Signal transducer and activator of transcription 3 (STAT3) regulates diverse cellular processes including cell growth, differentiation, and apoptosis, and is frequently activated during tumorigenesis. Recently, putative glioblastoma stem cells (GBM-SC) have been isolated and characterized. These cells can self-renew indefinitely in culture, are highly tumorigenic, and retain the ability to differentiate in culture. We have found that treatment of GBM-SC with two chemically distinct small molecule inhibitors of STAT3 DNA-binding inhibits cell proliferation and the formation of new neurospheres from single cells. Genetic knockdown of STAT3 using an shSTAT3-containing lentivirus also inhibits GBM-SC proliferation and neurosphere formation, confirming that these effects are specific to STAT3. While STAT3 inhibition can induce apoptosis in serum-derived GBM cell lines, this effect was not observed in GBM-SC grown in stem cell media. Markers of neural stem cell multipotency also decrease upon STAT3 inhibition, suggesting that STAT3 is required for maintenance of the stem-like characteristics of these cells. Strikingly, even a transient inhibition of STAT3 leads to irreversible growth arrest and inhibition of neurosphere formation. These data suggest that STAT3 regulates the growth and self-renewal of GBM-SC and is thus a potential target for cancer stem cell-directed therapy of glioblastoma multiforme.

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder in women. Gut microbiota has been implicated to play a critical role in metabolic diseases and may modulate the secretion of mediators of the brain–gut axis. Interaction between gut microbiota and the endocrine and biochemical disturbances in PCOS still remains elusive. Here, we showed an altered gut microbiota significantly correlated with PCOS phenotype. There were 33 patients with PCOS (non-obese PCOS individuals, PN, n = 12; obese PCOS individuals, PO, n = 21) as well as 15 control subjects (non-obese control individuals, CN, n = 9; obese control individuals, CO, n = 6) enrolled in our study. The plasma levels of serotonin, ghrelin, and peptide YY (PYY) were significantly decreased in patients with PCOS compared with controls, and have a significantly negative correlation with waist circumference and testosterone. Sequencing of the V3–V4 region of the 16S rRNA gene in fecal samples revealed the substantial differences of gut microbial species between the PCOS and non-obese controls. Bacterial species were clustered into 23 co-abundance groups (CAGs) based on the SparCC correlation coefficients of their relative abundance. The CAGs increased in PCOS, including the bacteria belonging to Bacteroides, Escherichia/Shigella and Streptococcus, were negatively correlated with ghrelin, and positively correlated with testosterone and BMI. Furthermore, the CAGs that were decreased in PCOS, including the bacteria from Akkermansia and Ruminococcaceae, showed opposite relationship with body-weight, sex-hormone, and brain–gut peptides. In conclusion, gut microbial dysbiosis in women with PCOS is associated with the disease phenotypes.

Results of earlier work had suggested that utilization of polysaccharides by Bacteroides spp. did not proceed via breakdown by extracellular polysaccharide-degrading enzymes. Rather, it appeared that the polysaccharide was first bound to a putative outer membrane receptor complex and then translocated into the periplasm, where the degradative enzymes were located. In a recent article, we reported the cloning and sequencing of susC, a gene from Bacteroides thetaiotaomicron that encoded a 115-kDa outer membrane protein. SusC protein proved to be essential for utilization not only of starch but also of intermediate-sized maltooligosaccharides (maltose to maltoheptaose). In this paper, we report the sequencing of a 7-kbp region of the B. thetaiotaomicron chromosome that lies immediately downstream of susC. We found four genes in this region (susD, susE, susF, and susG). Transcription of these genes was maltose inducible, and the genes appeared to be part of the same operon as susC. Western blot (immunoblot) analysis using antisera raised against proteins encoded by each of the four genes showed that all four were outer membrane proteins. Protein database searches revealed that SusE had limited similarity to a glucanohydrolase from Clostridium acetobutylicum and SusG had high similarity to amylases from a variety of sources. SusD and SusF had no significant similarity to any proteins in the databases. Results of 14 C-starch binding assays suggested that SusD makes a major contribution to binding. SusE and SusF also appear to contribute to binding but not to the same extent as SusD. SusG is essential for growth on starch but appears to contribute little to starch binding. Our results demonstrate that the binding of starch to the B. thetaiotaomicron surface involves at least four outer membrane proteins (SusC, SusD, SusE, and SusF), which may form a surface receptor complex. The role of SusG in binding is still unclear.Human colonic Bacteroides spp. can utilize a variety of polysaccharides as their sole source of carbon and energy. An unusual feature of Bacteroides polysaccharide utilization systems is that the degradative enzymes are cell associated rather than extracellular, and the binding of the polysaccharide to the cell surface appears to be an essential first step in the polysaccharide utilization process (2,3,28). We have used the starch utilization system of Bacteroides thetaiotaomicron as a model system for defining the various components involved in the polysaccharide utilization process, especially those that mediate early steps in starch uptake and digestion. B. thetaiotaomicron can utilize all forms of starch, including amylose, amylopectin, and pullulan, and their component maltooligosaccharides. Amylose consists of linear chains of ␣-1,4-linked glucose residues. Amylopectin consists of amylose chains linked to each other by ␣-1,6 branches. Pullulan is a linear chain of maltotriose residues connected by ␣-1,6 linkages.To date, we have characterized three structural genes that are involved in the breakdow...

Previous studies suggested that the first step in utilization of starch by Bacteroides thetaiotaomicron was binding of the polysaccharide to the cell surface, followed by translocation of the polysaccharide across the outer membrane into the periplasm. In this study, we report the molecular characterization of a gene that encodes an outer membrane protein that is essential for utilization of both maltooligosaccharides and starch. The gene, susC, encoded a protein of 115.3 kDa. Antibodies were raised against SusC, and the outer membrane location of SusC could be confirmed by Western blot (immunoblot) analysis. SusC had a possible signal sequence of between 20 and 39 amino acids, depending on which N-terminal methionine initiates the start of the protein. It also had some features typical of well-characterized outer membrane proteins from members of the family Enterobacteriaceae, such as a terminal phenylalanine residue and a region in the amino portion of the protein thought to be involved in stabilizing the protein in the outer membrane. The amino acid sequence, together with results of gene disruption experiments, suggested that SusC was not an amylolytic enzyme. Transcriptional fusion experiments, using beta-glucuronidase as a reporter group, showed that expression of susC was maltose regulated at the transcriptional level. This is the first molecular characterization of a B. thetaiotaomicron outer membrane protein involved in maltooligosaccharide and starch utilization.