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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.

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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.

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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.

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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.

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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.

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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.