MicroRNA-125b Accelerates and Promotes PML-RARa-driven Murine Acute Promyelocytic Leukemia / 生物医学与环境科学（英文）

Objective@#Most acute promyelocytic leukemia cases are characterized by the PML-RARa fusion oncogene and low white cell counts in peripheral blood.@*Methods@#Based on the frequent overexpression of miR-125-family miRNAs in acute promyelocytic leukemia, we examined the consequence of this phenomenon by using an inducible mouse model overexpressing human miR-125b.@*Results@#MiR-125b expression significantly accelerates PML-RARa-induced leukemogenesis, with the resultant induced leukemia being partially dependent on continued miR-125b overexpression. Interestingly, miR-125b expression led to low peripheral white cell counts to bone marrow blast percentage ratio, confirming the clinical observation in acute promyelocytic leukemia patients.@*Conclusion@#This study suggests that dysregulated miR-125b expression is actively involved in disease progression and pathophysiology of acute promyelocytic leukemia, indicating that targeting miR-125b may represent a new therapeutic option for acute promyelocytic leukemia.

CLINICOPATHOLOGICAL STUDY OF ACUTE PROMYELOCYTIC LEUKEMIA: AN EXPERIENCE FROM A TEACHING HOSPITAL IN INDIA

Data on the clinicopathological features of acute promyelocytic leukemia (APL) patients from India is limited. Present study was a cross sectional study which included 18 patients of APL. Medical records of these 18 patients were reviewed to collect their clinical details and laboratory results. High risk patients (total leucocyte count >10,000/cmm) were treated with modified APML 4 protocol.Low risk patients (total leucocyte count <10,000/cmm) were treated with protocol APL- 0406-Intergroup Study AL WP GIMEMA-DSIL protocol. Outcomes in terms of complete remission were assessed in both these groups. Mean haemoglobin levels was 7.03gm%, mean total leucocyte count was 30,462per cmm, mean platelet count was 27,222/cmm. Bone marrow was reported as suggestive of APL in 17 cases while in 1 case, BM aspirate was inadequate. Average percentage of abnormal promyelocytes in bone marrow was 84.25%. PT was prolonged in 15 cases, while APTT was prolonged in 3 cases. Flow cytometry analysis was done in 12 patients. All patients were CD45, MPO, CD13, CD33 and CD64 positive. Chromosomal analysis was possible in 11 cases. t(15;17)(q22;21) was identified in 6 cases (54.62%). 3 cases (27.27%) showed normal karyotype. 2 (18.18%) cases had additional cytogenetic abnormalities. All patients under high risk category attained CR. 1 patient under low risk category with additional cytogenetic abnormality died 6 days after induction therapy was started. 10 (55.55%) patients developed complications such as neutropenic sepsis, intracranial hemorrhage, differentiation syndrome, cerebral venous sinus thrombosis, pseudotumorcerebri, QTc interval prolongation, and pneumonia.

Tetraploid/near-tetraploid acute promyelocytic leukaemia with double (15;17) translocation

@#A 57-year-old man presented with intermittent fever and bleeding following dental surgery. Peripheral smear and bone marrow aspirate exhibited unusually large and bizarre-looking abnormal cells which were found to be myeloblasts with aberrant CD56 and CD2 expression on immunophenotyping. Fluorescence in situ hybridization analysis revealed an extra RARA gene rearrangement. This finding correlated well with a near-tetraploid karyotype with double t(15;17)(q22;q21). Bcr-3 type PML/ RARA copies were identified in reverse transcriptase-polymerase chain reaction. The diagnosis of near-tetraploid acute promyelocytic leukaemia (APML) was established. The patient was treated with all-trans retinoic acid and idarubicin and six weeks later achieved complete remission. Tetraploid/ near-tetraploid APML is exceedingly rare. It is a distinct cytogenetic subgroup with unique clinical and biological features as highlighted by atypical morphology, frequent CD2 expression and association with the bcr-3 type PML/RARA fusion transcripts. Early recognition of this rare entity is essential for timely and appropriate treatment.

Leukemic Pleural Effusion in Acute Promyelocytic Leukemia: A Case Report

In patients with acute myeloid leukemia (AML), pleural effusion may be attributed to various factors, including infection, hypoalbuminemia, and renal failure. However, leukemic infiltration of the pleural fluid is rarely reported and poorly understood. Extramedullary diseases have been reported with increasing frequency as the survival rates of patients with AML have increased. However, the reported prognostic effects of leukemic pleural effusion in patients with AML range from none to a worse prognosis. Here, we report a case of acute promyelocytic leukemia (APL) in a patient exhibiting leukemic pleural effusion with fluorescence in situ hybridization (FISH) results indicating the presence of the PML-RARA fusion gene. A 52-year-old man presented with pancytopenia, dyspnea, and fever. He had a medical history of hypertension, end-stage renal disease, and hepatitis B virus-related liver cirrhosis. A peripheral blood smear revealed the presence of multiple abnormally hypergranular promyelocytes. White blood cell differential counts were not performed due to severe pancytopenia. A bone marrow examination, immunophenotyping analysis, and cytogenetic and molecular studies revealed APL. The patient was treated with all-trans retinoic acid immediately after abnormal promyelocytes were observed in the peripheral blood smear, but induction chemotherapy was delayed because of his poor condition. His persistent dyspnea and abdominal discomfort led to a thoracentesis and the observation of abnormal promyelocytes that were positive for PML-RARA fusion gene by FISH. To our knowledge, this is the first report of leukemic pleural infiltration with PML-RARA fusion gene-positivity via FISH.

A Case of Acute Promyelocytic Leukemia with Co-existence of BCR-ABL1 and PML-RARA Rearrangements Detected by PCR

Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML) characterized by PML-RARA fusion and specific morphology. The BCR-ABL1 rearrangement is mainly observed in patients with chronic myeloid leukiemia (CML). However, it is also found in patients with acute lymphoblastic leukemia (ALL) and in a few patients with AML. However, it is very rarely observed in patients with APL. Here, we report a case of APL with t(15;17) and co-existence of PML-RARA and BCR-ABL1. Further study with more cases is warranted to find the right treatment and prognostic significance.

Clinical study of children with acute promyelocytic leukemia treated with arsenic trioxide with positive PML -RARa fusion gene / 中华实用儿科临床杂志

Objective To evaluate the efficacy of different treatment regimens for children with acute promye-locytic leukemia (APL)with positive PML -RARa fusion gene.Methods Thirty -two newly diagnosed APL patients were included in this study,treated either with all -trans -retinoic acid (ATRA)and chemotherapy (CT)(group A) or with ATRA and arsenic trioxide (ATO)(group B).Clinical situation and clinical efficacy were analyzed in patients in different groups.They were also separated into low risk group,intermediate risk group and high risk group according to different risk criteria.Clinical characteristics,complete remission,long -time survival and urine arsenic concentra-tion were analyzed and compared.Results (1 )Fourteen of 1 5 patients (93.3%)in group A achieved hematological complete remission (HCR)with a median time of 38 days (28 -63 days).Sixteen of 1 7 patients (94.1 %)in group B achieved HCR with a median time of 29 days (1 0 -42 days),which was significantly shorter than group A,and there was a significant difference between 2 groups(t =3.53,P =0.002).(2)The 5 -year event -free survival (EFS)of group A and group B was (60.0 ±1 2.6)% and (81 .9 ±9.5)%,respectively;the 5 -year EFS of group B was almost 20% higher than group A;while there was no significant difference between the 2 groups(χ2 =1 .1 5,P =0.28).The 5 -year overall survival (OS)of group A and group B was (72.2 ±1 1 .9)% and (94.1 ±5.7)%,respectively,the 5 -year OS of group B was almost 20% higher than group A;while there was no significant difference between the 2 groups(χ2 =2.88,P =0.1 6).(3)The 5 -year EFS of low plus intermediate group and high risk group patients was (74.0 ±1 0.1 )% and (64.8 ±1 4.3)%,the 5 -year EFS of low plus intermediate group was almost 1 0% higher than high risk group,but there was no significant difference between the 2 groups(χ2 =0.1 4,P =0.71 ).The 5 -year OS of low plus intermediate group and high risk group patients was (84.7 ±8.1 )% and (71 .3 ±1 4.1 )%,the 5 -year OS of low plus intermediate group was almost 1 0% higher than high risk group,while there was no significant difference be-tween the 2 groups(χ2 =0.36,P =0.55).(4)ATO related side effects were mild,including abnormal liver tests and e-lectrocardiogram,but were invertible after supportive therapy.At the end of each chemotherapy course,the urine arsenic concentration remained low and no chronic arsenic toxicity or second malignancies were found during the follow -up period.Conclusions The ATRA plus ATO regimen is a promising and better treatment for childhood APL with positive PML -RARa fusion gene compared with conventional chemotherapy.It was necessary to take risk stratification in APL patients.

Clinical analysis of 43 childhood APL with APL2008 / 重庆医学

Objective To evaluate the treatment of current status and prognosis in childhood APL with APL2008 ,which was administrated since 2008 in our center .Methods A total of 43 children with newly diagnosed APL between 2008 to 2014 were studied retrospectively .Treatment options and current status were summarized from 28 patients who received APL2008 therapy . Results Studied 43 patients were at median age of 8 years and 4 months ,with 28 boys and 15 girls .The main clinical manifestations were infection ,anemia ,bleeding ,fever ,hepatomegaly ,splenomegaly and lymphadenopathy .The proportions of low ,intermediate and high risk groups were 27 .9% ,48 .8% and 23 .3% ,respectively .Eleven cases could be diagnosed as DIC .Bone marrow morphology showed abnormal elevation of promyelocyte .37 patients had distinctive immunophenotype such as frequent expression of CD33 , CD117 and MPO .PML/RARαfusion gene positive rate was 100% in 43 children and cytogenetic analysis were positive in 37 cases , of which specific genetic lesion in APL cells with t (15 ;17)(q22 ;q12) was found in 28 cases ,and karyotypes was found in 9 cases as infrequent chromosomal abnormalities .In 43 patients ,4 cases were early dead from intracranial hemorrhage at early stage ,and 11 cases were given up early .There were only 2 cases dead ,2 cases relapsed and 1 case lost among 28 APL children ,which enabled ef‐ficacy analysis possible .96 .4% of these 28 cases achieved HCR .The 2 year Kaplan Meier estimates of OS and EFS were 85 .9% ± 7 .6% and 80 .4% ± 8 .8% .But OS and EFS would be 94 .7% ± 5 .1% and 88 .9% ± 7 .4% if 3 patients who had non standard treat‐ment were excluded .Conclusion Childhood APL were characterized by anemia ,bleeding ,fever and infiltration .APL′s coincidence rate between PML/RARa fusion gene and morphology ,immunology and cytogenetics were 95 .3% ,90 .2% and 86 .5% ,respective‐ly .APL2008 significantly improved the prognosis of APL .

Current routine practice and clinico-pathological characteristics associated with acute promyelocytic leukemia in Korea

BACKGROUND: Acute promyelocytic leukemia (APL) can be life threatening, necessitating emergency therapy with prompt diagnosis by morphologic findings, immunophenotyping, cytogenetic analysis, or molecular studies. This study aimed to assess the current routine practices in APL and the clinico-pathologic features of APL. METHODS: We reviewed the medical records of 48 Korean patients (25 men, 23 women; median age, 51 (20-80) years) diagnosed with APL in 5 university hospitals between March 2007 and February 2012. RESULTS: The WBC count at diagnosis and platelet count varied from 0.4 to 81.0 (median 2.0)x10(9)/L and 2.7 to 124.0 (median 54.5)x10(9)/L, respectively. The median values for prothrombin time and activated partial thromboplastin time were 14.7 (11.3-44.1) s and 29 (24-62) s, respectively. All but 2 patients (96%) showed a fibrin/fibrinogen degradation product value of >20 microg/mL. The D-dimer median value was 5,000 (686-55,630) ng/mL. The t(15;17)(q22;q12 and PML-RARA fusion was found in all patients by chromosome analysis and/or multiplex reverse transcriptase-polymerase chain reaction (RT-PCR), with turnaround times of 8 (2-19) d and 7 (2-13) d, respectively. All patients received induction chemotherapy: all-trans retinoic acid (ATRA) alone (N=11, 26%), ATRA+idarubicin (N=25, 58%), ATRA+cytarabine (N=3, 7%), ATRA+idarubicin+cytarabine (N=4, 9%). CONCLUSION: Since APL is a medical emergency and an accurate diagnosis is a prerequisite for prompt treatment, laboratory support to implement faster diagnostic tools to confirm the presence of PML-RARA is required.

Current routine practice and clinico-pathological characteristics associated with acute promyelocytic leukemia in Korea

BACKGROUND: Acute promyelocytic leukemia (APL) can be life threatening, necessitating emergency therapy with prompt diagnosis by morphologic findings, immunophenotyping, cytogenetic analysis, or molecular studies. This study aimed to assess the current routine practices in APL and the clinico-pathologic features of APL. METHODS: We reviewed the medical records of 48 Korean patients (25 men, 23 women; median age, 51 (20-80) years) diagnosed with APL in 5 university hospitals between March 2007 and February 2012. RESULTS: The WBC count at diagnosis and platelet count varied from 0.4 to 81.0 (median 2.0)x10(9)/L and 2.7 to 124.0 (median 54.5)x10(9)/L, respectively. The median values for prothrombin time and activated partial thromboplastin time were 14.7 (11.3-44.1) s and 29 (24-62) s, respectively. All but 2 patients (96%) showed a fibrin/fibrinogen degradation product value of >20 microg/mL. The D-dimer median value was 5,000 (686-55,630) ng/mL. The t(15;17)(q22;q12 and PML-RARA fusion was found in all patients by chromosome analysis and/or multiplex reverse transcriptase-polymerase chain reaction (RT-PCR), with turnaround times of 8 (2-19) d and 7 (2-13) d, respectively. All patients received induction chemotherapy: all-trans retinoic acid (ATRA) alone (N=11, 26%), ATRA+idarubicin (N=25, 58%), ATRA+cytarabine (N=3, 7%), ATRA+idarubicin+cytarabine (N=4, 9%). CONCLUSION: Since APL is a medical emergency and an accurate diagnosis is a prerequisite for prompt treatment, laboratory support to implement faster diagnostic tools to confirm the presence of PML-RARA is required.

Clinical study of acute promyelocytic leukemia with expression of BCR 3 isoform of PML-RARa fusion gene / 重庆医学

Objective To assess the efficacy of combination therapy with all-trans-retinoic acid (ATRA ) and arsenic trioxide (ATO) in treating patients with acute promyelocytic leukemia (APL) .Methods A retrospective study was conducted to evaluate the efficacy of combining ATO with ATRA based induction therapy ,followed by 3 courses of consolidation chemotherapy and 2-year sequential ATO/ATRA maintenance therapy in newly diagnosed APL ,and the efficacy between high risk group and low/inter-mediate risk group ,also between different PML-RARa isoform sub-group were compared .Results In high risk group and low/in-termediate risk group ,the complete remission(CR)rates were 70 .0% and 96 .9% (P=0 .04) ,respectively ;the 3 years overall sur-vival rates(OS) and disease free survival rates (DFS) were(70 .0 ± 14 .5)% ,(96 .9 ± 3 .1)% ,P= 0 .01 and(66 .7% ± 19 .2)% , (93 .8 ± 6 .1)% ,P=0 .08 ,respectively .In BCR1 group and BCR3 group ,the CR were 78 .6% and 95 .6% (P=0 .14) ,respectively ;the rates of 3 years OS and DFS were(95 .7 ± 4 .3)% ,(78 .6 ± 11 .0)% ,P=0 .18 ,and(92 .9 ± 6 .9)% ,(87 .5 ± 11 .7)% ,P=0 .24 , respectively .Conclusion The results indicate that ATO based first-line protocol is highly effective for treatment of newly diagnosed APL ,especially for the PML-RARa BCR3 isoform APL .

Characterization of cryptic rearrangements, deletion, complex variants of PML, RARA in acute promyelocytic leukemia.

Acute promyelocytic leukemia (APL) is characterized by a reciprocal translocation t(15;17)(q22;q21) leading to the disruption of Promyelocytic leukemia (PML) and Retionic Acid Receptor Alpha (RARA) followed by reciprocal PML–RARA fusion in 90% of the cases. Fluorescence in situ hybridization (FISH) has overcome the hurdles of unavailability of abnormal and/or lack of metaphase cells, and detection of cryptic, submicroscopic rearrangements. In the present study, besides diagnostic approach we sought to analyze these cases for identification and characterization of cryptic rearrangements, deletion variants and unknown RARA translocation variants by application of D-FISH and RARA break-apart probe strategy on interphase and metaphase cells in a large series of 200 cases of APL. Forty cases (20%) had atypical PML–RARA and/or RARA variants. D-FISH with PML/RARA probe helped identification of RARA insertion to PML. By application of D-FISH on metaphase cells, we documented that translocation of 15 to 17 leads to 17q deletion which results in loss of reciprocal fusion and/or residual RARA on der(17). Among the complex variants of t(15;17), PML–RARA fusion followed by residual RARA insertion closed to PML–RARA on der(15) was unique and unusual. FISH with break-apart RARA probe on metaphase cells was found to be a very efficient strategy to detect unknown RARA variant translocations like t(11;17)(q23;q21), t(11;17)(q13;q21) and t(2;17)(p21;q21). These findings proved that D-FISH and break-apart probe strategy has potential to detect primary as well as secondary additional aberrations of PML, RARA and other additional loci. The long-term clinical follow-up is essential to evaluate the clinical importance of these findings.

Recent advances in the diagnosis and management of childhood acute promyelocytic leukemia / 소아과

Since the successful introduction of all-trans-retinoic acid (ATRA) and its combination with anthracycline-containing chemotherapy, the prognosis for acute promyelocytic leukemia (APL) has markedly improved. With ATRA and anthracycline-based-chemotherapy, the complete remission rate is greater than 90%, and the long-term survival rate is 70-89%. Moreover, arsenic trioxide (ATO), which was introduced for APL treatment in 1994, resulted in excellent remission rates in relapsed patients with APL, and more recently, several clinical studies have been designed to explore its role in initial therapy either alone or in combination with ATRA. APL is a rare disease in children and is frequently associated with hyperleukocytosis, which is a marker for higher risk of relapse and an increased incidence of microgranular morphology. The frequency of occurrence of the promyelocytic leukemia/retinoic acid receptor-alpha (PML/RARalpha) isoforms bcr 2 and bcr 3 is higher in children than in adults. Although recent clinical studies have reported comparable long-term survival rates in patients with APL, therapy for APL in children is challenging because of the risk of early death and the potential long-term cardiac toxicity resulting from the need to use high doses of anthracyclines. Additional prospective, randomized, large clinical trials are needed to address several issues in pediatric APL and to possibly minimize or eliminate the need for chemotherapy by combining ATRA and ATO. In this review article, we discuss the molecular pathogenesis, diagnostic progress, and most recent therapeutic advances in the treatment of children with APL.

Detección de anticuerpos contra la proteína de fusión PML/RARa en la leucemia promielocítica / Detection of antibodies to PM/RARa fusion protein in promyelocytic leukemia

La leucemia promielocítica (LPM) está asociada con características genéticas únicas que incluyen la translocación recíproca t(15;17)(q22;q12) con la formación del complejo PML-RARa, el cual representa más del 95 por ciento de las proteínas de fusión en la LPM y resulta una diana potencial de la respuesta inmune. Los tratamientos actuales conocidos por terapias de diferenciación combinan el ácido trans retinoico (ATRA) y las antraciclinas, así como el trióxido de arsénico; resultan en una sobrevida a largo plazo y la cura potencial aproximadamente entre el 70 y 80 por ciento de los pacientes. En estudios realizados en ratones con LPM inmunizados con una vacuna de ADN elaborada mediante la fusión del oncogen PML-RARa al fragmento C de la toxina tetánica como adyuvante, conjuntamente con ATRA, se produjeron títulos elevados de anticuerpos. Se logró una sobrevida significativa, entre 120-300 días, comparada con la de ratones a los que se administró placebo. En nuestro trabajo se detectó la presencia de anticuerpos contra la proteína de fusión PML-RARa en diferentes fases del tratamiento, lo que indica la capacidad de respuesta de estos pacientes frente al antígeno tumoral. Los anticuerpos anti PML-RARa se detectaron en aquellos pacientes sin tratar y en fase de inducción, no así en la consolidación y mantenimiento, de ahí su posible utilidad como marcador de diferenciación celular a partir de la presencia o ausencia de la proteína de fusión en la célula leucémica.

Promyelocytic leukemia (PML) is associated with unique genetic features including the t reciprocal translocation (15; 17) (q22; q22) with PML-RARa, which accounted for more than 95 percent of fusion protein in PML and is a potential target of immune response. The current treatments known as differentiation therapies combine the trans-retinoic acid (TRA) and the anthracyclines, as well as the trioxide arsenic (As(2)0(3)); become in a long-term survival and the potential cure in about the 70 to 80 percent of patients. In studies conducted in LPM-mice immunized with a DNA vaccine made the PML-RARa oncogene fusion to C fragment of tetanus toxin as coadjuvant together with TRA were antibodies high titers. It was possible to achieve a significant survival among 120-130 days compared with that of placebo-mice. In our paper it was detected the presence of antibodies to PML-RARa fusion protein in different phases of treatment indicating the response to these patients to tumor antibody. The anti-PML-RARa were detected in those non-treated patients and in induction fusion, but not in consolidation and maintenance, thus its potential usefulness as cellular differentiation marker from presence or absence of fusion protein un leukemic cell.

Detection of PML/RARA Rearrangement by Reverse Transcriptase-PCR and Sequencing in a Case of Microgranular Acute Promyelocytic Leukemia Lacking t(15;17) on Karyotype and FISH / 대한진단검사의학회지

We report a case of morphologically microgranular acute promyelocytic leukemia with PML/RARA fusion transcripts demonstrated by reverse transcriptase-PCR and cDNA sequencing, and no PML/RARA fusion detected by karyotype and FISH analyses. Karyotype was 47,XX,+8[19]/46,XX[1]. Although the newer FISH probes provide more accurate detections of t(15;17), it would be necessary to perform other molecular tests to further identify the masked PML/RARA fusions.

Morphological characteristics of leukemia cells in acute myeloblastic leukemia with t(8;21)(q22;q22): possible predictability of t(8;21).

The laboratory systems for chromosomal analysis or the detection of fusion genes are generally not available in Indonesia. Therefore, bone marrow (BM) morphological analysis should be developed and applied to get an accurate diagnosis. In this study the BM smears of eight (8) cases of acute myeloblastic leukemia (AML) which had already been known to have t(8;21)(q22;q22), were morphologically evaluated in order to find out the characteristics, which might be used to predict t(8;21)(q22;q22) or the presence of AML1-ETO(MTG8) fusion gene. All of the cases belonged to AML-M2. The morphological characteristics, indicative of t(8;21) were pink colored cytoplasm in mature neutrophil (75%), neutrophilic myelocytes or metamyelocytes without granules or with scarce granules (2.3%), eosinophilia (eosinophilic myelocytes and metamyelocytes) (above 5%), myelocytes with abundant granules 8.5%, and low percentage of type I blasts (below 10%). These characteristics were not observed in AML-M2 cases without t(8;21) or AML1-ETO(MTG8). The myelocytes with abundant granules have not been described so far, while other characteristics were in line with the findings of Nakamura et al (Leukemia 1997;11:651-55).

Novel PML-RARA Fusion Gene on Chromosome 17 in Acute Promyelocytic Leukemia with Normal Chromosome 15 and 17 / 대한혈액학회지

We describe a patient with acute promyelocytic leukemia (APL) with no detectable cytogenetic abnormality of either chromosomes 15 or 17 who nevertheless had juxtaposition of promyelocytic leukemia (PML) and retinoic acid receptor-alpha (RARA) and expressed a chimeric transcript. Conventional cytogenetics showed the 46, XX. The metaphase fluorescence in situ hybridization (FISH) with a 5' PML and 3' RARA probe showed a juxtaposed PML-RARA fusion signal on one chromosome 17 homologue, an RARA signals on the other chromosome 17 homologue, and one PML signal on each chromosome 15 homologue. Our patient is presently in remission and doing well after chemotherapy with idarubicin and all trans retinoic acid (ATRA) treatment. Our results show that APL patients with cytogenetically normal chromosome 15 and 17 may, nevertheless, have involvement of both PML and RARA genes and as the prognostic outcome in APL is associated with the presence of a PML-RARA fusion, it is necessary to perform RT-PCR or FISH to aid diagnosis.

Utility of RARa Fluorescence In Situ Hybridization for Follow-up in Acute Promyelocytic Leukemia: Comparison with PML/RARa Fluorescence In Situ Hybridization / 대한임상병리학회지

BACKGROUND: The most noted rearrangement identified in acute promyelocytic leukemia (APL) involves the PML and RARa genes, which results in the formation of the PML/RARa gene fusion. In the fluorescence in situ hybridization (FISH) for PML/RARa, the two signals may coincidentally overlap in normal nuclei. We investigated whether a new RARa rearrangement probe could discriminate the false-positive fusion signal of the PML/RARa translocation probe. METHODS: A total of 51 cases, which showed the results from 1% to the borderline level by PML/ RARa FISH, were re-tested with the RARa rearrangement probe. Also, we compared the RARa FISH with the PML/RARa FISH on 16 patients with newly diagnosed APL and performed the RARa FISH on 20 bone marrow specimens without hematologic malignancies in order to set up the cut-off value. RESULTS: The cut-off for the RARa FISH was determined as 1.02%. For patients with newly diagnosed APL, the PML/RARa FISH showed positive signals in 95.3+/-6.5% of the cells and RARa FISH showed positive signals in 97.0+/-7.0% (r=0.83). Of a total of 41 cases consisting of hematological disorders other than APL, five cases showed results equal to or greater than 5% with PML/RARa FISH and one case showed a positive result with RARa FISH. Of 10 follow-up APL cases, seven cases showed results equal to or greater than 5% with the PML/RARa FISH and four cases showed positive results with the RARa FISH. CONCLUSIONS: The cut-off value for the RARa FISH is 1.02% and we consider RARa FISH as the proper method for follow-up of APL.

Detection of Long and Short isoforms of PML-RARA mRNA by RT-PCR in Acute Promyelocytic Leukemia / 대한혈액학회지

BACKGROUND: Chromosomal translocation t (15 ; 17), the breakpoints of which are in the PML gene on chromosome 15 and RARA gene on chromosome 17, is specifically found in acute promyelocytic leukemia (APL). According to the site of breakpoint on PML gene, two major isoforms (Long or Short) of PML-RARA mRNA are produced. METHODS: To detect long (L) and short (S) isoforms, we extracted RNA and amplified PML-RARA mRNA by RT-PCR from leukemic cells of 20 cases of APL. We compared the result of cytogenetic study and the clinical response after chemotherapy or ATRA therapy for remission induction with the isoforms of PML-RARA mRNA. RESULTS: In 19 cases (94%) among 20 cases with APL, PML-RARA mRNA was positive, and negative in a case who showed only i (17q) without t (15;17). In 12 cases (63.2%), L isoform of PML-RARA mRNA was detected, and S isoform (36.8%) in 7 cases of APL. All the cases with t (15;17) were positive for PML-RARA mRNA. In a case of trisomy 8 without t (15;17), PML-RARA mRNA of L isoform was detected. There was no significant difference between L and S isoform in laboratory findings and clinical response after chemotherapy or ATRA treatment. Excluding 6 cases with death before or within 10 days of ATRA treatment or chemotherapy, among 13 patients of positive PML-RARA mRNA, 11 cases (84.6%) reached to complete remission, but a case of negative PML-RARA mRNAwas resistent to ATRA treatment. CONCLUSION: This study suggests that detection of PML-RARA mRNA with two major isofroms using RT-PCR is more sensitive to diagnose APL and to detect minimal residual disease than cytogenetic study and that further study with more cases may be substantiated the types of PML-RARA mRNA isoform as a prognostic marker.