Gads (Grb2-related adaptor downstream of Shc) is required for BCR-ABL-mediated lymphoid leukemia

Potential predictive value of serum targeted metabolites and concurrently mutated genes for EGFR-TKI therapeutic efficacy in lung adenocarcinoma patients with EGFR sensitizing mutations

There is a discrepancy in the efficacy of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) treatment for advanced lung adenocarcinoma (LUAD) patients with EGFR sensitizing mutations (mEGFR). Molecular markers other than mEGFR remain to be investigated to better predict EGFR-TKI efficacy. Here, 49 LUAD patients with mEGFR (19 deletions or 21 L858R mutations) who received the first-generation EGFR-TKI icotinib therapy were included and stratified into 25 good-responders with a progression-free survival (PFS) longer than 11 months and 24 poor-responders with a PFS shorter than 11 months. We conducted targeted metabolomic detection and next-generation sequencing on serum and tissue samples, respectively. Subsequently, two metabolomic profiling-based discriminant models were constructed for icotinib efficacy prediction, 10 metabolites overlapped in both models ensured high credibility for distinguishing good- and poor-responders. Seven of the 10 metabolites displayed significant differences between the two groups, which belong to lipids including ceramides (Cers), lysophosphatidylcholines (LPCs), lysophosphatidylethanolamines (LPEs), sphingomyelins (SMs), and free fatty acids (FAs). Briefly, LPC 16:1, LPC 22:5-1, and LPE 18:2 decreased in poor-responders, while Cer 36:1-3, Cer 38:1-3, SM 36:1-2 and SM 42:2 increased in poor-responders. In parallel, we identified 6 co-mutated genes (ARID1A, ARID1B, BCR, FANCD2, PTCH1, and RBM10) which were significantly correlated with a shorter PFS. Additionally, 4 efficacy-related metabolites (Cer 36:1-3, Cer 38:1-3, SM 36:1-2, and LPC 16:1) showed significant differences between the mutant and wild-type of 4 efficacy-related genes (ARID1A, ARID1B, BCR, and RBM10). SM 36:1-2 elevated while LPC 16:1 decreased in ARID1A, BCR, and RBM10 mutant groups compared to the wild-type groups. Cer 36:1-3 increased in the ARID1A and BCR mutant groups, and Cer 38:1-3 only rose in the ARID1A mutant group. Furthermore, we observed a causal-mediator-network-based interrelation between the 4 concurrently mutated genes and the 4 metabolites related metabolic genes in glycerophospholipid metabolism and sphingolipid metabolism pathways. This study demonstrated that lipids metabolism and concurrently mutated genes with mEGFR were associated with the icotinib efficacy, which provides novel perspectives in classifying clinical responses of mEGFR LUAD patients and reveals the potential of non-invasive pretreatment serum metabolites in predicting EGFR-TKI efficacy.

[Mechanisms of recombinant adenovirus-mediated SD-HA fusion protein proliferation inhibition and induced apoptosis of K562 cells]

Objective: To investigate whether fusion protein SD-HA could regulate its downstream signaling molecule activity by competing with the phospho-BCR-ABL Y177 site, and its mechanisms to inhibit proliferation and induce apoptosis of K562 cells. Methods: Co-immunoprecipitation interaction technology analysis of fusion protein SD-HA functioned by potently binding to the phospho-BCR-ABL Y177 site, Ras, MAPK and Akt activities were observed in the Ad5F35-SD-HA-treated cells. Western blot analyses of SD-HA fusion protein on cell membrane receptor pathway to death cascade caspase-8, caspase-3 and PRAP were performed. Results: Exploration into the underlying mechanisms revealed that Ad5F35-SD-HA infection functioned by binding to the phospho-BCR-ABL Y177 site, which lead to a complex with Grb2. competitively disrupted the Grb2 SH2-phospho-BCR-ABL Y177 formation. The fusion protein SD-HA could reduce the activation of Ras and phosphorylation of MAPK (p-MAPK) and the expression level of p-ELK, inhibition of Ras-MAPK signaling pathway; SD-HA fusion protein could reduce p-Akt and Akt substrate p-GSK with inhibition of PI3K-Akt signaling pathway, thereby inhibiting the proliferation of K562 cells. Caspases-8-induced apoptosis signal could be activated by DED protein binding to DED domain of precursor caspases-8. Conclusions: The strategy of fusion protein SD-HA inhibiting-Y177 BCR-ABL and Grb2 binding could be used as a novel entry point for the treatment of chronic myeloid leukemia.

The chimeric ubiquitin ligase SH2-U-box inhibits the growth of imatinib-sensitive and resistant CML by targeting the native and T315I-mutant BCR-ABL

Chronic myeloid leukemia (CML) is characterized by constitutively active fusion protein tyrosine kinase BCR-ABL. Although the tyrosine kinase inhibitor (TKI) against BCR-ABL, imatinib, is the first-line therapy for CML, acquired resistance almost inevitably emerges. The underlying mechanism are point mutations within the BCR-ABL gene, among which T315I is notorious because it resists to almost all currently available inhibitors. Here we took use of a previously generated chimeric ubiquitin ligase, SH2-U-box, in which SH2 from the adaptor protein Grb2 acts as a binding domain for activated BCR-ABL, while U-box from CHIP functions as an E3 ubiquitin ligase domain, so as to target the ubiquitination and degradation of both native and T315I-mutant BCR-ABL. As such, SH2-U-box significantly inhibited proliferation and induced apoptosis in CML cells harboring either the wild-type or T315I-mutant BCR-ABL (K562 or K562R), with BCR-ABL-dependent signaling pathways being repressed. Moreover, SH2-U-box worked in concert with imatinib in K562 cells. Importantly, SH2-U-box-carrying lentivirus could markedly suppress the growth of K562-xenografts in nude mice or K562R-xenografts in SCID mice, as well as that of primary CML cells. Collectively, by degrading the native and T315I-mutant BCR-ABL, the chimeric ubiquitin ligase SH2-U-box may serve as a potential therapy for both imatinib-sensitive and resistant CML.

An overview of chronic myeloid leukemia and its animal models

Chronic myeloid leukemia (CML) is a form of leukemia characterized by the presence of clonal bone marrow stem cells with the proliferation of mature granulocytes (neutrophils, eosinophils, and basophils) and their precursors. CML is a type of myeloproliferative disease associated with a characteristic chromosomal translocation called the Philadelphia (Ph) chromosome or t (9;22) translocation (BCR-ABL). CML is now usually treated with targeted drugs called tyrosine kinase inhibitors (TKIs). The mechanism and natural history of CML is still unclear. Here, we summarize the present CML animal disease models and compare them with each other. Meanwhile, we propose that it is a very wise choice to establish zebrafish (Danio rerio) CML model mimics clinical CML. This model could be used to learn more about the mechanism of CML, and to aid in the development of new drugs to treat CML.

GADS is required for TCR-mediated calcium influx and cytokine release, but not cellular adhesion, in human T cells

GRB2 related adaptor protein downstream of Shc (GADS) is a member of the GRB2 family of adaptors and is critical for TCR-induced signaling. The current model is that GADS recruits SLP-76 to the LAT complex, which facilitates the phosphorylation of SLP-76, the activation of PLC-γ1, T cell adhesion and cytokine production. However, this model is largely based on studies of disruption of the GADS/SLP-76 interaction and murine T cell differentiation in GADS deficient mice. The role of GADS in mediating TCR-induced signals in human CD4+ T cells has not been thoroughly investigated. In this study, we have suppressed the expression of GADS in human CD4+ HuT78 T cells. GADS deficient HuT78 T cells displayed similar levels of TCR-induced SLP-76 and PLC-γ1 phosphorylation but exhibited substantial decrease in TCR-induced IL-2 and IFN-γ release. The defect in cytokine production occurred because of impaired calcium mobilization due to reduced recruitment of SLP-76 and PLC-γ1 to the LAT complex. Surprisingly, both GADS deficient HuT78 and GADS deficient primary murine CD8+ T cells had similar TCR-induced adhesion when compared to control T cells. Overall, our results show that GADS is required for calcium influx and cytokine production, but not cellular adhesion, in human CD4+ T cells, suggesting that the current model for T cell regulation by GADS is incomplete.

The epigenetically-regulated miR-663 targets H-ras in K-562 cells

miR-663 is a tumour suppressor that is potentially regulated by modification of CpG islands. Whether aberrant methylation is one of the reasons for miR-663 down-regulation in some malignant cells and whether miR-663 targets oncogenes warrants further research. In the present study, we report that the CpG islands in the upstream region of pre-miR-663 are aberrantly methylated in the k-562 cell line and in the white blood cells of some chronic myelogenous leukaemia patients, and also that H-ras is one of the genes targeted by miR-663. Over-expression of miR-663 may suppress proliferation of the k-562 cell line in part by enhancing cell apoptosis.