Altered expression of MALAT1 lncRNA in chronic lymphocytic leukemia patients, correlation with cytogenetic findings

BACKGROUND: Recent studies have devoted much attention to non-protein-coding transcripts in relation to a wide range of malignancies. MALAT1, a long non-coding RNA, has been reported to be associated with cancer progression and prognosis. Thus, we here determined MALAT1 gene expression in chronic lymphocytic leukemia (CLL), a genetically heterogeneous disease, and explored its possible relationships with cytogenetic abnormalities. METHODS: MALAT1 expression level was evaluated using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) on blood mononuclear cells from 30 non-treated CLL patients and 30 matched healthy controls. Cytogenetic abnormalities were determined in patients by fluorescence in situ hybridization (FISH). RESULTS: MALAT1 expression level was up-regulated in the CLL group compared to healthy controls (P=0.008). Del13q14, followed by Del11q22, were the most prevalent cytogenetic abnormalities. We found no association between the FISH results and MALAT1 expression in patients. CONCLUSION: Altered expression of MALAT1 is associated with CLL development. Further investigations are required to assess the relationship between this long non-coding RNA and CLL patient survival and prognosis.

association between PARP1 and LIG3 expression levels and chromosomal translocations in acute myeloid leukemia patients

Objective: Chromosomal translocations are among the most common mutational events in cancer development, especially in hematologic malignancies. However, the precise molecular mechanism of these events is still not clear. It has been recently shown that alternative non-homologous end-joining [alt-NHEJ], a newly described pathway for double-stranded DNA break repair, mediates the formation of chromosomal translocations. Here, we examined the expression levels of the main components of alt-NHEJ [PARP1 and LIG3] in acute myeloid leukemia [AML] patients and assessed their potential correlation with the formation of chromosomal translocations

Materials and Methods: This experimental study used reverse transcription-quantitative polymerase chain reaction [RT- qPCR] to quantify the expression levels of PARP1 and LIG3 at the transcript level in AML patients [n=78] and healthy individuals [n=19]

Results: PARP1 was the only gene overexpressed in the AML group when compared with healthy individuals [P=0.0004], especially in the poor prognosis sub-group. Both genes were, however, found to be up-regulated in AML patients with chromosomal translocations [P=0.04 and 0.0004 respectively]. Moreover, patients with one isolated translocation showed an over-expression of only LIG3 [P=0.005], whereas those with two or more translocations over-expressed both LIG3 [P=0.002] and PARP1 [P=0.02]

Conclusion: The significant correlations observed between PARP1 and LIG3 expression and the rate of chromosomal translocations in AML patients provides a molecular context for further studies to investigate the causality of this association

Cytogenetic and FMS-like tyrosine kinase 3 mutation analyses in acute promyelocytic leukemia patients

The secondary genetic changes other than the promyelocytic leukemia-retinoic acid receptor [PML-RARA] fusion gene may contribute to the acute promyelocytic leukemogenesis. Chromosomal alterations and mutation of FLT3 [FMS-like tyrosine kinase 3] tyrosine kinase receptor are the frequent genetic alterations in acute myeloid leukemia. However, the prognostic significance of FLT3 mutations in acute promyelocytic leukemia [APL] is not firmly established. In this study, the chromosomal abnormalities were analyzed by bone marrow cytogenetic in 45 APL patients and FLT3 internal tandem duplications [ITD] screening by fragment length analysis and FLT3 D835 mutation by melting curve analysis were screened in 23 APL samples. Cytogenetic study showed 14.3% trisomy 8 and 17.1% chromosomal abnormalities other than t[15;17]. About 13% of the patients had FLT3 ITD, and 26% had D835 point mutation. FLT3 ITD mutation was associated with higher white blood cell count at presentation and poor prognosis. The PML-RARA translocation alone may not be sufficient to induce leukemia. Therefore, we assume that FLT3 mutations and the other genetic and chromosomal alterations may cooperate with PML-RARA in the development of APL disease

Frequency of BCR-ABL fusion transcripts in Iranian patients with chronic myeloid leukemia

A specific chromosomal abnormality, the Philadelphia chromosome, is present in 90 - 95% of patients with chronic myeloid leukemia. The aberration results from a reciprocal translocation of chromosomes 9 and 22, creating a BCR-ABL fusion gene. There are two major forms of the BCR-ABL fusion gene, involving ABL exon 2, but including different exons of BCR gene. The transcript b2a2 or b3a2 codes for a p210 protein. Other fusion gene leads to the expression of an e1a2 transcript, which codes for a p190 protein. Other less common fusion genes are b3a3 or b2a3 [p203] and e19a2 [p230]. The incidence of one or other rearrangement in chronic myeloid leukemia patients varies in different reports. In general, fusion transcripts are determined individually, a process which is labor- intensive in order to detect all major fusion transcripts. The objective of this study was to set up a multiplex RT-PCR assay for detection and to determine the frequency of different fusion genes in 75 Iranian patients with chronic myeloid leukemia. Peripheral blood samples were analyzed by multiplex RT-PCR from 75 adult Iranian chronic myeloid leukemia patients to detect different types of BCR-ABL transcripts of the t[9;22]. All patients examined were positive for some type of BCR/ABL rearrangement. The majority of the patients [83%] expressed one of the p210BCR-ABL transcripts [b3a2, 62% and b2a2, 20%], while the remaining showed one of the transcripts of b3a3, b2a3, e1a2 or co-expression of b3a2 and b2a2. The rate of co-expression of the b3a2 and b2a2 was 5%. In contrast to other reports, we did not see any co-expression of p210/p190. Co-expression may be due to alternative splicing or to phenotypic variation, with clinical course different from classic chronic myeloid leukemia