Correspondence

Beckwith-Wiedemann Syndrome,Pancreatoblastoma, and the Wnt SignalingPathway

To the Editor-in-Chief:

In a recent issue of The American Journal of Pathology,Abraham et al1 reported frequent alterations in the wntsignaling pathway and chromosome 11p LOH (loss ofheterozygosity) in sporadic and familial adenomatouspolyposis-associated pancreatoblastomas. The molecu-lar association between pancreatoblastoma and otherembryonal tumors such as hepatoblastoma and Wilm’stumor has been previously suggested by the presenta-tion of Beckwith-Wiedemann in children with these tu-mors.2–4 However, the study of Abraham et al1 did notdescribe any case of pancreatoblastoma presenting withBeckwith-Wiedemann syndrome.

Here we report a case of pancreatoblastoma present-ing in a four-year-old male with incomplete Beckwith-Wiedemann syndrome, consisting of hemihypertrophy ofthe right foot and leg (case 1). On examination the tumorwas shown to have LOH of 11p, which included the11p15 BWS gene region and IGF2.5 The genetic mech-anism underlying this patient’s 11p LOH must be consti-tutional, although only present in the cells of the limbshowing hemihypertrophy. In contrast, all cases of spo-radic pancreatoblastoma presented by Abraham et al1

would have a tumor-specific 11p 15 LOH which hasoccurred as a somatic event. A second case of pancre-atoblastoma presenting in a three-year-old femaleshowed partial LOH of 11p.

Immunohistochemistry showed accumulation of a-catenin in the cytoplasm and nucleus of both pancreato-blastomas. Case 1 was found to have a missense muta-tion in exon 3 of the �-catenin gene (CTNNB1) whichcaused an amino acid substitution of serine 37 (TCT) to aphenylalanine (TTT). Serine 37 is one of the four threo-nine/serine phosphorylation sites essential for GSK-3�-dependent phosphorylation and has been characterizedas a ubiquitination-targeting motif. This S37F mutationwas found in case P4 of Abraham et al.1 Case P4 alsoshowed 11p LOH, however the parental origin of the lostallele could not be determined. In case 1 described here,LOH of 11p 15.5 was maternal in origin.5 As stated byAbraham et al1 maternal allelic loss of 11p 15.5 would beexpected based on data from Wilm’s tumor and hepato-blastoma. Sequence analysis of exon 3 in the secondcase of pancreatoblastoma did not reveal a mutation.Large deletions of the �-catenin NH2-terminal regulatory

domain have been previously described in melanomacell lines and colorectal cancers.6 Therefore, case 2 wasscreened for larger deletions using primers that scannedexon 3 and the adjacent introns of CTNNB1. However, alarge deletion was not found. In this case nuclear accu-mulation of �-catenin without mutation of CTNNB1 couldbe caused by genetic alteration of down-regulators ornegative repressors of the CTNNB1 gene such as APC,PP2A, Tef1, or AXIN1. Genes in the Wnt signaling path-way have been found to be mutated in many types ofcancer. As case 2 was of Asian descent, mutation of theAPC gene may be likely since the Asian population hasbeen shown to have a high incidence of APC mutationsleading to cellular �-catenin accumulation in hepatoblas-toma.7 These cases provide further evidence that alter-ations in the wnt signaling pathway play a significant rolein the progression of pancreatoblastoma tumorigenesis.

Natalie J. KerrRyuji Fukazawa

Anthony E. ReeveUniversity of OtagoDunedin, New Zealand

Michael J. SullivanChristchurch School of MedicineChristchurch, New Zealand

References

1. Abraham SC, Wu TT, Klimstra DS, Finn LS, Lee JH, Yeo CJ, CameronJL, Hruban RH: Distinctive genetic alterations in sporadic and familialadenomatous polyposis-associated pancreatoblastomas: frequentalterations in the APC/�-catenin pathway and chromosome 11p. Am JPathol 2001, 159:1619–1627

2. Drut R, Jones MC: Congenital pancreatoblastoma in Beckwith-Wiede-mann syndrome: an emerging association. Pediatr Pathol 1988,8:331–339

3. Koh THHG, Cooper JE, Newman CL, Walker TM, Kiely EM, BlumHoffmann E: Pancreatoblastoma in a neonate with Wiedemann-Beck-with syndrome. Eur J Pediatr 1986, 145:435–438

4. Potts SR, Brown S, O’Hara MD: Pancreatoblastoma in a neonateassociated with Beckwith-Wiedemann syndrome. Z Kinderchir 1986,41:56–57

5. Kerr NJ, Chun YH, Yun K, Heathcott RW, Reeve AE, Sullivan MJ:Pancreatoblastoma is associated with chromosome 11p loss of het-erozygosity and IGF2 overexpression. Med Paed Oncol 2001, inpress

6. Rubbinfeld B, Robbins P, El-Gamil M, Albert I, Porfiri E, Polakis P:Stabilization of beta-catenin by genetic defects in melanoma celllines. Science 1997, 275:1790–1792

7. Oda H, Imai Y, Nakatsura Y, Hata J, Ishikawa T: Somatic mutations ofthe APC gene in sporadic hepatoblastoma. Cancer Res 1996, 56:3320–3323

American Journal of Pathology, Vol. 160, No. 4, April 2002

Copyright © American Society for Investigative Pathology

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Authors’ Reply

We are very pleased to hear of the molecular abnormal-ities in two new pancreatoblastomas of Kerr et al.2 In ourrecent study of nine pancreatoblastomas, allelic loss onchromosome 11p15.5 was present in 6 of 7 informativecases (86%), and mutations in the APC/�-catenin path-way in 6 of 9 cases (67%).1 These findings underscorethe clinical association between pancreatoblastoma for-mation and Beckwith-Wiedemann syndrome, as well as apotential association of pancreatoblastoma with familialadenomatous polyposis (FAP).

In the two additional pancreatoblastomas reported byKerr et al,2 11p15.5 allelic loss was found in both neo-plasms, similar to the very high rate of 11p loss found inour series.1,2 In this regard, case 1 of Kerr et al2 isparticularly exciting because this pancreatoblastomashowed selective loss of the maternal allele, somethingthat we could not document in our pancreatoblastomasfor which parental tissue was not available.1,2 This selec-tive loss of the maternal 11p15.5 allele has been previ-ously described in hepatoblastomas3 (neoplasms withclinical and genetic similarity to pancreatoblastomas),but not in pancreatoblastomas, and this strengthensthe molecular link of pancreatoblastoma to Beckwith-Wiedemann syndrome.

The finding of Kerr et al2 of an activating �-cateningene mutation in 1 of 2 pancreatoblastomas is alsosimilar to our rate of �-catenin mutations in 5 of 8sporadic (non-FAP associated) pancreatoblastomas,1

and underscores the importance of alterations in theAPC/�-catenin pathway in pancreatoblastoma devel-opment. It is certainly interesting to speculate whatalternative molecular alterations in this pathway mightbe present in those cases that lack demonstrable�-catenin mutations. As noted by Kerr et al,2 somepossibilities would include inactivating APC or AXIN1mutations. Our series included one patient with FAPwhose pancreatoblastoma showed biallelic APC inac-tivation (a germ-line truncating mutation coupled withsomatic 5q allelic loss) rather than �-catenin mutation;we could not detect APC mutations in either of twosporadic pancreatoblastomas that were negative for�-catenin mutations. However, it is certainly possiblethat the pancreatoblastoma in the Asian patient de-scribed by Kerr et al2 might show APC inactivation,since some hepatoblastomas in Asian, but not West-ern, patients have been shown to contain APC muta-tions.4

The 11 pancreatoblastomas which to date have beenevaluated for molecular alterations in 11p and the APC/�-catenin pathway bear out two important points. First,the occasional occurrence of these tumors in patientswith germ-line DNA abnormalities (in this case, Beckwith-Wiedemann syndrome and FAP) provides a clue to thegenetic alterations in these tumors themselves. Second,the sporadic variants of these tumors will frequently har-bor alterations in the same genes or in related genes ofthe same molecular pathway.

Susan C. AbrahamRalph H. Hruban

Johns Hopkins University School of MedicineBaltimore, Maryland

References

1. Abraham SC, Wu TT, Klimstra DS, Finn LS, Lee JH, Yeo CJ, CameronJL, Hruban RH: Distinctive genetic alterations in sporadic and familialadenomatous polyposis-associated pancreatoblastomas: frequentalterations in the APC/�-catenin pathway and chromosome 11p. Am JPathol 2001, 159:1619–1627

2. Kerr NJ, Chun YH, Yun K, Heathcott RW, Reeve AE, Sullivan MJ:Pancreatoblastoma is associated with chromosome 11p loss of het-erozygosity and IGF2 overexpression. Med Paed Oncol 2001, inpress

3. Albrecht S, von Schweinitz D, Waha A, Kraus JA, von Deimling A,Pietsch T: Loss of maternal alleles on chromosome arm 11p in hepa-toblastoma. Cancer Res 1994, 54:5041–5044

4. Oda H, Imai Y, Nakatsura Y, Hata J, Ishikawa T: Somatic mutations ofthe APC gene in sporadic hepatoblastoma. Cancer Res 1996, 56:3320–3323

KAI1 Metastasis Suppressor Protein in CervicalCancer

To the Editor-in-Chief:

We have read with interest the article of Liu et al1 ondown-regulation of KAI1-metastasis suppressor proteinin cervical cancer.1 This study confirms our results pub-lished previously.2 Unfortunately Liu et al1 missed one ofour papers on KAI-1 expression in cervical carcinoma,wherein some of the problems discussed in their paperhave already been addressed. Liu et al1 suggest thatdown-regulation of KAI1 might occur early in cervicalcarcinogenesis, but they did not include any precancer-ous lesions of the cervix in their study. In contrast, basedon immunostaining of various stages of cervical dyspla-sia, we demonstrated that down-regulation of KAI in factoccurs at a very early stage of cervical carcinogenesis,while in 10 cases of cervical intraepithelial neoplasia(CIN) grade I, strong KAI1 expression was found in allcases, no difference in KAI1 expression in CIN II (n � 10)or CIN III (n � 10) and invasive carcinomas (n � 75) wasfound (P �0.05, Kruskal-Wallis test). Liu et al1 also hy-pothesize that KAI1 may not have a prognostic influencein cervical cancer, but were not able to perform survivalanalysis due to the short follow-up time of patients. In ourcollective of primary irradiated cervical cancers we havedemonstrated that KAI1 down-regulation was indeed notassociated with prognosis (P �0.05, log-rank test).

In our view, a technical problem of the real time-re-verse transcriptase-polymerase chain reaction-basedstudy of Liu et al1 is the fact that KAI1 is also stronglyexpressed in lymphocytes and macrophages,3 as statedby Liu and colleagues themselves.1 In cervical cancer,inflammatory stroma reaction is a common event, and iseven very prominent in many cases.4 To us, mRNA- orprotein-based methods for detection of KAI1 expressionwithout reliable separation of tumor cells from the sur-

1542 CorrespondenceAJP April 2002, Vol. 160, No. 4