Genetic changes in hepatoblastoma

A functionalized magnetic nanoparticle regulated CRISPR-Cas12a sensor for the ultrasensitive detection of alpha-fetoprotein

Alpha-fetoprotein (AFP) is an important clinical tumor marker of hepatoblastoma, and the concentration of AFP in serum is closely related to the staging of hepatoblastoma. We report a magnetic bead separation platform based on a switching aptamer triggered hybridization chain reaction (SAT-HCR) and the CRISPR-Cas12a sensor for the in vitro detection of AFP. AFP aptamer, as an easily regulated nucleic acid strand, is responsible for binding to AFP into nucleic acid detection, while HCR-CRISPR-Cas12a, regulated by functionalized magnetic nanoparticles, is responsible for highly specific nucleic acid signal amplification. Under the optimal conditions, the fluorescence intensity was proportional to the concentration of AFP in the range of 0.5-10⁴ ng mL^-1 and the limit of detection was 0.170 ng mL^-1. In addition, we have successfully applied this biosensor to detect AFP in clinical samples from patients with hepatoblastoma, with greater sensitivity relative to ELISA. Our proposed method showed great potential application in clinical diagnosis and pharmaceutical-related fields with the properties of high sensitivity, low cost and high selectivity.

The Genetic Changes of Hepatoblastoma

Hepatoblastoma is the most common malignant liver cancer in childhood. The etiology of hepatoblastoma remains obscure. Hepatoblastoma is closely related to genetic syndromes, hinting that hepatoblastoma is a genetic predisposition disease. However, no precise exposures or genetic events are reported to hepatoblastoma occurrence. During the past decade, significant advances have been made in the understanding of etiology leading to hepatoblastoma, and several important genetic events that appear to be important for the development and progression of this tumor have been identified. Advances in our understanding of the genetic changes that underlie hepatoblastoma may translate into better patient outcomes. Single nucleotide polymorphisms (SNPs) have been generally applied in the research of etiology's exploration, disease treatment, and prognosis assessment. Here, we reviewed and discussed the molecular epidemiology, especially SNPs progresses in hepatoblastoma, to provide references for future studies and promote the study of hepatoblastoma's etiology.

Circulating D-dimer level correlates with disease characteristics in hepatoblastoma patients

OBJECTIVES

Hepatoblastoma (HB) is the most common pediatric liver malignancy, typically affecting children within the first 4 years of life. However, only a few validated blood biomarkers are used in clinical evaluation. The current study explored the clinical application and significance of D-dimer levels in patients with HB.

METHOD

Forty-four patients with HB were included in this retrospective study. D-dimer and plasma fibrinogen levels were examined, and their correlation with other clinical features was analyzed. D-dimer and plasma fibrinogen levels were examined between HB and other benign hepatic tumors.

RESULTS

D-dimer levels were significantly associated with high-risk HB features, such as advanced stage and high α-fetoprotein (AFP) levels. Higher D-dimer levels were observed in stage 4 patients compared with stage 1/2/3 patients (P = .028). Higher D-dimer levels were also observed in patients with higher AFP levels before chemotherapy compared with patients with lower AFP levels after chemotherapy (P< 0.001). In addition, higher D-dimer levels were observed in HB compared with other benign hepatic tumors such as hepatic hemangioma and hepatocellular adenoma (P = .012). No significant difference in D-dimer levels was found between sex (P = .503) and age (≥12 vs <12 months, P = .424). There was no significant difference in plasma fibrinogen levels between sex or age and high-risk HB features, such as advanced stage and high AFP levels.

CONCLUSIONS

Elevated D-dimer levels could be a useful determinant biomarker for high-risk features in patients with HB. This finding also supports the clinical application of D-dimer in HB.

Abdominal transplantation for unresectable tumors in children: the zooming out principle

PURPOSE

To present our experience in abdominal transplantations to manage unresectable abdominal neoplasms in children and to describe the role of extensive surgeries in such cases.

METHODS

This is a retrospective study of 22 abdominal transplantations in 21 patients for abdominal tumors over 16 years. Transplantation techniques included liver transplant (LT), multivisceral transplant (MVTx), and intestinal autotransplant (IA). Follow-up intervals ranged from 0.3 to 168 months (median 20 months).

RESULTS

LT alone was performed in 15 patients for primary malignant (11) and benign (4) liver tumors. Pathological classification included HB hepatoblastoma (6), HCC hepatocellular cancer (3), hepatic epithelioid hemangioendothelioma HEH (1), angiosarcoma (1), benign vascular tumors (3), and adenoma (1). IA was performed in four patients for lesions involving the root of the mesentery; tumors of the head of pancreas (3) and mesenteric hemangioma (1). MVTx was performed in 2 patients for malignancies; pancreaticoblastoma (1), recurrent hepatoblastoma (1), and in one patient as a rescue procedure after IA failure. Four of the eleven patients who underwent LT for malignant liver tumor had metastatic disease at presentation. Six of them died of recurrent neoplasm (3), transplant-related complications (2), and underlying disease (1). All LT patients who had benign tumors are alive with functioning grafts. All IA patients survived and are on an oral diet, with one patient requiring TPN supplementation. One of the three patients who underwent MVTx died of metastatic disease.

CONCLUSIONS

Allo/auto transplantation for abdominal tumors is a valuable modality when conventional treatments fail or are not feasible.

Detection of Serum Protein Biomarkers for the Diagnosis and Staging of Hepatoblastoma

The present study aimed to identify serum biomarkers for the detection of hepatoblastoma (HB). Serum samples were collected from 71 HB patients (stage I, n = 19; stage II, n = 19, stage III, n = 19; and stage IV, n = 14) and 23 age- and sex-matched healthy children. Differential expression of serum protein markers were screened using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS), and the target proteins were isolated and purified using HPLC and identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), SEQUEST, and bioinformatics analysis. Differential protein expression was confirmed by enzyme-linked immunosorbent analysis (ELISA). SELDI-TOF-MS screening identified a differentially expressed protein with an m/z of 9348 Da, which was subsequently identified as Apo A–I; its expression was significantly lower in the HB group as compared to the normal control group (1546.67 ± 757.81 vs. 3359.21 ± 999.36, respectively; p < 0.01). Although the expression level decreased with increasing disease stage, pair-wise comparison revealed significant differences in Apo A–I expression between the normal group and the HB subgroups (p < 0.01). ELISA verified the reduced expression of Apo A–I in the HB group. Taken together, these results suggest that Apo A–I may represent a serum protein biomarker of HB. Further studies will assess the value of using Apo A–I expression for HB diagnosis and staging.

Progress in the surgical treatment of malignant liver tumors in children

During the last decade, important progress has been made in the surgical treatment of malignant liver tumors in children. For hepatoblastoma, there is a general consensus for combining surgical resection with neoadjuvant (and adjuvant) chemotherapy. Long-term disease-free survival of around 85-90% can be achieved for resectable HB involving no more than three sections of the liver (PRETEXT I-III). For unresectable HB without extrahepatic invasion (PRETEXT IV with involvement of all four sections and some cases of PRETEXT III with invasion of, or close contact with major venous structures), similar results can be obtained with total hepatectomy and liver transplantation. For hepatocellular carcinoma, most often without underlying liver disease in children of the western world, results of resection with partial hepatectomy remain dismal, due to a high rate of recurrence. In contrast, remarkable survival rates have been obtained during the last decade with liver transplantation. There is no argument, either biological or based on evidence, that the selection of pediatric candidates for transplantation should be based on the same criteria as in adult patients (the Milan criteria). Optimization of results require to concentrate children with a malignant liver tumors in specialized, multidisciplinary pediatric centers with expertise in chemotherapy and in both major liver resections and transplantation. Enrolling these children in prospective trials should be encouraged, as well as prospective registration of transplanted patients in PLUTO (Pediatric Liver Unresectable Tumor Observatory-http://Pluto.cineca.org) in order to clarify issues unresolved by retrospective studies.

RBMY, a male germ cell-specific RNA-binding protein, activated in human liver cancers and transforms rodent fibroblasts

The RNA-binding motif (RRM) gene on Y chromosome (RBMY), encoding a male germ cell-specific RNA-binding protein associated with spermatogenesis, was found inserted by hepatitis B virus (HBV) DNA in one childhood hepatocellular carcinoma (HCC). This study is aimed to explore the oncogenic potential of the RBMY protein. The RBMY transcripts, expressed exclusively in the testis of normal people, were detected by reverse transcription-polymerase chain reaction in 36% of HCCs from 90 males and in 67% of hepatoblastoma from six boys. The nontumor liver counter parts, cirrhotic liver tissues from children with biliary atresia, and other types of cancers, such as bile duct, colon, stomach, lung, prostate, and kidney, were all negative for RBMY expression. One to four types of RBMY transcripts, including wild type and variants with N-terminal RRM deletion, C-terminal SRGY (serine-arginine-glycine-tyrosine) boxes deletion, or deletion of both domains, were found in the testis and liver cancer tissues. The wild-type RBMY protein was expressed in the nucleus and demonstrated its tumorigenicity by transformation of mouse fibroblast NIH3T3 cells and in vivo tumor formation. The RBMY variant protein with deletion of C-terminal exons 9-12 was trapped in the cytoplasm and showed decreased tumorigenicity. Our results suggest that RBMY is a new candidate oncogene specific for male liver cancer.

Comparative genomic hybridization analysis of hepatoblastoma reveals high frequency of X-chromosome gains and similarities between epithelial and stromal components

Hepatoblastoma (HB) is the most common liver tumor in childhood and differs in its environmental risk factors and genetic background from hepatocellular carcinoma. HB is associated with inherited conditions such as familial adenomatous polyposis and Beckwith-Wiedemann syndrome, suggesting the importance of genetic abnormalities in the pathogenesis and progression of this disease. It has a very polymorphous morphology. A diverse range of cytogenetic alterations has been reported to date, the most frequent being trisomy 2 and trisomy 20. Thirty-five HB specimens from 31 patients (22 purely epithelial, 4 purely mesenchymal, 9 mixed) were examined by comparative genomic hybridization (CGH), a technique that enables us to screen the entire tumor genome for genetic losses and gains. Our aims were as follows: (1) to characterize chromosome abnormalities that appear in this tumor and (2) to identify possible differences between different histologic subtypes of HB. We found significant gains of genetic material, with very little difference in the number and type of alterations between the different histologic components of HB. The most frequent alterations were gains of Xp (15 cases, 43%) and Xq (21 cases, 60%). This finding was also confirmed by fluorescent in situ hybridization performed on nuclei extracted from 6 specimens. Other common alterations were 1p-, 2q+, 2q-, 4q-, and 4q+. We found no difference between different histologic subtypes, a finding that may be in agreement with the hypothesis of a common clonal origin for the different components. An hitherto-unreported high frequency of X chromosome gains may support the assumption that X-linked genes are involved in the development of this neoplasm.

Hypermethylation of the p16 gene and lack of p16 expression in hepatoblastoma

Hepatoblastoma is the most frequent pediatric liver tumor that develops mostly in young children. Abnormal regulation of cell cycle regulatory genes including p16 has been described, displaying no p16 mRNA and p16 protein in hepatoblastomas. The inactivation of p16, leading to the disruption of cell cycle control is involved in many types of human malignancies. However, the mechanism of the p16 inactivation in hepatoblastomas has not yet been elucidated. In this present study, we examined the methylation status of the p16 gene promoter by using methylation-specific PCR in 24 cases of hepatoblastomas and in 20 cases of corresponding non-neoplastic liver tissue. Aberrant methylation of 5' CpG islands of p16 was present in 12 of 24 (50.0%) cases of hepatoblastoma. Clinicopathologic parameters were not associated with the methylation status of p16. To correlate the methylation status of p16 with the expression of p16, immunohistochemical staining was done in tumors and non-neoplastic liver tissue. All non-neoplastic liver tissues displayed moderate, but heterogeneous immunoreactivity for p16. Eight of 12 (66.6%) methylation-positive hepatoblastomas showed a complete lack of immunoreactivity for p16. The other 4 methylation-positive hepatoblastomas had heterogeneous immunoreactivity. Nine of 12 (75.0%) unmethylated cases of hepatoblastoma displayed diffuse immunoreactivity, whereas 3 cases of unmethylated hepatoblastoma were not immunostained for p16. Our data indicate that the hypermethylation of p16 is a major mechanism of the transcriptional repression of p16 in hepatoblastomas, and we suggest that the inactivation of p16, leading to the lack of p16, may play an important role in the tumorigenesis of hepatoblastomas.

Cytogenetic findings in two new cases of hepatoblastoma

We describe two cases of hepatoblastoma occurring in an 18-month-old boy and a 3-month-old girl. Cytogenetic analysis of the primary tumors revealed gain of 2q and 20 in both cases. In case 1, t(7;8;11) was seen as a secondary abnormality. Other chromosomal aberrations seen in case 2 were unbalanced t(1;1) and t(2;11), resulting in partial gains of 1q and 2q. These results support previous reports that gains of 2q and 20 and rearrangement of chromosome 1 are strongly associated with hepatoblastoma and may be essential for establishing this neoplasm. The 11q and 7q abnormalities may represent a pathway of genetic evolution associated with hepatoblastoma progression.

Karyotypic analyses of hepatoblastoma. Report of two cases and review of the literature suggesting chromosomal loci responsible for the pathogenesis of this disease

Two cases of fetal hepatoblastoma with unique karyotypic changes are described. One was a 17-month-old boy with multiple unbalanced chromosomal translocations, resulting in four types of derivative chromosomes involving chromosomal loci at 1q21, 1q32, 2q23, 6q27, 7p22, and 21p12, partial tetrasomy of 1q, partial trisomy of 2q, and partial monosomy of 21p. The clonal karyotype of this tumor was 46,XY,der(2)t(1;2)(q32;q37), der(6)t(1;6)(q12;q27), der(7)t(2;7)(q23;p22), der(21)t(2;21) (q23;p12). In the other case, a 4-year-old girl, karyotypic analyses revealed trisomy 2 and 8, and the clonal karyotype of this case was 48,XX,+2,+8. Review of these cases together with previous reports suggested the significance of chromosomal changes including numerical abnormalities of 1q, 2(or 2q), 20, and 8 (or 8q), and breakage of 1q and 2q in the development of hepatoblastoma. The results presented herein underscore the significance of numerical abnormalities of chromosomal regions 1q and 2q and of chromosome 8 in the development of hepatoblastoma, in addition to abnormalities of 6q27, 7p22, and 21p12-13 as other chromosomal loci that may be responsible for the pathogenesis of this embryonal type of tumor.

Overexpression of cyclin D1 and cdk4 in tumorigenesis of sporadic hepatoblastomas

Abnormality of the cyclin D1/cdk4/p16INK4a/pRb pathway during tumorigenesis has recently been reported. Hepatoblastoma is a rare malignant liver tumor of childhood, but underlying abnormalities of cell-cycle regulating protein remain to be elucidated. The expression of cyclin D1, cdk4, p16 and retinoblastoma gene product (pRb) was studied by immunohistochemistry in 17 paraffin-embedded tissues consisting of both tumor and corresponding non-neoplastic tissues. Tumor tissues showed overexpression of cyclin D1 (13/17, 76%) and cdk4 (15/17, 88%). Eleven cases showed co-overexpression of both cyclin D1 and cdk4. No abnormal p16 or pRb expression was noted. In the group with a high score (+4) for cyclin D1 expression, a positive correlation with tumor recurrence was noted (P = 0.043). These data suggest that overexpressed cyclin D1 and cdk4 protein might play an important role in the tumorigenesis of hepatoblastoma and that in the group with high cyclin D1 expression, tumor recurrence may be more frequent.

Cytogenetic abnormalities and clonal evolution in an adult hepatoblastoma

Hepatoblastomas usually occur in children < 3 years of age, and only occasional adult cases have been described. To date, 20 cytogenetically abnormal childhood hepatoblastomas have been reported. Karyotypic investigations have shown that most hepatoblastomas are diploid or hyperdiploid, often displaying trisomies for chromosomes 2 and 20. We have cytogenetically investigated an adult hepatoblastoma for which no previous karyotypic data exist. A hypertriploid stemline with multiple numerical and structural chromosomal aberrations, including +2 and +20, was found. In addition, the tumor displayed extensive clonal evolution with 11 subclones. Although the tumor thus displayed some chromosomal abnormalities commonly observed in childhood tumors, providing further support for the importance of these abnormalities in the development of hepatoblastoma, the level of genomic complexity seen in the present case has never been described in childhood hepatoblastomas and may suggest a different etiology or pathogenesis.

Significance of extra copies of chromosome 20 and the long arm of chromosome 2 in hepatoblastoma

Cytogenetic analysis of both primary and metastatic hepatoblastoma revealed the following abnormal chromosomal complements respectively: 46,XX,der(2)t(2;2)(p25;q21),der(22)t(1;22)(q22;p13) [6]/47,XX,der(2)t(2;2)(p25;q21),+20,der(22)t(1;22)q22;p13)[4]/47,XX,der (2)t(2;2)(p25;q21), +20[1], and 48,XX,der(2)t(2;2)(p25;q21),+12,+17, -18,+20,der(22)t(1;22)(q22;p13)[9]/50,XX,der(2)t(2;2)(p25;q21), +8,+12,+17,+20[4]. Two abnormalities, the chromosome 2 derivative and trisomy 20, are recurrent in hepatoblastoma, but the derivative involving chromosomes 1 and 22 is a novel abnormality.

Absence of p53 gene mutation and infrequent overexpression of p53 protein in hepatoblastoma

Ten cases of hepatoblastoma were studied for overexpression of p53 protein by immunohistochemistry and for possible p53 gene mutation by single strand conformation polymorphism (SSCP) analysis and direct DNA sequencing of the polymerase chain reaction products. Only one case of the macrotrabecular type at stage IV showed overexpression of p53 protein. No DNA mobility shift was found in any of these cases studied by SSCP analysis. DNA sequencing performed on the case showing overexpression of p53 protein revealed no mutation within exons 5 to 8. The associated adrenal cortical carcinoma of the same case also showed overexpression of p53 protein, but no mutation of the p53 gene. These results indicate that mutation of the p53 gene is infrequent in hepatoblastoma. This observation supports the view that mutation of the p53 gene is not as important in the oncogenesis of childhood neoplasms as in adult cancers.

Primary liver tumours in children

An overview is presented of current management strategies in primary hepatic tumours in children. Recent advances include research in the genetic and molecular properties, especially of hepatoblastoma, the application of pre-operative chemotherapy, and the development of pre-surgical staging. Problem areas include management of relapse, chemotherapeutic drug resistance and multifocality. Hepatocellular carcinoma continues to have a much worse outcome than hepatoblastoma.