Reliable high-throughput approach for screening of engineered constitutive promoters in the yeast Pichia pastoris

AIMS

To develop a reliable and sensitive high-throughput approach for the screening of engineered constitutive promoters in the yeast Pichia pastoris.

METHODS AND RESULTS

The yeast-enhanced green fluorescent protein (yEGFP) was used as the reporter to monitor the promoter strength. After eliminating the interfering components (yeast extract and tryptone) with fluorescence signal from the medium, a high-throughput screening approach was established and optimized to obtain a low standard deviation of cell density (6.9%) and fluorescence (7.4%) in 48-deep-well microplates. Then, 300 clones containing GAP promoter (P(GAP)) variants were screened, exhibiting a wide range in fluorescent intensity from about 8% to 218% of that obtained with P(GAP). Six representative clones with unique promoter sequence were picked for further characterization. A good correlation between yEGFP fluorescence in microplates and shake flasks was observed. Furthermore, the high correlation between fluorescence and transcript levels confirmed that expression was transcriptionally controlled.

CONCLUSIONS

We developed a reliable high-throughput screening approach that can be used to select engineered constitutive promoters of varying strengths.

SIGNIFICANCE AND IMPACT OF THE STUDY

This approach is expected to accelerate the selection of constitutive promoters in P. pastoris and can also be applied for the screening of other constitutive expression clones.

Erythromycin inhibited glycinergic inputs to gastric vagal motoneurons in brainstem slices of newborn rats

BACKGROUND

Motilin has been known to stimulate the motility of digestive organs peripherally via activation of motilin receptors located at gastrointestinal (GI) cholinergic nerve endings and/or smooth muscle cells. Recent studies have indicated that motilin may also promote GI motility via actions in the central nervous system; however the sites of action and the mechanisms are not clear yet. The present study aimed to test the hypothesis that motilin receptor agonist erythromycin alters the synaptic inputs of preganglionic gastric vagal motoneurons (GVMs) located in the dorsal motor nucleus of the vagus (DMV).

METHODS

Gastric vagal motoneurons were retrogradely labeled by fluorescent tracer from the stomach wall of newborn rats. Fluorescently labeled GVMs in DMV were recorded using whole-cell patch-clamp in brainstem slices and the effects of motilin receptor agonist erythromycin on the synaptic inputs were examined.

KEY RESULTS

Erythromycin (100 nmol L(-1), 1 μmol L(-1), 10 μmol L(-1)) significantly inhibited the frequency of glycinergic spontaneous inhibitory postsynaptic currents (sIPSCs) of GVMs and significantly inhibited the amplitude at the concentration of 10 μmol L(-1). These responses were prevented by GM-109, a selective motilin receptor antagonist. In the pre-existence of tetradotoxin (TTX, 1 μmol L(-1)), erythromycin (10 μmol L(-1)) caused significant decreases of the glycinergic miniature inhibitory postsynaptic currents (mIPSCs), in both the frequency and the amplitude. However, erythromycin (10 μmol L(-1)) didn't cause significant changes of the GABAergic sIPSCs.

CONCLUSIONS & INFERENCES

Erythromycin selectively inhibits the glycinergic inputs of GVMs.

Cisplatin induces programmed death-1-ligand 1(PD-L1) over-expression in hepatoma H22 cells via Erk /MAPK signaling pathway

Cisplatin has been widely used in cancer treatment. However, the prognosis of the cancer patients following chemotherapy has not been substantially improved and several different mechanisms could be involved. Clinically alternative strategies such as immunotherapy and their combinations with chemotherapy have being used. Cancer immunoresistance and immune escape are major obstacles in chemotherapy. However, the effects of cisplatin on the immune responses of cancer cells are not clear. In the present studies, we investigate the expression of immunoresistance moleculor PD-L1 (the negative regulator programmed death-1-ligand 1) on cisplatin-induced hepatoma H22 cells, which can interact with PD-1 on T cells to mediate cancer immunoresistance. Hepatoma H22 cells were treated with cisplatin in vivo or in vitro to analysis the expression of PD-L1 by flow cytometry (FACS). Erk1/Erk2 phosphorylation expressions were examined by western blotting. We demonstrated that cisplatin was able to induce H22 cell apoptosis and when the concentration less than IC50 cisplatin could up-regulate PD-L1 expression in hepatoma H22 cells. The optimal concentration of cisplatin for the highest expression of PD-L1 was 0.5 μg/ml in vitro. Meanwhile, cisplatin could induce the phosphorylation of Erk1/2.The lack of effect during treatment with a specific MAPK pathway inhibitor PD98059, demonstrated that cisplatin-induced PD-L1 expression is dependent of Erk1/2 phosphorylation. Our studies reveal a potential link between chemotherapy and cancer immunoresistance. PD-L1 and its signaling pathway appear to be a potential therapeutic target for the cisplatin treatment of hepatoma.

RKTG inhibits angiogenesis by suppressing MAPK-mediated autocrine VEGF signaling and is downregulated in clear-cell renal cell carcinoma

Vascular endothelial growth factors (VEGFs) are crucial regulators of angiogenesis and vasculogenesis. The autocrine VEGF signaling is required for maintaining the homeostasis of vasculature. Dysregulation of angiogenesis is implicated in the development of many human cancers, especially in clear-cell renal cell carcinoma (ccRCC), a highly vascularized tumor. Meanwhile, antiangiogenesis has become a mainstay in the treatment of human cancers. In this study, we analyzed the functional roles of RKTG (Raf Kinase Trapping to Golgi), a negative regulator of mitogen-activated protein kinase (Raf/MEK/ERK) signaling, by sequestration of Raf kinase to the Golgi apparatus, in angiogenesis and ccRCC. Through a series of in vitro and in vivo experiments, we found that RKTG has a negative effect on cell proliferation, migration, sprouting and angiogenesis of endothelial cells. RKTG, by suppressing mitogen-activated protein kinase signaling, negatively regulates the transactivation activity of hypoxia-inducible factor 1α (HIF-1α) by inhibiting formation of HIF-1α/p300 complex and suppressing VEGF transcription, thereby reducing hypoxia-induced VEGF production. The expression level of RKTG is significantly downregulated in clinical ccRCC tumor samples, with an inverse correlation with VEGF expression level. These results highlight the functional roles of RKTG and its regulated Raf/ERK/MEK signaling cascade in angiogenesis and autocrine VEGF signaling. In addition, this study indicates that RKTG is likely implicated in the development of ccRCC through its regulation on angiogenesis.

Detection of PCR products using self-reporting duplex mutation primers

A novel oligonucleotide probe, with duplex mutation primers, which comprised a normal reverse primer labelled with a fluorophore at its 5'-end and a single-base mismatched complementary oligonucleotide labelled with a quencher at its 3'-end, was designed. Its application in the detection of hepatitis B virus (HBV) DNA of serum was investigated; results were compared with those obtained using a commercial TaqMan kit. There was a good linear correlation in the range of 10(2) approximately 10(7) copies/ml (r(2) = 0.999) with the method. Intra-experimental coefficients of variation (CVs) were 0.70% approximately 7.80%, and inter-experimental CVs were 0.78% approximately 9.02%, respectively. There was no significant difference of HBV genome number tested by the two methods (p<0.05) in 132 hepatitis B patients; HBV DNA was not detected in any serum samples of 20 healthy volunteers by the two methods.

Waist circumference, body mass index and waist to hip ratio for prediction of the metabolic syndrome in Chinese

BACKGROUND AND AIMS

To explore the ability of waist circumference (WC), body mass index (BMI) and waist to hip ratio (WHR) to predict two or more non-adipose components of the metabolic syndrome (MetS) among individuals aged 18-85 in North China.

METHODS AND RESULTS

This study is a cluster sample survey of 101,510 individuals, complete data are 75,788 subjects, 59,874 males and 15,914 females. Their ages were 51.9+/-12.7 years (males) and 48.7+/-11.5 years (females). Receiver operating characteristic (ROC) analysis was used to examine discrimination and find optimal cut off values of WC, BMI and WHR to predict two or more non-adipose components of MetS. The area under the ROC curve (AURC) for WC (0.694) and BMI (0.692) in females showed no difference. In males BMI (0.657) had a better discrimination than WC (0.634). WHR was weaker in both sexes. The optimal cut off value of WC in males (86.5 cm) was higher than in females (82.1cm); and that of BMI was about 24 kg/m(2) in both genders. The optimal cut off values of WC, BMI, and WHR, increased with age in both sexes.

CONCLUSIONS

BMI and WC are more useful than WHR for predicting two or more non-adipose components of MetS. Cut off values for WC in males, and those of BMI and WHR in both sexes are lower than that in present MetS criteria; WC in females is slightly higher. Cut off values of WC, BMI and WHR were increased with age in the Chinese.

Therapeutic vaccination against advanced pancreatic cancer by autologous dendritic cells pulsed with a MUC1 peptide: Preclinical results of a clinical phase I trial

e15652

Background: Pancreatic ductal adenocarcinoma has a particularly poor prognosis. Therefore, novel therapeutic strategies such as immunotherapy are required. The aim of the present phase I study was to evaluate the safety, immune responses and clinical activity of a vaccine based on autologous dendritic cells (DC) pulsed with a specific MUC1 peptide in advanced pancreatic cancer patients. Methods: Five patients who had pancreatic cancer ductal adenocarcinoma expressing MUC1 in stage of III/IV were enrolled to the clinical trial. Patients underwent leukapheresis to generate dendritic cells by culture in vitro with granulocyte macrophage colony-stimulating factor and interleukin-4 for 5 days. Dendritic cells were then pulsed overnight with MUC1 peptide (GVTSAPDTRPAPGSTAPPAH) and harvested for vaccination. Dendritic cells (3×106-6×106) were injected intradermally every 2 weeks for 3–4 times. Results: All patients remained with progressive disease. Four patients developed strong T-cell IFN-γ and Granzyme B Elispot responses to the vaccine. Most interestingly, the patient who was treated with the highest number of DC(6×106) had more number of CTL than other patients and showed delayed-type hypersensitivity responses at injection sites and this patient stopped application of the analgetics. Another patient with relapsed pancreatic cancer who had finished the 4 times of vaccination and then followed 6 times of chemotherapy with Gemcitabine had a surprisingly long term of survival of 12 month. No evidence of significant treatment related toxicity or auto-immunity was observed. Conclusions: This study showed the safety and clinical response of MUC1 peptide-pulsed dendritic cell therapy for patients with advanced pancreatic cancer. It confirms the capability of this DC vaccine to stimulate an immune response in patients with pancreatic cancer even in the presence of a large tumor burden. Dendritic cell therapy is recommended for further clinical studies in pancreatic cancer patients.

No significant financial relationships to disclose.

A novel recombinant tandem repeat DNA vaccine targeting at MUC1

3066

Background: Tandem repeat (TR) is the key epitope of mucin 1 (MUC1) for inducing cytotoxic T lymphocytes (CTL) to kill the tumor cells specifically. A novel recombinant TR DNA vaccine was constructed to study its induced immune responses. Methods: A recombinant human TR (rhTR) gene encoding a single TR polypeptide of MUC1 was synthesized and cloned into the multiple cloning sites of plasmid pcDNA3.1/Myc-his (+) A to construct the recombinant plasmid pcDNA3.1-TR/Myc-his (+) A (pTR plasmid). Expression of pTR plasmid was confirmed by transfection assay and Western blot analysis. C57BL/6 (H-2b) mice were immunized with pTR plasmid (n=15) by tibial muscle injection. Mice inoculated with the empty vector (EV group, n=15) and 0.9% NaCl solution (NS group, n=15) were used as vector and blank control respectively. Four weeks later, all mice were immunized again. Specific antibody detection and cytotoxic assay were used to evaluate the vaccine-induced TR specific immune responses. Results: DNA sequencing confirmed that the pTR plasmid was exactly constructed. Transfection assay and Western blot analysis found that the transfected COS7 cells expressed TR polypeptide of MUC1 48 hours after transfection. Cytotoxic assay showed that immunization with pTR plasmid into C57BL/6 mice resulted in more efficient induction of CTL specific cytolysis against TR polypeptide than that of EV group and NS group (p<0.01). Vaccine immunized mice had a higher equivalent concentration of anti-TR specific antibodies (2324μg/ml±238μg/ml) than that of EV group (1896μg/ml±533μg/ml, p<0.01) and NS group (1736μg/ml±142μg/ml, p<0.01). Conclusions: The novel recombinant TR DNA vaccine targeting at MUC1 was exactly constructed, immunization with which could induce TR specific CTL response and antibodies response in mice.

No significant financial relationships to disclose.

Preoperative hepatic and regional arterial chemotherapy in the prevention of liver metastasis after colorectal cancer surgery

4090

Background: To investigate whether preoperative hepatic and regional arterial chemotherapy are able to prevent liver metastasis and improve overall survival in patients receiving curative colorectal cancer resection. Methods: Patients with Stage II or Stage III colorectal cancer (CRC) were randomly assigned to receive preoperative hepatic and regional arterial chemotherapy (PHRAC group, n=256) or surgery alone (control group, n=253). The primary endpoint was disease-free survival, whereas the secondary endpoints included liver metastasis-free survival and overall survival. Results: There were no significant differences in overall morbidity between PHRAC and Control groups. During the follow-up period (median, 42 months), the median liver metastasis time for patients with stage III CRC was significantly longer in the PHRAC group (16±3 months v.s. 8±1 months, P=0.01). In stage III patients, there was also significant difference between the two groups with regard to the incidence of liver metastasis (18.9% vs 27.3%, P=0.01), 5-year disease-free survival (70.2% vs 52.0%, P=0.0076), 5-year overall survival (80.3% vs 69.5%, P=0.020) and the median survival time (40.1± 4.6 months vs 36.3 ± 3.2 months, P=0.03). In the PHRAC arm, the risk ratio of recurrence was 0.63 (95% CI, 0.51–0.79, P=0.0001), of death was 0.50(95% CI, 0.32–0.67; P=0.005), and of liver metastasis was 0.70 (95% CI, 0.52–0.86; p=0.01). In contrast, PHRAC seemed to be no benefit for stage II patients. Toxicities, such as hepatic toxicity and leucocyte decreasing, were mild and could be cured with medicine. Conclusions: Preoperative hepatic and regional arterial chemotherapy, in combination with surgical resection, could be able to reduce and delay the occurrence of liver metastasis and therefore improve survival rate in patients with stage III colorectal cancer.

No significant financial relationships to disclose.

A phase I study of CNTO328, an anti-interleukin (IL)-6 monoclonal antibody combined with docetaxel in subjects with metastatic castration-resistant prostate cancer (CRPC)

5063

Background: IL-6 is a potential mediator of prostate cancer morbidity and mortality and may protect prostate cancer cells from chemotherapy-induced apoptosis. CNTO328, a chimeric anti-IL-6 antibody, has been shown to inhibit prostate tumor growth in xenograft mouse models. Methods: Chemotherapy-naïve patients with metastatic CRPC were administered CNTO328 in combination with T (75 mg/m2 q3w) in 3 dose-escalation cohorts (6 mg/kg q2w, and 9 and 12 mg/kg q3w) following an initial run-in cycle of T alone to examine the effect of CNTO328 on T pharmacokinetics (PK). Safety was evaluated prior to each dose escalation. Prostate specific antigen (PSA), radiological response, and C-reactive protein (CRP), the best-known surrogate of serum IL-6 bioactivity, were also assessed. Results: This study is fully enrolled December 2008 with 38 patients. 36 patients with KPS ≥70, median age 66 (range 43–82) received 6 (median) cycles of T (range 1–37). 32 patients received at least one dose of CNTO328 in combination with T and are evaluable. Baseline patient characteristics included: median PSA of 59 ng/mL (range 12–1430) and median CRP was 3.85 mg/L (range <1 to 91.3). One DLT was observed in each cohort (grade 4 neutropenic infection, grade 3 syncope and dehydration, grade 3 GI bleeding), though MTD for the combination was not reached. Most frequent ≥grade 3 adverse events (AE) were neutropenia (69%); leukopenia (63%); lymphopenia (31%); dyspnea (19%); fatigue (16%). One patient died due to AE (sepsis) reported as possible related to T and unlikely related to CNTO328 by investigator. Preliminary data show CNTO328 does not appear to have a major effect on T PK. Preliminary efficacy data is shown in the table . Ongoing evaluation indicates 3/12 partial responses in patients with measurable disease reported thus far. Conclusions: CNTO328 with T is well tolerated and demonstrates biological and clinical activity in CRPC that warrants further study.

[Table: see text]

[Table: see text]

Is the relationship between syndromes of depression and dementia temporal? The MRC-ALPHA and Hefei-China studies

BACKGROUND

Recent studies have shown a temporal association between depressive symptoms and cognitive decline. However, the relationship between syndromes of depression and dementia is unknown.

METHOD

A total of 1736 people aged > or = 65 years in China and 5222 older people in the UK were interviewed using the Geriatric Mental State Examination (GMS) and reinterviewed at follow-up. Five levels of syndromes of depression and dementia were diagnosed using the Automated Geriatric Examination for Computer Assisted Taxonomy (AGECAT).

RESULTS

Although there were fewer depressive syndromes in Chinese than British participants, both populations showed a similarly high level of syndromes of dementia (organic disorder) (20% for women, 14% for men). There was a significant cross-sectional correlation between syndrome levels of depression and dementia (correlation coefficients: 0.141-0.248 for Chinese, 0.168-0.248 for British). This was maintained for different age, gender and people with and without cardiovascular disease (CVD). The relationship between syndromes of baseline depression and follow-up dementia was less substantial: the correlation coefficient was 0.075 [95% confidence interval (CI) 0.021-0.128] for the Chinese sample at the 1-year follow-up, and 0.093 (95% CI 0.061-0.125) for the British at the 2-year follow-up and 0.093 (95% CI 0.049-0.130) at the 4-year follow-up. This relationship disappeared in participants without baseline organic syndromes. In a multiple adjusted logistic regression analysis, an increased risk of organic syndromes seemed to be associated with baseline, mainly in the highest level of, depressive syndromes.

CONCLUSIONS

The relationship between syndromes of depression and dementia might be temporal. The lack of an obvious dose-response relationship between baseline depressive syndromes and follow-up dementia syndromes suggests that the causal relationship between depression and dementia needs further investigation.