Improved survival of patients with acute lymphoblastic leukemia (ALL) has emerged from identifying new prognostic markers; however, 20% of children still suffer recurrence. Previously, the altered expression of Fat1 cadherin has been implicated in a number of solid tumors. In this report, in vitro analysis shows that Fat1 protein is expressed by a range of leukemia cell lines, but not by normal peripheral blood (PB) and bone marrow (BM) cells from healthy donors. In silico analysis of expression of array data from clinical leukemias found significant levels of Fat1 transcript in 11% of acute myeloid leukemia, 29% and 63% of ALL of B and T lineages, respectively, and little or no transcript present in normal PB or BM. Furthermore, in two independent studies of matched diagnosis --relapse of precursor B-cell (preB) ALL pediatric samples (n ¼ 32 and n ¼ 27), the level of Fat1 mRNA expression was prognostic at the time of diagnosis. High Fat1 mRNA expression was predictive of shorter relapse-free and overall survival, independent of other traditional prognostic markers, including white blood cell count, sex and age. The data presented demonstrate that Fat1 expression in preB-ALL has a role in the emergence of relapse and could provide a suitable therapeutic target in high-risk preB-ALL.Leukemia ( INTRODUCTIONChildren with acute lymphoblastic leukemia (ALL) continue to suffer a 20% incidence of relapse after treatment with the best available therapy. High-resolution genomic profiling, including analysis of single-nucleotide polymorphisms and copy number abnormalities, has greatly aided an understanding of the molecular mechanisms underlying treatment outcome, therapy response and the biology of relapse. 1,2 For precursor B-cell (preB) ALL, genomic studies have shown that copy number abnormalities in genes involved in lymphoid differentiation and cell cycle control are common, with deletions, or part thereof, found in PAX5, EBF1, IKZF1, TCF-4, CDKN2A and RB1. 2 --5 Recent reports also indicate that deletions and nonsense mutations of the IKZF1 gene are significantly associated with poor relapse-free and overall survival rates in preB-ALL. 6 However, in light of these studies, questions remain on the biology of relapse, with marker analysis complicated by the fact that phenotypic shifts in preB-ALL blasts can occur between diagnostic and post-chemotherapy or relapse samples. 7 Those cells that give rise to relapse in some cases appear to be selected during treatment, with clonal evolution occurring of a minor subclone present at diagnosis rather than simply being the development of chemotherapeutic resistance of the original leukemic clone. 8,9 The inherent genetic heterogeneity

The giant cadherin FAT1 is one of four vertebrate orthologues of the Drosophila tumor suppressor fat. It engages in several functions, including cell polarity and migration, and in Hippo signaling during development. Homozygous deletions in oral cancer suggest that FAT1 may play a tumor suppressor role, although overexpression of FAT1 has been reported in some other cancers. Here we show using Northern blotting that human melanoma cell lines variably but universally express FAT1 and less commonly FAT2, FAT3, and FAT4. Both normal melanocytes and keratinocytes also express comparable FAT1 mRNA relative to melanoma cells. Analysis of the protein processing of FAT1 in keratinocytes revealed that, like Drosophila FAT, human FAT1 is cleaved into a non-covalent heterodimer before achieving cell surface expression. The use of inhibitors also established that such cleavage requires the proprotein convertase furin. However, in melanoma cells, the non-cleaved proform of FAT1 is also expressed at the cell surface together with the furin-cleaved heterodimer. Moreover, furin-independent processing generates a potentially functional proteolytic product in melanoma cells, a persistent 65-kDa membrane-bound cytoplasmic fragment no longer in association with the extracellular fragment. In vitro localization studies of FAT1 showed that melanoma cells display high levels of cytosolic FAT1 protein, whereas keratinocytes, despite comparable FAT1 expression levels, exhibited mainly cell-cell junctional staining. Such differences in protein distribution appear to reconcile with the different protein products generated by dual FAT1 processing. We suggest that the uncleaved FAT1 could promote altered signaling, and the novel products of alternate processing provide a dominant negative function in melanoma.

Borderline ovarian tumors represent an understudied subset of ovarian tumors. Most studies investigating aberrations in borderline tumors have focused on KRAS/BRAF mutations. In this study we conducted an extensive analysis of mutations and single nucleotide polymorphisms in borderline ovarian tumors. Using the Sequenom MassARRAY platform we investigated 160 mutations/polymorphisms in 33 genes involved in cell signalling, apoptosis, angiogenesis, cell cycle regulation, and cellular senescence. Of 52 tumors analysed, 33 were serous, 18 mucinous and 1 endometrioid. KRAS c.35G>A p.Gly12Asp mutations were detected in 8 tumors (6 serous and 2 mucinous), BRAF V600E mutations in 2 serous tumors, and PIK3CA H1047Y and PIK3CA E542K mutations in a serous and an endometrioid BOT respectively. CTNNB1 mutation was detected in a serous tumor. Potentially functional polymorphisms were found in VEGF, ABCB1, FGFR2 and PHLPP2. VEGF polymorphisms were the most common and detected at 4 loci. PHLPP2 polymorphisms were more frequent in mucinous as compared to serous tumors (p=0.04), with allelic imbalance in one case. This study represents the largest and most comprehensive analysis of mutations and functional single nucleotide polymorphisms in borderline ovarian tumors to date. At least 25% of borderline ovarian tumors harbour somatic mutations associated with potential response to targeted therapeutics.

Corticotropin Releasing Hormone (CRH), a 41-amino acid peptide, is a major regulator of hypothalamic-pituitary-adrenal axis function. CRH also has important roles in several processes pertaining to pregnancy and parturition, including being a possible regulator of gestational length and predictor of pre-term birth. Regulation of the CRH promoter exhibits some tissue-specificities, the most well characterized example being glucocorticoids, which can stimulate placental CRH production but suppress hypothalamic CRH. In the last decade there has been growing interest in the role of epigenetic regulation of gene expression. Modification of the structure of chromatin is an example of epigenetic change affecting gene expression. We have found that inhibition of histone deacetylases results in an increase in CRH expression in the AtT20 pituitary cell line, but a decrease in CRH expression in the placenta. In this paper we review tissue specific differences in CRH gene expression, and discuss how epigenetic chromatin modification mechanisms can relate to tissue specific differences in expression of CRH.