| Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK), an
oncogenic fusion protein carrying constitutively active tyrosine
kinase, is known to be central to the pathogenesis of ALK-positive
anaplastic large cell lymphoma (ALK ALCL). Here, it is reported
that silibinin, a non-toxic naturally-occurring compound,
potently suppressed NPM-ALK and eff ectively inhibited the
growth and soft agar colony formation of ALK ALCL cells. By
western blots, it was found that silibinin effi ciently suppressed
the phosphorylation/activation of NPM-ALK and its key
substrates/downstream mediators (including STAT3, MEK/ERK
and Akt) in a time- and dose-dependent manner. Correlating with
these observations, silibinin suppressed the expression of Bcl-2,
survivin and JunB, all of which are found to be upregulated by
NPM-ALK and pathogenetically important in ALK ALCL. Lastly,
silibinin augmented the chemosensitivity of ALK ALCL cells to
doxorubicin, particularly the small cell sub-set expressing the
transcriptional activity of Sox2, an embryonic stem cell marker.
To conclude, the fi ndings suggest that silibinin might be useful
in treating ALK ALCL. |