Pharmacodynamics of Akt drugs revealed by a kinase-modulated bioluminescent indicator
Related Articles
Targeting AKT as a promising strategy for SOX2-positive, chemoresistant osteosarcoma
Osteosarcoma (OS) is the most prevalent type of primary malignant bone cancer and currently lacks effective targeted treatments. Increasing evidence indicates that SOX2 overexpression is a primary driver of OS. By screening a small-molecule kinase inhibitor library, we identified AKT as a kinase essential for robust SOX2 expression in OS cells. AKT was found to be frequently overexpressed in OS and positively correlated with SOX2 protein levels. We demonstrated that AKT has no effect on SOX2 transcription but promotes SOX2 protein stability. Mechanistically, AKT binds to and phosphorylates SOX2 at T116, preventing SOX2 ubiquitination and proteasome-dependent degradation by ubiquitin E3 ligases UBR5 and STUB1. Moreover, we found that AKT-SOX2 axis is a significant modulator of cancer stemness and chemoresistance and that the combination of AKT inhibitor MK2206 and cisplatin resulted in a synergistic and potent inhibition of OS tumor growth in the PDX model. In conclusion, we identified a critical role for AKT in promoting SOX2 overexpression, tumor stemness, and chemoresistance in OS, and provided evidence that targeting AKT combined with chemotherapy may hold promise for treating refractory OS.
βIV spectrin abundancy, cellular distribution and sensitivity to AKT/GSK3 regulation in schizophrenia
Schizophrenia (SCZ) is a complex psychiatric disorder with unclear biological mechanisms. Spectrins, cytoskeletal proteins linked to neurodevelopmental disorders, are regulated by the AKT/GSK3 pathway, which is implicated in SCZ. However, the impact of SCZ-related dysregulation of this pathway on spectrin expression and distribution remains unexplored. Here, we show that βIV spectrin protein levels were reduced in neurons of the dorsolateral prefrontal cortex in SCZ postmortem samples compared to healthy control (HC) from the Human Brain Collection Core (HBCC). To investigate potential links between βIV spectrin and the AKT/GSK3 pathway, we analyzed the PsychEncode dataset, revealing elevated SPTBN4 and AKT2 mRNA levels with correlated gene transcription in both HCs and individuals with SCZ. Next, computational tools were employed to identify potential AKT and GSK3 phosphorylation sites on βIV spectrin, and two GSK3 sites were validated through in vitro assays. To assess whether βIV spectrin distribution and sensitivity to AKT/GSK3 are altered in SCZ, we used iPSC-derived neurons from two independent cohorts of patients with significantly increased familial genetic risk for the disorder. Alteration in βIV spectrin levels and sensitivity to AKT/GSK3 inhibitors were consistently observed across both cohorts. Importantly, a Random Forest classifier applied to βIV spectrin imaging achieved up to 98% accuracy in classifying cells by diagnosis in postmortem samples, and by diagnosis or diagnosis × perturbation in iPSC samples. These findings reveal altered βIV spectrin levels and AKT/GSK3 sensitivity in SCZ, identifying βIV spectrin image-based endophenotypes as robust, generalizable predictive biomarkers of SCZ, with the potential for scalable clinical applications.
Anaerobic metabolism promotes breast cancer survival via Histone-3 Lysine-18 lactylation mediating PPARD axis
Histone lactylation plays a crucial role in cancer progression, but its impact on breast cancer (BC) tumorigenesis is still unclear. We utilized chromatin immunoprecipitation sequencing with H3K18la antibodies, transcriptomics of clinical BC samples, and proteomics and ATAC-seq analyses of in vivo tumors to identify the genes regulated by H3K18la and the transcription factor PPARD. qPCR and Western blot assays were used to detect expressions of molecules. We discovered that H3K18la levels were higher in BC tissues compared to adjacent non-cancerous tissues. H3K18la promoted the expression of PPARD, which in turn influenced the transcription of AKT, but not ILK. ATAC-seq analysis revealed that glycolysis in BC cells enhanced chromatin accessibility. Additionally, we confirmed that HDAC2 and HDAC3 act as “erasers” for H3 lysine lactylation. During the proteomics analysis, AKT-phosphorylation in the aerobic respiration inhibitor group exhibited an apparent disparity and activity. Our study demonstrated that changes in H3K18la in BC and its downstream transcription factor PPARD support cell survival under anaerobic glycolysis conditions. PPARD accelerated cancer proliferation by promoting the transcription and phosphorylation of AKT. This highlights the therapeutic potential of targeting the H3K18la/PPARD/AKT axis in breast cancer, providing new insights into epigenetic regulation and cancer metabolism (Trial registration: The study was approved by the Research Ethics Committee Shandong Provincial Third Hospital (KYLL-2023057; https://www.medicalresearch.org.cn/)).
SR-A3 suppresses AKT activation to protect against MAFLD by inhibiting XIAP-mediated PTEN degradation
Scavenger receptor class A member 3 (SR-A3) is implicated in metabolic diseases; however, the relationship between SR-A3 and metabolic dysfunction-associated fatty liver disease (MAFLD) has not been documented. Here, we show that hepatic SR-A3 expression is significantly reduced in human and animal models in the context of MAFLD. Genetic inhibition of SR-A3 in hamsters elicits hyperlipidemia, hyperglycemia, insulin resistance, and hepatic steatosis under chow-diet condition, yet escalates in diet-induced MAFLD. Mechanistically, SR-A3 ablation enhances E3 ligase XIAP-mediated proteasomal ubiquitination of PTEN, leading to AKT hyperactivation. By contrast, hepatic overexpression of human SR-A3 is sufficient to attenuate metabolic disorders in WT hamsters fed a high-fat-high-cholesterol diet and ob/ob mice via suppressing the XIAP/PTEN/AKT axis. In parallel, pharmacological intervention by PTEN agonist oroxin B or lipid lowering agent ezetimibe differentially corrects MAFLD in hamsters.
FBXO22 promotes HCC angiogenesis and metastasis via RPS5/AKT/HIF-1α/VEGF-A signaling axis
The gene F-box only protein 22 (FBXO22) has been discovered to promote the development of liver cancer tumors. Nevertheless, there remains considerable ambiguity regarding the involvement of FBXO22 in the processes of angiogenesis and metastasis in hepatocellular carcinoma (HCC). Our study has confirmed a significant upregulation of FBXO22 expression in both HCC samples and cellular models. The increased level of FBXO22 correlates strongly with the number of tumors, presence of vascular invasion, and poor prognosis. Experimental investigations have shown that FBXO22 significantly enhances angiogenesis and metastasis of HCC both in vitro and in vivo. Mechanistically, FBXO22 interacts with and ubiquitinates 40S ribosomal protein S5 (RPS5) on Lys85, thereby promoting its K48-linked ubiquitin-mediated degradation in the cytoplasm. Following a decrease in the expression of RPS5, activation of downstream PI3K/AKT signaling pathway occurs, leading to elevated levels of HIF-1α and vascular endothelial growth factor A (VEGF-A). Our study has shown that FBXO22 facilitates HCC angiogenesis and metastasis via the RPS5/AKT/HIF-1α/VEGF-A signaling axis. Notably, inhibition of FBXO22 enhances the efficacy of Lenvatinib both in vitro and in vivo. Therefore, FBXO22 may present itself as a potential target for therapeutic intervention in the treatment of HCC.
Responses