Distinct forms of tyrosine kinase domain (TKD), juxtamembrane domain, exon 8, and internal tandem duplication (ITD) mutations of c-KIT, were observed in about 46% of core binding factor leukemia (CBFL) patients. To evaluate their prognostic significance, 67 adult patients with CBFL were analyzed to ascertain the c-KIT mutation status. In acute myeloid leukemia (AML) with t(8;21), the presence of c-KIT TKD mutation at codon 816 (TKD 816 ) was associated with a high white blood cell count at diagnosis (median, 29.60 ؋ 10 9 /L) and a higher incidence (33%) of extramedullary leukemia (EML) during the course of the disease. Data also showed that the TKD 816 mutated patients (n ‫؍‬ 12) had a significantly higher incidence of relapse and a lower overall survival (OS) at 24 months, compared with the 17 c-KIT unmutated (c-KIT ؊ ) patients (90% vs 35.3%, P ‫؍‬ .002; 25% vs 76.5%, P ‫؍‬ .006, respectively). No difference in relapse incidence (P ‫؍‬ .126) and OS (P ‫؍‬ .474) was observed between the c-KIT mutated other than TKD 816 (n ‫؍‬ 7) and the c-KIT ؊ patients. These findings indicate that c-KIT TKD 816 mutation has a negative impact on the outcome of AML with

Genetic analysis identifies the HMMR gene as a modifier of the breast cancer risk associated with BRCA1 gene mutation, while cell biological analysis of the protein product suggests a function in regulating development of the mammary gland.

The SH2 domain-containing tyrosine phosphatase PTPN6 (SHP-1, PTP1C, HCP) is a 68 kDa cytoplasmic protein primarily expressed in hematopoietic cell development, proliferation and receptor-mediated mitogenic signaling pathways. By means of direct dephosphorylation, it down-regulates a broad spectrum of growth-promoting receptors, including the Kit tyrosine kinase, activated to elicit a prominent cascade of intracellular events by stem cell factor binding. The pivotal contribution of PTPN6 in modulating myeloid cell signaling has been revealed by the finding that shp-1 mutation is responsible for the overexpansion and inappropriate activation of myelomonocytic populations in motheaten (me/me) and motheaten viable (me(v)/me(v)) mice. Association of PTPN6 with c-Kit and negative modulation of the myeloid leukocyte signal transduction pathways prompted us to examine the expression of the protein tyrosine phosphatase PTPN6 gene in CD34(+)/CD117(+) blasts from acute myeloid leukemia patients. We identified and cloned cDNAs representing novel PTPN6 mRNA species, derived from aberrant splicing within the N-SH2 domain leading to retention of intron 3. Sequence analysis of cDNA clones revealed multiple A-->G editing conversions. The editing of PTPN6 mRNA mainly occurred as an A-->G conversion of A(7866), which represents the putative branch site in IVS3 of PTPN6 mRNA. Evidence that editing of A(7866) abrogates splicing has been obtained in vitro by using an edited clone and its backward clone generated by site-directed mutagenesis. The level of the aberrant intron-retaining splice variant, evaluated by semi-quantitative RT-PCR, was lower in CD117(+)-AML bone marrow mononuclear cells at remission than at diagnosis, suggesting the involvement of post-transcriptional PTPN6 processing in leukemogenesis.

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This pharmacologic therapy is effective and well tolerated; it could become a routine in clinical practice to improve the supportive care of patients with taste alterations resulting from head and neck cancer.