OBJECTIVETo investigate the frequency of different variant of API2-MALT1 fusion gene in extranodal marginal zone B-cell lymphoma of mucosa-associated tissue(MALT1) lymphoma and the correlation between API2-MALT1 transcript and apoptosis of MALT lymphoma.

METHODSThe API2-MALT1 fusion transcripts were detected in 62 cases of MALT lymphoma by reverse transcription-polymeras chain reaction(RT-PCR) and Nested PCR. Five cases with reactive proliferation of lymph node were in use for negative control, and beta-actin was regarded as internal control; the apoptosis index, mRNA and protein of API2 were assayed in all samples by means of TUNEL, RT-PCR and immunohistochemistry respectively.

RESULTSAPI2-MALT1 transcript was detected in 28 of 62 cases with MALT lymphoma (45.16%). Two kinds of API2-MALT1 variants (A1446-M1123 and A1446-M814) were detected. Variant A1446-M1123 was detected more frequently as compared with A1446-M814. The frequency of API2-MALT1 transcript was lower in thyroid MALT lymphoma(1/12) but similar in pulmonary and gastrointestinal MALT lymphoma. In the group of API2-MALT1(+), the apoptosis index was higher and the API2 mRNA and protein were lower when compared against those in the group of API2MALT1(-). But no significant differences in the levels of apoptosis and API2 were observed between the group of A1446-M1123(+) and A1446-M814(+).

CONCLUSIONAPI2-MALT1 transcript displayed variable frequency in MALT lymphomas of different sites. A1446-M1123 was noted to be probably the main type of API2-MALT1 variant in MALT lymphoma of Chinese. API2-MALT1 transcript was confirmed to be associated with the levels of apoptosis and API2 of MALT lymphoma.