Cytogenetic findings in two new cases of hepatoblastoma

Upregulated genes at 2q24 gains as candidate oncogenes in hepatoblastomas

AIM

Cytogenetic data of hepatoblastomas, a rare embryonal tumor of the liver, mostly consist of descriptions of whole-chromosome aneuploidies and large chromosome alterations. High-resolution cytogenetics may provide clues to hepatoblastoma tumorigenesis and indicate markers with clinical significance.

PATIENTS & METHODS

We used array-CGH (180K) to screen for genomic imbalances in nine hepatoblastomas. Additionally, we investigated the expression pattern of selected genes exhibiting copy number changes.

RESULTS

Analysis showed mainly whole-chromosome or chromosome-arm aneuploidies, but some focal aberrations were also mapped. Expression analysis of 48 genes mapped at one 10 Mb amplification at 2q24 revealed upregulation of DAPL1, ERMN, GALNT5, SCN1A and SCN3A in the set of tumors compared with differentiated livers.

CONCLUSION

These genes appear as candidates for hepatoblastoma tumorigenesis.

Copy-number variations in hepatoblastoma associate with unique clinical features

PURPOSE

Hepatoblastoma is a rare childhood liver malignancy with limited relevant cytogenetic data. This study aimed to discover common genomic copy-number variations (CNVs) in subjects with hepatobalstoma and its relevance to the clinical course.

METHODS

Gene copy-number was systemically rated by high-resolution comparative genomic hybridization (CGH) DNA oligonucleotide microarray. The study group consisted of 12 children (7 males and 5 females) with hepatoblastoma and another 20 healthy individuals (10 males and 10 females) as controls. The influence of recurrent CNVs on clinical outcomes was analyzed.

RESULTS

Four highly recurrent CNVs were identified in these 12 hepatoblastoma children after comparison with controls, including a gain on 1p13.3 (n = 3, 25%) and losses on 5p15.33 (n = 4, 33.3%), 16q12.2 (n = 4, 33.3%), and 19q13.42 (n = 3, 25%). The most prevalent sites of genomic deletion were 5p15.33 and 16q12.2. Zinc finger, DHHC-type containing 11 (ZDHHC11) and DHHC-type containing 11B (ZDHHC11B) were mapped to 5p15.33, which was associated with a lower rate of survival with native liver (p = 0.03). The carboxylesterase 4-like (CES4) gene that mapped to 16q12.2 was associated with smaller tumor size at presentation.

CONCLUSIONS

Deletions of 5p15.33 (33.3%) and 16q12.2 (33.3%) are the most frequent hepatoblastoma-related events in our patient group with 5p15.33 microdeletion as a potential biomarker for the fate of survival with native liver.

Cytogenetic and array comparative genomic hybridization analysis of a series of hepatoblastomas

Hepatoblastoma is the most common primary hepatic tumor in children, and only a limited number of detailed karyotypic analyses have been reported to date. In the present study, cytogenetic abnormalities were identified in nine cases of hepatoblastoma from a single institution. Among characteristic chromosomal changes detected were simple numerical aberrations, structural alterations of chromosomes 1, 2, and 8, and the recurrent unbalanced rearrangements der(4)t(1;4)(q25.2;q35.1) and der(6)t(1;6)(q21;q26). Array comparative genomic hybridization was applied in four of the cases. The combined cytogenetic, molecular cytogenetic, and histopathologic analyses are presented here, together with clinical data. The results substantially confirm previous findings of aberrations involving chromosomal loci on 1q, 2 or 2q, 4q, 6q, 8 or 8q, and 20 as significant in the development and clinical course of this disease.

Pleuropulmonary blastoma: cytogenetic and spectral karyotype analysis

Pleuropulmonary blastoma (PPB) is a rare neoplasm of the pleuropulmonary mesenchyme. The molecular mechanisms underlying the genesis of this tumor are of particular interest as a large number of affected patients as well as their relatives have concurrent disease including additional dysplasia or neoplasia. To date, detailed karyotypes have been published on a limited number of cases. We report clinical, pathologic, and cytogenetic data in 2 cases of PPB including spectral karyotyping in 1 of them. Additionally, we conducted a review of the literature and compiled 15 published karyotypes of this tumor. Gain of chromosome 8 material was a highly prevalent finding in PPB, most times occurring as trisomy, but tetrasomy of the long arm was also frequent. Other occurring abnormalities, in order of observed frequency, included loss of 17p, loss of chromosome 10 or 10q, rearrangement of 11p, loss of chromosome X or Xp, gain of chromosomes/arms 1q, 2, and 7q, and loss of 6q and 18p. Loss of 10q has not been previously emphasized in PPB. The significance of these chromosome findings is discussed in relation to tumorigenesis.

Cytogenetic evaluation of a large series of hepatoblastomas: Numerical abnormalities with recurring aberrations involving 1q12-q21

Hepatoblastoma is a malignant embryonal liver tumor that occurs almost exclusively in infants and very young children. Previous cytogenetic studies of hepatoblastoma have investigated small series or individual cases. This report is on the cytogenetics of a large series of 111 hepatoblastoma specimens, with cytogenetic results consecutively karyotyped over a 12-year period. Abnormal karyotypes were observed in 55 cases (approximately 50% of the total). Numerical aberrations were observed in 41 cases (36% of the total), particularly trisomies of chromosomes 2, 8, and 20. Chromosome losses were less common than chromosome gains. Structural abnormalities were observed in 43 cases (39% of the total). Unbalanced translocations resulting in trisomy 1q and involving breakpoints at 1q12-21 were the most common structural abnormality, observed in 20 tumors (18% of total cases); the corresponding translocated chromosome was highly varied. The previously reported t(1;4) was observed in seven cases. Most tumors with translocations involving 1q12-21 also displayed numerical chromosome aberrations, the most common of which were chromosomal trisomies, whereas tumors with other structural rearrangements had fewer numerical abnormalities.

Cytogenetic abnormalities in hepatoblastoma: report of two new cases and review of the literature suggesting imbalance of chromosomal regions on chromosomes 1, 4, and 12

Two cases of hepatoblastoma with unique karyotypic changes are described. One case was that of a 2-year-old boy with an unbalanced chromosomal translocation involving 4q35 as the sole chromosomal abnormality. The clonal karyotype of this tumor was 46,XY,add(4)(q35)[3]/46,XY[9]. In the other case, that of a 2-year-old boy, karyotypic analyses revealed the clonal karyotype as 57,XY,+del(1)(p22),+2,+5,+6,+7,+8,+del(12)(p12),+18,+19,+20,+22[4]/46,XY[12]. Review of these two cases, together with previous reports, underscored the significance of numerical and/or structural chromosomal abnormalities of 1q, 4q, 2, 8, and 20 in the development of hepatoblastoma. The present results show that imbalance of the terminal region of 4q could be the sole chromosomal abnormality in a hepatoblastoma. We also found that imbalance of chromosomal regions on chromosomes 1 and 12 may contribute to the development of hepatoblastoma.

Where do we stand with hepatoblastoma? A review

Hepatoblastoma (HB) is the most common pediatric liver malignancy, comprising approximately 1% of all pediatric cancers. The disparate clinical staging systems and histologic classifications that were developed during the last decades, nevertheless, reflect the remaining difficulties and uncertainties in characterizing HB. Furthermore, the combination of surgery and (neo)adjuvant chemotherapy has improved patient outcomes dramatically. A poor prognosis is associated with large tumor size, multifocality, extrahepatic disease, and metastatic spread. The exact etiology of HB remains unknown, but the cytogenetic alterations, phenotypic features, and biologic aspects that accompany this neoplasm yield more and more insight into its pathogenesis. New cell-biologic and molecular-biologic insights may lead to the development of new treatment modalities, especially for patients with a bad prognosis. This review summarizes the different aspects of this intriguing tumor and discusses the current status of research and treatment for patients with HB.

Two novel in vitro human hepatoblastoma models, HepU1 and HepU2, are highly characteristic of fetal-embryonal differentiation in hepatoblastoma

Using comparative genomic hybridization (CGH), we present a genome-wide screening of a mixed mesenchymal-epithelial hepatoblastoma, its recurrence and 2 novel hepatoblastoma cell lines raised from the ascites, 18 (HepU1) and 23 (HepU2) months after diagnosis of a hepatoblastoma in a 35-month-old boy. Both cell lines were also characterized by GTG-banding, multicolor-fluorescence in situ hybridization (M-FISH) and multicolor banding (M-Band). On the basis of CGH, we compared the cytogenetics of histologically different tumor areas of the parental tumor and its recurrence with the hepatoblastoma cell lines. We found different CGH profiles in the parental tumor rev ish enh(1q31-q32,8p,12,17,20,X), dim(4q34-q35,18q23)[cp] and its recurrence rev ish enh(8q24,17,Xq26-q28), dim(7q11.2-q21,13q34)[cp]. Although both epithelial cell lines were obtained at different times and the clonal ancestor of HepU2 had been exposed to a higher cumulative dose of chemotherapy, HepU1 and HepU2 have an identical karyotype: 48-56,XY,+Y,dup(2)(q32-q34),t(3;4)(q21;q34),+8,+12,+13, +17,+t(18;19)(q21;q?),+20[cp] and identical CGH profiles: rev ish enh(2q24-q33,8,12,13q,17,20), dim(4q34-q35,18q22-q23). In common with previously described hepatoblastoma cell lines, HepU1 and HepU2 demonstrate a gain of chromosome 20. The in situ aberrations most closely resembling that of HepU1 and HepU2 were found in areas of fetal-embryonal differentiation of the primary tumor. Interestingly, both cell lines mimic this histology in their three-dimensional growth pattern in vitro. HepU1 and HepU2 are thus cytogenetically and phenotypically highly characteristic of fetal-embryonal hepatoblastoma.