Studies in Western countries have repeatedly shown that women with a history of childhood sexual abuse (CSA) are at increased risk for developing major depression (MD). Would this relationship be found in China?
Three levels of CSA (non-genital, genital, and intercourse) were assessed by self-report in two groups of Han Chinese women: 1970 clinically ascertained with recurrent MD and 2597 matched controls. Diagnostic and other risk factor information was assessed at personal interview. Odds ratios (ORs) were calculated by logistic regression and regression coefficients by linear or Poisson regression.
Any form of CSA was significantly associated with recurrent MD [OR 3.26, 95% confidence interval (CI) 1.95–5.45]. This association strengthened with increasing CSA severity: non-genital (OR 2.47, 95% CI 1.17–5.23), genital (OR 2.77, 95% CI 1.32–5.83) and intercourse (OR 13.35, 95% CI 1.83–97.42). The association between any form of CSA and MD remained significant after accounting for parental history of depression, childhood emotional neglect (CEN), childhood physical abuse (CPA) and parent–child relationship. Among the depressed women, those with CSA had an earlier age of onset, longer depressive episodes and an increased risk for generalized anxiety disorder (GAD; OR 1.92, 95% CI 1.39–2.66) and dysthymia (OR 2.16, 95% CI 1.52–3.09).
In Chinese women CSA is strongly associated with MD and this association increases with greater severity of CSA. Depressed women with CSA have an earlier age of onset, longer depressive episodes and increased co-morbidity with GAD and dysthymia. Although reporting biases cannot be ruled out, our results are consistent with the hypothesis that, as in Western countries, CSA substantially increases the risk for MD in China.
Childhood sexual abuse; co-morbidity; major depression
Mutations in HBx gene are frequently found in HBV-associated hepatocellular carcinoma (HCC). Activation of hypoxia-inducible factor-1α (HIF-1α) contributes to HCC development and progression. Wild-type HBx has been demonstrated to activate HIF-1α, but the effect of HBx mutations on HIF-1α has not been elucidated.
HBx mutations were identified by gene sequencing in 101 HCC tissues. Representative HBx mutants were cloned and transfected into HCC cells. Expression and activation of HIF-1α were analysed by western blot and luciferase assays, respectively. The relationship between HBx mutants and HIF-1α expression in HCC tissues was also evaluated.
The dual mutations K130M/V131I enhanced the functionality of HBx as they upregulated the expression and transcriptional activity of HIF-1α. The C-terminal truncations and deletion mutations, however, weakened the ability of HBx to upregulate HIF-1α. Meanwhile, the C-terminus was further found to be essential for the stability and transactivation of HBx. In the HCC tissues, there was a positive association between the HBx mutants and HIF-1α expression.
Different mutations of HBx exert differentiated effects on the functionality of HIF-1α, however, the overall activity of HBx mutants appears to increase the expression and transcriptional activity of HIF-1α.
HBx; HIF-1α; mutation; hepatocellular carcinoma
p15INK4B, a cyclin-dependent kinase inhibitor, has been recognized as a tumor
suppressor. Loss of or methylation of the p15INK4B gene in chronic
myeloid leukemia (CML) cells enhances myeloid progenitor formation from common
myeloid progenitors. Therefore, we examined the effects of overexpressed p15INK4B on
proliferation and apoptosis of CML cells. Overexpression of p15INK4B inhibited the
growth of K562 cells by downregulation of cyclin-dependent kinase 4 (CDK4) and cyclin
D1 expression. Overexpression of p15INK4B also induced apoptosis of K562 cells by
upregulating Bax expression and downregulating Bcl-2 expression. Overexpression of
p15INK4B together with STI571 (imatinib) or BCR-ABL1 small interfering RNA (siRNA)
also enhanced growth inhibition and apoptosis induction of K562 cells. The enhanced
effect was also mediated by reduction of cyclin D1 and CDK4 and regulation of Bax and
Bcl-2. In conclusion, our study may provide new insights into the role of p15INK4B in
CML and a potential therapeutic target for overcoming tyrosine kinase inhibitor
resistance in CML.
Apoptosis; Chronic myeloid leukemia; p15INK4B; STI571 (Gleevec, imatinib)
Giant cell tumor of bone (GCTB) is a very rare tumor entity, which is little examined owing to the lack of established cell lines and mouse models and the restriction of available primary cell lines. The stromal cells of GCTB have been made responsible for the aggressive growth and metastasis, emphasizing the presence of a cancer stem cell population. To identify and target such tumor-initiating cells, stromal cells were isolated from eight freshly resected GCTB tissues. Tumorigenic properties were examined by colony and spheroid formation, differentiation, migration, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, immunohistochemistry, antibody protein array, Alu in situ hybridization, FACS analysis and xenotransplantation into fertilized chicken eggs and mice. A sub-population of the neoplastic stromal cells formed spheroids and colonies, differentiated to osteoblasts, migrated to wounded regions and expressed the metastasis marker CXC-chemokine receptor type 4, indicating self-renewal, invasion and differentiation potential. Compared with adherent-growing cells, markers for pluripotency, stemness and cancer progression, including the CSC surface marker c-Met, were enhanced in spheroidal cells. This c-Met-enriched sub-population formed xenograft tumors in fertilized chicken eggs and mice. Cabozantinib, an inhibitor of c-Met in phase II trials, eliminated CSC features with a higher therapeutic effect than standard chemotherapy. This study identifies a c-Met+ tumorigenic sub-population within stromal GCTB cells and suggests the c-Met inhibitor cabozantinib as a new therapeutic option for targeted elimination of unresectable or recurrent GCTB.
Live combined Bacillus subtilis and Enterococcus faecium ameliorate murine experimental colitis by immunosuppression manifested by downregulation of TLRs, macrophages, Th1, and Th2 but upregulation of Tregs.
Sirolimus (rapamycin) is an immunosuppressive agent commonly used in transplant recipients. Although sirolimus has less renal toxicity than calcineurin inhibitors, its use has been limited by its side effects. The most common cutaneous pathologies associated with sirolimus are inflammatory acneiform eruptions, lymphedema and aphthous ulcers. We present a novel cutaneous manifestation of sirolimus therapy that limited its use in at least one transplant recipient. Upon commencing sirolimus therapy, four solid organ transplant recipients developed tender, nonpruritic palmoplantar peeling within the first month of therapy. The peeling clinically resembled a mild form of hand-foot syndrome, yet none of the patients had been treated with chemotherapeutics. Desquamation presented on the palms and soles with dry vesicles and minor peeling extending to the dorsal aspects of the hands and feet. Histologically, the lesions were noninflammatory; the epidermis showed subtle separation between keratinocytes, suggesting either spongiosis or a defect in intercellular adhesion. One patient opted to discontinue treatment because of the tenderness associated with the palmoplantar peeling, which resulted in complete resolution within 2 weeks.
Acral; desquamation; palmoplantar; peeling; rapamycin; sirolimus
Optic neuritis (ON) cases have been reported in patients using anti-tumor necrosis factor (TNF) alpha therapy. However, no population-based studies have been conducted to assess the risk of this complication associated with anti-TNF drugs.
New users of anti-TNF therapy (etanercept, infliximab, or adalimumab) or non-biologic disease modifying agents (DMARDs) during 2000–2007 from the following data sources: Kaiser Permanente Northern California, Pharmaceutical Assistance Contract for the Elderly, Tennessee Medicaid, and National Medicaid/Medicare.
We used validated algorithms to identify ON cases occurring after onset of new drug exposure. We calculated and compared ON rates between exposure groups.
Main outcome measures
ON incidence rates by medication exposure group
We identified 61,227 eligible inflammatory disease patients with either new anti-TNF or new non-biologic DMARD use. Among this cohort, we found three ON cases among anti-TNF new users, occuring a median 123 days (range, 37–221 days) after anti- TNF start. The crude incidence rate of ON across all disease indications among anti-TNF new users was 10.4 (95% CI 3.3–32.2) cases per 100,000 person-years. In a sensitivity analysis considering current or past anti-TNF or DMARD use, we identified a total of 6 ON cases; 3 among anti-TNF users and 3 among DMARD users. Crude ON rates were similar among anti-TNF and DMARD groups, 4.5 (95% CI 1.4–13.8) and 5.4 (95% CI 1.7–16.6) per 100,000 person-years, respectively.
Optic neuritis is rare among those who initiate anti-TNF therapy and occurs with similar frequency among those with non-biologic DMARD exposure.
shingles; zoster; herpes; biologic therapy; tumor necrosis factor-alpha; rheumatoid arthritis; adverse events; psoriasis
Data about adverse events are needed to optimise telaprevir-based therapy in a broad spectrum of patients.
To investigate adverse events of telaprevir-based therapy in patients with and without advanced fibrosis or cirrhosis in a real-world setting.
Data on 174 hepatitis C-infected patients initiating telaprevir-based therapy at Mount Sinai and Montefiore medical centres were collected. Biopsy data and FIB-4 scores identified patients with advanced fibrosis. Multivariable fully adjusted models were built to assess the effect of advanced fibrosis on specific adverse events and discontinuation of treatment due to an adverse event.
Patients with (n = 71) and without (n = 103) advanced fibrosis were similar in BMI, ribavirin exposure, gender, prior treatment history, haemoglobin and creatinine, but differed in race. Overall, 47% of patients completed treatment and 40% of patients achieved SVR. Treated patients with and without advanced fibrosis or cirrhosis had similar rates of adverse events; advanced fibrosis, however, was independently associated with ano-rectal discomfort (P = 0.03). Three patients decompensated and had advanced fibrosis. The discontinuation of all treatment medications due to an adverse event was significantly associated with older age (P = 0.01), female gender (P = 0.01) and lower platelets (P = 0.03).
Adverse events were common, but were not significantly related to the presence of advanced fibrosis or cirrhosis. More critical monitoring in older and female patients with low platelets throughout treatment may reduce adverse event-related discontinuations.
With an increase in mining depth and production, the intensity and frequency of outburst of coal and gas have a tendency to increase. Estimating the intensity of outbursts of coal and gas plays an important role because of its relation with the risk value. In this paper, we described the semiquantitative relations between major parameters and intensity of outburst based on physical experiments. The results showed increment of geostress simulated by horizontal load (from 1.4, 2.4, 3.2, to 3.4 MPa) or vertical load (from 2, 3, 3.6, to 4 MPa) improved the relative intensity rate (3.763–7.403% and 1.273–7.99%); the increment of porosity (from 1.57, 2.51, 3, to 3.6%) improved the relative intensity rate from 3.8 to 13.8%; the increment of gas pressure (from 0, 0.5, 0.65, 0.72, 1, to 1.5 Mpa) induced the relative intensity rate to decrease from 38.22 to 0%; the increment of water content (from 0, 2, 4, to 8%) caused the relative intensity rate to drop from 5.425 to 0.5%. Furthermore, sensitivity and range analysis evaluates coupled factors affecting the relative intensity. In addition, the distinction with initiation of outburst of coal and gas affected by these parameters is discussed by the relative threshold of gas content rate.
Anti-tumor necrosis factor alpha (anti-TNF) therapies are associated with severe mycobacterial infections in rheumatoid arthritis patients. We developed and validated electronic record search algorithms for these serious infections.
The study used electronic clinical, microbiologic, and pharmacy records from Kaiser Permanente Northern California (KPNC) and the Portland Veterans Affairs Medical Center (PVAMC). We identified suspect tuberculosis and nontuberculous mycobacteria (NTM) cases using inpatient and outpatient diagnostic codes, culture results, and anti-tuberculous medication dispensings. We manually reviewed records to validate our case-finding algorithms.
We identified 64 tuberculosis and 367 NTM potential cases respectively. For tuberculosis, diagnostic code positive predictive value (PPV) was 54% at KPNC and 9% at PVAMC. Adding medication dispensings improved these to 87% and 46% respectively. Positive tuberculosis cultures had a PPV of 100% with sensitivities of 79% (KPNC) and 55% (PVAMC). For NTM, the PPV of diagnostic codes was 91% (KPNC) and 76% (PVAMC). At KPNC, ≥1 positive NTM culture was sensitive (100%) and specific (PPV, 74%) if non-pathogenic species were excluded; at PVAMC, ≥1 positive NTM culture identified 76% of cases with PPV of 41%. Application of the American Thoracic Society NTM microbiology criteria yielded the highest PPV (100% KPNC, 78% PVAMC).
The sensitivity and predictive value of electronic microbiologic data for tuberculosis and NTM infections is generally high, but varies with different facilities or models of care. Unlike NTM, tuberculosis diagnostic codes have poor PPV, and in the absence of laboratory data, should be combined with anti-tuberculous therapy dispensings for pharmacoepidemiologic research.
tuberculosis; nontuberculous mycobacteria; biologic therapy; tumor necrosis factoralpha; electronic medical records; case-finding
Asparagine synthetase (ASNS) is associated with drug resistance in leukaemia, and the function of this enzyme in the context of hepatocellular carcinoma (HCC) is not clear. In this study, the relationship between ASNS expression and clinical outcomes after surgical resection was investigated, and the therapeutic value of ASNS was also evaluated.
The expression of ASNS was evaluated in HCC samples by real-time PCR and immunohistochemistry assays. The correlation between ASNS expression and clinicopathological features was investigated. Potential clinicopathological prognostic factors were examined by univariate and multivariate survival analysis. Asparagine synthetase was overexpressed and knocked down in HCC cell lines to assess the influence of the enzyme on cell proliferation, migration and tumourigenicity. L-asparaginase was used to treat HCC cells with high or low levels of ASNS in vitro and in vivo to examine the therapeutic efficacy.
The expression of ASNS was higher in HCC tumour tissues and was closely correlated with the serum AFP level, tumour size, microscopic vascular invasion, tumour encapsulation, TNM stage and BCLC stage. Patients with low ASNS expression levels had a poor prognosis with respect to overall survival (OS). The multivariate survival analysis indicated that ASNS is an independent prognostic factor for OS. Furthermore, functional studies demonstrated that ASNS significantly inhibits the proliferation, migration and tumourigenicity of HCC cells. The knockdown of ASNS markedly increased sensitivity to L-asparaginase, indicating that cells with different ASNS protein levels have different sensitivities to L-asparaginase.
The expression of ASNS is an independent factor affecting the survival of HCC patients, and low ASNS expression in HCC was correlated with worse surgical outcomes. The ASNS may be a promising therapeutic target for the treatment of HCC.
ASNS; hepatocellular carcinoma; prognosis; predictive biomarker; L-asparaginase
Two experiments were conducted to determine the digestible energy (DE) and metabolizable energy (ME) contents of corn gluten feed (CGF) for finishing pigs and to develop equations predicting the DE and ME content from the chemical composition of the CGF samples, as well as validate the accuracy of the prediction equations. In Exp. 1, ten CGF samples from seven provinces of China were collected and fed to 66 finishing barrows (Duroc×Landrace×Yorkshire) with an initial body weight (BW) of 51.9±5.5 kg. The pigs were assigned to 11 diets comprising one basal diet and 10 CGF test diets with six pigs fed each diet. The basal diet contained corn (76%), dehulled soybean meal (21%) and premix (3%). The ten test diets were formulated by substituting 25% of the corn and dehulled soybean meal with CGF and contained corn (57%), dehulled soybean meal (15.75%), CGF (24.25%) and premix (3%). In Exp. 2, two additional CGF sources were collected as validation samples to test the accuracy of the prediction equations. In this experiment, 18 barrows (Duroc×Landrace×Yorkshire) with an initial BW of 61.1±4.0 kg were randomly allotted to be fed either the basal diet or two CGF containing diets which had a similar composition as used in Exp. 1. The DE and ME of CGF ranged from 10.37 to 12.85 MJ/kg of dry matter (DM) and 9.53 to 12.49 MJ/kg of DM, respectively. Through stepwise regression analysis, several prediction equations of DE and ME were generated. The best fit equations were: DE, MJ/kg of DM = 18.30–0.13 neutral detergent fiber–0.22 ether extract, with R2 = 0.95, residual standard deviation (RSD) = 0.21 and p<0.01; and ME, MJ/kg of DM = 12.82+0.11 Starch–0.26 acid detergent fiber, with R2 = 0.94, RSD = 0.20 and p<0.01. These results indicate that the DE and ME content of CGF varied substantially but the DE and ME for finishing pigs can be accurately predicted from equations based on nutritional analysis.
Corn Gluten Feed; Finishing Pigs; Digestible Energy; Metabolizable Energy; Prediction Equations
Disturbance of endoplasmic reticulum (ER) homeostasis causes ER stress and leads to activation of the unfolded protein response, which reduces the stress and promotes cell survival at the early stage of stress, or triggers cell death and apoptosis when homeostasis is not restored under prolonged ER stress. Here, we report that Cab45S, a member of the CREC family, inhibits ER stress-induced apoptosis. Depletion of Cab45S increases inositol-requiring kinase 1 (IRE1) activity, thus producing more spliced forms of X-box-binding protein 1 mRNA at the early stage of stress and leads to phosphorylation of c-Jun N-terminal kinase, which finally induces apoptosis. Furthermore, we find that Cab45S specifically interacts with 78-kDa glucose-regulated protein/immunoglobulin heavy chain binding protein (GRP78/BiP) on its nucleotide-binding domain. Cab45S enhances GRP78/BiP protein level and stabilizes the interaction of GRP78/BiP with IRE1 to inhibit ER stress-induced IRE1 activation and apoptosis. Together, Cab45S, a novel regulator of GRP78/BiP, suppresses ER stress-induced IRE1 activation and apoptosis by binding to and elevating GRP78/BiP, and has a role in the inhibition of ER stress-induced apoptosis.
Cab45S; GRP78/BiP; IRE1; ER stress; UPR; apoptosis
The apoptosis of glomerular mesangial cells (GMCs) in rat Thy-1 nephritis (Thy-1N), a model of human mesangioproliferative glomerulonephritis (MsPGN), is accompanied by sublytic C5b-9 deposition. However, the mechanism by which sublytic C5b-9 induces GMC apoptosis is unclear. In the present studies, the effect of X-linked inhibitor of apoptosis-associated factor 1 (XAF1) expression on GMC apoptosis and the role of p300 and interferon regulatory factor-1 (IRF-1) in mediating XAF1 gene activation were determined, both in the GMCs induced by sublytic C5b-9 (in vitro) and in the renal tissues of rats with Thy-1N (in vivo). The in vitro studies demonstrated that IRF-1-enhanced XAF1 gene activation and its regulation by p300-mediated IRF-1 acetylation were involved in GMC apoptosis induced by sublytic C5b-9. The element of IRF-1 binding to XAF1 promoter and two acetylated sites of IRF-1 protein were also revealed. In vivo, silence of p300, IRF-1 or XAF1 genes in the renal tissues diminished GMC apoptosis and secondary GMC proliferation as well as urinary protein secretion in Thy-1N rats. Together, these data implicate that sublytic C5b-9 induces the expression of both p300 and IRF-1, as well as p300-dependent IRF-1 acetylation that may contribute to XAF1 gene activation and subsequent GMC apoptosis in Thy-1N rats.
Thy-1 nephritis (Thy-1N); glomerular mesangial cell (GMC) apoptosis; sublytic C5b-9 complexes; p300; interferon regulatory factor-1 (IRF-1)
Coherent twin boundaries (CTBs) in nano-twinned materials could improve crack resistance. However, the role of the CTBs during crack penetration has never been explored at atomic scale. Our in situ observation on nano-twinned Ag under a high resolution transmission electron microscope (HRTEM) reveals the dynamic processes of a crack penetration across the CTBs, which involve alternated crack tip blunting, crack deflection, twinning/detwinning and slip transmission across the CTBs. The alternated blunting processes are related to the emission of different types of dislocations at the crack tip and vary with the distance of the crack tip from the CTBs.
Objective. This study was designed to compare the effects of metformin and repaglinide on the fasting plasma glucose (FPG) and glycated haemoglobin (HbA1c) in newly diagnosed type 2 diabetes in China. Methods. A total of 107 newly diagnosed type 2 diabetic patients (46 women and 61 men) participated in the study. All patients received 3-month treatment of metformin or repaglinide. Fasting blood glucose and HbA1c were determined at baseline and at the end of the 3-month of treatment. Results. FPG and HbA1c decreased in both metformin and repaglinide groups after 3 months treatment (P < 0.01). The reduction of HbA1c was significantly greater in the repaglinide group (P < 0.01). Metformin decreases fasting insulin concentration and HOMA-IR (P < 0.01), and repaglinide improves HOMA-β (P < 0.01). Triglycerides (TG) were reduced in both groups (P < 0.01 in metformin group; P < 0.05 in repaglinide group), but total cholesterol (TC) and low-density lipoprotein (LDL) were decreased only after metformin treatment (P < 0.05). Conclusions. Both repaglinide and metformin were effective in glycaemic control in new onset patients with type 2 diabetes in China. Repaglinide had no effect on insulin sensitivity, but it improved β-cell function.
This study was conducted to examine the atropine eye drop prescription trend for children diagnosed with myopia, and to determine the factors associated with the prescription of atropine eye drops.
This was a population-based cross-sectional study.
This study was conducted using a national representative sample from the National Health Insurance (NHI) claims data. All school children between 4 and 18 years of age who had visited an ophthalmologist and were diagnosed with myopia between 2000 and 2007 were included herein. The main outcome measure was the proportion of subjects who were prescribed atropine eye drops in each year. Logistic regression was used to identify the factors associated with atropine eye drops being prescribed.
The prescription of atropine eye drops for children diagnosed with myopia increased significantly from the school years 2000 (36.9%) to 2007 (49.5%). There was also a shift from prescribing high concentrations (0.5 and 1%) of atropine eye drops to lower concentration ones (0.3, 0.25, and 0.1%) within this period. Atropine eye drops were more frequently prescribed to 9–12-year-old children (OR=1.26–1.42, compared with those 7–8 years old), and to children from families with a high socioeconomic status (OR=1.19–1.25); however, they were less prescribed to those living in mid to low urbanized areas (OR=0.65–0.84).
This study revealed an increasing trend of atropine eye drop prescription for children with myopia in Taiwan. Our study provides eye-care professionals worldwide a reference for the potential integration of atropine eye drops into their clinical practice toward children with myopia.
atropine; myopia; prescription; National Health Insurance claim data
To explore the potential of quantitative analysis of contrast-enhanced ultrasonography (CEUS) in differentiating focal nodular hyperplasia (FNH) from hepatocellular carcinoma (HCC).
34 cases of FNH and 66 cases of HCC (all lesions <5 cm) were studied using CEUS to evaluate enhancement patterns and using analytic software Sonoliver® (Image-Arena™ v.4.0, TomTec Imaging Systems, Munich, Germany) to obtain quantitative features of CEUS in the region of interest. The quantitative features of maximum of intensity (IMAX), rise slope (RS), rise time (RT) and time to peak (TTP) were compared between the two groups and applied to further characterise both FNH and HCC with hypoenhancing patterns in the late phase on CEUS.
The sensitivity and specificity of CEUS for diagnosis of FNH were 67.6% and 93.9%, respectively. For quantitative analysis, IMAX and RS in FNHs were significantly higher than those in HCCs (p<0.05), while RT and TTP in FNHs were significantly shorter (p<0.05). Both the 11 FNHs and 62 HCCs with hypo-enhancing patterns in the late phase were further characterised with their quantitative features, and the sensitivity and specificity of IMAX for diagnosis of FNH were 90.9% and 43.5%, RS 81.8% and 80.6%, RT 90.9% and 71.0%, and TTP 90.9% and 71.0%, respectively.
The quantitative features of CEUS in FNH and HCC were significantly different, and they could further differentiate FNH from HCC following conventional CEUS.
Advances in knowledge:
Our findings suggest that quantitative analysis of CEUS can improve the accuracy of differentiating FNH from HCC.
The IκB kinase (IKK)/NF-κB pathway has been shown to be a major regulator in cell survival. However, the mechanisms through which IKK mediates cell death are not clear. In this study, we showed that IKK-β contributed to hydrogen peroxide (H2O2)-induced cell death independent of the NF-κB pathway. Our results demonstrated that the pro-death function of IKK-β under oxidative stress was mediated by p85 S6K1 (S6 kinase 1), but not p70 S6K1 through a rapamycin-insensitive and mammalian target of rapamycin complex 1 kinase-independent mechanism. We found that IKK-β associated with p85, but not p70 S6K1, which was required for H2O2-induced activation of p85 S6K1. IKK-β and p85 S6K1 contributed to H2O2-induced phosphorylation of Mdm2 (S166) and p53 accumulation. p85 S6K1 is critical for IKK-β-mediated cell death. Thus, these findings established a novel oxidative stress-responsive pathway that involves IKK-β, p85 S6K1 and Mdm2, which is response for H2O2-induced cell death. Our results have important implications for IKK-β and p85 S6K1 as potential targets for the prevention of diseases involved in oxidative stress-induced aberrant cell death.
IKK-β; hydrogen peroxide; S6K1; mammalian target of rapamycin
GATA1 mutations are tightly associated with transient myeloproliferative disorder (TMD) and acute megakaryoblstic leukemia (AMKL) in children with Down syndrome. Numerous genes are altered in GATA-1-deficient megakaryocytes, which may contribute to the hyperproliferation and abnormal terminal differentiation of these malignant cells. In this study, we demonstrate that Pstpip2 is a GATA-1-repressed gene that controls megakaryopoiesis. Ectopic expression of PSTPIP2 impaired megakaryocytic differentiation as evidenced by a decrease of CD41 expression and reduced DNA content in K562 cells. PSTPIP2 overexpression also caused enhanced activation of Src family kinases and subsequently reduced ERK phosphorylation. Consistently, PSTPIP2 knockdown showed the opposite effect on differentiation and signaling. Moreover, the W232A mutant of PSTPIP2, defective in its interaction with PEST family phosphatases that recruit c-Src terminal kinase (CSK) to suppress Src family kinases, failed to inhibit differentiation and lost its ability to enhance Src family kinases or reduce ERK phosphorylation. In fact, the W232A mutant of PSTPIP2 promoted megakaryocyte differentiation. These observations suggest that PSTPIP2 recruiting PEST phosphatases somehow blocked CSK activity and led to enhanced activation of Src family kinases and reduced ERK phosphorylation, which ultimately repressed megakaryocyte differentiation. Supporting this idea, PSTPIP2 interacted with LYN and the expression of a dominant negative LYN (LYN DN) overwhelmed the inhibitory effect of PSTPIP2 on differentiation and ERK signaling. In addition, a constitutively active LYN (LYN CA) normalized the enhanced megakaryocyte differentiation and repressed ERK signaling in PSTPIP2 knockdown cells. Finally, we found that PSTPIP2 repressed ERK signaling, differentiation, and proliferation and verified that PSTPIP2 upregulation repressed megakaryocyte development in primary mouse bone marrow cells. Our study thus reveals a novel mechanism by which dysregulation of PSTPIP2 due to GATA-1 deficiency may contribute to abnormal megakaryocyte proliferation and differentiation in pathogenesis of related diseases.
TPO signaling; GATA-1; PSTPIP2; megakaryopoiesis; LYN
R-(−)-gossypol acetic acid (AT-101) is a natural cottonseed product that exhibits anticancer activity. However, the molecular mechanism behind the antileukemic activity of AT-101 has not been well characterized. In this study, we investigated how AT-101 induces apoptosis in human leukemia cells. Exposure to AT-101 significantly increased apoptosis in both human leukemia cell lines and primary human leukemia cells. This increase was accompanied by the activation of caspases, cytochrome c release, Bcl2-associated X protein (Bax) translocation, myeloid cell leukemia-1 (Mcl-1) downregulation, Bcl-2-associated death promoter (Bad) dephosphorylation, Akt inactivation, and RhoA/Rho-associated coiled-coil containing protein kinase 1/phosphatase and tensin homolog (RhoA/ROCK1/PTEN) activation. RhoA, rather than caspase-3 cleavage, mediated the cleavage/activation of ROCK1 that AT-101 induced. Inhibiting RhoA and ROCK1 activation by C3 exoenzyme (C3) and Y27632, respectively, attenuated the ROCK1 cleavage/activation, PTEN activity, Akt inactivation, Mcl-1 downregulation, Bad dephosphorylation, and apoptosis mediated by AT-101. Knocking down ROCK1 expression using a ROCK1-specific siRNA also significantly abrogated AT-101-mediated apoptosis. Constitutively active Akt prevented the AT-101-induced Mcl-1 downregulation, Bad dephosphorylation, and apoptosis. Conversely, AT-101 lethality was potentiated by the phosphatidylinositol 3-kinase inhibitor LY294002. In vivo, the tumor growth inhibition caused by AT-101 was also associated with RhoA/ROCK1/PTEN activation and Akt inactivation in a mouse leukemia xenograft model. Collectively, these findings suggest that AT-101 may preferentially induce apoptosis in leukemia cells by interrupting the RhoA/ROCK1/PTEN pathway, leading to Akt inactivation, Mcl-1 downregulation, Bad dephosphorylation, and Bax translocation, which culminate in mitochondrial injury and apoptosis.
AT-101; RhoA/ROCK1/PTEN signaling; apoptosis; leukemia; xenograft