Immunohistochemical and UltrastructuralFeatures of Neuroendocrine Differentiated

Carcinomas of the Prostate: AnImmunoelectron Microscopic Study

Daisaku Hirano, MD

Department of Urology, Nihon

University School of Medicine,

Tokyo, Japan

Toyoharu Jike

Electron Microscope Division,

Nihon University School of

Medicine, Tokyo, Japan

Yasuhiro Okada, MD,

Sadatsugu Minei, MD, Shuji

Sugimoto, MD, Kenya

Yamaguchi, MD, Tetsuo

Yoshikawa, MD, Takahiko

Hachiya, MD, Toshio Yoshida,

MD, and Yukie Takimoto, MD

Department of Urology, Nihon

University School of Medicine,

Tokyo, Japan

ABSTRACT The purpose of this study was to further define the immunohis-

tochemical and ultrastructural characteristics of neuroendocrine (NE) differ-

entiated prostatic carcinomas. Seventy-seven specimens were obtained from

prostatic carcinoma tumors during prostatectomy, transurethral resection of

prostate or biopsy in 77 prostate cancer patients, and analyzed by immuno-

histochemical staining for chromogranin A (CgA). Nine of these tumors were

also studied by elctron microscopy and 4 were examined by pre-embedding

immunoelectron microscopy. CgA-stained cells were detected in 36 tumors

(47%). Clinically advanced tumors or tumors with higher histological grades

were associated with increased NE differentiation. Three of the tumors stud-

ied by electron microscopy contained cells showing unequivocal NE differ-

entiation revealed by the presence of neurosecretory granules, while the

poorly NE-differentiated malignant cells contained pleomorphic granules,

which were lysosomal-like rather than NE-type granules. Immunoelectron

microscopy demonstrated the presence of CgA immunoreactivity on the

pleomorphic granules in the poorly differentiated malignant glands. This

study suggests that NE-differentiated malignant cells in prostate cancer

tissues may induce aggressive behavior in adjacent proliferating neoplastic

cells via a paracrine mechanism.

KEYWORDS immunoelectron microscopy, immunohistochemistry, neuroen-

docrine differentiation, prostate cancer, ultrastructure

Small-cell prostate carcinomas or carcinoid-like tumors represent only 1–2%

of all prostate malignancies and are characterized as pure neuroendocrine

(NE) tumors [1]. However, NE-differentiated cells are also detected immuno-

histochemically in the normal prostate, in benign prostatic hyperplasia, and

in common prostatic adenocarcinoma, and approximately 10% of common

prostatic carcinomas have extensive and multifocal NE features [2, 3]. These

NE-differentiated prostatic carcinomas are similar to small cell carcinomas of

Received 16 February 2005;accepted 21 February 2005.

Address correspondence to DaisakuHirano, MD, Department of Urology,Nihon University School of Medicine,30-1 Ooyaguchi Kamimachi Itabashi-ku, Tokyo, 173-88610, Japan. E-mail:byd04561@nifty.com

Ultrastructural Pathology, 29:367–375, 2005Copyright # Taylor & Francis Inc.ISSN: 0191-3123 print=1521-0758 onlineDOI: 10.1080/019131290945718

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the lung, with comparable immunoreactivity and the

presence of neurosecretory granules on electron

microscopy [2, 3], and comprise a highly specialized

cell population containing neurosecretory granules

rich in various peptide hormones and biogenic

amines, such as chromogranin A (CgA) [3], serotonin

[4], bombesin [5], vascular endothelial growth factors

[6], and somatostatin [7]. di Sant’ Agnese and Cockett

[2] suggested that these regulatory peptides, which

may act through lumencrine, endocrine, paracrine,

and autocrine mechanisms, are probably involved

in normal growth, differentiation, and secretory func-

tions of the gland. However, the precise biological

behavior of NE-differentiated carcinomas in the com-

mon prostate cancer tissues is not understood.

Therefore, we have further studied the clinicopatho-

logical features of the NE-differentiated prostatic

carcinomas in the common prostate cancer, by

immunostaining for a specific NE marker, CgA, and

by assessment of their ultrastructural characteristics.

In addition, we used immunoelectron microscopy

to confirm the presence of substantial quantities of

CgA in the neurosecretory granules of NE-differen-

tiated prostatic carcinoma cells.

MATERIALS AND METHODS

Patients and Specimens

Specimens of prostatic carcinoma from 77 patients

were studied, of which 72 were obtained from rad-

ical prostatectomy, 1 during transurethral resection

(TUR) of prostate, and 4 during prostate biopsy.

Patient characteristics are given in Table 1. Clinical

stage and pathological grade of prostate cancer were

definedaccording to theWhitmore-Jewett classification

[8] and the WHO grading system [9], respectively.

All patients gave informed consent that their pros-

tatic specimens from surgical extirpation or biopsy

could be used in this study. All specimens were

evaluated for NE differentiation by immunohisto-

chemical staining for CgA. Nine specimens were

further studied by electron microscopy and 4 speci-

mens were studies by immunoelectron microscopy.

Immunohistochemical Analysis

Each prostate specimen obtained at radical prosta-

tectomy, TUR, or biopsy was fixed in 10% buffered

formalin by conventional methods. After fixation,

the gland obtained from radical prostatectomy was

step-sectioned at 5-mm intervals perpendicular to

the urethra and embedded in paraffin. The most cen-

tral parts of the radical prostatectomy and TUR speci-

mens with representative tumor growth, as indicated

by hematoxylin and eosin staining, were chosen for

immunohistochemistry. Each 4-mm section was

deparaffinized and incubated in 1% H2O2 in meth-

anol for 20min at room temperature to block

endogenous peroxidase activity. The sections were

then washed in phosphate-buffered saline (PBS),

pH 7.4, preincubated with 10% bovine serum albu-

min for 20min at 37�C, and incubated for 2 h at room

temperature with rabbit anti-human CgA antibody

(Dako, Carpinteria, CA, USA) diluted 1:250. After

washes in PBS, the sections were incubated with

avidin–biotin conjugated mouse anti-rabbit immuno-

globulins (Dako) for 30min at room temperature.

After washes in PBS, the section was incubated with

0.03% 3,30-diaminobenzidine tetrahydrochloride

(Wako, Osaka, Japan) in buffer containing hydrogen

peroxide. Nuclei were counterstained with hematox-

ylin, and the sections were dehydrated and cover-

slipped.

Positive controls included NE cells from adjacent

benign prostatic tissues and NE cells from pancreatic

tissues. For negative controls, appropriately diluted

nonimmune serum was substituted for anti-CgA

antibody.

Tumors were evaluated for positive CgA staining

in all neoplastic lesions using a gridded eyepiece at

200�magnification, and scored as follows: 0 ¼ no

immunoreactive tumor cells; þ1 ¼ <10% immunore-

active neoplastic cells; þ2 ¼ 10–20% immunore-

active tumor cells; þ3 ¼>20% immunoreactive

neoplastic cells.

TABLE 1 Patient Characteristics

Median age (range) (years) 69 (50–78)

Clinical stage (%)

T1b, T1c 22 (29)

T2 26 (34)

T3 24 (31)

Distant metastases 5 (6)

Histological grade (%)

Wel 16 (21)

Mod 40 (52)

Por 21 (27)

D. Hirano et al. 368

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Electron Microscopy

Portions of the specimens obtained by surgical

extirpation or biopsy were immediately cut into 1-

mm blocks and placed in 2% glutaraldehyde in

0.2M cacodylate buffer (pH 7.4) for 2 h. The blocks

were postfixed in 1% buffered osmium tetroxide

for 1 h, dehydrated in graded alcohol, and embedded

in Epon 812. Semithin sections were cut and

observed by light microscopy to locate relevant areas

for electron microscopic examination. This sections

were cut with a diamond knife, using a LEICA Ultra-

tome UCT, stained with uranyl acetate and lead

citrate, and examined using an electron microscope

model 1200EX-II, JEOL, Tokyo, Japan.

Pre-embedding Immunoelectron

Microscopy

Portions of specimens obtained at surgery were

immediately placed in 4% paraformaldehyde, cut

into 50-mm-thick sections on a vibratome, and fixed

overnight. The sections were incubated in 3%

H2O2 in methanol for 30min at room temperature

to block endogenous peroxidase activity, and for

1 h with Dako Protein Block to prevent nonspecific

staining. The sections were incubated overnight with

rabbit anti-human CgA antibody diluted 1:250,

washed, and incubated with EnVision labeled

polymer-HRP anti-rabbit IgG (Dako) for 2 h. Immuno-

reactivity was visualized with 0.03% 3,30-diamino-

benzidine tetrahydrochloride as above. The sections

were then placed in 2% glutaraldehyde for 2 h, post-

fixed in 1% osmium tetroxide for 1 h, dehydrated in

graded alcohol, flatly embedded in Epon 812, and

mounted on glass slides.

Immunoreactive prostatic carcinoma cells were

located by light microscopy and relevant sections

were attached to conventional Epon 812 block, cut

with a diamond knife, and examined without uranyl

acetate and lead citrate by electron microscopy as

above.

Statistical Analysis

Associations between clinicopathological charac-

teristics and NE differentiation were analyzed for

statistical significance using the Mann-Whitney U test

and Kruskal-Wallis rank test with StatView software

(Abacus Concepts, CA, USA). All calculated p

values < .05 were considered statistically significant.

RESULTS

Immunohistochemical Analysis

Examination of the morphological features of

immunoreactive neoplastic cells indicated that in

well-differentiated tumors, NE differentiation was

most highly concentrated in scattered CgA-stained

areas or occasionally in individual CgA-positive cells;

in moderately differentiated tumors, including those

with a cribriform pattern, NE differentiation was

mostly found in focal or clustered NE neoplastic

cells; while in poorly differentiated tumors it was

mostly associated with diffuse NE cells (Figure 1).

CgA-positive tumor cells were found in 36 of the

77 specimens (47% of the patients). The staining

scores for immunoreactive cancer cells were þ1,

þ2, and þ3 in 28, 6, and 2 specimens, respectively.

CgA staining of the tumor cells was not observed in

the remaining 41 specimens (53% of the patients).

Analysis of the correlation between NE differen-

tiation and clinical stage indicated that the median

staining scores were 0 in disease that was organ-

confined clinically (stage B or less), and þ1 in

advanced disease (stage C or more). The CgA

staining scores were significantly higher in the

advanced tumors ( p < .003) (Figure 2). Analysis of

the relationship between NE differentiation and

histological grades indicated that the median staining

scores were 0 in well to moderately differentiated

tumors, and þ1 in poorly differentiated tumors.

The CgA staining scores were significantly higher

in tumors with the highest histological grade

( p < .04) (Figure 3).

Electron Microscopy

Electron microscopy revealed cells with unequivo-

cal NE differentiation in two radical prostatectomy

and one TUR specimens. The malignant NE cells

contained numerous neurosecretory granules such

as a variable number of dense-core-bound granules.

In the well-differentiated malignant glands, the api-

cal cytoplasm of the NE cells contained relatively

small and uniform dense core granules ranging from

200 to 600 nm. Some granules excreting into the

lumen were observed (Figure 4). Other organelles

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such as the endoplasmic reticulum, Golgi apparatus,

and mitochondria were scattered in the cytoplasm. In

the cribriform pattern of the moderately differen-

tiated malignant glands, NE malignant cells clustered,

as observed by light microscopy, and had relatively

pleomorphic neurosecretory granules ranging from

120 to 770 nm (Figure 5). In the poorly differentiated

malignant glands, NE neoplastic cells contained

pleomorphic granules ranging from 20 to 600 nm;

these were lysosomal-like rather than NE-type

granules (Figure 6). Some of these cells extended

processes to adjacent carcinoma cells.

Immunoelectron Microscopy

CgA-immunoreactive prostate cancer cells, as seen

on light microscopy of semithin sections, were

detected in 1 of the 4 tumors analyzed by immuno-

electron microscopy. The immunoreactive malignant

cells were observed in the poorly differentiated

FIGURE 2 Relationship between NE differentiation and clinical

stage.

FIGURE 3 Relationship between NE differentiation and histo-

logical grade.

FIGURE 1 Immunohistochemical analysis of CgA staining in neoplastic glands (A) Well-differentiated tumors. NE cells are scattered in

the glands; immunostaining score: þ1. (B) Moderately differentiated tumors. NE cells are focal or clustered; immunostaining score: +2. (C)

Poorly differentiated tumors. Diffuse NE cells are seen in the glands; immunostaining score: þ3.

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glands, and were characterized by the presence of

pleomorphic CgA-positive granules, round or elon-

gated in shape and of various sizes (Figure 7). The

morphological features of these immunoreactive

granules in the poorly differentiated glands were

similar to those in the poorly differentiated NE malig-

nant cells examined by conventional electron

microscopy.

DISCUSSION

NE cells, histologically identified by immunostain-

ing for serotonin and chromogranin [4, 10] or by sil-

ver precipitation reactions [11], are present in small

cell carcinomas or carcinoid tumors [1]. Although

small cell carcinomas or carcinoid tumors of the

prostate are extremely rare, NE differentiation in

prostatic adenocarcinoma is more frequent [2, 3]. In

the current study, none of the tumors had the

histological appearance specific to small cell NE

carcinomas or carcinoid tumors observed upon

hematoxylin and eosin staining, and the histology

spectrum for the carcinomas with NE differentiation

ranged from well-differentiated microacinar, through

cribriform, to poorly differentiated, as shown by

immunohistochemical analysis.

Pruneri et al. [12] have suggested that NE differen-

tiation was not associated with clinical stage, but was

related to a high Gleason score, while Speights et al.

[13] reported that NE differentiation and the prolifer-

ation index in high-grade=high-stage disease were

increased compared to those in low-grade=low-stage

disease. In this study, immunohistochemical analysis

indicated that NE-differentiation status correlates

with both high stage and high grade of disease.

As we [15] and Abrahamsson [14] have reported,

there is an association between the clinical features of

NE differentiation in malignant glands and hormone-

refractory prostate cancer. These clinicopathological

features together with our immunohistochemical

FIGURE 4 Electron micrograph of NE neoplastic cells in well-differentiated tumors showing numerous neurosecretory granules (arrow).

371 Neuroendocrine-differentiated Carcinomas of the Prostate

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data suggest that NE differentiation in the malignant

prostatic glands is associated with aggressive beha-

vior and poor prognosis.

In conventional electron microscopy studies, NE

cells can be identified by the presence of classic

dense core granules in the cytoplasm [16, 17]. In this

study, malignant NE-differentiated cells were

identified in only 3 (33%) of the 9 specimens evalu-

ated by electron microscopy; 2 of these NE-positive

specimenswereobtainedfrompatientswithhormone-

refractory prostate cancer following androgen-

deprivation therapy. Weaver et al. studied the

characteristics of the granules in NE-differentiated

cells [17]. They found that the NE-differentiated

benign epithelial cells in the prostate contained elec-

tron-dense, lysosomal-like or exocrine-like granules

of variable size (460–690 nm) that filled the supra-

nuclear cytoplasm, while cells of prostatic carcino-

mas with Paneth cell-like change had NE-type

granules ranging from 240 to 480 nm. In contrast,

di Sant’ Agnese and de Mesy Jensen [16] pointed out

that cells from several NE-differentiated carcinomas

had an increased number of pleomorphic granules

when compared with benign prostatic NE cells. Heitz

andWegmann [18] described Paneth cells in an adeno-

carcinoma of stomach; these cells, histochemically

similar to NE-differentiated cells in prostatic carcino-

mas, had supranuclear homogeneous electron-dense

granules, an extensive Golgi complex, parallel arrays

of paranuclear rough endoplasmic reticulum, and

short microvilli. In the current study, NE-differen-

tiated cells in the well-differentiated malignant

glands possessed relatively homogeneous electron-

dense granules located in the supranuclear region,

some of which excreted into the lumen; however,

the other organelles were not developed. In the

poorly differentiated glands, NE-differentiated carci-

noma cells contained pleomorphic and lysosomal-

like granules of varying sizes, rather than NE-type

granules, and we demonstrated that the pleomorphic

FIGURE 5 Electron micrograph of NE neoplastic cells in moderately differentiated tumors showing relatively pleomorphic secretory

granules in clustered NE neoplastic cells.

D. Hirano et al. 372

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or lysosomal-like granules observed by conventional

electron microscopy stained for CgA in the immunoe-

lectron microscopy analysis.

To our knowledge, no immunoelectron micro-

scopy study of NE-differentiated carcinomas

of the prostate has been published, while there have

been several such reports for carcinomas of other

organs, such as colon [19] and breast [20], using post-

embedding immunoelectron microscopy with a col-

loidal gold-labeled antibody. The NE tumors arising

from these organs had a relatively higher proportion

of NE-differentiated neoplastic cells. This study sug-

gests that pre-embedding proedures are appropriate

for identification of NE-differentiated prostatic carci-

nomas by immunoelectron microscopy; thus, among

the cancer cells that could be evaluated by light

immunohistochemical microscopy, over 10% CgA-

stained malignant cells were found in only 8 of the

77 specimens (10.3% of the cases) as well as the

extremely sparseness of NE-differentiated neoplastic

cells in the conventional electron microscopic

observation.

With respect to the biological characteristics of

prostatic carcinomas with marked NE features,

Bonkhoff et al. [3] documented that CgA-positive

tumor cells lacked the proliferation-associated MIB-

1 and Ki67 antigens that identify cycling cells in G1,

S, and M phases of the cell cycle, and exocrine cells

with increased proliferative activity were detected

surrounding these NE tumor cells. Endocrine cells

in prostate cancer produce a variety of regulatory

peptides with growth-promoting activities in vitro,

including serotonin, bombesin, and parathyroid

hormone-related peptide [4, 5, 21], while NE neoplas-

tic cells lack androgen receptors [22]. In addition,

recent studies [23, 24] show that prostatic NE cells

express the new anti-apoptosis protein, survivin,

and that prostate cancer cells with NE features escape

programmed cell death. These biological features,

together with our immunohistochemical and electron

FIGURE 6 Electron micrograph of NE neoplastic cells in poorly differentiated tumors showing lysosomal-like rather than neurosecre-

tory, pleomorphic granules of various sizes.

373 Neuroendocrine-differentiated Carcinomas of the Prostate

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microscopy findings, suggest that NE neoplastic cells

act on the proliferation of surrounding cancer cells in

malignant tissues through the NE granules.

In conclusion, this study showed that the NE-

differentiation status in common prostate cancer

tissues was significantly increased in high-stage or

high-grade disease, and that poorly differentiated

NE malignant cells contained extremely pleomorphic

granules. In addition, we confirmed the presence of

CgA-immunoreactive deposits in the pleomorphic

granules by immunoelectron microscopy. These

results strongly suggest that NE-differentiated malig-

nant cells in prostate cancer tissues may induce

aggressive behavior in adjacent proliferating neo-

plastic cells via a paracrine mechanism.

REFERENCES

1. di Sant’ Agnese PA. Neuroendocrine differentiation in carcinoma ofthe prostate: Diagnostic, prognostic and therapeutic implications.Cancer. 1992;70:254–258.

2. di Sant’ Agnese PA, Cockett AT. Neuroendocrine differentiation inprostatic malignancy. Cancer. 1996;78:357–361.

3. Bonkhoff H, Wernert N, Dhom G, Remberger K. Relation of neuro-endocrine–paracrine cells to proliferation in normal, hyperplasticneoplastic human prostate. Prostate. 1991;19:91–98.

4. Abrahamsson PA, Wadstrom LB, Alumets J, Falkmer S, Grimelius L.Peptide hormone and serotonin-immunoreactive cells in carcinomaof the prostate. Pathol Res Pract. 1987;182:298–307.

5. Aprikian A, Han K, Guy L, Landry F, Begin LR, Chevalier S. Neuroen-docrine differentiation and bombesin=gastrin-releasing peptide fam-ily of neuropeptides in the progress of human prostate cancer.Prostate Suppl. 1998;82:738–743.

6. Haper ME, Glynne-jones E, Goddard L, Thurston VJ, Griffiths K. Vas-cular endothelial growth factor (VGEF) expression in prostatic tumorsand its relationship to neuroendocrine cells. Br J Cancer.1996;74:910–916.

7. di Sant Agnese PA, de Mesy Jensen K. Somatostatin and somatosta-tin-like immunoreactive endocrine–paracrine cells in the human pros-tate gland. Arch Pathol Lab Med. 1984;108:693–696.

8. Jewett HJ. The present status of radical prostatectomy for stage Aand B prostatic cancer. Urol Clin North Am. 1975;2:105–124.

9. Mostofi FK. Problems of grading carcinoma of prostate. Semin Oncol.1976;3:161–169.

10. Wilson BS, Lioyd RV. Detection of chromogranin in neuroendocrinecells with a monoclonal antibody. Am J Pathol. 1984;115:458–468.

11. Aguirre P, Scully RE, Wolfe HJ, Delellis RA. Endometrial carcinomawith argyrophil cells: A histochemical and immunohistochemicalanalysis. Hum Pathol. 1984;15:210–217.

FIGURE 7 Immunoelectron micrograph of NE neoplastic cells showing CgA-immunoreactive deposits in pleomorphic granules.

D. Hirano et al. 374

Ultr

astr

uct P

atho

l Dow

nloa

ded

from

info

rmah

ealth

care

.com

by

SUN

Y S

tate

Uni

vers

ity o

f N

ew Y

ork

at S

tony

Bro

ok o

n 10

/31/

14Fo

r pe

rson

al u

se o

nly.

12. Pruneri G, Galli S, Rossi RS, et al. Chromogranin A and B secretogra-nin II in prostatic adenocarcinomas: Neuroendocrine expression inpatients untreated and treated with androgen deprivation therapy.Prostate. 1998;34:113–120.

13. Speights VO, Cohen MK, Riggs MW, Coffield KS, Keegan G, Arber DA.Neuroendocrine stains and proliferative indices of prostatic adenocarci-nomas in transurethral resection samples. Br J Urol. 1997;80:281–286.

14. Abrahamsson PA. Neuroendocrine differentiation and hormonerefractory prostate cancer. Prostate Suppl. 1996;6:3–8.

15. Hirano D, Okada Y, Minei S, Takimoto Y, Nemoto N. Neuroendocrinedifferentiation in hormone refractory prostate cancer followingandrogen deprivation therapy. Eur Urol. 2004;45:586–592.

16. di Sant’ Agnese PA, de Mesy Jensen K. Neuroendocrine differen-tiation in prostatic carcinoma. Hum Pathol. 1987;18:849–856.

17. Weaver MG, Abdul-Karim FW, Strigley J, Bostwick DG, Ro JY, AyalaAG. Paneth cell-like change of the prostate gland: A histological,immunohistochemical, and electron microscopic study. Am J SurgPathol. 1992;16:62–68.

18. Heitz PU, Wegmann W. Identification of neoplastic paneth cells in anadenocarcinoma of the stomach using lysozyme as a marker, andelectron microscopy. Virchows Arch A. 1980;386:107–116.

19. Seretis E, Gavrill A, Agnantis N, Golematis V, Voloudakis-Baltatzis IE.Comparative study of serotonin and bombesin in adenocarcinomasand neuroendocrine tumors of the colon. Ultrastruct Pathol.2001;25:445–454.

20. Monaghan P, Roberts JDB. Immunocytochemical evidence for neu-roendocrine differentiation in human breast carcinomas. J Pathol.1985;147:281–289.

21. Iwamura M, Wu G, Abrahamsson PA, di Sant’ Agnese PA,Cockett ATK, Deftos LJ. Parathyroid hormone-related protein isexpressed by prostatic neuroendocrine cells. Urology.1994;43:667–674.

22. Krijnen JLM, Janssen PJA, Ruizevel de Winter JA, van Krimpen H,Shroder FH, van der Kwast TH. Do neuroendocrine cells in humanprostate cancer express androgen receptor? Histochemistry.1993;100:393–398.

23. Xing N, Qian J, Bostwick D, Bergstralh E, Young CYF. Neuroendo-crine cells in human prostate over-express the antiapoptosis proteinsurviving. Prostate. 2001;48:7–15.

24. Fixemer T, Remberger K, Bonkhoff H. Apoptosis resistance of neu-roendocrine phenotype in prostatic adenocarcinoma. Prostate.2002;53:118–123.

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