Fluorescence Quantitative PCR Detection of FLT3 Gene Expression in Leukemias and Its Clinical Implications.

Objective In order to study the clinical significance of the FLT3 expression level in AML patients.

Methods we analyzed the expression level of the FLT3 transcript quantitatively by real time fluorescence quantitative PCR amplification and investigated correlations with FLT3/ITD gene mutation in 69 de novo AML cases.

Results The mean of FLT3 transcripts in the 69 AML patients was 17240 copies/μgRNA(273~834805), which was significantly higher in AML cases than in healthy donors (p=0.017). The FLT3 expressions were not equally distributed among the FAB subtypes(P=0.0005). The leukocyte counts was significantly related to FLT3 expression (P=0.0001 and r=0.4494). There were noticeable deviation among karyotypes in the expression of FLT3. The expression of cases with t(15;17) was lower that that of cases with t(11q23) and complex karyotypes. There was no significant difference of FLT3 mRNA between patiens positive and negtive for CD34 (P=0.315). FLT3/ITD gene mutation was observed in 17 of total 69 cases with AML(24.6%). There was no significant difference of FLT3 mRNAamong FLT3/ITD positive and negtive patients (P=0.205) and there was no significant difference of CR rates in high-FLT3-expression and low-FLT3-expression groups after chemical theropy(P=0. 425). During the follow-up of 210 days(median day=124), there was no significant difference of the cumulative relapse rates between these two groups (P=0.631).

Conclusion The expression of FLT3 gene was significantly higher in patiens with AML than in healthy donors and had a positive correlation with peripheral white blood cells counts. There was statistic difference among various FABs and karyotypes. FLT3 mRNA level in AML patients had no correlation with the expression of CD34 and FLT3/ITD gene mutation. In the short-term follow-up, high expression of FLT3 had no influence on CR, CRR and OS of AML patients.