Hypermethylation of SHP-1 promoter in patient with high-risk myelodysplastic syndrome and it predicts poor prognosis

Effects of PTPN6 Gene Knockdown in SKM-1 Cells on Apoptosis, Erythroid Differentiation and Inflammations

Objective: Protein tyrosine phosphatase non-receptor type 6 (PTPN6) is a cytoplasmic phosphatase that acts as a key regulatory protein in cell signaling to control inflammation and cell death. In order to investigate the role of PTPN6 in hematologic tumor myelodysplastic syndrome (MDS), this study infected SKM-1 cell line (MDS cell line) with packaged H_PTPN6-shRNA lentivirus to obtain H_PTPN6-shRNA SKM-1 stable strain. The effect of PTPN6 knockdown on apoptosis, erythroid differentiation, and inflammations in SKM-1 cell line was examined. Methods: The stable knockdown SKM-1 cell line was validated using qPCR and Western blot assays. The proliferation activity, apoptosi, erythroid differentiation, and inflammatory cytokines in SKM-1 cells were assessed before and after transfection. Results: qPCR confirmed that the expression level of H_PTPN6-shRNA in SKM-1 cells was significantly reduced, and Western blot showed that the protein expression level of H_PTPN6-shRNA in SKM-1 cells was also significantly reduced. The CCK-8 cell viability assay confirmed that stable gene knockdown did not affect cell viability. Flow cytometry revealed that the apoptosis rate of cells in the PTPN6 knockdown group was 0.8%, lower than the 2.7% observed in the empty plasmid group; the expression rate of the erythroid differentiation marker CD235a was 13.2%, lower than the 25.0% observed in the empty plasmid group. The expression levels of the proinflammatory factors IL-6 and IL-8 increased, and the expression levels of the inhibitor factor IL-4 decreased. Conclusions: The PTPN6 gene was successfully knocked down using lentivirus-mediated transduction, and the constructed cell line was validated using PCR and Western blot. The CCK-8 cell viability assay confirmed that stable gene knockdown did not affect cell proliferation viability. Flow cytometry analysis of apoptosis and erythroid differentiation indicated that PTPN6 knockdown inhibits apoptosis and erythroid differentiation in SKM-1 cells and also alters the level of inflammations in the bone marrow microenvironment. It suggests that the PTPN6 gene acts as a tumor suppressor in myelodysplastic syndrome cells, influencing hematopoietic cell apoptosis, erythroid differentiation, and inflammations. This provides a reliable experimental basis for further in-depth studies on the mechanism of PTPN6 in MDS and related pharmacological research.

Construction and experimental validation of a novel ferroptosis-related gene signature for myelodysplastic syndromes

BACKGROUND

Myelodysplastic syndromes (MDS) are clonal hematopoietic disorders characterized by morphological abnormalities and peripheral blood cytopenias, carrying a risk of progression to acute myeloid leukemia. Although ferroptosis is a promising target for MDS treatment, the specific roles of ferroptosis-related genes (FRGs) in MDS diagnosis have not been elucidated.

METHODS

MDS-related microarray data were obtained from the Gene Expression Omnibus database. A comprehensive analysis of FRG expression levels in patients with MDS and controls was conducted, followed by the use of multiple machine learning methods to establish prediction models. The predictive ability of the optimal model was evaluated using nomogram analysis and an external data set. Functional analysis was applied to explore the underlying mechanisms. The mRNA levels of the model genes were verified in MDS clinical samples by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

The extreme gradient boosting model demonstrated the best performance, leading to the identification of a panel of six signature genes: SREBF1, PTPN6, PARP9, MAP3K11, MDM4, and EZH2. Receiver operating characteristic curves indicated that the model exhibited high accuracy in predicting MDS diagnosis, with area under the curve values of 0.989 and 0.962 for the training and validation cohorts, respectively. Functional analysis revealed significant associations between these genes and the infiltrating immune cells. The expression levels of these genes were successfully verified in MDS clinical samples.

CONCLUSION

Our study is the first to identify a novel model using FRGs to predict the risk of developing MDS. FRGs may be implicated in MDS pathogenesis through immune-related pathways. These findings highlight the intricate correlation between ferroptosis and MDS, offering insights that may aid in identifying potential therapeutic targets for this debilitating disorder.

Synthesis and Biological Evaluation of 3-Amino-4,4-Dimethyl Lithocholic Acid Derivatives as Novel, Selective, and Cellularly Active Allosteric SHP1 Activators

Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP1), a non-receptor member of the protein tyrosine phosphatase (PTP) family, negatively regulates several signaling pathways that are responsible for pathological cell processes in cancers. In this study, we report a series of 3-amino-4,4-dimethyl lithocholic acid derivatives as SHP1 activators. The most potent compounds, 5az-ba, showed low micromolar activating effects (EC50: 1.54–2.10 μM) for SHP1, with 7.63–8.79-fold maximum activation and significant selectivity over the closest homologue Src homology 2 domain-containing protein tyrosine phosphatase 2 (SHP2) (>32-fold). 5az-ba showed potent anti-tumor effects with IC50 values of 1.65–5.51 μM against leukemia and lung cancer cells. A new allosteric mechanism of SHP1 activation, whereby small molecules bind to a central allosteric pocket and stabilize the active conformation of SHP1, was proposed. The activation mechanism was consistent with the structure–activity relationship (SAR) data. This study demonstrates that 3-amino-4,4-dimethyl lithocholic acid derivatives can be selective SHP1 activators with potent cellular efficacy.

Oncogenic Tyrosine Phosphatases: Novel Therapeutic Targets for Melanoma Treatment

Despite a large number of therapeutic options available, malignant melanoma remains a highly fatal disease, especially in its metastatic forms. The oncogenic role of protein tyrosine phosphatases (PTPs) is becoming increasingly clear, paving the way for novel antitumor treatments based on their inhibition. In this review, we present the oncogenic PTPs contributing to melanoma progression and we provide, where available, a description of new inhibitory strategies designed against these enzymes and possibly useful in melanoma treatment. Considering the relevance of the immune infiltrate in supporting melanoma progression, we also focus on the role of PTPs in modulating immune cell activity, identifying interesting therapeutic options that may support the currently applied immunomodulating approaches. Collectively, this information highlights the value of going further in the development of new strategies targeting oncogenic PTPs to improve the efficacy of melanoma treatment.

Shp1 in Solid Cancers and Their Therapy

Shp1 is a cytosolic tyrosine phosphatase that regulates a broad range of cellular functions and targets, modulating the flow of information from the cell membrane to the nucleus. While initially studied in the hematopoietic system, research conducted over the past years has expanded our understanding of the biological role of Shp1 to other tissues, proposing it as a novel tumor suppressor gene functionally involved in different hallmarks of cancer. The main mechanism by which Shp1 curbs cancer development and progression is the ability to attenuate and/or terminate signaling pathways controlling cell proliferation, survival, migration, and invasion. Thus, alterations in Shp1 function or expression can contribute to several human diseases, particularly cancer. In cancer cells, Shp1 activity can indeed be affected by mutations or epigenetic silencing that cause failure of Shp1-mediated homeostatic maintenance. This review will discuss the current knowledge of the cellular functions controlled by Shp1 in non-hematopoietic tissues and solid tumors, the mechanisms that regulate Shp1 expression, the role of its mutation/expression status in cancer and its value as potential target for cancer treatment. In addition, we report information gathered from the public available data from The Cancer Genome Atlas (TCGA) database on Shp1 genomic alterations and correlation with survival in solid cancers patients.

Deletion of MBD2 inhibits proliferation of chronic myeloid leukaemia blast phase cells

Aberrant methylation of tumour suppressor genes is associated with the progression to a blast crisis in chronic myeloid leukaemia (CML). Methyl-CpG-binding domain protein 2 (MBD2) has been studied as a "reader" of DNA methylation in many cancers, but its role in CML is unclear. We constructed cell models of a homozygous deletion mutation of MBD2 using gene-editing technology in K562 cells and BV173 cells. Here, we demonstrated that the deletion of MBD2 inhibited cell proliferation capacity in vitro. MBD2 deletion also significantly inhibited K562 cell proliferation in a xenograft tumour model in vivo. Additionally, the JAK2/STAT3 signalling pathway, which is abnormally active in CML, was inhibited by MBD2 deletion, and MBD2 deletion could up-regulate the expression of SHP1. In conclusion, our findings suggest that MBD2 is a candidate therapeutic strategy for the CML blast phase.

[Role of CXCR4/STAT3 in mesenchymal stromal cell-mediated drug resistance of acute leukemia cells]

OBJECTIVE

To explore the role of CXCR4/STAT3 in mesenchymal stromal cell (MSC)-mediated drug resistance of AML cells.

METHODS

AML cell lines U937 and KG1a and primary AML cells were co-cultured with MSC from bone marrow of healthy donors. The AML cell lines cultured alone were used as control. Apoptosis induced by mitoxantrone was measured by flow cytometry. Expression of CXCR4 and STAT3 protein were detected by Western blot. After incubated with STAT3 inhibitor Cucurbitacin I or CXCR4 antagonist AMD3100, the apoptosis of AML cells induced by mitoxantrone was evaluated.

RESULTS

Apoptosis of AML cells (U937 and KG1a) and primary AML cells induced by mitoxantrone significantly decreased in cocultured group than that of control group [U937 cells: (20.08±1.53)% vs (45.33 ± 1.03)% , P=0.004; KG1a cells: (25.60 ± 1.82)% vs (40.33 ± 3.29)% , P=0.020]. Expression of phosphorylated STAT3 and CXCR4 protein in AML cells were upregulated in cocultured group. After addition of Cucurbitacin I into the co-culture system, the apoptosis rate of primary AML cells significantly increased. Similar results of the apoptosis rates were also detected when the inhibitor of CXCR4 AMD3100 was added to overcome the stromal cell-mediated drug resistance. Besides, the expression of p-STAT3 in AML cells after incubated with AMD3100 decreased significantly.

CONCLUSIONS

AML cells cocultured with MSC leads to the up-regulation of phosphorylated STAT3 and CXCR4 proteins, which resulted in AML cells resistance to chemotherapeutic drugs. Therefore targeting STAT3 or CXCR4 could be a new therapeutic strategy of AML.