Wip1 knockout inhibits the proliferation and enhances the migration of bone marrow mesenchymal stem cells

WIP1-mediated regulation of p38 MAPK signaling attenuates pyroptosis in sepsis-associated acute kidney injury

Wild-Type p53-Induced Phosphatase 1 (WIP1/PPM1D) is a serine/threonine phosphatase that plays a significant role in various physiological processes. However, the involvement of WIP1 in kidney remains unclear. Lipopolysaccharide (LPS) was administered to induce acute injury in mice and human kidney 2 (HK2) cells in the study. The WIP1 inhibitor, CCT007093, was administered both in vitro and in vivo to assess its effect on kidney. The single-cell sequencing (scRNA-seq) data revealed that Ppm1d mRNA reached peak on day 2 following unilateral ischemia-reperfusion injury (uni-IRI) in mice, especially in the proximal renal tubules during repair phase. Compared to the control group, WIP1 protein exhibited a significant increase in renal tubules of patients with acute tubular injury (ATI) and mice with LPS-induced acute kidney injury (AKI), as well as in LPS-injured HK2 cells. In vitro experiments showed that CCT007093 increased the protein levels of NLRP3, cleaved-Caspase1, GSDMD-N and IL-1β in HK2 cells and further reduced the viability of LPS-stimulated HK2 cells. In vivo experiments showed that inhibition of WIP1 activity with CCT007093 further increased cleaved-Caspase1, GSDMD-N protein levels in kidney tissue from mice with LPS-induced AKI. In addition, LPS induces phosphorylation of p38 MAPK, a key regulator of pyroptosis, which is further activated by CCT007093. In conclusion, inhibition of WIP1 activity acts as a positive regulator of renal tubular pyroptosis mainly through the mediation of phospho-p38 MAPK.

Wip1 regulates wound healing by affecting activities of keratinocytes and endothelial cells through ATM-p53 and mTOR signaling

BACKGROUND

As a p53-regulated gene, Wip1 regulates proliferation, migration, apoptosis, and senescence of several type cells, but its biological functions in keratinocytes and endothelial cells which are involved wound healing are not fully understood. This study aims to reveal the function and underlying mechanism of Wip1 in wound healing using models of transgenic animal, keratinocytes, and endothelial cells.

METHODS

Using Wip1 knockout C57 BL/6 mice, we investigated effect of Wip1 deficiency on wound healing and angiogenesis; And using HaCaT and HUVEC as keratinocytes and endothelial cells, combined using primary keratinocytes from Wip1 knockout mice, we studied the effects of Wip1 knockdown/knockout or overexpression on proliferation, migration, and protein expressions of signaling components in ATM-p53 and mTOR pathway.

RESULTS

Wip1 deficiency in mice impaired the wound repair and endothelial angiogenesis, reduced the thickness of granulation tissue, and decreased the number of Ki67-positive cells and CD31 positive vessels in granulation tissue. Knockdown of Wip1 by shRNAs suppressed the proliferation and migration of HaCaT and HUVEC cells and induced notably apoptosis in the two cells. In western blot, Wip1 knockdown enriched p53 and ATM proteins, while decreased activated AKT, mTOR and activated S6 ribosomal protein (pS6) levels in HaCaT and HUVEC cells. Ectopic expression of Wip1 decreased the p53 and ATM proteins, while increased activated AKT, mTOR and pS6 levels in HaCaT and HUVEC cells. And in primary keratinocytes from mice tail skin, Wip1 knockout increased p53 and ATM, while decreased activated AKT, mTOR and pS6 protein levels.

CONCLUSION

Our study directly supports that Wip1 regulated skin wound healing possibly by affecting bioactivities including proliferation, migration and apoptosis of keratinocytes and endothelial cells at least through by modulating ATM-p53 and mTOR signaling.

CDK5RAP2 loss-of-function causes premature cell senescence via the GSK3β/β-catenin-WIP1 pathway

Developmental disorders characterized by small body size have been linked to CDK5RAP2 loss-of-function mutations, but the mechanisms underlying which remain obscure. Here, we demonstrate that knocking down CDK5RAP2 in human fibroblasts triggers premature cell senescence that is recapitulated in Cdk5rap2^an/an mouse embryonic fibroblasts and embryos, which exhibit reduced body weight and size, and increased senescence-associated (SA)-β-gal staining compared to Cdk5rap2^+/+ and Cdk5rap2^+/an embryos. Interestingly, CDK5RAP2-knockdown human fibroblasts show increased p53 Ser15 phosphorylation that does not correlate with activation of p53 kinases, but rather correlates with decreased level of the p53 phosphatase, WIP1. Ectopic WIP1 expression reverses the senescent phenotype in CDK5RAP2-knockdown cells, indicating that senescence in these cells is linked to WIP1 downregulation. CDK5RAP2 interacts with GSK3β, causing increased inhibitory GSK3β Ser9 phosphorylation and inhibiting the activity of GSK3β, which phosphorylates β-catenin, tagging β-catenin for degradation. Thus, loss of CDK5RAP2 decreases GSK3β Ser9 phosphorylation and increases GSK3β activity, reducing nuclear β-catenin, which affects the expression of NF-κB target genes such as WIP1. Consequently, loss of CDK5RAP2 or β-catenin causes WIP1 downregulation. Inhibition of GSK3β activity restores β-catenin and WIP1 levels in CDK5RAP2-knockdown cells, reducing p53 Ser15 phosphorylation and preventing senescence in these cells. Conversely, inhibition of WIP1 activity increases p53 Ser15 phosphorylation and senescence in CDK5RAP2-depleted cells lacking GSK3β activity. These findings indicate that loss of CDK5RAP2 promotes premature cell senescence through GSK3β/β-catenin downregulation of WIP1. Premature cell senescence may contribute to reduced body size associated with CDK5RAP2 loss-of-function.

Integrated analysis of DNA methylome and transcriptome reveals the differences in biological characteristics of porcine mesenchymal stem cells

BACKGROUND

Bone marrow (BM) and umbilical cord (UC) are the main sources of mesenchymal stem cells (MSCs). These two MSCs display significant differences in many biological characteristics, yet the underlying regulation mechanisms of these cells remain largely unknown.

RESULTS

BMMSCs and UCMSCs were isolated from inbred Wuzhishan miniature pigs and the first global DNA methylation and gene expression profiles of porcine MSCs were generated. The osteogenic and adipogenic differentiation ability of porcine BMMSCs is greater than that of UCMSCs. A total of 1979 genes were differentially expressed and 587 genes were differentially methylated at promoter regions in these cells. Integrative analysis revealed that 102 genes displayed differences in both gene expression and promoter methylation. Gene ontology enrichment analysis showed that these genes were associated with cell differentiation, migration, and immunogenicity. Remarkably, skeletal system development-related genes were significantly hypomethylated and upregulated, whereas cell cycle genes were opposite in UCMSCs, implying that these cells have higher cell proliferative activity and lower differentiation potential than BMMSCs.

CONCLUSIONS

Our results indicate that DNA methylation plays an important role in regulating the differences in biological characteristics of BMMSCs and UCMSCs. Results of this study provide a molecular theoretical basis for the application of porcine MSCs in human medicine.

MiR-145-5p Inhibits the Invasion of Prostate Cancer and Induces Apoptosis by Inhibiting WIP1

Prostate cancer (PCa) is a common malignant tumor of the male genitourinary system that seriously affects the quality of life of patients. Studying the pathogenesis and therapeutic targets of PCa is important. In this study, we investigated the role of miR-145-5p in PCa and its potential molecular mechanisms. The expression levels of miR-145-5p in PCa tissues and adjacent control tissues were detected by real-time quantitative polymerase chain reaction. The effects of miR-145-5p overexpression on PCa were studied using cell proliferation, migration, and invasion experiments. Furthermore, WIP1 was the target gene of miR-145-5p through the bioinformatics website and dual-luciferase reporter gene experiment. Further studies found that WIP1 downregulation could inhibit the proliferation, invasion, and cloning of PCa cells. Overexpression of WIP1 reversed the anticancer effects of miR-145. The anticancer effect of miR-145 was achieved by inhibiting the PI3K/AKT signaling pathway and upregulating ChK2 and p-p38MAPK. Taken together, these results confirmed that miR-145-5p inhibited the growth and metastasis of PCa cells by inhibiting the expression of proto-oncogene WIP1, thereby playing a role in tumor suppression in PCa and may become a potential therapeutic target for the treatment of PCa.

Wip1 regulates the immunomodulatory effects of murine mesenchymal stem cells in type 1 diabetes mellitus via targeting IFN-α/BST2

Mesenchymal stem cells (MSCs) show significant therapeutic effects in type 1 diabetes mellitus (T1DM) as regulating the inflammatory processes. However, little is known about the detailed process of MSCs immunosuppression in T1DM. In this study, we investigated the effects of wild-type p53-induce phosphatase 1 (Wip1) on regulating MSCs immunosuppressive capacities in T1DM mice. We found that Wip1 knockout (Wip1-/-) MSCs had lower therapeutic effects in T1DM mice, and displayed weaker immunosuppressive capability. In vivo distribution analysis results indicated thatWip1-/-MSCs could home to the damaged pancreas and increase the expression of tumor necrosis factor-α (TNF-α), interleukin-17a (IL-17a), interferon-α(IFN-α), IFN-β, and IFN-γ, while decrease the expression of IL-4 and IL-10. Moreover, we confirmedWip1-/-MSCs exhibited weaker immunosuppressive capacity, as evidenced by enhanced expression of bone marrow stromal cell antigen 2(BST2) and IFN-α. In conclusion, these results revealed Wip1 affects MSCs immunomodulation by regulating the expression of IFN-α/BST2. Our study uncovered that Wip1 is required to regulate the therapeutic effects of MSCs on T1DM treatment, indicating a novel role of Wip1 in MSCs immunoregulation properties.

PPM1D is a potential prognostic biomarker and correlates with immune cell infiltration in hepatocellular carcinoma

Background: Protein phosphatase magnesium-dependent 1 delta (PPM1D), also referred to as wild-type p53-induced phosphatase 1 (Wip1) or protein phosphatase 2C delta (PP2Cδ), is an oncogenic nuclear serine/threonine phosphatase belonging to the PP2C family. However, the knowledge regarding PPM1D mRNA expression, tumor immunity, and the prognosis in hepatocellular carcinoma (HCC) is scanty.

Methods: We analyzed PPM1D, including its expression in both the normal and tumor tissue using the Sangerbox database and Tumor Immune Estimation Resource (TIMER). We evaluated its correlation with prognosis in different tumor types by the Kaplan-Meier plotter and Gene Expression Profiling Interactive Analysis (GEPIA). The correlations between PPM1D and the cancer immune infiltrates were determined using TIMER. The correlations between PPM1D expression and gene marker sets of the immune infiltrates were established by both the TIMER and GEPIA. Immunohistochemistry was performed to detect the expression of Wip1 protein encoded by PPM1D in HCC, and the relationship between Wip1 expression and the prognosis of HCC were analyzed.

Results: We found out that PPM1D mRNA expression was significantly higher in several human cancers, including HCC, than in the corresponding normal human tissues. The PPM1D mRNA high expression in HCC was significantly correlated with poor prognosis. The expression was associated with progression-free survival (PFS) in multiple HCC patients’ cohorts (PFS HR = 1.5, P = 0.0066). This was especially in early stage (stage 1) and AJCC_T 1 of HCC. Besides, PPM1D mRNA expression indicated a positive correlation with tumor-infiltrating Monocytes, tumor-associated macrophages (TAMs), M1 Macrophage, M2 Macrophage, dendritic cells (DCs), T-helper (Th) and Treg. Wip1 was higher in HCC than paracancerous tissue. High expression of Wip1 was associated with poor prognosis of HCC.

Conclusion: Our findings suggested that PPM1D mRNA is critical in activating tumor immunity. Besides, they implied that PPM1D could be a potential prognostic biomarker for cancer progression. Moreover, it correlated with tumor immune cell infiltration in HCC.

Adult mesenchymal stem cell ageing interplays with depressed mitochondrial Ndufs6

Mesenchymal stem cell (MSC)-based therapy has emerged as a novel strategy to treat many degenerative diseases. Accumulating evidence shows that the function of MSCs declines with age, thus limiting their regenerative capacity. Nonetheless, the underlying mechanisms that control MSC ageing are not well understood. We show that compared with bone marrow-MSCs (BM-MSCs) isolated from young and aged samples, NADH dehydrogenase (ubiquinone) iron-sulfur protein 6 (Ndufs6) is depressed in aged MSCs. Similar to that of Ndufs6 knockout (Ndufs6^−/−) mice, MSCs exhibited a reduced self-renewal and differentiation capacity with a tendency to senescence in the presence of an increased p53/p21 level. Downregulation of Ndufs6 by siRNA also accelerated progression of wild-type BM-MSCs to an aged state. In contrast, replenishment of Ndufs6 in Ndufs6^−/−-BM-MSCs significantly rejuvenated senescent cells and restored their proliferative ability. Compared with BM-MSCs, Ndufs6^−/−-BM-MSCs displayed increased intracellular and mitochondrial reactive oxygen species (ROS), and decreased mitochondrial membrane potential. Treatment of Ndufs6^−/−-BM-MSCs with mitochondrial ROS inhibitor Mito-TEMPO notably reversed the cellular senescence and reduced the increased p53/p21 level. We provide direct evidence that impairment of mitochondrial Ndufs6 is a putative accelerator of adult stem cell ageing that is associated with excessive ROS accumulation and upregulation of p53/p21. It also indicates that manipulation of mitochondrial function is critical and can effectively protect adult stem cells against senescence.

Metal-dependent Ser/Thr protein phosphatase PPM family: Evolution, structures, diseases and inhibitors

Protein phosphatases and kinases control multiple cellular events including proliferation, differentiation, and stress responses through regulating reversible protein phosphorylation, the most important post-translational modification. Members of metal-dependent protein phosphatase (PPM) family, also known as PP2C phosphatases, are Ser/Thr phosphatases that bind manganese/magnesium ions (Mn²⁺/Mg²⁺) in their active center and function as single subunit enzymes. In mammals, there are 20 isoforms of PPM phosphatases: PPM1A, PPM1B, PPM1D, PPM1E, PPM1F, PPM1G, PPM1H, PPM1J, PPM1K, PPM1L, PPM1M, PPM1N, ILKAP, PDP1, PDP2, PHLPP1, PHLPP2, PP2D1, PPTC7, and TAB1, whereas there are only 8 in yeast. Phylogenetic analysis of the DNA sequences of vertebrate PPM isoforms revealed that they can be divided into 12 different classes: PPM1A/PPM1B/PPM1N, PPM1D, PPM1E/PPM1F, PPM1G, PPM1H/PPM1J/PPM1M, PPM1K, PPM1L, ILKAP, PDP1/PDP2, PP2D1/PHLPP1/PHLPP2, TAB1, and PPTC7. PPM-family members have a conserved catalytic core region, which contains the metal-chelating residues. The different isoforms also have isoform specific regions within their catalytic core domain and terminal domains, and these regions may be involved in substrate recognition and/or functional regulation of the phosphatases. The twenty mammalian PPM phosphatases are involved in regulating diverse cellular functions, such as cell cycle control, cell differentiation, immune responses, and cell metabolism. Mutation, overexpression, or deletion of the PPM phosphatase gene results in abnormal cellular responses, which lead to various human diseases. This review focuses on the structures and biological functions of the PPM-phosphatase family and their associated diseases. The development of specific inhibitors against the PPM phosphatase family as a therapeutic strategy will also be discussed.

Wild-type p53-induced phosphatase 1 promotes vascular smooth muscle cell proliferation and neointima hyperplasia after vascular injury via p-adenosine 5'-monophosphate-activated protein kinase/mammalian target of rapamycin complex 1 pathway

OBJECTIVES

Vascular smooth muscle cell (VSMC) proliferation is a crucial cause of vascular neointima hyperplasia and restenosis, thus limiting the long-term efficacy of percutaneous vascular intervention. We explored the role of wild-type p53-induced phosphatase 1 (Wip1), a potent regulator of tumorigenesis and atherosclerosis, in VSMC proliferation and neointima hyperplasia.

METHODS AND RESULTS

Animal model of vascular restenosis was established in wild type C57BL/6J and VSMC-specific Tuberous Sclerosis 1 (TSC1)-knockdown mice by wire injury. We observed increased protein levels of Wip1, phospho (p)-S6 Ribosomal Protein (S6), p-4EBP1 but decreased p-adenosine 5'-monophosphate-activated protein kinase (AMPK)α both in carotid artery at day 28 after injury and in VSMCs after 48 h of platelet derived growth factor-BB (PDGF-BB) treatment. By using hematoxylin-eosin staining, Ki-67 immunohistochemical staining, cell counting kit-8 assay and Ki-67 immunofluorescence staining, we found Wip1 antagonist GSK2830371 (GSK) or mammalian target of rapamycin complex 1 (mTORC1) inhibitor rapamycin both obviously reversed the neointima formation and VSMC proliferation induced by wire injury and PDGF-BB, respectively. GSK also reversed the increase in mRNA level of Collagen I after wire injury. However, GSK had no obvious effects on VSMC migration induced by PDGF-BB. Simultaneously, TSC1 knockdown as well as AMPK inhibition by Compound C abolished the vascular protective and anti-proliferative effects of Wip1 inhibition. Additionally, suppression of AMPK also reversed the declined mTORC1 activity by GSK.

CONCLUSION

Wip1 promotes VSMC proliferation and neointima hyperplasia after wire injury via affecting AMPK/mTORC1 pathway.

Integrative Proteomic and Phosphoproteomic Profiling of Testis from Wip1 Phosphatase-Knockout Mice: Insights into Mechanisms of Reduced Fertility

Mice lacking wild-type p53-induced phosphatase 1 (Wip1) display male reproductive defects including smaller testes, subfertility and spermatogenesis defects at the round- and elongating-spermatid stages. However, the molecular mechanisms underlying these abnormalities remain unclear. Here we examined the proteome and phosphoproteome of testes from Wip1-knockout mice using a quantitative proteomic approach. From a total of 6872 proteins and 4280 phosphorylation sites identified, 58 proteins and 159 phosphorylation sites were found to be differentially regulated compared with wild type mice. Pathway enrichment analyses revealed that these regulated proteins and phosphosites were mainly involved in adherens/tight junctions, apoptosis, inflammatory response, spermatogenesis, sperm motility, and cytoskeletal assembly and depolymerization. Wip1-knockout mice showed decreased expression of junction-associated proteins (occludin, ZO-1, and N-cadherin) and impaired integrity of the blood-testis barrier. In addition, Wip1 deficiency was associated with elevated levels of cytokines and germ cell apoptosis in the testis. These results suggest that proinflammatory cytokines may impair the blood-testis barrier dynamics by decreasing the expression of junction-associated proteins, which could lead to subfertility and spermatogenesis defects. Collectively, these findings help to explain the low reproductive function caused by Wip1 deletion and provide novel insights into our understanding of causes of male infertility.

Thymoquinone influences the expression of genes involved in self-renewal and immunomodulatory potential of mouse bone marrow-derived mesenchymal stem cells in vitro

Thymoquinone (TQ) is an active ingredient of some medicinal herbs. Despite extensive studies on the biological and pharmacological properties of TQ, its effect on the characteristics of stem cells remains to be clarified. Therefore, this study was aimed to investigate the effect of TQ on viability, proliferation and immunomodulatory potential of mouse bone marrow-derived mesenchymal stem cells (BM-MSCs) in vitro. The BM-MSCs were isolated from young NMRI mice. The cytotoxic effect of TQ on the BM-MSCs was evaluated using MTT assay. Then, the effect of TQ on the proliferation of BM-MSCs and the mRNA expression of genes involved in self-renewal and immunomodulatory potential of MSCs was assessed by the cell counting and real-time PCR assays. Results showed that TQ reduces the number of BM-MSCs in a dose- and time-dependent manner. In addition, the half-maximal inhibitory concentration values of TQ on the BM-MSCs were 8 μg/ml at 24h and 4 μg/ml at 48 and 72h after treatment. Furthermore, about 90% of the BM-MSCs were alive after treatment with concentrations ≤2 μg/ml of TQ for 24h. The results of cell counting assay indicated that TQ at concentrations of 1-2 μg/ml significantly enhanced the proliferation of BM-MSCs (P < 0.05). The gene expression analysis also showed that Tlr3, Tlr4, Ccl2, Ccl3, Sox2, and Rex1 are overexpressed (Fold change ≥1.5) in the TQ-treated BM-MSCs compared with the untreated samples. In conclusion, these findings propose that TQ may regulate self-renewal and immunomodulatory potential of MSCs. However, the exact mechanisms and the roles of this regulation are required to be elucidated in further study.

Expression of wild-type p53-induced phosphatase 1 in diabetic epiretinal membranes

Objective

The aims of the present study were to investigate the expression and distribution of Wild-type p53-induced phosphatase 1 (Wip1) in diabetic patients with proliferative diabetic retinopathy (PDR) with epiretinal membranes (ERMs) meanwhile analyze the colocalization of Wip1 and nuclear factor kappa-B (NF-κB) p65 in ERMs.

Methods

ERMs samples were collected from patients with PDR (PDR group) or non-diabetic patients with idiopathic epiretinal membranes (iERMs) (control group) during pars plana vitrectomy. Real-Time PCR analysis was carried out to examine the mRNA expression of Wip1 in ERMs. Immunohistochemical analysis and Immunofluorescent analysis were performed to detect the protein expression of Wip1 in ERMs. Double immunofluorescent staining was performed to detect the colocalization of Wip1 and glial fibrillary acidic protein (GFAP) (retinal glial cells marker), also Wip1 and NF-κB.

Results

ERMs were obtained from 17 eyes of 17 patients with PDR (the PDR group) and 9 eyes of 9 nondiabetic patients (the control group) with iERMs. Our results showed high expression levels of Wip1 mRNAs in ERMs after PDR, but low in iERMs. In addition, both immunohistochemistry and immunofluorescence assay showed strong immunoreactivity for Wip1 in PDR ERMs. Furthermore, Wip1 and GFAP were coexpressed in PDR membranes. Finally, the expression of Wip1 was paralleled with NF-κB.

Conclusion

These data support the notion that Wip1 contributes to the formation of the ERMs in PDR membranes via NF-κB signaling.

Eugenol enhances proliferation and migration of mouse bone marrow-derived mesenchymal stem cells in vitro

Mesenchymal stem cells (MSCs) have received considerable attention in regenerative medicine during the past decade. Eugenol is a natural and versatile vegetable molecule, which has a wide variety of therapeutic effects. Although different biological and pharmaceutical functions of Eugenol are well known, its effect on MSCs has not been studied yet. Therefore, this study was focused on investigating the effect of Eugenol on the proliferation and migration of bone marrow (BM)-derived MSCs in vitro. To do so, BM-MSCs were isolated from 4 to 8 weeks old NMRI mice. Cytotoxicity of Eugenol on MSCs was evaluated by MTT assay at 24, 48 and 72 h after treatment. In addition, its effect was assessed on the proliferation and migration of MSCs using wound healing assay in vitro and quantitative gene expression analysis for Oct4, Sox2, Cyclin-D1, Rex1, Tex10, Cxcr4, Vla4 and c-Met. Results showed that Eugenol reduced the number of MSCs in a dose- and time-dependent manner. The median inhibition concentration of Eugenol on MSCs was 400 μg/ml at 24 and 48 h and 200 μg/ml at 72 h after treatment. Moreover, about 90% viability of MSCs was detected at concentrations ≤12.5 μg/ml. The wound healing assay and gene expression analysis demonstrated that Eugenol promoted the migratory potential of MSCs through up-regulation of c-Met. Moreover, Eugenol has enhanced the proliferation of MSCs via over-expression of Sox2, Rex1 and Tex10. In conclusion, this study revealed that Eugenol enhances the proliferation and migration of MSCs, and thus this will be beneficial to the field of regenerative medicine.

Wip1 suppresses ovarian cancer metastasis through the ATM/AKT/Snail mediated signaling

Inactivation of p53 greatly contributes to serous ovarian cancer, while the role of the wild-type p53 induced phosphatase 1 (Wip1) is quite unclear. In this study, by silencing or overexpression of Wip1, we found that Wip1 suppressed ovarian cancer cell invasion, migration, epithelial to mesenchymal transition (EMT), and ovarian cancer metastasis in xenograft animal models. Mechanistic studies showed that Wip1 may block ovarian cancer metastasis through inhibition of Snail and p-Akt expression because silencing or overexpression of Wip1 either upregulated or downregulated the expression of Snail and p-Akt (Ser 473), while further knockdown of Snail by shRNA or inhibition of p-Akt by a chemical compound attenuated cell invasion, migration and EMT in Wip1 silencing cells. We also found that the phosphorylation of Akt at Ser 473 might be mediated through p-ATM (Ser 1981). Thus, Wip1 may suppress ovarian cancer metastasis through negative regulation of p-ATM, p-Akt, and Snail, which was also evidenced in the limited clinical specimens. Therefore, our data may provide a novel therapeutic indication for serous ovarian cancer based on the uncovered mechanism associated with the precise function of Wip1 independent of p53.

Wip1: A candidate phosphatase for cancer diagnosis and treatment

The critical regulatory mechanisms in numerous cellular pathways including cell survival and DNA damage response mostly depend on phosphorylation and dephosphorylation of proteins. The serine/threonine phosphatase wild-type p53-induced phosphatase 1 (Wip1) is a growth-promoting phosphatase and its numerous downstream targets are important tumor suppressors. Here, we review the Wip1 activity and its relevance to cancer as an oncoprotein. Consecutive investigations about Wip1 and its relation to cancer is critical, as these studies ultimately contribute to the etiology of cancer. A number of innovative studies have recently investigated the importance of Wip1 as a new candidate for cancer diagnosis and prognosis. Accordingly, we discuss the present challenges of using Wip1 as a target for cancer treatment.

Combination of lentivirus-mediated silencing of PPM1D and temozolomide chemotherapy eradicates malignant glioma through cell apoptosis and cell cycle arrest

Temozolomide (TMZ) is approved for use as first-line treatment for glioblastoma multiforme (GBM). However, GBM shows chemoresistance shortly after the initiation of treatment. In order to detect whether silencing of human protein phosphatase 1D magnesium dependent (PPM1D) gene could increase the effects of TMZ in glioma cells, glioma cells U87-MG were infected with lentiviral shRNA vector targeting PPM1D silencing. After PPM1D silencing was established, cells were treated with TMZ. The multiple functions of human glioma cells after PPM1D silencing and TMZ chemotherapy were detected by flow cytometry and MTT assay. Significantly differentially expressed genes were distinguished by microarray-based gene expression profiling and analyzed by gene pathway enrichment analysis and ontology assessment. Western blotting was used to establish the protein expression of the core genes. PPM1D gene silencing improves TMZ induced cell proliferation and induces cell apoptosis and cell cycle arrest. When PPM1D gene silencing combined with TMZ was performed in glioma cells, 367 genes were upregulated and 444 genes were downregulated compared with negative control. The most significant differential expression pathway was pathway in cancer and IGFR1R, PIK3R1, MAPK8 and EP300 are core genes in the network. Western blotting showed that MAPK8 and PIK3R1 protein expression levels were upregulated and RB1 protein expression was decreased. It was consistent with that detected in gene expression profiling. In conclusion, PPM1D gene silencing combined with TMZ eradicates glioma cells through cell apoptosis and cell cycle arrest. PIK3R1/AKT pathway plays a role in the multiple functions of glioma cells after PPM1D silencing and TMZ chemotherapy.