Proximity Labeling,
Quantitative Proteomics, and Biochemical
Studies Revealed the Molecular Mechanism for the Inhibitory Effect
of Indisulam on the Proliferation of Gastric Cancer Cells
posted on 2021-08-23, 05:04authored byJiaqi Lu, Honglv Jiang, Dan Li, Tao Chen, Yuhong Wang, Zhongjian Pu, Guoqiang Xu
Indisulam
exhibits antitumor activity against several cancer cells.
Although the DCAF15-indisulam-RBM39 axis has been well documented
in the inhibition of cancer cell growth, it is unknown whether RBM39
degradation alone is the mechanism of action of indisulam. Here, we
verified the inhibitory effect of indisulam on the proliferation of
gastric cancer cells and its dependence on DCAF15. Proximity-dependent
biotin labeling with TurboID and quantitative proteomics revealed
that indisulam indeed promoted the interaction between DCAF15 and
RBM39. Immunoblotting and immunofluorescence also revealed that indisulam
promoted the ubiquitin-mediated RBM39 degradation and RBM39 colocalized
with DCAF15 in the nucleus. DCAF15 knockdown almost completely abolished
the indisulam-mediated RBM39 reduction. Further knockdown of RBM39 eliminated the effect of DCAF15 on
the proliferation of gastric cancer cells upon indisulam treatment.
Immunoblotting of gastric tumor tissues confirmed the downregulation
of RBM39 by indisulam. Database analysis unveiled that RBM39 was highly expressed in gastric cancer tissues and its high expression
significantly shortened the survival time of gastric cancer patients.
Taken together, we demonstrated that indisulam enhanced RBM39 ubiquitination
and degradation by promoting its interaction with DCAF15, thus inhibiting
the proliferation of gastric cancer cells. This work may provide valuable
information for drug discovery through proteolysis targeting chimeras.
MS data were deposited in ProteomeXchange (Dataset identifier: PXD024168).