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).

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Ginsenoside Rg3, a natural compound, has been reported to function as an anticancer agent for hepatoma carcinoma, while the mechanisms underlying the anticancer effects are not clear. Therefore, the objective of our study was to explore the impact of RG3 on cell migration and invasion by regulating the lncRNA HOX antisense intergenic (HOTAIR) expression involving PI3K/ AKT signaling pathway. qRT-PCR was utilized to measure the mRNA expression of HOTAIR. Furthermore, HOTAIR overexpression plasmids were transfected to SMMC-7721 and SK-Hep-1 cells. Additionally, MTT assay was used to evaluate the proliferation of transfected cells. The scratch and transwell assays were used to determine the migration and invasion ability of the cell. The protein levels were determined with Western blot. lncRNA HOTAIR was overexpressed in SMMC-7721 and SK-Hep-1 cells. Ginsenoside-Rg3 reduced the level of lncRNA HOTAIR. Overexpressed lncRNA HOTAIR offset ginsenoside-Rg3 inhibited proliferation, migration and invasion of HCC cells. Furthermore, ginsenoside-Rg3 decreased the expression of p-AKT, p-PI3K, matrix metalloproteinase-2 (MMP2) and matrix metalloproteinase-9 (MMP9), which was reversed after the treatment of HOTAIR. LncRNA HOTAIR was overexpressed in SMMC-7721 cells. Ginsenoside-Rg3 could reduce the expression of lncRNA HOTAIR, resulting in the inhibited cell proliferation, migration and invasion. Furthermore, ginsenoside-Rg3 inhibited cell proliferation and invasion ability through the PI3k/AKT pathway. Thus, ginsenoside-Rg3 might be a potential and effective treatment for HCC.