Clinical features of different isoforms of PML鄄RARα fusion gene in patients with acute promyelocytic leukemia / 白血病·淋巴瘤

Objective To explore the clinical features and prognosis of different PML_RARα fusion gene isoforms in acute promyelocytic leukemia (APL). Methods The clinical data of 78 patients initially diagnosed with APL in Fujian Medical University Union Hospital from February 2013 to July 2016 were collected. The clinical features and prognosis of different PML_RARα fusion gene isoforms were analyzed. Results There were 32 females (41%) and 46 males (59%) in 78 patients, with a median age of 40 years old (13-68 years old). The most common PML_RARα fusion gene was L type (48.7%, 38/78), followed by S type (46.2%, 36/78) and V type (5.1%, 4/78). The patients with white blood cell count more than 10×109/L (high_risk) occurred mostly in S type (61.1%, 22/36), compared with V type and L type, and there were statistically different (χ 2 ＝ 7.683, P < 0.05). A total of 78 patients included 8 cases (10.2%) of combined CD34 positive, 17 cases (21.8%) of combined FLT3_ITD mutation, 12 cases (15.4%) of combined DNMT3A mutation and 9 cases (11.5%) of additional chromosomal abnormalities. There were no significant differences in CD34 positive, FLT3_ITD, DNMT3A, and the incidence of additional chromosomal abnormalities among the three different isoforms (P＞0.05). The most common occurrence of retinoic acid syndrome (RAS) during treatment was S type (21/36), while rare for L type and V type (χ2＝ 7.633, P< 0.05). There were no statistical differences in the complete remission (CR) rate and disease_free survival rate among the patients with different PML_RARα isoforms (P＞0.05). Conclusions The clinical characteristics of different PML_RARα fusion gene isoforms are different, including most_common L type, more_common V type and S type in high risk groups; complicated RAS is commonly found in S type during the treatment. And different isoforms have no effect on the CR and DFS rate.

Acute promyelocytic leukemia with NPM鄄RARα fusion gene positive: report of one case and review of literature / 白血病·淋巴瘤

Objective To investigate the diagnosis, treatment and prognosis of acute promyelocytic leukemia (APL) with NPM_RARα fusion gene positive. Methods One APL patient with NPM_RARα fusion gene positive who was diagnosed by using morphology, immunology, cytogenetics, molecular biology and multiplex fluorescence in situ hybridization in Changhai Hospital in November 2014 was retrospectively analyzed, and the patient was induced with retinoic acid and treated with DA (daunorubicin + cytarabine) regimen, followed by 4 courses of cytarabine consolidation therapy. Results Abnormal promyelocyte accounted for 0.64 by morphology. And the group of cells expressed myeloperoxidase (MPO), CD13, CD15, CD117, and CD7, CD11c, CD79a, CD123 weakly expressed or not by immunophenotype analysis; karyotype analysis showed 45, XY, t(5;17), 7p-,-16[8]/46, idem,+20[5]/45, idem,-8,+20[2]/46, XY[5]; the fusion gene screening showed that the expression level of NPM_RARα was 416.98% compared with that of APL; molecular complete remission was obtained after the consolidation therapy, but the patient relapsed after 34 months. Finally, the patient died of abnormal coagulation and respiratory failure, with overall survival of 35 months. Conclusion APL with NPM_RARα fusion gene positive is a rare type of acute leukemia, and the main treatment method is retinoic acid combined with myeloid chemotherapy regimen, which has a favorable efficacy but a poor prognosis.

BRD4 interacts with PML/RARα in acute promyelocytic leukemia / 医学前沿

Bromodomain-containing 4 (BRD4) has been considered as an important requirement for disease maintenance and an attractive therapeutic target for cancer therapy. This protein can be targeted by JQ1, a selective small-molecule inhibitor. However, few studies have investigated whether BRD4 influenced acute promyelocytic leukemia (APL), and whether BRD4 had interaction with promyelocytic leukemia-retinoic acid receptor α (PML/RARα) fusion protein to some extent. Results from cell viability assay, cell cycle analysis, and Annexin-V/PI analysis indicated that JQ1 inhibited the growth of NB4 cells, an APL-derived cell line, and induced NB4 cell cycle arrest at G1 and apoptosis. Then, we used co-immunoprecipitation (co-IP) assay and immunoblot to demonstrate the endogenous interaction of BRD4 and PML/RARα in NB4 cells. Moreover, downregulation of PML/RARα at the mRNA and protein levels was observed upon JQ1 treatment. Furthermore, results from the RT-qPCR, ChIP-qPCR, and re-ChIP-qPCR assays showed that BRD4 and PML/RARα co-existed on the same regulatory regions of their target genes. Hence, we showed a new discovery of the interaction of BRD4 and PML/RARα, as well as the decline of PML/RARα expression, under JQ1 treatment.

Establishment of cell-based screening system for compound regulating the stability of retinoic acid receptors / 上海交通大学学报（医学版）

Objective·To establish a cell-based screening system for identification of compounds with activity in regulating retinoic acid receptor (RARα) stability. Methods·The modified pMSCV plasmid constructs, named as RARα-EGFP-IRES-DsRed, consists of enhanced green fluorescent protein (EGFP) fusing to RARα and red fluorescent protein (DsRed) as internal references incorporating the internal ribosome entry site (IRES) as interval sequence. The RARα-EGFP-IRES-DsRed plasmid was stably transfected into NB4 cells which were named as NB4-pMGIR-RARα. Fluorescence signals of EGFP and DsRed indirectly reflecting the expression of RARα, were detected by flow cytometry in cells that were treated with all-trans retinoic acid, sodium valproate, cytarabine, lenalidomide, etoposide, montelukast and gambogic acid, respectively. Effects of these compounds on the expression of RARα protein were further examined by Western blotting. Results·A double fluorescence reporter system for screening compounds that can increase the stability of RARα protein was successfully established, and sodium valproate was identified as a potent compound to promote the stability of RARα. Conclusion·The double fluorescence reporter system can be used to screen compounds regulating the stability of RARα protein, which can be further used to identify compounds regulating the stability of other proteins.

Characterizing PML/RARα Isoforms of Acute Promyelocytic Leukemia (APL) in Malay patients.

Aim: Reciprocal translocation between retinoic acid receptor alpha (RARα) gene on chromo- some 17 and promyelocytic leukemia (PML) gene on chromosome 15 is the hallmark for acute promyelocytic leukemia (APL). Three different PML/RARα isoforms have been described; S-form, L-form and V-form. Our aims were to characterize the different types of PML/RARα iso- forms in Malay patients with APL and to determine the outcome of these different types of iso- forms. Materials and methods: RT-PCR analysis was performed on 20 patients recruited from hematology-oncology ward. RT-PCR detected fusion transcript of PML/RARα in all patients. Results and Discussion: Of these patients, 65% (13 patients) exhibited L/V-form, and 35% (7 patients) S-form. Total white blood cell count (TWBC) was higher in L/V-form (25 x 109/l) compared to S-form (2.1 x 109/l) (p < 0.05). Five years survival rate was 100% and 33.3% for L/V-forms and S-forms respectively (p<0.005). Conclusion: We conclude that L/V- forms is the commonest isoform among Malays. They presented at younger age with higher TWBC counts. Although the sample size is small, our preliminary data showed an interestingly longer survival outcome among L/V-forms compared to S-form. PML/RARα isoforms could be used in future as risk stratification feature in patients diagnosed as APL. Further study with more number of patients is required.

CD34 positive-microgranular variant of acute promyelocytic leukemia in a child.

Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia (AML) in which abnormal promyelocytes predominate. APL is rare in children (approximately 10% of childhood AML) and is characterized by a higher incidence of hyperleukocytosis, an increased incidence of microgranular morphology, the presence of balanced t(15;17)(q22;q11.2-12) translocation, and more frequent occurrence of the PML-RARα isoforms bcr 2 and bcr 3 compared to adults. The cytomorphology of microgranular variant blasts is obviously different from AML M3 blasts; these cells have a nongranular or hypogranular cytoplasm or contain fine dust-like cytoplasmic azurophil granules that may not be apparent by light microscopy. This case report emphasizes the importance of a high index of suspicion for the diagnosis of APL, the hypogranular variant in particular. They are responsive to differentiation therapy with all trans-retinoic acid and complete remission in seen in >80% cases.

One case of acute promyelocytic leukemia with 3'RARα submicroscopic deletion / 白血病·淋巴瘤

Objective To report a rare case of M3r subtype of acute promyelocytic leukemia (APL)with 3'-end of RARα (3'RARα) submicroscopic deletion, and the characters of morphologic, cytogenetic,molecular genetic and molecular biology studies. Methods Chromosomes of bone marrow (BM) cells were prepared with direct method and short-term culture method, and R-banding technique was used for karyotypic analysis. Fluorescence in situ hybridization (FISH) assays were performed on fixed BM cells using the following specific DNA probes: CEP X/Y alpha satellite DNA probe, LSI PML-RARα dual-color dual-fusion and LSI RARα dual-color break apart probes. A quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) was performed to detect the PML-RARα transcript. A multiplex nested RT-PCR was also performed, which may simultaneously detect the fusion genes derived from 29 chromosomal aberrations in acute leukemia including PML-RARα, PLZF-RARα and NPM-RARα fusion transcripts. Results R-banding analysis revealed a karyotype of 45,X,-Y[6]/46,XY[8], FISH using CEP X/Y probe further confirmed Y-chromosome loss. FISH analysis with RARα dual-color break apart probe demonstrated a deletion of the entire 3'-end of one allele of RARα gene. Cytogenetic, FISH and RT-PCR analyses showed no PML-RARα,PLZF-RARα, NPM-RARα, NuMA-RARα and STAT5b-RARα rearrangements. Conclusion A new RARαrearrangement involving 3'RARα submicroscopic deletion in APL without X-RARα fusion has been identified.FISH analysis with RARα dual-color break apart probe is a useful method for characterization of this abnormality, but its molecular consequences remain to be elucidated.

Haematological & molecular profile of acute myelogenous leukaemia in India.

Background & objectives: Recurrent balanced translocations are generally recognized to be a major parameter for prognostication in acute myeloid leukaemia (AML). The chromosomal translocation t(15;17) results in PML/RARα fusion gene, t(8;21) results in AML1/ETO fusion gene and Inv 16 generates CBFβ/MYH11 fusion gene. Patients with these mutations have a good prognosis unlike abnormalities in chromosome 5 or 7 or FLT3 genes. Therefore, we screened the AmL patients for known specific genetic abnormalities that could lead to more definitive prognoses. Methods: A total of 113 AML patients were evaluated at diagnosis based on routine morphology and cytochemistry and classified according to the WHO criteria. The distribution of AML subtypes was M1(1), M2(32), M3(57), M4(14), M5(1), M6(1) and seven cases where morphological subtype could not be classified. RT-PCR was performed to identify PML/RARα, AML1/ETO, CBFβ/MYH11 and FLT3 internal tandem duplication (ITD). Results: Of the 57 patients with M3 subtype, 55 had the PML-RARα fusion transcript. The prevalence of bcr3 (short isoform) was higher (62%) than that of bcr1 (long isoform) (38%) and no correlation was found with age, sex or white blood cell count. FLT3 internal tandem duplication (ITD) mutations were more frequent in patients with APL than in other AML subtypes (17.5 vs. 8.9%), the frequency greater in patients with bcr3 isoform (70%) than in those with in bcr1 isoform (30%). Patients with FLT3/ITD mutations had a significantly higher median white cell count than those without these mutations (55 x 109/l vs. 6.3 x 109/l; P<0.001). More patients with FLT3/ITD mutations died early (53%) than those without these mutations (16%) (P<0.01). AML1-ETO fusion transcript was detected in 16 of 56 patients with no correlation with clinical or haematological parameters. Interpretation & conclusion: The results of the present study showed presence of bcr3 (short isoform) higher than bcr1 (long isoform). FLT3 internal tandem duplication (ITD) mutation was predominant in acute promyelocytic leukaemia patients with bcr3 isoform. Thus, patients with APL who have FLT3 mutation appear to have a poorer prognosis. Therefore, rapid identification of specific translocations at diagnosis is important for prognostic purposes and their detection should be incorporated into routine assessment.

Evaluation of the detection of PML-RARα fusion gene in acute promyelocytic leukemia to monitor minimal residual disease / 白血病·淋巴瘤

Objective To investigate the kinetics of PML-RARα fusion gene in acute promyelocytic leukemia(APL)to monitor minimal residual disease(MRD). Methods In induction therapy,consolidation and maintenance therapy courses, PML-RARα fusion gene was performed by RT-PCR. Results The long-term follow-up of 18 cases achieved complete remission (CR),two cases experienced molecular relapse. One case relapsed at 4 months after CR1 and achieved CR2 after induction therapy. However, molecular and hematology relapsed again at 2 months after CR2 and re-achieved CR3. The other case relapsed at 74 months after CR1 and achieved CR2 after induction treatment, who had survived for 106 months until the end of follow-up. Conclusion RT-PCR assay for detection of PML-RARα should be performed regularly during CR period so as to find molecular relapse eady. Hematological relapse could potentially be averted through treatment modification according to molecular monitoring results of PML-RARα.

Clinical study on two PML-RARα fusion gene isoforms in patients with acute promyelocytic leukemia / 白血病·淋巴瘤

Objective To illustrate the clinical relevance of distinct PML-RARα fusion gene isoforms in acute promyelocytic leukemia (APL). Methods The nested reverse transcriptase polymerase chain reaction (RT-PCR) was used to detect the long (L) or short (S) PML-RARα fusion gene isoforms in 92 newly diagnosed APL so as to evaluate the clinical feature, therapeutic reaction and prognosis of the two fusion gene isoforms. Results PML-RARα fusion gene was positive in all 92 APL patients, of which 52(56.5 %) was L type and 40 (43.5 %) was S type. There were no significant differences between L type and S type in the aspect of sex, age, white blood cell count,the percentage of bone marrow blasts plus promyeloeytes and chromosome before treatment. And there were no significant differences between the two isoforms in complete remission (CR) rate, the time of getting CR as well as the occurrence of retinoic acid syndrome (RAS), disseminated intravascular coagulation (DIC), intraeranial hemorrhage. Also, there were no significant differences in overall survival rate (OS) and relapse-free survival rate (RFS) between the two isoforms. Conclusion PML-RARα fusion gene isoforms in APL were not correlated with clinical therapeutic effect or prognosis.

Screening and Identification of The Proteins Interacting With NLS-RARα Protein / 生物化学与生物物理进展

Acute promyelocytic leukemia (APL) is characterized by the generation of the prototypic promyelocytic leukemia-retinoicacid receptor alpha (PML-RARα), an oncogenic fusion protein due to chromosomal translocation. In a human myeloid cell line,PML-RARα is cleaved by neutrophil elastase (NE) to produce the mutational PML [nuclear localization signal (NLS) deletion andRARα (NLS-RARα, containing NLS of PML), both of which may play an important role in APL pathogenesis. The yeast two-hybridtechnique was used to screen the intracellular proteins interacting with NLS-RARα, which may be involved in NLS-RARα signaling. The NLS-RARα coding sequence was amplified by polymerase chain reaction method and was cloned into the bait plasmid pGBKT7vector, which, after the confirmation by sequencing, was transformed into yeast AH109 and the subsequent expression of bait plasmidwas proved by Western-blot. The transformed yeast AH109 was mated with yeast Y187 (containing leukemia cDNA library plasmidspACT2) in medium. Diploid yeast was plated on synthetic dropout nutrient medium containing X-α-gal for screening. After beingreintroduced into yeast AH109 and sequenced to verify the expression of ORF, eight positive colonies were obtained, among whichonecontaining JTV-1 was cloned. The interaction between NLS-RARα and JTV-1 was further supported by indirect immunofluorescence,GST pull-down and co-immunoprecipitation, respectively. These findings brought some new clues for the further exploration ofNLS-RARα signaling to APL.

Advance in the pathogenesis and treatment of acute promyelocytic leukemia / 白血病·淋巴瘤

Pathogenesis of acute promyelocytic leukemia is one of the best understood disease among human hematological malignancies. Becasue of retinoic acid (RA) and arsenic trioxide which directly target the oncogenic promyelocytic leukemia-retinoic receptor A (PML-RARα) fusion protein, this disease became the first model for oncogene-targeted therapies.And other new therapy methods also gain great concern. The complexity of recent views of acute promyelocytic leukemia pathogenesis, as well as latest progress in clinical treatment were summarized and discussed in this review.

Value of interphase fluorescence in situ hybridization in diagnosing acute myeloid leukemia M2 and M3 / 肿瘤研究与临床

Objective To investigate the value of interphase fluorescence in situ hybridization(FISH)technique and the detection of fusion gene in the diagnosis of acute myeloid leukemia(AML)M2 and M3 Methods FISH was used to detect the AML1/ETO fusion gene and/or PML/RARα fusion gene in incipient cases including 9 AML-M2, 12 AML-M3 and 10 AML undetermined as AML-M2 or AML-M3 primarily diagnosed by routine morphology though bone marrow,cytochemical staining and immunophenotyping,which can help diagnose and guide clinical therapy.Results 4 of 9 AML-M2 cases were AML1/ETO positive.Among 12 AML-M3 cases,10 were PML/RARα positive.1 case was detected AML1/ETO fusion gene.In 10 untonfirmed M3 or M2,3 case8 showed AML1/ETO,5 showed PMIJRARot fusion gene and the rest showed neither of the genes.Conclusion As a new technique of the molecular genetics,FISH is accurate, rapid and efficient.It would be of significance not only at diagnosis of AML,but also for subsequent clinical decision-making.