<i>CDKN2A/2B</i> deletions were associated with poor 2-year OS (P=0.045) and RFS (P=0.071) rates in Philadelphia chromosome positive (Ph<sup>+</sup>) B-ALL patients, as well as in the high risk (HR) B-ALL group (P=0.037 and P=0.047, respectively).
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.
Aberrant expression of tumor suppressor genes WT 1, RB 1, p53, homozygous deletion of p16 gene and their relationship with expression of oncogenes BCR-ABL, TEL-AML 1, MLL-AF 4, E2A-PBX 1, SIL-TAL 1 were determined in bone marrow samples of children with de novo B-lineage (n=170) and T-lineage (n=25) acute lymphoblastic leukemia (ALL).
Although the ABL kinase inhibitor imatinib mesylate (Gleevec) provides highly effective treatment for BCR-ABL-positive chronic myelogenous leukemia, it has proven far less efficacious in the treatment of BCR-ABL-positive acute lymphoblastic leukemias (ALLs), many of which sustain deletions of the INK4A-ARF (CDKN2A) tumor suppressor locus.
Association of genetic variation in IKZF1, ARID5B, CDKN2A, and CEBPE with the risk of acute lymphoblastic leukemia in Tunisian children and their contribution to racial differences in leukemia incidence.
At diagnosis, p15 methylation occurred in 29 (58%) AML patients, and 10 (40.0%) ALL patients. p16 methylation occurred in two (4%) AML and two (8%) ALL patients.
At the 9p arm is located the p16 (MTS1) TSG and probably others with an effect on various human tumours such as acute lymphoblastic leukaemia, bladder cancer, gliomas, malignant mesotheliomas, melanomas and non-small cell lung carcinomas.
Common CNAs involved CDKN2A/2B (30.3%), IKZF1 (27.3%), PAX5 (9.1%), RB1 (9.1%), BTG1 (6.7%), and ETV6 (6.7%), which regulate cell cycle, B lymphopoiesis, or act as tumor suppressors in ALL.
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.
Deletions of EBF1, IKZF1, and CDKN2A/B have an independent adverse prognosis for adolescents and adults with B-precursor ALL, and this suggests that these CNAs should be included in the initial risk assessment of ALL.
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.
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.
Homozygous deletions of p16 exons were found in 5 of 10 (50%) patients with CML in lymphoid BC and in 5 (26%) ALL patients, but in only 1 (2%) case with AML.
Homozygous deletions of p16/MTS1 and p15/MTS2 genes are frequent in t(1;19)-negative but not in t(1;19)-positive B precursor acute lymphoblastic leukemia in childhood.
Homozygous MTS2 deletions were observed in 16 of 24 T-ALL cases and in 1 of 31 B-lineage ALLs (P < .001), all of them displaying homozygous MTS1 deletions.
In ALL an association of homozygous deletions of p16ink4a and p15ink4b, and T-lineage, 9p abnormalities, and prognostic factors was found in some but not all reports.