A NUP98-positive acute myeloid leukemia with a t(11;12)(p15;q13) without HOXC cluster gene involvement

RARG Gene Dysregulation in Acute Myeloid Leukemia

Retinoic acid receptor γ (RARγ) belongs to the nuclear receptor superfamily and shares 90% homology with retinoic acid receptor α (RARα) and retinoic acid receptor β (RARβ). RARA rearrangements are well-known to be involved in acute promyelocytic leukemia (APL), but RARG rearrangements can also resemble this kind of leukemia. In this review we trace the role of RARγ, considering both its physiological and oncogenic contribution; from 2011 to date, nine cases of patients harboring RARG fusions have been reported. These patients showed typical APL features, including the clinical presentation, coagulation abnormalities and morphological features of bone marrow (BM), but are not responsive to APL standard therapy. We stress the urgent need for a better comprehension of the critical role of RARG dysregulation in the leukemogenesis process, since optimum therapy strategies have not yet been established.

The Pleiotropic Role of Retinoic Acid/Retinoic Acid Receptors Signaling: From Vitamin A Metabolism to Gene Rearrangements in Acute Promyelocytic Leukemia

The family of retinoic acid receptors (RARs: RARα, -β, and -γ) has remarkable pleiotropy characteristics, since the retinoic acid/RARs pathway is involved in numerous biological processes not only during embryonic development, but also in the postnatal phase and during adulthood. In this review, we trace the roles of RA/RARs signaling in the immune system (where this pathway has both an immunosuppressive role or is involved in the inflammatory response), in hematopoiesis (enhancing hematopoietic stem cell self-renewal, progenitor cells differentiation or maintaining the bone marrow microenvironment homeostasis), and in bone remodeling (where this pathway seems to have controversial effects on bone formation or osteoclast activation). Moreover, in this review is shown the involvement of RAR genes in multiple chromosomal rearrangements generating different fusion genes in hematological neoplasms, with a particular focus on acute promyelocytic leukemia and its variant subtypes. The effect of different RARs fusion proteins on leukemic transformation, on patients’ outcome, and on therapy response is also discussed.

Paralogous HOX13 Genes in Human Cancers

Hox genes (HOX in humans), an evolutionary preserved gene family, are key determinants of embryonic development and cell memory gene program. Hox genes are organized in four clusters on four chromosomal loci aligned in 13 paralogous groups based on sequence homology (Hox gene network). During development Hox genes are transcribed, according to the rule of “spatio-temporal collinearity”, with early regulators of anterior body regions located at the 3’ end of each Hox cluster and the later regulators of posterior body regions placed at the distal 5’ end. The onset of 3’ Hox gene activation is determined by Wingless-type MMTV integration site family (Wnt) signaling, whereas 5’ Hox activation is due to paralogous group 13 genes, which act as posterior-inhibitors of more anterior Hox proteins (posterior prevalence). Deregulation of HOX genes is associated with developmental abnormalities and different human diseases. Paralogous HOX13 genes (HOX A13, HOX B13, HOX C13 and HOX D13) also play a relevant role in tumor development and progression. In this review, we will discuss the role of paralogous HOX13 genes regarding their regulatory mechanisms during carcinogenesis and tumor progression and their use as biomarkers for cancer diagnosis and treatment.

Acute monocytic leukaemia with t(11; 12) (p15; q13) chromosomal changes: A case report and literature review

Acute myeloid leukaemia (AML) is a type of heterogeneous disease derived from haematopoietic stem cells. Cytogenetic characterisation is essential for diagnosis and prognosis stratification. Here, we present the case of a 43-year-old female diagnosed with leukaemia, who demonstrated a rare chromosomal change of t(11; 12) (p15; q13) along with a positive FLT3-ITD mutation. The patient had a white blood cell count of 76.41×10⁹/l. Bone marrow morphology revealed that monoblasts accounted for 25.5% of cells, and premonocytes accounted for 49.0%. This patient strongly responded to idarubicin and Ara-c (cytarabine) chemotherapy, which rapidly eliminated the leukaemia cell clones. However, the proliferation rate of the leukaemia cells was high during the intermission of chemotherapy. Subsequently, following two courses of chemotherapy, full haematological remission could not be attained. AML patients with t(11; 12) (p15; q13) combined with FLT3-ITD mutations are expected to have a short life expectancy; however, early haematopoietic stem cell transplantation therapy may improve the treatment outcome for these patients.

NUP98/11p15 translocations affect CD34+ cells in myeloid and T lymphoid leukemias

We assessed lineage involvement by NUP98 translocations in myelodysplastic syndromes (MDS), acute myeloid leukaemia (AML), and T-cell acute lymphoblastic leukaemia (T-ALL). Single cell analysis by FICTION (Fluorescence Immunophenotype and Interphase Cytogenetics as a Tool for Investigation of Neoplasms) showed that, despite diverse partners, i.e. NSD1, DDX10, RAP1GDS1, and LNP1, NUP98 translocations always affected a CD34+/CD133+ hematopoietic precursor. Interestingly the abnormal clone included myelomonocytes, erythroid cells, B- and T- lymphocytes in MDS/AML and only CD7+/CD3+ cells in T-ALL. The NUP98-RAP1GDS1 affected different hematopoietic lineages in AML and T-ALL. Additional specific genomic events, were identified, namely FLT3 and CEBPA mutations in MDS/AML, and NOTCH1 mutations and MYB duplication in T-ALL.

Characterization of chromosome 11 breakpoints and the areas of deletion and amplification in patients with newly diagnosed acute myeloid leukemia

Chromosome 11 abnormalities are found in many hematological malignancies. In acute myeloid leukemia (AML), a proto-oncogene MLL (11q23.3) is frequently altered. However, rearrangements involving other regions of chromosome 11 have been reported. Therefore, we have characterized the chromosome 11 breakpoints and common deleted and amplified areas in the bone marrow or peripheral blood cells of newly diagnosed patients with AML. Using molecular-cytogenetic methods (multicolor fluorescence in situ hybridization (mFISH), multicolor banding (mBAND), microarrays, and FISH with bacterial artificial chromosome (BAC) probes, chromosome 11 abnormalities were delineated in 54 out of 300 (18%) newly diagnosed AML patients. At least 36 different chromosome 11 breakpoints were identified; two were recurrent (11p15.4 in the NUP98 gene and 11q23.3 in the MLL gene), and three were possibly nonrandom: 11p13 (ch11:29.31-31.80 Mb), 11p12 (ch11:36.75-37.49 Mb) and 11q13.2 (68.31-68.52 Mb). One new MLL gene rearrangement is also described. No commonly deleted region of chromosome 11 was identified. However, some regions were affected more often: 11pter-11p15.5 (n = 4; ch11:0-3.52 Mb), 11p14.1-11p13 (n = 4; ch11:28.00-31.00 Mb) and 11p13 (n = 4; ch11:31.00-31.50 Mb). One commonly duplicated (3 copies) region was identified in chromosomal band 11q23.3-11q24 (n = 9; ch11:118.35-125.00 Mb). In all eight cases of 11q amplification (>3 copies), only the 5' part of the MLL gene was affected. This study highlights several chromosome 11 loci that might be important for the leukemogeneic process in AML.

A novel NUP98/RARG gene fusion in acute myeloid leukemia resembling acute promyelocytic leukemia

Chromosomal translocations in hematological malignancies often result in novel fusion chimeric genes. We report a case of acute myeloid leukemia with a clonal translocation t(11;12)(p15;q13) displaying morphologic and immunophenotypic features resembling the classical hypergranular subtype of acute promyelocytic leukemia. The gene fused to NUP98 (nucleoporin 98) was detected by comparative genomic hybridization array as the retinoid acid receptor gamma gene (RARG). The involvement of RARG in a chimeric fusion transcript has not been reported previously in human leukemia.