Shigeyuki Furuta

Identification and characterization of a 500-kb homozygously deleted region at 1p36.2-p36.3 in a neuroblastoma cell line

Loss of heterozygosity of the distal region of chromosome 1p where tumor suppressor gene(s) might harbor is frequently observed in many human cancers including neuroblastoma (NBL) with MYCN amplification and poor prognosis. We have identified for the first time a homozygously deleted region at the marker D1S244 within the smallest region of overlap at 1p36.2-p36.3 in two NBL cell lines, NB-1 and NB-C201 (MASS-NB-SCH1), although our genotyping has suggested the possibility that both lines are derived from the same origin. The 800-kb PAC contig covering the entire region of homozygous deletion was made and partially sequenced (about 60%). The estimated length of the deleted region was 500 kb. We have, thus far, identified six genes within the region which include three known genes (DFF45, PGD, and CORT) as well as three other genes which have been reported during processing our present project for the last 3½ years (HDNB1/UFD2, KIAA0591F/KIF1B-β, and PEX14). They include the genes related to apoptosis, glucose metabolism, ubiquitin-proteasome pathway, a neuronal microtubule-associated motor molecule and biogenesis of peroxisome. At least three genes (HDNB1/UFD2, KIAA0591F/KIF1B-β, and PEX14) were differentially expressed at high levels in favorable and at low levels in unfavorable subsets of primary neuroblastoma. Since the 1p distal region is reported to be imprinted, those differentially expressed genes could be the new members of the candidate NBL suppressor, although RT-PCR-SSCP analysis has demonstrated infrequent mutation of the genes so far identified. Full-sequencing and gene prediction for the region of homozygous deletion would elucidate more detailed structure of this region and might lead to discovery of additional candidate genes.

The usefulness of laryngotracheal separation in the treatment of severe motor and intellectual disabilities

Intractable aspiration is a life-threatening medical problem in patients with severe motor and intellectual disabilities (SMID). Laryngotracheal separation (LTS) is a surgical procedure for the treatment of intractable aspiration which separates the upper respiratory tract from the digestive tract. We performed LTS for 14 patients with SMID to prevent intractable aspiration, performing two types of operation. The standard diversion procedure connected the upper trachea to the esophagus. The modified diversion includes closure of the proximal trachea and a high tracheostomy, avoiding a tracheoesophageal anastomosis. LTS was performed on 14 patients. Operations performed before the LTS included tracheostomy in four patients, fundoplication in six and gastrostomy in two. A standard diversion was performed in 11 patients and a modified diversion in 3. There were no operative complications. Eleven patients were safely transferred to home-care after their LTS. Twelve patients are still alive and two died some months after operation. One patient died from their primary disease and the other died a tracheo-innominate artery fistula (TIAF). We recently experienced a patient who was at high risk of developing a TIAF. LTS is an effective operation, preventing intractable aspiration in patients with severe motor and intellectual disabilities. The results are similar for the standard or modified diversion procedure with the procedure chosen being related to the initial tracheostomy site. The most serious complication is a lethal TIAF.

Analysis of loss of heterozygosity at 16p12-p13 (familial neuroblastoma locus) in 470 neuroblastomas including both sporadic and mass screening tumors

BACKGROUND Neuroblastoma (NBL) in children usually occurs in a sporadic form. However, it rarely occurs in families. Recently, the familial neuroblastoma (FNB) locus has been mapped to 16p12-p13 by linkage analysis. PROCEDURE Here we show the result of loss of heterozygosity in the region spanning 16p12-p13 (D16S406-D16S409, 46 cM) in 470 NBLs including both sporadic and mass screening cases. RESULTS Allelic loss was found in 61(13%) tumors. Deletion of 16p was associated with mass screening tumor (P = 0.035) and <1 year of age at diagnosis (P = 0.048). We found two commonly deleted regions: the sizes of the region were approximately 2 cM and approximately 6 cM. CONCLUSIONS Our data suggested that allelic loss of 16p was common in favorable NBLs, and there may be at least two candidate loci within the region of FNB.

Identification of the homozygously deleted region at chromosome 1p36.2 in human neuroblastoma

BACKGROUND We have identified for the first time a homozygously deleted region within the smallest region of overlap at 1p36.2-3 in two neuroblastoma cell lines. PROCEDURE The 800-kb PAC contig covering the entire homozygously deleted region was made and sequenced. To date, approximately 70% of sequencing has been accomplished, and the estimated length of the deleted region was 500 kb. RESULTS Currently, we have found six genes within the region, which include three known genes as well as three other genes that have been reported during processing of our present project for the last 3(1/2) years. We report here the results of expression and mutation analyses of those genes. CONCLUSIONS Full sequencing for the region of homozygous deletion as well as further analyses of the genes mapped within the region may reveal whether or not there is a neuroblastoma suppressor gene as proposed by the Knudsons two-hit hypothesis.