Primary high-grade serous ovarian cancer cells are sensitive to senescence induced by carboplatin and paclitaxel in vitro.

BACKGROUND: Various types of normal and cancer cells undergo senescence in response to carboplatin and paclitaxel, which are considered the gold standard treatments in ovarian cancer management. Surprisingly, the effect of these drugs on ovarian cancer cell senescence remained unknown. METHODS: The experiments were conducted on primary high-grade serous ovarian cancer cells. Molecular markers of senescence were evaluated using cytochemistry and immunofluorescence. Cell cycle distribution was analyzed using flow cytometry. Expression of cyclins and signaling pathways was tested using western blot. Telomere length and telomerase activity were measured using qPCR, and the colocalization of telomeres with DNA damage foci using immuno-FISH. Oxidative stress-related parameters were quantified using appropriate fluorescence probes. Production of cancerogenic agents was analyzed using qPCR and ELISA. RESULTS: Carboplatin applied with paclitaxel induces senescence of ovarian cancer cells in vitro. This activity was reflected by permanent G2/M growth arrest, a high fraction of cells expressing senescence biomarkers (SA-ß-Gal and γ-H2A.X), upregulated expression of p16, p21, and p53 cell cycle inhibitors, and decreased expression of cyclin B1. Neither telomere length nor telomerase activity changed in the senescent cells, and the majority of DNA damage was localized outside telomeres. Moreover, drug-treated cancer cells exhibited increased production of STAT3 protein, overproduced superoxide and peroxides, and increased mitochondrial mass. They were also characterized by upregulated ANG1, CCL11, IL-6, PDGF-D, TIMP-3, TSP-1, and TGF-ß1 at the mRNA and/or protein level. CONCLUSIONS: Our findings imply that conventional chemotherapy may elicit senescence in ovarian cancer cells, which may translate to the development of a cancer-promoting phenotype, despite the inability of these cells to divide.

Exopolysaccharides Produced by Lactobacillus rhamnosus KL 53A and Lactobacillus casei Fyos Affect Their Adhesion to Enterocytes.

Probiotics promote and help to maintain beneficial microbiota composition of the gastrointestinal tract ecosystem and have a positive impact on the host's health. Production of exopolysaccharides is an important feature of probiotic lactobacilli. It increases the chance of their survival in the gastrointestinal tract and promotes adhesion to the epithelium; therefore, exopolysaccharides are important for the process of colonization. Two lactic acid bacteria strains were used in this study: Lactobacillus rhamnosus KL 53A and Lactobacillus casei Fyos. Exopolysaccharides were isolated from bacterial cells and their monosaccharide composition was examined using liquid chromatography. The influence of exopolysaccharides on lactobacilli adhesion to enterocytes was studied after deglycosylation of the bacterial cells and incubation with the selected intestinal microbiota strains that metabolize polysaccharides - Faecalibacterium prausnitzii DSM 17677 and Blautia luti DSM 14534. Both deglycosylation and incubation with polysaccharide metabolizing strains influenced the ability of probiotic strains to adhere to enterocytes. Enzymatic deglycosylation decreased adhesion efficiency of L. rhamnosus KL 53A; however, co-incubation of both lactobacillus strains with F. prausnitzii DSM 17677 resulted in an increase of their adhesion efficiency. Exopolysaccharides are important adhesins of Lactobacillus spp. that influence their ability to colonize gut epithelium. Other members of gut microbiota can modify the adhesion property in situ ; therefore the composition and metabolic state of commensal bacteria may influence their probiotic action.

Lactobacillus spp. belonging to the Casei group display a variety of adhesins.

BACKGROUND: n. Adhesion of bacteria from the genus Lactobacillus to the gastrointestinal epithelium is, to a considerable degree, dependent on the interactions between adhesins found on the surface of bacterial cells and elements found within the epithelium. A significant role in these interactions is played by bacterial pro teins exposed to the cell wall surface, which are capable of binding to molecules of substances comprising the extracellular matrix of the intestinal epithelium. METHODS: In order to analyze the extracellular proteome of intestinal bacteria in terms of the presence of cell adhesion molecules, a total of twenty strains from the Lactobacillus spp. group Casei were tested. The analyses were conducted using SDS PAGE, 2-D electrophoresis, Western blot and mass spectrometry. An experiment was also conducted to assess the adhesion capacity of the tested strains to cervical epithelial cells (HeLa). RESULTS: The tested strains varied in their adhesion efficiency to HeLa cells, ranging from 0.5% to 29%. Us- ing electrophoretic methods a total of 54 extracellular protein fractions were distinguished in these strains, additionally identifying potential adhesion molecules (e.g. a surface antigen of the NLP/P60 family and a small heat shock protein/chaperonin). CONCLUSIONS: The identification of these proteins in the extracellular proteome of Latobacillus spp. isolates may suggest that they serve currently unknown functions on the cell surface, including those connected with the interactions between bacteria and the intestinal epithelium. Such analyses may provide insight into new factors promoting probiotic adhesion to various types of epithelial cells.