Methylation of the 5' CpG island of the p16/CDKN2 tumor suppressor gene in normal and transformed human tissues correlates with gene silencing.

Loss of heterozygosity on 9p21, where the p16/CDKN2 tumor suppressor and the p15INK4B cell cycle regulator genes are located, is a common genetic alteration in bladder cancer. However, it has been difficult to demonstrate homozygous deletions and intragenic mutations in either of these two genes in primary transitional cell carcinomas (TCC) of the bladder. Similarly, colon cancer-derived cell lines have shown no homozygous deletions of the p16/CDKN2 locus in contrast to a wide variety of tumor-derived cell lines. We have investigated abnormal methylation of the 5' CpG islands of the p16/CDKN2 and p15INK4B genes as an alternative mechanism of inactivation of these genes in bladder and colon cancers. De novo methylation of the 5' CpG island of p16/CDKN2 was observed in 12 of 18 (67%) uncultured bladder TCCs and in 2 of 3 (67%) bladder cell lines. In contrast, only 1 of 10 (10%) colon carcinomas showed methylation of the 5' CpG island of p16/CDKN2. It was striking to find that this region was extensively methylated and the gene not expressed in the normal colonic mucosa of 6 of 10 (60%) patients with colon cancer, whereas 5 of the corresponding colon tumors showed no methylation and high levels of p16/CDKN2 expression. Our data show a significant correlation (P = 0.00001, two-sided) between the absence of p16/CDKN2 expression and methylation of its 5' CpG island in bladder tumors, cell lines, and normal colon mucosa. In contrast, no association was observed between expression and methylation status of the 5' CpG island of p15INK4B. Our results suggest that the p16/CDKN2 tumor suppressor gene may be inactivated by methylation of its 5' CpG island in TCCs of the bladder. We also present evidence of methylation of the 5' CpG island in this autosomal gene in normal colonic tissue.

Timing and magnitude of decline in alpha-fetoprotein levels in treated children with unresectable or metastatic hepatoblastoma are predictors of outcome: a report from the Children's Cancer Group.

PURPOSE: We analyzed data on 31 children with primary unresectable or metastatic hepatoblastoma (HB) to investigate possible prognostic correlations between the serum level of alpha-fetoprotein (AFP), its changes during treatment, and outcome. PATIENTS AND METHODS: Patients were treated according to the Children's Cancer Group (CCG) protocol 823F, which included an initial surgery before eight courses of chemotherapy that consisted of cisplatin immediately followed by a continuous infusion of doxorubicin. Four courses were given before and four after the second surgery. AFP levels were measured before treatment, before and after second surgery, and at the end of treatment. RESULTS: Twenty-four of 31 patients showed a decline of > or = 1 log in AFP levels before second surgery (early responders). By the end of treatment, there were 16 patients, all early responders, without clinical or radiographic evidence of tumor and with normal AFP levels. Fifteen of those 16 had a decline of > or = 2 logs in AFP before second surgery (large early response). Of the 15 patients who failed to respond to treatment, 10 died, among whom only one patient had a large early response. A large early response was the strongest independent predictor of outcome in a univariate and multivariate Cox regression model, and patients with such a response had the best survival (P < .0001). CONCLUSION: For children with unresectable or metastatic HB, early changes in AFP levels are a reliable predictor of outcome and can be used for identification of poor responders to treatment, ie, patients whose AFP level fails to decrease 2 logs before second surgery should be considered for alternative treatment.

Association of collagen type 1 alpha1 gene polymorphism with bone density in early childhood.

Osteoporosis is a disease characterized by the development of nontraumatic fractures, most commonly in the vertebrae of elderly women. Approximately 500,000 elderly women in the United States are newly diagnosed with vertebral fractures every year, as the compressive strength of the vertebra, mainly determined by the density of cancellous bone and its cross-sectional area, declines with age. A recent study in women suggested that a polymorphism in the Sp1 binding site of the collagen type I gene (COLIA1) was related to decreased vertebral bone mass and vertebral fractures. Determining the phenotypic trait(s) responsible for this relationship and whether this association is manifested in childhood would further define the structural basis for decreased bone mass and help identify children "at risk" for fractures later in life. We therefore studied the COLIA1 gene polymorphism and measurements of the size and the density of vertebral bone in 109 healthy, prepubertal girls. On average, 22 girls with the Ss genotype and one girl with the ss genotype had 6.7% and 49.4% lower cancellous bone density in the vertebrae than girls with the SS genotype. In contrast, there was no association between the size of the vertebrae and the COLIA1 genotypes.

Presence of p53 mutations in primary nasopharyngeal carcinoma (NPC) in non-Asians of Los Angeles, California, a low-risk population for NPC.

Mutatins of the p53 tumor suppressor gene are rare in nasopharyngeal carcinoma (NPC) patients who reside in high-risk areas, such as Southeastern China. Among this high-risk group, a pre-existing infection with the EBV and consumption of Cantonese salted fish are closely associated with NPC. We investigated the prevalence of p53 mutations in 28 primary NPC specimens from white (including Hispanic) and African-American patients in Los Angeles, who are at low risk for NPC. Using PCR-based single-strand conformational polymorphism and direct sequencing, we found four mutations (14%) in exons 5-8 of the p53 gene in four patients. All were C-to-T transition mutations: two were present in exon 5-one at codon 142 [CCT (Pro)-->CTT (Leu)] and another at codon 144 [CAG (Gln)-->TAG (stop codon)]. The other two mutations were identified in exon 8: one at codon 273 [CGT (Arg)-->CAT (His)], a CpG site, and one at codon 271, a silent mutation [GAG (Glu)-->GAA (Glu)]. This is the first report investigating the presence of p53 missense mutations in NPC among a low-risk population. Our data indicate that p53 is also an infrequent event among NPC patients at low risk for the disease.

Efficacy and safety of dasatinib in imatinib-resistant or -intolerant patients with chronic myeloid leukemia in blast phase.

Dasatinib is an inhibitor of BCR-ABL and SRC-family kinases for patients with imatinib-resistant or -intolerant chronic myelogenous leukemia (CML). In this international phase II trial, dasatinib was administered orally (70 mg twice daily) to patients with myeloid blast phase (MBP, n=109) or lymphoid blast phase (LBP, n=48) CML. After a minimum follow-up of 12 months (range 0.03-20.7 months), major hematologic responses were induced in 34% (MBP-CML) and 35% (LBP-CML) of patients. Major cytogenetic responses were attained in 33% (MBP-CML) and 52% (LBP-CML) of patients and complete cytogenetic responses were attained in 26 and 46%, respectively. Median progression-free survival was 6.7 (MBP-CML) and 3.0 (LBP-CML) months. Median overall survival was 11.8 (MBP-CML) and 5.3 (LBP-CML) months. Overall, dasatinib had acceptable tolerability. Fluid retention events were more frequent in the MBP-CML than the LBP-CML cohort: pleural effusion occurred in 36 and 13% (all grades) and 15 and 6% (grades 3/4), respectively. Other non-hematologic side effects were primarily grade 1/2; grade 3/4 events were recorded in

Melanotic neuroectodermal tumor of infancy. A case report of paratesticular primary with lymph node involvement.

A 17-month-old boy had a melanotic neuroectodermal tumor of infancy in the left paratesticular region affecting the retroperitoneal lymph nodes. Immunohistochemical and ultrastructural study showed phenotypical diversity of the proliferating cells within a spectrum of neuroectodermal differentiation. Urinary catecholamine levels were initially elevated but returned to normal values after complete eradication of the tumor. The patient received chemotherapy and is now well, without evidence of disease 28 months after surgery.

Vitamin D-receptor gene polymorphisms and bone density in prepubertal American girls of Mexican descent.

BACKGROUND: Bone mass is under strong genetic control, and recent studies in adults have suggested that allelic differences in the gene for the vitamin D receptor may account for inherited variability in bone mass. We studied the relations of the vitamin D-receptor genotype to skeletal development and variation in the size, volume, and density of bone in children. METHODS: We identified three allelic variants of the vitamin D-receptor gene using the polymerase chain reaction and three restriction enzymes (ApaI, BsmI, and TaqI) in 100 normal prepubertal American girls of Mexican descent. We then determined the relations of the different vitamin D-receptor genotypes (AA, Aa, aa, BB, Bb, bb, TT, Tt, and tt) to the cross-sectional area, cortical area, and cortical bone density of the femoral shaft and the cross-sectional area and density of the lumbar vertebrae. RESULTS: The vitamin D-receptor genotype was associated with femoral and vertebral bone density. Girls with aa and bb genotypes had 2 to 3 percent higher femoral bone density (P=0.008 and P=0.04, respectively) and 8 to 10 percent higher vertebral bone density (P=0.01 and P=0.03, respectively) than girls with AA and BB genotypes. There was no association between the cross-sectional area of the vertebrae or the cross-sectional or cortical area of the femur and the vitamin D-receptor genotype. The chronologic age, bone age, height, weight, body-surface area, and body-mass index did not differ significantly among girls with different vitamin D-receptor genotypes. CONCLUSIONS: Vitamin D-receptor gene alleles predict the density of femoral and vertebral bone in prepubertal American girls of Mexican descent.