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Background and Objective: Sex chromosome loss (SCL) can occur in older men as a physiological phenomenon or as an acquired abnormality in leukemia. Loss of chromosome Y and loss of chromosome X are acquired disorders that are mainly observed in patients over 80 years as well as in myeloid and lymphoid malignancies. In this review, we examine the cytogenetic and molecular changes of sex chromosomes in leukemia., Methods: Relevant English language literature were searched and retrieved from PubMed search engine (1990-2016). The following keywords were used: 'Sex chromosomes', 'Leukemia' and 'Cytogenetics'., Results: The loss of tumor suppressor genes along with these chromosomal abnormalities in the majority of malignant cells in bone marrow (BM) has raised the question whether this is an age-related phenomenon or has occurred as a result of clonal abnormality. On the other hand, the presence of these chromosomal abnormalities in a number of genetic diseases associated with leukemia leads to progression of malignancy, and their role in peripheral blood stem cell transplantation confirm the finding that these chromosomal abnormalities can play an important role in clonal abnormality., Conclusion: The presence of these abnormalities can cause genetic instability in BM and result in the development of a malignant clone and progression of the disease. In addition, the evaluation of SCL together with the genes involved in these chromosomes can contribute to predict the disease prognosis as well as monitoring of malignancy.

Objective: Bone marrow (BM) niche is a three-dimensional structure composed of a series of cells and it is one of the most controversial topics in hematological malignancies, leukemia, and even metastasis. Here, we review the relationship between Notch signaling and different fates of stem cells and other BM niche cells., Methods: Relevant English-language literature were searched and retrieved from PubMed (2000-2013) using the terms Notch signaling, BM niche, and microRNAs (miRNAs)., Discussion: Notch signaling pathway is a signaling system involved in cellular processes such as proliferation, differentiation, and apoptosis. The notch signaling pathway components are associated with interaction between leukemic, metastatic, and normal cells and their microenvironment. miRNAs play an important role in expression and regulation of signaling molecules. It is necessary to evaluate the relationship between aberrant miRNA expression and notch signaling such as miR-128 and miR-30 in glioma and angiogenesis with notch signaling, respectively., Conclusions: Characterizing malignant cells and future studies focus on better understanding the variety of cancers and apoptosis with activated Notch signaling pathway, may remain promising this signaling system as a safe and effective therapeutic target.

Introduction: Acute lymphoblastic leukemia (ALL) cells have unique rearranged immunoglobulin heavy chain (IgH), immunoglobulin light chain (IgK), and T-cell receptor (TCR) genes, which can be used as markers for clonality assay and evaluation of minimal residual disease. In this study, we have evaluated the pattern of IgH, IgK chains, and TCRG/D gene rearrangements in precursor-B ALL., Materials and Methods: In our prospective study, hyper-variable regions (CDRI and III) of IgH, TCRD (Vδ2-Dδ3 and Dδ2-Dδ3), TCRG (Vγ, VγI, and VγII), and IgK (Vκ-Kde) were studied in 126 cases with diagnosis of B-precursor ALL., Results: One hundred and fourteen (90.5%) out of 126 patients had clonal rearrangements of IgH using consensus primers for CDRI and/or CDRIII regions. Monoclonal, biclonal, and oligoclonal patterns were observed in 63 (57.8%), 38 (34.9%), and 6 (5.5%) patients with IgH (CDRIII) rearrangements, respectively. Clonal rearrangements of TCRG (Vγ) and VγI/II were present in 79.3 and 64.9% of patients, respectively, and only 5% of cases showed biclonal pattern. The VγII rearrangement was the most common (46.8%) type in TCRG. Vδ2-Dδ3 and Dδ2-Dδ3 partial gene rearrangements were observed in 47 (45.2%; n = 104) and 11 (16.6%; n = 66) patients, respectively. Biclonal/oligoclonal patterns were present in 13 (27.7%) and 2 (4.3%) cases with Vδ2-Dδ3 rearrangement, respectively. Only one patient had biclonal Dδ2-Dδ3 rearrangement. Clonal pattern of IgK-Kde was detected in 59 cases (67%; n = 88)., Conclusion: Our findings showed that clonal rearrangements of IgH and TCRD (Vδ2-Dδ3 and Dδ2-Dδ3) genes had similar patterns to other studies. Frequency of TCRG (VγI and VγII) and IgK rearrangements was found to be slightly higher than previous reports. Among the IgK rearrangements, VKI (25%) was the most common.

Objectives: Neoplastic niche is a specific microenvironment for growth and proliferation of malignant cells. Here we review the leukemic niche and its constituent stem cells, signaling pathways and essential chemokines., Methods: Relevant literature was identified by a PubMed search (2000-2013) of English-language literature using the terms neoplastic niche, chemokines, and leukemia., Discussion: Leukemia is caused by malignant hematopoietic stem cells and precursors. Important molecules and signals are involved in interactions between leukemic cells and their microenvironment. MicroRNAs (miRNAs) play an important role in expression regulation of oncogenes, transcription factors, signaling molecules and in eventual fate of the cell. It seems necessary to evaluate the relationship between aberrant miRNA expression and malignant transformation of bone marrow niche., Conclusions: Characterizing malignant leukemic cells, activated signaling pathways, and molecules involved in disease progression will result in understanding the causes of drug resistance, relapse factors, and effective treatments.