Congxin Dai

Inhibition of PI3K/AKT/mTOR Pathway Enhances Temozolomide-Induced Cytotoxicity in Pituitary Adenoma Cell Lines in Vitro and Xenografted Pituitary Adenoma in Female Nude Mice

Invasive pituitary adenomas (PAs) are often refractory to standard therapy and salvage treatment with temozolomide (TMZ). Hyperactivation of the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway contributes to chemotherapy resistance in many cancers. XL765, a novel dual-PI3K/mTOR inhibitor, has recently shown its efficacy as a monotherapy and in combination with conventional therapeutics in many cancers. The hyperactive PI3K/AKT/mTOR pathway frequently occurs in invasive PAs. In this study, we investigated whether XL765 sensitizes PA cells to TMZ in vitro and in vivo. Experiments were carried out to evaluate the effect of XL765 and TMZ alone or in combination on cell proliferation and apoptosis of PA cell lines (αT3-1, GH3, and MMQ) in vitro as well as the tumor growth and serum GH and prolactin secretions in a GH3 xenograft tumor model of female nude mice. XL765 and TMZ synergistically inhibited the growth of PA cell lines and induced apoptosis. Combination of XL765 and TMZ synergistically inhibited tumor growth, decreased serum GH and prolactin levels, and reduced the sacrifice rate of GH3 xenograft tumor models without increased systemic side effects. In addition, XL765 in combination with TMZ dramatically decreased phosphorylation of AKT and mTOR as well as the expression of Bcl-2. The increased expression of cleaved poly (ADP-ribose) polymerase and Bcl-2-associated X protein along with elevated caspase-3/7 activity were also observed in the combination group. Therefore, dual inhibitors of PI3K and mTOR may enhance alkylating agent-mediated cytotoxicity and provide a novel regimen in the treatment of invasive PAs.

Anti-TNF-α therapy for patients with sepsis: a systematic meta-analysis.

In humans, the role of anti‐tumour necrosis factor (TNF)‐α therapy in severe sepsis and septic shock is debatable. The aim of this meta‐analysis was to determine the efficacy of anti‐TNF‐α therapies against placebo in patients with severe sepsis or septic shock.

The Downregulation of MicroRNA-146a Modulates TGF-β Signaling Pathways Activity in Glioblastoma.

Transforming growth factor-β (TGF-β) is considered to be one of the main factors responsible for glioblastoma tumorigenesis. MicroRNAs have recently been shown to regulate cell proliferation, differentiation, and apoptosis. However, the involvement of miRNA-146a in TGF-β1-induced glioblastoma development remains largely unknown. Here, miRNA-164a transfection was used to overexpress miRNA-164a in U87, and then real-time quantitative PCR and Western blot were applied to detect the gene transcription and protein expression. In addition, MTT and wound healing assay were also used to observe cell proliferation and migration. Our data revealed that miRNA-146a was downregulated by TGF-β1 treatment, but upregulated by miRNA-164a transfection. MiRNA-146a overexpression significantly reduced SMAD4 protein expression instead of p-SMAD2. Besides, miRNA-146a overexpression also decreased the messenger RNA (mRNA) and protein expression of epidermal growth factor receptor (EGFR) and MMP9 as well as the p-ERK1/2 level. Furthermore, the upregulation of miRNA-146a suppressed TGF-β1-mediated U87 proliferation and migration. These results demonstrate that miRNA-146a acts as a novel regulator to modulate the activity and transduction of TGF-β signaling pathways in glioblastoma, and the downregulation of miRNA-146a is required for overexpression of EGFR and MMP9, which can be considered an efficiently therapeutic target and a better understanding of glioblastoma pathogenesis.

Pyrimethamine sensitizes pituitary adenomas cells to temozolomide through cathepsin B-dependent and caspase-dependent apoptotic pathways.

Invasive pituitary adenomas (PAs) are generally refractory to conventional therapy and salvage treatment with temozolomide (TMZ). In addition to antiprotozoan effects, pyrimethamine (PYR) has recently shown its strong antitumor activity as an antineoplastic agent or in combination with TMZ in metastatic melanoma cells. In this study, the effects of TMZ, PYR or TMZ/PYR combination on rat/mouse PA cell lines αT3‐1, GH3, MMQ and ATt‐20 as well as GH3 xenograft tumor model were evaluated. TMZ/PYR combination synergistically inhibited proliferation, invasion and induced apoptosis of these PA cell lines in vitro. Strikingly, combination treatment with TMZ and PYR produced synergistic antitumor activity and enhanced the survival rate of GH3 xenograft tumor models without increasing systemic side effects. In addition, TMZ/PYR induced cell cycle arrest, increased DNA damage, upregulated the expression of cathepsin B, BAX, cleaved PARP and phosphorylated histone H2AX as well as elevated caspase3/7, 8 and 9 activities. The decreased expression of Bcl‐2, MMP‐2 and MMP‐9 alone with cytochrome c release from mitochondria into the cytosol was also observed in the TMZ/PYR combination group. The increase in cell apoptosis due to combination with PYR was rescued by leucovorin. These data suggest that PYR may enhance the efficacy of TMZ via triggering both cathepsin B‐dependent and caspase‐dependent apoptotic pathways. Therefore, combination of PYR and TMZ may provide a novel regimen for invasive PAs refractory to standard therapy and TMZ.

Screening for AIP gene mutations in a Han Chinese pituitary adenoma cohort followed by LOH analysis

OBJECTIVEnThe aryl hydrocarbon receptor interacting protein gene (AIP) is associated with pituitary adenoma (PA). AIP has not been sequenced in East Asian PA populations, so we performed this study in a Han Chinese cohort.nnnDESIGNnOur study included six familial PA pedigrees comprising 16 patients and 27 unaffected relatives, as well as 216 sporadic PA (SPA) patients and 100 unrelated healthy controls.nnnMETHODSnAIP sequencing was carried out on genomic DNA isolated from blood samples. Multiplex ligation-dependent probe amplification and microsatellite marker analyses on DNA from the paired tumor tissues were performed for loss of heterozygosity analysis.nnnRESULTSnWe identified three common and four rare single nucleotide polymorphisms (SNPs), one intron insertion, one novel synonymous variant, four novel missense variants, and a reported nonsense mutation in three familial isolated PA (FIPA) cases from the same family. Large genetic deletions were not observed in the germline but were seen in the sporadic tumor DNA from three missense variant carriers. The prevalence of AIP pathogenic variants in PA patients here was low (3.88%), but was higher in somatotropinoma patients (9.30%), especially in young adults (≤30 years) and pediatric (≥18 years) paients (17.24% and 25.00% respectively). All AIP variant patients suffered from macroadenomas. However, the AIP mutation rate in FIPA families was low in this cohort (16.67%, 1/6 families).nnnCONCLUSIONnAIP gene mutation may not be frequent in FIPA or SPA from the Han Chinese population. AIP sequencing and long-term follow-up investigations should be performed for young patients with large PAs and their families with PA predisposition.

Differential expression of folate receptor alpha in pituitary adenomas and its relationship to tumor behavior.

BACKGROUNDnFolate receptor alpha (FRα) plays a pivotal role in the tumorigenesis of some malignant tumors, but its role and clinical significance in pituitary adenomas remain unclear.nnnOBJECTIVEnTo identify a possible biomarker for the diagnosis of nonfunctional pituitary adenomas (NFAs) that could also be used to assess tumor behavior.nnnMETHODSnSporadic pituitary tumor specimens (n = 76) and normal pituitary glands (n = 7) were examined. FRα protein and mRNA expression were quantified by immunohistochemistry and quantitative reverse transcriptase polymerase chain reaction, respectively. We verified the differential expression of FRα in pituitary adenomas and evaluated the associations of FRα expression with Ki-67 labeling index (LI) and clinicopathologic characteristics of NFAs. Statistical significance was determined by using the Student t test or one-way analysis of variance.nnnRESULTSnFRα mRNA and protein was uniquely overexpressed in NF (immunohistochemically positive) and NF (immunohistochemically negative) adenomas but not in functional adenomas (adrenocorticotropic hormone, growth hormone, and prolactin) or normal adenohypophysial tissues (P < .001). The expression of FRα was positively correlated with tumor invasiveness, size and Ki-67 LI in NFAs.nnnCONCLUSIONnFRα may play an important role in the development and progression of NFAs. Therefore, FRα may be useful as a molecular biomarker for the diagnosis of NFAs and assessment of tumor invasiveness.

The association of CXCR4 expression with prognosis and clinicopathological indicators in colorectal carcinoma patients: a meta-analysis.

The clinical relevance of expression of chemokine receptor 4 (CXCR4) in colorectal carcinoma (CRC) remains controversial; our aim was to identify the precise relationship of CXCR4 to prognosis and clinicopathological features.

Antiproliferative, Antiinvasive, and Proapoptotic Activity of Folate Receptor α-Targeted Liposomal Doxorubicin in Nonfunctional Pituitary Adenoma Cells

There is an urgent need for novel therapeutic strategies for the treatment of nonfunctional pituitary adenomas (NFPAs), especially those that are invasive. The folate receptor (FR)α is overexpressed in several cancers, including NFPA. The aim of this study was to determine the efficacy of FRα-targeted liposomes loaded with doxorubicin (F-L-DOX) in the treatment of NFPA. We evaluated targeting, cytotoxicity, antiinvasive, and proapoptotic activity of F-L-DOX in 25 primary cell lines derived from patients with NFPAs. We found that these liposomes effectively targeted NFPA cells through FRα and that endocytosis of the liposomes was blocked by 1mM free folic acid. F-L-DOX inhibited proliferation of NFPA cells and promoted apoptosis through activation of caspase-8, caspase-9, and caspase-3/7 more effectively than L-DOX. Furthermore, F-L-DOX also exerted greater antiinvasive ability in NFPA cells than L-DOX through suppression of the secretion of matrix metalloproteinase-2 and matrix metalloproteinase-9. Addition of 1mM free folic acid significantly reduced the pleotropic effects of F-L-DOX in NFPA cells, suggesting that FRα plays a critical role in mediating the antitumor effect of F-L-DOX. Our findings warrant further investigation of F-L-DOX as an alternative therapeutic strategy for the treatment of NFPAs that express FRα.

Effect of temozolomide on cell viability in gonadotroph adenoma cell lines

Invasive pituitary adenomas are usually refractory to routine neurosurgery, radiosurgery or medications, and alternative therapies are needed. The effects of temozolomide (TMZ) on the inhibition of gonadotroph adenoma cell viability and hormone secretion were evaluated. Cell viability and IC50 values were evaluated after αT3-1 cells were treated with TMZ (31.25-1000 µM) or vehicle for 0-72 h. Cell cycle changes and the extent of apoptosis were detected using flow cytometry, TUNEL and TEM. The molecular mechanism of TMZ action was investigated by the Caspase-Glo® assay and immunoblotting. Gonadotropin secretion was assessed using an immunoassay system. TMZ dose- and time-dependently suppressed cell proliferation (P<0.01 vs. control, 250 µM, 24xa0h) and induced S-phase accumulation and G2/M-phase arrest (P<0.05 vs. control, 250 µM, 24 h). Early apoptotic cells increased following a 24-h TMZ incubation (P<0.001 vs. control, 250 µM), consistent with TEM and TUNEL detection that exhibited morphological features of apoptosis. TMZ (250xa0µM) increased the level of caspase-3/7 by 6-fold, caspase-9 by 7-fold and caspase-8 by 3-fold after a 24-h incubation, while it attenuated Bcl-2 expression (P<0.001 vs. control) and raised the proteolysis of PARP. Both FSH and LH levels were significantly decreased by TMZ (P<0.01 vs. control, 250 µM, 24xa0h). TMZ inhibited cell proliferation and hormone secretion, and induced cell cycle arrest and apoptotic cell death in gonadotroph adenoma cells via both death receptor and mitochondrial pathways, suggesting that it may represent a useful medical management strategy of invasive gonadotroph adenomas.

O-6-Methylguanine-DNA methyltransferase expression is associated with pituitary adenoma tumor recurrence: a systematic meta-analysis

O-6-methylguanine-DNA methyltransferase (MGMT) reportedly counteracts the cytotoxic effects of the alkylating agent temozolomide. MGMT expression is often low in aggressive pituitary adenomas (PAs) and recurrent PAs. However, because these associations are controversial, we performed this meta-analysis to clarify the involvement of MGMT in the prognosis and clinicopathology of PA. We searched for relevant studies in electronic databases (MEDLINE, the Cochrane Library Database, EMBASE, CINAHL, Web of Science and the Chinese Biomedical Database (CBD)) and calculated/pooled the odds ratios (ORs) or standard mean differences (SMDs) with 95% confidence intervals (95% CIs). Eleven case-control studies with a total of 454 PA patients were included. Our meta-analysis revealed that lower expression of MGMT was associated with PA recurrence (OR=2.09, 95% CI=1.09–4.02; p=0.026). On the other hand, MGMT expression was not associated with PA invasiveness (OR=1.112, 95% CI=0.706–1.753; p=0.646), Unexpectedly, MGMT expression could not be used to distinguish functional from non-functional PA patients (OR=1.766, 95% CI=0.938–3.324; p=0.078). The MGMT expression was not found to be related to other clinicopathological indicators of PA including age, gender or tumor size. No publication bias was detected in this meta-analysis (p>0.05). This meta-analysis suggests that MGMT expression may be associated with PA tumor recurrence, but not be related to invasiveness or other clinicopathological indicators. Thus, detection of MGMT expression may facilitate outcome prediction and guide clinical therapy for PA patients.