Relationships between MGMT promoter methylation and gastric cancer: a meta-analysis.

A DNA repair enzyme, O6-methylguanine-DNA methyltransferase (MGMT), plays an important role in the development of gastric cancers. However, the role of MGMT promoter methylation in the occurrence of gastric cancer and its relationships with clinicopathologic characteristics has not been fully clarified. Thus, we performed a meta-analysis to evaluate the associations between MGMT promoter methylation and gastric cancer. Electronic databases, including PubMed and Web of Science, were used to systematically search related clinical studies published in English until April 1, 2016. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to evaluate the associations between MGMT promoter methylation and gastric cancer risk or clinicopathologic characteristics. A total of 16 studies including 1,935 patients and 1,948 control persons were included in the analysis. Our study suggested that MGMT promoter methylation frequency was associated with gastric cancer (OR=3.46, 95% CI: 2.13-5.61, P<0.001). Moreover, the frequency of MGMT promoter methylation in the no lymph node metastasis group was lower than that in lymph node metastasis group, with marginal significance (OR=0.65, 95% CI: 0.42-1.01, P=0.05). Additionally, the methylation rate of the MGMT promoter was much lower in patients without distant metastases than in those with metastases (OR=0.27, 95% CI: 0.18-0.40, P<0.001). No significant association of MGMT promoter methylation with Lauren classification, tumor location, tumor invasion, or Helicobacter pylori infection was found. In conclusion, the methylation status of the MGMT promoter was related to gastric cancer risk, distant metastasis, and lymph node metastasis, which indicates that MGMT promoter methylation may play an important role in gastric cancer development.

Ability of TEP1 in intestinal flora to modulate natural resistance of Anopheles dirus.

Blocking transmission of malaria is a reliable way to control and eliminate infection. However, in-depth knowledge of the interaction between Plasmodium and mosquito is needed. Studies suggest that innate immunity is the main mechanism inhibiting development of malaria parasites in the mosquito. Recent studies have found that use of antibiotics that inhibit the mosquito gut flora can reduce the immune response of Anopheles gambiae, thereby contributing to the development of malaria parasites. In our study, we used the non susceptible model of Anopheles dirus-Plasmodium yoelii to explore the effect of Anopheles intestinal flora on the natural resistance of A. dirus to P. yoelii. We found that in mosquitoes infected with Plasmodium, the intestinal flora can regulate expression of thioester-containing protein (TEP1) via an RNAi gene-silencing approach. Our results suggest that in the absence of TEP1, the natural microbiota cannot suppress the development of P. yoelii in A. dirus. This suggests that AdTEP1 plays an important role in the resistance of A. dirus to P. yoelii. The intestinal flora may modulate the development of P. yoelii in A. dirus by regulating TEP1 expression.

[Function of TEP1 gene during Plasmodium yoelii infection in Anopheles dirus].

OBJECTIVE: To study the role of TEP1 gene from Anopheles dirns during Plasmodium yoelii infection by RNA interference. METHODS: TEP1 primers with T7 promoter were designed based on the sequence of An. dirus TEP1 gene from GenBank database. PCR amplification of TEP1 gene was completed with An. dirus cDNA as template. The AdTEP1 double-stranded RNA was synthesized by using in vitro transcription kit with purified PCR products. Female An. dirus emerged for 1-2 days were divided into three groups each with 200 mosquitoes: TEP1 interference group, EGFP interference group and control. Mosquitoes in TEP1 and EGFP interference groups were microinjected in chest with 147 ng of AdTEP1 and EGFP double-stranded RNA, respectively, while those of control group were untreated. Effect of TEP1 interference on P. yoelii in An. dirus was estimated through semi-quantitative PCR with internal reference AdS7 at 3 d after injection. On 4 d after injection, mosquitoes were infected by EGFP-expressing P. yoelii BY265. The infection rate and infectivity of mosquitoes were observed through anastomosing 25 midguts from each group at 9 d post-infection. RESULTS: The AdTEP1 double-stranded RNA did well in the interference of TEP1 expression in An. dirus. The infection rate in the groups of control, EGFP and TEP1 interference was (24 +/- 2.83)%, (24 +/- 0.71)%, and (80 +/- 3.54)%, respectively; and the infectivity of the three groups was 0.32 +/- 0.7, 0.44 +/- 0.85, and 5.52 +/- 4.84, respectively. CONCLUSION: AdTEP1 interference increases the infection rate and infectivity of An. dirus by P. yoelii, and raises the susceptibility of An. dirus to P. yoelii significantly. TEP1 plays a critical role in the process of P. yoelii infection.

Differential proteins of the optic ganglion in octopus vulgaris under methanol stress revealed using proteomics.

An analytical approach using the two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) technique separated the proteome from the optic ganglia of Octopus vulgaris (OVOG). Approximately 600 protein spots were detected from the extraction when applying 150 µg protein to a 2D-PAGE gel in the pH range 5.0-8.0. Compared to the control, significant changes of 18 protein spots were observed in OVOG under the stress of native seawater containing 2% methanol for 72 h. Among these spots, we found that eight were down-regulated and ten were up-regulated in the gels, which were further identified using both peptide mass fingerprinting and database searches. Significant proteins such as glyceraldehyde-3-phosphate dehydrogenase, alpha subunit of succinyl-CoA synthetase, alcohol dehydrogenase, and long-chain specific acyl-CoA dehydrogenase were up-regulated proteins, whereas putative ABC transporter was a down -regulated protein. These differential proteins at the level of subcellular localization were further classified using LOCtree software with a hierarchical system of support vector machines. We found that most of the differential proteins in the gel could be identified as mitochondrial proteins, suggesting that these protective or marker proteins might help to prevent methanol poisoning via the mitochondria in the optical ganglia. The results indicated that both beta-tubulin and beta-actin were potential biomarkers as up-regulated proteins for monitoring methanol toxicosis associated with fish foods such as octopus and shark.

Plasmodium yoelii: correlation of TEP1 with mosquito melanization induced by nitroquine.

The antimalarial drug nitroquine is not only an effective antimalarial drug, it is also able to induce the melanization of Plasmodium species. However, the molecular mechanisms of the recognition reaction induced by this drug remain unclear. Silencing of thioester-containing protein-1 (TEP1) significantly compromised the ability of Anopheles gambiae to melanize the Plasmodium, leading to investigation of the involvement of A. stephensi TEP1 in melanization induced by nitroquine. This study shows that (1) binding of AsTEP1 to oocysts, especially melanized oocysts, (2) after ingestion of anti-AsTEP1 antibody, the melanization rate in antibody-treated mosquitoes are significantly lower than in control mosquito (p<0.05). The results suggest that nitroquine is able to induce Plasmodium recognition by TEP1, possibly triggering the resulting melanotic encapsulation. Further elucidation of the molecular mechanisms of mosquito immunity induced by antimalarial drugs will provide theoretical evidence for the use of antimalarial drugs, and a meaningful pathway for the design of novel antimalarial drugs.

Involvement of prophenoloxidases in the suppression of Plasmodium yoelii development by Anopheles dirus.

Anopheles dirus is refractory to a rodent malaria parasite, Plasmodium yoelii, and melanized oocysts are manifested in infected mosquitoes. Prophenoloxidase (PPO) is a zymogen whose active form mediates melanotic encapsulation of invading pathogens in mosquitoes. In this study, we cloned cDNA fragments of four An. dirus PPOs, that are orthologs of Anopheles gambiae PPO2, PPO4, PPO5 and PPO6. AdPPO4 expression in hemocytes was induced in response to P. yoelii infection. RNA interference using double stranded RNA of AdPPO4 led to depletion of its mRNA and other PPO transcripts. This depletion increased P. yoelii infection prevalence and oocyst intensity, and abolished the melanization of oocysts as well. Therefore, An. dirus PPOs may play a role in the refractoriness to P. yoelii.

[Inhibition of CpG oligodeoxynucleotide on the development of pre-erythrocytic stage of Plasmodium].

OBJECTIVE: To study the role of cytidine-phosphate-guanosine oligodeoxynucleotide (CpG ODN) on the development of Plasmodium liver stage. METHODS: Plasmodium yoelii BY265 18S rRNA was cloned, and the TaqMan real-time PCR was established on P. yoelii BY265 18S rRNA and mouse GAPDH as quantitative analysis model. The model was tested by the level of liver Plasmodium load with the liver cDNA in BALB/c mice infected by salivary gland sporozoites for 42 hours. Twelve BALB/c mice were randomly divided into CpG group, CpG control group and PBS control group which were injected respectively by ODN1826 30 microg, ODN1826 control 30 microg and 0.01 mol/L PBS 200 microl via vena caudalis. Twenty-four hours later, each mouse was inoculated with 100 sporozoites. Mice were sacrificed in 42 hours after infection, and the liver load of Plasmodium was analyzed by TaqMan real-time PCR. RESULTS: The cloned Py BY265 18S rRNA gene showed 98% similarity to Py 17XNL. The quantitative analysis model consisted by 18S rRNA and GAPDH showed positive correlation between the level of liver Plasmodium load and the sporozoite inoculation dose to mice. The Plasmodium load in CpG ODN pre-treated mice was reduced to one fifth of the control group (0.28/1.33) (P<0.05). CONCLUSION: The quantitative analysis model of TaqMan RT-PCR can detect the liver load of Plasmodium parasites, and CpG ODN can inhibit the development of its pre-erythrocytic stage.

[Correlation of Anopheles TEP1 gene with melanization induced by nitroquine].

OBJECTIVE: To analyze the relationship between the TEP1 gene of Anopheles stephensi and melanotic encapsulation of Plasmodium yoelii induced by anti-malaria drug nitroquine. METHODS: Haemolymph samples from three groups of An. stephensi fed with sucrose solution, Plasmodium-infected blood and nitroquine, respectively, were collected at the 1st, 2nd, 3rd and 4th day after drug administration. Degenerate primers were designed according to the conserved amino acid sequence within TEPs of the mosquitoes. Fluorescent quantitation PCR was used to detect the variation of TEP1 gene transcript induced by nitroquine. The melanization of oocysts was observed by light microscopy. RESULTS: TEP1 gene was cloned, the predicted amino acid residues harbored a highly conserved canonical thioester motif GCGEQ. The fluorescent quantitation PCR revealed that nitroquine induced an up-regulation of TEP1 activity. The transcription of TEP1 gene in nitroquine treated group (2.423) was significantly higher than that of the infected blood-fed group(1.036) at the 3rd day after nitroquine treatment (P<0.05). At the same time, most oocysts were found to be encapsulated in nitroquine treated group, while no melanized parasites were observed in the infected blood-fed group. CONCLUSION: Transcriptional variation of TEP1 gene may be related to the melanization induced by nitroquine.

Plasmodium yoelii: correlation of up-regulated prophenoloxidase and phenoloxidases with melanization induced by the antimalarial, nitroquine.

Although knowledge of the mosquito immune response has recently improved, less is known about the impact of antimalarial drugs on mosquito immunity. In the present study, we found that nitroquine, an effective antimalaria drug, could also induce melanotic encapsulation of Plasmodium by Anopheles stephensi. The melanization rate of the nitroquine treated group was 60.8%. To explore the effect of nitroquine on mosquito immunity, we determined the increase in activity of phenoloxidases (PO) enzyme, the main component of melanotic encapsulation, with nitroquine treatment. Moreover, we cloned prophenoloxidase (PPO) gene, which is accepted as the inactive phenoloxidase form and observed inducible expression of this gene with nitroquine treatment by real-time PCR. Our data implied that up-regulation of PPO gene and PO activity might be correlated with nitroquine. Nevertheless, nitroquine had no effect on the transcription of PPO gene or the activity of PO enzyme in the mosquito fed on a normal blood meal. In our study, we also observed the degenerative effect of 0.1% nitroquine on Plasmodium in the mosquito. This suggests that the degeneration of Plasmodium induced by nitroquine might result in the exposure of pattern-recognition ligands which can active the immune reaction, up-regulate PPO gene expression and PO activity, and induce the melanization.

Two serine proteases from Anopheles dirus haemocytes exhibit changes in transcript abundance after infection of an incompatible rodent malaria parasite, Plasmodium yoelii.

Serine proteases are involved in regulation of innate immune responses, such as haemolymph coagulation, melanization reaction and antimicrobial peptide synthesis. Although several serine proteases have been characterized in Anopheles gambiae (A. gambiae), few were cloned from other malaria vectors. In this study, we identified three cDNA fragments of serine proteases (AdSp1, AdSp2 and AdSp3) from haemocytes of an oriental malaria vector, Anopheles dirus (A. dirus), by cloning of fragments amplified with degenerate primers into the T-vector. RT-PCR analysis demonstrated that both AdSp1 and AdSp3 genes were also expressed in salivary gland. Basic local alignment search tool (BLAST) search found that both AdSp1 and AdSp3 were highly similar in sequence to A. gambiae Sp14A and Sp14D2, insects prophenoloxidase activating enzyme (PPAE) and Drosophila protease easter. Semi-quantitative RT-PCR indicated the transcription level of both AdSp1 and AdSp3 in haemocytes of A. dirus infected with Plasmodium yoelii (P. yoelii) was significant higher than that fed on 5% glucose or normal mouse blood at 7 days after the infectious meal (p<0.05), when P. yoelii oocysts began to be melanized by A. dirus. Our results indicated that both AdSp1 and AdSp3 might play an important role during melanotic encapsulation of P. yoelii by A. dirus.

[A family history of congenital fibrosis of the extraocular muscle with autosomal dominant inheritance].

To discover novel disease genes, a family with congenital fibrosis of the extraocular muscle was studied by a follow-up investigation, eye examinations and histo-pathological examination. There were fifteen cases suffering from congenital general fibrosis syndrome in four generations. They have congenital blepharoptosis, head tilt, chin lift, primary gaze fixed in a hypo- and exotropic position. The diagnosis is confirmed with positive forced duction testing in the affected eye. Furthermore, fibrosis of the extraocular muscles and hyaline degeneration was confirmed by histo-pathological examination. Except for different levels of restriction of the eyeball movements, other eye symptoms in positive patients are substantially identical. The genetic analysis showed that this disease was caused by autosomal dominant inheritance. The pedigree may be precious resource candidate for discovering disease gene related with congenital fibrosis of the extraocular muscle.

[Cloning, location and differential analysis of transcription factor Relish gene from Anopheles stephensi under different feeding conditions].

OBJECTIVE: To clone, locate and differentially analyze the transcription factor Relish gene from Anopheles stephensi, and to examine its signals-modulating action on prophenoloxidase cascade and melanization of Plasmodium yoelii oocysts. METHODS: Relish cDNA of total mosquitoes was amplified by RT-PCR with degenerated primers. Target PCR product was purified, cloned, sequenced and identified. Special Relish gene was amplified with specific primers from hemocytes or midgut, respectively. Semi-quantitative analysis was made under different feeding conditions. Relish message ribonucleic acid was identified with hybridization in situ. RESULTS: One cDNA segment of Relish similar to An. gambiae was acquired from An. stephensi. The same Relish gene was also manifested in the hemocytes and midgut. Marked up-regulation expression of Relish was observed at 6, 12, 24 or 48 h of Plasmodium yoelii infection and at 12 and 24 h after sucking nitroquine-acetate sucrose solution, that was before inducible oocyst melanization. Relish was also expressed in the hemocytes and midguts by ISH. CONCLUSION: Transcription factor Relish of An. stephensi might play a role in signal modulation of Plasmodium yoelii infection and oocyst melanization.

[cDNA cloning and location of Pagumogonimus skrj abini cysteine protease].

OBJECTIVE: To clone the cysteine protease cDNA fragment from Pagumogonimus skrjabini adults and locate the tissue of the adult worm where cysteine protease is expressed. METHODS: The cysteine protease cDNA fragment was amplified by reverse transcription-polymerase chain reaction (RT-PCR) with degenerated primers. The production was TA-cloned into the pUCm-T vector and sequenced. DNASIS program was used to analyse the nucleotide sequence and deduce the amino acid sequence, which was aligned with the correlated parasite cysteine protease afterwards. The digoxin labeled cRNA probe was synthesised by in vitro transcription with the cloned cDNA as template. The frozen sections of the adult worms were analysed by hybridization in situ to locate the gene expression. RESULTS: A 495 bp cDNA fragment was amplified by RT-PCR and sequenced. An amino acid sequence was deduced by DNASIS. Sequence analysis and alignment showed significant homologies with the correlated parasite cysteine proteinases and conservation of Cys, His and Asn residues that from a catalytic triad. In the hybridization in situ analysis, intestinal epithelium was stained positively on transverse section of adult worms. CONCLUSION: The cysteine proteinase cDNA fragment from Pagumogonimus skrjabini adults was cloned. There are some key sites which are correlated to the function of cysteine protease in the cDNA fragment. Cysteine protease is mainly expressed in intestinal epithelium of P. skrjabini.

[The internal control role of ribosomal protein S7 in the defense of Anopheles dirus against Plasmodium infection].

OBJECTIVE: To investigate the role of ribosomal protein S7 (rpS7) in the defense of Anopheles dirus against infection. METHODS: rpS7 was amplified from Anopheles dirus hemocytes with degenerated primers designed according to the conservative region of S7, rpS7 was then cloned using T/A cloning kit and the inserted fragment was sequenced. The difference of the transcript abundance of rpS7 from Anopheles dirus hemocyte among non-blood-fed (N), normal-blood-fed (B) and Plasmodium yoelii infected groups (I) was also analyzed by RT-PCR and gel scanning system at d1, d2, d3, d4, d7 and d11 after blood feeding. RESULTS: There is no significant difference of rpS7 signal between the three groups. CONCLUSION: Anopheles dirus S7 can be used as an internal control to study the role of Anopheles dirus related immune factors in Plasmodium infection.

[Assay of haemolymph protein concentration in Anopheles stephensi].

OBJECTIVE: To ascertain the changes of haemolymph protein concentration in adult Anopheles stephensi mosquitoes under different feeding conditions. METHODS: Haemolymph samples from four groups of adult An. stephensi, fed with sucrose solution, normal blood, plasmodium-infected blood and nitroquine, respectively, were collected by expulsion method. The concentration of haemolymph protein was examined by Bradford method. The results were analyzed automatically by Excel program. RESULTS: The level of protein concentration in the infected blood-fed group was higher than the sucrose solution group and normal blood group at day 8 after Plasmodium yoelii infection, the average concentration was 4.436, 3.080 and 3.092 micrograms/microliter, respectively. The haemolymph protein concentration (2.264 micrograms/microliter) in the nitroquine-administered mosquitoes was lower than the infected blood-fed mosquitoes. CONCLUSION: The haemolymph protein concentration of the adult An. stephensi decreases after the nitroquine administration, indicating that the haemolymph proteins may be involved in the melantotic encapsulation reaction of plasmodial oocysts.