her-2/neu oncogene expression in prostate carcinoma ... · nancies affecting men worldwide and the...

INTRODUCTION

Prostate cancer is one of the leading malig-

ABSTRACT

The variability in the biological behaviour of prostatecancer and the inadequacy of markers used for asses-sing prognosis cause difficulties in the management ofpatients. We conducted a study of 74 prostate carcino-mas to identify the significance of Her-2/neu oncogenein the initiation and progression of prostate carcinoma.Tissue array blocks were constructed and overexpressi-on of Her-2/neu protein was assessed in areas of carci-noma, low and high grade intraepithelial neoplasia andbenign prostate hyperplasia by immunohistochemistry.Flourescence in-situ hybridization (FISH) method wasused to investigate Her-2/neu gene amplification in are-as of carcinoma of 56 cases. Her-2/neu protein was ex-pressed in a cytoplasmic/membranous manner. The ex-pression rate significantly increased from areas of be-nign prostate hyperplasia to prostatic intraepithelialneoplasia and reached the highest degree in areas ofcarcinoma. Her-2/neu overexpression was observed in72.97% of prostate carcinomas while gene amplificationwas present in 4.05% of the cases. Polisomy or any ot-her anomaly involving chromosome 17 was not detec-ted. There was no relationship between the ratio ofHer-2/neu protein expression or gene amplification andknown prognostic parameters as Gleason grade, andstage of the tumor. The discordance between the ex-pression and amplification rates suggested that expres-sion may be the cause of some other factors rather thantrue gene amplification. According to the results of thepresent study involving mostly the clinically localizedprostate carcinomas, it can be suggested that Her-2/neuoncogene does not seem to have any role in clinically lo-calized prostate carcinoma, but no assessment could bemade for advanced stage carcinomas and the progressi-on to androgen independent disease.

Key words: Her-2/neu, prostate carcinoma, immuno-histochemistry, flourescence in-situ hybridization

ÖZET

Prostat kanserinin biyolojik davran›fl›ndaki de¤iflken-lik ve prognostik belirleyicilerin yetersizli¤i, hastalar›ntakip ve tedavisinde zorluklara neden olmaktad›r. Yet-mifl dört prostat kanseri olgusunu içeren çal›flmam›zda,Her-2/neu onkogeninin kanser bafllang›c› ve ilerleme-sindeki rolünü araflt›rd›k. Doku “array” blo¤u haz›r-land› ve afl›r› Her-2/neu protein ekspresyonu karsinom,düflük ve yüksek dereceli intraepitelyal neoplazi ve be-nign prostat hiperplazisi alanlar›nda de¤erlendirildi.Elli alt› karsinom olgusunda flöresan in-situ hibridizas-yon (FISH) yöntemiyle Her-2/neu gen amplifikasyonuaraflt›r›ld›. Her-2/neu proteini sitoplazmik ve membra-nöz ekspresyon gösterdi. Ekspresyonun benign prostathiperplazisi alanlar›ndan prostatik intraepitelyal neop-lazi alanlar›na gidildikçe art›fl gösterdi¤i ve karsinomalanlar›nda en yüksek düzeye ulaflt›¤› görüldü. Prostatkanseri vakalar›nda Her-2/neu ekspresyon oran›%72.97 iken, gen amplifikasyon oran› %4.05 olaraktespit edildi. Kromozom 17’de polizomi veya baflka her-hangi bir anomali izlenmedi. Her-2/neu protein eks-presyon ve gen amplifikasyon düzeyi ile Gleason skoru,tümör evresi gibi bilinen prognostik parametreler ara-s›nda herhangi bir iliflki izlenmedi. Ekspresyon ve amp-lifikasyon oranlar› aras›ndaki tutars›zl›k, ekspresyo-nun gerçek bir gen amplifikasyonu d›fl› nedenlere ba¤l›olabilece¤ini düflündürdü. Büyük k›sm›n› klinik lokali-ze prostat karsinomu olgular›n›n oluflturdu¤u hastagrubunu içeren çal›flmam›zda sonuçlar, Her-2/neu on-kogeninin klinik olarak lokalize evrede öneminin olma-d›¤›n› düflündürmüfl, ancak daha ileri evreler ve andro-jen ba¤›ms›z faza geçifl ile ilgili yorum yap›lamam›flt›r.

Anahtar sözcükler: Her-2/neu, prostat karsinomu,immünhistokimya, flöresan in-situ hibridizasyon

Her-2/neu oncogene expression in prostate carcinoma: Evaluation of gene amplification by FISH method

Prostat kanserinde Her-2/neu onkogen ekspresyonu: Gen amplifikasyonunun FISH yöntemiyle de¤erlendirilmesi

Duygu KANKAYA1, Ayfle SERTÇEL‹K1, Gülflah KAYGUSUZ1, Ifl›nsu KUZU1, Serpil D‹ZBAY SAK1,Sümer BALTACI2

Ankara University, School of Medicine, Department of Pathology1 and Urology2, ANKARA

Received: 20.02.2008 Accepted: 07.04.2008 Corresponding Author: Duygu Kankaya, M.D., AnkaraUniversity, School of Medicine Department of Pathology, Level01, 06100, Sihhiye, Ankara, Turkey

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Turkish Journal of Pathology 2008;24(2):76-83

nancies affecting men worldwide and the vari-ability in the clinical and biological behaviourof this tumor, the inadequacy of markers usedfor assesing prognosis cause difficulties in themanagement of these patients. Searching fornew prognostic parameters and therapeutic mo-dalities has been the aim of many researches.

Oncogene amplifications are manifestati-ons of genetic instability and have been shownto play a part in the pathogenesis of many can-cers. As a result of gene amplification, increasedproduction of specific proteins leads cancercells to acquire and maintain malignant potenti-al. Her-2/neu gene is a protooncogene which isa member of the EGF receptor family and enco-des a transmembrane receptor protein with tyro-sine kinase activity and involves in normal cellgrowth. Her-2/neu protooncogene shows onco-genic conversion via gene amplification andprotein overexpression which leads to abnormalproliferation and agressive behaviour of tumorcells (1,2).

Recently there has been a growing interestin Her-2/neu oncogene, expression / amplificati-on which has been shown to correlate with ashorter survival in a variety of epithelial malig-nancies (3-7).

Since new therapeutic modalities are nowavailable that specifically target Her-2/neu on-cogene, diagnostic tests for identifying Her-2/neu oncoprotein have been used as routineapplication in the management of breast cancerpatients.

There are many studies reported in the li-terature investigating the role of Her-2/neu on-cogene in prostate carcinomas which have pro-vided contradictory results. This study was per-formed to test the hypothesis that Her-2/neu on-cogene might have a role in the initiation andprogression of prostate carcinomas.

MATERIALS and METHODS

Patient selection and tissue array construc-tion:

The study included materials from 74 pati-ents with prostate cancer who underwent radicalprostatectomy with bilateral pelvic lymph nodedissection at the urology department of AnkaraUniversity School of Medicine between 1993and 2002. Hematoxylin and eosin stained histo-logical sections from formalin fixed, paraffinembedded tissues were reviewed and histologi-cal grade was determined according to the Glea-son system. Representative areas were selectedfor each tumor specimen and tissue array (TA)blocks were constructed by taking cores of 4mm in diameter from these areas using punchbiopsy needle. Two 6 cores (average 3.7 coresper case) were taken from each tumor specimen.Twenty three TA blocks, each containing 12 co-res were obtained. Four-micrometer sections ofthese array blocks were cut and placed on char-ged slides. Three sections, one for Hematoxylin-eosin, one for immunohistochemistry, and onefor flourescence in-situ hybridization were ob-tained from each TA block. Hematoxylin-eosinstained sections were used for histological veri-fication of areas of benign prostate hyperplasia(BPH), low grade prostatic intraepithelial neop-lasia (LGPIN), high grade prostatic intraepithe-lial neoplasia (HGPIN) and prostatic carcinoma.According to the Gleason grade system, onegrade was determined in each core of the casesand the most frequent grade among the cores ofthe same case was defined as “dominant grade”and considered as the representative Gleasongrade of the case. The highest Gleason gradeamong the cores was defined as the “maximumgrade”.

Immunohistochemistry (IHC):Sections (4 mµ) were deparaffinized and

antigen retrieval was performed by immersingslides in 10 mmol/L citrate buffer (ph=6) andheating in a 95°C water bath for 20 minutes. Af-ter application of hydrogen peroxide for 5 minu-tes, the slides were incubated with primary anti-body which was a polyclonal rabbit anti-humanHER2/neu antibody recognizing an intracellular

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domain of Her-2/neu oncoprotein (DAKO, Den-mark, Code No: A 0485) (1/300 dilution) for 20minutes. Then slides were incubated with biotinfor 10 and with streptavidin for 10 minutes res-pectively. This was followed by immersion insubstrate-chromogen solution for 8 minutes.Hematoxylin was used for counterstaining. Sec-tions from a breast cancer specimen, which wasknown to be 3+ positive for Her-2/neu, wereused as positive controls.

Both cytoplasmic and membranous stai-ning were evaluated in the areas of cancer,LGPIN, HGPIN and BPH in each core and sco-red according to the intensity and the percenta-ge of stained cells. Intensity was scored on a 0to 3+ scale (0: no staining, 1: weak, 2: modera-te, 3: strong staining). The percentage of stainedcells was evaluated on a 0 to 3+ scale (for mem-branous staining: 0: no staining, 1+:1-5%, 2+:6-20% and 3+:21-100%; for cytoplasmic staining:0: no staining, 1+:1-30%, 2+:31-80%, 3+:81-100%). Cytoplasmic staining score (CSS) andmembranous staining score (MSS) were calcu-lated separately by adding the intensity and per-centage scores, and the total staining score(TSS) in each core was determined by addingCSS and MSS. The highest staining score (CSS:0-6, MSS: 0-6, TSS: 0-12) among the cores ofthe same case was accepted as the representati-ve staining score of the case.

Flourescence in-situ hybridization (FISH):Her-2/neu gene amplification was investi-

gated in 56 of 74 prostate carcinomas by FISHand for each case 1-3 cores were evaluated. De-paraffinisation, sequential acid incubation, de-naturation, proteinase K digestion steps werefollowed respectively. After formamide denatu-ration and formalin fixation, the slides weredehydrated in graded ethyl alcohol and air dried.FISH was performed on pretreated slides usingQ-BIOgene Chromosome 17p12 (HER2/NE-U)/Alphasatellite 17 Cocktail (dual color) TMFISH probe (Cat. #: PONC1712). After hybridi-zation, nuclei were stained with 6-diamidin 2-

fenilindiol dihydrochloride antifade solution(DAPI) and the signals were visualized on a ZE-ISS Axiscope fluorescence microscope. Onlythe cells with at least one red and one green sig-nal in their nuclei were evaluated. Red (Her 2)and green (Chromosome 17) signals were coun-ted in 40 non-overlapping tumor nuclei in eachcore and the ratio of red and green signals wasdefined as the amplification score. Cores withan amplification score of >2 or with tight cluste-ring signal pattern in ≥50% of counted cells we-re considered as positive for Her-2/neu geneamplification. The highest amplification scoreamong the cores of the same case was acceptedas the representative amplification score of thecase.

Statistical Analysis:“Kruskal Wallis Test”, Mann Whitney

test”, “Student’s T test”, “Chi Square test”,“Spearmen’s Correlation test” were used for sta-tistical analysis. All analyses were performedusing Statistica software and a p value of <0.05was considered as statistically significant.

RESULTS

PatientsThe mean age of the patients was 62.41

(±5.6) years. 10, 42, 14, 8 patients were stagesT2a, T2b, T3a, T3b, respectively. They were N0except for 2 of them and 3 of them had bone me-tastasis. The mean preoperative PSA value was12.48 ng/ml (±9.72). Follow up periods of the74 patients ranged from 9 to 60 months. Bioche-mical recurrence occurred in 3 patients (definedas a serum PSA of greater than 0.4 ng/lt). Threeof the patients with metastasis had received an-tiandrogen therapy at 1 month after the surgery.All of them responded initally but had develo-ped androgen independent disease after the me-dian time of 40 months. The preoperative PSAlevels significantly correlated with the stage ofthe tumor (p=0.05) and Gleason grade (p=0.05).

Histopathology, Immunohistochemistry

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and FISH:The distribution of cases according to

Gleason grade is shown in Table 1. Of the 74 prostate cancers, 54 (%72.97)

showed immunostaining, only in cytoplasmic(n=34; 45.94%), membranous (n=6; 8.1%) inmixed (cytoplasmic and membranous) patterns(n=14; 18.91%) respectively (Fig. 1). No corre-lation between immunostaining scores and stageof the tumor was found (p=2.91).

There was no statistically significant asso-ciation between immunostaining scores and do-minant or maximum Gleason grade and pati-ents’ ages or preoperative PSA levels as well.

Immunostaining was compared in areas ofBPH, LGPIN, HGPIN and prostatic carcinoma.The percentage of cores with only cytoplasmicor mixed (cytoplasmic and membranous) immu-nostaining patterns significantly increased fromareas of BPH to PIN and reached the highestdegree in areas of prostatic carcinoma (Chi-Square test, p=0, p=0); whereas no such correla-

Figure 1. Examples of Her-2/neu expression. a. LGPIN, membranous (+1) (x100), b. LGPIN, cytoplasmic (+1) (x100), c. HGPIN,membranous (+2) (x100), d. HGPIN, cytoplasmic (+2) (x100), e. Gleason grade 3 prostate carcinoma, membranous (+2) (x100), f.Gleason grade 3 prostate carcinoma, cytoplasmic (+2) (x40).

Table 1. Distribution of cases according to the dominant andmaximum Gleason grade.

Gleason Grade

Dominant gradeMaximum grade

3 (n, %)

35 (47.3)23 (31.1)

4 (n, %)

37 (50)42 (56.8)

5 (n, %)

2 (7.2)9 (12.2)

a b

c d

e f

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tion was found for cores with only membranousstaining (Table 2).

The percentage of immunostaining (incytoplasmic or membranous pattern) was com-pared between cores with different Gleason gra-des. The relationship between Gleason gradeand the percentage of immunostained cores wasinvestigated among the total number of 254 co-res representing 74 patients. There was no rela-tionship between Gleason grade and Her-2/neuprotein expression.

The percentages of immunostained cores(in cytoplasmic or membranous pattern) werecompared between groups with different Glea-son grades. There was no relationship betweenGleason grade and Her-2/neu protein expressi-on.

In 56 of the 74 cases, a minimum of 40 tu-mor cells with at least one CEP17 and one Her2Neu signal could be detected in one or more co-

res stained with FISH. Gene amplification wasdetected in only 3 tumors, one of which belon-ged to a patient with androgen independent di-sease (Fig. 2). Of the 3 FISH positive cases, inonly one with a score of +1 was present Therewas no association between amplification scoreand dominant or maximum Gleason grades(p=0.291, p=0.513, respectively) or betweenamplification score and immunostaining scores(p=0.864, p=0.521, respectively).

DISCUSSION

Studies using immunohistochemistry toinvestigate Her-2/neu oncoprotein expression inprostate carcinomas have given contradictoryand confusing results with a reported expressionrate of 0% to 100% (8-11).

Some studies detected Her-2/neu overex-pression in prostate carcinomas and found cor-

Figure 2. Her-2/neu gene amplification by FISH (green / red signals >2).

Table 2. The percentage of immunostained cores in areas of BPH, PIN and carcinoma.

Cancer (n=254 cores)HGPIN (n=55 cores)LGPIN (n=13 cores)BPH (n=117 cores)

Cytoplasmic staining (n, %)

112 cores (44.09)21 cores (38.18)5 cores (38.46)

14 cores (11.96)p=0

Membranousstaining (n, %)

19 cores (7.48)6 cores (10.9)2 cores (15.38)4 cores (3.41)

p=0.168

Membranous andcytoplasmic staining

(n, %)

12 cores (4.72)24 cores (43.6)5 cores (38.46)

16 cores (13.67)p=0

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relation with Gleason grade, tumor stage andaneuploidy (9,12-14), whereas no such correla-tion was found in some of them (8,11).

Technical factors as the type of examinedtissue, fixation, staining protocols, antigen ret-rieval procedures, the type of anti-Her2 antibo-dies, heterogeneity in case selection and scoringsystems may be responsible for this disparity(15,16). The most frequently observed immuno-histochemical staining pattern was cytoplasmicrather than membranous. The cytoplasmic im-munostaining may be explained by the bindingof antibody to the intracellular part of Her-2/neutransmembrane protein. Ross et al. (12), foundsignificant correlation between Her-2/neucytoplasmic immunostaining intensity and tu-mor grade or aneuploidy status. Differentialstaining of Her-2/neu in different subcellular or-ganelles may be related to cancer stages and celltypes (17). In the present study, the frequency ofmembranous immunostaining inversely correla-ted with Gleason grade and no membranous im-munostaining was seen in the areas of grade 5carcinoma. Compatibly, Kameda et al. (18) haspreviously reported that Her-2/neu immunore-activity in cells of poorly differentiated gastrictumors was detected most often within thecytoplasm, whereas the immunoreactivity inwell differentiated tumor cells was detected onthe cell membranes. However, Her-2/neu ex-pression detected by Western blotting was verylow or none in the cytoplasmic positive tumorcells. This finding suggests that cytoplasmicstaining may be a non-specific finding. Alterna-tively there may be an error preventing themembranous localization of the protein.

The significant increase of Her-2 overex-pression from areas of BPH to PIN and carcino-ma may indicate that Her-2/neu oncoprotein isinvolved in growth stimulation and oncogenictransformation of prostatic cells. However, therole of Her-2/neu expression in the progressionof prostate carcinoma is argueable, since no cor-relation with known prognostic parameters suchas Gleason grade, stage of tumor was detected.

Our results are compatible with a previouslypublished report which suggested that Her-2/neu oncoprotein may be involved in the initialneoplastic transformation but its contribution intumor progression may probably be more limi-ted (19).

According to the studies performed usingFISH, one group has found amplification of theHer-2/neu oncogene in up to 44% of the cases,and this was associated with advanced patholo-gical stage and higher Gleason score. However,more recent work by that group showed a loweramplification rate of 10-25% (20-22). Anotherstudy on different stages of prostate carcinoma-from localised to metastatic- found no amplifi-cation at any stage (23). The differences in amp-lification rates in these studies might be due tothe definition of amplification used by the diffe-rent investigators or increase in gene copy num-bers due to chromosome 17 polysomy whichmight be mistaken for true amplification. In ourseries, most of the cases were clinically locali-zed prostate cancer, Her-2/neu gene amplificati-on was present only in 4.05%, in spite of an ove-rexpression rate of 72.97%. Polisomy or any ot-her anomaly involving chromosome 17 was notdetected in any of cases which might be respon-sible for high Her-2/neu protein expression. Thediscordance between the expression and ampli-fication of Her-2/neu oncogene suggests thatHer-2/neu oncoprotein expression may not beassociated with Her-2/neu gene amplificationwhich makes it difficult to comment on the sig-nificance of Her-2/neu protein expression in thedevelopment of prostatic carcinoma. We are inthe same opinion with Zhau et al. (17) who sug-gested that the underlying mechanism for higherHer-2/neu protein expression might be due toincreased rate of Her-2/neu transcription, in-creased Her-2/neu mRNA stability, posttrans-criptional processing, or all of them.

It has been suggested that Her-2/neu amp-lification was rare in clinically localized prosta-te carcinoma (24). Her-2/neu oncogene amplifi-cation/overexpression has been shown to be as-

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sociated with the progression of prostate cancerfrom an androgen dependent to an androgen in-dependent phenotype. Higher expression ofHer-2/neu has been detected in androgen refrac-tory and metastatic prostate carcinomas, in con-trast to early stages (25-29). This finding led tothe use of a monoclonal antibody targeting Her-2/neu in the treatment of androgen refractorycarcinoma (30), however trials showed that ithad a poor efficacy as a single agent (31). Be-cause nearly all prostate carcinomas included inthis study were clinically localized and only fi-ve of them were in hormone refractory state, wecannot comment on the significance of Her-2/neu oncoprotein in the progression of andro-gen dependent to androgen independent phe-notype.

In conclusion, the significant increase ofHer-2 overexpression from areas of BPH to PINand carcinoma may indicate that Her-2/neu on-coprotein is involved in stimulation of thegrowth and oncogenic transformation of prosta-tic cells. However, the role of Her-2/neu expres-sion in the progression of prostate carcinoma isargueable, since no correlation with knownprognostic parameters such as Gleason grade,stage of tumor was detected. Furthermore, thediscordance between the expression and ampli-fication rates of Her-2/neu oncogene suggeststhat Her-2/neu oncoprotein expression may notbe associated with true gene amplificationwhich makes it difficult to comment on the sig-nificance of Her-2/neu protein expression inprostate carcinoma. We think that some otherfactors such as increased rate of Her-2/neutranscription, posttranscriptional processingmay be the underlying mechanism for high Her-2/neu protein expression in prostate cancer. Ourlimitation was that most of the patients includedin this study had clinically localized prostatecancer and no assesment could be made on thesignificance of Her-2/neu oncoprotein in theprogression of carcinoma to the androgen inde-pendent phenotype. Therefore, studies on largerseries of prostate carcinoma representing diffe-

rent stages are necessary to determine whetherHer-2/neu gene has a role in prostate carcinoma.

REFERENCES

1. Hung MC, Schechter AL, Chevray PY, Stem DF, We-inberg RA. Molecular cloning of the neu gene: Absen-ce of gross structural alteration in oncogenic alleles.Proc Natl Acad Sci USA 1986; 83:261-264.

2. Hynes NE, Stern DF. The biology of erbB-2/neu: Her-2 and its role in cancer. Biochem Biophys Acta RevCancer 1994; 1198:165-184.

3. Press MF, Bernstein L, Thomas PA, Zhou JY, Ma Y,Hung G, et al. Her-2/neu gene amplification characte-rized by flourescence in situ hybridization: poor prog-nosis in node-negative breast carcinomas. J Clin Oncol1997;15: 2894-2904.

4. Saffari B, Jones LA, el-Naggar A, Felix JC, George J,Press MF. Amplification and overexpression of Her-2/neu (c-erbB2) in endometrial cancers: correlationwith overall survival. Cancer Res 1995;55: 5693-5698.

5. Ranzani GN, Pellegata NS, Previdere C, Saragoni A,Vio A, Maltoni M, Amadori D. Heterogeneous proto-oncogene amplification correlates with tumor progres-sion and presence of metastasis in gastric cancer pati-ents. Cancer Res 1990; 50: 7811-7814.

6. Press MF, Pike MC, Hung G, Zhou JY, Ma Y, GeorgeJ, et al. Amplification and overexpression of Her-2/ne-u in carcinomas of the salivary gland: correlation withpoor prognosis. Cancer Res 1994; 54: 5675-5682.

7. Zhau HE, Zhang X, von Eschenbach AC, Scorsone K,Babaian RJ, Ro JY, Hung MC. Amplification and ex-pression of the c-erbB2/neu proto-oncogene in humanbladder cancer. Mol Carcinogen 1990;3:254-257.

8. Visokarpi T, Kallioniemi OP, Koivula T, Harvey J,Isola J. Expression of epidermal growth factor receptorand erbB2 (Her2/neu) oncoprotein in prostatic carcino-mas. Mod Pathol 1992; 5: 643-648.

9. Sadasivan R, Morgan R, Jenning S, Austenfeld M, VanVeldhuizen P, Stephens R, Noble M. Overexpressionof HER-2/neu may be an indicator of poor prognosis inprostate cancer. J Urol 1993; 1993:126-131.

10. Cohen RJ, Cooper K, Haffejee Z, Robinson E, BeckerPJ. Immunohistochemical detection of oncogene prote-ins and neuroendocrine differentiation in different sta-ges of protate cancer. Pathology 1995; 27: 229-232.

11. Lara PN Jr, Meyers FJ, Gray CR, Edwards RG, Gu-merlock PH, Kauderer C, et al. HER-2 / neu is overex-pressed infrequently in patients with prostate carcino-ma. Results from the California Cancer ConsortiumScreening Trial. Cancer 2002 May 15; 94: 2584-2589.

12. Ross JS, Nazeer T, Church K, Amato C, Figge H, Rif-kin MD, et al. Contribution of HER-2/neu oncogeneexpression to tumor grade and DNA content analysis inthe prediction of prostatic carcinoma and metastasis.Cancer 1993; 72: 3020-3028.

13. Epstein JI, Amin M, Boccon-Gibod L, Egevad L,Humphrey PA, Mikuz G, et al. Prognostic factors andreporting of prostate carcinoma in radical prostatec-tomy and pelvic lymphadenectomy specimens. Scand JUrol Nephrol Suppl. 2005;216:34-63.

82


14. San Miguel Fraile P, Dos Santos JE, Pélaez Boismo-rand E, Ortiz Rey JA, Iglesias Rodríguez B, Cambro-nero Santos J, et al. Expression of the cerbB-2 (HER-2/neu) oncoprotein in prostatic adenocarcinoma. ActasUrol Esp 2005; 29:64-69.

15. Ware JL, Maygarden SJ, Koontz WW, Strom SC. Im-munohistochemical detection of c-erbB-2 protein inhuman benign and neoplastic prostate. Hum Pathol1991; 22: 254-258.

16. Sanchez KM, Sweeney CJ, Mass R, Koch MO, EckertGJ, Geary WA, et al. Evaluation of HER-2/neu expres-sion in prostatic adenocarcinoma: A request for a stan-dardized, organ spesific methodology. Cancer 2002;95:1650-1655.

17. Zhau HE, Wan DS, Zhou J, Miller GJ, et al. Expressi-on of c-erbB2/ neu protooncogene in human prostaticcancer tissues and cell lines. Mol Carcinog 1992;5:320-327.

18. Kameda T, Yasui W, Yoshida K, Tsujino T, Nakaya-ma H, Ito M, et al. Expression of ERBB2 in humangastric carcinomas: relationship between p185ERBB2expression and the gene amplification. Cancer Res1990; 50: 8002-8009.

19. Gu K, Mes-Masson A, Gauthier J, Saad F. Overexpres-sion of Her-2/neu in human prostate cancer and benignhyperplasia. Cancer Letters 1996; 99: 185-189.

20. Ross JS, Sheehan CE, Hayner-Buchan AM, AmbrosRA, Kallakury BV, Kaufman RP Jr, et al. Prognosticsignificance of Her-2/neu gene amplification status byfluorescence in situ hybridization of prostate carcino-ma. Cancer 1997; 79: 2162-2170.

21. Ross JS, Sheehan C, Hayner-Buchan AM, AmbrosRA, Kallakury BV, Kaufman R, et al. Her-2/neu geneamplification status in prostate cancer by fluorescencein situ hybridization. Hum Pathol 1997;28: 827-833.

22. Kallakury BV, Sheehan CE, Ambros RA, Fisher HA,Kaufman RP Jr, Muraca PJ, Ross JS. Correlation ofp34cdc2 cyclin-dependent kinase overexpression,

CD44s downregulation, and Her-2/neu oncogene amp-lification with recurrence in prostatic adenocarcino-mas. J Clin Oncol 1998;16:1302-1309.

23. Bubendorf L, Kononen J, Koivisto P, Schraml P, MochH, Gasser TC, et al. Survey of gene amplifications du-ring prostate cancer progression by high-throughputfluorescence in situ hybridization on tissue microar-rays. Cancer Res 1999;59:803-806.

24. Oxley JD, Winkler MH, Gillatt DA, and Peat DS. Her-2/neu oncogene amplification in clinically localisedprostate cancer. J Clin Pathol 2002; 55:118-120.

25. Arai Y, Yoshiki T, Yoshida O. C-erbB2 oncoprotein: apotential biomarker of advanced prostate cancer. Pros-tate 1997; 30: 195-201.

26. Morote J, de Torres I, Caceres C, Vallejo C, SchwartzS Jr, Raventos J. Prognostic value of immunohistoche-mical expression of the c-erbB2 oncoprotein in metas-tatic prostate cancer. Int J Cancer 1999; 84:421-425.

27. Craft N, Shostak Y, Carey M, Sawyers C: A mecha-nism for hormone independent prostate cancer throughmodulation of androgen receptor signaling by theHer2/neu tyrosine kinase. Nat Med 1999; 5:280-285.

28. Signoretti S, Montironi R, Manola J, Altimari A, TamC, Bubley G, et al: Her-2/neu expression and progres-sion toward androgen independence in human prostatecancer. J Natl Cancer Inst 2000; 92: 1918-1925.

29. Montironi R, Mazzucchelli R. HER-2 expression andgene amplification in high-grade PIN and prostate can-cer. Arch Ital Urol Androl 2006;78:135-139.

30. Agus DB, Bunn PA Jr, Franklin W, Garcia M, OzolsRF. HER-2/neu as a therapeutic target in non-smallcell lung cancer, prostate cancer, and ovarian cancer.Semin Oncol 2000; 27(6 Suppl 11):53-63; discussion92-100.

31. Ziada A, Barqawi A, Glode LM, Varella-Garcia M,Crighton F, Majeski S, et al. The use of trastuzumab inthe treatment of hormone refractory prostate cancer;phase II trial. Prostate 2004; 60:332-337.

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