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author:("corradino, F")
1.  Expression of p89c-Mybex9b, an alternatively spliced form of c-Myb, is required for proliferation and survival of p210BCR/ABL-expressing cells 
Blood Cancer Journal  2012;2(5):e71-.
The c-Myb gene encodes the p75c-Myb isoform and less-abundant proteins generated by alternatively spliced transcripts. Among these, the best known is pc-Mybex9b, which contains 121 additional amino acids between exon 9 and 10, in a domain involved in protein–protein interactions and negative regulation. In hematopoietic cells, expression of pc-Mybex9b accounts for 10–15% of total c-Myb; these levels may be biologically relevant because modest changes in c-Myb expression affects proliferation and survival of leukemic cells and lineage choice and frequency of normal hematopoietic progenitors. In this study, we assessed biochemical activities of pc-Mybex9b and the consequences of perturbing its expression in K562 and primary chronic myeloid leukemia (CML) progenitor cells. Compared with p75c-Myb, pc-Mybex9b is more stable and more effective in transactivating Myb-regulated promoters. Ectopic expression of pc-Mybex9b enhanced proliferation and colony formation and reduced imatinib (IM) sensitivity of K562 cells; conversely, specific downregulation of pc-Mybex9b reduced proliferation and colony formation, enhanced IM sensitivity of K562 cells and markedly suppressed colony formation of CML CD34+ cells, without affecting the levels of p75c-Myb. Together, these studies indicate that expression of the low-abundance pc-Mybex9b isoform has an important role for the overall biological effects of c-Myb in BCR/ABL-transformed cells.
PMCID: PMC3366069  PMID: 22829973
transcription factor; oncogene; chronic myeloid leukemia
2.  An intronic mutation in MLH1 associated with familial colon and breast cancer 
Familial Cancer  2010;10(1):27-35.
Single base substitutions can lead to missense mutations, silent mutations or intronic mutations, whose significance is uncertain. Aberrant splicing can occur due to mutations that disrupt or create canonical splice sites or splicing regulatory sequences. The assessment of their pathogenic role may be difficult, and is further complicated by the phenomenon of alternative splicing. We describe an HNPCC patient, with early-onset colorectal cancer and a strong family history of colorectal and breast tumors, who harbours a germ line MLH1 intronic variant (IVS9 c.790 +4A>T). The proband, together with 2 relatives affected by colorectal-cancer and 1 by breast cancer, have been investigated for microsatellite instability, immunohistochemical MMR protein staining, direct sequencing and Multiplex Ligation-dependent Probe Amplification. The effect of the intronic variant was analyzed both by splicing prediction software and by hybrid minigene splicing assay. In this family, we found a novel MLH1 germline intronic variant (IVS9 c.790 +4A>T) in intron 9, consisting of an A to T transversion, in position +4 of the splice donor site of MLH1. The mutation is associated with the lack of expression of the MLH1 protein and MSI in tumour tissues. Furthermore, our results suggest that this substitution leads to a complete skip of both exon 9 and 10 of the mutant allele. Our findings suggest that this intronic variant plays a pathogenic role.
PMCID: PMC3036834  PMID: 20717847
Intronic mutation; MLH1; Minigene assay; Colon cancer; Breast cancer

Results 1-2 (2)