CBAP modulates Akt-dependent TSC2 phosphorylation to promote Rheb-mTORC1 signaling and growth of T-cell acute lymphoblastic leukemia

Insights into diosgenin against inflammatory bowel disease as functional food based on network pharmacology and molecular docking

Inflammatory bowel disease (IBD) is a growing global health problem. IBD is commonly prevalent in Europe and America and the incidence rate in Asia is on the rise due to altered dietary structure. Diosgenin is a natural steroidal saponin derived from Dioscorea plants. Diosgenin is the main active ingredient of some Chinese medicines which are mainly used to treat coronary heart disease, angina and hyperlipidemia. Recently, growing evidence has exhibited a crucial role of diosgenin and dioscin in alleviating IBD in multiple ways. However, the precise mechanism of diosgenin against IBD needs further exploration. In this study, network pharmacological and systematic bioinformatic analyses were performed to investigate the diosgenin's targets against IBD. 71 targets such as SRC, TNF and STAT3 were identified as overlapped genes between diosgenin and IBD. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis exhibited their involvement in the tyrosine kinase signaling pathway and its membrane receptors. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance and its downstream Ras-MAPK pathway and PI3K-Akt pathway might become the mechanism of diosgenin against IBD. In addition, molecular docking analysis showed that diosgenin has the massive potential of direct binding to tyrosine kinase and its receptors such as SRC, EGFR, FGFR1 and VEGFR. The results above collectively provided evidence that diosgenin is a promising nutraceutical food against IBD.

CBAP regulates the function of Akt-associated TSC protein complexes to modulate mTORC1 signaling

The Akt-Rheb-mTORC1 pathway plays a crucial role in regulating cell growth, but the mechanisms underlying the activation of Rheb-mTORC1 by Akt remain unclear. In our previous study, we found that CBAP was highly expressed in human T-ALL cells and primary tumors, and its deficiency led to reduced phosphorylation of TSC2/S6K1 signaling proteins as well as impaired cell proliferation and leukemogenicity. We also demonstrated that CBAP was required for Akt-mediated TSC2 phosphorylation in vitro. In response to insulin, CBAP was also necessary for the phosphorylation of TSC2/S6K1 and the dissociation of TSC2 from the lysosomal membrane. Here we report that CBAP interacts with AKT and TSC2, and knockout of CBAP or serum starvation leads to an increase in TSC1 in the Akt/TSC2 immunoprecipitation complexes. Lysosomal-anchored CBAP was found to override serum starvation and promote S6K1 and 4EBP1 phosphorylation and c-Myc expression in a TSC2-dependent manner. Additionally, recombinant CBAP inhibited the GAP activity of TSC2 complexes in vitro, leading to increased Rheb-GTP loading, likely due to the competition between TSC1 and CBAP for binding to the HBD domain of TSC2. Overexpression of the N26 region of CBAP, which is crucial for binding to TSC2, resulted in a decrease in mTORC1 signaling and an increase in TSC1 association with the TSC2/AKT complex, ultimately leading to increased GAP activity toward Rheb and impaired cell proliferation. Thus, we propose that CBAP can modulate the stability of TSC1-TSC2 as well as promote the translocation of TSC1/TSC2 complexes away from lysosomes to regulate Rheb-mTORC1 signaling.

PI3K/AKT/mTOR signaling transduction pathway and targeted therapies in cancer

The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved signal transduction network in eukaryotic cells that promotes cell survival, cell growth, and cell cycle progression. Growth factor signalling to transcription factors in the PAM axis is highly regulated by multiple cross-interactions with several other signaling pathways, and dysregulation of signal transduction can predispose to cancer development. The PAM axis is the most frequently activated signaling pathway in human cancer and is often implicated in resistance to anticancer therapies. Dysfunction of components of this pathway such as hyperactivity of PI3K, loss of function of PTEN, and gain-of-function of AKT, are notorious drivers of treatment resistance and disease progression in cancer. In this review we highlight the major dysregulations in the PAM signaling pathway in cancer, and discuss the results of PI3K, AKT and mTOR inhibitors as monotherapy and in co-administation with other antineoplastic agents in clinical trials as a strategy for overcoming treatment resistance. Finally, the major mechanisms of resistance to PAM signaling targeted therapies, including PAM signaling in immunology and immunotherapies are also discussed.

The Molecular Biology of Prostate Cancer Stem Cells: From the Past to the Future

Prostate cancer (PCa) continues to rank as the second leading cause of cancer-related mortality in western countries, despite the golden treatment using androgen deprivation therapy (ADT) or anti-androgen therapy. With decades of research, scientists have gradually realized that the existence of prostate cancer stem cells (PCSCs) successfully explains tumor recurrence, metastasis and therapeutic failure of PCa. Theoretically, eradication of this small population may improve the efficacy of current therapeutic approaches and prolong PCa survival. However, several characteristics of PCSCs make their diminishment extremely challenging: inherent resistance to anti-androgen and chemotherapy treatment, over-activation of the survival pathway, adaptation to tumor micro-environments, escape from immune attack and being easier to metastasize. For this end, a better understanding of PCSC biology at the molecular level will definitely inspire us to develop PCSC targeted approaches. In this review, we comprehensively summarize signaling pathways responsible for homeostatic regulation of PCSCs and discuss how to eliminate these fractional cells in clinical practice. Overall, this study deeply pinpoints PCSC biology at the molecular level and provides us some research perspectives.

Overexpression of transmembrane protein 102 implicates poor prognosis and chemoresistance in epithelial ovarian carcinoma patients

Most ovarian cancer patients experience disease recurrence and chemotherapeutic resistance, and the underlying mechanisms are unclear. Identifying relevant pathways could reveal new therapeutic targets. Here we examined expression of transmembrane protein 102 (TMEM102), a biomarker of prognosis and chemoresistance, in epithelial ovarian cancer (EOC), and assessed its role in inhibiting tumor cell apoptosis. We performed qRT-PCR to investigate the association of TMEM102 expression with clinical outcomes in 226 EOC patients. We also conducted in vitro studies to explore possible mechanisms through which TMEM102 may influence chemoresistance, including the effects of downregulating TMEM102 expression with small interfering RNA. Serous and high-grade carcinomas expressed significantly higher TMEM102 than normal ovarian tissues. TMEM102 was also overexpressed in patients with advanced-stage disease and chemoresistance. Reduction of TMEM102 expression by small interfering RNA induced ovarian cancer cell apoptosis after cytotoxic treatment. TMEM102 overexpression enhanced chemoresistance via upregulation of heat shock proteins 27, 60, and 70; and survivin, resulting in decreased cytochrome c in the mitochondria and decreased caspase 9 expression. Our results indicate that TMEM102 overexpression may promote chemoresistance via inhibition of a mitochondria-associated apoptotic pathway.

Rare Association of Tuberous sclerosis with Acute Lymphoblastic Leukemia: Case Report with Review of Literature

Acute lymphoblastic leukemia (ALL) is the most common leukemia in children in which 85% of all cases are of B-cell ALL and approximately 15% cases are of T-cell ALL (T-ALL). Recent revolution in next-generation sequencing has uncovered many novel somatic mutations and rearrangements in ALL cells, which have prognostic and therapeutic implications, and it has also led to recognition of germline variants in the same genes with somatic mutations commonly associated with ALL. Apart from increasing the risk of developing ALL, germline variants may influence diagnostic testing, genetic counseling, and response to antileukemic treatment. This emphasizes importance of identification of new germline variants, or association of inherited syndromes with ALL or other malignancies. Down's syndrome, Shwachman's syndrome, Fanconi anemia, Bloom's syndrome, neurofibromatosis, and ataxia telangiectasia are well-recognized conditions associated with ALL. In this communication, we report a rare association of T-ALL with tuberous sclerosis (TS). This is the first reported case, showing association of T cell leukemia and TS with confirmatory genetic work-up.

T cell receptor (TCR) signaling in health and disease

Interaction of the T cell receptor (TCR) with an MHC-antigenic peptide complex results in changes at the molecular and cellular levels in T cells. The outside environmental cues are translated into various signal transduction pathways within the cell, which mediate the activation of various genes with the help of specific transcription factors. These signaling networks propagate with the help of various effector enzymes, such as kinases, phosphatases, and phospholipases. Integration of these disparate signal transduction pathways is done with the help of adaptor proteins that are non-enzymatic in function and that serve as a scaffold for various protein-protein interactions. This process aids in connecting the proximal to distal signaling pathways, thereby contributing to the full activation of T cells. This review provides a comprehensive snapshot of the various molecules involved in regulating T cell receptor signaling, covering both enzymes and adaptors, and will discuss their role in human disease.

Discovery of Novel Dual Extracellular Regulated Protein Kinases (ERK) and Phosphoinositide 3-Kinase (PI3K) Inhibitors as a Promising Strategy for Cancer Therapy

Concomitant inhibition of MAPK and PI3K signaling pathways has been recognized as a promising strategy for cancer therapy, which effectively overcomes the drug resistance of MAPK signaling pathway-related inhibitors. Herein, we report the scaffold-hopping generation of a series of 1H-pyrazolo[3,4-d]pyrimidine dual ERK/PI3K inhibitors. Compound 32d was the most promising candidate, with potent inhibitory activities against both ERK2 and PI3Kα which displays superior anti-proliferative profiles against HCT116 and HEC1B cancer cells. Meanwhile, compound 32d possessed acceptable pharmacokinetic profiles and showed more efficacious anti-tumor activity than GDDC-0980 and the corresponding drug combination (BVD-523 + GDDC-0980) in HCT-116 xenograft model, with a tumor growth inhibitory rate of 51% without causing observable toxic effects. All the results indicated that 32d was a highly effective anticancer compound and provided a promising basis for further optimization towards dual ERK/PI3K inhibitors.

Construction of a prognosis-predicting model based on autophagy-related genes for hepatocellular carcinoma (HCC) patients

Background: Autophagy, a highly conserved cellular catabolic process by which the eukaryotic cells deliver autophagosomes engulfing cellular proteins and organelles to lysosomes for degradation, is critical for maintaining cellular homeostasis in response to various signals and nutrient stresses. The dysregulation of autophagy has been noted in the pathogenesis of cancers. Our study aims to investigate the prognosis-predicting value of autophagy-related genes (ARG) in hepatocellular carcinoma (HCC).

Results: The signature was constructed based on eight ARGs, which stratified HCC patients into high- and low-risk groups in terms of overall survival (OS) (Hazard Ratio, HR=4.641, 95% Confidential Interval, CI, 3.365-5.917, P=0.000). The ARG signature is an independent prognostic indicator for HCC patients (HR = 1.286, 95% CI, 1.194-1.385; P < 0.001). The area under the receiver operating characteristic (ROC) curve (AUC) for 5-year survival is 0.765.

Conclusion: This study provides a potential prognostic signature for predicting the prognosis of HCC patients and molecular insights into the significance of autophagy in HCC.

Methods: Sixty-two differentially expressed ARGs and the clinical characteristics and basic information of the 369 enrolled HCC patients were retrieved from The Cancer Genome Atlas (TCGA) database. the Cox proportional hazard regression analysis was adopted to identify survival-related ARGs, based on which a prognosis predicting signature was constructed.

Melatonin enhances thrombopoiesis through ERK1/2 and Akt activation orchestrated by dual adaptor for phosphotyrosine and 3-phosphoinositides

Melatonin (MT), endogenously secreted by the pineal gland, is closely related to multiple biological processes; however, its effect on thrombopoiesis is still not well illustrated. Here, we demonstrate that MT administration can elevate peripheral platelet levels. Analysis of different stages in thrombopoiesis reveals that MT has the capacity to promote the expansion of CD34⁺ and CD41⁺ cells, and accelerate proplatelet formation (PPF) and platelet production. Furthermore, in vivo experiments show that MT has a potential therapeutic effect on radiation-induced thrombocytopenia. The underlying mechanism suggests that both extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt signaling are involved in the processes of thrombopoiesis facilitated by MT. Interestingly, in addition to the direct regulation of Akt signaling by its upstream phosphoinositide 3-kinase (PI3K), ERK1/2 signaling is also regulated by PI3K via its effector, dual adaptor for phosphotyrosine and 3-phosphoinositides (DAPP1), in megakaryocytes after MT treatment. Moreover, the expression level of DAPP1 during megakaryocyte differentiation is closely related to the activation of ERK1/2 and Akt at different stages of thrombopoiesis. In conclusion, our data suggest that MT treatment can promote thrombopoiesis, which is modulated by the DAPP1-orchestrated activation of ERK1/2 and Akt signaling.