The miRNA expression signature of human MALT lymphoma

To identify key tumour supressor miRNAs involed in MALT lymphoma pathogenesis Gastric mucosa-associated lymphoid tissue lymphoma develops in the chronically inflamed mucosa of Helicobacter pylori-infected patients. MicroRNA expression profiling of human MALT lymphoma revealed a 10-fold down-regulation of miR-203, which resulted from promoter hypermethylation and coincided with the dysregulation of the miR-203 target ABL1. Demethylating treatment of lymphoma B-cells led to an increase in miR-203 expression and concomitant ABL1 down-regulation. The lentiviral delivery of miR-203, as well as treatment with various ABL inhibitors, prevented primary MALT lymphoma cell proliferation in vitro. Finally, the treatment of tumor-bearing mice with imatinib induced MALT lymphoma regression in vivo. Our results show that MALT lymphomagenesis is epigenetically induced by miR-203 promoter methylation and identify ABL1 as a novel target for the treatment of this malignancy. 5 human fresh frozen MALT lymphoma samples were analysed and 4 human tonsil tissue samples were used as the non-tumour control