FLT3/ITD associated with an immature immunophenotype in PML-RARα leukemia

  • Mariko Takenokuchi | tmariko@himeji-du.ac.jp Faculty of Pharmacological Sciences, Himeji Dokkyo University, Himeji, Hyogo, Japan.
  • Seiji Kawano Department of Clinical Laboratory, Kobe University Hospital, Kobe, Hyogo, Japan.
  • Yuji Nakamachi Department of Clinical Laboratory, Kobe University Hospital, Kobe, Hyogo, Japan.
  • Yasuyuki Sakota Department of Clinical Laboratory, Kobe University Hospital, Kobe, Hyogo, Japan.
  • Meilani Syampurnawati Department of Internal Medicine, Faculty of Medicine, Gadjah Mada University, Dr Sardjito Hospital, Jalan Kesehatan, Yogyakarta, Indonesia.
  • Katsuyasu Saigo Faculty of Pharmacological Sciences, Himeji Dokkyo University, Himeji, Hyogo, Japan.
  • Eiji Tatsumi Department of Nutrition and Health, Sagami Women’s University, Sagami, Kanagawa, Japan.
  • Shunichi Kumagai Department of Clinical Pathology and Immunology, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan.

Abstract

Acute promyelocytic leukemia (APL) is characterized by the specific PML-RARa fusion gene resulting from translocation t(15;17) (q22;q12). Internal tandem duplication (ITD) of the FLT3 gene has been observed in approximately 35% of APLs, and large-scale studies have identified the presence of ITD as an adverse prognostic factor for acute myeloblastic leukemia (AML) patients. Aberrant expressions of surface antigens, such as CD2, CD34, and CD56, have been found in APL, but the implications of this are not well understood. We investigated the incidence of the FLT3/ITD mutation and FLT3/D835 (I836) point mutation in 25 APL patients. Incidence ratios of FLT3/ITD, D835 (I836), and both FLT3/ITD and D835 (I836) were 36%, 36% and 8%, respectively. FLT3/ITD+ cases showed a predominance of the bcr3 isoform (P=0.008) and M3v morphology (P<0.001). We found that all FLT3/ITD+ cases expressed CD2 (9 of 9) more frequently than that of FLT3/ITD- (1 of 16) (P<0.001), while only one of the CD2+ cases (1 of 10, 10%) did not harbor FLT3/ITD, and all CD2+CD34+ cases (5 of 5, 100%) harbored FLT3/ITD. In addition, quantitative polymerase chain reaction analysis showed that FLT3 mRNA was more abundantly expressed in FLT3/ITD+ than that in FLT3/ITD- (P=0.025), while there was no difference between D835(I836)+ and D835(I836)- with regards to aberrant surface-antigen expression, expression levels of FLT3 mRNA, M3v morphology, and the bcr3 isoform of PML-RARa mRNA. This study demonstrates that the presence of FLT3/ITD, but not D835 (I836), is closely related to aberrant CD2 expression and high expression levels of FLT3 mRNA. Our findings also suggest that FLT3/ITD as a secondary genetic event may block differentiation at the immature stage of APL.

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Published
2012-10-16
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Original Articles
Keywords:
FLT3/ITD, FLT3/ D835, CD2, immature phenotype
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How to Cite
Takenokuchi, M., Kawano, S., Nakamachi, Y., Sakota, Y., Syampurnawati, M., Saigo, K., Tatsumi, E., & Kumagai, S. (2012). FLT3/ITD associated with an immature immunophenotype in PML-RARα leukemia. Hematology Reports, 4(4), e22. https://doi.org/10.4081/hr.2012.e22