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author:("Xu, xinghua")
1.  Use of Metformin Alone Is Not Associated with Survival Outcomes of Colorectal Cancer Cell but AMPK Activator AICAR Sensitizes Anticancer Effect of 5-Fluorouracil through AMPK Activation 
PLoS ONE  2014;9(5):e97781.
Colorectal cancer (CRC) is still the third most common cancer and the second most common causes of cancer-related death around the world. Metformin, a biguanide, which is widely used for treating diabetes mellitus, has recently been shown to have a suppressive effect on CRC risk and mortality, but not all laboratory studies suggest that metformin has antineoplastic activity. Here, we investigated the effect of metformin and AMPK activator AICAR on CRC cells proliferation. As a result, metformin did not inhibit cell proliferation or induce apoptosis for CRC cell lines in vitro and in vivo. Different from metformin, AICAR emerged antitumor activity and sensitized anticancer effect of 5-FU on CRC cells in vitro and in vivo. In further analysis, we show that AMPK activation may be a key molecular mechanism for the additive effect of AICAR. Taken together, our results suggest that metformin has not antineoplastic activity for CRC cells as a single agent but AMPK activator AICAR can induce apoptosis and enhance the cytotoxic effect of 5-FU through AMPK activation.
PMCID: PMC4029793  PMID: 24849329
2.  Global Population Structure and Evolution of Bordetella pertussis and Their Relationship with Vaccination 
mBio  2014;5(2):e01074-14.
Bordetella pertussis causes pertussis, a respiratory disease that is most severe for infants. Vaccination was introduced in the 1950s, and in recent years, a resurgence of disease was observed worldwide, with significant mortality in infants. Possible causes for this include the switch from whole-cell vaccines (WCVs) to less effective acellular vaccines (ACVs), waning immunity, and pathogen adaptation. Pathogen adaptation is suggested by antigenic divergence between vaccine strains and circulating strains and by the emergence of strains with increased pertussis toxin production. We applied comparative genomics to a worldwide collection of 343 B. pertussis strains isolated between 1920 and 2010. The global phylogeny showed two deep branches; the largest of these contained 98% of all strains, and its expansion correlated temporally with the first descriptions of pertussis outbreaks in Europe in the 16th century. We found little evidence of recent geographical clustering of the strains within this lineage, suggesting rapid strain flow between countries. We observed that changes in genes encoding proteins implicated in protective immunity that are included in ACVs occurred after the introduction of WCVs but before the switch to ACVs. Furthermore, our analyses consistently suggested that virulence-associated genes and genes coding for surface-exposed proteins were involved in adaptation. However, many of the putative adaptive loci identified have a physiological role, and further studies of these loci may reveal less obvious ways in which B. pertussis and the host interact. This work provides insight into ways in which pathogens may adapt to vaccination and suggests ways to improve pertussis vaccines.
Whooping cough is mainly caused by Bordetella pertussis, and current vaccines are targeted against this organism. Recently, there have been increasing outbreaks of whooping cough, even where vaccine coverage is high. Analysis of the genomes of 343 B. pertussis isolates from around the world over the last 100 years suggests that the organism has emerged within the last 500 years, consistent with historical records. We show that global transmission of new strains is very rapid and that the worldwide population of B. pertussis is evolving in response to vaccine introduction, potentially enabling vaccine escape.
PMCID: PMC3994516  PMID: 24757216
3.  JNK confers 5-fluorouracil resistance in p53-deficient and mutant p53-expressing colon cancer cells by inducing survival autophagy 
Scientific Reports  2014;4:4694.
Deficiency or mutation in the p53 tumor suppressor gene commonly occurs in human cancer and can contribute to disease progression and chemotherapy resistance. Currently, although the pro-survival or pro-death effect of autophagy remains a controversial issue, increasing data seem to support the idea that autophagy facilitates cancer cell resistance to chemotherapy treatment. Here we report that 5-FU treatment causes aberrant autophagosome accumulation in HCT116 p53−/− and HT-29 cancer cells. Specific inhibition of autophagy by 3-MA, CQ or small interfering RNA treatment targeting Atg5 or Beclin 1 can potentiate the re-sensitization of these resistant cancer cells to 5-FU. In further analysis, we show that JNK activation and phosphorylation of Bcl-2 are key determinants in 5-FU-induced autophagy. Inhibition of JNK by the compound SP600125 or JNK siRNA suppressed autophagy and phosphorylation of c-Jun and Bcl-2 but increased 5-FU-induced apoptosis in both HCT116 p53−/− and HT29 cells. Taken together, our results suggest that JNK activation confers 5-FU resistance in HCT116 p53−/− and HT29 cells by promoting autophagy as a pro-survival effect, likely via inducing Bcl-2 phosphorylation. These results provide a promising strategy to improve the efficacy of 5-FU-based chemotherapy for colorectal cancer patients harboring a p53 gene mutation.
PMCID: PMC3986705  PMID: 24733045
4.  Inhibition of the angiogenesis and growth of Aloin in human colorectal cancer in vitro and in vivo 
Angiogenesis has been an attractive target for drug therapy. Aloin (AL), an natural compound derived from Aloe barbadensis Miller leaves, has been shown to possess anti-cancer potential activities. However, its roles in tumor angiogenesis and the involved molecular mechanism are unknown.
To evaluate the antiangiogenic and anticancer activities of AL, endothelial cell scratch, modified Boyden chamber inserts and tube formation assays were done in HUVECs, and MTT and Live-Dead assays were used to determine the proliferation inhibition and apoptosis induction of colorectal cancer cells in vitro. The inhibition effects of AL were further confirmed by a mouse xenograft model in vivo. The expression levels of STAT3 signaling pathway and that mediated-target genes were measured in HUVECs and SW620 cells by Western blots.
Here, we demonstrated that AL significantly inhibited HUVECs proliferation, migration and tube formation in vitro. Western blotting showed that AL suppressed activation of VEGF receptor (VEGFR) 2 and STAT3 phosphorylation in endothelial cells. In addition, the constitutively activated STAT3 protein, and the expression of STAT3-regulated antiapoptotic (Bcl-xL), proliferative (c-Myc), and angiogenic (VEGF) proteins were also down-regulated in response to AL in human SW620 cancer cells. Consistent with the above findings, AL inhibited tumor cell viability and induced cell apoptosis in vitro, and substantially reduced tumor volumes and weight in vivo mouse xenografts, without obviously toxicity.
Our studies provided the first evidence that AL may inhibit tumor angiogenesis and growth via blocking STAT3 activation, with the potential of a drug candidate for cancer therapy.
PMCID: PMC3722112  PMID: 23848964
Aloin; Angiogenesis; Tumor growth; Colorectal cancer; STAT3
5.  Active autophagy in the tumor microenvironment: A novel mechanism for cancer metastasis 
Oncology Letters  2012;5(2):411-416.
Autophagy is a lysosomal degradation process which is key for the regulation of the turnover of long-lived or damaged proteins and organelles and which promotes cell survival during nutrient deprivation or other microenvironmental stresses. Current evidence supports the hypothesis that autophagy suppresses tumorigenesis, particularly during the early stages of tumor initiation. However, in established tumors, autophagy promotes survival under stressful conditions during cancer progression and in response to chemotherapy; however, the mechanism by which autophagy influences cancer metastasis remains unknown. In this review, we discuss the capacity of an abnormal tumor environment to induce autophagy and consider how this relates to tumor metastasis and the attractive prospect of manipulating autophagic signaling pathways as potential targets for the treatment of cancer metastasis.
PMCID: PMC3573143  PMID: 23420500
autophagy; microenvironment; metastasis; pathway; cancer
6.  Complete Genome Sequence of Bordetella pertussis CS, a Chinese Pertussis Vaccine Strain ▿  
Journal of Bacteriology  2011;193(15):4017-4018.
Bordetella pertussis is the causative agent of pertussis. Here, we report the genome sequence of Bordetella pertussis strain CS, isolated from an infant patient in Beijing and widely used as a vaccine strain for production of an acellular pertussis vaccine in China.
PMCID: PMC3147532  PMID: 21622744
7.  Effect of Vaccination on Bordetella pertussis Strains, China 
Emerging Infectious Diseases  2010;16(11):1695-1701.
Strains in China may differ from those in countries that have long histories of high vaccination coverage.
Whole-cell pertussis vaccine was introduced in China in the early 1960s. We used standard typing methods to compare 96 Bordetella pertussis isolates collected before and after introduction of vaccination, during 1953–2005. The following vaccine-type alleles of the pertussis toxin (ptx) gene were characteristic for all prevaccination strains: ptxA2, ptxA3, and ptxA4. The shift to ptxA1 occurred since 1963. All isolates collected since 1983 contained ptxA1. Pertactin (prn) allele 1, prn1, was predominant, although prn2 and prn3 have been detected since 2000. Serotypes fimbriae (Fim) 2 and Fim2,3 were found in all isolates collected before 1986. During 1997–2005, Fim3 became prevalent. Although changes in electrophoresis profiles over time were observed, the predominant profiles during 1997–2005 resembled those during the prevaccine era and those found in Europe before the 1990s. B. pertussis strains in China may differ from those in countries that have a long history of high vaccine coverage.
PMCID: PMC3294513  PMID: 21029526
China; Bordetella pertussis; whooping cough; pertussis; incidence; vaccination; genotyping; PFGE; bacteria; research
8.  Production and characterization of recombinant pertactin, fimbriae 2 and fimbriae 3 from Bordetella pertussis 
BMC Microbiology  2009;9:274.
Bordetella pertussis is a causative agent of pertussis or whooping cough in humans. Pertactin (Prn), fimbriae 2 (Fim2) and fimbriae 3 (Fim3) of B. pertussis are important virulence factors and immunogens which have been included in some acellular pertussis vaccines. In this present study, we cloned, expressed and purified Prn, Fim2 and Fim3, respectively. The immunogenicity and protective efficacy of the three recombinant proteins (rPrn, rFim2 and rFim3) were investigated in mouse model.
Three recombinant proteins with amount of 12 to 25 mg/L were produced. Compared to the control mice only immunized with adjuvant, serum IgG antibody responses were significantly induced in the mice immunized with rPrn, rFim2 or rFim3 (P < 0.001 for all three proteins). Furthermore, T cell responses characteristic of increased production of IL-2 and TNF-α (only for rPrn) were elicited in the mice immunized with the three proteins (P < 0.05 for all three proteins). Immunization with rPrn, but not with rFim2 or rFim3, significantly enhanced clearance of bacteria in the lungs of mice after intranasal challenge with B. pertussis (P < 0.05). When tested in a lethal intracerebral infection model, certain protection was observed in mice immunized with rPrn.
We have developed an efficient method to produce large amounts of rPrn, rFim2, and rFim3 from B. pertussis. The three recombinant proteins induced both humoral and cellular immune responses in mice. Immunization with rPrn also conferred protection against pertussis in mouse infection models. Our results indicated that the recombinant proteins still retain their immunological properties and highlighted the potential of the recombinant proteins for the future development of the B. pertussis vaccines.
PMCID: PMC2807877  PMID: 20040101
9.  The Basic Science of Tendinopathy 
Tendinopathy is a common clinical problem with athletes and in many occupational settings. Tendinopathy can occur in any tendon, often near its insertion or enthesis where there is an area of stress concentration, and is directly related to the volume of repetitive load to which the tendon is exposed. Recent studies indicate tendinopathy is more likely to occur in situations that increase the “dose” of load to the tendon enthesis – including increased activity, weight, advancing age, and genetic factors. The cells in tendinopathic tendon are rounder, more numerous, and show evidence of oxidative damage and more apoptosis. These cells also produce a matrix that is thicker and weaker with more water, more immature and cartilage-like matrix proteins, and less organization. There is now evidence of a population of regenerating stem cells within tendon. These studies suggest prevention of tendinopathy should be directed at reducing the volume of repetitive loads to below that which induces oxidative-induced apoptosis and cartilage-like genes. The management strategies might involve agents or cells that induce tendon stem cell proliferation, repair and restoration of matrix integrity.
PMCID: PMC2505234  PMID: 18478310

Results 1-9 (9)