t(3;7)(q26;q21) CDK6/MECOM

2016-07-01   Jean Loup Huret 

1.Medical Genetics, Dept Medical Information, University Hospital, F-86021 Poitiers, France. Jean-loup.huret@chu-poitiers.fr

Abstract

Review on t(3;7)(q26;q21), with data on clinics, and the genes involved.

Clinics and Pathology

Disease

Myeloid malignancies.

Phenotype stem cell origin

Fifteen cases are available (Tien et al., 1989; Henzan et al., 2004; Storlazzi et al., 2004; Madrigal et al., 2006; Bobadilla et al., 2007; Colovic et al., 2011; Haferlach et al., 2012). There were 4 chronic myelogenous leukemia in blast crisis (CML-BC), one myelodysplastic syndrome (MDS) and 10 acute myeloid leukemia (AML) cases.

Epidemiology

t(3;7)(q26;q21) represented about 1% of a cohort of 606 AML and 377 MDS patients with normal karyotypes (n = 594) or chromosome 7 alterations (-7/7q-; n = 389). Median age was 51 years (range 47-70) (Haferlach et al., 2012). In 6 other patients, ages were, 18, 41, 56, 58, 61 and 71 years. Of 7 cases with data on the patientsex; there were 6 male and 1 female patient.

Cytogenetics

Cryptic rearrangement.

Prognosis

Poor prognosis. Survival outcomes in 22 patients with cryptic MECOM rearrangements (der(7)t(3;7)(q26;q21), inv(3)(p24q26), and t(3;21)(q26;q11), altogether) were compared with inv(3)(q21q26)/t(3;3)(q21;q26) cases. Median overall survival was 9.4 months in the subgroup with cryptic MECOM rearrangements which was not significantly different from the 21.8 months in patients with an inv(3)(q21q26)/t(3;3)(q21;q26) (Haferlach et al., 2012). The 3 other patients with t(3;7)(q26;q21) and survival data died 4, 6, and 26 months after diagnosis.

Genes Involved and Proteins

Gene name
MECOM (Ecotropic Viral Integration Site 1 (EVI1) and Myelodysplastic Syndrome 1 (MDS1-EVI1)
Location
3q26.2
Note
MECOM is a nuclear transcription factor that plays an essential role in the proliferation and maintenance of hematopoietic stem cells and can inhibit myeloid differentiation. Two alternative forms exists, one generated from EVI1, the other MECOM (MDS1 and EVI1 complex locus) through intergenic splicing with MDS1 (myelodysplasia syndrome 1), a gene located 140 kb upstream of EVI1.
Protein description
The protein encoded by this gene is a transcriptional regulator involved in cell differentiation and proliferation, and apoptosis. The encoded protein can interact with transcriptional coactivators (P/CAF, CBP) and corepressors (CTBP1, HDAC) as well as other transcription factors (GATA1, Smad3) (de Braekeleer et al., 2012)
Gene name
CDK6 (cyclin dependent kinase 6)
Location
7q21.2
Protein description
Serine/threonine-protein kinase; it was regarded as a mere homolog of CDK4 with overlapping functions in the initiation of the cell cycle. CCND1 (cyclin D1) is an activator of CDK4/ CDK6. CDK4 and CDK6 associate with D-type cyclins, to go through from the G1 phase to the S phase. CDK6 is overexpressed and/or amplified in leukemias and lymphomas, glioblastoma and pancreatic cancer. CDK6 can regulate transcription independently of its kinase activity (Tigan et al., 2016).

Result of the Chromosomal Anomaly

Oncogenesis

Increased MECOM expression was noted.

Bibliography

Pubmed IDLast YearTitleAuthors
173412662007An interphase fluorescence in situ hybridisation assay for the detection of 3q26.2/EVI1 rearrangements in myeloid malignancies.Bobadilla D et al
217750972011Therapy-related myelodysplastic syndrome and acute myeloid leukemia in patients with chronic lymphocytic leukemia treated with fludarabine and cyclophosphamide.Colović M et al
228878042012Three novel cytogenetically cryptic EVI1 rearrangements associated with increased EVI1 expression and poor prognosis identified in 27 acute myeloid leukemia cases.Haferlach C et al
153227642004Myeloid/natural killer cell blast crisis representing an additional translocation, t(3;7)(q26;q21) in Philadelphia-positive chronic myelogenous leukemia.Henzan H et al
170119812006Fluorescence in situ hybridization studies using BAC clones of the EVI1 locus in hematological malignancies with 3q rearrangements.Madrigal I et al
145517382004A novel chromosomal translocation t(3;7)(q26;q21) in myeloid leukemia resulting in overexpression of EVI1.Storlazzi CT et al
27311521989Chromosomal characteristics of Ph-positive chronic myelogenous leukemia in transformation. A study of 23 Chinese patients in Taiwan.Tien HF et al
265000592016CDK6-a review of the past and a glimpse into the future: from cell-cycle control to transcriptional regulation.Tigan AS et al

Summary

Fusion gene

CDK6/MECOM

Citation

Jean Loup Huret

t(3;7)(q26;q21) CDK6/MECOM

Atlas Genet Cytogenet Oncol Haematol. 2016-07-01

Online version: http://atlasgeneticsoncology.org/haematological/1672/t(3;7)(q26;q21)-cdk6-mecom

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