LNCaP cells dramatically suppressed cancer cell invasion. In summary, our data indicate that ErbB-2 signaling via the phosphatidylinositol 3-kinase pathway results in up-regulated matriptase zymogen activity, which contributes to PCa cell invasion.

HER2 expression and gene amplification in pT2a Gleason score 6 prostate cancer incidentally detected in cystoprostatectomies: comparison with clinically detected androgen-dependent and androgen-independent cancer

Previous studies have demonstrated HER2 protein overexpression and/or gene amplification in a subset of patients with clinically significant prostate cancer (PCa), especially in the androgen-independent phase of the disease. There are no studies on incidentally detected PCa. The aim of the study was to analyze HER2 expression and gene amplification in PCa incidentally detected in cystoprostatectomies. High-grade prostatic intraepithelial neoplasia (HGPIN) was also investigated. Comparison was made with clinically detected PCa, both untreated and hormonally treated, and with androgen-independent PCa. Nineteen cystoprostatectomy (CyP) and 44 radical prostatectomy specimens (25 untreated and 19 hormonally treated) with pT2a Gleason score 6 cancer and HGPIN were used in this study. It also included 9 specimens of transurethral resection of the prostate with hormone-independent cancer and 8 cases of normal prostate tissue from CyP specimens without PCa and prostatic intraepithelial neoplasia. HER2 protein and Ki-67 were investigated immunohistochemically. Patients with immunohistochemical scores of 2+ and 3+ were considered to have HER2 overexpression (HercepTest method). Dual-color fluorescence in situ hybridization analysis was performed using the CEP-17/HER dual probe combination. High-grade prostatic intraepithelial neoplasia showed HER2 overexpression in 26% of the CyP cases and in 40% and 83% of the untreated and treated cases, respectively. Prostate cancer showed HER2 overexpression in 16% of cases in the CyP group and in 36% and 47.5% in the untreated and treated groups, respectively. HER2 overexpression was present in 78% of androgen-independent cancers. HER2 gene amplification was seen in a small proportion of nuclei and some of the cases. In HGPIN, it ranged from 1.1% (in 5 cases) in the CyP group to 2.1% (in 10 cases) and 1.9% (in 6 cases) in the untreated and treated groups, respectively. In PCa, the proportion of nuclei with gene amplification was 0.7% (in 3 cases) in the CyP group, 2.6% (in 10 cases) and 2.5% (in 12 cases) in the untreated and treated groups, respectively, and 9% (in 6 cases) in the androgen-independent PCa. Ki-67 expression in HGPIN and PCa in CyP specimens was lower than in the radical prostatectomies and cases of transurethral resection of the prostate. Our findings in the current HER2-related study indicate that incidentally detected cancer has features of less aggressiveness than clinically detected cancer. This may contribute to a better understanding of the results obtained in screening programs where insignificant cancers are detected along with clinically significant cancers.

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 Markers and Prostate Cancer Prognosis

Prostate cancer is the most common malignancy among American men and is the second-leading cause of cancer-related mortality. Although radical prostatectomy and radiation therapy offer hope for cure for the majority of men with localized tumors, we continue to lack the tools to definitively determine which cancers need to be treated, which cancers will recur after treatment, and which cancers will behave aggressively when they have metastasized. Recent breakthroughs in molecular biology have led to the identification of a number of potential biomarkers for prostate cancer, many of which have been suggested to have prognostic significance. Eventually, combinations of these markers will hopefully enable us to more rationally facilitate counseling and direct management for men with prostate cancer.

Newer Therapies in Advanced Prostate Cancer

Prostate cancer is a leading cause of morbidity and mortality among males. Androgen ablation as initial therapy for advanced prostate cancer provides high response rates but does not cure disease, as nearly all men with metastases will eventually progress to hormone-refractory prostate cancer (HRPC). Present chemotherapy regimens for HRPC can provide palliation and have recently demonstrated an increase in overall survival. Over the past 2 decades, these regimens represent clear advances in the treatment of metastatic prostate cancer but also demonstrate that newer therapies are needed. Studies are ongoing to provide viable alternatives among traditional cytotoxic therapies as well as among novel agents targeting specific molecular pathways. This article reviews some of the newer therapies being developed and evaluated, including the epothilone analogues, human epidermal growth factor receptor pathway inhibitors, angiogenesis inhibitors, and endothelin receptor antagonists.

Trastuzumab plus docetaxel in HER-2/neu-positive prostate carcinoma: final results from the California Cancer Consortium Screening and Phase II Trial

BACKGROUND

Overexpression of the HER-2/neu oncoprotein has been reported to occur in </= 60% of patients with prostate carcinoma and to correlate with shortened survival. Trastuzumab is a humanized monoclonal antibody to the HER-2 receptor and has activity against HER-2-positive breast carcinoma, more so when combined with a taxane. The authors screened for HER-2 overexpression in patients developing hormone-refractory prostate carcinoma (HRPC) and conducted a Phase II trial of trastuzumab plus docetaxel in HER-2-positive patients.

METHODS

Paraffin-embedded tumor specimens from potentially eligible patients were screened for HER-2 expression by immunohistochemistry (IHC) and/or amplification by fluorescent in situ hybridization (FISH). Shed HER-2 was also assessed by enzyme-linked immunoradsorbent assay (ELISA). Patients with HER-2-positive tumor specimens (IHC 2+ or 3+ or FISH ratio > 2) were initially randomized to receive either single-agent trastuzumab or docetaxel. After two treatment cycles, nonresponding patients received the trastuzumab/docetaxel combination. Treatment was comprised of 30 mg/m(2) of docetaxel weekly for 6 weeks followed by a 2-week break and 4 mg/kg of trastuzumab intravenously during Week 1 then 2 mg/kg per week thereafter. The cycle length was 8 weeks.

RESULTS

One hundred patients with HPRC were screened. IHC results were as follows: 3+ (n = 1), 2+ (n = 6), 1+ (n = 26), 0 (n = 39), and insufficient tissue specimen/not tested (n = 28). Only 3 of 37 patients had elevated shed HER-2 by ELISA (> 15 mg/mL). None overexpressed HER-2 by IHC. FISH amplification was found in 0 of 34 tissue samples. Of seven patients with IHC 3+ or 2+, four were tested by ELISA and two by FISH. None were abnormal. Age and Gleason score did not correlate with IHC status. Of the seven patients eligible for the Phase II study, only four agreed to participate. The trial was thus closed for nonfeasibility (the overall HER-2 positivity rate was < 20%). No patient responded to trastuzumab alone. The median survival was not reached and the median progression-free survival was 7 months.

CONCLUSIONS

HER-2 overexpression by IHC in archival prostate carcinoma specimens was infrequent. There was no apparent correlation among IHC, ELISA, and FISH, although the sample size was limited. Conclusions regarding the predictive value of HER-2 status on outcome after trastuzumab-based therapy were not reached and were only drawn after larger-scale screening efforts. The authors estimated that 1000 patients need to be screened to complete accrual to a 40-patient efficacy trial.

Expression of the epidermal growth factor receptor family in prostate carcinoma before and during androgen-independence

Novel palliative strategies for patients with androgen-independent prostate cancer (AIPC) include targeting the epidermal growth factor receptor (EGFR) family. The aim of the present study was to investigate intrapatient changes of EGFRs during the development of AIPC. In total, 106 symptomatic AIPC patients were identified in whom prostatic biopsies (adenocarcinoma) were available both before the start of androgen deprivation (PRTR biopsy) and after the development of AIPC (AIPC biopsy). All four known subgroups of the EGFR family were determined by immunohistochemistry (IHC): c-erbB-1 (EGFR), c-erbB-2 (HER2/neu), c-erbB-3 (HER3) and c-erbB-4 (HER4). Moderate to strong membrane-specific staining was recorded semiquantitatively (<10% vs ⩾10%=IHC stained tumour cells: ‘negative’ vs ‘positive’ staining). The medical records were reviewed for clinical variables. During the development of AIPC, intrapatient changes occurred in two opposite directions for each of the four EGFRs: negativity changed to positivity, and vice versa, statistically significant only for the increase of c-erbB-1 expression (P=0.001). The c-erbB-2 expression in the AIPC biopsy was associated with a significantly shorter survival from the time of the AIPC biopsy (P=0.029). Our results support ongoing therapeutic attempts of EGFR inhibition in subgroups of patients with prostate cancer. Further research is needed to understand the function of EGFRs in this malignancy.

HER2 and COX2 expression in human prostate cancer

COX2 and HER2 expression are associated with a poor prognosis in prostate cancer and HER2 has been linked to COX2 expression in colorectal cancer. The association between COX2 and HER2 expression was investigated in 117 patients with prostate cancer (89) or Benign prostatic hyperplasia (BPH) (28). Tissue was analysed for HER2 amplification by fluorescent in situ hybridisation, and HER2 and COX2 protein expression by immunohistochemistry (IHC). All tumours analysed expressed COX2 at a significantly higher level than BPH tissue (P=0.041). Only low levels of HER2 gene amplification (8%, 7/89) and HER2 protein expression (12%, 11/89) were observed. HER2 protein expression was rarely observed and did not correlate with HER2 amplification or COX2 expression. Although HER2 does not drive COX2 expression in prostate cancer, this study identified high levels of COX2 expressed in locally advanced prostate cancer, suggesting COX2 could be a potential therapeutic target. COX2 inhibitors are currently being used in clinical trials for the treatment of other tumour types.

Treatments for improving survival of patients with prostate cancer

Prostate cancer is a heterogeneous disease characterised by a long natural history relative to other solid tumours. With the diagnosis of prostate cancer being made earlier, the emphasis of treatment has shifted from palliation of symptoms to altering disease-related morbidity and mortality and thus improving overall survival. Treatment of prostate cancer increasingly involves an approach that combines local therapies directed at the primary tumour together with systemic therapies to potentiate their effect and to control subclinical metastatic disease. Patients with localised tumours who are at high risk of relapsing with radiation therapy alone are surviving longer because of the addition of adjuvant hormonal therapy. Although a survival benefit in similar patients undergoing prostatectomy has not yet been established, preliminary results indicate that adjuvant hormonal therapy delays relapse. Chemotherapy is an effective palliative modality for patients with hormone- refractory metastatic disease, and recently completed phase III trials will determine if chemotherapy can prolong survival for this group. The role of chemotherapy in patients with locally advanced tumours is also being investigated in randomised clinical trials. Because bone is the dominant site of metastases for most patients with prostate cancer, the development of therapies that can slow tumour growth specifically within bone is a logical strategy. Bisphosphonates and bone-targeted radionuclides are two such approaches that have shown encouraging results even in the most advanced stages of the disease. Although one can now reasonably hypothesise that survival has improved because of recent therapeutic advances, it remains to be conclusively established that cytotoxic or other systemic therapy can extend survival of patients with prostate cancer. Only the results of ongoing randomised trials can definitely establish that more patients with locally advanced and metastatic prostate cancer are living longer.

Involvement of Growth Factor Receptors of the Epidermal Growth Factor Receptor Family in Prostate Cancer Development and Progression to Androgen Independence

The development of prostate cancer and the progression from a normal prostate epithelium to androgen-dependent cancer and eventually to hormone-refractory prostate cancer is a multistep process involving several changes in the function of different growth-regulatory signals. In the past 10 years, conflicting results on epidermal growth factor receptor (EGFR) family expression in prostate cancer have been reported. These differences may result from technical differences, lack of standardization of immunohistochemical assays, or different scoring methodologies. Recently, 4 studies have shown experimental evidence of a role of the EGFR family, particularly ErbB-2, in the development of prostate cancer and, more specifically, in the progression to hormone-refractory clinical behavior. These 4 studies were similar in some relevant aspects, such as the patient population. In fact, the patients in each study were divided into 3 groups that represent the progression of prostate cancer. In 3 of 4 studies, a statistically significant increase in ErbB-2 expression was detected by immunohistochemistry in the progression from hormone-dependent to hormone-independent disease. The expression of EGFR was also evaluated in 1 of the 4 studies. In a recent report from our group, a significant increase in EGFR expression was observed in patients treated with radical surgery, in patients who received hormonal therapy as primary therapy before radical prostatectomy, and, finally, in patients with metastatic and hormone-refractory disease. It has been proposed that EGFR family receptors and androgen receptors function synergistically in the absence of androgen suggesting cross-talk between the ErbB-2 and androgen receptor pathways, and that mitogen-activated protein kinase and phosphatidylinositol 3-kinase can be considered the transduction pathways. Finally, clinical trials are currently in progress in patients with prostate cancer testing novel agents that selectively interfere with these receptors, such as trastuzumab, an anti- ErbB-2 monoclonal antibody, and gefitinib (ZD1839, Iressa), a small-molecule selective EGFR tyrosine kinase inhibitor.

ErbB-2 signaling is involved in regulating PSA secretion in androgen-independent human prostate cancer LNCaP C-81 cells

The expression and secretion of prostate-specific antigen (PSA) are regulated by androgens in normal prostate secretory epithelial cells. In prostate cancer patients, the serum PSA level is usually elevated and cancer cells are initially responsive to androgens. However, those cancer cells become androgen-independent after androgen ablation therapy. In hormone-refractory cancer patients, even in an androgen-deprived environment, the circulation level of PSA rebounds and is constitutively elevated through a yet unknown mechanism. Tyrosine phosphorylation of ErbB-2 is involved in regulating the androgen-responsive phenotype of prostate cancer cells, and it is at least partly regulated by the cellular form of prostatic acid phosphatase (PAcP), a prostate-unique protein tyrosine phosphatase. We investigated the ErbB-2 signal pathway in androgen-independent PSA secretion. LNCaP C-81 cells, which are androgen-independent LNCaP cells lacking endogenous PAcP expression with a hypertyrosine phosphorylated ErbB-2, secreted a higher level of PSA in conditioned media than did androgen-sensitive LNCaP C-33 parental cells. A restored expression of cellular PAcP in C-81 cells was concurrent with a decrease in tyrophosphorylation of ErbB-2 and reduction of PSA secretion. Moreover, transient transfection of C-33 cells with the wild-type ErbB-2 or a constitutively active mutant of MEK1 cDNA resulted in an increased level of secreted PSA. The elevation of secreted PSA level by the forced expression of ErbB-2 was inhibited by an MEK inhibitor, PD98059. In C-81 cells, the expression of a dominant negative mutant of ErbB-2 reduced the secreted level of PSA. The inhibition of ErbB-2 or mitogen-activated protein (MAP) kinases by specific inhibitors AG879, AG825, or PD98059 led to a decrease in PSA secretion. Taken together, our data clearly indicate that the ErbB-2 signal pathway via MAP kinases (ERK1/2) is involved in regulating the secretion of PSA by androgen-independent human prostate cancer LNCaP C-81 cells in an androgen-depleted environment.

Gene amplification and mRNA and protein overexpression of c-erbB-2 (HER-2/neu) in human intrahepatic cholangiocarcinoma as detected by fluorescence in situ hybridization, in situ hybridization, and immunohistochemistry

BACKGROUND/AIMS

The human proto-oncogene c-erbB-2 (also called HER-2/neu) is located on chromosome 17q21-22. There have been no studies on gene amplification or mRNA expression of c-erbB-2 in human intrahepatic cholangiocarcinoma (CC) hitherto.

METHODS

We investigated c-erbB-2 gene amplification by fluorescence in situ hybridization (FISH), c-erbB2 mRNA expression by ISH, and c-erbB-2 protein expression by immunohistochemistry in 22 archival cases of CC.

RESULTS

FISH revealed that c-erbB-2 gene signals were increased in CC. ISH showed that c-erbB-2 mRNA signals were located in the nuclei and cytoplasms of cancer cells and were increased in cancer cells compared with non-cancerous bile ducts where no signals were present. Immunohistochemistry showed that the c-erbB-2 protein was expressed in the cell membrane of cancer cells, and was increased compared with non-cancerous bile ducts where no expression was found. There was a positive significant correlation between c-erbB-2 mRNA and protein expression. Clinicopathologically, there were no correlations between the c-erbB-2 expression and various pathological features.

CONCLUSIONS

These data suggest that c-erbB-2 gene amplification does occur in CC, and that there is an overexpressed c-erbB-2 protein through the enhanced mRNA expression. The c-erbB-2 gene amplification may be related to the oncogenesis or tumor progression of CC.

HER-2/neu is overexpressed infrequently in patients with prostate carcinoma. Results from the California Cancer Consortium Screening Trial

BACKGROUND

The overexpression of HER-2/neu is found in 20-30% of patients with breast carcinoma and is an adverse prognostic factor. HER-2 overexpression also has been reported in up to 60% of patients with hormone-refractory prostate carcinoma (HRPC) and was correlated with shortened survival. Trastuzumab (Herceptin) is a humanized monoclonal antibody that binds to the HER-2 receptor and has antitumor activity in patients with HER-2-overexpressing breast carcinoma. The authors report the results of HER-2 screening from a Phase II trial of chemotherapy with trastuzumab and docetaxel in patients with HER-2-overexpressing prostate carcinoma.

METHODS

Archival paraffin embedded tumor tissue was obtained from potentially eligible patients and was screened for HER-2 expression by immunohistochemistry (IHC) using a specialized test kit. Shed HER-2 antigen in serum also was determined using an enzyme-linked immunosorbent assay (ELISA). HER-2 gene amplification was assessed by fluorescent in situ hybridization (FISH). Patients with IHC scores of 2+ or 3+ were considered to have HER-2 overexpression and were eligible for the trial. To date, 62 patients with HRPC have been screened.

RESULTS

The median patient age was 72 years, and Gleason scores were < 5 in 1 patients, 5-7 in 24 patients, > 7 in 23 patients, and not specified in 14 patients. IHC HER-2 expression was 0 in 28 patients, 1+ in 14 patients, 2+ in 4 patients, and 3+ in 1 patients. Fifteen patients had either suboptimal tissue (13 patients) for interpretation or had pending results (2 patients). Therefore, 8% of all patients screened (5 of 62 patients) had HER-2 overexpression by IHC. Quantitative ELISA for shed HER-2 was available in 32 patients; this level was elevated (> 15 ng/mL) in only 2 patients, and neither had HER-2 expression by IHC. Of the 5 patients with 2+ or 3+ HER-2 expression by IHC, none had elevated shed HER-2 antigen levels by ELISA. FISH for HER-2 amplification was performed on 12 specimens; 5 of these specimens were uninterpretable due to specimen artifact, and none of the remaining 7 specimens had HER-2 amplification, defined as a ratio > 1. Patient age and Gleason score were not correlated with HER-2 status.

CONCLUSIONS

Unlike breast carcinoma and contrary to prior reports, HER-2 overexpression by IHC in archival prostate tissue from patients who eventually developed hormone-refractory disease was infrequent. There did not appear to be any correlation between HER-2 overexpression by IHC and shed HER-2 antigen levels in serum by ELISA in this tumor type. Whether trastuzumab possesses single-agent activity or modulates chemotherapy response in tumor types other than breast carcinoma remains to be determined.

Signaling inhibitors in the treatment of prostate cancer

Inhibiting androgen receptor (AR) activation through medical or surgical castration and blockade of AR-androgen binding is the cornerstone of treatment for advanced prostate cancer. However, in most cases tumor growth eventually becomes androgen independent. Alternative mechanisms of AR activation, some of which involve growth factor receptor signaling, have been demonstrated in prostate cancer models, and it is likely that a number of autocrine and paracrine growth factor ligand-receptor interactions such as those of epidermal growth factors, fibroblast growth factors, and insulin-like growth factors contribute to the androgen independent phenotype by promoting cell proliferation and survival. Blocking activation and signaling through growth factor receptors and upstream signaling proteins has emerged as a credible approach to cancer treatment. Successful application of this approach in prostate cancer using a growing array of small molecule kinase inhibitors, antibodies, and antisense oligonucleotides will be greatly accelerated by elucidation of the key signaling pathways that maintain the androgen independent phenotype.

Independent prognostic significance of HER-2 oncoprotein expression in pN0 prostate cancer undergoing curative radiotherapy

Existing prognostic algorithms for localized prostate cancer (PC) are hampered by poor validation for endpoints other than biochemical relapse such as clinical disease progression or survival. Therefore, the prognostic relevance of Her-2 (Her-2/neu, c-erbB2) protein expression in patients undergoing curative radiotherapy (RT) was compared to widely accepted prognostic factors such as pretreatment prostate-specific antigen (PSA) levels, biopsy Gleason score and T category of the primary tumor. Biopsies from 112 homogeneously treated patients with T1-4pN0M0 PC were examined by immunohistochemistry and 37% of cases showed membrane-bound Her-2 expression in more than 10% of cancer cells. No definite membrane staining was seen in normal prostate epithelium. With 25 patients dead of PC and a median follow-up of surviving patients of 71 months (range 48-144), the prognostic relevance of Her-2 expression was univariately associated with adverse outcome in terms of biochemical or clinical progression-free survival (B/C-PFS; p = 0.04), clinical progression-free survival (C-PFS; p = 0.02) and disease-specific survival (DSS; p = 0.02). In multivariate analysis, Her-2 expression, T category and Gleason score were independently associated with C-PFS, whereas only Her-2 expression and Gleason score were associated with DSS. Her-2 expression and Gleason score together discriminated 2 groups of patients with 5-year DSS of 95% and 79%, respectively (p < 0.001). Pretreatment PSA levels were associated only with B/C-PFS but not with C-PFS or DSS. Together the data show for the first time that expression of Her-2 is of prognostic relevance in localized PC undergoing RT and suggest that analysis for Her-2 may improve prognostic algorithms for clinically relevant endpoints other than biochemical relapse.

Morphologic and molecular prognostic markers in prostate cancer

In this review, a series of traditional morphology-based measurements, relatively well-documented ancillary biomarkers, and emerging molecular assays are evaluated for their relative ability to predict prognosis in prostate cancer. Prognostic factors that have achieved widespread use and are classified as category I by the College of American Pathologists' Solid Tumor Prognostic Factor Consensus Conference are compared with newer tests that are beginning to be used in clinical practice (category II) and emerging molecular-based assays that have yet to be widely validated in the published literature or in clinical trials (category III).

Her-2/neu oncogene amplification in clinically localised prostate cancer

AIM

To examine the incidence of Her-2/neu oncogene amplification in clinically localised prostate cancer using in situ hybridisation.

METHODS

One hundred and seventeen patients, who had undergone radical prostatectomy, were identified and in situ hybridisation was performed on formalin fixed, paraffin wax embedded tissue using the Quantum Appligene probe for Her-2/neu. The enzyme peroxidase was used to detect the probe because this enabled a permanent record to be kept. Tumours in which there were five or more signals in each nucleus in > 20% of the tumour cells were considered to have a significantly increased copy number. A serial section from these tumours was then hybridised with the chromosome 17 alpha satellite probe. The ratio of the percentage of cells showing an increase in Her-2/neu copy number to the number showing polysomy for chromosome 17 was calculated. A ratio above 2 was considered amplified.

RESULTS

Biochemical recurrence occurred in 50 (43%) patients and 24 (21%) had clinical recurrence. In situ hybridisation for Her-2/neu was accessible in 114 (97%) patients. A significant increase in copy number was present in two patients (1.75 %), but chromosome 17 hybridisation showed that the increase was the result of polysomy rather than true amplification. Both these patients had a Gleason score of 7 and stage T3; they also had recurrent clinical disease with distal metastasis within two and 19 months.

CONCLUSIONS

Increased Her-2/neu oncogene copy number appears to be rare in clinically localised prostatic adenocarcinoma and is related to chromosome 17 polysomy rather than true amplification. As a result, it would not be a useful biomarker for identifying those patients who will have recurrences after radical prostatectomy.

Targeting HER2 in other tumor types

The human epidermal growth factor receptor-2 (HER2) is overexpressed/amplified in a range of tumor types including breast, ovarian, bladder, salivary gland, endometrial, pancreatic and non-small-cell lung cancer (NSCLC). HER2 is implicated in disease initiation and progression, associated with poor prognosis, and may also predict the response to chemotherapy and hormonal therapy. Anti-HER2 monoclonal antibodies (MAbs) have been designed to specifically antagonize the function of the HER2 receptor in HER2-positive tumors. Clinical phase II and III trials have demonstrated the efficacy of the humanized anti-HER2 MAb, trastuzumab (Herceptin), both as a single agent and in combination with chemotherapy in HER2-positive, metastatic breast cancer patients. However, the prevalence of HER2 overexpression/amplification in various tumor types raises the possibility of using anti-HER2 MAbs to antagonize the abnormal function of overexpressed HER2 receptors in HER2-positive tumors other than breast. Preliminary in vitro studies indicate that anti-HER2 MAbs suppress the proliferation of ovarian, gastric and NSCLC cell lines that overexpress the HER2 receptor. These results indicate that anti-HER2 MAbs may have important therapeutic significance in patients presenting with these or other human carcinomas. Clinical trials are either planned or underway to assess the therapeutic role of trastuzumab in NSCLC, bladder and ovarian cancer.

Expression and gene copy number analysis of ERBB2 oncogene in prostate cancer

An anti-ERBB2 antibody, trastuzumab, has been shown to be highly efficient in the treatment of metastatic breast cancers overexpressing the ERBB2 gene. It has been suggested that overexpression and even amplification of ERBB2 may play a role in the development of prostate cancer. Here, we have analyzed gene copy number and expression of the ERBB2 gene in both androgen-dependent primary and metastatic tumors, as well as recurrent hormone-refractory tumors. The expression levels were compared to the expression of ERBB2 in breast cancers with or without ERBB2 gene amplification. Of 126 prostate tumors, chromogenic in situ hybridization (CISH) revealed only 1 case containing borderline (six to eight copies) amplifications of ERBB2. This hormone-refractory tumor, however, did not express ERBB2 protein. Immunohistochemical staining of ERBB2 protein was negative (0 or 1+ intensity) in all prostate samples (n = 124) analyzed. To quantitate the level of ERBB2 mRNA expression in prostate tumors (n = 34) and cell lines (n = 3), as well as in breast tumors (n = 30) and cell lines (n = 16), real-time reverse transcriptase-polymerase chain reaction (LightCycler) methodology was used. The expression level was similar in all prostate tumor types and corresponded to the level of expression in breast carcinomas without ERBB2 amplification. Breast tumors with ERBB2 amplification expressed, on average, approximately 20 times (P < 0.001) higher mRNA levels than prostate tumors or breast carcinomas without the gene amplification. In conclusion, the expression of ERBB2 in prostate cancer is relatively low, and is not altered during disease progression. Thus, it is unlikely that treatment modalities relying on the overexpression of ERBB2 gene will be useful in treating prostate cancer.

Aneusomy of chromosomes 7, 8, and 17 and amplification of HER-2/neu and epidermal growth factor receptor in Gleason score 7 prostate carcinoma: a differential fluorescent in situ hybridization study of Gleason pattern 3 and 4 using tissue microarray

Recent evidence shows that the proportion of poorly differentiated prostate carcinoma (Gleason pattern [GP] 4/5) is a surrogate factor for biochemical failure after radical prostatectomy (RP). However, little is known about specific molecular and cytogenetic changes in this aggressive component of localized prostate cancer. We constructed a tissue microarray containing areas of GP 3 and 4 from formalin-fixed radical prostatectomy specimens of 39 patients with Gleason score 7 carcinoma (>or=50% GP 4), known pathologic staging parameters (stage < T3b), and biochemical failure data (mean follow-up, 30 months; range, 5 to 74 months). Interphase fluorescent in situ hybridization (FISH) was performed on 5-microm microarray sections using pericentromeric probes to chromosomes 7, 8, and 17 and probes for the HER-2/neu and epidermal growth factor receptor (EGFR) genes. Low-level amplification of HER-2/neu was found in 26% of cases (3 to 5 signals per nucleus, corrected for chromosome 17 aneusomy). Aneusomy of chromosomes 7, 8, and 17 was identified in 21%, 15%, and 5% of cases, respectively. All aberrations occurred almost exclusively in GP 4 carcinoma (8 of 8 aneusomies 7, 2 of 2 trisomies 17, 9 of 10 HER-2/neu amplifications, and 5 of 6 aneusomies 8; P < .001). The presence of HER-2/neu amplification was associated with high tumor volume (>2.0 cm(3), P = 0.004). Among patients with negative surgical margins, gain of chromosome 7 was associated with biochemical failure after RP (P =.004, log-rank). Amplification of the EGFR gene occurred in only 1 case (3%). Significant differences in HER-2/neu amplification and gain of chromosomes 7, 8, and 17 were detected between GP 4 prostate carcinoma and GP 3. The frequency of aberrations increased with tumor volume. Chromosome 7 abnormalities may play an important role in cancer progression in margin-negative patients. EGFR amplification was rare, suggesting that this oncogene is not altered at the gene copy number level.

Her-2/neu expression in prostate cancer: high level of expression associated with exposure to hormone therapy and androgen independent disease

PURPOSE

HER-2/neu is a proto-oncogene that encodes a transmembrane receptor belonging to the family of epidermal growth factor receptors. Increasing evidences indicates that HER-2/neu may contribute to hormone resistance in prostate cancer. We investigated HER-2/neu expression in primary, androgen dependent and advanced androgen independent prostate cancer, and its potential value as a marker of disease progression.

MATERIALS AND METHODS

Immunohistochemical testing was performed to investigate HER-2/neu expression in 81 patients with prostate cancer, including 31 with pathological stage C disease treated with radical prostatectomy without preoperative androgen ablation therapy (untreated group), 30 with pathological stage C disease treated before surgery with androgen ablation therapy (treated group) and 20 with advanced androgen independent prostate cancer (androgen independent group). Tumors were classified based on the percent of tumor cells showing HER-2/neu membrane immunoreactivity as low (50% or less) and high (50% or greater) expression.

RESULTS

Of the 31 prostate tumors in the untreated group 9 (29%) showed high HER-2/neu expression versus 15 of 30 (50%) in the treated and 17 of 20 (85%) in the androgen independent groups. The difference in HER-2/neu expression was significant in the untreated and androgen independent (p <0.001) and in the treated and androgen independent (p = 0.016) groups. There was a significant association of Gleason score with HER-2/neu expression in the untreated group (p = 0.038) but not in the treated group. No association was found of tumor substage with HER-2/neu expression. In the untreated group patients with tumors showing high HER-2/neu expression had a decreased survival rate (p = 0.044).

CONCLUSIONS

High HER-2/neu expression is highly associated with exposure to hormone therapy and androgen independence. It may contribute to androgen independence in prostate cancer and identify patients with prostate cancer more likely to have disease progression, particularly those not exposed to previous hormone therapy.

Progressing prostate carcinoma

In the Karnell Cancer Center Grand Rounds, we present a patient who underwent radical prostatectomy with bilateral pelvic lymphadenectomy, but had positive margins and subsequently developed local recurrence and then systemic disease. Pathologic and radiologic aspects of his disease are discussed. Therapeutic options at different stages of the disease are examined from the point of view of the urologist, radiation oncologist, and medical oncologist. The surgical portion of the discussion focuses on the selection of initial therapy. Both the selection of surgical candidates and choice of pre- or post-operative therapy in patients can be aided by prognostic tools looking at several variables, including prostate-specific antigen (PSA) level, Gleason score of the tumor, seminal vesicle invasion, extracapsular invasion, and lymph node involvement. Low-risk patients can be treated with monotherapy, such as radical prostatectomy, external beam radiation therapy, prostate brachytherapy, or cryosurgical ablation of the prostate. Higher risk patients may require adjuvant and possibly neoadjuvant therapy in addition. The radiation portion of the discussion focuses on the use of radiation therapy as salvage for relapsing disease. Of particular importance is the point that treating high-risk patients whose PSA levels have started to rise but are less than 1 ng/ml results in a long-term PSA control rate as high as 75%, but that limiting the use of salvage radiation therapy to patients with high PSA levels or biopsy confirmation of local recurrence in the face of a negative bone scan results in biochemical long-term control of less than 40%. In the medical oncology part of the discussion, the major focus is on the use of chemotherapy to treat patients whose disease has become resistant to hormonal therapy. Mitoxantrone plus a corticosteroid has been found to offer significant palliation for such patients. Combination therapy with estramustine plus taxanes, other microtubule inhibitors, or other agents such as topoisomerase II inhibitors, has been found to cause shrinkage of measurable soft tissue disease and diminution of serum PSA levels. The development of effective hormonal and chemotherapeutic drugs for treatment of metastatic disease has led to new interest in adjuvant and neoadjuvant therapy of high-risk patients.

Expression of androgen receptor coregulatory proteins in prostate cancer and stromal-cell culture models

BACKGROUND

Androgen receptor (AR) transcriptional activity is modulated by cofactor proteins. They act as costimulators, corepressors, or bridging proteins, and a disbalanced expression may contribute to the altered activity of the AR in advanced prostate cancer. We investigated the expression of a series of steroid receptor cofactors in prostate cancer cell lines, including several LNCaP sublines, and in prostate stromal cells.

METHODS

Expression of cofactors was analyzed by means of RT-PCR in PC-3, Du-145, LNCaP, three sublines of LNCaP established after long-term androgen deprivation, and two strains of primary prostate stroma cells. Expression in LNCaP and LNCaP-abl cells (which represented an advanced tumor cell) was analyzed employing semiquantitative RT-PCR.

RESULTS

Ten of the 12 cofactors tested were expressed in all cells analyzed (AIB1, ARA54, ARA70, CBP, cyclin D1, Her2/neu/erbB2, BAG-1/M/L, SRC-1, SMRT, and TIF2). Only ARA55 and FHL2 mRNAs were not detected in all cells. ARA55 mRNA was absent in LNCaP cells, LNCaP sublines, and DU-145 cells; FHL2 was not expressed in LNCaP cells and its derivatives. The expression pattern was identical in LNCaP cells, and the long-term androgen ablated LNCaP sublines. Moreover, comparison of expression levels in LNCaP and LNCaP-abl cells revealed a slight reduction in LNCaP-abl cells but no gross differences.

CONCLUSIONS

Prostatic cells express a great number of steroid receptor cofactors. AR activity thus seems to be modulated in a very complex way in prostate cells.

Fluorescent in situ hybridization study of c-myc oncogene copy number in prostate cancer

We previously conducted a study of 88 cases of prostate cancer in an attempt to identify potential prognostic biomarkers that can distinguish aggressive cases that must be treated immediately. Prostate cancer is a serious disease affecting men worldwide and compromises the quality of life of its patients. Biomarkers studied included chromosome 7 trisomy, chromosome 8 trisomy, and HER-2/neu oncogene amplification. These biomarkers were initially studied because trisomy 8 and oncogene amplification of the HER-2/neu gene have been reported in many other cancers, including those studied in this laboratory. In view of the fact that HER-2/neu amplification was not found to play a prominent role in the group of prostate cancer specimens that we studied, an exploration of other biomarkers was felt to be warranted. Thus, we began a pilot study of c-myc oncogene copy number in prostate cancer using the same protocol for fluorescent in situ hybridization and a direct-labeled SpectrumOrange LSI c-myc probe (Vysis, Inc., Downers Grove, IL) on formalin-fixed, paraffin-embedded tissue. From a total of 36 cases of prostate cancers successfully analyzed, we found 11 (31%) tumors exhibiting 3 or more positive signals for c-myc in 15% or more of the cells. Of these, only 7 tumors (19% of the total cases studied) had >/=3 signals in 20% or more of the cells. No case had >/=3 signals in 25% or more of the cells. Compared to other molecular probes tested, the c-myc signals were more faint and the quality of the preparation was less optimal than other tumor specimens that we previously studied. Based on the information available thus far, we conclude that an increased copy number in c-myc oncogene copy number was not a prominent finding in our cohort of prostate cancer patients.