Takeshi Kusafuka

Inversely correlated expression of p16 and Rb protein in non‐small cell lung cancers: An immunohistochemical study

Cdk4‐mediated phosphorylation of Rb protein is inhibited by p16, a product of a possible tumor suppressor gene. We examined the expression of p16 and Rb protein by means of immunohistochemistry in 61 non‐small cell lung cancers and have demonstrated an inverse relationship between the expression of p16 and Rb protein: 28/30 specimens that did not stain for p16 stained for Rb and 21/31 p16‐positive specimens did not stain for Rb. Only 1 of the p16‐negative specimens had a mutation of exon 2 of the CDKN2 gene. Our results indirectly support the theory that p16 expression is negatively regulated by the functional Rb protein.

Immunohistochemical expression of MMP-2, MMP-9, and TIMP-2 in neuroblastoma : Association with tumor progression and clinical outcome

BACKGROUND/PURPOSE The matrix metalloproteinases (MMPs) are responsible for degradation of the extracellular matrix. The MMPs and their specific tissue inhibitor metalloproteinases (TIMP) have been associated with tumor cell invasion and metastasis in a number of adult tumors. This study was carried out to detect their expression pattern in neuroblastoma and to evaluate whether they have any association with tumor progression and clinical outcome. METHODS Cryostat sections of tumor tissues were collected from 31 patients with neuroblastoma, and immunohistochemical staining of MMP-2, MMP-9 and TIMP-2 with specific antibodies was performed according to labelled streptavidin-biotin method. RESULTS MMP-2 and MMP-9 were coexpressed in neuroblastoma and exhibited an intratumor variability of staining intensity. MMP-2 and MMP-9 staining were confined mostly to the peritumoral stromal tissues rather than tumor cells and found positive in 80.6% cases and 71.0% cases, respectively. MMP-2 and MMP-9 immunoreactivity had no association with mass screened cases or with age of the patients. Increased expression of MMP-2 in stromal tissues of neuroblastoma had significant association with advanced clinical stages (chi2 test, P < .05). However, the expression of MMP-9 in neuroblastoma had no association with clinical stages and prognosis. However, TIMP-2 staining was confined mostly to the neoplastic cell cytoplasm, stromal tissue, and to the endothelial cells and accounted for 58.0% positivity. Decreased expression of TIMP-2 also had significant relationship with advanced clinical stages (chi2 test, P < .05). Kaplan-Meier survival curve showed that either increased expression of MMP-2 or decreased expression of TIMP-2 had relationship with poor clinical outcome. CONCLUSIONS In neuroblastoma, stromal tissues are actively involved in the complex interaction between MMP-2 and TIMP-2 in extracellular matrix degradation during tumor progression, and TIMP-2 expression is inversely correlated with the corresponding MMP-2. An early detection of their expression pattern by immunohistochemistry in neuroblastoma may provide prognostic informations in clinical practice.

High frequency of β-catenin mutations in hepatoblastoma

Abstract. Hepatoblastoma (HB) is an embryonic neoplasm representing the most frequent malignant liver tumour in childhood. Its tumourigenesis at the molecular level is still poorly understood, and candidate genes are yet to be identified. According to recent reports describing β-catenin mutations (BCM) at hot-spot regions involving exon 3 in several types of malignancies including HB, we investigated BCM in 16 HBs classified into different histological types. One tumour had been previously confirmed to harbour adenomatous polyposis coli (APC) mutations that exhibit a similar oncogenic effect to that of BCM. Mutations in both exon 3 and its flanking region of the β-catenin gene were investigated and determined. Twelve tumours (75%) revealed pathogenic BCM, including 5 with missense mutations at codons 32, 34, or 37 and 7 with interstitial deletions that partially or totally affected exon 3. All 7 deletions were in-frame deletions without frame shift. A single nucleotide change at codon 31 regarded as non-pathogenic polymorphism was detected in the tumour possessing APC mutations. Therefore, a total of 13 tumours (81%) were compromised by an enhanced β-catenin-mediated transcription pathway. Mutations were observed in every histological type of HB. The very high frequency without correlation to histological type indicates that BCM are crucial events in the tumourigenesis of HB.

Mutation analysis of the RET, the endothelin-B receptor, and the endothelin-3 genes in sporadic cases of Hirschsprung's disease☆

To date, three genes have been identified as susceptibility genes for Hirschsprungs disease (HSCR), the RET proto-oncogene, the endothelin-B receptor gene (EDNRB) and the endothelin-3 gene (EDN3). However, the question of whether these genes play a role in sporadically occurring HSCR has not been fully clarified. In this study, the authors performed mutation analysis of these three genes in 41 sporadic HSCR patients without any family history by using single-strand conformational polymorphism or denaturing gradient gel electrophoresis methods. Exon 2, 3, 5, 6, 12, 13, 15, and 17 of the RET gene, 7 exons of the EDNRB gene, and the region of the EDN3 gene including sequences corresponding to proteolytic cleavage sites and mature endothelin-3 were analysed. By direct sequencing, three causative RET mutations were confirmed; a Phe to Ser substitution at codon 174, a Cys to Tyr substitution at codon 197, and a point mutation at the splice acceptor site of intron 12, in patients with aganglionosis confined to the rectosigmoid colon, the transverse colon, and the total colon, respectively. In the EDNRB locus, two mutations were observed; a nonsense mutation of Trp to stop at codon 275, and a T insertion at nucleotide 878, in patients with aganglionosis confined to the rectosigmoid colon, and the descending colon, respectively. No mutation was detected in the EDN3 gene. Mutation rates were 7.3% in the RET and 5% in the EDNRB gene. Our data indicate that RET and EDNRB mutations have a role in the aetiology of some sporadically occurring HSCR. However, the low mutation rate of susceptibility genes in sporadically occurring HSCR suggests that other genes or environmental factors are involved in the development of the disease.

In situ detection of DNA fragmentation and expression of bcl-2 in human neuroblastoma: relation to apoptosis and spontaneous regression.

UNLABELLED Spontaneous regression occurs in some cases of neuroblastoma, especially stage IVS. The incidence of neuroblastoma has been reported to be increasing since the mass screening program was introduced in Japan. This would indicate that the screening is detecting regressing tumors. However, the mechanism of regression is still unknown. To evaluate the hypothesis that the regression might be related to apoptosis, the authors examined apoptosis by in situ end-labeling of fragmented DNA and expression of the apoptosis-suppressing protein bcl-2. MATERIALS AND METHODS One hundred eighteen neuroblastoma cases were available for examination. Eighty (67.8%) were detected by the mass screening program. Serial sections were cut from paraffin-embedded tumors. A modified TdT-mediated dUTP nick end-labeling (TUNEL) method was performed to detect apoptosis. Immunohistochemical analysis was performed to detect bcl-2 expression. RESULTS In cases under 1 year of age or with a favorable clinical stage, the incidence of apoptosis was significantly high. Expression of bcl-2 was associated with N-myc amplification and unfavorable histology (Shimada classification). Tumors in patients under 1 year of age often had areas where cellularity was markedly decreased, and apoptosis was often observed while bcl-2 expression was reduced. In such cases, there was a negative correlation between occurrence of apoptosis and bcl-2 expression. This suggests that apoptosis may be related to spontaneous regression in neuroblastoma.

Transcatheter arterial chemoembolization in the treatment of hepatoblastoma

BACKGROUND The prognosis of hepatoblastoma is poor unless the tumor is completely resected. Various types of chemotherapy have been developed to increase its resectability. Recently, transcatheter arterial chemoembolization (TACE) has been developed for the treatment of unresectable adult hepatoma with favorable results. The authors applied this procedure to hepatoblastoma in infants and children. METHODS TACE was performed in eight hepatoblastoma cases. After an intraarterial catheter was inserted into the main feeding artery of the tumor, injection of adriamycin or THP-adriamycin (20 to 30 mg/m2) dispersed in lipiodol and cisplatin (40 to 60 mg/m2) followed by embolization using Gelfoam pieces was performed. Effects of TACE were evaluated according to shrinkage of tumor mass on imaging examinations, alpha-fetoprotein (AFP) levels, and pathological findings of the surgical specimens 4 weeks after TACE. RESULTS A marked reduction in tumor size associated with a decrease in AFP level occurred 1 month after the treatment. Tumor shrinkage ranged from 0.9% to 45.0% with a mean value of 25.8%. AFP levels decreased by 0.2% to 11.9% with a mean level of 4.6% from initial levels. In addition, there was no marked chemotherapeutic agent-induced toxicity noted during the observation period. Resection of the tumors was performed safely after TACE in all cases. Pathological examination showed massive necrosis in the surgical specimens, and the mean percentage of necrotic area within the tumor was 71.1%. Two patients died of extensive lung metastasis 2 months and 3 years after the operation, respectively. The remaining six were doing well and free of disease at a mean follow-up period of 50 months. CONCLUSION TACE is an effective, safe, and useful method for the initial treatment of hepatoblastoma.

Mutations of the endothelin-B receptor and endothelin-3 genes in Hirschsprung's disease

The endothelin-B receptor gene (EDNRB) and the endothelin-3 gene (EDN3) have recently been recognized as susceptibility genes for Hirschsprungs disease (HD). Novel EDNRB mutations have been detected in non-syndrommc HD patients with heterozygous forms, and homozygous mutations of the EDNRB or the EDN3 genes have been reported in HD patients associated with type 2 Waardenburg syndrome. These observations confirm that impaired function of the endothelin-B receptor or endothelin-3 is involved in the aetiology of some human HD cases. EDNRB mutations appear to be associated with shortsegment HD, in contrast to RET mutations, which are found mainly in long-segment aganglionosis.

p53 gene mutations in pleuropulmonary blastomas

Pleuropulmonary blastoma (PPB) is rarechildhoodtumororiginating fromeitherlung orpleura. Although several cytogenetic changes, such as trisomy 2, trisomy 8, and loss of 17p material, have been reported, evidence of gene mutations is still lacking. Pathologically, PPB shares similarities with rhabdomyosarcoma in which p53 mutations are frequently detected. Possible implication of p53 mutations in PPB was investigated. PPBs of 3 patients were analyzed for occurrence of p53 mutations by using polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) method, and the nature of mutations was confirmed by direct sequencing. Two PPBs were confirmed to harbor p53 mutations. One was a Val to Leu substitution at codon 173, and another was a ArgArg to TrpCys substitution at codons 282 and 283. In each tumor, only the mutated allele was detected, suggesting inactivation of p53. Both patients with mutations had fatal outcome, while the remaining patient in whom no mutation was detected is disease free for 3 years after completion of treatment. The results raise the possibility that p53 inactivation can occur as a nonrandom genetic change involving the pathogenesis and outcome of PPB. Further studies in a larger series are necessary to clarify these matters.

Genetic Aspects of Hirschsprung's Disease

Hirschsprungs disease (HD) is a relatively common cause of intestinal obstruction in the newborn, characterized by the absence of autonomic ganglion cells in the terminal bowel. Existence of familial cases indicates that genetic factors may be involved in the etiology of some cases of HD. Different inheritance patterns observed in subsets of HD families or kindreds, and the detection of different chromosome aberrations in some HD patients, suggest genetic heterogeneity of HD. Recent expansion of molecular genetics has identified multiple susceptibility genes of HD. These include the RET gene, the glial cell-derived neurotrophic factor gene, the endothelin-B receptor gene, and endothelin-3 gene. Furthermore, some other genes or genetic factors are speculated to be implicated in the development of HD, and it is believed that multiple factors play a role in disease development in some cases. Taken together, these data suggest and may explain the complexity of the etiology of HD. This review focuses on recent advances in our understanding of the genetic aspects of HD.

Renal cell carcinoma in a pediatric patient with an inherited mitochondrial mutation

Renal cell carcinoma (RCC) is a rare pediatric renal cancer. Recent molecular genetic studies discovered a tumor-specific mutation involving translocation of a transcription factor TFE3 in a subset of pediatric RCC with distinct histopathology. We reported a case of a 2-year-old boy with RCC associated with TFE3 translocation resulting in a PRCC-TFE3 fusion gene. Interestingly, the case carried a maternally inherited mitochondrial DNA (mtDNA) alteration at the position which is usually found in MELAS (Mitochondrial Encephalopathy, Lactic Acidosis, and Stroke-like Episodes) syndrome (A3243G). Although evidence of somatic alterations in mtDNA existed in various cancers, association between inherited mtDNA mutation and pediatric renal cancer has not been reported. Our case provided the first evidence of a co-occurrence between a germ line mutation in mtDNA and the somatic mutation of pediatric RCC. With this information, we speculated a role of mitochondria mutation in the pathogenesis of this cancer.