Low expression of PDK1 inhibits renal cell carcinoma cell proliferation, migration, invasion and epithelial mesenchymal transition through inhibition of the PI3K-PDK1-Akt pathway

As the most commonly occurring form of primary renal tumor, renal cell carcinoma (RCC) is a malignancy accompanied by a high mortality rate. 3-phosphoinositide-dependent protein kinase 1 (PDK1) has been established as a protein target and generated considerable interest in both the pharmaceutical and academia industry. The aim of the current study was to investigate the effect of si-PDK1 on the RCC cell apoptosis, proliferation, migration, invasion and epithelial mesenchymal transition (EMT) in connection with the PI3K-PDK1-Akt pathway. Microarray analysis from the GEO database was adopted to identify differentially expressed genes (DEGs) related to RCC, after which the positive expression of the PDK1 protein in tissue was determined accordingly. The optimal silencing si-RNA was subsequently selected and RCC cell lines 786-O and A498 were selected and transfected with either a si-PDK1 or activator of the PI3K-PDK1-Akt pathway for grouping purposes. The mRNA and protein expressions of PDK1, the PI3K-PDK1-Akt pathway-, EMT- and apoptosis-related genes were then evaluated. The effect of si-PDK1 on cell proliferation, apoptosis, invasion and migration was then analyzed. Through microarray analysis of GSE6344, GSE53757, GSE14762 and GSE781, PDK1 was examined. PDK1 was determined to be highly expressed in RCC tissues. Si-PDK1 exhibited marked reductions in relation to the mRNA and protein expression of PDK1, PI3K, AKT as well as Vimentin while elevated mRNA and protein expressions of E-cadherin were detected, which ultimately suggested that cell migration, proliferation and invasion had been inhibited coupled with enhanced levels of cell apoptosis. While a notable observation was made highlighting that the PI3K-PDK1-Akt pathway antagonized the effect of PDK1 silencing. Taken together, the key observations of this study provide evidence suggesting that high expressions of PDK1 are found in RCC, while highlighting that silencing PDK1 could inhibit RCC cell proliferation, migration, invasion and EMT by repressing the PI3K-PDK1-Akt pathway.

IFN-gamma is associated with risk of Schistosoma japonicum infection in China

Before the start of the schistosomiasis transmission season, 129 villagers resident on a Schistosoma japonicum-endemic island in Poyang Lake, Jiangxi Province, 64 of whom were stool-positive for S. japonicum eggs by the Kato method and 65 negative, were treated with praziquantel. Forty-five days later the 93 subjects who presented for follow-up were all stool-negative. Blood samples were collected from all 93 individuals. S. japonicum soluble worm antigen (SWAP) and soluble egg antigen (SEA) stimulated IL-4, IL-5 and IFN-gamma production in whole-blood cultures were measured by ELISA. All the subjects were interviewed nine times during the subsequent transmission season to estimate the intensity of their contact with potentially infective snail habitats, and the subjects were all re-screened for S. japonicum by the Kato method at the end of the transmission season. Fourteen subjects were found to be infected at that time. There was some indication that the risk of infection might be associated with gender (with females being at higher risk) and with the intensity of water contact, and there was evidence that levels of SEA-induced IFN-gamma production were associated with reduced risk of infection.

[Clonning and identification of the gene encoding specific IgE antibody-related antigen of Schistosoma japonicum]

OBJECTIVE

To obtain the gene encoding specific IgE-related antigen of Schistosoma japonicum from the cDNA library of adult Schistosoma japonicum.

METHODS

The pooled sera from 15 individuals with high levels of specific IgE antibody against SWAP were absorbed with Protein-G and used for screening of IgE-related antigen from the adult worm cDNA library of Schistosoma japonicum. The inserted cDNA was amplified by PCR and sequenced. According to the first reading frame of the sequence, a pair of new probes, in which EcoR I and Not I sites were incorporated respectively, were designed and used to amplify the target gene. Then, the gene was cloned into vector pGEM-T and subcloned into expression vector pGEX-6p-1. The fusion protein was expressed, analysed by SDS-PAGE and identified by Western blotting with the specific IgE antibody, respectively.

RESULTS

The inserted cDNA fragment from the positive clone was about 1,200 bp, with the ORF of 507 bp which encoded 169 amino acids. The deduced molecular weight of the recombinant protein was 19.3 kDa. The homology between the target gene (Sj43B) and other known DNA sequences was less than 40%. The fusion protein expressed by the recombinant vector pGEX-6p-1/Sj43B could be recognized by schistosome specific IgE antibody.

CONCLUSION

Sj43B may encode the specific IgE-related antigen of Schistosoma japonicum. The successful construction of recombinant plasmid pGEX-6p-1/Sj43B lay the groundwork for further studies on immunological characteristics and protection immunity of the recombinant protein.

[Cloning and identification of deltamethrin-resistance or susceptibility associated genes of Culex pipiens pallens]

OBJECTIVE

To obtain deltamethrin-resistance or susceptibility associated genes of Culex pipiens pallens.

METHODS

The differentially expressed genes were obtained by suppression subtractive hybridization (SSH), and identified by cDNA microarray and reverse Northern blotting.

RESULTS

523 and 286 clones were selected respectively in the two directional SSH. 155 and 42 genes were respectively expressed 2-3 and > 3 times higher in the insecticide-resistant strain than in the susceptible strain; 15 and 9 genes were respectively expressed 2-3 and > 3 times higher in the susceptible strain than in the resistant strain. There were 2 genes only expressed in the insecticide-resistant strain. 51 three times differentially expressed clones and 2 specially expressed clones were sequenced. 44 sequences were obtained which belong to 13 new genes. There were 8 over-expressed genes in resistant strain, 7 of which were similar respectively to mitochondrion rRNA gene, 60S ribosomal protein gene, 40S ribosomal protein S4 gene, trypsin gene, chymotrypsin A gene, ospin gene, and 16S ribosomal RNA gene. There were 5 over-expressed genes in susceptible strain, 2 of them being similar with 40S ribosomal protein S29 gene and myosin regulatory light chain 2 gene. In addition, 2 genes specially expressed in resistant strain were similar respectively to glycogen branching enzyme gene and ribosomal protein 46 gene.

CONCLUSION

The differentially expressed genes may be associated with deltamethrin-resistance or susceptibility of Culex pipiens pallens.

[Analysis of the mitochondria-related protein of Schistosoma japonicum and its antigen epitopes]

OBJECTIVE

To sequence the cloned gene Sj338 and to identify the encoded protein and its antigen epitopes.

METHODS

The Sj338 gene fragment obtained from adult S. japonicum cDNA library amplified by PCR method was subcloned into pGEM-T vector for sequencing. The sequence of nucleotides and the characteristics of the encoded protein were analyzed by DNASIS Program and Goldkey DNA and Protein Analytical Program, and then the homology of the amino acid sequence was searched on the BLAST net.

RESULTS

The cloned rSj338 gene was demonstrated to be 487 bp containing one 459 bp ORF, encoding a protein consisted of 153 amino acids with a molecular weight of 17.6 kDa. The amino acid sequence of the recombinant protein rSj338 shared 46% identity with that of the corresponding part of human mitochondrial import receptor and 44% identity with that of the Rattus sp. mitochondrial precursor receptor. The possible antigen epitopes were predicted within the peptide fragments of 26-32 aa, 37-46 aa and 147-151 aa.

CONCLUSION

The protein encoded by rSj338 gene fragment might be the mitochondria-related protein of Schistosoma japonicum.

[Human parasite antigen-specific IFN-gamma response in schistosomitsis japonica endemic area]

OBJECTIVE

To explore the characteristics of human schistosome antigen-specific IFN-gamma response in a population in an area endemic for schistosomiasis japonica.

METHODS

Three neighboring villages were chosen on Nanshan Island of Poyang Lake. 65 egg-negative persons and 64 egg-positive ones were selected randomly from the residents aged 14-41 years according to the egg counts by Kato-Katz thick smear method. IFN-gamma was measured in the whole blood culture supernatant after stimulated by the schistosome soluble egg antigen (SEA) and soluble worm antigen preparations (SWAP). Serum isotype-restricted antibody was detected by ELISA.

RESULTS

IFN-gamma levels induced by both SEA and SWAP were increased significantly after praziquantel treatment. The SEA-specific IFN-gamma level of the uninfected group was much higher than that of the reinfected group. A negative correlation between IFN-gamma level and IgG4 production was found, reflecting that IFN-gamma might be associated with the resistance to schistosome reinfection.

CONCLUSION

The changes in IFN-gamma level might play an important role in association with the resistance to schistosome reinfection.

[Studies on human cytokine responses before and after praziquantel chemotherapy in an endemic area of schistosomiasis japonica]

OBJECTIVE

To observe the cellular immune responses in a population of an endemic area of schistosomiasis japonica and the influence of praziquantel treatment.

METHODS

Blood was taken from 129 residents (64 cases were egg-positive, 65 cases were egg-negitive) of an endemic area of Poyang Lake before and 45 days after praziquantel treatment. Cytokines induced by the schistosome soluble egg antigen (SEA) and soluble worm antigen preparations (SWAP) in the peripheral blood cells including IL-5, IL-10 and IFN-gamma were measured.

RESULTS

Among 129 cases, the cytokine levels were found much higher in egg negative individuals than in egg-positive individuals. The cytokine levels induced by both antigens were increased significantly after praziqantel treatment especially IL-5 and IFN-gamma.

CONCLUSION

The cellular immune responses in the population in schistosomiasis japonica endemic area exhibited a general trend of down-regulation and were elevated significantly after praziquantel treatment.

[Gene cloning and characterization of mitochondria-related protein of Schistosoma japonicum]

OBJECTIVE

To subclone and characterize a cDNA clone coding for Schistosoma japonicum (S.j.) mitochondria-related protein.

METHODS

The open reading frame of the fragment(Sj338/24) obtained from an adult worm cDNA library of S.j. was analysed, at the upstream and downstream of the open reading frame(ORF) the primers A and B were designed, respectively, and the cDNA fragment was used as PCR template. The Sj338 gene fragment obtained was amplified by PCR method and then subcloned into pGEM-T vector for sequencing. The gene sequence was analyzed and the target fragment was restrictedly digested and subcloned into expression vector pGEX-6P-1. The expressed recombinant protein was purified and characterized.

RESULTS

The cloned Sj338 gene was demonstrated to be 487 bp long containing one 459 bp ORF, encoding a protein with a molecular weight of 17 kDa. The nucleotide sequence of the cloned gene Sj338 had higher homology with those genes coding for mitochondrial outer membrane protein of Homo sapiens and Rattus norvegicus. The recombinant construct of pGEX-6P-1/Sj338 could be expressed efficiently and the antigenicity of its product rSj338 has been demonstrated by Western blotting.

CONCLUSION

Sj338 may be the gene coding for S.j. mitochondria-related protein and the recombinant protein may be used as a new vaccine candidate.

[Cloning and identification of cytochrome P450 resistance related genes in the mosquito, Culex pipiens pallens]

OBJECTIVE

To inquire into the relationship between cytochrome P450 and deltamethrin resistance.

METHODS

24 new cDNA sequences encoding cytochrome P450 were amplified respectively from deltamethrin-susceptible and -resistant strains of Culex pipiens pallens with a pair of degenerate primers according to the conservative amino acid sequences of CYP4 in insects by RT-PCR and the Direct Cloning Method, and then were identified by cDNA chip and reverse Northern.

RESULTS

112 positive clones were obtained, of which 24 were shown to be new sequences encoded for cytochrome P450. They have been lodged in GenBank and were appraised by the Nomenclature Committee of Cytochrome P450, belonging to the subfamily CYP4C, CYP4D, CYP4H and CYP4J in CYP4 family. The hybrid signal values of 6 P450 sequences (NYDS3, NYDS5, NYDR6, NYDR9, NYDR15 and NYDR17) were 3.1-9.7 times higher in the resistance probe than in the susceptible probe, and NYDR17 only reacted with the resistance probe. The result of reverse Northern in NYDR15 was similar to that of cDNA chip.

CONCLUSION

CYP4 is related to deltamethrin resistance and the specific expression caused by point mutation of cytochrome P450 gene may exist in deltamethrin-resistant Cx. pipiens pallens.

Down-regulation of specific antigen-driven cytokine production in a population with endemic Schistosoma japonicum infection

Schistosome antigen-driven cytokine responses and antischistosome antibody levels of residents of a Schistosoma japonicum endemic island in Poyang Lake, Jiangxi Province were studied before and 45 days after treatment with praziquantel. IL-4, IL-5, IL-10 and INF-gamma were all detected in the supernatants of whole-blood cultures after stimulation with schistosome soluble egg antigen (SEA) and soluble worm antigen preparation (SWAP). The percentages of subjects producing detectable amounts of each cytokine assayed were higher in the group who were negative by stool examination at the start of the study than in those who were initially stool positive. After praziquantel treatment the percentages of subjects producing both type I and type II cytokines increased. This suggests that the production of both types of cytokine was down-regulated in the presence of live, egg-laying S. japonicum adult worms but that this was reversible by treatment. In contrast, the antibody studies showed higher levels of SWAP and SEA-specific antibodies (IgE, total IgG, IgG4, IgM) in subjects who were originally stool-positive than in those who were stool-negative. After treatment specific IgE responses were elevated, but total IgG and IgG4 anti-SEA and IgM anti-SWAP antibody levels all fell significantly.

[Studies of the genetic polymorphism of Schistosoma japonicum (Chinese mainland strains)]

In order to analyze the interspecies diversity and the extent of diversity among Schistosoma japonicum Chinese mainland strains, the genetic variation on gene level among 6 isolates collected from Jiangxi, Hunan, Hubei, Anhui, Sichuan, Yunnan and a cultured isolate from a laboratory were studied using molecular biological technique. There were only two different bases at position 112 and 143 in 536 bp sequence of 28S rDNA-D2 domain between Anhui and Yunnan isolates, the homology was 99.6%. The result could be explained the reason of why the migration rates of single chain 28S rDNA-D2 domain among the above 7 isolates were the same completely in PCR-SSCP. However, comparing with the sequences of the Philippine isolate of S. japonicum, S. mansoni and S. aematobium, there were 6, 94 and 93 different bases and the homologies were 98.9, 82.5 and 82.7 per cent separately. With 8 restriction endonucleases to analyze the ITS of rDNA obtained by PCR from the 7 isolates, the results showed that only 3 minor bands were different, e.g. 5.3% of total 58 fragments. It was suggested that the ITS of rDNA among 7 isolates were highly conserved. Using randomly amplified polymorphic DNA (RAPD) to analyze the genetic diversity of the genomes of the 7 isolates, the average genetic distance (D) calculated from total 284 amplified fragments was 0.22. The maximum D was 0.30 and existed between Anhui and Yunnan isolates. The minimum D was 0.13 and existed between Sichuan and Yunnan isolates. The clustering analysis of genetic distances showed that the 7 isolates could be gathered in one group. From above three results, it could be considered that the genetic diversity on gene level among S. japonicum Chinese mainland strains was very low.

[A case-control study on risk factors for definite and borderline hypertension]

To study the risk factors for definite and borderline hypertension (HBP), a pair-matched case-control study was conducted with data from the outpatient service of department of internal medicine in Tianjin Binjiang Hospital in 1991-1992. The cases were selected from 312 patients with definite and borderline HBP diagnosed during period 1990-1992 and those newly identified during the survey. The controls were selected from other subjects with no histories of cardiovascular disease and matched by age and sex. The conditional logistic regression model was used by definition of definite and borderline HBP for analysis. The results showed that the risk factors for developing definite or borderline HBP were: family history of HBP, lower level of education, higher weight or body mass index (kg/m2). The association of all these variables with definite HBP were more significant than that with borderline HBP.

[Video-assisted thoracoscopic surgery for chest disease]

Video-assisted thoracoscopic surgery was applied in a total of 20 patients, since Dec. 1992. There were 16 man and 4 woman whose ages ranged from 20 to 65 years. Three patient had a wedge resection for lung tumors, one a lobectomy for tracheaectasy, eleven with recurrent spontaneous pneumothorax were successfully treated, Pleural tumors (n = 1), pulmonary cyst (n = 1), Three biopsy of lung. The advantages of this for patients include cosmetic considerations, a shorter operation period, low pain, earlier postoperation mobilization.

The association between breast cancer and diet and other factors

To explore the effects of diet and other factors on breast cancer development, a case-control study was conducted in Tianjin between 1986-87. After adjusting for confounding factors, it was found that factors associated with increased risk of breast cancer included --early age at menarche; late age at menopause; late age at first birth; high Qutelet's index; histories of breast wound, disease and benign tumor; and a family history of malignant tumor, high fat, high calorie, low vegetable intake; elevated serum cholesterol and LDL-cholesterol; and lower levels of serum HDL-cholesterol and whole blood selenium.

Gas-filled liposomes as echocardiographic contrast agents in rabbits with myocardial infarcts

RATIONALE AND OBJECTIVES

The authors evaluated gas-filled liposomes as echocardiographic contrast agents in rabbits with myocardial infarcts.

METHODS

Ten rabbits underwent ligation of the left anterior descending coronary artery. Five animals underwent echocardiography before and after production of myocardial infarct (MI) and four animals had post-MI imaging only. In either case, images were obtained before and after injection of a single dose of 1 mL of gas-filed liposomes. Three radiologists blinded to clinical information reviewed the pre- and postcontrast images and assessed endomyocardial border definition, wall motion, confidence levels for normal versus abnormal wall motion and visualization of papillary muscle and mitral valve.

RESULTS

Postcontrast scans showed significant improvement (P < .05) in endomyocardial border definition, visualization of wall motion, papillary muscle and mitral valve as well as increased reader confidence level.

CONCLUSIONS

These results are encouraging and suggest that gas-filled liposomes may be a useful contrast agent for echocardiography.

Immunodiagnosis of Schistosoma japonicum infection in China

Diagnosis is an essential prerequisite for the control programs of schistosomiasis. Chinese scientists have been making efforts for decades towards the development of immunological approach in an attempt to offer alternatives of or supplements to parasitological diagnosis. The authors outline briefly the main advances in the research of immunodiagnosis for schistosomiasis japonica in China in two catalogues: antibody detection and antigen detection. A number of immunodiagnostic assays based on antibody detection, which have been used widely in the control programs in China, are appraised in terms of sensitivity and specificity, and the achievements in the development of immunodiagnostic assays based on antigen detection are introduced. Readers will find some information concerning the efforts so far made by Chinese scientists in the improvement of immunodiagnosis by use of molecular approach, including search for biochemically and/or immunochemically isolated and/or purified antigens, recombinant antigens and anti-idiotypic reagents of diagnostic interest to construct defined antigen-antibody systems for diagnosis, and development of monoclonal antibody-based assays for antibody or antigen detections.

Liposomes as MR contrast agents: pros and cons

Liposomes are generally thought of as being useful for entrapping drugs within their internal aqueous space. When used with MR contrast agents, this has the drawback that water flux across the membrane bilayer is limiting to contrast enhancement. This can be partially overcome by making the liposomes very small, such that surface area is relatively great compared to internal volume, thereby facilitating water exchange. Alternatively the membranes can be designed to be permeable to water but this may render the vesicles unstable in serum. Another approach is to incorporate the contrast agents into the lipid bilayer. By designing novel complexes of manganese with the ligands incorporated onto dual acyl chains, we have achieved R1 and R2 values of over 20/mmol sec-1 or more than five times higher than Gd-DTPA. Hepatic metastasis detection is significantly improved in rats at doses of only 10 mumol/kg manganese. Membrane-bound manganese complexes function as highly effective liver imaging agents and merit further study for development as agents to undergo human clinical trials.

[1:R matched case-control studies with fixed and varying numbers of controls]

This paper introduces the use of the Mantel-Haenszel estimator in 1:R matched case-control studies with fixed and varying numbers of controls matched to each case. The new methods of variance estimator of the Mantel-Haenszel estimator of a common odds ratio were provided. These methods were also summarized into the method of calculating table in order to present a simple, convenient and easily understanding method for the readers.

[Studies on DNA methylation in transformed mouse liver cells]

Activity of DNA methylase and DNA methylation level were measured from normal mouse liver, mouse liver charged with H22a ascitic hepatoma and H22a ascitic hepatoma cell by measuring incorporation of H3-methyl. S-Adenosyl-3H-methyl-methionine (3H-SAM) was used as methyl donor. DNA methylation level of different cells were measured by HP-LC. DNA methylase activity and DNA methylation level of H22a ascitic hepatoma, mouse liver charged with H22a ascitic hepatoma are lower than normal mouse liver. Treatments of antitumor drugs lead to a rising of DNA methylase activity of tumor cell, however, the DNA methylation level of tumor cell has not rised after such treatments.