Dynamic Phosphoproteomics Uncovers Signaling Pathways Modulated by Anti-oncogenic Sphingolipid Analogs

Abstract

The anti-neoplastic sphingolipid analog SH-BC-893 starves cancer cells to death by down-regulating cell surface nutrient transporters and blocking lysosomal trafficking events. However, the actual mechanism of action giving rise to these phenotypes remains unclear. Here, dynamic phosphoproteomics was used to further understand how the activity of PP2A is affected following cell treatment with SH-BC-893. These analyses combined with functional assays identified the differential regulation of Akt and Gsk3b by SH-BC-893 and C2-ceramide as responsible for the vacuolation of cells by SH-BC-893 but not C2-ceramide.

Dynamic Transcriptomic and Phosphoproteomic Analysis During Cell Wall Stress in Aspergillus nidulans

“…Because of recent advancements in mass spectrometry technologies, there has been a shift from static -omic studies to dynamic studies ( 33 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ). However, comparison of these dynamic studies reveals significant differences in experimental design as well as data processing and analysis, such that no clear best-practice currently exists.…”

Phosphorylation Time‐Course Study of the Response during Adenovirus Type 2 Infection

“…These values are in good agreement with recent publications where Pearson's correlation coefficients of 0.68 and 0.75 were observed using SILAC or label‐free approaches. [ 33,34 ] When phosphorylated sites with opposite regulation profiles between the two biological replicates were removed from the analyses, the Pearson correlation r values dramatically improved (0.85, 0.86, 0.89, 0.92, and 0.92 at 2, 6, 12, 24, and 36 hpi, respectively). The percentage of phosphorylated sites not passing this criterion at early time points (30.6–36.5%) was higher than the number of phosphorylated sites removed at late time points (18.8–20.0%) (Table S1, Supporting Information).…”

Drug‐like sphingolipid SH‐BC‐893 opposes ceramide‐induced mitochondrial fission and corrects diet‐induced obesity

“…Many PP2A agonists inactivate AKT (Gutierrez et al , 2014 ; Suman et al , 2016 ; Tohmé et al , 2019 ; Tsuji et al , 2021 ) which makes them ill‐suited for use as obesity therapies as they would cause insulin resistance. SH‐BC‐893 does not reduce AKT phosphorylation (Kubiniok et al , 2019 ), most likely because it activates PP2A through a different mechanism than other agonists. Given that PP2A activation will have multiple downstream effects apart from alterations in endolysosomal trafficking, additional studies will be required to determine the extent to which mitochondria‐independent actions contribute to SH‐BC‐893’s anti‐obesogenic effects.…”

“…As tumor cell migration requires trafficking of mitochondria to the leading edge and mitochondrial transport depends on fission (Senft & Ronai, 2016 ), SH‐BC‐893 might additionally subvert cancer metastasis by blocking mitochondrial fission. Obesity itself promotes cancer through multiple mechanisms (Park et al , 2014 ; Ringel et al , 2020 ), and thus, SH‐BC‐893’s ability to reduce caloric intake (Fig 6A and B ) and adiposity (Fig 6H ) may synergize with its direct, cell‐autonomous effects on cancer cells (Chen et al , 2016 ; Kim et al , 2016 ; Finicle et al , 2018 ; Kubiniok et al , 2019 ). The growth of many tumors is spurred by insulin (Gallagher & LeRoith, 2020 ), and resolution of hyperinsulinemia by SH‐BC‐893 (Fig 7H and I ) could also limit tumor growth.…”