The dual role of HLXB9 in leukemia.

BACKGROUND

The HLXB9 gene encodes a homeodomain containing transcription factor which has been implicated in the development of both solid and hematological malignancies. In leukemia it is one of the two fused genes, along with ETV6, in a recurrent translocation frequently observed in infant AML.

PROCEDURE

Here we investigate the role of epigenetic inactivation of the HLXB9 gene in leukemia. Quantitative DNA methylation analysis was performed using the COBRA assay, and qRT-PCR was used to assess the effects of methylation on expression in hematological cell lines and primary ALL samples.

RESULTS

Hypermethylation of the HLXB9 gene was found to be a frequent event in childhood ALL, occurring in 33% of cases. However, it was rarely or never observed in other types of leukemia, including AML, CML, and CLL, with the exception of adult ALL, in which 39% of cases were hypermethylated. Furthermore, hypermethylation of HLXB9 results in loss of expression in hematological cell lines and primary ALL samples.

CONCLUSION

These results suggest that HLXB9 may have a dual role in childhood leukemia, as an oncogene in infant AML but as a tumor suppressor in childhood ALL.