Deletion of the short arm of chromosome 9 (9p), resulting in the loss of the p16INK4a/MTS1 gene, now called CDKN2, has been found to occur frequently in acute lymphoblastic leukemia, even in the absence of a microscopically visible deletion.
Inverse correlation between loss of heterozygosity of the short arm of chromosome 12 and p15ink4B/p16ink4 gene inactivation in childhood acute lymphoblastic leukaemia.
We identified homozygous deletion of p16 and p15 genes in five (19%) of 27 acute lymphoblastic leukemias (ALLs) and in two (11%) of 19 acute myeloid leukemias (AMLs).
Particular attention will be paid to the data concerning the incidence of p16INK4A (and p15INK4B) gene(s) inactivation in human acute lymphoblastic leukemias.
Finally, dexamethasone (Dex) induced apoptosis of JKB p16MT cells cultured at 40 degrees C, but did not trigger death of these cells cultured at 31 degrees C. These results suggest that deletion of p16 gene in JKB human ALL cells is associated with dysregulated growth of less differentiated tumor cells, which nonetheless remain susceptible to apoptosis triggered by Dex.
Patients with ALL who expressed pRb had a higher probability and patients who expressed p16 a lower probability of remaining in first continuous remission, but the results were not statistically significant.
The results showed ALL-1 gene rearrangements in 15/22 (68%) cases, p53 gene mutations in 5/22 (26%), and a homozygous deletion of p16 in a single T-ALL case. p53 and p16 alterations were all found in the group of patients with ALL-1 gene rearrangements. p53 mutations were more often associated with a myeloid phenotype (3/5).
Our preliminary findings on eight pediatric patients with acute lymphoblastic leukemia (ALL) suggested that the survival of patients carrying a homozygous p16 gene deletion was significantly inferior to that of those without a deletion.
The p16INK4A (p16) and p15INK4B (p15) tumor suppressor genes are inactivated by homozygous gene deletion and p15 promoter hypermethylation in a significant proportion of childhood acute lymphoblastic leukemias (ALLs).
Further, by characterizing the roles of translocation-generated fusion genes (TEL-AML 1) and tumor suppressor genes (p15INK4B and p16INK4A) in treatment response, it may be possible to identify new and selective targets and/or treatment strategies for both children and adults with ALL who are refractory to current therapies.
We studied bone marrow samples of 42 newly diagnosed and untreated patients with acute lymphoblastic leukemia for the incidence of deletions of p16INK4a/p14ARF and p15INK4b using Southern blot analysis and determined the clinical outcome with regard to complete remission (CR) duration, event-free survival, and overall survival.
We therefore analyzed the clinical and biological implications of this feature by studying p16ink4a expression in 58 cases of childhood ALL. mRNA and protein were significantly correlated and both appeared more highly expressed in B than in T lineage ALLs: 13 out of the 15 T cell ALLs did not show any p16ink4a expression.
In vitro sensitivity of T-cell lymphoblastic leukemia to UCN-01 (7-hydroxystaurosporine) is dependent on p16 protein status: a Pediatric Oncology Group study.
Inverse correlation between Ink4-locus deletions and ICM-DNA hyperdiploidy in childhood acute lymphoblastic leukaemia, relation to clinical characteristics and outcome.
The contribution of INK4a deletions to the progression of B-lineage ALL is uncertain, partially due to a paucity of data on expression in normal B-cell precursors.
In this study, 25 paediatric patients with ALL were analysed at diagnosis and relapse for their p16 (exon 2) status using the most accurate method of detection, real-time polymerase chain reaction (PCR).
The methylation-specific polymerase chain reaction (MS-PCR) was used to analyze p15 and p16 gene methylation in 49 cases of acute lymphoblastic leukemia (ALL) and 29 cases of acute myelogenous leukemia (AML).
These findings suggest that p16INK4a ICC and deletion analysis provide distinct information about ALL cells and that the simple ICC method may be of prognostic value in standard risk adult ALL.
A broad spectrum of tumor suppressor gene alterations do occur in hematological malignancies, especially structural alterations of p15(INK4A), p15(INK4B) and p14(ARF) in acute lymphoblastic leukemia as well as methylation of these genes in several myeloproliferative disorders.
Loss of heterozygosity of p16 correlates with minimal residual disease at the end of the induction therapy in non-high risk childhood B-cell precursor acute lymphoblastic leukemia.