A small molecule inhibitor of Mitf-E-box DNA binding and its depigmenting effect in melan-a cells.

BACKGROUND: Microphthalmia associated transcription factor (Mitf) is a key regulatory transcriptional factor of pigmentation-related genes including tyrosinase. Inhibition of tyrosinase transcription by blocking the binding of Mitf with its promoter E-box DNA can control the pigmentation. However, no such chemicals were reported so far. OBJECTIVE: To discover and evaluate the small molecule inhibitors of Mitf-E-box DNA. METHODS: Candidate chemicals were screened by virtual screening from pharmacophore data followed by Mitf E-box DNA protein chip. After selecting the chemical, its inhibitory activity on binding interaction between Mitf and E-box DNA, electrophoretic mobility shift assay (EMSA) was performed. To evaluate the depigmenting activity of Compound #17, cellular melanin assa, and Western blot were performed in melan-a cells. RESULTS: Among 27 chemicals selected from a pharmacophore data by virtual screening, Compound #17 was screened, which showed the most potent inhibitory activity against Mitf-E-box DNA binding in protein chip. EMSA results confirmed the specific inhibition of Compound #17 on Mitf-E-box DNA binding. In melan-a cells, Compound #17 reduced tyrosinase expression and melanin synthesis (62.5% at 25 µM). CONCLUSIONS: The results show that Compound #17 is the first small molecule inhibitor of Mitf-E-box DNA binding with depigmenting activity.

Molecular detection of TEL-AML1 transcripts as a diagnostic tool and for monitoring of minimal residual disease in B-lineage childhood acute lymphoblastic leukemia.

The chromosomal translocation t(12;21) (p12;q22) which results in the TEL-AML1 fusion gene is the most frequent genetic rearrangement in childhood B-lineage acute lymphoblastic leukemia (ALL). The rearrangement in this locus, however, is only rarely observed by routine karyotypic analysis. We established a nested-reverse transcriptase-polymerase chain reaction (nested-RT-PCR) technique for the detection of the TEL-AML1 transcript, and used this to investigate the incidence of the rearrangement, and to characterize the disease present in TEL-AML1-positive B-lineage ALL patients. The TEL-AML1 fusion transcript was detected in nine of fourteen patients. These patients were relatively homogeneous in that they were young and had low presenting leukocyte counts, both features of which are associated with a favorable prognosis. Furthermore, we could detect the TEL-AML1 transcript in the peripheral blood of t(12;21)-positive patients and we used this to assess minimal residual disease (MRD) in patients during chemotherapy. The data demonstrate that nested-RT-PCR is a suitable tool for diagnosing t(12;21)-positive ALL, that these patients constitute a clinically distinct subgroup of ALL patients, and that the method could also be used to monitor MRD in these patients.