Relation between microsatellite instability and N-ras mutation and duration of disease free survival in patients with acute leukemia.

BACKGROUND

Microsatellite instability (MIN) appears to be a novel molecular mechanism in carcinogenesis and is believed to reflect multiple replication errors. The authors analyzed MIN in de novo acute leukemia and its association with expression of the human MSH3 (hMSH3) gene and point mutations of the N-ras gene. The relation between MIN and disease free survival also was examined.

METHODS

The authors studied 43 cases of de novo acute leukemia for MIN at 5 loci. They also examined expression of the hMSH3 gene using the reverse transcriptase-polymerase chain reaction method. DNA taken from 36 cases at diagnosis was examined for N-ras mutations. The Kaplan-Meier method was used to estimate patients' disease free survival.

RESULTS

MIN at 1 locus was found in 7 of the 43 cases (16%) (MIN positive [MIN+] group). There was no correlation between MIN+ and decreased hMSH3 gene expression. Four of the 7 MIN+ cases (57%) had a mutation of the N-ras gene compared with only 1 of the 29 MIN- cases (3%). A correlation between N-ras mutations and MIN was detected (P < 0.003). The MIN+ patients had a shorter disease free survival than the MIN- patients (P < 0.03).

CONCLUSIONS

MIN may be associated with N-ras mutation in some cases of de novo acute leukemia and influence the duration of disease free survival.